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Table of Content
05 September 2015, Volume 66 Issue 9
    CIESC Journal(HUAGONG XUEBAO)Vol.66 No.9 September 2015
    2015, 66(9):  0-0. 
    Abstract ( 181 )   PDF (1974KB) ( 822 )  
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    Clean production of pharmaceutical crystallization
    GONG Junbo, CHEN Mingyang, HUANG Cui, QIN Yujia, YIN Qiuxiang, WANG Jingkang
    2015, 66(9):  3271-3278.  doi:10.11949/j.issn.0438-1157.20150904
    Abstract ( 298 )   PDF (1876KB) ( 624 )  
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    Pharmaceutical industry has been listed as one of the serious pollution industries in China. As the important and necessary part of pharmaceutical industry, crystallization technology should be optimized and updated to meet the clean production requirement. The pollution and waste caused by crystallization include toxic solvent applied, VOC emission, waste of mother liquor, bad properties of crystal product, and out-dated batch operation, etc. In face of these problems, the design methods and technology of clean production of pharmaceutical crystallization are reviewed and summarized. (a) Green crystallization. The solvent should be clean and effective. Single type of solvent and little consumption should be considered. Reduce the waste (gas, liquid and solid) emission by increasing crystal yield. Crystalline mother liquor and by-products should be reused and recycled. (b) Crystal engineering. Simplify the processes of filtering, washing, drying and tableting by optimizing crystal shape and interfacial properties. Solvates should be avoided to reduce the VOC emission. (c) Continuous crystallization. Compared with batch operation, novel continuous crystallization technology takes more advantages. (d) Intelligent device. Crystallization device should be optimized based on fluid dynamics to the benefit of crystal nucleation and growth. Integration of devices could reduce materials and energy consumption.

    Regulation on rates of mass transfer, reaction and separation via smart membranes
    XIE Rui, JU Xiaojie, WANG Wei, LIU Zhuang, CHU Liangyin
    2015, 66(9):  3279-3286.  doi:10.11949/j.issn.0438-1157.20150850
    Abstract ( 190 )   PDF (6230KB) ( 377 )  
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    Smart membranes change their surface wettability and pore size, and thus selectivity and permeability in response to the environmental stimuli, which are active topics of interdisciplines based on chemical engineering and materials science etc. The recent studies on the regulation of trans-membrane mass transfer and catalytic reaction rates as well as affinity separation efficiency based on smart membranes have been reviewed. Such processes provide attractive features such as mild condition, easy operation and regulation, and high efficiency, which provide new ways to achieve simple and high-efficient operations of mass transfer, separation and reaction.

    Recent development of efficient utilization of naphtha
    LI Xueqin, CAO Li, YU Shengnan, CHEN Silu, ZHANG Bei, JIANG Zhongyi, WU Hong
    2015, 66(9):  3287-3295.  doi:10.11949/j.issn.0438-1157.20150809
    Abstract ( 328 )   PDF (1765KB) ( 809 )  
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    To achieve the optimum utilization of naphtha resource, high efficient separation methods need to be explored for naphtha. In this review, the adsorption mechanism and recent technology for n-alkanes separation are briefly discussed. New types of adsorbents, including metal organic frameworks (MOFs), zeolite imidazole frameworks (ZIFs), carbon molecular sieve (CMS) and hollow zeolite molecular sieve, are introduced. Besides, the separation performance and separation mechanism of new adsorbents for n-alkanes separation are discussed. The feasibilities of new adsorbents, membrane separation technology and adsorption-membrane separation coupling technology for the separation of n-/iso-alkanes are also discussed. Novel technologies for n-alkanes separation from naphtha are proposed, which may offer new approaches for the efficient utilization of naphtha resource.

    Development of ion exchange membrane for all-vanadium redox flow battery
    LI Yan, XU Tongwen
    2015, 66(9):  3296-3304.  doi:10.11949/j.issn.0438-1157.20150993
    Abstract ( 323 )   PDF (1233KB) ( 872 )  
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    The all-vanadium redox flow battery (VRB) has received wide attention due to its excellent features for large-scale energy storage and stable power generation. As a key component in VRB, the ion exchange membranes (IEMs) not only separate the electrolyte, but also conduct ions to form charge-discharge circuit. In this work, an overview is presented for the various IEMs research of the vanadium redox flow battery. Relevant published work is summarized and critically discussed. The limitations and technical challenges in the ion exchange membranes are also discussed and further research opportunities are prospected.

    Recent advancements of Pt-free catalysts for polymer electrolyte membrane fuel cells
    NIE Yao, DING Wei, WEI Zidong
    2015, 66(9):  3305-3318.  doi:10.11949/j.issn.0438-1157.20150785
    Abstract ( 550 )   PDF (20338KB) ( 548 )  
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    The approaching commercialization of polymer electrolyte membrane fuel cells (PEMFCs) is still hindered by the high cost and limited operational stability of the Pt-based cathode catalysts traditionally utilized. Specifically, the cathode catalyst layer comprises over half of the overall cost of a PEMFC stack and the increasing demands for fuel cell power systems will undoubtedly drive up the already high price of Pt. Developing new catalyst with reduced Pt dependency, improved oxygen reduction reaction (ORR) activity and high stability is an urgent necessity. This paper reviews the recent advancements in the area of Pt-free electrocatalysts for ORR with emphasis on introducing the exciting new research in catalyst synthesis methodologies and the understanding of the mechanism of nitrogen-doped carbon nanomaterials. The integration of these catalysts into fuel cell operations and the resulting performance/durability, are also discussed. Meanwhile, the insights into the remaining challenges and research directions are proposed in order to shed light on the future development of Pt-free catalysts for ORR.

    Review on catalytic wet peroxide oxidation process
    LUO Lei, DAI Chengyi, ZHANG Anfeng, SONG Chunshan, GUO Xinwen
    2015, 66(9):  3319-3323.  doi:10.11949/j.issn.0438-1157.20150927
    Abstract ( 417 )   PDF (449KB) ( 689 )  
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    Catalytic wet peroxide oxidation (CWPO), as a highly effective treatment of toxic and harmful wastewater technology, is of great prospects and great promotional value in the field of printing and dyeing, pesticides, pharmaceuticals, etc. The basic concepts of this technology, reaction mechanism and catalyst performance, and the way to solve the catalyst activity and stability problems were reviewed.

    3D printing technology based on two-photon polymerization
    SONG Xiaoyan, XING Jinfeng
    2015, 66(9):  3324-3332.  doi:10.11949/j.issn.0438-1157.20150754
    Abstract ( 987 )   PDF (5792KB) ( 2493 )  
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    3D printing is a rapid prototyping technology based on an additive process. Stereolithography (SLA) as a mature 3D printing technology has been widely applied in industrial manufacture. SLA is the process of single-photon polymerization (SPP), and its resolution is controlled by the optical diffraction limit, which cannot meet the requirement for three dimensional micro/nanostructures with high resolution. Unlike SLA, 3D printing technology based on two-photon polymerization (TPP) induced by a near-infrared femtosecond laser can fabricate arbitrary and ultraprecise 3D microstructures with high resolution not only on the microscopic scale but also on the nanoscale. In this review, the principles of two-photon absorption and TPP were concisely explained. The development of TPP mainly focusing on TPP resolution and TPP initiators were introduced as well as the applications of 3D printing technology based on TPP. Finally, the perspective of 3D printing technology based on TPP was proposed.

    Research developments of low-temperature methanol synthesis
    SHI Lei, ZHANG Wanying, WANG Yuxin, Tsubaki Noritatsu
    2015, 66(9):  3333-3340.  doi:10.11949/j.issn.0438-1157.20150834
    Abstract ( 403 )   PDF (763KB) ( 631 )  
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    Conventional production of methanol is very inefficient since only 10%-15% one-pass conversion is achieved typically at 5.0-10.0 MPa and 523-573 K due to the severe thermodynamic limitations of its exothermal reaction (CO + 2H2 = CH3OH). A novel route of low-temperature methanol synthesis developed by Tsubaki et al from CO2-containing syngas only by adding alcohols including methanol itself is reviewed. These alcohols act as the homogeneous co-catalysts and solvent, realizing 70%-100% one-pass conversion at only 5.0 MPa and 443 K. The key step is the reaction of the adsorbed formate species with alcohols to yield ester species at low temperatures, followed by the hydrogenation of ester by hydrogen atoms on metallic Cu. This changes the normal reaction path of conventional, high-temperature methanol synthesis from formate via methoxy to methanol. A series of new methods, such as sol-gel auto-combustion, solid-state combustion and formic acid assisted combustion methods, to prepare highly active metallic Cu/ZnO catalysts without further reduction are also reviewed. During the decomposition of metal-contained precursors in an argon atmosphere, H2 and CO are liberated and act in situ as the reducing agents to obtain pure metals and metallic catalysts. The X-ray diffraction, X-ray photoelectron spectroscopy, energy dispersive spectroscopy, and temperature-programmed reduction analysis reveal that the as-prepared catalyst without further reduction is converted into metallic Cu0 and ZnO species.

    Research progress on deep treatment and reclamation of coal gasification wastewater
    ZHANG Runnan, FAN Xiaochen, HE Mingrui, SU Yanlei, JIANG Zhongyi
    2015, 66(9):  3341-3349.  doi:10.11949/j.issn.0438-1157.20150770
    Abstract ( 317 )   PDF (557KB) ( 1148 )  
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    The treatment of coal gasification wastewater is difficult because of its complex composition and many contaminants with high concentrations, such as oils, phenols and NH3-N. In this paper, the compositions and characteristics of the wastewater from coal gasification were analyzed and the feasibility of recent technologies for the deep treatment and reclamation of it were reviewed. Aiming to overcome the shortcomings of different technologies and to obtain high water recovery, the feasibility of multi-membrane technologies (ultrafiltration, nanofiltration, reverse osmosis, electrodialysis) for treating it deeply was specially discussed. At last, an outlook on the development trends of the technologies for the deep treatment and reclamation of coal gasification wastewater was given.

    Engineered Saccharomyces cerevisiae for biosynthesis of plant triterpenoids
    ZHU Ming, WANG Caixia, LI Chun
    2015, 66(9):  3350-3356.  doi:10.11949/j.issn.0438-1157.20150914
    Abstract ( 350 )   PDF (743KB) ( 944 )  
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    Triterpenoids (such as glycyrrhetinic acid, saponin ) is the main existence form of many drugs that play a pharmacological activities within the cells. Except used as the main active ingredients of drugs, some of them also can be used as a sweetener. But the amount of triterpenoids in plant (the origin source) is very low, which restrict its development and utilization. With the discovery of key enzymes in terpenoids metabolism, the whole metabolic pathway of terpenoids is clear increasingly. In recent years, the rapid development of synthetic biology lays a solid foundation for triterpenoids production by microbial fermentation. This paper reviews the triterpenoids biosynthesis pathway in Saccharomyces cerevisiae and cytochrome P450 monooxygenase (CYP450) which plays an important role in the whole pathway.

    Recent advances in sulfur-resistant methanation
    WANG Weihan, LI Zhenhua, WANG Baowei, XU Yan, MA Xinbin
    2015, 66(9):  3357-3366.  doi:10.11949/j.issn.0438-1157.20150876
    Abstract ( 317 )   PDF (653KB) ( 540 )  
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    Sulfur-resistant methanation have been investigated for their insensitivity to sulfur poisoning and high activities in the methanation reaction with low H2/CO ratios. Molybdenum-based catalysts were studied widely in literature. The effects of Al2O3, ZrO2, CeO2 and CeO2-Al2O3 supports, and CoO and NiO promoters on the performance of methanation catalysts were mainly introduced. The sulfidation mechanism for MoO3 and CoO/NiO promoted MoO3 catalysts and CeO2 support was critically analyzed based on the reported works. It was pointed out that the sulfidation temperature was a key factor to catalyst morphology. In addition, the mechanism of sulfur-resistant methanation was discussed. An overview regarding the opportunities for future research in sulfur-resistant methanation of CO was provided.

