This paper presents the numerical investigation of the effects of momentum, thermal and species boundary layers on the characteristics of polycrystalline silicon deposition by comparing the deposition rates in three chemical vapor deposition (CVD) reactors. A two-dimensional model for the gas flow, heat transfer, and mass transfer was coupled to the gas-phase reaction and surface reaction mechanism for the deposition of polycrystalline silicon from trichlorosilane (TCS)-hydrogen system. The model was verified by comparing the simulated growth rate with the experimental and numerical data in the open literature. Computed results in the reactors indicate that the deposition characteristics are closely related to the momentum, thermal and mass boundary layer thickness. To yield higher deposition rate, there should be higher concentration of TCS gas on the substrate, and there should also be thinner boundary layer of HCl gas so that HCl gas could be pushed away from the surface of the substrate immediately.

The numerical simulation of extrudate swell is significant in extrusion processing.Precise prediction of extrudate swell is propitious to the control of melt flow and the quality of final products.A mathematical model of three-dimensional(3D)viscoelastic flow through elliptical ring die for polymer extrusion was investigated.The penalty function formulation of viscoelastic incompressible fluid was introduced to the finite element model to analyze 3D extrusion problem.The discrete elastic viscous split stress(DEVSS)and streamline-upwind PetrovGalerkin(SUPG)technology were used to obtain stable simulation results.Free surface was updated by updating the streamlines which needs less memory space.According to numerical simulation results,the effect of zero-shear viscosity and elongation parameter on extrudate swell was slight,but with the increase of volumetric flow rate and relax time the extrudate swell ratio increased markedly.Finally,the numerical simulation of extrudate swell flow for low-density polyethylene(LDPE)melts was investigated and the results agreed well with others’work.These conclusions provided quantitative basis for the forecasting extrudate swell ratio and the controlling of extrusion productivity shape.

This paper reports a study on the role of fluid flow pattern and dynamic pressure on the permeate flux through a micro filtration membrane in laboratory scale.For this purpose,a dead-end membrane cell equipped with a marine type impeller was used.The impeller was set to rotate in the clockwise and counter clockwise directions with the same angular velocities in order to illustrate the effect of rotation direction on permeate flux.Consequently, permeate fluxes were measured at various impeller rotational speeds.The computational fluid dynamics(CFD)predicted dynamic pressure was related to the fluxes obtained in the experiments.Using the CFD modeling,it is proven that the change in dynamic pressure upon the membrane surface has direct effect on the permeate flux.

During the exploitation of offshore oil and gas,it is easy to form severe slugging which can cause great harm in the riser connecting wellheads and offshore platform preprocessing system.The flow pattern and pressure fluctuation of severe slugging were studied in an experimental simulation system with inner diameter of 0.051 m.It is found that severe slugging can be divided into three severe slugging regimes:regime I at low gas and liquid flow rates with large pressure fluctuation,intermittent flow of liquid and gas in the riser,and apparent cutoff of liquid phase,regime Ⅱ at high gas flow rate with non-periodic fluctuation and discontinuous liquid outflow and no gas cutoff,regime ⅡI at high liquid flow rate with degenerative pressure fluctuation in form of relatively stable bubbly or plug flow.The results indicate that severe slugging still occurs when the declination angle of pipeline is 0,and there are mainly two kinds of regimes:regime I and regime Ⅱ.As the angle increases,the formation ranges of regime I and regime ⅡI increase slightly while that of regime Ⅱ is not affected.With the increase of gas superficial velocity and liquid superficial velocity,the pressure fluctuation at the bottom of riser increases initially and then decreases.The maximum value of pressure fluctuation occurs at the transition boundary of regimes I and Ⅱ.

