The drug polymorphism has a profound effect on the quality, safety and efficiency of the drug product.The Twelfth Five-Year Development Plan of China's Pharmaceutical Industry puts forward one of the major development tasks and technologies focused on the improvement in drug polymorphism study to enhance the quality and safety of the drugs.In this paper, the solubility behavior coupled with the solid state and solution mediated transformation of drug polymorphs are introduced and analyzed.In addition, solvent and additive/template play a critical role in the manipulation of drug crystal form.In many cases, physical field (ultrasound, microwave and high gravity-field)-assisted crystallization gives different results for the manipulation of drug crystal form by specific mechanism.Meanwhile, with the rapid development of process analytical technologies, process optimization and control are enhanced through getting more knowledge of drug polymorphism transformation.In the future, the research of transformation and manipulation of pharmaceutical drug polymorphism will focus on the molecular assembly and regulation, process analysis and structure-activity relationship of drugs.

Hierarchical porous zeolites synthesis procedures with soft templates and their catalytic performance are described in detail.The soft templates used for this purpose mainly include two types.One type is the gemini-type, polyquaternary ammonium surfactant, and the other type is the amphiphilic organosilane surfactant.The synthesis techniques with the two types of surfactants and the structural properties of the synthesized zeolites are reviewed.The catalytic performance of synthesized zeolites is discussed.The research on catalytic behavior focuses on three aspects:the activity and selectivity of synthesis of organic macromolecular compounds, the properties of catalytic pyrolysis of biomass, and the slow deposition of coke against deactivation in the synthesis of organic macromolecular compounds.

The proven efficiency of enzyme catalysis, in terms of high stereo- and regio-selectivity, mildness and environmental friendliness, makes the enzymatic synthesis of polyester a promising route for functional polyester-based materials.This review begins by a survey of recent progress in the enzymatic synthesis of polyesters with emphasis on enzyme catalysts and catalytic process.Then the fundamentals for enzymatic synthesis are discussed with highlight on development of catalysts and intensification of synthesis process from the viewpoint of chemical engineering.The prospects for enzymatic synthesis polyesters are presented.

The product from free radical and coordination polymerization generally are homopolymer or random copolymer with broad molecular weight distribution.In the past two decades, the breakthroughs in controlled/living radical and coordination polymerization and shuttling polymerization make it possible to use almost all vinyl monomers, particularly those cheap monomers, to produce more complex chain structures like di-, tri-block copolymer and gradient copolymers.With rational design, these copolymers might be high performance and high added value synthetic materials.The mechanisms and the up-to-date progress of these polymerization methods were introduced, and their possible applications were discussed.

Vanadium redox flow battery(VRB),which is regarded as one of the most promising devices for massive electricity storage in renewable energy and energy-saving processes,has attracted much attention,because of its long life-time,simple configuration and independent power and capacity ratings.Proton conductive membrane,one of key materials in VRB,performs the role of conducting protons during charge/discharge recycle,and prevents vanadium ions from direct contact between the positive and negative electrolytes.To achieve high energy efficiency,long life and low cost of VRB stack,the membrane should meet the requirements of high conductivity,chemical and mechanical resistance,low permeability of vanadium ions and acceptable cost.So far,Nafion membranes are generally employed in VRB due to their both high conductivity and chemical stability,however,their extremely high cost and poor ion selectivity have become the main barrier of commercialization of VRB.In this review,a detailed introduction about recent progress in the field of proton conductive membranes for VRB is given,including three aspects:(i)post-treated Nafion membranes to improve selectivity;(ii)non-perfluorinated membranes from polymerization and sulfonation of monomers; and(iii)nano-porous membranes based on difference between ion stokes radius and its valence,which provides selectivity for protons towards vanadium ions.Finally,there is a highlight of the relationship between morphology and performance of the advanced proton conductive membranes for research and development in future.

The use of CO₂ for substituting volatile organic compounds in polymer processing, i.e., supercritical CO₂-assisted polymer processing, has attracted increasing attention in recent years. Dissolution of CO₂ in polymer could swell, plasticize and deliver small molecules into the polymer matrixes. Consequently, the structure and morphology of the polymer would change, as well as the fundamental properties, including polymer crystallization, interfacial tension between polymer and gas, and rheology of CO₂/polymers melt.CO₂-induced changes in these properties could be used to realize the supercritical CO₂-assisted polymer processing, e.g., CO₂-assisted polymer grafting, CO₂-assisted penetrating of small molecules into polymer and CO₂-assisted polymer foaming.Several cases from the authors' laboratory are presented for elucidating how to use the changes to manipulate the CO₂-assisted polymer processing.The cases include CO₂-induced crystallization of isotactic polypropylene and syndiotactic polypropylene, CO₂-induced crystal phase transition of isotactic poly-1-butene, and how to use CO₂-induced crystallization to manipulate melt strength of three linear polymers, i.e., isotactic polypropylene, poly(lactic acid)and poly(ethylene terephthalate), to prepare the polymer foams with different structures.

