Hyperbranched polymer hollow-fiber-composite membranes for pervaporation separation of aromatic/aliphatic hydrocarbon mixtures

The separation of aromatic/aliphatic hydrocarbon mixtures is crucial in the petrochemical industry.Pervaporation is regarded as a promising approach for the separation of aromatic compounds from alkanes. Developing membrane materials with efficient separation performance is still the main task since the membrane should provide chemical stability, high permeation flux, and selectivity. In this study, the hyperbranched polymer(HBP) was deposited on the outer surface of a polyvinylidene fluoride(PVDF)hollow-fiber ultrafiltration membrane by a facile dip-coating method. The dip-coating rate, HBP concentration, and thermal cross-linking temperature were regulated to optimize the membrane structure.The obtained HBP/PVDF hollow-fiber-composite membrane had a good separation performance for aromatic/aliphatic hydrocarbon mixtures. For the 50%/50%(mass) toluene/n-heptane mixture, the permeation flux of optimized composite membranes could reach 1766 g·m^(-2)·h^(-1), with a separation factor of 4.1 at 60℃. Therefore, the HBP/PVDF hollow-fiber-composite membrane has great application prospects in the pervaporation separation of aromatic/aliphatic hydrocarbon mixtures.

Complete kinetic model for esterification reaction of lauric acid with glycerol to synthesize glycerol monolaurate

Glycerol monolaurate(GML)is a widely used industrial chemical with excellent emulsification and antibacterial effect.The direct esterification of glycerol with lauric acid is the main method to synthesize GML.In this work,the kinetic process of direct esterification was systematically studied using p-toluenesulfonic acid as catalyst.A complete kinetic model of consecutive esterification reaction has been established,and the kinetic equation of acid catalysis was deduced.The isomerization reactions of GML and glycerol dilaurate were investigated.It was found that the reaction was an equilibrium reaction and the reaction rate was faster than the esterification reaction.The kinetic equations of the consecutive esterification reaction were obtained by experiments as k_(1)=(276+92261Xcat)exp(-37720/RT)and k_(2)=(80+4413Xcat)exp(-32240/RT).The kinetic results are beneficial to the optimization of operating conditions and reactor design in GML production process.

Boosting kinetic separation of ethylene and ethane on microporous materials via crystal size control

The adsorptive separation of C_(2)H_(4)and C_(2)H_(6),as an alternative to distillation units consuming high energy,is a promising yet challenging research.The great similarity in the molecular size of C_(2)H_(4)and C_(2)H_(6)brings challenges to the regulation of adsorbents to realize efficient dynamic separation.Herein,we reported the enhancement of the kinetic separation of C_(2)H_(4)/C_(2)H_(6)by controlling the crystal size of ZnAtzPO_(4)(Atz=3-amino-1,2,4-triazole)to amplify the diffusion difference of C_(2)H_(4)and C_(2)H_(6).Through adjusting the synthesis temperature,reactant concentration,and ligands/metal ions molar ratio,ZnAtzPO4 crystals with different sizes were obtained.Both single-component kinetic adsorption tests and binary-component dynamic breakthrough experiments confirmed the enhancement of the dynamic separation of C_(2)H_(4)/C_(2)H_(6)with the increase in the crystal size of ZnAtzPO_(4).The separation selectivity of C_(2)H_(4)/C_(2)H_(6)increased from 1.3 to 98.5 with the increase in the crystal size of ZnAtzPO_(4).This work demonstrated the role of morphology and size control of adsorbent crystals in the improvement of the C_(2)H_(4)/C_(2)H_(6)kinetic separation performance.

Study on Adsorption Removal of Polycyclic Aromatic Hydrocarbons by Modified Mussel Shells

Polycyclic aromatic hydrocarbons(PAHs)are typical persistent organic pollutants(POPs)that are commonly found in the environment.They are carcinogenic,teratogenic,mutagenic and biodegradable obviously.In this paper,the modified mussel shells were used to adsorb and remove anthracene.The results show that the adsorption removal rate of the mussel shells was higher after calcination at 600℃.5%H_(3)PO_(4) solution was more suitable for shell treatment than 3 mol/L ZnCl_(2) solution.As the dosage of the modified shells was 0.5 g/L,the adsorption reached a stable state,and the removal rate of PAHs was about 69.44%;the adsorption efficiency rose with the increase of time.It can be seen that as a new and cheap biological adsorbent,the modified shells can be used to remove PAHs from wastewater.