The separation of Eu³⁺ is studied with a dispersion combined liquid membrane(DCLM),in which polyvinylidene fluoride membrane(PVDF)is used as the liquid membrane support,dispersion solution containing HCl solution as the stripping solution,and 2-ethyl hexyl phosphonic acid-mono-2-ethyl hexyl ester(P507)dissolved in kerosene as the membrane solution.The effects of pH value,initial concentration of Eu³⁺ and different ionic strength in the feed phase,volume ratio of membrane solution to stripping solution,concentration of HCl solution, concentration of carrier,different stripping agents in the dispersion phase on the separation are investigated.The optimum condition for separation of Eu³⁺ is that concentration of HCl solution is 4.0 mol·L^-1,concentration of carrier is 0.16 mol·L^-1,and volume ratio of membrane solution to stripping solution is 30:30 in the dispersion phase, and pH value is 4.2 in the feed phase.The ionic strength has no significant effect on separation of Eu³⁺.Under the optimum condition,when the initial concentration of Eu³⁺ is 0.8×10^-4mol·L^-1,the separation percentage of Eu³⁺ is 95.3% during the separation time of 130 min.The kinetic equation is developed in terms of the law of mass diffusion and the theory of interface chemistry.The diffusion coefficient of Eu³⁺ in the membrane and the thickness of diffusion layer between feed phase and membrane phase are obtained and their values are 1.48×10^-7m²·s^-1 and 36.6μm,respectively.The results obtained are in good agreement with literature data.

Pervaporation has attracted considerable interest owing to its potential application in recovering biobutanol from biomass acetone-butanol-ethanol(ABE)fermentation broth.In this study,butanol was recovered from its aqueous solution using a polydimethylsiloxane(PDMS)/ceramic composite pervaporation membrane.The effects of operating temperature,feed concentration,feed flow rate and operating time on the membrane pervaporation performance were investigated.It was found that with the increase of temperature or butanol concentration in the feed, the total flux through the membrane increased while the separation factor decreased slightly.As the feed flow rate increased,the total flux increased gradually while the separation factor changed little.At 40℃ and 1%(by mass) butanol in the feed,the total flux and separation factor of the membrane reached 457.4 g·m²·h^-1 and 26.1,respectively.The membrane with high flux is suitable for recovering butanol from ABE fermentation broth.

Membrane fouling is one of the major obstacles for reaching a high flux over a prolonged period of ultrafiltration(UF)process.In this study,a sulfonated-polyethersulfone(SPES)/nano-TiO₂ composite UF membrane with good anti-fouling performance was fabricated by phase inversion and self-assembly methods.The TiO₂ nanoparticle self-assembly on the SPES membrane surface was confirmed by X-ray photoelectron spectroscopy (XPS)and FT-IR spectrometer.The morphology and hydrophilicity were characterized by scanning electron microscopy(SEM),atomic force microscopy(AFM)and contact angle goniometer,respectively.The anti-fouling mechanism of composite UF membrane was discussed through the analysis of the micro-structure and component of UF membrane surface.The results showed that the TiO₂ content and the micro-structure of the composite UF membrane surface had great influence on the separation and anti-fouling performance.

The study concerns the use of MgCl₂-supported high-activity Ziegler-Natta catalysts for the polymerization of ethylene.In particular,two types of catalysts were investigated,which were N-catalyst(BRICI)and improved polyethylene catalyst.The effects of catalyst structure on kinetic behavior were examined.The distribution of active centers in these catalysts was investigated by energy dispersive analysis by X-rays(EDAX),and morphologies of catalyst particles and polymer products were examined by scanning electron microscope(SEM).Hydrogen response and copolymerization performance were investigated and compared with the two catalysts.The results were correlated with the kinetic behavior of the two catalysts and appropriate models for polymer particle growth were presented.The improved polyethylene catalyst showed higher activity,better hydrogen response and copolymerization performance.

The epoxidation of unsaturated fatty acid methyl esters(FAMEs)by peroxyacetic acid generated in situ from hydrogen peroxide and acetic acid was studied in the presence of SO₃H-functional Brnsted acidic ionic liquid (IL)[C₃SO₃HMIM][HSO₄] as catalyst.The effects of hydrogen peroxide/ethylenic unsaturation ratio,acetic acid concentration,IL concentration,recycling of the IL catalyst,and temperature on the conversion to oxirane were studied.The kinetics and thermodynamics of unsaturated FAMEs epoxidation and the kinetics of oxirane cleavage of the epoxidized FAMEs by acetic acid were also studied.The conversion of ethylenic unsaturation group to oxirane, the reaction rate of the conversion to oxirane,and the rate of hydrolysis(oxirane cleavage)were higher by using the IL catalyst.

