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Table of Content
05 January 2023, Volume 74 Issue 1
    Reviews and monographs
    Progress for green chemicals production by microbial manufacturing
    Haoran BI, Yang ZHANG, Kai WANG, Chenchen XU, Yiying HUO, Biqiang CHEN, Tianwei TAN
    2023, 74(1):  1-13.  doi:10.11949/0438-1157.20221322
    Abstract ( 1070 )   HTML ( 84)   PDF (776KB) ( 640 )  
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    Microbial manufacturing uses renewable raw materials such as biomass and carbon dioxide for green production of chemicals, which shows a huge potential for reducing carbon dioxide emissions and is an important way to promote the goal of “carbon neutrality”. One of its core contents is the high-efficiency microbial cell factory design and construction. The research progress of metabolic flow analysis and metabolic pathway prediction based on genome-scale metabolic network model is reviewed. Novel genome editing tools are introduced to facilitate the efficient development of microbial cell factories and metabolic regulation strategies are summarized to enhance the productivity of microbial cell factories. In addition, the application of key microbial manufacturing technologies in third-generation manufacturing is outlined. Finally, the future applications and development directions of microbial manufacturing in chemical production are foreseen.

    Artificial intelligence for accelerating polymer design: recent advances and future perspectives
    Tianhang ZHOU, Xingying LAN, Chunming XU
    2023, 74(1):  14-28.  doi:10.11949/0438-1157.20221077
    Abstract ( 789 )   HTML ( 41)   PDF (4081KB) ( 659 )  
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    Due to the enormous chemical and configurational space, the optimal design of candidates for the next-generation soft materials is still a challenging task. It is cumbersome to conduct trial-and-error research using high-throughput computations or experiments to evaluate the properties of a large number of materials and select the best candidates for future investigations. Using artificial intelligence approaches in combination with computer simulations and experiments, researchers are able to reliably predict properties of materials over a vast structural and property space, breaking the traditional model of “empirically guided experiments” and gradually overcoming various bottlenecks in the process of the polymer design. This review begins with a historical look at the difficulties in polymer engineering over the preceding decades. The concept of data-driven techniques is then given and examined in detail, along with how they are used in polymer design. The following section highlights some noteworthy developments in identifying novel polymers with specific characteristics using data-driven approaches. In conclusion, this review provides a synopsis of recent tendencies and outlines the opportunities for intelligent design in polymer engineering. Artificial intelligence, rapid computational simulation, and the availability of enormous amounts of open-source homogeneous data combined with experiments will revolutionize polymer research and accelerate the industrial application of designed polymeric materials. Finally, the current industry development trend is summarized, and the large-scale application prospects of intelligent design in the research of new polymers are prospected.

    Optimization strategy for producing carbon based fuels by photocatalytic CO2 reduction
    Feng WANG, Shunxin ZHANG, Fangbo YU, Ya LIU, Liejin GUO
    2023, 74(1):  29-44.  doi:10.11949/0438-1157.20221120
    Abstract ( 934 )   HTML ( 52)   PDF (2691KB) ( 490 )  
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    The photocatalytic CO2 reduction to hydrocarbon fuel technology is directly driven by solar energy and converts CO2 into directly usable chemicals. It is a transformative technology to help carbon peak and carbon neutrality. The efficient and low-cost operation of this technology is determined by light absorption and utilization, the morphology and structure of photocatalysts, the interfacial catalytic reaction, and mass transfer etc. In general, the internal energy and mass transfer of this technology is a multi-scale spatio-temporal process and needs to be studied by using a multi-physics field coupling model from both theoretical and application aspects. In this paper, the fundamental theory and the state-of-the-art are summarized. Also, we present the development tendency of photocatalytic CO2 reduction technology from aspects of light absorption expansion and utilization, photogenerated carrier separation enhancement, oxidation/reduction half-reaction optimization, and mass transfer enhancement. Then we discuss the matching strategy between energy transfer and chemical reaction within the whole process, which provide the way for reducing the energy loss, promoting performance, and future industrial application of solar-driven CO2 reduction.

    Application of the redox cascade systems with coenzyme self-cycling in biocatalytic processes: opportunities and challenges
    Zhuotao TAN, Siyu QI, Mengjiao XU, Jie DAI, Chenjie ZHU, Hanjie YING
    2023, 74(1):  45-59.  doi:10.11949/0438-1157.20221075
    Abstract ( 414 )   HTML ( 26)   PDF (6091KB) ( 325 )  
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    Oxidoreductases are one of the most widely used enzymes in biocatalysis process. It can catalyze under mild conditions with high selectivity and play an important role in chemical, pharmaceutical, agriculture and so on. Most oxidoreductase-catalyzed reactions require the nicotinamide cofactor. Due to the high cost of nicotinamide cofactor, large amount of usage is not practical for industrial applications. Thus, it is of great significance to develop efficient and economical cofactor regeneration strategies for the industrial application of oxidoreductases. Among the commonly used cofactor regeneration methods, enzymatic method is frequently used based on its high efficiency and environmental friendliness. Redox-neutral system is a special strategy for enzymatic regeneration of nicotinamide cofactors. It can be combined with multi-enzyme cascade catalysis to self-sufficiently complete the regeneration of nicotinamide cofactors without adding any co-substrates. It has the advantages of few by-products and high atomic economy compared with conventional enzymatic regeneration methods. In this review, the redox-neutral system is divided into four categories to discuss according to the sequence of multi-enzymatic cascade reactions. Based on alcohol/aldehyde dehydrogenase, the opportunities and challenges of the redox-neutral system in biocatalysis process are reviewed, which can provide positive ideas for designing a more efficient redox-neutral systems in the further.