Pure monoclinic MgBO₂(OH) nanowhiskers were synthesized by room temperature co-precipitation followed by hydrothermal treatment at 220—240℃ for 6.0—30.0 h, using MgCl₂·6H₂O, H₃BO₃, and NaOH as raw materials with molar ratio of Mg:B:Na=2:3:4.Enlightened by mechanical mixture model and group contribution method, a novel subunit contribution model for the assessment of thermodynamic properties such as Δ_fH_m and Δ_fG_m of borates was developed, by introducing correction factor k and reasonably decomposing the complex double salt metal borates into constitutional subunits according to mass conservation.The as-developed model was utilized to assess Δ_fH_m and Δ_fG_m at various temperatures for precipitate Mg₇B₄O₁₃·7H₂O and hydrothermal product MgBO₂(OH), based on which the values of Δ_rH_m and Δ_rG_m of the co-precipitation of Mg₇B₄O₁₃·7H₂O and hydrothermal conversion to MgBO₂(OH) were obtained.The results show that, the room temperature co-precipitation can occur spontaneously whereas the hydrothermal conversion can only be performed spontaneously at high temperature. The feasibility for the co-precipitation as well as the hydrothermal conversion turns to be higher with the increase in the temperature and time.The subunit contribution model is beneficial for the analysis and prediction of controllable synthesis of other complex double salt nanostructures via the soft-chemistry based method.

The COSMO-SAC model is an effective method for calculation of infinite dilution activity coefficients (IDACs), and IDACs of organic solutes or ionic liquids (ILs) can be calculated if the structures of the molecules are known.The most time consuming step in COSMO-SAC model is the generation of σ-profile via quantum mechanics.A σ-profile database including 32 anions and 191 cations were established by DMol3 in Materials Studio.A computer aided molecular design method based on COSMO-SAC and the σ-profile database was proposed to select ionic liquid solvents for the liquid-liquid extraction process.The mixture of ethanol-ethyl acetate was used to test the ionic liquid solvent selection method.Effective ionic liquid solvents were selected via such a method and some of them were verified by liquid-liquid equilibrium data of ternary system of ethanol-ethyl acetate-ionic liquid in literature, which indicated that the selection method of ionic liquid solvents was effective.

The fluid dynamics of the gas-liquid-liquid three-phase micro-dispersion process was studied in a double T-junction microchannel device.Two main flow patterns named "gas-in-oil-in-water coupled emulsion flow" and "bubble contained oil-water parallel flow" were observed and the effects of fluid feeding sequence, superficial velocity and confined microchannel on those flow patterns were discussed.A flow pattern map was established based on the experimental result to describe the flow pattern evolution.Mono-dispersed micro-bubbles with average volume ranging from 22 nl to 54 nl were controllably prepared together with the gas-in-oil coupled dispersed phase, whose average volume changed from 60 nl to 81 nl.Based on the Rayleigh-Plateau break-up mechanism of gas phase, mathematical equations were established to calculate the dispersed volumes of bubbles and coupled emulsions.

The flow behavior of polymer solutions with relatively high viscosity in a coaxial micro-channel device was investigated.In the experiment, two kinds of flow patterns, dripping and jetting, could be formed.The jetting regime occurred as flow rate and viscosity of the fluids increased.The influence of two-phase viscosities and flow rates on drop size was investigated.The results could be used to guide the preparation of polymer micro-sized spheres.Mathematic models for predicting drop size in two flow patterns were established separately, and the calculated values fitted experimental results well.

Based on the traditional polysilicon reduction furnace, a novel polysilicon reduction furnace is presented.The velocity and temperature fields are simulated by using computational fluid dynamic.The simulation result of the flow field shows that the flow pattern of the gas mixture in the novel furnace is plug flow, which is fundamentally different from that in traditional furnace.The simulation shows that the temperature field in the novel furnace can be controlled by changing the operating parameters, which solves the problem of high local temperature in traditional furnace, avoids the generation of the silicon powder and reduces the radiation power consumption.The energy consumption in the novel furnace is 8.5% lower than that in the traditional furnace.

Obvious electrostatic effects are commonly found in industrial fluidized bed, which influences the hydrodynamics of fluidized bed and causes security risks constantly.However, the application of external electric field can 'turn harm into benefit'.In order to investigate the hydrodynamics of gas-solids fluidized bed with applied electric field, CFD simulation coupled with the electrostatic model was carried out.Through a decoupling method, the axial electrostatic potentials profiles and particle movements in the fluidized bed were investigated.The simulations presented a Z-shaped axial profile of potential in traditional fluidized bed, which was in good agreement with the experimental data.With the application of direct current (DC) electric field, the simulations showed that the region of positive potential expanded obviously, whilst the region of negative potential was also spread.Under DC electric field, the assembling of small particles was weakened near the wall, but aggregation of small particles appeared near the central electrode.By using AC electric field, the concentration of small particles near the wall was slightly lower than that in the normal fluidized bed.According to the mean electric field distribution produced by charged particles in AC field, it was observed that the electrostatic field had different directions.In the region near the distribution plate, the electrostatic field directed towards the center, while in the region near the bed level, the direction of electrostatic field headed towards the wall.

Agitators were introduced to gas-solids fluidized beds to improve fluidization performance and scrape sticky particles from internal bed wall.Numerical simulations based on the computational fluid dynamics (CFD) method were carried out to predict bubble behavior in the agitated fluidized bed.The Euler-Euler two-fluid model and the kinetic theory of granular flow were incorporated to describe the gas-solids flow, whist the multiple reference frame method was applied to deal with the rotation of agitator.The numerical models were validated by bed pressure drop and its fluctuation obtained in the experiment.The bubble behavior and fluidization performance were investigated in terms of pressure fluctuation.The results indicated that the amplitudes of pressure fluctuation and its power spectrum were reduced by increasing agitation speed of frame impeller, while dominating frequency had positive but inconspicuous correlation with agitation.The characteristics of pressure fluctuation showed that bubble size in the fluidized bed went down with a rise in agitation speed, which might lead to the transition from bubbling fluidization to particulate fluidization.