The alkylation of p-cresol with tert-butanol(TBA)to 2-tert-butyl-p-cresol(TBC)catalyzed by a novel multiple-SO₃H functioned ionic liquid(IL1)was investigated.Meanwhile,the catalytic activity of this novel ionic liquid was compared with other four traditional ionic liquids.The results showed that IL1 has superior catalytic activity to other four traditional ionic liquids with the conversion of 85.3%and selectivity of 95.2%.Also,the reaction conditions were investigated to obtain the optimum conditions.Operational simplicity,small amount of usage,high activity,reusability and selectivity are the key features of this methodology.

The lanthanum aluminum mesoporous materials were synthesized using sodium dodecyl sulfate as a template agent by ultrasonic hydrothermal method.The resulting samples were characterized by low angle X-ray diffraction(XRD),N₂ adsorption-desorption studies,transmission electron microscopy(TEM)and surface morphology analysis(SEM),surface acid(NH₃-TPD),reducibility properties(TPR),X-ray energy dispersive spectrometer(EDS)and thermogravimetric analysis(TG/DTG).A l/La composite mesoporous material were synthesized with n(Al):n(La)=70:1.0,80℃ of reaction temperature,20 h of reaction time,12 h of crystallization time,650℃ of calcination temperature.The specific surface area of the sample is 273.90 m²·g^-1,with the average diameter 5.642 nm and pore volume 0.2354 cm³·g^-1.The samples have mesoporous structure and its particles are similar to a worm-shaped tubular structure.The influence of calcination temperature on the surface physical and chemical properties of Al/La composited mesoporous materials was examined,and the results showed that the acid strength was increased but the amount of acidic sites is decreased as the calcination temperature increased.It was found that the sample calcined at 650℃ had appropriate acid content,acid strength and better reducibility.

A three phase fluidized bed reactor was used to investigate the combined effect of adsorption and oxidation for phenolic wastewater treatment.Aqueous solutions containing 10 mg·L^-1 of phenol and ozone were continuously fed co-currently as upward flow into the reactor at constant flow rate of 2 and 1 L·min^-1,respectively.The phenolic treatment results in seven cases were compared:(a)O₃ only,(b)fresh granular activated carbon(GAC),(c) 1st reused GAC,(d)2nd reused GAC,(e)fresh GAC enhanced with O₃,(f)1st reused GAC enhanced with O₃,and (g)2nd reused GAC enhanced with O₃.The phenolic wastewater was re-circulated through the reactor and its concentration was measured with respect to time.The experimental results revealed that the phenolic degradation using GAC enhanced with O₃ provided the best result.The effect of adsorption by activated carbon was stronger than the effect of oxidation by ozone.Fresh GAC could adsorb phenol better than reused GAC.All cases of adsorption on GAC followed the Langmuir isotherm and displayed pseudo second order adsorption kinetics.Finally,a differential equation for the fluidized bed reactor model was used to describe the phenol concentration with respect to time for GAC enhanced with O₃.The calculated results agree reasonably well with the experimental results.

This job focuses on the stroke regulation of a class of high-precision metering pumps.A parametertuning method of robust non-fragile PID(proportional-integral-derivative)controllers is proposed with the assumption that a PID controller has additive gain perturbations.An H-infinite robust PID controller can be obtained by solving a linear matrix inequality.This approach can guarantee that the closed-loop control systems is asymptotically stable and the H-infinite norm of the transfer function from the disturbance to the output of a controlled system is less than a given constant to attenuate disturbances.The simulation case shows that the control performance of the proposed strategy is significantly better than the traditional PID approach in the situation with perturbations of controller parameters.

