The decomposition kinetics of glucose was studied in high-temperature liquid water （HTLW） from 180 to 220℃ under a pressure of 10 MPa. It was found the main products from glucose decomposition were 5-hydroxymethylf...The decomposition kinetics of glucose was studied in high-temperature liquid water （HTLW） from 180 to 220℃ under a pressure of 10 MPa. It was found the main products from glucose decomposition were 5-hydroxymethylfurfural （5-HMF） and levulinic acid （LA）. The decomposition kinetics of 5-HMF and stability of LA in HTLW were further investigated. A kinetic model for glucose decomposition was proposed accordingly. In the model, a series of first-order reactions with the consideration of parallel by-reactions were used to illustrate the decomposition of glucose. The decomposition activation energies of glucose, 5-HMF, and LA were evaluated as 118.85, 95.40, and 31.29 kJ·mol^-1, respectively.展开更多
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...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.展开更多
The catalytic performance of some quaternary ammonium salts for the liquid phase reaction of butanol and hydrochloric acid at different conditions was studied experimentally and compared with the traditional catalyst ...The catalytic performance of some quaternary ammonium salts for the liquid phase reaction of butanol and hydrochloric acid at different conditions was studied experimentally and compared with the traditional catalyst （ZnCl2）. The organic ammonium catalysts investigated include ionic liquids N-butyl-N-methyl imidazolium fluoborate （[BMIM][BF4]） and N-butyl-N-methylimidazolium chloride （[BMIM]Cl） as well as hydrochloric salts of N-methylimidazol （[HMIM]Cl）, pyridine （[HPy]Cl） and triethylamine （[HEt3N]Cl）. It is shown that the intrinsic catalytic performance of all organic ammonium salts except [HEt3N]Cl is slightly superior to ZnCl2, while the selectivity of butyl chloride is nearly at the same level around 96%. The conversion of butanol increases slightly with temperature and the catalyst amount added while the variation of selectivity is not obvious. Based on the recycle experiments, the ionic liquids as catalyst for the reaction of butanol and hydrochloric acid can be used more than 5 times, which suggests great potential of using ionic liquids as novel catalyst for such reactions.展开更多
Liquid phase oxidation of toluene is an environmental benign route for the production of benzoic acid.In a φ48mm bubble column reactor,the commercial process of toluene liquid phase oxidation was conducted with Co(CH...Liquid phase oxidation of toluene is an environmental benign route for the production of benzoic acid.In a φ48mm 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.展开更多
The complicated reaction mechanism and the character of competitive reactions lead to a stringent requirement for the catalyst of C_4 alkylation process. Due to their unique properties, ionic liquids(ILs) are thought ...The complicated reaction mechanism and the character of competitive reactions lead to a stringent requirement for the catalyst of C_4 alkylation process. Due to their unique properties, ionic liquids(ILs) are thought to be new potential acid catalysts for C_4 alkylation. An analysis of the regular and modified chloroaluminate ILs, novel Br?nsted ILs and composite ILs used in isobutane/butene alkylation shows that the use of either ILs or ILs coupled with mineral acid as homogeneous catalysts can help to greatly adjust the acid strength. By modifying the structural parameters of the cations and anions of the ILs, the solubility of the reactants could also be adjusted, which in turn displays a positive effect on improving the activity of ILs. Immobilization of ILs is an effective way to modulate the surface adsorption/desorption properties and acid strength distribution of the solid acid catalysts. Such a process has a tremendous potential to reduce the deactivation of catalyst and enhance the activity of the solid acid catalyst. The development of novel acid catalysts for C_4 alkylation is a comprehensive consideration of acid strength and its distribution, interfacial properties and transport characteristics.展开更多