    Thermodynamic analysis on synthesis of diphenyl toluene dicarbamate via urea route
    CUI Xuexia, WANG Guirong, ZHAO Qian, LI Xin, ZHAO Xinqiang, WANG Yanji
    2015, 66(9):  3367-3376.  doi:10.11949/j.issn.0438-1157.20150879
    Abstract ( 265 )   PDF (941KB) ( 413 )  
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    The synthesis of diphenyl toluene dicarbamate from urea, toluene diamine and phenol is a complex reaction system. On the basis of the analysis for similar reaction system, four possible reaction pathways for synthesizing diphenyl toluene dicarbamate via urea route were proposed. The fundamental thermodynamic data of components in this reaction system were calculated by several methods of group contribution. The reaction enthalpy, Gibbs free energy change and equilibrium constant of all the reactions of the four possible reaction pathways were obtained. According to the results of thermodynamic calculation and experimental data in literature, the feasibility and difficulty of each reaction pathway were discussed. The results show that a better reaction pathway is urea reaction with phenol to give phenyl carbamate and then phenyl carbamate interacting with toluene diamine to form diphenyl toluene dicarbamate. The results from thermodynamic calculation and analysis can provide a theoretical basis for the experimental study and process development of the reaction.

    Measurement and correlation of viscosities of mixed solvents 1,3,5-trimethylbenzene and diisobutylcarbinol
    ZHANG Rongrong, DOU Maobin, YUAN Enxian, LI Haijing, WANG Li
    2015, 66(9):  3377-3382.  doi:10.11949/j.issn.0438-1157.20150860
    Abstract ( 327 )   PDF (468KB) ( 459 )  
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    The viscosities of mixed solvents consisted of 1,3,5-trimethylbenzene (TMB) and diisobutylcarbinol (DIBC) were determined at temperature ranging from 293.15 to 323.15 K and atmospheric pressure for the whole range of compositions by using viscometer. The excess molar viscosities of the mixed solvents were calculated and correlated by Redlich-Kister equation. The viscosities of the mixtures were correlated and predicted by Andrade equation, UNIFA-VISCO model, and Grunberg-Nissan model. The viscosities of the mixtures decreased with the increase of temperature and molar fraction of TMB. The excess viscosities showed negative deviations from ideal behavior, gave U-shaped curves as the molar fraction of TMB (x1) increased, and reached the minimum values at ca x1=0.3. The Grunberg-Nissan model was quite reasonable with the maximum and average relative errors between predicted and experimental data of 12.96% and 5.74%.

    CFD simulation of circulation flow caused by jet in DTB crystallizer
    LI Jixiang, HAO Tingting, LAN Zhong, MA Xuehu
    2015, 66(9):  3383-3390.  doi:10.11949/j.issn.0438-1157.20151049
    Abstract ( 270 )   PDF (636KB) ( 423 )  
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    The circulation jet flow field in a DTB evaporating crystallizer was simulated and analyzed using RNG k-ε turbulent model. Based on the Eulerian multiphase flow model, the structure of the crystallizer and the flow field in the crystallizer were simulated and optimized. The simulation results showed that the jet could satisfy linear expansion in the draft tube and the axial velocity distribution basically met the Gaussian distribution. For the jet flow at entrance region of the draft tube, the reciprocal of axis velocity and flow distance showed a good linearity. However, axial velocity decayed faster with the development of the jet flow. The area ratio (β) of the annulus between draft tube and the baffle to the cross-section of the draft tube significantly influenced the circulation flow ratio (γ). With the increase of β, γ increased at first, and then decreased, accordingly an optimal γ exists. Although the particle concentration of the crystal slurry decreased along the radial direction in the draft tube, it still had a more even distribution within the optimized structure crystallizer.

    Numerical analysis of reaction process and flow field in fixed bed of methanation reactor
    CHENG Yuanhong, ZHANG Yaxin, WANG Jide, ZHAO Jing
    2015, 66(9):  3391-3397.  doi:10.11949/j.issn.0438-1157.20150826
    Abstract ( 236 )   PDF (6674KB) ( 562 )  
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    Fixed bed of methanation reactor was simulated by inserting methanation reaction into simulation process in the form of the source term by using the CFD software to write CEL language. Then, by comparing the simulation accuracy of porous model and packed pebble-bed model, and choosing the packed pebble-bed model to simulate, the velocity field, the concentration of the components and the temperature field distribution in bed layer were obtained. The results showed that using the porous model to simulate fixed bed reactor caused greater error with the reason that porous model ignore the internal pore structure. The effect of wall in fixed bed significantly influenced on the field distribution. For example, 20% of the mass flowed through the area near the wall that shared only 10% of the total area. The axial temperature rose from 250℃ to 685℃ significantly and the radial temperature distribution was not uniform with a fluctuating range of within 20℃ to 40℃.

    Numerical simulation of gas-liquid two-phase flow in hydrodynamically focused microchannels
    LÜ Jianhua, LI Pin, GAO Mengfan, YIN Minghai
    2015, 66(9):  3398-3404.  doi:10.11949/j.issn.0438-1157.20150893
    Abstract ( 260 )   PDF (7031KB) ( 710 )  
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    The gas-liquid two-phase flow in the hydrodynamically focused microchannels was investigated via computational fluid dynamics (CFD) method. Film was formed in the micro-channels and the film formation process included three stages. Surface pressure, shear stress force and surface tension force were changed during the film formation process. The effects of two-phase pressure change on the two-phase flux and film thickness were investigated. The results of numerical simulation showed that the pressure changing had little influence with constant two-phase pressure ratio at 1, while changing the ratio showed the significant influence.

    Surface wettability effect on carbon dioxide-water two-phase flow and mass transfer in rectangular microchannel
    SUN Junjie, HAO Tingting, MA Xuehu, LAN Zhong
    2015, 66(9):  3405-3412.  doi:10.11949/j.issn.0438-1157.20151050
    Abstract ( 274 )   PDF (1455KB) ( 435 )  
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    An experimental investigation was conducted with a high-speed camera to explore the hydrodynamics characteristics of slug flow in a microchannel with a cross-section of 1 mm×1 mm. Pure carbon dioxide and water were used as working fluids. The influence of superficial gas and liquid velocities and the wettability of microchannel on the two-phase flow pattern and mass transfer was investigated. In the hydrophilic microchannel, bubbly flow, bubbly-slug flow and slug flow were observed. In the hydrophobic microchannel, asymmetric slug flow, elongated asymmetric slug flow, stratified flow were found. It was shown that in slug flow of the hydrophilic microchannel, the length of bubble increased generally with the increase of superficial gas velocities and the decrease of superficial liquid velocities. The length of liquid slug decreased generally with the increase of superficial gas velocities, and increased firstly and then decreased generally with the increase of superficial liquid velocities. As the improvement of superficial gas and liquid velocities, the liquid volumetric mass transfer coefficient kLa increased. The liquid volumetric mass transfer coefficient kLa in the hydrophilic microchannel was higher than that in the hydrophobic microchannel.

    Effects of MnOx supports on light olefin synthesis using cobalt catalyst in Fischer-Tropsch reaction
    LIU Yi, LIU Yong, CHEN Jianfeng, ZHANG Yi
    2015, 66(9):  3413-3420.  doi:10.11949/j.issn.0438-1157.20150867
    Abstract ( 303 )   PDF (1422KB) ( 682 )  
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    A series of Co/MnOx catalysts were prepared by impregnation method to investigate the effects of MnOx supports on selectivity of light olefins (C2=-C4=). The various catalysts were characterized by XRD, SEM, TEM, TPR and DRIFTS. The TPR results showed that the Co/MnO and Co/Mn3O4 were more easy to be reduced. The DRIFTS results indicated that Co/MnO and Co/Mn3O4 had much more adsorbed CO, which improved high CO conversion. The more bridge-adsorbed CO on Co/Mn2O3 and Co/Mn3O4 catalysts would contribute to forming more CH2 species. The FTS results revealed that Co/MnO and Co/Mn3O4 had better activity, and Co/Mn2O3 and Co/Mn3O4 realized better selectivity of C2=-C4=. The Co/Mn3O4 reached the 50.91% selectivity of C2=-C4= and olefin to paraffin ratio (O/P) of 3.40 within C2-C4.

    CeO2 nanoclusters stabilized in aerogel matrix as catalysts for Cl2 production from HCl oxidation
    XU Xihua, FEI Zhaoyang, CHEN Xian, TANG Jihai, CUI Mifen, QIAO Xu
    2015, 66(9):  3421-3427.  doi:10.11949/j.issn.0438-1157.20150902
    Abstract ( 205 )   PDF (1553KB) ( 363 )  
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    CeO2 nanoclusters inserted into aerogel matrix (CeO2@MxOy, MxOy= SiO2, ZrO2, Al2O3) prepared by a single-step sol-gel method were used as catalysts for recycling Cl2 from HCl oxidation. Due to their remarkable quantum-size effects, the properties of CeO2 nanoclusters were significantly different from crystal phase CeO2. The CeO2 nanoclusters could be completely reduced at the temperature range for reduction of the surface oxygen species of crystal phase CeO2. The unique properties of CeO2 nanoclusters resulted in the high activity of CeO2@MxOy in the process of HCl oxidation reaction. 40CeO2@SiO2 exhibited the highest activity and the STY (space time yield of Cl2) reached to 2.10 g·(g cat)-1·h-1 at 430℃ with VO2/VHCl of 1 and contact time of 0.1598 h. Kinetic studies showed that both O2 and HCl competed for the active sites rendering desorption of surface Cl as the rate-determining step.

    Relationship between Brønsted and Lewis acid sites on solid acid surface and product distribution from transformation of fructose to methyl lactate
    CHANG Cuirong, WANG Hua, HAN Jinyu
    2015, 66(9):  3428-3436.  doi:10.11949/j.issn.0438-1157.20150837
    Abstract ( 399 )   PDF (647KB) ( 587 )  
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    Catalytic conversion of fructose directly into alkyl lactate is one of the effective ways for use of biomass to produce high value-added chemicals. Research shows that one of main factors influencing the alkyl lactate yield is Lewis and Brønsted acid sites on the surface of solid acid catalysts. A series of solid acid catalysts with different acid sites and concentration is prepared, including γ-Al2O3, HZSM-5 zeolite, SnOPO4, SnZrOPO4(1:1), and SO42-/ZrO2. All of catalysts was characterized by using NH3 temperature-programmed desorption(NH3-TPD) and infrared spectroscopy with pyridine adsorption(Py-FTIR) techniques to figure out their total acid concentration, Lewis and Brønsted acid concentrations. The catalytic conversion of fructose in methanol over the five solid acid catalysts was studied. The results showed that the conversions of fructose can be higher than 98%; product distribution obtained depends greatly on Lewis and Brønsted acid amounts; and yield of methyl lactate lessened with the decrease of Lewis acid concentration. For γ-Al2O3 catalyst that contains only Lewis acid sites, the yields of methyl lactate achieved is 24.4%, while for these solid acid catalyst that contain both Lewis and Brønsted acid sites, the product obtained is not only methyl lactate but also methyl levulinate, and yield of methyl levulinate improves with increase of Brønsted acid concentration. Finally, the product distribution from the reactions catalyzed by typical Lewis acid solid catalyst γ-Al2O3 and HZSM-5 catalyst with both Brønsted and Lewis acid sites at different reaction time was investigated. Combined with the qualitative analysis obtained by gas chromatography-mass spectrometry(GC-MS), the reaction pathway for fructose conversion catalyzed by Lewis and Brønsted acid sites was proposed.