Dynamic model for dehydration process of industrial purified terephthalic acid solvent is investigated to understand and characterize the process.A temperature differential expression is presented,which ensures the equation to convergence and short computation time.The model is used to study the dynamic behavior of an azeotropic distillation column separating acetic acid and water using n-butyl acetate as the entrainer.Responses of the column to feed flow and aqueous reflux flow are simulated.The movement of temperature front is also simulated.The comparison between simulation and industrial values shows that the model and algorithm are effective.On the basis of simulation and analysis,control strategy,online optimization and so on can be implemented effectively in dehydration process of purified terephthalic acid solvent.

The CaCl₂ solubility in 2-methyl-butanol acetate and the vapor pressure of 2-methyl-butanol acetate containing CaCl₂ were measured in the range of 90-135℃ and from very low salt concentration to saturation.The experimental data were correlated with two equations,a modified Antoine equation with the dissolved salt taken into account and a nonrandom two liquid-electrolyte(e-NRTL)model.Both models are in good agreement with the experimental data.This study provides essential physical data for further investigation of vapor-liquid equilibrium system containing salt.

The solubilities of the quinary system Na⁺,K⁺,Mg²⁺//Cl,NO₃^--H₂O and its two quaternary subsystems, Na⁺,K⁺,Mg²⁺//NO₃^--H₂O and K⁺,Mg²⁺//Cl,NO₃^--H₂O,were studied by isothermal method at 25℃ and their phase diagrams were plotted.In the equilibrium phase diagram of quaternary system Na⁺,K⁺,Mg²⁺//NO₃^--H₂O, there are one invariant point,three univariant curves and three regions of crystallization with one salt:NaNO₃, KNO₃ and Mg(NO₃)2·6H₂O.In the equilibrium phase diagram of quaternary system K⁺,Mg²⁺//Cl,NO₃^--H₂O,there are three invariant points,seven univariant curves and five regions of crystallization with one salt:KNO₃,KCl, Mg(NO₃)2·6H₂O,MgCl₂·6H₂O and KCl·MgCl₂·6H₂O.In the equilibrium phase diagram of the quinary system Na⁺, K⁺,Mg²⁺//Cl,NO₃^--H₂O,there are four invariant points,and seven regions of crystallization with one salt:NaCl, KCl,NaNO₃,KCl·MgCl₂·6H₂O,KNO₃,MgCl₂·6H₂O and Mg(NO₃)2·6H₂O.

Mixotrophic growth is one potential mode for mass culture of microalgae and cyanobacteria particularly suitable for the production of high value bioactive compounds and fine chemicals.The typical heterocystous cyanobacterium Anabaena sp.PCC 7120 was grown in the presence of exogenous glucose in light.Glucose improved the cell growth evidently,the maximal specific growth rate under mixotrophic condition(0.38 d^-1)being 1.6-fold of that of photoautotrophic growth.Mixotrophy caused a variation in cellular pigment composition,increasing the content of chlorophyll a and decreasing the contents of carotenoid and phycobiliprotein relative to chlorophyll a.Fluorescence emission from photosystem Ⅱ(PSⅡ)relative to photosystem I was enhanced in mixotrophic cells,implying an increased energy distribution in PSⅡ.Glucokinase(EC 2.7.1.2)activity was further induced in the presence of glucose.The mixotrophic culture was scaled up in a 15 L airlift photobioreactor equipped with an inner and an outer light source.A modified Monod model incorporating the specific growth rate and the average light intensity in the reactor was developed to describe cell growth appropriately.The understanding of mixotrophic growth and relevant physiological features of Anabaena sp.PCC 7120 would be meaningful for cultivation and exploitation of this important cyanobacterial strain.

Physicochemical properties of bio-oil obtained from fast pyrolysis of rice husk were studied in the present work.Molecular distillation was used to separate the crude bio-oil into three fractions viz.light fraction,middle fraction and heavy fraction.Their chemical composition was analyzed by gas chromatograph and mass spectrometer(GC-MS).The thermal behavior,including evaporation and decomposition,was investigated using thermogravimetric analyzer coupled with Fourier transform infrared spectrometer(TG-FTIR).The product distribution was significantly affected by contents of cellulose,hemicellulose and lignin.The bio-oil yield was 46.36%(by mass) and the yield of gaseous products was 27%(by mass).The chemicals in the bio-oil included acids,aldehydes,ketones,alcohols,phenols,sugars,etc.The light fraction was mainly composed of acids and compounds with lower boiling point temperature,the middle and heavy fractions were consisted of phenols and levoglucosan.The thermal stability of the bio-oil was determined by the interactions and intersolubility of compounds.It was found that the thermal stability of bio-oil was better than the light fraction,but worse than the middle and heavy fractions.