Palladium(Pd)‐based catalysts are essential to drive high‐performance Suzuki coupling reactions,which are powerful tools for the synthesis of functional organic compounds.Herein,we developed a solution‐rapid‐annea...Palladium(Pd)‐based catalysts are essential to drive high‐performance Suzuki coupling reactions,which are powerful tools for the synthesis of functional organic compounds.Herein,we developed a solution‐rapid‐annealing process to stabilize nitrogen‐mesoporous carbon supported Pd single‐atom/cluster(Pd/NMC)material,which provided a catalyst with superior performance for Suzuki coupling reactions.In comparison with commercial palladium/carbon(Pd/C)catalysts,the Pd/NMC catalyst exhibited significantly boosted activity(100%selectivity and 95%yield)and excellent stability(almost no decay in activity after 10 reuse cycles)for the Suzuki coupling reactions of chlorobenzenes,together with superior yield and excellent selectivity in the fields of the board scope of the reactants.Moreover,our newly developed rapid annealing process of precursor solutions is applied as a generalized method to stabilize metal clusters(e.g.Pd,Pt,Ru),opening new possibilities in the construction of efficient highly dispersed metal atom and sub‐nanometer cluster catalysts with high performance.展开更多
In this paper, a kinetics model for the liquid-phase oxidation of 2-methyl-6-acetyl-naphthalene to 2,6-naphthalene dicarboxylic acid catalyzed by cobalt-manganese-bromide is proposed. The effects of the reaction tempe...In this paper, a kinetics model for the liquid-phase oxidation of 2-methyl-6-acetyl-naphthalene to 2,6-naphthalene dicarboxylic acid catalyzed by cobalt-manganese-bromide is proposed. The effects of the reaction temperature, catalyst concentration and ratio of catalyst on the lime evolution of the experimental concentration for the constituents including raw material, intermediates and product are investigated. The model parameters are determined in a nonlinear optimization, minimizing the difference between the simulated and experimental time evolution of the product composition obtained in a semi-batch oxidation reactor where the gas and liquid phase were well nuxed. The kinetics data demonstrate that the model is suitable to the liquid-phase oxidation of 2-methyl-6-acetyl-naphthalene to 2,6-naphthalene dicarboxylic acid.展开更多
Caffeic acid phenethyl ester(CAPE)is a rare,naturally occurring phenolic food additive.This work systematically reported fundamental data on conversion of caffeic acid(CA),yield of CAPE,and reactive selectivity during...Caffeic acid phenethyl ester(CAPE)is a rare,naturally occurring phenolic food additive.This work systematically reported fundamental data on conversion of caffeic acid(CA),yield of CAPE,and reactive selectivity during the lipase-catalyzed esterification process of CA and phenylethanol(PE)in ionic liquids(ILs).Sixteen ILs were selected as the reaction media,and the relative lipase-catalyzed synthesis properties of CAPE were measured in an effort to enhance the yield of CAPE with high selectivity.The results indicated that ILs containing weakly coordinating anions and cations with adequate alkyl chain length improved the synthesis of CAPE.[Emim][Tf2N]was selected as the optimal reaction media.The optimal parameters were as follows by response surface methodology(RSM):reaction temperature,84.0°C;mass ratio of Novozym 435 to CA,14︰1;and molar ratio of PE to CA,16︰1.The highest reactive selectivity of CAPE catalyzed by Novozym 435 in[Emim][Tf2N]reached 64.55%(CA conversion 98.76%and CAPE yield 63.75%,respectively).Thus,lipase-catalyzed esterification in ILs is a promising method suitable for CAPE production.展开更多
The acid-functionalized ionic liquid([HSO3Pmim]HSO4) was synthesized by a two-step method. Nuclear magnetic resonance(NMR) and Fourier transform infrared spectroscopy(FT-IR) show that the synthesis method is feasible ...The acid-functionalized ionic liquid([HSO3Pmim]HSO4) was synthesized by a two-step method. Nuclear magnetic resonance(NMR) and Fourier transform infrared spectroscopy(FT-IR) show that the synthesis method is feasible and high purity of ionic liquid can be obtained. Using [HSO3Pmim]HSO4as the catalyst, we studied the reaction kinetics of synthesizing sec-butyl alcohol from sec-butyl acetate and methanol by transesterification in a high-pressure batch reactor. The effects of temperature, initial molar ratio of methanol to ester, and catalyst concentration on the conversion of sec-butyl acetate were studied. Based on its possible reaction mechanism, a homogeneous kinetic model was established. The results show that the reaction heat ΔH is 10.94 × 103J·mol-1, so the reaction is an endothermic reaction. The activation energies Ea+and Ea-are 60.38 × 103 and 49.44 × 103J·mol-1,respectively.展开更多