Research on Catalytic Cracking Performance Improvement of Waste FCC Catalyst by Magnesium Modification

In this study,the deactivation mechanism caused by high accessibility of strong acid sites for the waste FCC catalyst was proposed and verified for the first time.Based on the proposed deactivation mechanism,magnesium modification through magnesium chloride impregnation was employed for the regeneration of waste FCC catalyst.The regenerated waste FCC catalyst was characterized,with its heavy oil catalytic cracking performance tested.The characterization results indicated that,in comparison with the unmodified waste FCC catalyst,the acid sites strength of the regenerated waste FCC catalyst was weakened,with no prominent alterations of the total acid sites quantity and textural properties.The heavy oil catalytic cracking results suggested that the catalytic cracking performance of the regenerated waste FCC catalyst was greatly improved due to the suitable surface acidity of the sample.In contrast with the unmodified waste FCC catalyst,the gasoline yield over the regenerated waste FCC catalyst significantly increased by 3.04 percentage points,meanwhile the yield of dry gas,LPG,coke and bottoms obviously decreased by 0.36,0.81,1.28 and 0.87 percentage points,respectively,making the regenerated waste FCC catalyst serve as a partial substitute for the fresh FCC catalyst.Finally,the acid property change mechanism was discussed.

Research on New Silica Sol Matrix Used in Fluid Catalytic Cracking Reaction

A new silica sol binder was obtained by mixing the acid-modified aluminium sulfate and water glass. The effect of SiO2 concentration in sodium silicate, pH value and polymerization was investigated. The new silica sol binder, which possessed abundant pore volume and suitable acid amount, was an ideal component for preparing cracking catalyst. As a result, the corresponding catalyst comprising the new binder showed excellent performance. Compared with the reference sample, the liquefied petroleum gas(LPG) and propylene yield obtained over this catalyst increased by 3.49 and 1.20 percentage points, respectively. The perfect pore structure and suitable Lewis acid amount of new silica sol were the possible reason leading to its outstanding performance.

Catalyst grading technology for promoting the diesel hydrocracking to naphtha

This paper reports the application of multi-component hydrocracking catalyst grading technology in diesel hydrocracking system to increase naphtha,and studies the influence of catalyst systems with different number of graded beds on the reaction process of diesel hydrocracking.Three hydrocracking catalysts with different physicochemical properties as gradation components,the diesel hydrocracking reaction on catalyst systems of one-component,two-component and three-component graded beds with different loading sequences are carried out and evaluated,respectively.The catalytic mechanism of the multi-component grading system is analyzed.The results show that,with the increase of the number of grading beds,the space velocity of reaction on each catalyst increases,which can effectively control the overreaction process;along the flow direction of feedstock,the loading sequences of catalysts with acidity decreasing and pore properties increasing can satisfy the demand of different catalytic activity for the conversion of reactant with changing composition to naphtha,which has a guiding role in the conversion of feedstock to target products.Therefore,the conversion of diesel,the selectivity and yield of naphtha all increase significantly on the multi-component catalyst system.The research on the grading technology of multi-component catalysts is of great significance to the promotion and application of catalyst systems in various catalytic fields.

Reaction characteristics of maximizing light olefins and decreasing methane in C_(5) hydrocarbons catalytic pyrolysis

When converting C_(5) hydrocarbons to light olefins by catalytic pyrolysis,the generation of low value-added methane will affect the atomic utilization efficiency of C_(5) hydrocarbons.To improve the atomic utilization efficiency,different generation pathways of light olefins and methane in the catalytic pyrolysis of C_(5) hydrocarbons were analyzed,and the effects of reaction conditions and zeolite types were inves-tigated.Results showed that light olefins were mainly formed by breaking the C_(2)-C_(3) bond in the middle position,while methane was formed by breaking the C_(1)-C_(2) bond at the end.Meanwhile,it was discovered that the hydrogen transfer reaction could be reduced by about 90%by selecting MTT zeolite with 1D topology and FER zeolite with 2D topology under high weight hourly space velocity(WHSV)and high temperature operations,thus leading to the improvement of the light olefins selectivity for the catalytic pyrolysis of n-pentane and 1-pentene to 55.12% and 74.60%,respectively.Moreover,the fraction ratio of terminal C_(1)-C_(2) bond cleavage was reduced,which would reduce the selectivity of methane to 6.63%and 1.83%.Therefore,zeolite with low hydrogen transfer activity and catalytic pyrolysis process with high WHsV will be conducive to maximize light olefins and to decrease methane.