    Research progress of loop heat pipes for heat dissipation of high-heat-flux electronic devices
    Jinjia WEI, Lei LIU, Xiaoping YANG
    2023, 74(1):  60-73.  doi:10.11949/0438-1157.20221056
    Abstract ( 668 )   HTML ( 34)   PDF (3904KB) ( 316 )  
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    Loop heat pipe is an efficient two-phase heat transfer device, which has great prospects in the field of heat dissipation of high-heat-flux electronic devices. This paper introduces the three current bottleneck problems of the plate loop heat pipe, namely, the limit heat flux cannot meet the needs of some high-power devices, the temperature fluctuation problem, the failure to start at low power and the problem of temperature overshoot. The reasons for these problems are analyzed and the solutions proposed by researchers in the past decade are summarized, which includes the optimization of wick, the improvement of working fluid and the modification of loop heat pipe structure. The applications of loop heat pipes are also introduced. Finally, the research status of loop heat pipes with flat evaporator is summarized, and further research directions are prospected to improve the comprehensive performance and realize the commercial application of loop heat pipes.

    Preliminary study on mechanism of transfer in confined space: description of confined transfer resistance based on confined fluid state
    Yao QIN, Yumeng ZHANG, Xueling PAN, Wenqiang WANG, Zhengxing DAI, Yudan ZHU, Xiaohua LU
    2023, 74(1):  74-85.  doi:10.11949/0438-1157.20221080
    Abstract ( 841 )   HTML ( 27)   PDF (1473KB) ( 423 )  
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    Molecule transfer in the nanoconfined space is a common issue in the modern chemical process. However, surface wettability and confined degree in nanoconfined space lead to the effect of asymmetry of the molecular interaction. Such symmetric interaction induces the inhomogeneous and further causes the unavailable of the classical transfer theory. The lack of the transfer theory oriented to the limit can no longer meet the needs of the development of modern industry. This paper summarizes the research work of our team and the frontier of confined transport, and analyzes it based on statistical mechanics and non-equilibrium thermodynamic methods. It is found that the frontier research covers three perspectives. Namely, molecular interaction determines the abnormal fluid state in new free degrees, the abnormal fluid state-dependent fluid transfer phenomenon further decides the confined fluid resistance of fluid transfer. Based on three perspectives, the primary theory of confined transfer resistance is concluded. Furthermore, the primary theory of confined transfer resistance is used to analyze hot research in nanoconfinement conducted by advanced experimental and theoretical works. Finally, this work proposed that combining three perspectives, in terms of the fluid state in the space, may give a framework to develop the nanoconfined transfer theory for guiding the development of modern chemical engineering.

    Heavy oil to chemicals: multi-stage downer catalytic pyrolysis
    Hao XIONG, Xiaoyu LIANG, Chenxi ZHANG, Haolong BAI, Xiaoyu FAN, Fei WEI
    2023, 74(1):  86-104.  doi:10.11949/0438-1157.20221188
    Abstract ( 834 )   HTML ( 39)   PDF (5304KB) ( 293 )  
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    High yield of petrochemicals, such as light olefins and aromatics, is an important way for low-carbon utilization of petroleum. Based on China’s energy structure and technological advantages in the field of catalytic cracking, the direct production of light olefins and aromatics from heavy feedstock oil under the confinement of molecular sieves is an important development direction of China’s oil refining industry. It poses great challenges to the design of multi-phase reactors. Counter-current interaction between feed-oil and deep-cracking catalysts under high severity should be achieved to prevent preferential adsorption of heavy aromatics, reduce diffusion resistance in zeolitic nanopores, and boost deep cracking of short-chain alkanes. Millisecond residence time and plug-flow residence time distribution should be obtained to inhibit secondary reactions and reduce dry gas and coke production. This review focuses on the progress of discrete transport, reaction, and deactivation processes in the catalytic cracking of heavy oil directly to chemicals, as well as the progress of gas-solid heterogeneous reaction engineering and other related fields. The latest research work on the discrete adsorption-diffusion phenomenon and host-guest interactions of small molecules in zeolites are introduced, and it is proposed to use facet-selective nanosized zeolites with high resistance to coke formation and gas-solid counter-current contact plug flow reactors to overcome the above challenges. Finally, the multi-stage downer catalytic pyrolysis (MDCPTM) developed by Tsinghua University is introduced, which uses multi-stage downers in series while achieving both millisecond-level plug-flow within one stage and counter-current gas-solids interaction between each stage. In the 1 kg/h pilot plant, MDCPTM can gain excellent production distribution [51.54% (mass) yield of light olefins and 80.78% (mass) selectivity of BTEX in gasoline]. With MDCPTM as the core unit, the process, i.e., heavy oil to chemicals (HOTC), is reported where the yield of the total chemicals can be up to 75% (mass), with carbon emission reduced by more than 70% compared with existing technologies.

    Research progress of porous ceramic membranes based on 3D printing technologies
    Xianfu CHEN, Dongyu WANG, Yiqun FAN, Weihong XING, Xu QIAO
    2023, 74(1):  105-115.  doi:10.11949/0438-1157.20220994
    Abstract ( 433 )   HTML ( 18)   PDF (719KB) ( 215 )  
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    High-performance membranes are the “chip” of membrane separation technology, and the development of new and efficient preparation methods is an important research direction in the field of membrane separation. 3D printing technology based on digital model has shown excellent flexibility in the precise construction of complex structures. In recent years, the application of 3D printing technologies in the development of high-performance membranes has received extensive and continues attention. In this paper, the research progress of 3D printing technology for porous ceramic membranes is reviewed from the aspects of preparation methods and performance enhancement. The challenges of 3D printing technology faced by porous ceramic membranes are discussed, and their potential development directions are also prospected.

    Self-propulsion of enzyme and enzyme-induced micro-/nanomotor
    Yang HU, Yan SUN
    2023, 74(1):  116-132.  doi:10.11949/0438-1157.20221053
    Abstract ( 510 )   HTML ( 24)   PDF (4679KB) ( 245 )  
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    Enzymes that play an essential role in life activities as biocatalysts have been reported to exhibit enhanced diffusion during the bioconversion of substrate to product. This self-driven diffusion-enhanced phenomenon provides a new angle to study enzymes: enzyme molecular motors (EMMs). Inspired by natural biomolecular motors, EMM was used as the “engine” to fabricate various enzyme-powered micro-/nanomotors (EMNMs) and micropumps (EMPs), converting chemical energy to mechanical energy and propelling movement at the micro-/nanoscale. Through ingenious design, EMNMs have been functionalized for accomplishing various tasks, attracting more and more attention. However, the precise movement mechanisms of EMM and EMNM are still under debate in current literature. The effects of size, structure, and enzyme properties on the micro-/nanoscale movement are still unclear. These limit the investigation of the application of EMNM and EMP. This article is devoted to reviewing the self-propelled molecular movement of EMM, as well as the movement of EMNM and EMP using an enzyme as the “engine”. First, the condition for realizing the molecular and micro-/nanoscale movement in the ultralow Reynolds number regime, the self-propulsion and chemotaxis of EMM, and the movement mechanism of the reported EMM were introduced. Then, the classification of the various EMNM and EMP are discussed, emphasizing the approach of enzyme-powered microscale movement and the potential application of EMNM. Finally, major challenges in the development of enzyme-powered devices are addressed and future research into this crucial field is proposed.

