Numerical simulation of multiphase flows in processing equipment in industry with two-fluid models and Eulerian-Lagrangian approaches requires the constitutive equations describing the interactions between the dispersed phase of high concentration and the continuous phase.The status of research on the forces on dispersed solid and fluid particles is reviewed in this article.As compared with the knowledge on drag of single solid particles,study on particle swarms and on other forces is not sufficient to meet the demand of reliable and efficient numerical simulation of multiphase flows.Thus,thorough study on the particle swarms becomes the key to accurate multi-scale simulation of multiphase flows.Besides,the development of efficient algorithm dealing with the non-uniformity on both equipment and mesoscopic scales is recognized as an important issue to be resolved.The research topics in the near future are suggested.

Micromixing efficiency of viscous media in Y-type micro-channel reactor was studied by using iodide-iodate test reaction as working system.Experiments were carried out in water-glycerin mixtures with 7 different viscosities.The experimental results showed that segregation index of the micro-channel reactor increases with the decrease of volumetric flow rate and the increase of solution viscosity.Based on the incorporation model,the micromixing time tm of the micro-channel reactor was estimated in the range of 10^-4-10^-3s at different viscosities,which indicated that the micro-channel reactor possesses a much better micromixing performance compared to the stirred tank(tm=0.02-0.2s).

Boiling of water/triethyleneglycol(TEG) binary solution has a wide-ranging application in the gas processing engineering.Design,operation and optimization of the involved boilers require accurate prediction of boiling heat transfer coefficient between surface and solution.In this investigation,nucleate pool boiling heat transfer coefficient has been experimentally measured on a horizontal rod heater in water/TEG binary solutions in a wide range of concentrations and heat fluxes under ambient condition.The present experimental data are correlated using major existing correlations.In addition a correlation is presented for prediction of pool boiling heat transfer for the system in which the vapour pressure of one component is negligible.This model is based on the mass transfer rate equation for prediction of the concentration at the bubble vapor/liquid interface.Based on this prediction,the temperature of the interface and accordingly,the boiling heat transfer coefficient could be straightforwardly calculated from the known concentration at the interface.It is shown that this simple model has sufficient accuracy and is acceptable below the medium concentrations of TEG when the vapor equilibrium concentration of TEG is almost zero.The presented model excludes any tuning parameter and requires very few physical properties to apply.

According to the configuration,mixed-conducting membranes are classified as symmetric membranes and asymmetric membranes consisting of a thin dense layer and a porous support.In this study,these two kinds of SrCo_0.4Fe_0.5Zr_0.1O_3-δ oxide-based membranes were systematically compared in terms of oxygen permeability and chemical stability,and their differences were elucidated by means of the theoretical calculation.For the oxygen permeability,the asymmetric membrane was greater than the symmetric membrane due to the significant decrease of bulk diffusion resistance in the thin dense layer of the asymmetric membrane.In regard to the chemical stability,the increase of oxygen partial pressure on the asymmetric membrane surface at CH₄ side produced the stable time of over 1032h in partial oxidation of methane at 1123K,while the symmetric membrane was only of 528h.This study demonstrated that the asymmetric membrane was a promising geometrical configuration for the practical application.

To get more accurate kinetic data of the absorption of CO₂ into aqueous solution of N-methyldiethanolamine,a wetted wall column was modified to more uniformly distribute the liquid on the column surface and gas in the absorbing chamber and change the length of the column.The average liquid film thickness and the liquid-phase mass transfer coefficient were measured,and a correlation for the Sherwood number,Reynolds number and Schmidt number was obtained for the modified wetted wall column.The equilibrium concentrations in chemical reactions were calculated with a minor absolute error for calculating the rate constant more accurately.A mathematical model for the CO₂ absorption was established based on the diffusional mass transfer accompanied with parallel reversible reactions,and the partial differential equation was solved by Laplace transform.An analytical expression for the concentration of carbon dioxide as a function of time and penetration depth in liquid film and the average interphase mass transfer rate was obtained.This model was also used to calculate the rate constant for a second-order reaction,which was in good agreement with reported data.