Elucidating the effect of oxides on the zeolite catalyzed alkylation of benzene with 1-dodecene

In the present work, the effect of oxides on the alkylation of benzene with 1-dodecene was comprehensively investigated over MCM-49 n-heptanol, n-heptaldehyde and n-heptanoic acid were selected as the model oxides herein, and obvious decrease of lifetime could be caused by only trace amount of oxides added in the feedstocks. However, the deactivated catalysts were difficult to be regenerated by extraction with hot benzene. Additionally, coke-burning was also proved to be incapable to regenerate the deactivated catalysts mainly for the dealumination during calcination. Further characterizations complementary with DFT calculations were conducted to demonstrate that the deactivation was mainly due to the firm adsorption of oxides on the acid sites.

PtCo-based nanocatalyst for oxygen reduction reaction:Recent highlights on synthesis strategy and catalytic mechanism

Oxygen reduction reaction over Pt-based catalyst is one of the most significant cathode reactions in fuel cells.However,low reserves and high price of Pt have motivated researchers worldwide seeking enhanced utilization efficiency and durability by doping non-noble metals to form Pt-based alloy catalysts.Alloying Pt with Co has been recognized as one of the most effective approaches to achieve this goal.PtCo bimetal combination is one of the most promising candidates to synthesize highly efficient catalysts for oxygen reduction reaction(ORR)applications,owing to its relatively more suitable oxygen binding energy for four-electron transfer reactions.Recently,impressive strategies have been developed to fabricate more active and stable PtCo-based multimetallic alloys with tailorable size and morphology.This paper aims to summarize the most recent highlights on the study of the relationship between preparation strategies,morphologies,electroactivities of the PtCo-based catalyst at atomic level and further the relevant reaction mechanism.The challenges and opportunities on the further development of electrocatalysts for fuel cells are included to provide reference for the practical application.

Determination of the Henry’s Law Constant of Hexane in High-Viscosity Polymer Systems

The Henry’s law constant of volatiles in polymer systems is a crucial parameter reflecting the gas-liquid equilibrium,which is very important for devolatilization.In this research,polyolefin elastomer(POE)-cyclohexane and polydimethylsiloxane(PDMS)-hexane systems were studied,and the Henry’s law constant was obtained by measuring the gas phase equilibrium partial pressure when polymer solutions containing different mass fractions of volatiles reached a saturated state.The effects of temperature,type of volatiles,and polymer viscosity on the gas phase equilibrium partial pressure and Henry’s law constant of the volatiles were investigated.The results indicate that,with the increase of temperature and polymer viscosity,the gas phase equilibrium partial pressure and Henry’s law constant of volatiles increase.As temperature increases,the solubility of gas in liquid decreases.The relationship between the Henry’s law constant and temperature is consistent with the Arrhenius law.In the PDMS-hexane system,the gas phase equilibrium partial pressure and Henry’s law constant of n-hexane are higher than those of cyclohexane.The obtained Henry’s law constants can be used as a reference for perfecting the devolatilization process and improving the devolatilization effect.

Hydrothermally stable mesoporous aluminosilicates as superior FCC catalyst:From laboratory to refinery

Well-ordered aluminosilicates(MAs)were prepared by in-situ assembly of pre-crystallized units of zeolite Y precursors at a commercial scale,and applied in an industrial fluid catalytic cracking unit for the first time.Compared with incumbent equilibrium catalyst,the surface area of trial equilibrium catalysts(30%inventory ratio)increased from 110 m^(2)g^(-1)to 120m^(2)g^(-1).Moreover,a significant increase of the mesoporous surfaceareaof trial equlibrium catalysts(30%inventoryrati)from 33 m g/to 40magi(22%increase).Furthermore,the equilibrium catalyst that contain 80%LPC-65 yields significantly lower heavy oil(0.23%)and higher total liquids(0.53%)compared with LDO-70.The industrial results demonstrated excellent hydrothermal stability and superior catalytic cracking properties,showing the promising futurein the industrial units.