    High temperature heat pump: cycle configurations, working fluids and application potentials
    Yixiu DONG, Ruzhu WANG
    2023, 74(1):  133-144.  doi:10.11949/0438-1157.20220995
    Abstract ( 1088 )   HTML ( 46)   PDF (2406KB) ( 650 )  
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    The unreasonable energy consumption will lead to the shortage of resource and the damage of environment. Among large manufacturing countries, industry is the sector with the largest energy consumption, and its energy use transformation has received extensive attention. The high temperature heat pump which can meet the industrial heat demand is essential to promote the clean and electrification of industrial energy consumption. The establishment of high temperature heat pump mainly focuses on two aspects: cycle configuration and working fluid. In cycle configuration, compression, absorption, and hybrid compression-absorption high temperature heat pumps are sorted out; the working temperature range of the heat pump in each study is extracted; the heat source temperature and temperature lift in different cycle configurations are summarized; and a selection guideline of cycle configurations according to the condition of heat source and users' temperature demand is provided. As for working fluids, their evolution process is sorted out; the suitable working temperature region is analyzed according to their characteristics, and the screening principles of working fluids are summarized. Finally, the application scenarios of high temperature heat pump are prospected. Besides being used in industrial processes, it can also be involved in Carnot batteries to achieve the storage and conversion of electricity-heat-electricity.

    Research progresses on In2O3 and In2O3 supported metal catalysts for CO2 hydrogenation to methanol
    Chenyang SHEN, Kaihang SUN, Yueping ZHANG, Changjun LIU
    2023, 74(1):  145-156.  doi:10.11949/0438-1157.20221072
    Abstract ( 842 )   HTML ( 45)   PDF (2781KB) ( 477 )  
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    The conversion and utilization of carbon dioxide plays important roles in carbon neutrality. Among various options for CO2 utilization, hydrogenation of CO2 to methanol attracts increasing attentions because methanol is an important chemical intermediate and also excellent alternative liquid fuel. A highly active catalyst with high methanol selectivity is the key for the potential application of CO2 hydrogenation to methanol. With their high activity and high methanol selectivity, In2O3 and In2O3 supported metal catalysts have recently received broad interests. In2O3 has strong interaction with metal like gold, silver, platinum, palladium, ruthenium, rhodium, iridium, nickel and rhenium. The strong metal-In2O3 interaction can not only stabilize indium oxide, avoid over-reduction of indium oxide, but also lead to the catalyst electronic structure changes, tuning the catalyst to be highly active for selective hydrogenation of CO2 to methanol. In2O3 for CO2 hydrogenation to methanol was found by the density functional theoretical study. Thus, In2O3 and the supported metal catalysts for CO2 hydrogenation are theoretically predictable and excellent model catalysts for studies of single atom catalyst, cluster and nanoparticle catalysts. The conversion route of the In2O3 and its supported catalysts is excellent for the definition of catalyst. These catalysts are important for fundamental studies and also for future applications.

    Research progress on dedust scheme of coupling centrifugal force field with moving bed filtration
    Yiping FAN, Chunxi LU
    2023, 74(1):  157-169.  doi:10.11949/0438-1157.20221079
    Abstract ( 279 )   HTML ( 10)   PDF (4339KB) ( 95 )  
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    The development of the gas-solids separator is crucial to the dust-collection for high-temperature flue gas. It was demonstrated that any separator with single-mechanism essentially cannot achieve a deep dedusting process. Therefore, coupling centrifugal separation and moving bed separation in the same equipment to achieve synergistic strengthening of the two separation mechanisms is undoubtedly a solution. The researches indicated that the moving/flow of the gas, the collecting particles and the dusts in both its outer cyclone shell and built-in moving bed present distinct characteristics comparing those in the commonly used cyclone separator and moving bed. It was also found that the coupling separator had the self-cleaning function by analyzing the measured pressure drop-time response curves. The collecting efficiency of the coupling separator reaches above 95% for fine dusts. The dusts larger than 10 μm are generally caught by the cyclone shell while those smaller than 10 μm are collected by the built-in granular bed. It was shown that the gas-solid separation was corporately strengthened by two different mechanisms in one equipment. However, the self-cleaning function and the collecting efficiency are actually a pair of contradictions. Moreover, the tentative optimal results showed that the coupling separator could be further improved in the future.

    Kinetic regulation strategies in lithium-sulfur batteries
    Xun JIAO, Cheng TONG, Cunpu LI, Zidong WEI
    2023, 74(1):  170-191.  doi:10.11949/0438-1157.20221071
    Abstract ( 341 )   HTML ( 14)   PDF (13347KB) ( 299 )  
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    Lithium-sulfur (Li-S) batteries are expected to be one of the candidates for next-generation high-energy-density batteries because of their ultra-high theoretical energy density (2600 Wh·kg-1). However, it suffers from low sulfur utilization, rapid capacity fading, and the “lost effect” of lithium polysulfides (LiPSs). These problems make the reaction kinetics of Li-S batteries sluggish, severely limiting their practical applications. Methods such as physical confinement and chemical adsorption can accelerate the redox reaction between sulfur, LiPSs, and Li2S, reduce the loss of LiPSs, and accelerate the kinetic process, which enable the battery with high energy density and long-cycle stability. Based on the overall electrochemical reaction process, this article reviews how materials used in recent years can facilitate the kinetic process, prevent the loss of LiPSs, and evaluate the corresponding strategies. The purpose of this review is to help guide the rational design of improved battery kinetics and the practical application of Li-S batteries.

