Deformable catalytic material with excellent flexible structure is a new type of catalyst that has been applied in various chemical reactions,especially electrocatalytic hydrogen evolution reaction(HER).In recent year...Deformable catalytic material with excellent flexible structure is a new type of catalyst that has been applied in various chemical reactions,especially electrocatalytic hydrogen evolution reaction(HER).In recent years,deformable catalysts for HER have made great progress and would become a research hotspot.The catalytic activities of deformable catalysts could be adjustable by the strain engineering and surface reconfiguration.The surface curvature of flexible catalytic materials is closely related to the electrocatalytic HER properties.Here,firstly,we systematically summarized self-adaptive catalytic performance of deformable catalysts and various micro–nanostructures evolution in catalytic HER process.Secondly,a series of strategies to design highly active catalysts based on the mechanical flexibility of lowdimensional nanomaterials were summarized.Last but not least,we presented the challenges and prospects of the study of flexible and deformable micro–nanostructures of electrocatalysts,which would further deepen the understanding of catalytic mechanisms of deformable HER catalyst.展开更多
As one of the few renewable aromatic resources,the research of depolymerization of lignin into highvalue chemicals has attracted extensive attention in recent years.Catalytic wet aerobic oxidation(CWAO)is an effective...As one of the few renewable aromatic resources,the research of depolymerization of lignin into highvalue chemicals has attracted extensive attention in recent years.Catalytic wet aerobic oxidation(CWAO)is an effective technology to convert lignin like sodium lignosulfonate(SL),a lignin derivative,into aromatic aldehydes such as vanillin and syringaldehyde.However,how to improve the yield of aromatic aldehyde and conversion efficiency is still a challenge,and many operating conditions that significantly affect the yield of these aromatic compounds have rarely been investigated systematically.In this work,we adopted the stirred tank reactor(STR)for the CWAO process with nano-CuO as catalyst to achieve the conversion of SL into vanillin and syringaldehyde.The effect of operating conditions including reaction time,oxygen partial pressure,reaction temperature,SL concentration,rotational speed,catalyst amount,and NaOH concentration on the yield of single phenolic compound was systematically investigated.The results revealed that all these operating conditions exhibit a significant effect on the aromatic aldehyde yield.Therefore,they should be regulated in an optimal value to obtain high yield of these aldehydes.More importantly,the reaction kinetics of the lignin oxidation was explored.This work could provide basic data for the optimization and design of industrial operation of lignin oxidation.展开更多
The integrated catalytic hydrogenation and catalytic cracking process has been gradually adopted by refineries to satisfy the requirements for manufacture of light and clean petroleum products. To explore the reaction...The integrated catalytic hydrogenation and catalytic cracking process has been gradually adopted by refineries to satisfy the requirements for manufacture of light and clean petroleum products. To explore the reaction laws of hydrogenated aromatics in hydrotreated oil, the catalytic cracking reaction laws of hydrogenated aromatics have been reviewed by taking tetralin and decalin as examples of different degrees of hydrogenated aromatics. Moreover, the reaction mechanism of tetralin and decalin has been analyzed emphatically. The effects of zeolite pore structure, acid properties and process parameters on reaction laws have been analyzed carefully. It is considered that the catalytic cracking performance of hydrogenated aromatics with different hydrogen saturation degrees is quite different. It is necessary to control the hydrogenation depth, optimize the hydrocarbon composition of catalytic cracking feed materials for maximizing the yield of target products.展开更多