    Photocatalytic oxidation desulfurization by iron phthalocyanine supported on Ti-MCM-41
    ZHANG Juan, HU Yanhui, REN Tengjie, LI Weikang, ZHAO Dishun
    2015, 66(9):  3437-3443.  doi:10.11949/j.issn.0438-1157.20150863
    Abstract ( 225 )   PDF (1442KB) ( 434 )  
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    Titanium-silicium molecular sieve Ti-MCM-41 was synthesized and the iron phthalocyanines(FePcs) with different substituent groups were loaded onto the modified Ti-MCM-41 by covalent bond to prepare FePcs(R)/Ti-MCM-41 catalyst. FePcs(R)/Ti-MCM-41 were characterized by FT-IR, XRD, SEM, BET and UV-Vis DRS. Dibenzothiophene(DBT) was photo-oxidized with FePcs(R)/Ti-MCM-41 as photocatalysts, air as oxidant and CPL-CTAB ionic liquid as extraction agent in the irradiation of visible light under room temperature and atmosphere. The optimal reaction conditions were explored by simple variable method. The results showed that FePc(NH2)/Ti-MCM-41 exhibited a better photocatalytic activity and the removal ratio of DBT was up to 95.6% under the optimal reaction conditions. The catalytic performance of FePc(NH2)/Ti-MCM-41 did not decrease obviously after reusing 5 runs of oxidation.

    Kinetics study of Fischer-Tropsch reaction to lower olefins over MnOx-promoted Fe/SiO2 catalysts
    DAI Weiwei, LIU Da, FU Donglong, ZHANG Zhengpai, ZHANG Jun, XU Jing, HAN Yifan
    2015, 66(9):  3444-3455.  doi:10.11949/j.issn.0438-1157.20150751
    Abstract ( 496 )   PDF (786KB) ( 587 )  
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    The promotional effects of MnOx on the synthesis of lower olefins via Fischer-Tropsch reaction over Fe/SiO2 catalysts were investigated. It was found that CO conversion and STY(space time yield) of C2-C4 olefins was greatly enhanced with the addition of MnOx. CO2-TPD and CO-TPD (temperature program desorption) have evidenced that MnOx could enhance the surface basicity of Fe-based catalyst. The intrinsic kinetics for Fischer-Tropschto reaction to lower olefins (FTO) was measured under the realistic reaction conditions over Fe/SiO2 catalysts with and without MnOx by fitting power-law model. The apparent activation energies and reaction orders were calculated based on the formation of products and CO conversion. With combination of kinetics and temperature-programmed techniques, it was found that the MnOx promoter can enhance the dissociation of CO and inhibite the readsorption of lower olefins, leading to the enhancement of STY and the selectivity to lower olefins. Finally, the FTO reaction mechanisms of Fe-based catalysts, especially, the promotional effects of MnOx on Fe/SiO2 for the production of lower olefins, were speculated.

    Adsorption performance and photocatalytic activity of H3PW12O40 doped titanium dioxide photocatalyst
    YAO Shuhua, CHEN Shuang, ZOU Peichen, SHI Lei, SHI Zhongliang
    2015, 66(9):  3456-3461.  doi:10.11949/j.issn.0438-1157.20150815
    Abstract ( 335 )   PDF (1632KB) ( 562 )  
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    A series of titanium dioxide (TiO2) photocatalysts doped with H3PW12O40 were synthesized by sol-gel method using tetrabutyltitanate [Ti(OC4H9)4] and H3PW12O40 as precursors. The as-prepared photocatalyst was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and UV-vis adsorption spectroscopy. The adsorption performances and photocatalytic activities of the prepared samples were estimated by measuring the adsorption and degradation rate of methyl blue (MB) in an aqueous solution. The results of MB adsorption showed that H3PW12O40-doped TiO2 exhibited higher adsorption performance than pure TiO2 and the adsorption isotherm of MB on photocatalyst could be described better by Langmuir equation than Freundlich equation. The effects of catalyst dosage and H3PW12O40-doped content on the photocatalytic degradation of MB were studied. It was shown that the H3PW12O40-doped TiO2 had a stronger absorption and could thus be used as an effective catalyst in photo-oxidation reactions. In addition, the possibility of cyclic usage of H3PW12O40-doped TiO2 was also confirmed. The photocatalytic activity of the photocatalyst remained was above 88% of that of the fresh sample after being used four times.

    CFD simulation of fixed-bed methanation reactor with double catalyst layers
    ZHAO Jing, ZHANG Yaxin, RAN Wenshen, CHENG Yuanhong
    2015, 66(9):  3462-3469.  doi:10.11949/j.issn.0438-1157.20150828
    Abstract ( 327 )   PDF (5263KB) ( 995 )  
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    The temperature distribution has its influence directly on methane production and equipment safety of the fixed-bed methanation reactor. To research the adiabatic methanation reactor which can produce 1.275 billion cubic meters SNG a year, the three-dimensional entity model was set up. A gas-solid two-phase reactor model for chemical reactions, heat exchange and mass transfer in porous media was established by the software ANSYS-CFX. The internal profile of temperature, pressure and velocity field and the methane yield profile in the fixed-bed internal methanation reactor with double catalyst layers were obtained. Based on the finite element numerical simulation method, the characteristic field distributions of different bed structures were explored. The influence of the bed structure on each characteristic field profile was analyzed, and then, the structure optimization of the bed layer was determined. The structure of the end support extend model was more favorable of the temperature profile along the radial of the reactor and the improvement of the methane mass fraction. The entrance temperature, space velocity and entrance pressure were researched. Through the analysis of the parameters that influenced the degree of the reaction, the fluctuation ranges of the permitted entrance were put forward for this process.

    Isopropylation of 4-isopropybiphenyl to 4,4'-diisopropylbiphenyl over alkalis and acid modified mordenite zeolites
    LIU Min, SHEN Zhongming, GUO Xinwen, SONG Chunshan
    2015, 66(9):  3470-3475.  doi:10.11949/j.issn.0438-1157.20150849
    Abstract ( 190 )   PDF (5536KB) ( 344 )  
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    Isopropylation of 4-isopropybiphenyl to 4,4'-diisopropylbiphenyl was carried out over hierarchical mesoporousmordenite zeolites through alkalis modification of H-mordenite zeolite in a fixed-bed reactor. In order to investigate the effects of the pore structure and the acid sites of the zeolite samples on the catalytic properties, the parent and modified zeolite samples were thoroughly characterized with X-ray diffraction (XRD), transmission electron microscopy (TEM), ammonia temperature programmed desorption (NH3-TPD), and N2 physical adsorption-desorption. The results showed that the alkalis treatment adapted the pore structure, and the acid strength and amount without obvious destruction to the MOR topological structure. This adaption was contributed to the improvements of 4-isopropybiphenyl conversion and reaction stability. Modifying the sample with alkalis first and then followed by an acid treatment was in favor of removing the extra-framework alumina from the alkalis treatment and adapting the acid sites on the extra surface of the sample, which can successfully improve the selectivity of 4,4'-diisopropylbiphenyl.

    Poisoning effect of H2S on catalytic performance of AuCl3/AC in acetylene hydrochlorination
    DAI Bin, ZHANG Chunli, KANG Lihua, ZHU Mingyuan
    2015, 66(9):  3476-3482.  doi:10.11949/j.issn.0438-1157.20150861
    Abstract ( 238 )   PDF (2444KB) ( 413 )  
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    A study about poisoning effect of hydrogen sulfide (H2S) on the catalytic performance of AuCl3/AC during acetylene hydrochlorination deactivation is described and discussed. 1% AuCl3/AC catalyst is prepared by an incipient wetness impregnation technique. The activity tests demonstrate that H2S poisoning results in the rapid and irreversible deactivation of AuCl3/AC catalyst in acetylene hydrochlorination. Temperature-programmed reduction (TPR) and X-ray photoelectron spectra (XPS) show that H2S addition can effectively accelerate active Au3+ reduction to metallic Au0. The formation of metal sulfide may also be another reason for catalyst deactivation in the presence of H2S, which is supported by transmission electron microscopy (TEM) and energy dispersion X-ray spectrometer (EDX) techniques. In other words, with the increase of H2S added to the feed gases, the content of Au3+ is greatly reduced to metallic Au0. Moreover, the active sites are covered with Au-S compound. Both of them could reduce the effective active component, leading to the deactivation of the AuCl3/AC catalyst.

    Deactivation of HZSM-5 catalyst in methanol to gasoline
    ZHANG Xiangjing, MA Renjuan, SUN Ruiyu, LIU Yumin
    2015, 66(9):  3483-3489.  doi:10.11949/j.issn.0438-1157.20150891
    Abstract ( 240 )   PDF (522KB) ( 339 )  
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    The catalytic performances and the main deactivation mode of HZSM-5 zeolite were investigated by methanol to gasoline (MTG) reaction in a stainless-steel fixed bed reactor. The catalyst was characterized by means of techniques such as TGA-DTA, XRD, FT-IR, N2 adsorption-desorption and GC-MS. The results showed that the methanol conversion was 40% and the gasoline yield could drop to 12.6% after 336 h for the reaction, resulting in the serious deactivation of HZSM-5 catalyst. However, the regenerated catalyst at 700℃ in the air had high activity and the MFI framework structure. It was found that the coke, which deposited mainly on micropores of HZSM-5, was the main reason for catalyst deactivation. The main components of coke deposits were polymer with double bond or/and polycyclic aromatic hydrocarbon.

    Catalytic and selective transformation of glucose to methyl levulinate with mixed acids as catalysts
    ZHANG Yangyang, LUO Xuan, ZHUANG Xuli, TONG Xinli
    2015, 66(9):  3490-3495.  doi:10.11949/j.issn.0438-1157.20151018
    Abstract ( 305 )   PDF (1052KB) ( 470 )  
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    The efficient synthesis of methyl levulinate (MLE) from biomass feedstock using catalytic process is high economic, environment-friendly and sustainable in chemical industry. Herein, the catalytic performance of Lewis acid, Brøsted acid and mixed acid on the conversion of glucose to MLE is investigated in detail, and a satisfactory product yield is obtained. First, the different molecular sieves are combined with p-toluenesulfonic acid (PTSA) and employed as the catalysts for the direct transformation of glucose to MLE, in which the combination of Sn-β molecular sieve (being synthesized through a simple grinding method) and PTSA is the most efficient. The highest yield of MLE is about 68.3%. Furthermore, the catalyst is characterized by XRD, FT-IR and TG-DTG techniques. It is found that Sn-β can mediate the isomerization of glucose to fructose and PTSA mainly promote the alcoholysis reaction based on the experimental results and corresponding phenomena in the reaction. At last, the effects of Sn-β/PTSA ratio, reaction time and reaction temperature are studied, and the optimized conditions are obtained.