    Research process of porous ion conducting membranes for flow batteries
    Wenjing LU, Xianfeng LI
    2023, 74(1):  192-204.  doi:10.11949/0438-1157.20221314
    Abstract ( 502 )   HTML ( 28)   PDF (1703KB) ( 376 )  
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    Flow battery has outstanding features of high safety, high cost performance, long lifespan and great environmental friendliness, very suited for large-scale energy storage. A typical flow battery is composed of the electrodes, the membrane, the electrolytes and so forth. Among them, a membrane plays the role in avoiding the crossover of active species in different electrolytes while conducting charge carriers to form a complete electrical circuit simultaneously. Consequently, the membrane properties and price exert significant effects on the performance and cost of flow batteries. However, the commonly used commercial per-fluorinated sulfonated ion exchange membranes have low selectivity and high cost, while the highly selective and low-cost non-fluorinated ion exchange membranes have poor chemical stability because of the existence of ion exchange groups. As a result, porous ion conducting membrane without ion exchange groups was introduced into flow batteries, which was based on the “ion sieving conducting” mechanism to avoid the transference of active species and conduct charge carriers at the same time. Consequently, porous ion conducting membranes generally have high stability, high selectivity and high conductivity. Moreover, up to now, many modifying strategies have been proposed to tune the structure and optimize the performance of porous ion conducting membranes. The large-scale quantity production of high-performance and low-cost porous ion conducting membranes has also been achieved. In this review, various modifying strategies of porous ion conducting membranes will be overviewed based on their research and development in flow batteries. Therefore, this review will provide significant theoretical instructions to further tune the structure and optimize the performance of porous ion conducting membranes in flow batteries.

    Advances in chemical-looping oxidative dehydrogenation of light alkanes
    Jiachen SUN, Chunlei PEI, Sai CHEN, Zhijian ZHAO, Shengbao HE, Jinlong GONG
    2023, 74(1):  205-223.  doi:10.11949/0438-1157.20221311
    Abstract ( 743 )   HTML ( 42)   PDF (5217KB) ( 354 )  
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    The production capacity of light olefins can reflect the technology level of the chemical industry. With the growing market demand for light olefins, novel and efficient light olefin production processes have attracted extensive attention. With chemical-looping light alkane oxidative dehydrogenation technology, through the reaction of lattice oxygen in the oxygen carrier and reactant molecules, the selective conversion of alkane molecules to olefin molecules can be realized, which can increase the yield of olefins and effectively reduce the process energy consumption and CO2 emission. This review analyzes the current research progress on the screening and theoretical design of oxygen carrier materials, the regulation mechanism of surface active sites and lattice oxygen transport in the bulk phase, and the optimization of reactors and processes for chemical-looping light alkane oxidative dehydrogenation technology. The future development trends of chemical-looping light alkane oxidative dehydrogenation technologies are systematically summarized to provide instructive perspectives for the advance of relevant technologies.

    Selective electrodialysis: opportunities and challenges
    Junying YAN, Huangying WANG, Ruirui LI, Rong FU, Chenxiao JIANG, Yaoming WANG, Tongwen XU
    2023, 74(1):  224-236.  doi:10.11949/0438-1157.20221073
    Abstract ( 625 )   HTML ( 27)   PDF (1200KB) ( 310 )  
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    Precise ion fractionation for the same charge but different valences is crucial to various industrial sectors, such as electrodialytic seawater salt production, brine refining in the chlor-alkali industry, lithium extraction from salt lakes, and waste acid and alkali recycling in the metallurgical industry. Selective electrodialysis (SED) enables the selective separation of various ions by replacing the anion- or cation-exchange membranes with mono/multivalent selective ion exchange membranes in the conventional electrodialysis stack. This paper introduces the separation mechanism of monovalent ion/divalent ion membrane and the preparation route in detail. Meanwhile, the commonly used membrane stack configuration and its working principle are also described. Moreover, the challenges of the SED, including the high investment cost, poor stability, and occurrence of concentration polarization on the membrane surface, are discussed. Finally, the perspective of SED technology is proposed from the aspects of the optimization of membrane stack configuration, the improvement of ion separation selectivity through various process integrations, and large-scale mono/divalent selective ion membrane fabrication.

    Research progress on the mass transfer process of CO2 absorption by amines in a packed column
    Xuqing WANG, Shenglin YAN, Litao ZHU, Xibao ZHANG, Zhenghong LUO
    2023, 74(1):  237-256.  doi:10.11949/0438-1157.20221076
    Abstract ( 845 )   HTML ( 54)   PDF (1405KB) ( 487 )  
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    Amine absorption of CO2 is a typical gas-liquid mass transfer and reaction process. As an important gas-liquid separation equipment in chemical production, packed columns have the advantages of high mass transfer efficiency, large production capacity, and large operation flexibility due to the high porosity of the packing layer. In this review, the mechanisms of CO2 absorption with amines and the gas-liquid mass transfer models are introduced. Besides, the effects of operating temperature, CO2 loading, CO2 partial pressure, inert gas flow rate, liquid flow rate and temperature, the type and concentration of amines, and packing types on the mass transfer process in CO2 absorption are summarized, based on the hydrodynamic properties of packed columns with low liquid holdup, low pressure drop in the packings and the operating characteristics with high gas velocity while fluids flooding. Finally, the directions of future studies are proposed, that in-depth research on gas-liquid mass transfer and reaction process in packed columns can be carried out from both experimental and simulation perspectives in terms of improving the mass transfer efficiency of packings and enhancing the amine absorption performance.