According to the characteristics of FCC diesel, a technology of liquid-phase hydrodesulfurization of the diesel in tubular reactors was proposed and lab-scale experiments were carried out. A kinetic model for the hydr...According to the characteristics of FCC diesel, a technology of liquid-phase hydrodesulfurization of the diesel in tubular reactors was proposed and lab-scale experiments were carried out. A kinetic model for the hydrodesulfurization process was developed and verified. The model was utilized to predict the sulfur content of products under different operating conditions. The effects of temperature, space velocity, pressure, and hydrogen concentration on the dcsulfurization rate were investigated.展开更多
The computational fluid dynamics(CFD) code, FLUENT, was used to simulate the liquid-phase FCC diesel hydrotreating tubular reactor with a ceramic membrane tube dispenser. The chemical reaction and reaction heat were a...The computational fluid dynamics(CFD) code, FLUENT, was used to simulate the liquid-phase FCC diesel hydrotreating tubular reactor with a ceramic membrane tube dispenser. The chemical reaction and reaction heat were added to the model by user-defined function(UDF), showing the distribution of temperature and content of sulfides, nitrides, bicyclic aromatics and monocyclic aromatics in different parts of the reaction bed. When the pressure was 6.5 MPa, the amount of mixing hydrogen was 0.84%(m), the space velocity was 2 h-1 and the inlet temperature was 633 K, the temperature reached a maximum at a height of 0.15 m, and the range of radial temperature reached its maximum(2.5 K) at a height of 0.15 m. It indicated that the proper ratio of height to diameter of catalyst bed in the tubular reactor was 5-6. The increase of inlet temperature, the mixing hydrogen and the decrease of space velocity led to the decrease in the content of bicyclic aromatics, sulfides and nitrides, and the increase in monocyclic aromatics content, while the high temperature increased. The results were in good agreement with experimental data, indicating to the high accuracy of the model.展开更多
Hydroxyl radicals HO are generated under Fenton-like (Fe2++H2O2→HO?+OH?+Fe3+) catalytic conditions upon microwave irradiation. Liquid-phase direct catalytic oxidation of benzene to phenol was obtained using FeSO4 sup...Hydroxyl radicals HO are generated under Fenton-like (Fe2++H2O2→HO?+OH?+Fe3+) catalytic conditions upon microwave irradiation. Liquid-phase direct catalytic oxidation of benzene to phenol was obtained using FeSO4 supported on silica gel as a solid catalyst and hydrogen peroxide as the oxidant. The effects of various parameters, such as the different solvents, the amount of solvent used, the amount of catalyst used, the reaction time, the reaction temperature and the amount of hydrogen peroxide used on the yield of phenol were studied to identify optimum reaction conditions. Conventionally heated reaction gives a phenol yield of 0.6%. A higher phenol yield of 13.9% with a selectivity of 100% is obtained when the reaction mixture was irradiated with micro-wave energy. It is concluded that microwave irradiation offers more effective control of energy input for hydroxyl radical generation that is appropriate for various synthetic reactions.展开更多
To obtain new functional aromatic polymer materiul. 3,3＇-biacenaphthene, which is used as macromolecule intermediate of,funcrion aromatic polymer material, was synthesized through the coupling reaction of acenaphthen...To obtain new functional aromatic polymer materiul. 3,3＇-biacenaphthene, which is used as macromolecule intermediate of,funcrion aromatic polymer material, was synthesized through the coupling reaction of acenaphthene catalyzing by ionic liquid （[bmim]CI/FeCl3） at mild reaction condition. Pure 3,3＇-biacenaphthene was obtained hy recrystalling and column chromatography from the reaction mixture and was determined by GC/MS, SHNMR arid FTIR analysis. The influence of various reaction conditions on the yield of 3,3＇-biacenaphthene were studied by GC analysis. The result shows that the optimun synthesis conditions of the coupling reaction are, as following： the molar ratio of FeCl3 to [BmimlCl being 3, the mole ratio of FeCl3 in [Bmim]Cl/FeCl3 to acenaphthene being 4. the reaction temperamre being 20 ℃ the reaction time being 4h and the solvent of the reaction system being PhNO2 Under those conditions, the yield of the 3.3＇-biacenaphthene will be 48.71% and selectivity, of that will be 78.56 %. Farther more, [bmim]Cl/FeCl3 has no pollution to environments and can be reused.展开更多