Hollow ZSM-5 encapsulated with single Ga-atoms for the catalytic fast pyrolysis of biomass waste

The development of efficient metal-zeolite bifunctional catalysts for catalytic fast pyrolysis(CFP) of biomass waste is highly desirable for bioenergy and renewable biofuel production.However,conventional metal-loaded zeolites often suffer from metal sintering during pyrolysis and are thus inactivated.In this study,single-site Ga-functionalized hollow ZSM-5(GaO_x@HS-Z5) was synthesized via an impregnationdissolution-recrystallization strategy without H_(2) reduction.The Ga atom was coordinated to four oxygen atoms in HS-Z5 frameworks.Benefitting from the highly dispersed single-Ga atoms and hollow zeolite framework,3GaO_x@HS-Z5 performed the best in producing hydrocarbon-rich bio-oil compared to impregnated 3GaO_x/HS-Z5 and H_(2)-reduced 3Ga@HS-Z5 in the maize straw CFP.In particular,3GaO_x@HS-Z5 delivered the highest bio-oil yield(23.6 wt%) and hydrocarbon selectivity(49.4 area%).3GaO_x@HS-Z5 also retained its structural integrity and catalytic activity after five pyrolysis-regeneration cycles,demonstrating its advantage in practical biomass CFP.The elimination of H_(2) reduction during the synthesis of catalyst provides an additional advantage for simplifying the CFP process and reducing operating costs.The retained Ga micro-environment and anti-sintering properties were unique for 3GaO_x@HS-Z5,as severe metal sintering occurred during pyrolysis for other metals(e.g.,NiO_x,ZnO_x,FeO_x,and CoO_x) that encapsulated HS-Z5.

Mixing of miscible shear-thinning fluids in a lid-driven cavity

The concentration and velocity fields of two refractive index matched miscible shear-thinning fluids in a lid-driven cavity were investigated by using planar laser-induced fluorescence and particle image velocimetry,as well by computational fluid dynamics.Quantitative analyses show that the results obtained by flow simulations with the species transport model are in good agreement with the experimental results.The effects of different parameters were studied by using the intensity of segregation.For two fluids with the same rheological parameters,the relative amounts of liquids H_(1)/H and the power-law index n dominate the mixing process while the Reynolds number Re plays a marginal role.As for two fluids with density difference,buoyancy has significant influence on the mixing process.The dimensionless group Ar/Re(redefined such as to include shear thinning behavior)is proposed for assessing the effect of buoyancy and rheological properties on the mixing of miscible shear-thinning fluids.

Preparation of Core-Shell Composite of Y@Mesoporous Alumina and Its Application in Heavy Oil Cracking

A well core-shell composite of Y@meso-Al with a mesoporous alumina shell and a Y zeolite core was synthesized. The mesoporous alumina shell has a wormhole-like structure with large mesopores. The prepared catalytic cracking catalyst using this composite has exhibited excellent catalytic performance for heavy oil cracking thanks to its favorable physicochemical properties, such as high surface area, large pore volume and outstanding acid sites accessibility for large molecules provided by the composite. In comparison with the reference catalyst using pure Y zeolite, the oil conversion achieved by the above-mentioned catalyst increased by 2.73 percentage points, while the heavy oil yield and coke yield decreased by 2.23 percentage points and 1.28 percentage points, respectively, with the light oil yield increasing by 2.27 percentage points.

Hydrocracking diversity in n-dodecane isomerization on Pt/ZSM-22 and Pt/ZSM-23 catalysts and their catalytic performance for hydrodewaxing of lube base oil

Nobel metallic Pt/ZSM-22 and Pt/ZSM-23 catalysts were prepared for hydroisomerization of normal dodecane and hydrodewaxing of heavy waxy lube base oil.The hydroisomerization performance of n-dodecane indicated that the Pt/ZSM-23 catalyst preferred to crack the C-C bond near the middle of n-dodecane chain,while the Pt/ZSM-22 catalyst was favorable for breaking the carbon chain near the end of n-dodecane.As a result,more than 2%of light products(gas plus naphtha)and3%more of heavy lube base oil with low-pour point and high viscosity index were produced on Pt/ZSM-22 than those on Pt/ZSM-23 while using the heavy waxy vacuum distillate oil as feedstock.