Hydrodynamics in gas-liquid-solids circulating fluidized beds with low solids holdups of resin particles was experimentally investigated with a high-speed image measurement and treatment technique of complementary metal oxide semiconductor.Influences of superficial liquid velocity, particle diameter and density, liquid surface tension and viscosity on the phase holdups, average gas bubble diameter, circulating rate of solids particles both in the riser and in the downer and bubble motions were investigated. Experimental data with reasonable physical explanations of the hydrodynamics of gas-liquid-solids circulating fluidized beds were obtained.

A high-speed camera was used to visualize and determine the size of formed droplet for liquid-liquid two-phase flow in the T-junction microchannels with different aspect ratios.Microchannels with different dimensions of 400 μm×400 μm, 400 μm×600 μm, 400 μm×800 μm in depth and width were used in this work.Cyclohexane and deionized water with 0.3% surfactant sodium dodecyl sulfate (SDS)-glycerol (20%,40%,60%) were used as the oil (dispersed) and water (continuous) phases, respectively.The effects of microchannel geometry, flow rates of both phases and physical properties of fluids on the size of droplet formed were investigated in the slug, transient and droplet regimes.The result showed that the droplet size decreased with increasing flow rate, viscosity and capillary number of the continuous phase, while it increased with increasing width of microchannels and flow rate of the dispersed phase.The correlations for predicting the size of formed droplet were proposed in taking capillary number, ratio of oil/water flow rates and aspect ratio of microchannels into account, and the calculated values by presented correlations agreed well with the experimental data.

Pt/Al₂O₃ catalysts with Pt particle sizes of 2.0, 4.6 and 12.1 nm were prepared by the ethylene reduction method and used to study the effect of Pt particle size on coking rate and nature of coke formed.Meanwhile, a PtSn/Al₂O₃ catalyst was also prepared by the impregnation method in order to elucidate the effect of Sn addition on coking properties of Pt catalyst.The catalysts were characterized by H₂ chemisorption, TEM, thermogravimetric analysis, elemental analysis, infrared spectroscopy and Raman spectroscopy, respectively.The experimental results showed that coking rate on Pt metal decreased with increasing size of Pt particle.The coke formed on smaller Pt particles was of higher degree of graphitization and lower content of hydrogen.Moreover, for PtSn/Al₂O₃ catalyst, its coking rate on Pt metal was higher than that of Pt/Al₂O₃ catalyst, and the coke formed was also of higher graphitization. Using coke formation mechanism obtained, a conceptual design of catalyst with high performance for propane dehydrogenation was then tentatively proposed.

A CaO-Ca₉Al₆O₁₈ sorbent with a mass fraction of CaO of 80% was prepared by the wet mixing method.Calcium citrate and aluminum nitrate were used as calcium and aluminum precursors, respectively. The CO₂ capture performance of the sorbent was investigated by using thermogravimetry.The results showed that the CaO-Ca₉Al₆O₁₈ sorbent exhibited excellent CO₂ capture capacity and long-term cyclic stability, and its conversion remained above 77% after 50 consecutive cyclic operations, which was much better than that of conventional CaO sorbent.The carbonation kinetics between CO₂ and the CaO-Ca₉Al₆O₁₈ sorbent was then studied over a temperature range of 500—700℃ and CO₂ partial pressure of 0.005—0.015 MPa.The fast reaction regime (controlled by chemical reaction) and the slow reaction regime (controlled by diffusion) of the carbonation reaction were successfully described by an ion reaction model and an apparent model, respectively, and the corresponding activation energies were 25.6 kJ·mol^-1 and 57.7 kJ·mol^-1, respectively.The predicted conversions of the CaO-Ca₉Al₆O₁₈ sorbent agreed well with the experimental data.Finally, the kinetic model established was successfully used to predict the carbonation reaction of long-term cyclic operation.

In spite of great importance of Phillips CrO_x/SiO₂ catalyst for commercial polyethylene production and long term research efforts, polymerization mechanism, especially initiation mechanism, still remains unclear.The effect of surface fluorination of silica support on initiation of ethylene polymerization during induction period over Phillips catalyst adsorbed with different amounts of formaldehyde molecules was investigated with the density functional theory.It was demonstrated that no reaction could be initiated over cluster models adsorbed with two formaldehyde molecules on account of steric hindrance.For cluster models adsorbed with one formaldehyde molecule, ethylene dimerization to 1-butene and metathesis to propylene took place via chromacyclopentane intermediate, and fluorination of silica support showed minor influence on both reactions.After a complete desorption of formaldehyde molecules, further ring expansion to chromacycloheptane occurred and surface fluorination of silica support showed improvement on this process.Fluorination of silica support was unfavorable to ring-opening of chromacycloheptane to give 1-hexene.It was also demonstrated that fluorination showed positive effect on chain propagation over models of Cr^Ⅲ-alkyl active sites during ethylene polymerization.