Solid-aqueous interfaces and phenomena occurring at those interfaces are ubiquitously found in a plethora of chemical systems.When it comes to heterogeneous catalysis,however,our understanding of chemical transformati...Solid-aqueous interfaces and phenomena occurring at those interfaces are ubiquitously found in a plethora of chemical systems.When it comes to heterogeneous catalysis,however,our understanding of chemical transformations at solid-aqueous interfaces is relatively limited and primitive.This review phenomenologically describes a selection of water-engendered effects on the catalytic behavior for several prototypical acid-base-catalyzed reactions over solid catalysts,and critically assesses the general and special roles of water molecules,structural moieties derived from water,and ionic species that are dissolved in it,with an aim to extract novel concepts and principles that underpin heterogeneous acid-base catalysis in the aqueous phase.For alcohol dehydration catalyzed by solid Bronsted acids,rate inhibition by water is most typically related to the decrease in the acid strength and/or the preferential solvation of adsorbed species over the transition state as water molecules progressively solvate the acid site and form extended networks wherein protons are mobilized.Water also inhibits dehydration kinetics over most Lewis acid-base catalysts by competitive adsorption,but a few scattered reports reveal substantial rate enhancements due to the conversion of Lewis acid sites to Brønsted acid sites with higher catalytic activities upon the introduction of water.For aldol condensation on catalysts exposing Lewis acid-base pairs,the addition of water is generally observed to enhance the rate when C–C coupling is rate-limiting,but may result in rate inhibition by site-blocking when the initial unimolecular deprotonation is rate-limiting.Water can also promote aldol condensation on Brønsted acidic catalysts by facilitating inter-site communication between acid sites through hydrogen-bonding interactions.For metallozeolite-catalyzed sugar isomerization in aqueous media,the nucleation and networking of intrapore waters regulated by hydrophilic entities causes characteristic enthalpy-entropy tradeoffs as these water moieties interact with kinetically relevant hydride transfer transition states.The discussed examples collectively highlight the utmost importance of hydrogen-bonding interactions and ionization of covalently bonded surface moieties as the main factors underlying the uniqueness of water-mediated interfacial acid-base chemistries and the associated solvation effects in the aqueous phase or in the presence of water.A perspective is also provided for future research in this vibrant field.展开更多
基金Supported by the National Natural Science Foundation of China （20674068） and the Natural Science Foundation of Zhejiang Province （Y405157）.
文摘The decomposition kinetics of glucose was studied in high-temperature liquid water （HTLW） from 180 to 220℃ under a pressure of 10 MPa. It was found the main products from glucose decomposition were 5-hydroxymethylfurfural （5-HMF） and levulinic acid （LA）. The decomposition kinetics of 5-HMF and stability of LA in HTLW were further investigated. A kinetic model for glucose decomposition was proposed accordingly. In the model, a series of first-order reactions with the consideration of parallel by-reactions were used to illustrate the decomposition of glucose. The decomposition activation energies of glucose, 5-HMF, and LA were evaluated as 118.85, 95.40, and 31.29 kJ·mol^-1, respectively.
基金the Department of Science and Technology Management of PetroChina for providing financial support
文摘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.