    Advances in the design, synthesis and application of porous liquids
    Guojia YU, Dongyu JIN, Zhiyong ZHOU, Fan ZHANG, Zhongqi REN
    2023, 74(1):  257-275.  doi:10.11949/0438-1157.20220955
    Abstract ( 504 )   HTML ( 29)   PDF (10308KB) ( 229 )  
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    Porous liquid is a new material with stable permanent cavity structure and fluidity that combines the advantages of solid-liquid two-phase, with excellent physical and chemical properties and broad application prospects. This paper reviews the research and development history of porous liquids, highlights the research advances in the design synthesis, physical characterization and mechanism simulation calculation of various types of porous liquids, analyzes the formation and mechanism of action of porous liquids, and introduces in detail the applications and progress of porous liquids in gas separation, chiralityinduction, extraction separation and catalysis. Finally, the future development direction of porous liquids is prospected.

    Progress in the mass production of single-atom catalysts
    Hao ZHANG, Ziyue WANG, Yujie CHENG, Xiaohui HE, Hongbing JI
    2023, 74(1):  276-289.  doi:10.11949/0438-1157.20221574
    Abstract ( 694 )   HTML ( 40)   PDF (9524KB) ( 415 )  
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    Single-atom catalysts (SACs) have the advantages of clear active sites (like homogeneous catalysts) and easy separation (like heterogeneous catalysts), which are regarded as the bridge between traditional homogeneous and heterogeneous catalysis. SACs exhibit excellent catalytic performance in a series of important reactions due to their high utilization of metal species and unique electronic/geometric structure, and have a great prospect of industrial application. The preparation scale of single-atom catalysts reported so far is still mostly limited to the gram or even milligram level, which is far from meeting the needs of future industrial applications. This review describes two typical synthesis strategies for large-scale preparation of SACs: batch type (e.g., pyrolysis, physical mixing, and gas migration) and continuous type (e.g., microencapsulation, precursor atomization, photochemical synthesis, two-stage microreactor, and electric field-assisted synthesis). It provides reference for industrial production and application of SACs.

    Progress of structure for carbon-fueled solid oxide fuel cells
    Xiang GUO, Jinshuo QIAO, Zhenhua WANG, Wang SUN, Kening SUN
    2023, 74(1):  290-302.  doi:10.11949/0438-1157.20221070
    Abstract ( 558 )   HTML ( 16)   PDF (2620KB) ( 205 )  
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    Direct carbon-fueled solid oxide fuel cells (DC-SOFC) are power generation device that directly converts the chemical energy of carbon fuel into electrical energy through an electrochemical process. It has excellent power generation efficiency, high fuel efficiency and low carbon emissions. However, solid fuels are less mobile than gas and liquid fuels. So, at present, enhancing the solid fuel transfer rate to promote effectively the anode reaction kinetics process, and how to add fuel efficiently and conveniently are the key problems for DC-SOFC. In this paper, the recent progresses of DC-SOFC structure research are reviewed in terms of fuel cell macrostructure and anode micromorphology, and the key problems and development direction of carbon solid oxide fuel cell are also discussed.

    Advances in two-dimensional graphene oxide membrane for ion selective transport
    Houchuan YU, Teng REN, Ning ZHANG, Xiaobin JIANG, Yan DAI, Xiaopeng ZHANG, Junjiang BAO, Gaohong HE
    2023, 74(1):  303-312.  doi:10.11949/0438-1157.20221074
    Abstract ( 348 )   HTML ( 12)   PDF (2553KB) ( 579 )  
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    Membrane separation technology has become an important method for ion separation due to its advantages of low energy consumption and high selectivity. Graphene oxide (GO) exhibits single-atom thickness with fruitful oxygen-containing groups. The GO laminar membrane shows precise ion-sieving selectivity. This review systematically presents the progress of GO membranes for selective transport of ions. The performance of GO membranes is optimized by laminar structure regulation and charge modification. For laminar structure regulation, the methods of partial reduction, physical intercalation and chemical crosslinking are mainly used to enhance the size-sieving ability of GO membranes for selective ion transport. As for the charge modification method, the strategies of positive/negative-charge modifications are usually employed to tune the long-range electrostatic interaction between GO membranes and the guest ions. This review will deepen the understanding on the mechanism of the ion selectivity of GO membranes, and put forward to the research direction in order to promote the development of GO membrane in the application of ion separation.

    Research progress and tendency of CO2 electrocatalytic reduction to syngas
    Xin LI, Shaojuan ZENG, Kuilin PENG, Lei YUAN, Xiangping ZHANG
    2023, 74(1):  313-329.  doi:10.11949/0438-1157.20221268
    Abstract ( 704 )   HTML ( 38)   PDF (4677KB) ( 466 )  
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    Renewable electric energy drives CO2 electrocatalytic synthesis of chemicals or fuels, which has the advantages of mild reaction conditions, adjustable product selectivity and the use of distributed renewable energy. Syngas, as an important chemical raw gas, can be used to produce methanol, ethanol, olefins and other bulk chemicals, thus CO2 electrocatalytic reduction to syngas is one of important ways to CO2 utilization. However, accurately controlling the CO/H2 ratio with high current density and high selectivity is one of the key scientific problems. In this paper, from the perspective of improving current density and efficiency, and widening the proportion of syngas, we reviewed the latest research progress of CO2 electrocatalytic reduction to syngas, including electrode design, electrolyte development, and electrolyzer structure innovation, and so on. Then, the research progress on the electrocatalytic reduction mechanism of CO2 electrocatalytic reduction to syngas by in-situ characterization and theoretical simulation (DFT, MD) is discussed. Furthermore, it was concluded that the efficiency of CO2 electrocatalytic reduction to syngas can be improved through multi-stage morphology regulation of catalyst, multi-active site design, integration of CO2 capture and conversion system, and the coupling of CO2 reduction and anodic reaction. Finally, the challenges of the industrialization of CO2 electrocatalytic reduction to syngas are discussed and prospected.

    Light-driven microbial hybrid systems improve level of biomanufacturing
    Xin LIU, Jun GE, Chun LI
    2023, 74(1):  330-341.  doi:10.11949/0438-1157.20221321
    Abstract ( 614 )   HTML ( 35)   PDF (2057KB) ( 499 )  
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    As the most abundant and cleanest renewable energy, solar energy has great cost-competitive and development potential. The natural photosynthesis is inherently inefficient and difficult to intervene, while artificial photosynthesis is unstable and costly. It is an urgent need for sustainable development to realize solar-to-chemical conversion in a green and low-carbon way, which is also in line with the demand of green biomanufacturing. Light-driven microbial hybrid system is an emerging technology that integrates the excellent light absorption ability of photosensitizer materials and the specific and efficient synthesis ability of whole-cell microbes, holding great potential in solar-driven fuels and chemicals conversion. This paper reviews the application of light-driven microbial hybrid systems in important reactions such as proton reduction hydrogen production, CO2 reduction conversion, nitrogen fixation, and C—H bond oxidation, and looks forward to the future development trend of light-driven microbial hybrid systems.