The selective oxidation of alkanes as a green process remains a challenging task because of inactive C—H oxidation.Heterogeneous Ru-polyoxometalates catalysts were synthesized by using organo-ruthenium supported heteropolytungstates, [Sb₂W₂₀O₇₀(RuC₆H₆)₂]^10-, [Bi₂W₂₀O₇₀(RuC₆H₆)₂]^10-, [Sb₂W₂₀O₇₀(RuC₁₀H₁₄)₂]^10-, and [Bi₂W₂₀O₇₀ (RuC₁₀H₁₄)₂]^10- anchored on 3-aminopropyltriethoxysilane (apts)-modified mesoporous SBA-15.The catalysts were characterized by X-ray diffraction (XRD), N₂-adsorption measurements and Fourier transform infrared reflectance (FT-IR) spectroscopy.The results of these analyses indicated that these catalysts had high surface area, uniform hexagonal channels which were similar to those of SBA-15, and organo-ruthenium supported heteropolytungstates were highly dispersed in the pores of the modified silica.The heterogeneous Ru-polyoxometalates catalysts were used as catalysts for the solvent-free aerobic oxidation of n-hexadecane to alcohols and ketones by using air as the oxidant under ambient conditions.They exhibited exceptionally high catalytic performance through a classical free-radical autoxidation mechanism.Therefore, the catalysts demonstrated the prospect of this type of heterogeneous catalyst for practical applications.

The analysis on the crystallization of cefodizime sodium solvate shows that the conversion-time curve presents three characteristics:S-shape, the turning-point, and the turning-point corresponding to the maximum crystallization rate.Therefore, the crystallization of cefodizime sodium solvate could be assumed as an autocatalytic process, and the Prout-Tompkins model was modified according to the solubility curve in order to apply in solution crystallization.The autocatalytic kinetics of solvate crystallization was studied at different temperatures and initial concentrations.The effect of temperature was explained from two aspects:thermodynamics and nucleation mechanism.The kinetic parameters (activation energy E and pre-exponential factor k) of the autocatalytic kinetic models were estimated by multiple linear regression method.

Direct synthesis of H₂O₂ from H₂ and O₂ is a green process as compared to the conventional anthraquinone oxidation route.In this study, Pd/SiO₂ catalysts modified with pyridine were prepared for direct synthesis of H₂O₂.Comparing to Pd/SiO₂ catalyst, performance of pyridine modified Pd/SiO₂ for H₂O₂ formation was enhanced remarkably, and productivity of H₂O₂ increased by a factor of 3.For pyridine modified Pd/SiO₂ catalyst, the rate of H₂O₂ formation reached a maximum when the ratio of hydrogen to oxygen was 1:2.The structure of pyridine modified Pd/SiO₂ catalyst was characterized by using X-ray diffraction (XRD) and diffuses reflection infrared Fourier Transform spectra(DRIFTS).The changes in DRIFTS spectra indicated that Pd surface structure was significantly altered by pyridine, favoring H₂O₂ formation.

A 2-D-formulation of the mass balance equations for continuous annular chromatograph (CAC) is proposed.A numerical algorithm is developed to solve the coupled system of nonlinear convection diffusion equations in an iterative manner.The streamline diffusion method on an adaptively refined mesh is used to discretize the corresponding linear convection diffusion equations.The simulation with the mathematical model for CAC coincides with experimental data well.Profiles at the outlets in xylose-sorbose system show the robustness of the proposed algorithm over a wide range of design parameters.The model and algorithm are used to perform parametric calculations to investigate the influence of several model parameters on typical performance criteria for the chromatographic separation process.

Porous materials modified by amino can reach high CO₂ adsorption capacity.In this study, adsorbents were prepared by modifying polyethylene imine (PEI) and 2-amino-2-methyl-1-propanol (AMP) on pseudoboehmite.The effects of CO₂ pressure and content of PEI/AMP on CO₂ capacity were examined.Adsorbents were characterized by N₂ adsorption/desorption, scanning electron microscopy, and Fourier transform infrared spectroscopy.Experiment showed that at 50℃, the highest CO₂ adsorption capacity reached 77.53 mg CO₂·(g adsorbent)^-1, with PEI loading of 85% at reaction pressures≤1 MPa.For reaction pressures 1 MPa<P≤2 MPa, the highest CO₂ adsorption capacity of 123.79 mg CO₂·(g adsorbent)^-1 was obtained.For AMP loaded adsorbents, the highest CO₂ adsorption capacity was 128.01 mg CO₂·(g adsorbent)^-1 with AMP loading of 85%.Adsorption/desorption cycles showed that CO₂ capacity of adsorbents changed little.

Cross-linked polydimethylsiloxane (PDMS)/polyvinylidene fluoride (PVDF) composite nanofiltration (NF) membranes were prepared for recovery of hexane from soybean oil/hexane miscalls. Various reagents, such as tetraethoxylsilane (TEOS), phenyltrimethoxylsilane, octyltrimethoxylsilane and γ-aminopropyltriethoxylsilane, were used as cross-linking agents.Physical and chemical characteristics of the tailor made NF membranes were characterized by contact angle, FTIR, SEM, density, etc.The membranes were applied in the solvent recovery from soybean oil/hexane miscella.For each membrane, the effect of feed pressure upon the flux and oil retention was investigated.The permeate flux increases linearly with feed pressure, while oil retention increases first quickly and then slowly.With the increase of feed oil concentration, both flux and retention decrease significantly.It is found that the PDMS membrane cured with TEOS is the best for the separation.The observed osmotic phenomena similar to those of aqueous systems are interpreted using the van't Hoff equation.