To develop more efficient chemical methods for the demineralization of organic pollutants from water bodies, which one was also mimic to the nature, a degradation of methylene blue by Fe(Ⅲ) and H 2O 2 in the absenc...To develop more efficient chemical methods for the demineralization of organic pollutants from water bodies, which one was also mimic to the nature, a degradation of methylene blue by Fe(Ⅲ) and H 2O 2 in the absence of light instead of Fe(Ⅱ) and H 2O 2 was studied. Results showed that use of Fe (Ⅲ) is more promising than Fe(Ⅱ). The present study reflects that Fenton reaction is more efficient, in the presence of a small amount of salicylic acid is added which is a one of the priority pollutant.展开更多
Herein, Co_3O_4 nanoparticles/nitrogen-doped carbon(Co_3O_4/NPC) composites with different structures were prepared via a facile method. Structure control was achieved by the rational morphology design of ZIF-67 precu...Herein, Co_3O_4 nanoparticles/nitrogen-doped carbon(Co_3O_4/NPC) composites with different structures were prepared via a facile method. Structure control was achieved by the rational morphology design of ZIF-67 precursors, which were then pyrolyzed in air to obtain Co_3O_4/NPC composites. When applied as catalysts for the oxygen evolution reaction(OER), the M-Co_3O_4/NPC composites derived from the flower-like ZIF-67 showedsuperior catalytic activities than those derived from the rhombic dodecahedron and hollow spherical ZIF-67. The former M-Co_3O_4/NPC composite displayed a small overpotential of 0.3 V, low onset potential of 1.41 V, small Tafel slope of 83 m V dec^(-1), and a desirable stability.(94.7% OER activity was retained after 10 h.) The excellent performance of the flower-like M-Co_3O_4/NPC composite in the OER was attributed to its favorable structure.展开更多
Thermal and photothermal catalytic selec-tive oxidation of isobutane to methacrylic acid(MAA)are comparatively studied over a keggin-type Cs2.9Cu0.34V0.49PMo12O40 het-eropolyacid acid.An introduction of light was obse...Thermal and photothermal catalytic selec-tive oxidation of isobutane to methacrylic acid(MAA)are comparatively studied over a keggin-type Cs2.9Cu0.34V0.49PMo12O40 het-eropolyacid acid.An introduction of light was observed to enhance both the i-C4H10 conversion and the MAA selectivity,and consequently the MAA formate rate,particularly at low temperatures.Characterization re-sults show that oxidation of methacrolein(MAL)to MAA is the rate-limiting step while UV light illumination promotes the oxidation ofσ-bonded MAL with OH groups toσ-bonded MAA on the catalyst surface.These results demonstrate a synergistic effect of thermal cataly-sis and photocatalysis in selective oxidation of isobutane to MAA,which suggests photother-mal catalysis as a promising strategy to catalyze the selective oxidation of higher hydrocar-bons at relative mild reaction conditions.展开更多
The catalytic packing is the core component of the catalytic distillation,and how the catalyst exists in the packing has significant influence on the process.To investigate the effect of catalyst packings on the catal...The catalytic packing is the core component of the catalytic distillation,and how the catalyst exists in the packing has significant influence on the process.To investigate the effect of catalyst packings on the catalytic distillation process,the classical ethyl acetate reactive distillation system was utilized,and a supported catalytic packing(SCP)was prepared in comparison with the conventional tea-bag catalytic packing(TBP).Laboratory scale experiments showed that the ethyl acetate conversion of the SCP was superior to the TBP at a low catalyst loading.The effects of reaction kinetics,mass transfer performance and actual catalytic efficiency of the packings on this process were regarded as reasons and studied by combining the experiments and numerical simulation.Results suggested that the relatively immediate“in-situ separation”caused by the rapid reaction kinetics and better mass transfer performance of SCP may be a main reason for the difference of the conversion.展开更多
To produce low olefin gasoline with high octane number by Fischer-Tropsch (F-T) wax fluid catalytic cracking (FCC) process, operating conditions optimization were carried out in the pilot-scale riser and turbulent flu...To produce low olefin gasoline with high octane number by Fischer-Tropsch (F-T) wax fluid catalytic cracking (FCC) process, operating conditions optimization were carried out in the pilot-scale riser and turbulent fluidized bed (TFB) FCC unit. The experimental results in the riser indicated that under the condition of low reaction temperature and regenerated catalyst temperature, large catalyst-to-oil weight ratio (C/O) and long reaction time, the gasoline olefin content could be reduced to 