A systematic molecular simulation study was performed to investigate the effect of catenation on methane adsorption in metal-organic frameworks(MOFs).Four pairs of isoreticular MOFs(IRMOFs) with and without catenation were adopted and their capacities for methane adsorption were compared at room temperature.The present work showed that catenation could greatly enhance the storage capacity of methane in MOFs,due to the formation of additional small pores and adsorption sites formed by the catenation of frameworks.In addition,the simulation results obtained at 298K and 3.5MPa showed that catenated MOFs could easily meet the requirement for methane storage in porous materials.

The adsorption of uranium(Ⅵ) on the manganese oxide coated zeolite(MocZ)from aqueous solution was investigated in a fixed-bed column.The experiments were conducted to investigate the effects of bed height,flow rate,particle size,initial concentration of uranium(Ⅵ),initial pH,presence of salt and competitive ions.The U-uptake by MocZ increased with initial uranium(Ⅵ)concentration and bed height,but decreased as the flow rate and particle size increased.In the presence of salt and competitive ions,the breakthrough time was shorter.The adsorption capacity reached a maximum at pH of 6.3.The Thomas model was applied to the experimental data to determine the characteristic parameters of the column for process design using linear regression.The breakthrough curves calculated from the model were in good agreement with the experimental data.The BDST model was used to study the influence of bed height on the adsorption of uranium(Ⅵ).Desorption of uranium(Ⅵ)in the MocZ column was investigated.The column could be used for at least four adsorption-desorption cycles using 0.1mol·L^-1 NaHCO³ solution as the elution.After desorption and regeneration with deionized water,MocZ could be reused to adsorb uranium(Ⅵ)at a comparable capacity.Compared to raw zeolite,MocZ showed better capacity for uranium(Ⅵ)removal.

Permeabilities and selectivities of gases such as carbon dioxide(CO₂),sulfur dioxide(SO₂),nitrogen(N₂)and methane(CH₄)in six imidazolium-based ionic liquids([emim][BF₄],[bmim][BF₄],[bmim][PF₆₄],[bmim][Tf₂N]and[emim][CF₃SO₃])supported on polyethersulfone microfiltration membranes are investigated in a single gas feed system using nitrogen as the environment and reference component at temperature from 25 to 45℃ and pressure of N₂₂ has the highest permeability in the tested supported ionic liquid membranes,being an order of magnitude higher than that of CO₂,and about 2 to 3 orders of magnitude larger than those of N₂ and CH₄.The observed selectivity of SO₂ over the two ordinary gas components is also striking.It is shown experimentally that the dissolution and transport of gas components in the supported ionic liquid membranes,as well as the nature of ionic liquids play important roles in the gas permeation.A nonlinear increase of permeation rate with temperature and operation pressure is also observed for all sample gases.By considering the factors that influence the permeabilities and selectivities of CO₂ and SO₂,it is expected to develop an optimal supported ionic liquid membrane technology for the isolation of acidic gases in the near future.

A model for one-dimensional unsteady heterogeneous mass transfer was developed based on Danckwerts' surface renewal theory in order to describe the mass transfer enhancement of absorption process for a slightly soluble gas in a gas-liquid-liquid system.The model accounts for the mass transfer resistance within the dispersed phase and the effect of emulsion viscosity on mass transfer.An analytical solution for enhancement factor was obtained by Laplace domain transformation.The absorption rates of carbon dioxide in the dodecane-in-water and castor oil-in-water systems were measured in a thermostatic reactor,and the enhancement factors were calculated at different volume fractions of dispersed phase and stirrer speeds.The model predictions agree well with the experimental data.