Two novel aromatic diamines 3,5-diaminobenzophenone (PDA) and 4-(trifluoromethyl)phenyl 3,5-diaminobenzoate (FPDA) were mixed separately with 4,4'-diaminodiphenyl ether (ODA) and 3,5-diaminebenzoic acid (DABA) with different ratios, and then copolymerized separately with 4,4'-oxydiphthalic anhydride (ODPA), 3,3',4,4'-benzophenonetetracarboxylic dianhydride (BTDA) and 4,4'-(hexafluoroisopropylidene) diphthalic anhydride (6FDA) to give poly(amic acid)s, which were converted into cross-linked polyimides (PIs) with ethylene glycol (EG) by thermal imidization.The structures of these series of PIs were characterized by FT-IR, NMR and GPC.The effect of side-chain content on the thermal stability was investigated by DSC and TGA.The effects of the fluorine group on the properties and separation performance of side-chain polyimides were investigated.The membranes of polyimide obtained were employed in pervaporation separation of benzene/cyclohexane mixtures.The two side-chain polyimide membranes containing 6FDA have an optimal separation efficiency in terms of both flux and separation factor.The cross-linked 6FDA-FPDA/ODA/DABA (1:7:2) membranes show the most promising separation performance with a flux of 9.84 kg·μm·m^-2·h^-1 and separation factor of 6.1 for benzene/cyclohexane (50/50,mass ratio) at 50℃.

A sort of functional hydrophilic ionic liquid (ILs),[NH₂-C₃mim][Br],was prepared by the green synthesis route.Aiming at reduction of operational costs for CO₂ absorption and regeneration and reuse of absorbent,experiments on CO₂ capture and absorbent-desorption for regeneration and reuse were carried out.Experimental results showed that specific capacity of CO₂ (on the basis of complex absorbent or ILs component) changed with the concentration of ILs in the complex absorbent.In the initial stage,CO₂ absorption rates changed obviously with the concentration of ILs,and an appropriate ratio of complex absorbent was obtained(mass ratio of ILs to water was 1.38:1).Moreover,continuous CO₂ capture and absorbent regeneration experiments were carried out with a pilot scale equipment for absorption enhanced by super gravity field and desorption via counter-current contact under vacuum or by heating with water-based ionic liquid solution,improved hot potassium carbonate and activated complex alcamines as absorbent respectively.The results indicated good absorption for CO₂ capture with water-based ionic liquid solution,improved hot potassium carbonate and activated complex alcamines under super gravity field,and the absorption rates for CO₂ were 98%,96% and 90% respectively.Adsorbent could be regenerated and reused after CO₂ removal under vacuum or by heating.Water-based ionic liquid solution desorption under vacuum and at normal temperature was more practicable.

The extraction behavior of monochloroacetic acid and dichloroacetic acid with a mass ratio of 322:1 was investigated with trioctylamine(TOA)as the extractant and n-hexane as the diluent.The effects of temperature and initial concentrations of TOA on distribution coefficient were studied, and the mathematical models were proposed to describe the extraction equilibrium.The experimental results show that the effect of temperature on the distribution coefficient is small.The distribution coefficient for monochloroacetic acid increases with the concentration of TOA, while that of dichloroacetic acid increases first and then decreases as the concentration of TOA increases.Based on the apparent basicity of TOA in extraction, the mathematical model in single dichloroacetic acid system is proposed to describe the relationship between dichloroacetic acid and TOA.Further, the mathematical models in mix acid system are proposed based on the synergistic extraction.Therefore, it will be of great significance in industry.

An amine modified NiMgAl layered double hydroxide was synthesized via an exfoliation and grafting method.The samples were characterized by elemental analysis, X-ray diffraction, diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS), and thermogravimetric analysis (TGA).Adsorption of carbon dioxide on the modified layered double hydroxide was investigated by TGA at 25—150℃.NiMgAl N2 shows a maximum CO₂ adsorption capacity of 2.02 mmol·g^-1 in pure CO₂ and 1.89 mmol·g^-1 in 15% CO₂/N₂ at 80℃.The optimum desorption temperature is 140℃ for NiMgAl N2 according to adsorption/desorption experiments.By in-situ DRIFTS, the adsorption of CO₂ on NiMgAl N2 follows the mechanism of formation of ammonium carbamate ion pairs.

It is common to use multiple mini-hydrocyclones in parallel arrangement for large-scale industrial applications.For two typical parallel arrangements in mini-hydrocyclone group, U-U type and Z-Z type, the characteristics of pressure drop and flow distribution were investigated and compared by using theoretical model and experiments.It is found theoretically that the value of Q³+R² has great influence on the performance of both parallel arrangements, where Q and R represent the momentum and the friction effects.The performance of U-U arrangement is better if Q³+R²<0, while that of Z-Z arrangement is better if Q³+R²>0.The experimental results show that the Z-Z arrangement presents better pressure drop distribution than the U-U type for 0.05≤P<0.10 MPa, but the flow distribution of both parallel arrangements is non-uniform under the condition.At P=0.10 MPa, uniform pressure drop and flow distribution are found for both arrangements.For 0.10<P≤0.15 MPa, the flow distribution of U-U arrangement is more uniform than Z-Z type.The pressure drop distribution of both arrangements has the same trend and is good.

Oscillations are a common type of plant-wide disturbances in chemical process, which may impact overall process performance.Normally, the fault diagnosis methods only based on the amplitude domain of data have a poor performance on these problems.The method introduced, time delay analysis, based on the time domain knowledge of data, could establish the fault propagation path and identify the root cause of the oscillation.The innovation of this paper was to combine the Hopfield network and time delay analysis method and create a complete fault isolation strategy.The approach was applied to the Tennessee Eastman (TE) model and the result proved its good quality for industry application.