Preparation of phosphorus-modified PITQ-13 catalysts and their performance in 1-butene catalytic cracking

A series of phosphorus-modified PITQ-13 catalysts was prepared by wet impregnation of NH4H2PO4 solution into an HITQ-13 parent. The catalysts were characterized using XRD, N2 adsorption, MAS NMR and NH3-TPD. Their catalytic performance in 1-butene catalytic cracking was evaluated in a fixed fluidized bed reactor. The results showed that the crystallinity, surface area and pore volume of P-modified PITQ-13 catalysts decreased with the increasing amounts of P. The number of weak acid sites increased, whereas that of strong acidity decreased. The selectivity to propylene in 1-butene cracking reactions increased because of the decrease in strong acidity. The yield of propylene achieved 41.6% over PITQ-13-2 catalyst with a P content of 1.0 wt%, which was 5.1% greater than that achieved over HITQ-13 catalyst.

Hydroisomerization performance of platinum supported on ZSM-22/ZSM-23 intergrowth zeolite catalyst

Hydroisomerization catalysts Pt/ZSM-22, Pt/ZSM-23, and Pt/ZSM-22/ZSM-23 were prepared by supporting Pt on ZSM-22, ZSM-23, and intergrowth zeolite ZSM-22/ZSM-23, respectively. The typical physicochemical properties of these catalysts were characterized by X-Ray Diffraction （XRD）, N2 absorption-desorption, Pyridine-Fourier Transform Infrared （Py-FTIR）, Transmission Electron Microscopy （TEM）, X-Ray Fluorescence （XRF）, Scanning Electron Microscopy （SEM） and NH3- Temperature Programmed Desorption （NH3-TPD）, and the performance of these catalysts in n-dodecane hydroisomerization was evaluated in a continuous down-flow fixed bed with a stainless steel tubular reactor. The characterization results indicated that the intergrowth zeolite ZSM-22/ZSM-23 possessed the dual structure of ZSM-22 and ZSM-23, and the catalyst Pt/ZSM-22/ZSM-23 had similar pores and weak acidity to Pt/ZSM-22 and Pt/ZSM-23 catalysts. Moreover, Pt/ZSM-22/ZSM-23 catalyst showed a high selectivity in hydroisomerization of long chain n-alkanes to mono-branched isomers. The evaluation results for n-dodecane hydroisomerization indicated that the activity of Pt/ZSM-22/ZSM-23 was the lowest, while the hydroisomerization selectivity was the highest among the three catalysts. The maximum yield of i-dodecane product was 68.3% over Pt/ZSM-22/ZSM-23 at 320 ℃.

Bis(trifluoromethylsulfonyl)phenylamines as Internal Donors for Ziegler-Natta Polymerization Catalysts

几二度(trifluoromethylsulfonyl ) phenylamines 被综合了并且为丙烯聚合为异构的 Ziegler-Natta 催化剂的准备用作内部施主。这些新催化剂是高度活跃的并且在有为丙烯的聚合的一个外部施主的联合的 stereospecific。这些催化剂的活动被苯基取代者的电子能力戏剧性地在 sulfonyl phenylamines 上影响。因此，催化剂的表演能被调整 sulfonyl phenylamines 的苯基取代者的电子性质修改。

Application of New Heavy Metals Resistant Porous Binder Material Used in Fluid Catalytic Cracking Reaction

A novel porous binder was obtained from acid-treated kaolin. This new binder possessed abundant meso/macropores, good hydrothermal stability and heavy metal resistance. The prepared catalyst using new binder featured low attrition index and large pore volume. The catalysts were contaminated with Ni, V, and tested in a fixed-fluidized bed reactor unit. In comparison with the reference sample, the oil conversion achieved by the above-mentioned catalyst increased by 3.50 percentage points, and heavy oil yield decreased by 2.86 percentage points, while the total liquid yield and light oil yield increased by 2.82 percentage points and 0.79 percentage points, respectively. The perfect pore structure, good hydrothermal stability and heavy metal resistant performance of new binder were the possible causes leading to its outstanding performance.