20.28 wt%, but there is large octane number loss owing to a great loss in high octane number olefin. Therefore, a novel FCC process using the TFB reactor was proposed to strengthen the aromatization reaction. The reaction performance of TFB reactor were investigated. The result demonstrated that the TFB reactor has more significant effect in reducing olefins and improving aromatics. At the expense of certain gasoline yield, the gasoline olefin content reduced to 23.70 wt%, aromatics content could increase to 26.79 wt% and the RON was up to 91.0. The comparison of reactor structure and fluidization demonstrated that the TFB reactor has higher catalyst bed density. The reaction heat and coke combustion heat was calculated indicating the feasibility of its industrial application of the TFB process.展开更多
Transfer hydrogenation(TH) with in situ generated hydrogen donor is of great importance in reduction reactions, and an alternative strategy to traditional hydrogenation processes involving pressurized molecular hydrog...Transfer hydrogenation(TH) with in situ generated hydrogen donor is of great importance in reduction reactions, and an alternative strategy to traditional hydrogenation processes involving pressurized molecular hydrogen. Ammonia borane(NH3BH3, AB) is a promising material of hydrogen storage, and it has attracted much attention in reductive organic transformations owing to its high activity, good atom economy, nontoxicity, sustainability, and ease of transport and storage. This review focuses on summarizing the recent progress of AB-mediated TH reactions of diverse substrates including nitro compounds, nitriles, imines, alkenes, alkynes, carbonyl compounds(ketones and aldehydes), carbon dioxide,and N-and O-heterocycles. Syntheses protocols(metal-containing and metal-free), the effect of reaction parameters, product distribution, and variation of reactivity are surveyed, and the mechanism of each reaction involving the action mode of AB as well as structure-activity relationships is discussed in detail. Finally, perspectives are presented to highlight the challenges and opportunities for AB-enabled TH reactions of unsaturated compounds.展开更多
Ni and carbon materials exhibit remarkable catalysis for the hydriding reaction of Mg.But the underlying mechanism of Ni/C hybrid catalysis is still unclear.In this work,density functional theory(DFT)calculation is ap...Ni and carbon materials exhibit remarkable catalysis for the hydriding reaction of Mg.But the underlying mechanism of Ni/C hybrid catalysis is still unclear.In this work,density functional theory(DFT)calculation is applied to investigate the effect of Ni/C co-incorporation on the hydriding reaction of Mg crystal.The morphology and crystal structure of the Ni/C co-incorporated Mg sample show that the coincorporated structure is credible.The transition state searching calculation suggests that both the incorporations of Ni and C are beneficial for the H_(2) dissociation.But Ni atom has a dramatic improvement for H_(2) dissociation and makes the H diffusion become limiting step of the hyriding reaction.The Ni dz_(2)orbit and H s orbit accept the electrons and combine together compactly,while the Ni d_(xy) orbit is half-occupied.The catalytic effect of Ni on H_(2) dissociation can be ascribed to the bridging effect of Ni d_(xy) orbit.The incorporation of C can weaken the over-strong interaction between Ni and H which hindered the H diffusion on Mg(0001).The Ni/C co-incorporated Mg(0001)shows the best performance during hyriding reaction compared with the clean and single incorporated Mg(0001).展开更多
Catalytic co-cracking of Fischer–Tropsch(FT) light distillate and methanol combines highly endothermic olefin cracking reaction with exothermic methanol conversion over ZSM-5 catalyst to produce light olefins through...Catalytic co-cracking of Fischer–Tropsch(FT) light distillate and methanol combines highly endothermic olefin cracking reaction with exothermic methanol conversion over ZSM-5 catalyst to produce light olefins through a nearly thermoneutral process. The kinetic behavior of co-cracking reactions was investigated by different feed conditions: methanol feed only, olefin feed only and co-feed of methanol with olefins or F–T distillate. The results showed that methanol converted to C2–C6 olefins in first-order parallel reaction at low space time, methylation and oligomerization–cracking prevailed for the co-feed of methanol and C2–C5 olefins, while for C6–C8 olefins,monomolecular cracking was the dominant reaction whether fed alone or co-fed with methanol. For FT distillate and methanol co-feed, alkanes were almost un-reactive, C3–C5 olefins were obtained as main products, accounting for 71 wt% for all products. A comprehensive co-cracking reaction scheme was proposed and the model parameters were estimated by the nonlinear least square method. It was verified by experimental data that the kinetic model was reliable to predict major product distribution for co-cracking of FT distillate with methanol and could be used for further reactor development and process design.展开更多