The polyethylene unit steam piping network system has a complex structure.It has various kinds of steam equipment, the parameters for the model are complicated and its energy consumption and configuration depend on experience.This paper puts forward the support vector machine as the soft sensor model to establish the accurate non-linear foundation model for the optimization of the steam piping network.A steam piping network model from the viewpoint of energy consumption was constructed based on material balance, energy conservation, and product quality.This model was a problem of mixed integer nonlinear programming (MINLP) calculated with adaptive mixed coding differential evolution (AMCDE).The polyethylene unit steam network of a petrochemical plant was simulated with the model and optimized.

Molecular weight and its distribution are extremely important quality indices in the polymer production process,however real-time measurement of molecular weight and its distribution cannot be achieved.Dynamic modeling based on polymerization mechanism is an important method for implementing soft measurement.In this study, the polymerization conditions of the ethylene slurry polymerization plant (HDPE) were investigated based on polymerization mechanism, with polymer average molecular weight and its distribution curve as the target, the ratio of hydrogen to ethylene in recycle gas as the decision variable.The results showed large deviation between the simulation results with the average molecular weight as the optimizing target and those of plant analysis.Although the average molecular weight of the polymer could reach the desired quality, the maximum error between the molecular weight distribution curve from simulation and the desired polymer product could be up to 0.092.However, the maximum error was only 0.069 with the molecular weight distribution curve as the target.Therefore,the optimization method with the molecular weight distribution curve as the target is significantly superior to the conventional optimization method with average molecular weight as the target.

The packed bed cell was used in the preparation of p-aminophenol from the electrochemical reduction of nitrobenzene.The effects of current density, flow rate of catholyte, reactor thickness and temperature on electrolysis were studied.The results showed that under the conditions of 10 mm thickness of copper mesh as cathode, DSA as anode, current density 1000 A·m^-2, flow rate of catholyte 4.28 cm·s^-1 and temperature 85℃, current efficiency for nitrobenzene reduction was almost 100%, and selectivity of p-aminophenol could reach 83%.The catholyte could be reused five times for electrolysis, which resulted in that the lowered consumptions of sulfuric acid and ammonia approximately to 25% of the original value, and reduced discharge amounts of ammonia sulfate and effluent by 75%.Diffusion dialysis was used to recycle sulfuric acid from the spent catholyte.The results showed that under the conditions of APS as anion exchange membrane, flow rate of simulated solution 0.01 ml·min^-1 and temperature 20℃, recovery of sulfuric acid was up to 61%, and transmissivities for p-aminophenol and aniline were only 1.4% and 1.6%, respectively.

A novel approach to modification of polypropylene microporous membrane (PPMM) surface based on molecular self-assembly and UV-crosslinking was devised.First, natural amphiphilic lecithin was introduced onto the PPMM surface via self-assembly.Then, a stable biomimetic surface analogy with phospholipid layer was constructed through UV-crosslinking of lecithin, conferring the PPMM surface with good hydrophilicity and biocompatibility.The anchoring of lecithin was confirmed by Fourier transformed infrared spectroscopy/attenuated total reflection(FTIR/ATR)and X-ray photoelectron spectroscopy (XPS) studies.Water contact angle, fluorescence labeled protein(FITC-protein)adsorption, and enzyme-linked immuno-sorbent assay (ELISA) were used to evaluate hydrophilicity and biocompatibility of the membrane.Water contact angle of the PPMMs surface was significantly improved after modification, by a decrease from 130? to 30?.Moreover, the modified membranes showed lower protein adsorption.Furthermore, the self-assembly and UV-crosslinking modified membrane exhibited good stability even after multiple washing compared with the self-assembly modified one.

Fractal geometry provides a mathematical formalism for describing complex spatial and dynamical structures.Therefore the enzyme molecules with irregular and self-similar structure can be studied thoroughly based on the fractal theory.In this paper the principle of box-counting dimension was used to investigate the impact of temperature and inhibitor on the structural changes of global enzymes and active sites of enzymes.The results suggested that the fractal dimension of enzyme molecule was greater than the fractal dimension of its active site.With increasing temperature, the calculated box-counting dimensions of global enzymes and their active sites all increased, especially for active sites.When enzyme was combined to the inhibitor, the dimensions of global enzymes did not change obviously, while the dimensions of active sites all decreased, indicating the decline of complexity for active sites.

To prepare the cellulose-based chromatography matrix with uniform size, a cross-flow microchannel chip was used to control the droplet size of cellulose solution and then the microdroplets were solidified to obtain the monodisperse cellulose beads.In the present work, ionic liquid,[EMIM]MP, was used to dissolve the microcrystalline cellulose as water phase and sunflower oil was used as oil phase.The effects of cellulose concentration, surfactant addition, flow rates of oil phase and water phase were investigated.The optimized preparation condition was 2% cellulose solution as water phase, flow rate of water phase of 6 μl·min^-1 and flow rate of oil phase of 200 μl·min^-1.The microdroplets of cellulose solution thus obtained could be about 100 μm with the variation coefficient less than 0.2.After solidification and regeneration, cellulose beads were obtained with good sphericity.Wet density of beads was 1.019 g·ml^-1, porosity was 94.6%, and mean size was about 105.5 μm.The cellulose beads were coupled with DEAE ligand and used as weak anion-exchange resin.The ion exchange capacity was 123.3 μmol·g^-1.Static adsorption and adsorption kinetics were studied.The results showed that saturated adsorption capacity for bovine serum albumin could reach 220 mg·g^-1, and the effective diffusion coefficient was 1.8×10^-11 m²·s^-1, which showed potential application for protein separation.