Benzoic acid residue is solid waste produced from the production of benzoic acid by oxidizing toluene.Because it contained important chemical raw materials such as benzoic acid,benzyl benzoate and fluorenone,it is necessary to recover them from the residue.In this work the technique featured with high efficiency evaporation and vacuum distillation was developed to obtain total recovery and utilization of the benzoic acid residue.By controlling the operation temperature at 260℃ and the pressure of 16kPa in the rising and falling film evaporators,heavy components separated efficiently from the residue can be polymerized and the light components consisting of 63% of the residue entered into a benzoic acid vacuum distillation column.Keeping the temperature of polymerization at(280±10)℃,coumarone resin was produced after adjusting the softening point according to the market requirements.Vacuum distillation was operated under the following conditions:top temperature at 186℃,top pressure of 16kPa,bottom temperature at 240-250℃,reflux ratio being 3:1.Benzoic acid of 98% purity was distilled out from the column as a side stream and the bottom product was crude benzyl benzoate.By the developed technique,the benzoic acid residue was splitted into three products,benzoic acid,crude benzyl benzoate and coumarone resin without any surplus waste.

Liquid phase oxidation of toluene is an environmental benign route for the production of benzoic acid.In a ø48mm bubble column reactor,the commercial process of toluene liquid phase oxidation was conducted with Co(CH₃COO)₂.4H₂O as catalyst.The Co²⁺ concentration [Co²⁺] was determined by extraction spectrophotometry and hereby the Co³⁺ concentration [Co³⁺] was obtained by mass balance.The results showed that [Co³⁺] reached the maximum at about 25-30min.[Co³⁺] increased with increasing Co catalyst amount at total Co concentration<150 mg·L^-1 of toluene.The conversion of toluene,yield and selectivity of benzoic acid increased with the increasing [Co³⁺+/Co²⁺] max.A high [Co³⁺] and a high [Co³⁺]/[Co²⁺] ratio are beneficial to the reaction.

In the article the Grand Canonical Monte Carlo(GCMC),molecular dynamics(MD),and kinetic Monte Carlo(KMC)simulations with particular focus on ascertaining the loading dependence of benzene diffusion in the zeolite were performed.First,a realistic representation of the structure of the sorbate-sorbent system was obtained based on GCMC simulation.The simulation clearly shows the characteristics of the adsorption sites of the benzene-NaY system,from which two kinds of preferably adsorbing sites for benzene molecules,called S_Ⅱ and W sites,are identified.The structure thus obtained was then used as a basis for KMC and MD simulations.A comparative study by introducing and comparing two different mechanisms underlying jump diffusion in the zeolite of interest shows that the MS diffusivity values predicted by the KMC and MD methods are fairly close to each other,leading to the conclusion that for benzene diffusion in NaY,the S_Ⅱ→W→S_Ⅱ jumps of benzene molecules are dominated,while the W→W jumps do not exist in the process.These findings provide further support to our previous conclusion about the absence of the W→W jumps in the process of benzene diffusion in NaY.Finally,two relations for predicting the self-and MS diffusivities were derived and found to be in fair agreement with the KMC and MD simulations.

Conversion of methane by steam reforming was carried out by means of dielectric-barrier discharge.A systemic procedure was employed to determine the suitable experimental conditions.It was found that one of the plasma generators can match the system best.A higher power input can always bring a higher conversion,but the selectivity to C₂H₆ decreased from 52.48% to 39.43% as the power increased from 20W to 49W.When discharge distance was 4mm,selectivities to almost all main products reached the max.The inner electrode made of stainless steel and the outer electrode with aluminum foil were one of the best options which can obviously enhance the conversion of methane.A larger flow rate always resulted in a lower conversion of methane.In the most time,19.93% steam promoted conversion of methane.

One-dimensional heterogeneous plug flow model was employed to model an adiabatic fixed-bed reactor for the catalytic dehydration of methanol to dimethyl ether.Longitudinal temperature and conversion profiles predicted by this model were compared to those experimentally measured in a bench scale reactor.The reactor was packed with 1.5mm γ-Al₂O₃ pellets as dehydration catalyst and operated in a temperature range of 543-603K at an atmospheric pressure.Also,the effects of weight hourly space velocity(WHSV)and temperature on methanol conversion were investigated.According to the results,the maximum conversion is obtained at 603.15K with WHSV of 72.87h^-1.