基金Supported by the National Natural Science Foundation of China （No.20376004）
文摘The catalytic performance of some quaternary ammonium salts for the liquid phase reaction of butanol and hydrochloric acid at different conditions was studied experimentally and compared with the traditional catalyst （ZnCl2）. The organic ammonium catalysts investigated include ionic liquids N-butyl-N-methyl imidazolium fluoborate （[BMIM][BF4]） and N-butyl-N-methylimidazolium chloride （[BMIM]Cl） as well as hydrochloric salts of N-methylimidazol （[HMIM]Cl）, pyridine （[HPy]Cl） and triethylamine （[HEt3N]Cl）. It is shown that the intrinsic catalytic performance of all organic ammonium salts except [HEt3N]Cl is slightly superior to ZnCl2, while the selectivity of butyl chloride is nearly at the same level around 96%. The conversion of butanol increases slightly with temperature and the catalyst amount added while the variation of selectivity is not obvious. Based on the recycle experiments, the ionic liquids as catalyst for the reaction of butanol and hydrochloric acid can be used more than 5 times, which suggests great potential of using ionic liquids as novel catalyst for such reactions.
基金Supported by the National Natural Science Foundation of China （20576081, 20736009） and the Ph.D. Programs Foundation of Ministry of Education of China （20070610128）.
文摘Liquid phase oxidation of toluene is an environmental benign route for the production of benzoic acid.In a φ48mm 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.
基金Supported by the National Natural Science Foundation of China(21276163,21576168)
文摘The complicated reaction mechanism and the character of competitive reactions lead to a stringent requirement for the catalyst of C_4 alkylation process. Due to their unique properties, ionic liquids(ILs) are thought to be new potential acid catalysts for C_4 alkylation. An analysis of the regular and modified chloroaluminate ILs, novel Br?nsted ILs and composite ILs used in isobutane/butene alkylation shows that the use of either ILs or ILs coupled with mineral acid as homogeneous catalysts can help to greatly adjust the acid strength. By modifying the structural parameters of the cations and anions of the ILs, the solubility of the reactants could also be adjusted, which in turn displays a positive effect on improving the activity of ILs. Immobilization of ILs is an effective way to modulate the surface adsorption/desorption properties and acid strength distribution of the solid acid catalysts. Such a process has a tremendous potential to reduce the deactivation of catalyst and enhance the activity of the solid acid catalyst. The development of novel acid catalysts for C_4 alkylation is a comprehensive consideration of acid strength and its distribution, interfacial properties and transport characteristics.
文摘Palladium(Pd)‐based catalysts are essential to drive high‐performance Suzuki coupling reactions,which are powerful tools for the synthesis of functional organic compounds.Herein,we developed a solution‐rapid‐annealing process to stabilize nitrogen‐mesoporous carbon supported Pd single‐atom/cluster(Pd/NMC)material,which provided a catalyst with superior performance for Suzuki coupling reactions.In comparison with commercial palladium/carbon(Pd/C)catalysts,the Pd/NMC catalyst exhibited significantly boosted activity(100%selectivity and 95%yield)and excellent stability(almost no decay in activity after 10 reuse cycles)for the Suzuki coupling reactions of chlorobenzenes,together with superior yield and excellent selectivity in the fields of the board scope of the reactants.Moreover,our newly developed rapid annealing process of precursor solutions is applied as a generalized method to stabilize metal clusters(e.g.Pd,Pt,Ru),opening new possibilities in the construction of efficient highly dispersed metal atom and sub‐nanometer cluster catalysts with high performance.
文摘In this paper, a kinetics model for the liquid-phase oxidation of 2-methyl-6-acetyl-naphthalene to 2,6-naphthalene dicarboxylic acid catalyzed by cobalt-manganese-bromide is proposed. The effects of the reaction temperature, catalyst concentration and ratio of catalyst on the lime evolution of the experimental concentration for the constituents including raw material, intermediates and product are investigated. The model parameters are determined in a nonlinear optimization, minimizing the difference between the simulated and experimental time evolution of the product composition obtained in a semi-batch oxidation reactor where the gas and liquid phase were well nuxed. The kinetics data demonstrate that the model is suitable to the liquid-phase oxidation of 2-methyl-6-acetyl-naphthalene to 2,6-naphthalene dicarboxylic acid.