    Regression models of mechanical strength and porosity of V2O5-WO3/TiO2 deNOx catalysts by response surface methodology
    LI Qian, GU Huachun, XIN Ying, LI Zhuangzhuang, ZHANG Zhaoliang
    2015, 66(9):  3496-3503.  doi:10.11949/j.issn.0438-1157.20150847
    Abstract ( 251 )   PDF (5455KB) ( 304 )  
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    Selective catalytic reduction by NH3 (NH3-SCR) has been considered as one of the most efficient and mature techniques to eliminate nitrogen oxides (NOx) from coal-fired power plants. Therein, catalysts serve as the core of the whole system and study on their molding technology of the catalysts has become a hot topic. More and more attentions have been paid on how to mold a kind of catalysts with excellent deNOx performance and facile practical application. In this work, molding technology of V2O5-WO3/TiO2 deNOx catalysts was studied. Response surface methodology was used to investigate the regression models of mechanical strength and porosity of this kind of catalysts. The effects of pressing pressure and additive amount of PMMA microspheres on mechanical strength and porosity were evaluated and the significant regression models were obtained. High mechanical strength and porosity can be achieved when proper pressing pressure and additive amount of PMMA microspheres were chosen. It was shown by pore size distribution results that nano-micro hierarchical pores were obviously observed on the walls of catalysts. From XRD results, it was indicated that only anatase phase was found, possibly with high-dispersed V2O5 and WO3 species with low contents which cannot be detected. 80-90 m2·g-1 of surface areas can be obtained for this kind of catalysts by BET results. Micro pores were clearly observed by SEM after the addition of PMMA microspheres, which can increase the available surface area of catalysts, and thus decreasing the amounts and costs of catalysts. The results of activity tests showed that the honeycomb catalysts possessed excellent catalytic activity with high NOx conversion and N2 selectivity, which can meet the demands of deNOx in recent industry.

    Influence of pretreatment and metal cation modification of H-MOR zeolite on performance of DME carbonylation
    ZHAO Na, NIU Junyang, LIU Yahua, TAN Yisheng, LI Xingang
    2015, 66(9):  3504-3510.  doi:10.11949/j.issn.0438-1157.20150882
    Abstract ( 227 )   PDF (717KB) ( 362 )  
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    The influence of the pretreatment conditions and reaction temperature of the H-MOR zeolite on the performance of DME carbonylation was investigated. It was found that after the sample was pretreated in N2 flow at 500℃ for 2 h, the DME conversion reached 20.5% at 180℃. The DME conversion of the H-MOR increased with increasing reaction temperature, but the serious coking at higher temperatures resulted in the deactivation of the catalyst. Additionally, Cu, Fe, Ni and Co cations were used to modify the H-MOR zeolite, and to explore the influence of metal cation modification of the H-MOR zeolite on the performance of DME carbonylation. The catalytic tests showed that the IE-Cu catalyst was more active with the DME conversion of 36.9%, while the IE-Ni catalyst was more stable with the DME conversion of around 24.5% at the whole reaction period. Moreover, the influence of reduction temperature of the IE-Cu zeolite on the performance of DME carbonylation was also studied. The catalytic activity of the pre-reduced IE-Cu at 450℃was higher than that pre-reduced at 300℃.

    Process intensification by coupling reaction and extraction for CO2 mineralization in Ca2+-rich solution
    YE Longpo, LI Shuang, YUE Hairong, LI Chun, LIANG Bin, ZHU Jiahua, XIE Heping
    2015, 66(9):  3511-3517.  doi:10.11949/j.issn.0438-1157.20150981
    Abstract ( 281 )   PDF (1437KB) ( 491 )  
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    An intensified process by coupling the carbonation reaction and solvent extraction was proposed for CO2 mineralization in CaCl2-rich solution to capture CO2 and generate CaCO3 and NH4Cl. Tributylamine was used as the extractant to remove HCl from aqueous phase and precipitate CaCO3. Experiments showed that the precipitation ratio of Ca2+ reached ca. 98% at 1400 s. The organic phase could be spontaneously separated from the aqueous phase immediately after extraction, and recycled by reacting with NH3·H2O with a tributylamine regeneration ratio of ca. 98%. In addition, the experiment using low CO2 concentration (i.e., 15% CO2 in N2) could also reach a high level of 98.31% at a reaction time of 2700 s, which exhibited the potential to integrate CO2 capture and CO2 storage in a one-step process. The particle size distribution of calcite and the observation of water-in-oil structures indicated that the formation of calcite was occurred in the water-in-oil structures. This process, with simple apparatus, no heat input, unrequired CO2 capture cost and production of valuable CaCO3 and NH4Cl, greatly reduced the costs of CO2 sequestration, and might be an alternative method to solve the primary problem of the conventional high-cost CCS technology.

    Adsorption and separation of CH4-N2 with different structural MOFs
    HU Jiangliang, SUN Tianjun, LIU Xiaowei, LI Defu, ZHAO Shengsheng, WANG Shudong
    2015, 66(9):  3518-3528.  doi:10.11949/j.issn.0438-1157.20151059
    Abstract ( 236 )   PDF (739KB) ( 825 )  
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    For CH4-N2 separation with high-efficiency, several typical MOFs based on different ligands with high surface areas were synthesized in large scale via the simple solvothermal method, and their CH4/N2 separation performance was investigated experimentally by pure gas adsorption and binary gas breakthrough experiments. The results show that the adsorptive separation selectivity of most MOFs is much higher than that of Si/Al zeolites owing to their lower polarity, and the selectivity of MOFs with multidentate ligands are similar with that of high-quality activated carbon because their wide pore sizes resulted from the long linkers are not good for the separation of CH4/N2. In addition, the open metal sites in MOFs increase channel polarity, which is not conducive to improving the separation selectivity of CH4/N2 mixtures. Fortunately, the ultra-microporous adsorbent (0.5 nm) based on monodentate ligand, namely [Ni3(HCOO)6] synthesized by the short linker of HCOO- and Ni2+, has a much higher selectivity up to 7.0, twice that of conventional adsorbents, such as Si/Al zeolites and actvited carbons. In a word, the knowledge obtained in this work provides a foundation for the design of new nanoporous materials towards the CH4/N2 separation with high-efficiency.

    Electrodialysis for production of xylitol from acid hydrolysis method
    WANG Yaoming, PAN Shengdong, XU Tongwen
    2015, 66(9):  3529-3534.  doi:10.11949/j.issn.0438-1157.20150970
    Abstract ( 249 )   PDF (811KB) ( 362 )  
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    Xylitol is an important sugar alcohol widely used as sweetener. A processing route to remove the residual acid from xylose hydrolyzed solution in industrial production of xylitol is the acid hydrolysis method. Conventional neutralization method with lime has many drawbacks such as high energy consumption, large consumption of chemicals and environmental pollution. To achieve a clean production of xylitol, a self-resemble electrodialysis stack was used for selective removal of residue acid. The influences of current density on the removal ratio of residue acid and recovery ratio of xylose were investigated. The residue acid removal rate was higher than 99% and xylose recovery rate reached 84.9% at a current density of 30 mA·cm-2. The total energy consumption for xylose hydrolyzed solution was 179 kW·h·t-1 and the deacidification process cost was estimated to be 139 ¥·t-1, indicating economic and ecological advantages of this technology. Thus the electrodialysis is a very promising technology for production of xylitol.

    Numerical studies about intermediate purification of using hydrogen peroxide to produce hydrazine hydrate
    WANG Weiwen, ZHU Guojian, LI Jianlong
    2015, 66(9):  3535-3541.  doi:10.11949/j.issn.0438-1157.20150899
    Abstract ( 240 )   PDF (606KB) ( 606 )  
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    In the process of using hydrogen peroxide to produce hydrazine hydrate, the impurity was separated by the dividing wall column after the study on separation. Aspen Plus was used to simulation the process of isolation and purification of the components. The effect of factors such as feed location, feed temperature, reflux ratio and tower pressure were studied. The best process operating parameters were obtained to provide theoretical basis for the technology. The molar ratio of impurities to butanone collected from the top of the column was 0.023<0.03, reaching the standard for recovery. After optimization, 14.1% and 10.8% of the energy consumption of condenser and reboiler was saved, respectively. The theoretical plate number of main tower and deputy tower was 42 and 14, respectively. The feed position was 13 boards and the reflux ratio was 7 under operation pressure of 0.101 MPa. The percentage of the methyl ethyl ketone azine from the bottom of the tower was 98.2%.

    Separation of components from cinnamon oil by molecular distillation, thin-film evaporation coupling distillation technology
    WU Haibo, ZHANG Yujiao, FANG Yanxiong, YANG Zujin, RUI Zebao, YE Chao, XUAN Yaoming, JI Hongbing
    2015, 66(9):  3542-3548.  doi:10.11949/j.issn.0438-1157.20150895
    Abstract ( 262 )   PDF (640KB) ( 396 )  
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    In this study, a triple-integration technology including molecular distillation, thin-film evaporation, and distillation was adopted to separate cinnamon oil. The effects of distillation temperature, pressure and reflux ratio on the yield and purity of five components were investigated. Statistical calculations showed that the technology is successful in the separation of cinnamon oil. In order to understand the effects of separation factors, cinnamaldehyde is selected as a model compound. Based on a central composite design, the statistic model shows that distillation temperature and pressure have significant effects on the separation of cinnamaldehyde. The optimal values for highest yield and purity are as follows: temperature 95℃ and pressure 50 Pa. The experimental results are in agreement with the predicted values, indicating a successful application of response surface methodology in the optimization of separation parameters for cinnamon oil.

    Separation of CH4/N2 and CO2/CH4 mixtures in one dimension channel MOFs
    ZHANG Zhuoming, YANG Jiangfeng, CHEN Yang, WANG Yong, LI Libo, LI Jinping
    2015, 66(9):  3549-3555.  doi:10.11949/j.issn.0438-1157.20150892
    Abstract ( 228 )   PDF (1791KB) ( 639 )  
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    As powerful and effective supplement to conventional natural gas in future, the unconventional gas including low concentration coalbed methane and biomass need to remove a large amount of N2 and CO2 to achieve enrichment and purification of CH4. To separate N2 and O2, Cu(INA)2 with pores of a one-dimensional rhombus was chosen as an adsorbent. The synthesized sample was characterized with XRD and TG. Combined with CO2, CH4 and N2 adsorption curves, the grand canonical ensemble Monte Carlo (GCMC) molecular modeling and the ideal adsorbed solution theory (IAST) were used to calculate the adsorption heat of gas and adsorption selectivities for binary mixtures (CH4/N2 and CO2/CH4), separately; For breakthrough separation experiments, powder samples of Cu(INA)2 were pelletized into particles of a certain size under pressure of 3 MPa. The result revealed that Cu(INA)2 has not only high selective adsorption of CH4 in mixture of CH4/N2 (SCH4/N2=10), but also better separation for CH4/N2 than CO2/CH4.

    An efficient CuCl@β adsorbent with high CO adsorption uptake and CO/N2 and CO/CO2 selectivities
    HUANG Yan, YUE Yingyi, HE Liang, TAO Ying, PENG Junjie, XIAO Jing, LI Zhong
    2015, 66(9):  3556-3562.  doi:10.11949/j.issn.0438-1157.20150836
    Abstract ( 250 )   PDF (476KB) ( 1506 )  
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    A novel CuCl@β zeolite with high CO capacity and high-selectivity for CO/N2 and CO/CO2 mixtures was developed. A series of CuCl@β zeolites were prepared by an auto single-layer dispersion method. The CuCl@βzeolites were characterized by N2 adsorption and XRD. The adsorption isotherms and dynamic breakthrough curves of CO on the adsorbents were measured separately by a static adsorption and fixed-bed experiments. The adsorption selectivities of CuCl@β zeolite for CO/N2 and CO/CO2 mixtures were estimated on the basis of ideal adsorbed solution theory (IAST). The results showed that (a) the loading of CuCl onto β zeolite significantly enhanced CO adsorption capacity of the resulting CuCl@β adsorbent and the CuCl loading was optimized to be 0.4. (b) it not only significantly enhanced CO uptake, but also weakened N2 and CO2 adsorption on the CuCl@β adsorbents. As a result, it significantly enhanced CO/N2 and CO/CO2 selectivities of the adsorbent further, which can be attributed to the mild Cu+-CO interaction by π-complexation bond. (c) the 0.4CuCl@β adsorbent achieved a superior adsorption selectivity up to 1600-5200 and 120-370 at low pressure range of 0-10 kPa for CO/N2 and CO/CO2 mixtures, much higher than parent β zeolite. The high CO adsorption capacity and selectivity of CuCl@β adsorbents made it a promising adsorbent for CO/N2 and CO/CO2 separation.