Phase equilibrium conditions of gas hydrate in several systems were measured by the step-heating method using the cylindrical transparent sapphire cell device.The experimental data for pure CH₄ or CO₂+deionized water systems showed good agreement with those in the literatures.This kind of method was then applied to CH₄/CO₂+sodium dodecyl sulfate(SDS)aqueous solution,CH₄/CO₂+SDS aqueous solution+silica sand,and(CH₄+C₂MH₆C₃H₈)gas mixture+SDS aqueous solution systems,where SDS was added to increase the hydrate formation rate without evident influence on the equilibrium conditions.The feasibility and reliability of the step-heating method,especially for porous media systems and gas mixtures systems were determined.The experimental data for CO₂+silica sand data shows that the equilibrium pressure will change significantly when the particle size of silica sand is less than 96μm.The formation equilibrium pressure was also measured by the reformation of hydrate.

Vapor-liquid phase equilibrium data including composition,densities,molar volume and equilibrium constant of isobutanol in supercritical carbon dioxide from 313.2K to 353.2K were measured in a variable-volume visual cell.The properties of critical point were obtained by extrapolation.The results showed that critical temperature,critical pressure and critical compressibility factor of CO²-isobutanol system decreased with the increase of critical COM² content.The phase equilibrium model was established by Peng-Robinson equation of state and van der Waals-2 mixing regulation,and model parameters were determined by optimization calculation of nonlinear least square method.The correlation between calculated values and the experimental data showed good agreement.

This research is focused on the development of a simple design model of the submerged catalysis/membrane filtration(catalysis/MF)system for phenol hydroxylation over TS-1 based on the material balance of the phenol under steady state and the reported kinetic studies.Based on the developed model,the theoretical phenol conversions at steady state could be calculated using the kinetic parameters obtained from the previous batch experiments.The theoretical conversions are in good agreement with the experimental data obtained in the submerged catalysis/MF system within relative error of±5%.The model can be used to determine the optimal experimental conditions to carry out the phenol hydroxylation over TS-1 in the submerged catalysis/MF system.

The presence of salt has a profound effect on the size,shape and structure of sodium dodecyl sulfate(SDS)micelles.There have been a great number of experiments on SDS micelles in the presence and absence of salt to study this complex problem.Unfortunately,it is not clear yet how electrolyte ions influence the structure of micelles.By describing the compromise between dominant mechanisms,a simplified atomic model of SDS in presence of salt has been developed and the molecular dynamics(MD)simulations of two series of systems with different concentrations of salt and charges of ion have been performed.Polydispersity of micelle size is founded at relatively high concentration of SDS and low charge of cation.Although the counterion pairs with head groups are formed,the transition of micelle shape is not observed because the charge of cation is not enough to neutralize the polar of micelle surface.

Homogeneous(unseeded)precipitation of magnesium carbonate hydrates by the reaction of MgCl² with Na²CO³ in supersaturated solutions between 273 and 363K was investigated.The compositions,morphologies and filtration characteristics of the precipitates were studied in detail.The magnesium carbonate hydrates obtained at 313K and in the range of 343-363K showed good morphologies and filtration characteristics.Magnesium oxides(MgO)with high purity(97.6%-99.4%)were obtained by calcining magnesium carbonate hydrates at 1073K.

Hydroxyapatite coatings were directly prepared on anodized titanium by electro-deposition method in a modified simulated body fluid.The configuration,structure and bioactivity of the coating were investigated with scanning electron microscopy(SEM),X-ray diffraction analyzer(XRD)and Fourier transform infrared spectroscopy(FTIR)techniques.The results demonstrated that pure and homogeneous hydroxyapatite coating can be obtained without any post-treatment.The prepared coating showed good bioactivity in simulated body fluid(SBF).The time required for a fully covered dense hydroxyapatite coatings was 4 days immersion in SBF.