Production of biodiesel without byproduct glycerol using tiny KOH as catalyst from dimethyl carbonate and palm oil in supercritical conditions was carried out.The catalyst tiny KOH increased reaction rates while less severe supercritical reaction conditions could be employed.All components of reaction product were confirmed by GC and GC-MS analysis.Effects of temperature, time, mass ratio of KOH to palm oil and mole ratio of DMC to palm oil on transesterification reaction were investigated.The optimal conditions of transesterification are temperature 280℃, time 20 min, n(DMC):n(oil)=20:1 and m(KOH):m(oil)=0.1%, and at these conditions FAME yield was 83.11%.

To prove the feasibility that nano-scale porous membrane can replace ion exchange membrane used for vanadium redox flow battery(VRB), mass transfer of hydrated-ion in electrolyte solution through a limited space formed by PVDF nano-porous proton conductive membranes was studied.On a self-designed ion diffusion cell, NaCl and water permeation processes were measured under given concentration and hydrodynamic gradient, as well as osmotic pressure.The results obtained can be applied to correlate mass transport behaviors with membrane morphology.The results show that the behavior of ion diffusion through nano-scale limited space is similar to that in a bulk electrolyte solution; apparent diffusion coefficients are independent of ion concentration.In contrast, apparent diffusion coefficients of ion permeation through ion exchange membrane obviously increase with concentration gradient.For a given osmotic pressure, PVDF nano-porous proton conductive membranes have smaller water permeation rate than that of Nafion 117, and negative influence is also much smaller.Self-made PVDF proton conductive membrane can effectively reject VO²⁺, providing selectivity over 300 for H⁺/VO²⁺ electrolyte at ambient temperature, which means that it is possible to replace ion exchange membrane in flow battery application.

Hydrogen adsorption performance of a superactived carbon (Maxsorb) doped with Ni nanoparticles, prepared using plasma method, was studied.By comparing the material with sample prepared using traditional H₂ reduction, the effect of plasma on structure and performance of adsorbing H₂ of these samples was analyzed.The hydrogen storage capacity was significantly increased for plasma treatment samples.The H₂ storage capacity for Ni-doped Maxsorb at 298 K and 10 MPa was 1.17%(mass), and only 0.98%(mass) for H₂ reduction sample and 0.68% (mass) for pure Maxsorb one.Doping of Ni made storage capacity of carbon increase via hydrogen spillover mechanism.The sample with plasma treatment had smaller Ni particles that were highly dispersed on carbon.Meanwhile, it was found that there was stronger anchoring and more intimate contacts between metal and carbon.The increase of adsorption heat for the sample with plasma treatment suggests that the bonding between hydrogen atoms and the surface of Ni/Maxsorb was stronger, which was in agreement with high-pressure hydrogen adsorption results.

A series of polysulfone(PSf)/polyaniline-Pluronic F127(PANI-F127) composite ultrafiltration membranes, using two polymers namely PANI nanofibers and triblock copolymer Pluronic F127 with different modifying mechanisms as co-additives, were prepared via immersion precipitation method. The effects of the co-additives on membrane structure and performance were systematically investigated, compared and analyzed. Membrane structure was characterized by Fourier transform infrared spectroscopy(ATR-FTIR), X-ray photoelectron spectroscopy(XPS), energy dispersive X-ray spectroscopy(EDS), scanning electron microscope (SEM), porosity, and contact angle measurement. Membrane performance was evaluated by pure water flux, protein rejection, antifouling property and additive stability. Results demonstrate that Pluronic F127 was more effective in improving membrane hydrophilicity,while PANI nanofibers played an important role in increasing membrane porosity and decreasing surface pore size and skin layer thickness. Furthermore, it was found that the interaction between PANI nanofibers and Pluronic F127 has synergistic effects on improving membrane performance and depressing the defects such as large addition amount, low rejection and poor additive stability when using Pluronic F127 as the additive.

Using microfluidic technology to prepare silica microspheres with a bimodal pore structure can easily control pore structure and morphology.The silica microspheres with a bimodal pore structure were prepared by adjusting pH and temperature to improve gelation rate in the co-axial micro-channel.The effects of oil phase properties, flow rate of oil phase and gelation temperature on morphology and microstructure of the microspheres were investigated.Experimental results showed that the diameter of silica microspheres could be controlled between 300—600 μm, the specific surface area was about 1000 m²·g^-1, the pore diameter of mesopores was about 4—10 nm, and the pore diameter of macropores was about 400—1500 nm.Increase of flow rate of oil phase decreased particle size, accelerated rate of extraction of trioctylamine to hydrochloric acid, and then sped up the process of silica particle gel, making it easier to generate a loose mesh macroporous structure.High gelation temperature increased pore volume and pore size of the mesoporous pores.

Hydromagnesite is an important chemical raw material and product.A reactive crystallization method was provided to prepare hydromagnesite microspheres directly in experiments.The effects of stirring time, reactive temperature and reactant concentrations on the morphology and particle size were studied.The formation mechanism of hydromagnesite microspheres was analyzed.The results show that hydromagnesite microspheres with controllable size and good shape can be obtained by controlling the stirring time.The size of particles is 10—43 μm with the coefficient of variation of 28%—43%.It is found that the amorphous substance is first generated by the reaction of magnesium chloride and sodium carbonate in the crystallization process.The amorphous substance gradually transfers to crystal phase.The study shows that the stirring has a significant impact on the phase transfer of amorphous substance.Crystal nuclei form during the stirring process.Under the static condition, the growth process of amorphous substance onto the pre-existed crystals is dominant.As a result, the crystal size and morphology can be regulated by the stirring time.