    Progressively frozen condensation crystallization of oxiracetam
    DU Shichao, LI Kangli, ZHANG Yu, GAO Zhifeng, WANG Chenguang, GUO Baisong, LI Daixi, TANG Weiwei, GONG Junbo
    2015, 66(9):  3563-3569.  doi:10.11949/j.issn.0438-1157.20150903
    Abstract ( 211 )   PDF (11973KB) ( 250 )  
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    It is found that direct freeze-drying method is not applicable to oxiracetam because of long time and poor product quality. In this paper, MS software is used to calculate the molecular interactions between additive (sorbitol) and different crystal surfaces of oxiracetam. These values are very small and could be neglected. Experiments also show that the crystal form and morphology are independent of sorbitol in freeze-drying process. Analyzed by differential scanning calorimetry and hot-stage microscopy, glassy sate of oxiracetam prescription is identified during original prefreezing process, against sublimation of water molecules. Therefore, we propose a gradual congelation crystallization technology to change the crystal state of sorbitol, congeal every component and separate them in microcrystalline. According to results of larger scale experiments, this new technique greatly shortens the time required and improves the product quality.

    Simulation and optimization of extractive distillation for separation of azeotropic benzene/cyclohexane system
    ZHAI Jian, LIU Yuliang, LI Lumin, WANG Qiuyuan, SUN Lanyi
    2015, 66(9):  3570-3579.  doi:10.11949/j.issn.0438-1157.20150781
    Abstract ( 538 )   PDF (3950KB) ( 1487 )  
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    The separation of benzene and cyclohexane with furfural as entrainer was studied using conventional extractive distillation, extractive dividing wall column distillation and heat integrated pressure-swing extractive distillation. The three whole processes were simulated by commercial process simulator Aspen Plus V8.4. The sensitive analyses of all steady-state designs were carried out and the optimal flow sheets with minimum energy requirements have been established using the multi-objective genetic algorithm with constrains. Compared with the conventional configuration, the extractive dividing wall column distillation and heat integrated pressure-swing extractive distillation process with minimum heat duty of the reboiler presented the energy savings of 21.5% and 15.7%, respectively. The economic analysis was carried out to evaluate the economic feasibility of the three processes. The results clearly demonstrated that when compared with the conventional extractive distillation process, the total annual cost was reduced by 6.0% in the extractive dividing wall column and increased by 50.8% in the heat integrated pressure-swing extractive distillation, which provided a theory basis and design reference for the industrial design for extractive distillation process to separate azeotropic benzene and cyclohexane system.

    Cooling crystallization of paracetamol in ethanol solution based on real-time ATR-UV measurement
    GUAN Guoqiang, TANG Kai, LI Hong, LU Shuaitao, JIANG Yanbin
    2015, 66(9):  3580-3587.  doi:10.11949/j.issn.0438-1157.20150763
    Abstract ( 275 )   PDF (2419KB) ( 365 )  
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    Real-time concentration determination is critical in process analytical technology for advance quality control of crystallization. A novel approach is presented to correlate in-situ concentration of paracetamol in ethanol solution with the attenuated total reflection/ultraviolet (ATR-UV) spectrum by using the partial least squares method. The correlated concentrations are well consistent with the measurement of gravimetric method and the root-mean-square derivation is found to be 0.0075. Supersaturation correlation based on the developed ATR-UV in-situ concentration measurement, coupled with focused beam reflection measurement for monitoring the nucleation and growth during crystallization procedure, is utilized to investigate the effect of three cooling policies on cooling crystallization, i.e., natural cooling policy (NCP), linear cooling policy (LCP) and control cooling policy (CCP). The results show that the CCP has advantages over NCP and LCP in producing more crystals with the large and well-distributed crystal sizes.

    Reversible gas membrane process-multiple effect membrane distillation-distillation process for removing ammonia from aqueous solution and producingaqueous ammonia
    WANG Yun, QIN Yingjie, HAO Xingge, LI Haiqing, CUI Dongsheng, LIU Liqiang, LIU Jing
    2015, 66(9):  3588-3596.  doi:10.11949/j.issn.0438-1157.20150901
    Abstract ( 302 )   PDF (633KB) ( 592 )  
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    The integrated process of reversible gas membrane process (RGM)-multiple effect membrane distillation (MEMD)-distillation can be used to remove ammonia from aqueous solution and to get highly purified and concentrated aqueous ammonia as by-product. The performance of ammonium dihydrogen phosphate as reversible absorbent in the RGM process and the performance of regeneration process of the used absorption solution by using MEMD- distillation were studied. The experimental results showed that the mass transfer coefficient and ammonia removal rate of RGM process could be up to 13.9 μm·s-1 and 97.5% respectively when polytetrafluoroethylene (PTFE) hollow fiber membrane contactor was used, ammonia content in the aqueous feed could be reduced to < 5 mg·L-1. By using MEMD-distillation coupled system, the used absorption solution could be regenerated and a concentrated aqueous ammonia solution of 5%-18% was produced as by-product. The integrated process has extremely low energy consumption. While the power consumption is very low, the thermal consumption is steam of 28-40 kg·m-3 aqueous solution, which is less than 1/5 of the traditional distillation (steam stripping) process. Furthermore, this integrated process effectively avoids the pollution from the volatile components from the aqueous feed. The process has harsh requirement in the stability of microporous hydrophobic membrane modules used in the RGM and MEMD process, and the long-term operation stability test demonstrates that microporous hydrophobic PTFE membrane could satisfy this requirement.

    Adsorption of quinoline on zeolite Al-MCM-41
    WANG Yunfang, BU Changjuan, CHI Zhiming, LI Qian
    2015, 66(9):  3597-3604.  doi:10.11949/j.issn.0438-1157.20150817
    Abstract ( 213 )   PDF (680KB) ( 449 )  
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    Under basic conditions, Al-containing mesoporous zeolite Al-MCM-41 was successfully synthesized by hydrothermal synthesis method using sodium metasilicate as silica source, sodium aluminate as alumina source and CTAB as templating agents. XRD and BET were used to investigate the characterization of Al-MCM-41. The adsorptive capacity of this mesoporous zeolite for quinolone was analyzed through adsorption experiment for the nitrogen compounds in diesel in a continuous fixed bed reactor. The thermodynamic performance of the adsorption process was investigated in the range from 353.15 K to 393.15 K. Langmuir and Freundlich isothermal adsorption models were employed to fit the experimental data. The results of characterization showed that Al-MCM-41 with Si/Al 60 had larger pore volume, specific surface area and narrow pore distribution. The mesoporous molecular sieve had good crystallization degree and ordered pore structure. The adsorption of quinoline on zeolite Al-MCM-41 with Si/Al 60 was in accordance with the Freundlich isothermal adsorption model. The thermodynamic parameters, such as ΔH, ΔG, ΔS and apparent activation energy, were calculated to be -0.7682 kJ·mol-1, -28.1215 kJ·mol-1, 73.2434 J·mol-1·K-1 and 2.8575 kJ·mol-1, respectively. Pesto-second order rate equation was better to describe adsorption of quinolone.

    Properties of hybrid SPEK-C/GO composite proton exchange membranes
    WANG Lisha, LAI Aonan, ZHUO Yizhi, ZHANG Qiugen, ZHU Aimei, LIU Qinglin
    2015, 66(9):  3605-3610.  doi:10.11949/j.issn.0438-1157.20150874
    Abstract ( 311 )   PDF (871KB) ( 426 )  
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    A series of sulfonated phenolphthalein side poly (aryl ether ketone) (SPEK-C)/graphene oxide (GO) hybrid composite proton exchange membranes was fabricated. The effect of GO as a filler blending with SPEK-C was investigated systematically. The results indicated that GO content in the membrane had a great influence on ionic exchange capacity, stability, proton conductivity and methanol permeability. The proton conductivity was enhanced with increasing GO content. Moreover, the proton conductivity of the composite membranes with 2% and 5% GO was all above 10-1 S·cm-1 at 30℃. The composite membrane containing 5% GO exhibited methanol permeability of 6.7×10-8 cm2·s-1 at 30℃, which was one order of magnitude lower than that of SPEK-C membrane. The ionic exchange capacity, stability and water uptake were enhanced, and the relative selectivity reached up to 18.2 times higher than that of the SPEK-C membrane.

    Estimation of appropriate pore size distribution for diesel desulfurization adsorbent based on hindered diffusion model
    XU Chengzhi, ZHENG Meiqin, XIONG Ying, HUANG Qingming, CHEN Xiaohui
    2015, 66(9):  3611-3617.  doi:10.11949/j.issn.0438-1157.20150877
    Abstract ( 192 )   PDF (1136KB) ( 388 )  
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    Major sulfur components in 0# diesel conformed to PRC State Standard Ⅱ, Standard Ⅲ and Standard Ⅳ were identified by a gas chromatograph (GC) equipped with a pulsed flame photometric detector (PFPD). The PFPD chromatograms illustrated that benzothiophene (BT), dibenzothiophene (DBT) and their derivatives constitute significant portion of the sulfur species in ORD, majority of which were derivatives of DBT. BT, DBT and 4,6-dimethyldibenzothiophene (4,6-DMDBT) were treated as the characteristic sulfur species in diesel. The hindered diffusion coefficients of characteristic sulfur species in different sizes pore were estimated by a simplified hindered diffusion model. By combining with the stacking pore model of alumina, the appropriate pore size distribution for fuels desulfurization adsorbent was estimated. The results showed that when the average pore diameter of the alumina is 4-10 nm, the hindered diffusion coefficients of characteristic sulfur species were about 0.24 to 0.65 and the specific surface area of the alumina was about 100-250 m2·g-1, which can meet the lower diffusion resistance and a sufficiently large specific surface area, simultaneously. There was a significant positive correlation between the desulfurization rate of 0# diesel conformed to PRC state standard II and the percentage of pore area in the range of 4-10 nm. It was preliminary conjectured that the appropriate pore size distribution of alumina-based adsorbent for fuels desulfurization was in the range of 4-10 nm.

    Operation and control of extractive distillation for separation of azeotropic benzene/cyclohexane system
    LIU Yuliang, ZHAI Jian, LI Lumin, WANG Qiuyuan, SUN Lanyi
    2015, 66(9):  3618-3632.  doi:10.11949/j.issn.0438-1157.20150782
    Abstract ( 361 )   PDF (1199KB) ( 945 )  
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    In this study, the performance of conventional extractive distillation, heat integrated pressure-swing extractive distillation, and extractive dividing wall column distillation is investigated for the separation of benzene and cyclohexane with furfural as entrainer. Based on steady state design, the dynamic control of these three systems is studied with assistance of Aspen Dynamics, and several control structures for each system are presented to handle the feed flow rate and feed composition disturbances. The dynamic simulation results reveal that, for the conventional extractive distillation process, control structure with reboiler duty being proportional to the feed flow rate shows its superiority when it comes to the feed disturbances. In the heat integrated pressure-swing extractive distillation process, the system is sensitive to the pressure. For this reason, pressure-compensated temperature control scheme is proposed based on another control structure, and its dynamic responses reveal that the feed disturbances can be objected effectively. For the extractive dividing wall column distillation process, control structure without vapor split ratio as a manipulated variable, which is easier for to be realized in industrial production and can maintain the product purities at their specifications, is chosen rather than the one with vapor split ratio.