    Biosynthesis of vitamin K2 and functional analysis of the biosynthetic enzymes involved in its menadione moiety
    Qiuhua ZHANG, Manlu LIU, Zheng WANG, Yiming ZHANG, Haijia SU
    2023, 74(1):  342-354.  doi:10.11949/0438-1157.20221016
    Abstract ( 673 )   HTML ( 42)   PDF (2012KB) ( 400 )  
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    Vitamin K2 (VK2), a derivative of the 2-methyl-1,4-naphthoquinone (menadione) family, plays an important role in the prevention of osteoporosis and cardiovascular calcification, and its increasing demand has aroused great interest to improve VK2 synthesis and reduce its manufacturing cost for industrial production. We first reviewed the status and some issues confronted in traditional microbial production of VK2. Then we presented its synthesis pathway and engineering efforts performed in recent studies and found that VK2 production could be greatly improved to 1549.6 mg·L-1 in Bacillus subtilis, which was more than 7 times higher than traditional microbial fermentation. Focusing on the synthesis pathway of 2-methyl-1,4-naphthoquinone, which constitutes as the conserved structure of VK2, we summarized the involved enzymes and analyzed their protein structure, catalytic specificity, and mechanism to reveal their roles in synthesis pathway and their internal relationship. Finally, the design, construction and application of VK2 pathway are prospected from the perspective of synthetic biology technology development, which provides a theoretical reference for improving the industrial production of VK2.

    Research progress on new functional nanoparticles prepared by microfluidic technology
    Xintong HUANG, Yuhao GENG, Hengyuan LIU, Zhuo CHEN, Jianhong XU
    2023, 74(1):  355-364.  doi:10.11949/0438-1157.20220935
    Abstract ( 579 )   HTML ( 21)   PDF (4660KB) ( 620 )  
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    Nanoparticles have a wide range of applications in fields such as displays, catalysts and biomedicine, and their controlled preparation has always been the focus of research. Compared with the traditional batch production process, microfluidic technology has the characteristics of high mixing efficiency, rapid mass and heat transfer, accurate reaction condition control, and compatibility with online analysis, which can be used for efficient continuous synthesis of monodisperse nanoparticles and provide a platform for the development of new functional nanoparticles. This paper mainly introduces the application of microfluidic technology in the preparation of new functional nanoparticles in recent years, focusing on the research progress in the preparation of quantum dots, metals and metal oxide nanoparticles, and the future direction is prospected.

    The progress of metal-organic frameworks for non-CO2 greenhouse gases capture
    Muzi LI, Guowei JIA, Yanlong ZHAO, Xin ZHANG, Jianrong LI
    2023, 74(1):  365-379.  doi:10.11949/0438-1157.20221183
    Abstract ( 448 )   HTML ( 34)   PDF (4238KB) ( 293 )  
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    Along with the extensive research of global warming, non-carbon dioxide greenhouse gases have gained increasing attention recently. Because of their large temperature-rising effect and long lifetime, they can generate huge greenhouse effect, so they have become a research hotspot. Especially, efficient capture of non-carbon dioxide greenhouse gases is a new challenge. Adsorptive separation is an energy efficient technology which relies on advanced porous sorbents. Metal organic framework (MOFs) provide new opportunities for the capture of non-carbon dioxide greenhouse gases because of their diverse structures, controllable pore features, and open metal sites. In this review article, the research results of MOF materials for non-carbon dioxide greenhouse gas separation in recent years are summarized, and the separation mechanism of each material is analyzed. The challenges and opportunities of the future research on MOFs for non-carbon dioxide greenhouse gas separation has been discussed.

    Research progress in catalytic hydroconversion of lipid to second-generation biodiesel
    Kuan HUANG, Yongde MA, Zhenping CAI, Yanning CAO, Lilong JIANG
    2023, 74(1):  380-396.  doi:10.11949/0438-1157.20220954
    Abstract ( 799 )   HTML ( 31)   PDF (4964KB) ( 314 )  
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    Biodiesel is a clean and renewable energy source, and it is one of the most potential development directions to deal with problems such as greenhouse effect, environmental pollution, and energy shortage. The second-generation biodiesel is a hydrocarbon mixture prepared by the hydroconversion of lipid with the assistance of hydrogen (H2). It has similar components to the traditional petrochemical diesel. In addition to the advantages of greenness, high cetane number and renewability, it also has the characteristics of good low-temperature fluidity, low oxygen content, high stability and high calorific value. It can be mixed with petrochemical diesel without fraction limitation. This review systematically summarizes the research progress in the preparation of second-generation biodiesel by catalytic hydroconversion of lipid in recent years. We discuss the hydroconversion mechanism, active phase of catalysts, catalyst supports and hydroconversion process, with special emphasis on the design and development of highly efficient hydroconversion catalysts. In addition, the opportunities and challenges in the field of lipid hydrogenation to produce second-generation biodiesel were analyzed, and the future development directions were prospected.

    Modulating luminescent behaviors of Au nanoclusters via supramolecular strategies
    Guojuan QU, Tao JIANG, Tao LIU, Xiang MA
    2023, 74(1):  397-407.  doi:10.11949/0438-1157.20221055
    Abstract ( 345 )   HTML ( 17)   PDF (2990KB) ( 194 )  
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    Au nanoclusters (AuNCs) stand out in the fields of catalysis, bioimaging, sensing, analytical detection, drug delivery, displaying and illumination owing to their abundant optical properties and unique nanostructures. However, the low quantum yield (QY) and single emissive band seriously hinder the development prospects of most AuNCs, and the preparation of AuNCs with tunable luminescence, high QY, and long luminescent lifetime has become current research focus in this field. Supramolecular strategies such as host-guest inclusion, embedding in polymer matrix, hydrogen bonding and electrostatic interactions have been widely used to control the luminescent behavior of AuNCs and improve their QY. In view of this, this review systematically expounds the mechanism of supramolecular strategies to modulate the luminescent behavior of AuNCs, summarizes the recent research progress in the construction and regulation of multifunctional AuNCs based on supramolecular strategies, and looks forward to the opportunities and challenges in the field of AuNC luminescence.