Recombinant Escherichia coli pUDP,which overexpressed uridine phosphorylase(UPase),was constructed.0.5 mmol·L^-1 lactose had a similar induction effect as the commonly used inducer IPTG during 2.5-5.5 h of cell growth.The lactose-induced UPase was stable at 50℃.Wet cells of pUDP was used as catalyst to biosynthesize 5-fluorouridine from³0 mmol·L^-1 uridine and 5-fluorouracil in phosphate buffer(pH 7.0)catalyzed at 50℃ for 1.5 h and the yield of 5-fluorouridine was higher than 68%.Under the optimum reaction conditions for production of 5-fluorouridine,5-methyluridine and azauridine were synthesized from uridine by pUDP,the yield was 61.7% and 47.2% respectively.Deoxynucleosides were also synthesized by pUDP,but the yield was only about 20%.

The seed germination and tomato seedling tests showed that Bacillus subtilis SL-13 could promote the sprouting and seedling growth of tomato.The fresh and dry weight of tomato seedlings increased 42.86%and 18.75%,respectively.The control efficacies of the SL-13 to tomato Rhizoctonia rot were 20.65% and 35.23% in the greenhouse and field,respectively.The growth of the plant-pathogenic fungus Rhizoctonia solani was considerably inhibited in the presence of the strain SL-13 culture supernatant.The main antifungal protein was detected to be chitinase through vitro assay.The chitinase was purified with DEAE-Sepharose fast flow ion exchange column chromatography and Sephadex G-75 gel filtration for further characterization.The optimal pH and temperature for the chitinase activity were 7.0 and 50℃,respectively.It was demonstrated that the enzyme was stable at pH 5-9 and 40-60℃.70% of the enzyme activity was retained when incubated at 121℃ and 0.11 MPa for 20 min,and the enzyme was not sensitive to protease K and ultraviolet radiation.Thus it is suitable for effective biological control in relatively unstable environment.

Vitamin E succinate was synthesized in organic solvents using a modified Novozym-435 as catalyst.In order to improve the catalytic performance of Novozym-435,the enzyme was modified using acetic anhydride, propionic anhydride and succinic anhydride separately.We found that both the hydrolytic activity and the thermal stability of the modified Novozym-435 were enhanced compared with the unmodified enzyme.The modified Novozym-435 catalysts were used to synthesize the succinate derivative of vitamin E.Compared with the native Novozym-435,the catalytic activity of the modified novozym-435 in promoting the synthesis of vitamin E succinate was dramatically increased,with the novozym-435 modified with succinic anhydride(N435-S)as the most active catalyst.Conditions for the synthesis of vitamin E succinate were also optimized.A mixture of tert-butanol and DMSO(volume ratio of 2:3)was the most suitable medium for the reaction,whereas the appropriate molar ratio of vitamin E to succinic anhydride and reaction temperature were 1:5 and 40℃,respectively.Under these reaction conditions,the yield of vitamin E succinate reached 94.4%.N435-S could be reused for five batches.

A new type of reactor,featured with impinging stream-rotating packed bed(IS-RPB)and coil pipes,was designed and used to prepare p-hydroxybenzaldehyde(PHB)by hydrolysis from diazonium salts.The influence of operating parameters,such as reaction temperature,reaction time and high gravity factor,on the yield of PHB was investigated.Compared with the traditional kettle-type reactor,the yield of PHB with the new reactor is increased significantly and the reaction time is much shorter.Under the optimum conditions,the yield of PHB is increased from 51% to 84.1%.The reactor offers an opportunity for replacing the traditional batch mode operation with a continuous process.