基金Supported by the Natural Science Foundation of Jiangsu Province（BK2009213） China Postdoctoral Science Foundation funded Project（2012M510124）+2 种基金 Qing Lan Project of Jiangsu Province,National Natural Science Foundation of China（21206061） Research Project of Jiangsu University of Science and Technology（35211002） Modern Agro-industry Technology Research System of China（CARS-22）
文摘Caffeic acid phenethyl ester(CAPE)is a rare,naturally occurring phenolic food additive.This work systematically reported fundamental data on conversion of caffeic acid(CA),yield of CAPE,and reactive selectivity during the lipase-catalyzed esterification process of CA and phenylethanol(PE)in ionic liquids(ILs).Sixteen ILs were selected as the reaction media,and the relative lipase-catalyzed synthesis properties of CAPE were measured in an effort to enhance the yield of CAPE with high selectivity.The results indicated that ILs containing weakly coordinating anions and cations with adequate alkyl chain length improved the synthesis of CAPE.[Emim][Tf2N]was selected as the optimal reaction media.The optimal parameters were as follows by response surface methodology(RSM):reaction temperature,84.0°C;mass ratio of Novozym 435 to CA,14︰1;and molar ratio of PE to CA,16︰1.The highest reactive selectivity of CAPE catalyzed by Novozym 435 in[Emim][Tf2N]reached 64.55%(CA conversion 98.76%and CAPE yield 63.75%,respectively).Thus,lipase-catalyzed esterification in ILs is a promising method suitable for CAPE production.
基金Supported by the New Century Excellent Talents in Fujian Province(JA12014)the Natural Science Foundation for Distinguished Young Scholars of Fujian(2014J06004)
文摘The acid-functionalized ionic liquid([HSO3Pmim]HSO4) was synthesized by a two-step method. Nuclear magnetic resonance(NMR) and Fourier transform infrared spectroscopy(FT-IR) show that the synthesis method is feasible and high purity of ionic liquid can be obtained. Using [HSO3Pmim]HSO4as the catalyst, we studied the reaction kinetics of synthesizing sec-butyl alcohol from sec-butyl acetate and methanol by transesterification in a high-pressure batch reactor. The effects of temperature, initial molar ratio of methanol to ester, and catalyst concentration on the conversion of sec-butyl acetate were studied. Based on its possible reaction mechanism, a homogeneous kinetic model was established. The results show that the reaction heat ΔH is 10.94 × 103J·mol-1, so the reaction is an endothermic reaction. The activation energies Ea+and Ea-are 60.38 × 103 and 49.44 × 103J·mol-1,respectively.
基金the financial support from the SINOPEC(No.2014310031600599)
文摘According to the characteristics of FCC diesel, a technology of liquid-phase hydrodesulfurization of the diesel in tubular reactors was proposed and lab-scale experiments were carried out. A kinetic model for the hydrodesulfurization process was developed and verified. The model was utilized to predict the sulfur content of products under different operating conditions. The effects of temperature, space velocity, pressure, and hydrogen concentration on the dcsulfurization rate were investigated.
文摘The computational fluid dynamics(CFD) code, FLUENT, was used to simulate the liquid-phase FCC diesel hydrotreating tubular reactor with a ceramic membrane tube dispenser. The chemical reaction and reaction heat were added to the model by user-defined function(UDF), showing the distribution of temperature and content of sulfides, nitrides, bicyclic aromatics and monocyclic aromatics in different parts of the reaction bed. When the pressure was 6.5 MPa, the amount of mixing hydrogen was 0.84%(m), the space velocity was 2 h-1 and the inlet temperature was 633 K, the temperature reached a maximum at a height of 0.15 m, and the range of radial temperature reached its maximum(2.5 K) at a height of 0.15 m. It indicated that the proper ratio of height to diameter of catalyst bed in the tubular reactor was 5-6. The increase of inlet temperature, the mixing hydrogen and the decrease of space velocity led to the decrease in the content of bicyclic aromatics, sulfides and nitrides, and the increase in monocyclic aromatics content, while the high temperature increased. The results were in good agreement with experimental data, indicating to the high accuracy of the model.