    Thermodynamics
    Prediction of the phase equilibrium of semi-clathrate hydrate in TBAB aqueous solution
    Jin CAI, Xiaohui WANG, Han TANG, Guangjin CHEN, Changyu SUN
    2023, 74(1):  408-415.  doi:10.11949/0438-1157.20221178
    Abstract ( 327 )   HTML ( 22)   PDF (2068KB) ( 101 )  
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    Tetrabutyl ammonium bromide (TBAB) is a widely used hydration promoter that can significantly reduce the formation conditions of hydration reactions. Considering the strongly interactive forces between ions and solvent in TBAB aqueous solution, the electrolyte NRTL equation was adopted for determining the activity coefficient in liquid phase. Coupled with the lattice structure of TBAB hydrate and the Chen-Guo hydrate model, a thermodynamic model for predicting the phase equilibrium conditions of TBAB semi-clathrate hydrate was proposed. The predictions were in good agreement with 221 experimental data points with concentrations of TBAB in the range of 5%—60% (mass). The average relative deviation for equilibrium temperatures is only 0.112%. In addition, the developed model could be further extended for predicting the phase equilibrium conditions of CO2 semi-clathrate hydrate with additives of TBAB and NaCl by correlating the interactive parameters of salts-solvent in mixed electrolytes systems. Using the proposed model, the phase equilibrium conditions of TBAB+NaCl+CO2 semi-clathrate were predicted over TBAB mass fraction ranging from 5% to 20%, and NaCl mass fraction ranging from 3.5% to 10%. The results show that a good agreement was reached between the predictions and experimental data, with the temperature deviations ranging from 0.01 to 1.17 K. This model can provide a theoretical basis for the practical application of hydrate gas separation, gas storage and transportation, and the development of process packages.

    Fluid dynamics and transport phenomena
    Formation and flow characteristics of ordered bubble swarm in a step T-junction microchannel
    Lin SHENG, Yu CHANG, Jian DENG, Guangsheng LUO
    2023, 74(1):  416-427.  doi:10.11949/0438-1157.20221014
    Abstract ( 272 )   HTML ( 19)   PDF (5304KB) ( 137 )  
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    The preparation of microbubbles by microfluidic technology has attracted much attention due to its controllable process and wide operating range. In this work, a step T-junction microchannel was chosen as the device for the microbubble generation to study the bubble swarm self-assembly behavior and its flow characteristics. Effects of the liquid volumetric flow rate, liquid viscosity, gas injection pressure, and channel size on the bubble swarm were investigated. The results show that ordered bubble swarm (bubble swarm crystals) can be formed only when the gas phase content in the channel is greater than the liquid phase content, and the bubble swarm crystals can self-assemble into structures with different numbers of rows along the channel width or depth direction in the confined space. Besides, the effects of different operating parameters on the flow behavior of the bubble swarm crystal were explored. The variation rules of the flow velocity of the bubble swarm crystal with the liquid-phase volumetric flow rate are the same as the rules of the gas-liquid two-phase volumetric flow rate. Finally, the strategies to improve the flow ideality of the system are proposed, and a dimensionless model for the prediction of the flow ideality of the bubble swarm crystal is also developed.

    Study of EDC parameters for predicting entrained flow coal gasification
    Peng QIU, Yang HAN, Jianliang XU, Fuchen WANG, Zhenghua DAI
    2023, 74(1):  428-437.  doi:10.11949/0438-1157.20221131
    Abstract ( 218 )   HTML ( 13)   PDF (2078KB) ( 109 )  
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    The entrained flow coal gasifier is a multi-phase turbulent reactor accompanied by homogeneous reaction processes such as combustion and transformation, which can be simulated by eddy dissipation concept (EDC) model for turbulence-chemical reaction interaction, but the model parameters need to be corrected. The effects of EDC model parameters on syngas temperature and composition were investigated by analyzing the parameter modification range of EDC model for gasifier under Realizable κ-ε condition with a 1500 t/d opposed multi-burner (OMB) coal-water slurry (CWS) gasifier. Four groups of EDC models with different parameters and (finite-rate/eddy-dissipation) ED model was numerically investigated and verified with the outlet industrial data. The results showed that when CD1=0.213,0.272≤CD2≤2.268. After modification of the model constants in this range, the relative errors of temperature, CO and H2 volume fraction at the outlet were lower than original value, and the minimum were -2.54%, -3.93%, and 0.74%, respectively, while those of the ED model were 7.95%, 5.52% and -2.74%, respectively. The temperature and composition results of the EDC simulation with default parameters are always within the range of the boundary parameter model, and the range becomes narrower closer to the gasifier outlet, and the simulation results of each model tend to be consistent.

    Catalysis, kinetics and reactors
    Influence of synergistic effect of acid properties and pore structure of ZSM-5 zeolite on the catalytic cracking performance of pentene
    Yuen BAI, Binrui ZHANG, Dongyang LIU, Liang ZHAO, Jinsen GAO, Chunming XU
    2023, 74(1):  438-448.  doi:10.11949/0438-1157.20221200
    Abstract ( 508 )   HTML ( 32)   PDF (4542KB) ( 459 )  
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    Hierarchical pore HZSM-5 zeolite with different acid properties was prepared by using alkali treatment with different concentrations, and the effect of their pore properties on the catalytic cracking performance of C5 olefins in FCC gasoline was investigated. The structure, morphology, acid properties and pore properties of HZSM-5 zeolite were investigated using XRD, N2 adsorption desorption, ammonia programmed temperature desorption technique (NH3-TPD), pyridine infrared (Py-IR), and scanning electron microscopy (SEM) characterization. The results showed that the appropriate concentration of alkali treatment could increase the amount of strong B acid site and mesopore volume of HZSM-5 zeolite, and significantly increase the conversion of C5 olefins and the yields of ethylene and propylene. When the alkali concentration was 0.2 mol·L-1, the synergistic effect between the strong B acid site and mesopore volume of HZSM-5 zeolite promoted the efficient conversion of C5 olefins, the conversion rate was 84.8% (mass), and the total yield of ethylene-propylene was 86.0% (mass), which was 4.4% and 15.5% higher than that of the untreated HZSM-5 zeolite, respectively.