Bulk polymerizations of 4,4'/2,4'-diphenylmethane diisocyanate/polytetramethylene ether glycol/1,4-butylene glycol without and with the addition of Bi/Zn composite catalyst were carried out to synthesize thermoplastic polyurethane (TPU) in a torque rheometry to simulate twin-screw extruder conditions, and the rheokinetics of polymerization process was investigated.The relations between torque and weight average molecular weight (M_W) of TPU were corrected based on two-dimensional flow simplification, correction between melt viscosity and molecular weight, and Arrhenius equation.The rheokinetics model was used to fit the variation of M_W of TPU during polymerization.The fitted M_W of TPU showed good agreement with that determined by gel permeation chromatography.The rheokinetic model could quickly provide real-time fitting results of M_W of TPU from the torque for the whole synthesis process.

The materials used here were isotactic polypropylene (iPP) produced by conventional slurry polymerization and under supercritical conditions.Wide-angle X-ray diffraction (WAXD) patterns of the iPPs obtained under various conditions were recorded to analyze the nascent polymorphic form.The effects of polymerization process, pre-polymerization temperature,particle size and molecular weight of the resultant iPPs on nascent polymorphic form were investigated.The iPP produced by supercritical polymerization was the mixture of α and γ forms while the iPP produced by conventional slurry process was only in the α form, just because, in the supercritical state of high pressure and high temperature, mass and heat transfer should be faster, which would facilitate development of nascent polymorphic form. Furthermore, pre-polymerization temperature, particle size and molecular weight of obtained iPPs were found to have significant effect on nascent crystallographic behavior.

Solid-phase transformation is a favorable method for preparation of Si substituted aluminophosphate molecular sieves (SAPO-5).The influence of temperature ramp rate and crystallization mode on the structure of SAPO-5 crystals was investigated by using XRD,SEM and EDS.Pure SAPO-5 phase could be synthesized with high (140℃·h^-1) and low (5.8℃·h^-1) temperature ramp rates.But SAPO-5 as well as SAPO-34 would be obtained with medium temperature ramp rates (17.5—70℃·h^-1).Crystallization mode affected obviously the morphology of SAPO-5.With medium temperature ramp rates,sphere-shaped and hexagonal plate-like SAPO-5 crystals were prepared under dynamic and static crystallization modes respectively.But the substitution mechanism of Si might be SM3 under both crystallization modes.However,crystallization mode did not influence the morphology of SAPO-5 prepared at high and low temperature ramp rates.Substitution mechanism of Si might be SM2 and SM3 under dynamic and static crystallization mode respectively.

A programmable torque rheometer was used for on-line determination of zero shear viscosity of solution copolymerization of acrylonitrile and itaconic acid in dimethylsulfoxide.The Arrhenius- Frenkel-Eyring equation was extended to identify the dependence of zero shear viscosity on polymer content, temperature and viscosity-average molecular weight of polyacrylonitrile.It was observed that under all of these process conditions, small differences in feed composition would give rise to a large variation on zero shear viscosity and ultimate viscosity to more than 100 Pa·s, so the control strategy for viscosity should be considered critically.The changes of reaction temperature seemed to be more effective than other methods.The viscosity increased quickly from about 2 mPa·s to 2—3 Pa·s in the first three hours under all experiment conditions which would greatly depress heat exchange and mixing efficiency.It was also found that viscosity increased dramatically as a result of gel effect when total overall monomer mass fraction was beyond 28% in feed.In addition, a small increase of polymer content could give rise to a great increase in viscosity when polymer content reached some critical values, which indicated that macromolecules were entangled severely in copolymerization solution.

A modified polyol method to prepare silver nanowires (AgNWs) is reported.AgNWs with uniform size and morphology were prepared in the presence of NiCl₂, MnCl₂ or FeCl₃ using high concentration silver nitrate solution (up to 0.4 mol·L^-1 in reaction solution).The diameters of the synthetic nanowires ranged from 60 to 100 nm and the lengths were about 30 to 60 μm.The influences of concentration of AgNO₃ solution, molar ratio of PVP to AgNO₃, and concentration of control agents were investigated.It was found that these conditions could be used to tune the morphology of resultant nanowires.The postulated mechanism relied on removal of adsorbed oxygen from crystal seeds surface by introduced metal cations, which facilitated the growth of AgNWs.

Polyethylene (PE) and its composite pipes have been widely used in the transportation of energy, such as natural gas and petroleum.Pipe welding joints have been proven to be a weak link of the whole pipeline.This means that non-destructive testing (NDT) and safety assessment of these joints are key technologies to guarantee safety of pipeline.In this paper, the theory and method of NDT technology on welding joint of PE pipes, inspection technique of cold welding and safety assessment of welding joints containing defects are introduced.Ultrasonic phased array and coupling focusing technology are applied in the inspection of electrofusion and butt-fusion joints of PE pipes respectively.Figures with inspecting image and cross section of practical joint are given.A cold welding inspection method based on ultrasonic phased array technology was invented, which has clear physics concept and is convenient in application.The defects in the electrofusion joints of PE pipe are classified into four categories:poor fusion interface, over welding, voids and structural deformity.Mechanical tests of joints with different kind of defects show that there are three main failure modes of EF joint under inner pressure, that is, cracking through the fusion interface, cracking through the fitting, and cracking through copper wire interface.A safety assessment method was proposed based on the experimental and analytical results.The proposed method can greatly improve intrinsical safety of such pipeline.