基金supported by the National Natural Science Foundation of China (No.50921002)
文摘Hydroxyl radicals HO are generated under Fenton-like (Fe2++H2O2→HO?+OH?+Fe3+) catalytic conditions upon microwave irradiation. Liquid-phase direct catalytic oxidation of benzene to phenol was obtained using FeSO4 supported on silica gel as a solid catalyst and hydrogen peroxide as the oxidant. The effects of various parameters, such as the different solvents, the amount of solvent used, the amount of catalyst used, the reaction time, the reaction temperature and the amount of hydrogen peroxide used on the yield of phenol were studied to identify optimum reaction conditions. Conventionally heated reaction gives a phenol yield of 0.6%. A higher phenol yield of 13.9% with a selectivity of 100% is obtained when the reaction mixture was irradiated with micro-wave energy. It is concluded that microwave irradiation offers more effective control of energy input for hydroxyl radical generation that is appropriate for various synthetic reactions.
基金National Natural Science Foundation of China (No. 20207003)
文摘To obtain new functional aromatic polymer materiul. 3,3＇-biacenaphthene, which is used as macromolecule intermediate of,funcrion aromatic polymer material, was synthesized through the coupling reaction of acenaphthene catalyzing by ionic liquid （[bmim]CI/FeCl3） at mild reaction condition. Pure 3,3＇-biacenaphthene was obtained hy recrystalling and column chromatography from the reaction mixture and was determined by GC/MS, SHNMR arid FTIR analysis. The influence of various reaction conditions on the yield of 3,3＇-biacenaphthene were studied by GC analysis. The result shows that the optimun synthesis conditions of the coupling reaction are, as following： the molar ratio of FeCl3 to [BmimlCl being 3, the mole ratio of FeCl3 in [Bmim]Cl/FeCl3 to acenaphthene being 4. the reaction temperamre being 20 ℃ the reaction time being 4h and the solvent of the reaction system being PhNO2 Under those conditions, the yield of the 3.3＇-biacenaphthene will be 48.71% and selectivity, of that will be 78.56 %. Farther more, [bmim]Cl/FeCl3 has no pollution to environments and can be reused.
文摘Solid-aqueous interfaces and phenomena occurring at those interfaces are ubiquitously found in a plethora of chemical systems.When it comes to heterogeneous catalysis,however,our understanding of chemical transformations at solid-aqueous interfaces is relatively limited and primitive.This review phenomenologically describes a selection of water-engendered effects on the catalytic behavior for several prototypical acid-base-catalyzed reactions over solid catalysts,and critically assesses the general and special roles of water molecules,structural moieties derived from water,and ionic species that are dissolved in it,with an aim to extract novel concepts and principles that underpin heterogeneous acid-base catalysis in the aqueous phase.For alcohol dehydration catalyzed by solid Bronsted acids,rate inhibition by water is most typically related to the decrease in the acid strength and/or the preferential solvation of adsorbed species over the transition state as water molecules progressively solvate the acid site and form extended networks wherein protons are mobilized.Water also inhibits dehydration kinetics over most Lewis acid-base catalysts by competitive adsorption,but a few scattered reports reveal substantial rate enhancements due to the conversion of Lewis acid sites to Brønsted acid sites with higher catalytic activities upon the introduction of water.For aldol condensation on catalysts exposing Lewis acid-base pairs,the addition of water is generally observed to enhance the rate when C–C coupling is rate-limiting,but may result in rate inhibition by site-blocking when the initial unimolecular deprotonation is rate-limiting.Water can also promote aldol condensation on Brønsted acidic catalysts by facilitating inter-site communication between acid sites through hydrogen-bonding interactions.For metallozeolite-catalyzed sugar isomerization in aqueous media,the nucleation and networking of intrapore waters regulated by hydrophilic entities causes characteristic enthalpy-entropy tradeoffs as these water moieties interact with kinetically relevant hydride transfer transition states.The discussed examples collectively highlight the utmost importance of hydrogen-bonding interactions and ionization of covalently bonded surface moieties as the main factors underlying the uniqueness of water-mediated interfacial acid-base chemistries and the associated solvation effects in the aqueous phase or in the presence of water.A perspective is also provided for future research in this vibrant field.