    Crystallization process and growth mechanism for spherical products of clopidogrel sulfate
    WANG Haiyang, DU Yanni, LI Zhenfang, SONG Xiaopeng, TAN Duanming, GONG Junbo
    2015, 66(9):  3633-3639.  doi:10.11949/j.issn.0438-1157.20151084
    Abstract ( 381 )   PDF (2666KB) ( 731 )  
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    The difference between solubility of clopidogrel sulfate form Ⅰ and form Ⅱ in 2-butanol was determined by dynamic method. Based on process analysis and optimization of clopidogrel sulfate crystallization in solutions, clopidogrel sulfate of form Ⅰ was acquired with spherical shape. Compared with the non-spherical products, the spherical one possesses advantages in bulk density, flow ability, size distribution and stability. The crystal habit and crystal form of products prepared at different temperatures and residual solvents were investigated, the kinetics and growth mechanism of the spherical crystallization process was studied.

    Separation, purification and composition analysis of bio-oil from hydrothermal liquefaction of microalgae
    FANG Lina, CHEN Yu, LIU Ya, WU Kejing, WU Yulong, YANG Mingde
    2015, 66(9):  3640-3648.  doi:10.11949/j.issn.0438-1157.20151022
    Abstract ( 242 )   PDF (618KB) ( 574 )  
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    In the present paper, the bio-oil produced from hydrothermal liquefaction of D. tertiolecta was divided into n-hexane, chloroform and diethyl ether fractions via solvent division at first, and then chloroform fraction was purified by column chromatography. The n-hexane and diethyl ether fractions were directly analyzed by GC-MS and FT-IR, while the separation products obtained from column chromatography of chloroform fraction were combined with secondary mass spectrometry and FT-IR to confirm the product information. The results showed that chloroform fraction can be divided into sixteen components including the petroleum ether fraction (A1) mainly in alkenes, petroleum ether:ethyl acetate fraction (A2) mainly in carboxylic acid, petroleum ether:acetone fraction (A3) mainly in amides, petroleum ether:methanol fraction (A4) mainly in higher alkanes, and methanol fraction (A5) mainly in amides. In addition, the product recovery was reached up to 91.38% after the purification via column chromatography. Meanwhile, some components, which cannot be directly detected by GC-MS, were identified after column chromatography. The results gave a comprehensive insight in the compositions of product obtained from microalgal liquefaction, which provided the basis on further understanding of HTL mechanism and bio-oil upgrading.

    Safety analysis of FCCU reaction-regeneration system underabnormal conditions
    JIN Manman, TIAN Wende, ZHANG Junmei
    2015, 66(9):  3649-3653.  doi:10.11949/j.issn.0438-1157.20150866
    Abstract ( 260 )   PDF (394KB) ( 327 )  
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    Fluid catalytic cracking unit (FCCU) is one of the key processes in modern petroleum refinery, where reaction-regeneration system is the core technology. Researches about reaction-regeneration system are very active in domestic and abroad, but mainly focusing on the influences of process parameters on reactive process. Reaction-regeneration system is a complex system due to its multivariable, time-varying and nonlinear characteristics, and thus the modeling of the system of complex kinetics reactions should be studied. A dynamic model is put forward to study the operating characteristics of system. Based on the equations of material balance, energy balance, general mechanism mathematical models are established. With field data and MATLAB software to solve the kinetic parameters, a user-friendly simulation system is developed and a steady-state production is achieved. With the established simulation system as the platform, four frequently encountered abnormal conditions are simulated and their influences on some important parameters are obtained. These parameters are plotted into curves and fitted into formulas and the theory of just-in-time is applied to the dynamic nonlinear analysis.
    Results show that the study of dynamic security analysis of abnormal conditions in the reaction-regeneration system is effective. The simulation of process is realistic in observing changes caused by abnormal operating conditions. When the changes of important parameters are known, the theory of JIT can infer certain abnormal conditions within a certain range, and draw the changes of the specific parameters during this abnormal condition. The processes running in different states are identified effectively. The accuracy and validity of the mathematical model are tested. This paper provides a new method for the identification of dynamic systems.

    Preparation of monodisper microsphere by controlled droplet solidification
    LI Chunlin, XIE Hua, LIU Na, LIN Bingcheng, LIU Zhongmin
    2015, 66(9):  3654-3660.  doi:10.11949/j.issn.0438-1157.20150919
    Abstract ( 233 )   PDF (11833KB) ( 247 )  
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    Uniform size micromeres functional material gets a lot of attention in the fields of polymer chemistry, medicine and chemical industry, catalysis and separation. It is incovenient to prepare monodisperse and uniformity micrometer material by current conventional technology. With microfluidic technology, the droplet was generated in the chip and following to solidify the droplet online to prepare various of monodisperse and size uniformity microsphere. Since the droplet was a Si sol of slow-solidified, the nonporous SiO2 microsphere with a BET surface area of 572 m2·g-1 and a variance coefficient of microsphere diameters of about 2% were produced by introducing precipitator from the interface of droplet. Because the droplets were a material of fast-precipited, such as Zn, Fe, or Cu ion, a hollow microsphere consisted of hydrate oxide or mixed oxide was produced. As the droplet contains both materials of fast-precipitated and flow-solidified, such as Si sol containing of Fe ion, SiO2 microsphere with a homogeneous dispersed Fe in it was obtained by adjusting the introducing velocity of precipitator into the droplet.

    Preparation of Au nanowires based on synergistic action of Pichia pastoris cells and surfactant
    JING Xiaolian, HUANG Dengpo, HUANG Jiale, SUN Daohua, LI Qingbiao
    2015, 66(9):  3661-3668.  doi:10.11949/j.issn.0438-1157.20150925
    Abstract ( 245 )   PDF (6411KB) ( 307 )  
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    Au nanowires (AuNWs) were obtained by the reduction of HAuCl4 with ascorbic acid (AA) under the synergistic action between microorganism (Pichia pastoris cells, PPCs) and hexadecyltrimethylammonium bromides (CTAB). SEM, TEM, HRTEM and SEAD were used to characterize the shape and structure feature of the Au nanoproducts. The results showed the AuNWs were hierarchically branched polycrystal and the interfaces of the branched positions were continuous in lattice. The interaction process between the microorganism and CTAB was researched and it was found that Au(0) could be formed on the PPCs surface, which acted as the seeds for the formation of AuNWs after AA addtion. Without the interaction process between the microorganism and CTAB, the Au nanoparticles instead of nanowires were acquired. Too long time adsorption between PPCs and HAuCl4 led to stable Au(0) on the microorganism surface, which was also unfavorable for the subsequent growth of AuNWs. The synergistic action between microorganism and CTAB resulted in the formation of AuNWs with hierarchically branched polycrystalline structure.

    Improvement of thermostability of recombinant β-glucuronidase by glycosylation
    WANG Xiaoyan, FAN Yanshuang, HAN Beijia, FENG Xudong, LI Chun
    2015, 66(9):  3669-3677.  doi:10.11949/j.issn.0438-1157.20150885
    Abstract ( 282 )   PDF (5008KB) ( 486 )  
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    To improve the thermostability of recombinant β-glucuronidase expressed in Pichia pastoris (PGUS-P) by N-glycosylation, new N-glycosylation sites were semi-rationally designed according to the simulated structure of PGUS-P. Three new N-glycosylation sites with EAS (enhanced aromatic sequence) were introduced by site-specific mutagenesis. After expression in Pichia pastoris, three mutant enzymes with new N-glycosylation were obtained, named as PGUS-P-26, PGUS-P-35 and PGUS-P-259. The kinetic analysis indicated that Vmax of PGUS-P-35 was improved from 111.25 μmol·(L·min)-1 to 120.48 μmol·(L·min)-1 and all of the three mutant enzymes showed a greater affinity and catalytic efficiency towards substrate glycyrrhizin compared to PGUS-P. The thermostability of PGUS-P-35 and PGUS-P-259 at 65℃ increased by 13% and 11% compared with that of PGUS-P, respectively. This study demonstrated that the introduction of N-glycosylation at the suitable region of enzyme could increase its thermostability.

    Plant-mediated synthesis of silver nanoparticles and applicationin antibacterial fabric
    SUN Daohua, LIU Zhaoyan, XIAO Zhengli, ZHENG Yanmei, HUANG Jiale, LI Qingbiao
    2015, 66(9):  3678-3684.  doi:10.11949/j.issn.0438-1157.20150859
    Abstract ( 225 )   PDF (5472KB) ( 513 )  
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    Nano silver, based on the nanoscience and nanotechnology, exhibits excellent antibacterial ability due to the quantum effect and size effect. In this work, the plant-mediated synthesis of silver nanoparticles (AgNPs) was reported from four plants, including Scutellaria baicalensis, Syzygium aromaticum, Syzygium samarangense and Cinnamomum camphora. The as-synthesized AgNPs were characterized by UV-Vis, TEM and XRD techniques. The results indicated that the AgNPs tended to be smaller with the increase of biomass concentration or NaOH adding amounts. SEM images verified that the AgNPs can be loaded onto cotton fabric through impregnation, and the optimal conditions were time of 30 h, temperature of 55℃ and liquor ratio of 1:25. Furthermore, the effects of AgNPs size and plant species on the antibacterial ability of the resulting Ag-coated fabrics were investigated, respectively. AgNPs loaded on the fabrics with smaller size displaied superior antibacterial activity against Escherichia coli. Moreover, Ag-coated fabrics prepared from Scutellaria baicalensis and Syzygium aromaticum extracts, which possessed own antibacterial ability, showed the cooperative antibacterial effect between biomass and nano-silver. The as-prepared fabric by the extract of Scutellaria baicalensis exhibited the best antibacterial ability with high inhibition ratio against various bacteria such as Staphylococcus aureus and Escherichia coli.

    Mechanical characteristics analysis of deflector-porous fence
    CHEN Guanghui, BAI Xuehua, LI Jianlong
    2015, 66(9):  3685-3691.  doi:10.11949/j.issn.0438-1157.20150897
    Abstract ( 239 )   PDF (5528KB) ( 352 )  
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    The force and structural stability of new type deflector-porous fence and traditional flat-porous fence with square or circular hole and porosity of 30% for all the three kinds of fences were studied using CFD software Fluent 6.2. The results showed that there was no obvious increase about wind load between deflector-porous fence and tradition ones, and the wind-load increased with increasing wind speed, showing a quadratic growth. The wind-load growth about 20 times when wind speed increased from 3 m·s-1 to 15 m·s-1. There was no obvious difference of the ratio of force arm and fixed fence high among different fences and little change with increasing wind velocity. The main reason of the formation of porous fence resistance was the different pressure before and after fence and the development of trailing vortex turbulence.

    An assessment of life-cycles on solid amine for adsorbing low-concentration CO2 in confined spaces
    YU Qingni, SI Wenting, YANG Bin, ZHU Jingke, LEI Lecheng
    2015, 66(9):  3692-3697.  doi:10.11949/j.issn.0438-1157.20150870
    Abstract ( 277 )   PDF (1601KB) ( 740 )  
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    To meet the requirement of a life support system, it is essential to develop an adsorbent with high stability and efficiency for removing low-concentration CO2 in confined spaces, such as spacecraft, space laboratory and submarine. Solid amine adsorbent was prepared by impregnating a polymer substrate with tetraethylenepentamine (TEPA), and its performance and stability in adsorption/desorption cycles under actual working condition for the removal of CO2 in confined spaces were examined. Test of long period life (about one year) was carried out to verify its stability. The results showed that the adsorption performance remained stable after 2128 and 2267 cycles. Under the condition of the life tests, CO2 adsorption capacities were maintained at ~28 mg·g-1. Moreover, no significant loss of organic amine was found according to thermal analysis and CO2 titration, and the high mechanical strength was still kept. It demonstrated that high adsorption efficiency of CO2 on the solid amine adsorbent at room temperature (20℃) was achieved and the CO2 desorption process can be conducted at the mild conditions (30℃), which is not only beneficial for reduction of energy consumption but also extend the service life. Therefore, the solid amine adsorbent, TEPA supported onto polymer substrate, could effectively be alternative for removal of CO2 in confined spaces.