    Heterogeneous aldol condensation catalyzed with Pickering emulsion
    Yu CHEN, Xiaoyan ZHENG, Hui ZHAO, Erqiang WANG, Jie LI, Chunshan LI
    2023, 74(1):  449-458.  doi:10.11949/0438-1157.20221196
    Abstract ( 290 )   HTML ( 18)   PDF (4111KB) ( 214 )  
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    In recent years, the coal-based synthesis of methyl methacrylate (MMA) process has received extensive attention. However, the aldol condensation reaction of formaldehyde and propionaldehyde has bottleneck problems such as discontinuous reaction process and complicated separation and recovery process. A reinforced water-in-oil (W/O) Pickering emulsion was constructed with surface-modified silica (SiO2) nanospheres used as stabilizers and the emulsifier particles were further “reinforced” by cross-linking to form a dense SiO2 shell layer around the droplets. This Pickering emulsion system not only achieves the “solid loading” of the catalyst and the heterogeneous mild conversion of the aldol condensation reaction process, but also provides opportunities for other homogeneous catalytic reaction systems.

    Separation engineering
    Preparation of a novel separation-sensing membrane and its dynamic monitoring of blood glucose
    Jing ZHANG, Tao LIU, Wei ZHANG, Zhenyu CHU, Wanqin JIN
    2023, 74(1):  459-468.  doi:10.11949/0438-1157.20221096
    Abstract ( 229 )   HTML ( 13)   PDF (4529KB) ( 285 )  
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    Blood glucose is one of the most important physiological indicators. In clinical surgery, blood glucose can sensitively reflect the kidney function of patients to affect the postoperative healing and physiological. However, the existing clinical testing equipment, such as blood glucose meters, biochemical analyzers, etc., can only provide intermittent feedback of test results, and it is difficult to achieve dynamic monitoring of patients’ blood sugar during surgery. As they can only collect intermittent feedback of detection results rely on discrete index points. In view of the above problems, this work proposed the combination of membrane separation technology and biosensing technology to construct a separation-sensing membrane which can synchronously realize dynamic separation of whole blood and online monitoring of blood glucose. Prussian blue (PB) nanoparticles and gold (Au) nanoparticles were grown in situ and synchronously on zirconia ceramic hollow fiber membrane (YSZ) via layer-by-layer self-assembly method. The effect of PB/Au on the hydrophilicity and hydrophobicity of the sensing membrane was investigated, and the plasma separation effect and blood glucose electrochemical detection performance were evaluated under the optimal membrane preparation conditions. The results showed that the best condition was 60 layers which can completely reject all the red blood cells, white blood cells and platelets in the whole blood. The separation-sensing membrane showed a sensitivity of 0.876 μA/(mmol/L), a liner range of 1—15 mmol/L to blood glucose and realized dynamic separation and detection in real human blood samples.

    Energy and environmental engineering
    Temperature swing for CO2 capture driven by radiative cooling and solar heating
    Yingxi DANG, Peng TAN, Xiaoqin LIU, Linbing SUN
    2023, 74(1):  469-478.  doi:10.11949/0438-1157.20221078
    Abstract ( 302 )   HTML ( 19)   PDF (5854KB) ( 477 )  
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    Temperature-swing adsorption is an effective technique for CO2 capture, but the temperature swing procedure is energy-intensive, especially the heating and cooling processes. The low-energy-consumption temperature-swing system is realized by using polypyrrole-based nitrogen-doped porous carbon PPy-650 which combines passive radiative cooling and solar heating. During the adsorption process, the adsorbent layer is coated with a layer of hierarchically porous poly (vinylidene fluoride-co-hexafluoropropene) [P(VdF-HFP)HP], which can cool the adsorbents to a sub-ambient temperature under sunlight through radiative cooling. For desorption, PPy-650 with excellent photothermal conversion ability is exposed to light irradiation for heating. The heating and cooling process is driven entirely by solar energy without any energy input. The regeneration of PPy-650 was investigated by means of adsorption-desorption cycles carried out at 700 W/m2. The results demonstrate that PPy-650 has a good CO2 working capacity (35.69 cm3/g) in this temperature-swing adsorption system, the adsorption capacity of PPy-650 did not decrease.

    Material science and engineering, nanotechnology
    Structural characterization of Z-type perfluoropolyether
    Ruyi TANG, Hanqian PAN, Xiajun ZHENG, Guangxin ZHANG, Xingping WANG, Xili CUI, Huabin XING
    2023, 74(1):  479-486.  doi:10.11949/0438-1157.20221490
    Abstract ( 504 )   HTML ( 25)   PDF (1194KB) ( 358 )  
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    Perfluoropolyether (PFPE) with functional end groups possesses excellent chemical stability and strong processing plasticity, thus being widely applied in high-end fields such as aerospace, electronics, chemical engineering. During production and application, it’s significant to characterize and analyze PFPE structure based on nuclear magnetic resonance technology (NMR). However, due to structure complexity, high molecular weight and wide distribution of PFPE, there have been difficulties in preparing samples for NMR test, distinguishing and attributing the main chain structure and end groups in NMR spectra, which further affects qualitative and quantitative analysis of PFPE. In view of the structural analysis of Z-type PFPE, this study investigated combination of kinds of deuterated solvents and fluorinated cosolvent, sample concentration and test conditions,obtaining a better method of NMR sample preparation. The attribution of main chain structure and end groups of PFPE were determined. Also, the molecular weight, the degree of polymerization, and the composition of two-component PFPE mixture were calculated by analyzing the end groups of PFPE.