Lutein was nano-encapsuled with hydroxypropylmethyl cellulose phthalate(HPMCP) to maintain its bioactivity and to avoid thermal/light degradation.Supercritical antisolvent precipitation was applied to prepare lutein/HPMCP nano-capsule.The effects of several operating parameters on the yield,lutein loading,encapsulation efficiency,particle size and particle size distribution of the nanocapsule were investigated.The mean diameter of nanocapsules ranged from 163nm to 219nm under appropriate experimental conditions.The result of scanning electron microscope showed that the nanocapsules were nearly spherical.The highest yield reached 95.35% when the initial concentration of lutein was saturated.The highest lutein loading of 15.80% and encapsulation efficiency of 88.41% were obtained under the conditions of 11MPa,40℃ and C_HPMCP:C_lutein=5:l.The results may promote the application of lutein in food industry.

Expanded bed adsorption(EBA),a promising and practical separation technique,has been widely studied in the past two decades.The development of adsorbents for EBA process is a challenging course,with the special design and preparation according to the target molecules and specific expanded bed systems.Many types of supporting matrices for expanded bed adsorbents have been developed,and their preparation methods are being consummated gradually.These matrices are activated and then coupled with ligands to form functionalized adsorbents,including ion-exchange adsorbents,affinity adsorbents,mixed mode adsorbents,hydrophobic charge induction chromatography adsorbents and others.In this review,the preparation of the matrices for EBA process is summa-rized,and the coupling of ligands to the matrices to prepare functionalized adsorbents is discussed as well.

Fluidized beds enable good solids mixing,high rates of heat and mass transfer,and large throughputs,but there remain issues related to fluidization quality and scale-up.In this work I review modification techniques for fluidized beds from the perspective of the principles of process intensification(PI),that is,effective bubbling suppression and elutriation control.These techniques are further refined into(1)design factors,e.g.modifying the bed configuration,or the application of internal and external forces,and(2)operational factors,including altering the particle properties(e.g.size,density,surface area)and fluidizing gas properties(e.g.density,viscosity,or velocity).As far as two proposed PI principles are concerned,our review suggests that it ought to be possible to gain improvements of between 2 and 4 times over conventional fluidized bed designs by the application of these techniques.

A new method of upgrading 6# solvent oils using different ionic liquids as catalysts in a continuous apparatus is studied in this paper.The results show that aromatics,olefins and small quantity of sulfurs can be removed simultaneously.Using complex ionic liquid modified with CuCl as catalyst,olefins are removed completely,the mass concentrations of aromatics and sulfurs in solvent oil are 0.36% and 0.0058%,respectively,and the bromic index is zero.The sulfur removal rate decreases gradually with increasing of running time.The refined 6# solvent oil is corresponded to the quality standards of GB16629-1996,which request that the mass concentrations of aromatics,sulfurs and bromic index are 1%,0.012% and 1000,respectively.The loss of solvent oil is less than 3%.

Worldwide environment has resulted in a limit on the sulfur content of gasoline.It is urgent to investigate the desulfurization of gasoline.The polydimethylsiloxane(PDMS)/polyetherimide(PEI)composite membranes were prepared by casting a PDMS solution onto porous PEI substrates and characterized by scanning electron microscope(SEM).The membranes were used for sulfur removal from gasoline by pervaporation.The effects of feed temperature,sulfur content in the feed and PDMS layer thickness on membrane performance were investigated,and an activation energy of permeation was obtained.Experimental results indicated that higher feed temperature yielded higher total flux and lower sulfur enrichment factor.The total flux varied little with the increase of sulfur content in the feed,but the sulfur enrichment factor first increased with the amount of thiophene added into the gasoline,and then the variation was little.The increase of PDMS layer thickness resulted in a smaller flux but a larger sulfur enrichment factor.The result indicates that the PDMS/PEI composite membranes are promising for desulfurization by pervaporation.