    Reductive removing selenium from electrolytic manganese anolytewith iron powder
    WANG Yuhong, LÜ Yan, NONG Jingyi, LAN Ziliu, JIANG Jialuan, SU Haifeng
    2015, 66(9):  3698-3704.  doi:10.11949/j.issn.0438-1157.20150873
    Abstract ( 240 )   PDF (2798KB) ( 401 )  
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    The process of using iron powder to remove selenium from electrolytic manganese anolyte was investigated. The effects of variables such as stirring speed, iron powder dosage, sulfuric acid concentration and temperature were assessed. Experimental results indicated that the maximum remove rate of selenium to be 100% at a stirring speed of 600 r·min-1, iron powder dosage of 400 mg·L-1, sulfuric acid concentration of 50 g·L-1 and temperature of 30℃. XRD and SEM analyses showed that temperature had a significant influnence on the structure of selenium residue. There had four phase Se, Fe, FeSe2 and Fe2(SeO4)3 existed in the slag after reaction at 30℃, and the crystallization morphology was spindle. The phase existed in the slag after reaction at 90℃ were Se and FeSe2, and the morphology of crystals was sperical. The removing process was controlled by interface control. The apparent activation energy of removing selenium was determined to be 15.94 kJ·mol-1.

    Immobilization of laccase on magnetic SiO2 through dopamine self-polymerization for 4-CP removal
    ZHANG Di, DENG Manfeng, ZHAO He, CAO Hongbin, ZHANG Songping
    2015, 66(9):  3705-3711.  doi:10.11949/j.issn.0438-1157.20150871
    Abstract ( 326 )   PDF (758KB) ( 884 )  
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    In recent years, laccase has been reported to be successfully immobilized on many different supports. Among them, potential applications of magnetic silica microspheres have been widely investigated for enzyme immobilization and the enzymatic stabilities can improve obviously. However, to the best of our knowledge, there is no report for the laccase immobilization on silica coated nanoparticles via one-step dopamine (DA) self-polymerization method, and nor any reports concerned with the degradation performance of paraphlorophenol (4-CP) by this immobilized laccase. In this work, the immobilized laccase on silica-coated magnetic nanoparticles were prepared through dopamine (DA) in situ entrapment, and then the immobilized laccase was applied for 4-chlorophenol (4-CP) removal. Briefly, the silica-coated magnetic nanoparticles were prepared through a sol-gel method, then the mixture of Fe3O4@SiO2 nanoparticles and DA was added to PBS (pH 6.0) containing laccase, the reaction was performed for 18 h at 25℃ with vigorous stirring, and was separated by an external magnetic field. After being washed 4 times, the product (Fe3O4@SiO2-PDA-Lac) was obtained. The scanning electron microscope images and size distribution analysis indicated that Fe3O4@SiO2 had a spherical and uniform size distribution with the average diameter of about 134 nm. The high saturation magnetization of Fe3O4@SiO2 made it easily to be separated from the reaction system. The results of X-ray diffraction (XRD) revealed that the prepared samples were Fe3O4 nanoparticles and Fe3O4@SiO2 nanoparticles. The preparing conditions of the Fe3O4@SiO2-PDA-Lac were optimized by orthogonal experiment. In the best level, the total activity recovery of the Fe3O4@SiO2-PDA-Lac can reach to 43.28%. In the degradation process, the effects of laccase concentration, solution pH and ABTS mediator on the removal efficiency of 4-CP were investigated. The results showed that when solution pH was 6 and laccase concentration was 1.2 U·ml-1, 95% percentage of 4-CP was removed within 8 h enzymatic catalysis. When 50 μmol·L-1 of ABTS was added in the reaction system, the removal efficiency of 4-CP kept about 99% within 10 min enzymatic catalysis, which certified that the ABTS as a mediator could enhance the enzymatic reaction rate of the immobilized laccase. After degraded 10 times by the immobilized laccase, the removal efficiency of 4-CP still remained 67%, which exhibited an excellent reusability and operational stability.

    Preparation and adsorption kinetic analysis of kaolin-Li4SiO4
    XIE Hongyan, DING Tong, LI Yulong, GAO Nuonuo
    2015, 66(9):  3712-3718.  doi:10.11949/j.issn.0438-1157.20150896
    Abstract ( 193 )   PDF (6455KB) ( 631 )  
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    With kaolin-SiO2 as silicon source, lithium orthosilicate sorbents were prepared by impregnation- precipitation method. The crystal structures and morphologies were characterized by XRD and SEM, respectively. The CO2 absorption performance was studied by a thermogravimetric analyzer. The results indicated that the adsorbing capacity of kaolin-Li4SiO4 was higher than SiO2-Li4SiO4 at 350-700℃ in comparison with Li4SiO4 prepared with commercial SiO2. The high purity Li4SiO4 can be prepared by the impregnation-precipitation method successfully. The maximum adsorption of Li4SiO4 made by impregnation-precipitation method got up to 35.7% (mass) (704℃), which was 5.9% (mass) higher than Li4SiO4 made by solid method. The CO2 chemisorption produced directly over the Li4SiO4 particles was the limiting step of the whole reaction process when the temperature was lower than 600℃. The CO2 chemisorption process controlled by diffusion process was the limiting step of the whole reaction process when the temperature was higher than 650℃. The lithium diffusion rate of samples made by impregnation-precipitation method was nearly double for samples made by solid method. The rate of CO2 chemisorption produced directly over the Li4SiO4 particles made by impregnation-precipitation method was higher.

    Investigation of formation of bicarbonate in tertiary amines using 13C NMR technique
    ZHANG Rui, LI Moxia, LUO Xiao, LIANG Zhiwu
    2015, 66(9):  3719-3725.  doi:10.11949/j.issn.0438-1157.20150898
    Abstract ( 262 )   PDF (546KB) ( 445 )  
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    The amount of bicarbonate is a very important factor for energy consumption in solvent regeneration in CO2 capture process. More bicarbonate in rich amines will lead to lower energy cost in CO2 desorption process. To get a preciously knowledge of the formation of bicarbonate in tertiary amines for design a better absorbent for CO2 capture, a series of tertiary amines such as N-diethylethanolamine (DEEA),1-dimethylamino-2-propanol (1DMA2P), 1-diethylamino-2-propanol (1DEA2P), 3-dimethyl-amino-1-propanol (3DMA1P), N-methyldiethanolamine (MDEA), dimethylmonoethanolamine (DMMEA) and triethanolamine (TEA) with various CO2 loading at 1 mol·L-1 were investigated using 13C NMR technology at 293.15 K. The amount of bicarbonate was calculated by the chemical shift of bicarboante/carboante in 13C NMR spectra. The results showed that the order of the amount of bicarbonate in those tertiary amines is DMMEA > MDEA > 3DMA1P > 1DMA2P > TEA > DEEA > 1DEA2P. Considering the effects of electron density of nitrogen atom (N) and the steric hinderance in those tertiary amines to the formation of bicarbonate in those aqueous tertiary amines solution, it can be concluded that 1) the aqueous 3DMA1P solution produced more bicarbonate compared to DMMEA for its nearer distance of OH to N; 2) the less hydroxyalkyl and one more methyl in amine molecular structure connected to N in MDEA compared to TEA led to more bicarbonate generation; 3) a smaller alkyl connected to N in DMMEA molecular structure compare to DEEA resulted in more bicarbonate was generated in aqueous DMMEA solution; and 4) one more methyl branch existed in 1DMA2P and 1DEA2P molecular structures compared to 3DMA1P and DEEA, respectively, leading to less bicarbonate generation.

    Adsorption of cadmium and lead ions onto regenerated lignin from pretreatment liquid of rapeseed stalk
    DU Ruoyu, LIU Wei, XU Binbin, WANG Xiaoping, HE Youzhou, ZHENG Xuxu
    2015, 66(9):  3726-3732.  doi:10.11949/j.issn.0438-1157.20150832
    Abstract ( 237 )   PDF (862KB) ( 303 )  
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    Acid-insoluble lignin solids were regenerated from the organic-acid pretreatment waste liquor of rapeseed stalk and were used for the adsorption of cadmium and lead ions from the artificial waste liquor. The influence of regeneration strategy, crystallinity, surface area and functional group content on the adsorption efficiency were studied in this paper. The results indicated that these two types regenerated lignins can effectively adsorb Cd2+, Pb2+ ions from artificial waste liquor and the content of functional group plays an key factor. In addition, the adsorbability of both two types of lignins is larger for Cd2+ ions than for Pb2+ ions.

    Influence of coal ash on methane cracking
    WEI Ling, TAN Yisheng, HAN Yizhuo, ZHAO Jiantao
    2015, 66(9):  3733-3738.  doi:10.11949/j.issn.0438-1157.20150872
    Abstract ( 225 )   PDF (2873KB) ( 367 )  
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    Using coal char, de-ashed coal char, coal ash and quartz as catalysts, cracking of methane is studied in a fixed bed reactor at 1123 K and atmospheric pressure. Methane conversion and hydrogen yield over fresh and de-ashed coal chars show certain difference. The initial methane conversion of 9.81% and hydrogen yield of 8.14% is achieved at 1123 K over coal ash. The results show that coal ash is of certain catalytic activity for methane cracking. The conversion and hydrogen yield over coal char decrease gradually with the reaction time, indicating the deactivation of coal char. Lignite char and de-ashed char before and after reaction were characterized by using scanning electron microscope and specific surface area determinator. The results shows that the surface area and micro-pore volume of coal chars decrease and average pore diameter increases after methane decomposition reaction, implying that the micro-pore could be blocking by deposition of carbon formed in methane cracking, and the part surface of coal char has been covered by carbon of deposition, which makes catalytic activity of coal char decrease gradually.

    Experimental studies on sorption and desorption performance of CO2 by N,N-diethylethanolamine (DEEA) solution
    GAO Hongxia, LIU Sen, XU Bin, LIANG Zhiwu
    2015, 66(9):  3739-3745.  doi:10.11949/j.issn.0438-1157.20150906
    Abstract ( 226 )   PDF (636KB) ( 414 )  
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    The major drawback of using amine for carbon dioxide (CO2) capture is the contradiction between lower regeneration heat duty and high CO2 absorption rate. One way to overcome this problem is to develop an alternative absorbent with improved performance of sorption and desorption CO2, which can make energy consumption decrease. A quick method was used for selecting potential solvent systems for CO2 capture by experimental study in this paper. The analysis and comparison were made based on CO2 loading during sorption and desorption, the absorption/stripping rate, cycling capacity, relative heat consumption and so on. It is demonstrated that aqueous N,N-diethylethanolamine(DEEA) solution is of better absorption/stripping performance for CO2 capture, which can be presented in terms of equilibrium solubility, overall mass transfer coefficient(KGaV) and regeneration heat consumption, and these parameters were experimentally measured with relevant setup. The results show that the equilibrium solubility of CO2 in DEEA solution increases with rising of CO2 partial pressure and decreases with the increase of solution concentration; the KGaV increases with rising of liquid temperature and energy consumption; and the regeneration heat duty decreases with lean CO2 loading and increases with rich CO2 loading. Due to the high performance of DEEA, it could be a promising alternative solvent for CO2 capture.