Monotungsten carbide and titania nanocomposite with core-shell(WC@TiO₂)structure was prepared by a new approach of spray drying and reduction-carbonization reaction,with titania nanopowder and ammonium metatungstate as precursors,methane as carbon source,and hydrogen as reduction gas.The sample was characterized by X-ray diffraction,scanning electron microscope,high resolution transmission electron microscope and X-ray energy dispersion spectroscopy.The results show that its crystal phase is composed of brookite,tungsten and monotungsten carbide.The morphology of the sample particle is irregular sphere-like,with a diameter smaller than 100 nm.Its chemical components are titanium,tungsten,carbon and oxygen.Monotungsten carbide nanoparticles lie on the surface of titania core and form an incomplete shell around titania core in the nanocomposite.The measurement with a microelectrode system of three electrodes shows that the sample is electrocatalytic active to nitrophenol in basic solution at room temperature.Its peak potential is at 0.988 V(vs saturated calomel electrode (SCE)),which is more negative than the peak potential,0.817 V(vs SCE),of mesoporous monotungsten carbide, and its peak current is 8.809μA,which is higher than the peak current,4.058μA,of mesoporous monotungsten carbide.The hydrogen generation potential of the sample is at1.199 V(vs SCE),which is more negative than that of pure nanosized monotungsten carbide at 1.100 V(vs SCE).These results show that the presence of titania in the sample can lower the peak potential of nitrophenol electrocatalysis and its hydrogen generation potential,and increase its peak current of nitrophenol electrocatalysis in basic solution at room temperature.This indicates a synergistic effect of titania and monotungsten carbide in electrocatalysis.

It is of great significance to study gas hydrate because of following reasons. (1) Most organic carbon in the earth reserves in the form of natural gas hydrate, which is considered as a potential energy resource for the survival of human being in the future. (2) A series of novel technologies are based on gas hydrate. (3) Gas hydrate may lead to many hazards including plugging of oil/gas pipelines, accelerating global warming up, etc. In this paper, the latest progresses in exploration and exploitation of natural gas hydrate, the development of hydrate-based technologies including gas separation, gas storage, CO₂ sequestration via forming hydrate, as well as the prevention of hydrate hazards are reviewed. Additionally, the progresses in the fundamental study of gas hydrate, including the thermodynamics and kinetics are also reviewed. A prospect to the future of gas hydrate research and application is given.

The kinetics of simultaneous transesterification and esterification with a carbon-based solid acid catalyst was studied.Two solid acid catalysts were prepared by the sulfonation of carbonized vegetable oil asphalt and petroleum asphalt.These catalysts were characterized on the basis of elemental analysis,acidity site concentration,the Brunauer-Emmett-Teller(BET)surface area and pore size.The kinetic parameters with the two catalysts were determined,and the reaction system can be described as a pseudo homogeneous catalyzed reaction.All the forward and reverse reactions follow second order kinetics.The calculated concentration values from the kinetic equations are in good agreement with experimental values.

Three stable 4-substituted pyridine-based ruthenium(Ⅱ)complexes[RuCl₂(PPh₃)L](L=4-R-2,6-bis (diethylaminomethylene)pyridine,R=Br,H or allyloxy)were synthesized.The catalytic activities of the complexes toward transfer hydrogenation from alcohols to ketones were investigated.The electronic effects of the para-substituent in the pyridyl ring were probed and we found that the electron-donating group increased the catalytic activity.The result suggests that an electron-donating group is probably preferential for linking the catalytic ruthenium complex and the chemically inert supporting molecules such as a carbosilane dendrimer.

A direct contact membrane distillation(DCMD)process was applied to prepare high concentration polyaluminum chloride(PACl)with high Al_c content.The changes in total Al concentration(Al_T)and Al species distribution were investigated.The results showed that Al_T increased but the flux decreased with operating time during the DCMD process.The Al_c content increased from 65%to 81% while the Al_b content decreased from 34% to 18%,and the Al_a content was almost 1%in the process.2.1 mol·L^-1 PACl with 81%Al_c was successfully prepared by DCMD method.Thus the DCMD is an effective method for preparing high concentration PACl with high Al_c content.