    Adsorption and photocatalytic degradation of dye by N-doped TiO2/chitosan composited films
    CHEN Jianxin, ZHANG Na, LI Yinhui, LI Ruijuan
    2015, 66(9):  3746-3752.  doi:10.11949/j.issn.0438-1157.20150883
    Abstract ( 303 )   PDF (1712KB) ( 374 )  
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    A novel N-doped TiO2/Chitosan (CS) composited film, as a promising alternative material, was prepared, and could be more potential compared with tradition materials for treating wastewater. When this material, N-doped TiO2/CS film, was used for removing Methyl Orange (MO) under simulated solar light irradiation, about 99% of total MO removal was achieved due to the combination effect of photo-degradation and adsorption processes. N-doped TiO2/CS photo-catalyst was characterized by using X-ray diffraction (XRD), scanning electron microscopy (SEM), and Fourier transform infrared spectroscopy (FT-IR) analysis. The results indicate that there exist the reactive groups NH2, OH on the N-doped TiO2 film, and their contents in the prepared photo-catalyst are responsible for the photo-degradation and adsorption effect, which was confirmed by FT-IR. Hence, it is possible that using N-doped TiO2/ CS film as a simple method for removal of the pollutants in wastewater.

    Enzyme degumming process of banana pseudostem fibers andcharacterization of degummed fibers
    XU Shuying, TAN Wei, ZHANG Yucang
    2015, 66(9):  3753-3761.  doi:10.11949/j.issn.0438-1157.20150998
    Abstract ( 370 )   PDF (5073KB) ( 376 )  
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    In order to utilize the banana pseudostems, a rich biomass resource in Hainan, the fibers were extracted from banana pseudostem by enzyme treatment. In this work, the better process conditions of frequency and temperature in ultrasonic pretreatment were determined, and two enzymes, hemicellulase and pectinase, were used to remove pectin and hemicelluloses, and to loose the compact structure of fibers, respectively. The better degummed process conditions of the concentration of these two enzymes, reaction temperature and pH value in enzyme process were optimized in terms of degummed rate. The optimum parameters were determined as: the concentration of hemicellulase 0.004 g·ml-1, reaction temperature 50℃, pH value 5.5, concentration of pectinase 0.003 g·ml-1, reaction temperature 55℃ and pH value 6.0. Chemical characterization of the banana pseudostem fibers confirmed that the cellulose content was increased from 60% to 65% due to the application of enzyme treatments. The physicochemical properties of enzyme treated banana pseudostem fibers were analyzed by using the fourier transformed infrared spectroscopy (FTIR), X-ray diffraction (XRD) and scanning electron microscopy (SEM). The tensile properties of enzyme treated banana pseudostem fibers were also investigated. The FTIR and XRD analyses of the enzyme treated banana pseudostem fibers showed an obvious reduction in amount of noncellulosic substances with a crystallinity index of 66.4%. Surface morphological studies using SEM revealed that the enzyme treated banana pseudostem fibers had a rougher surface with a lot of little pectin substance and exhibited brittle fracture. The tensile tests revealed that the tensile strength was about 118.48 MPa with Young's modulus of 15.15 GPa and elongation at break of 0.67%.

    Study on crystallization of poly (L-lactic acid) nucleated with p-tert-butylcalix[4]arene inclusion complex
    SHI Yaoqi, XIN Zhong, LU Yingyin, ZHOU Shuai
    2015, 66(9):  3762-3768.  doi:10.11949/j.issn.0438-1157.20150798
    Abstract ( 318 )   PDF (7249KB) ( 314 )  
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    In this paper, four inclusion complexes were obtained by recrystallizing p-tert-butylcalix[4]arene (tBC4) from toluene, o-xylene, m-xylene and p-xylene. Then, the effects of tBC4 inclusion complexes on crystallization behavior of poly (L-lactic acid) (PLLA) were investigated with differential scanning calorimeter and polarized optical microscopy. The results showed that the crystallization peak temperature of PLLA nucleated by tBC4 inclusion complexes increased 7℃, which indicated that these compounds owned the nucleation ability for PLLA. After suffering high temperature, crystal structures of four inclusion complexes reverted to nearly the same. Therefore, all these inclusion complexes showed the same nucleation ability. Crystallization morphologies of PLLA and nucleated PLLA were studied by means of polarizing optical microscopy, indicating that the addition of nucleating agent can decrease PLLA spherulite size without changing its growth pattern.

    Fabrication of high performance ZrO2-TiO2 NF membranes via a modified colloidal sol-gel process
    LU Yawei, CHEN Xianfu, WEN Juanjuan, QIU Minghui, FAN Yiqun
    2015, 66(9):  3769-3775.  doi:10.11949/j.issn.0438-1157.20150936
    Abstract ( 219 )   PDF (4031KB) ( 403 )  
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    The optimized ZrO2-TiO2 composite colloidal sols with an average particle size of 3 nm were successfully synthesized via a modified colloidal sol-gel process by using water as solvent. Tubular α-Al2O3 membranes with a mean pore size of 5 nm were used as the intermediate layers. Defect-free ZrO2-TiO2 NF membranes were then fabricated on the interlayer surface via a dip-coating method. The ZrO2-TiO2 NF membranes with an average toplayer thickness of 200 nm showed the relatively high pure water permeability of about 23 L·m-2·h-1·(0.1 MPa)-1 and low MWCO of about 600. Meanwhile, the ZrO2-TiO2 NF membranes indicated the high retention rates for Co2+, Sr2+ and Cs+ of 99.6%, 99.2% and 75.5% at the condition of low salts concentration, pH 3 and the transmembrane pressure of 0.9 MPa, respectively.

    Preparation of WC/MMT nanocomposite and its electrocatalytic activityfor p-nitrophenol
    LI Guohua, YANG Wei, TONG Mingxing, ZHENG Xiang
    2015, 66(9):  3776-3781.  doi:10.11949/j.issn.0438-1157.20150779
    Abstract ( 305 )   PDF (4684KB) ( 390 )  
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    Tungsten carbide and montmorillonite (MMT) nanocomposite was prepared through combining an impregnation approach with a reduction-carbonization method using exfoliated MMT as a support. The samples were characterized by X-ray diffraction, scanning electron microscope and transmission electron microscope. The results showed that the structure of exfoliated MMT was lamellar. The thickness of exfoliated MMT layer was between 10 nm and 15 nm. The edge of exfoliated MMT layer rolled and the interplane distance of exfoliated MMT were enlarged. The crystal phase of the sample was composed of monotungsten carbide (WC), bitungsten carbide (W2C) and MMT. The particles of tungsten carbide were distributed on the surface of exfoliated MMT. The electrochemical reduction activity of the nanocomposite for p-nitrophenol (PNP) was tested by cyclic voltammetry (CV) in acidic solution. It was found that WC/MMT nanocomposite was electrocatalytic active to PNP and its electrocatalytic activity was stable. This implied that the exfoliated MMT was one of the excellent composite carriers to improve the electrocatalytic property of WC, which can be used in other catalysts.

    Morphology-controlled synthesis of mesoporous alumina dependenton triblock copolymer
    GU Ling, CUI Xili, TANG Shaokun, ZHANG Xiangwen
    2015, 66(9):  3782-3787.  doi:10.11949/j.issn.0438-1157.20150843
    Abstract ( 225 )   PDF (1509KB) ( 322 )  
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    In this study, sheet-like and rod-shaped mesoporous aluminas were synthesized with a triblock copolymer as the structure-directing agent via hydrothermal method. X-ray diffraction, transmission electronic microscopy and nitrogen adsorption and desorption were performed to determine the crystalline phase, morphology and pore structure of the aluminas. It was found that the morphologies, mesostructures and pore parameters of aluminas can be altered by the introduction of the triblock copolymer. The adsorption of the triblock copolymer on the surface of the alumina gels induced the oriented growth of the crystallines, resulting in the formation of final aluminas nanorods.

    β-Nucleation effects induced by long chain branching polypropylene
    ZHOU Shuai, XIN Zhong, WANG Weixia, ZHAO Shicheng, SHI Yaoqi
    2015, 66(9):  3788-3794.  doi:10.11949/j.issn.0438-1157.20150846
    Abstract ( 207 )   PDF (3899KB) ( 486 )  
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    Taking advantages of long chain branching polypropylene based on grafting vinyl polydimethylsiloxane/ styrene (PP-g-VS/St) can generate β-crystal polypropylene under shear and high cooling rate condition, PP-g-VS/St was used as a polymeric β-nucleating agent for isotactic polypropylene (iPP) under injection modeling processing and its effects on the crystallization temperature, crystal structure and mechanical properties of iPP were investigated. The results indicated that the crystallization temperature, β-crystal relative content and mechanical properties of modified iPP were improved as increasing the content of PP-g-VS/St. The crystallization temperature of modified iPP with 50% (mass) PP-g-VS/St increased by 10℃ compared with that of virgin iPP and the β-crystal relative content reached 32.8%. The impact strength, flexural modulus and tensile strength were enhanced by 355.3%, 53.8% and 15.9%, respectively, compared with those of virgin iPP. These results may provide a new method to design polymeric β-nucleating agent for iPP.

    Synthesis and properties of organic/inorganic superabsorbent resin
    HAN Yueyun, CAO Qiling, HUA Quanxian, LU Leiming, TANG Jianwei, LIU Yong
    2015, 66(9):  3795-3800.  doi:10.11949/j.issn.0438-1157.20151005
    Abstract ( 249 )   PDF (1152KB) ( 313 )  
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    One superabsorbent resin (SAR) was synthesized by solution copolymerization with starch, kaolin, acrylic acid as the main raw materials. The influences of mass ratio of monomers to starch, degree of neutralization of acrylic acid, amount of cross-linking agent and initiator on the absorbency were studied to optimize the preparation condition. The absorbencies of the best sample thus synthesized can be up to 1195.4 g·g-1 in distilled water and 90.1 g·g-1 in saline solution (0.9%,mass). The results of Fourier Transform Infrared Spectroscopy (FTIR) showed that OH in kaolin participates in the polymerization reaction, enhancing the crosslinking extent and increasing the absorbency of sample. SEM results revealed that the SAR sample had the multi-porous and layered structure. The experiments of thermal stability indicated that SAR synthesized in this paper had the stable absorbency under 100℃.

    Preparation of match-like carbon nanotube and its growth mechanism
    LI Guohua, SUN Haibiao, YU Yang, XIE Weimiao
    2015, 66(9):  3801-3807.  doi:10.11949/j.issn.0438-1157.20150780
    Abstract ( 222 )   PDF (13003KB) ( 479 )  
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    Tungsten trioxide nanorod was prepared by a hydrothermal method using sodium tungstate as tungsten source and sodium chloride as an inducer. The nanorod was coated with carbon by a hydrothermal reaction once again and using glucose as a carbon source. Match-like carbon nanotube was fabricated by reaction under a mixed gas of H2 and CH4 with a volume ratio of H2 to CH4 of 1:4. The crystal phase, morphology, microstructure and chemical elements of the samples were characterized and analyzed by X-ray diffraction, scanning electron microscope, transmission electron microscope and X-ray energy dispersion spectrum. The results showed that the sample was consisted of carbon nanotube and tungsten carbide (WC). The morphology of the carbon nanotube was of match-like with a length between 0.5 μm and 1.0 μm, and a diameter around 100 nm. WC particles laid in the inner space of the carbon nanotube and the inner diameter of the nanotube was depended on the diameter of WC particle. These implied that WC particle took a catalytic role during the growth of the carbon nanotube.