In this study a mathematical model of a small scale single pellet for the oxidative coupling of methane(OCM)over titanite pervoskite is developed.The method is based on a computational fluid dynamics(CFD)code whic...In this study a mathematical model of a small scale single pellet for the oxidative coupling of methane(OCM)over titanite pervoskite is developed.The method is based on a computational fluid dynamics(CFD)code which known as Fluent may be adopted to model the reactions that take place inside the porous catalyst pellet.The steady state single pellet model is coupled with a kinetic model and the intra-pellet concentration profiles of species are provided.Subsequent to achieving this goal,a nonlinear reaction network consisting of nine catalytic reactions and one gas phase reaction as an external program is successfully implemented to CFD-code as a reaction term in solving the equations.This study is based on the experimental design which is conducted in a differential reactor with a Sn/BaTiO3 catalyst(7-8 mesh) at atmospheric pressure,GHSV of 12000 h-1,ratio of methane to oxygen of 2,and three different temperatures of 1023,1048 and 1073 K.The modeling results such as selectivity and conversion at the pellet exit are in good agreement with the experimental data.Therefore,it is suggested that to achieve high yield in OCM process the modeling of the single pellet should be considered as the heart of catalytic fixed bed reactor.展开更多
Ce0.5Zr0.5O2 solid solution was successfully synthesized using cerium nitrate, zirconium nitrate, and urea as raw materials by the microwave irradiation method and characterized by X-ray diffraction, fluorescence spec...Ce0.5Zr0.5O2 solid solution was successfully synthesized using cerium nitrate, zirconium nitrate, and urea as raw materials by the microwave irradiation method and characterized by X-ray diffraction, fluorescence spectrum, transmission electron microscopy, and infrared spectrum. Its acid catalytic activity was evaluated in the esterification reaction of acetic acid and n-butyl alcohol. The results show that Ce0.5Zr0.5O2 solid solution has cubic fluorite structure, and its particle diameter is in the nanometer scale. As a sort of solid acid, it possesses a higher acid catalytic activity and can be easily separated from reaction liquids. It can be used for several times, and basically, its activity keeps constant. The proton acid sites and Lewis acid sites exist in the structure of Ce0.5Zr0.5O2 solid solution.展开更多
Pd/LaxPbyMnOz, Pd/C, Pd/molecular sieve and Pd-heteropoly acid catalysts for direct synthesis of diphenyl carbonate (DPC) by heterogeneous catalytic reaction were compared and the results of DPC synthesis indicated th...Pd/LaxPbyMnOz, Pd/C, Pd/molecular sieve and Pd-heteropoly acid catalysts for direct synthesis of diphenyl carbonate (DPC) by heterogeneous catalytic reaction were compared and the results of DPC synthesis indicated that the catalyst Pd/LaxPbyMnOz had higher activity. The Pd/LaxPbyMnOz catalyst and the support was characterized by XRD, SEM and TEM, the main phase was La0.62Pb0.38MnO3 and the average diameter could be about 25.4 nm. The optimum conditions for synthesis of DPC with Pd/LaxPbyMnOz were determined by orthogonal experiments and the experimental results showed that reaction temperature was the first factor of effect on the selectivity and yield of DPC, and the concentration of O2 in gas phase also had significant effect on selectivity of DPC. The optimum reaction conditions were catMyst/phenol mass ratio 1 to 50, pressure 4.5 MPa,volume concentration of O2 25%, reaction temperature 60° and reaction time 4 h. The maximum yield and average selectivity could reach 13% and 97% respectively in the batch operation.展开更多
Approximate analytical expressions of overall effectiveness factors for parallel catalytic reac-tions occurring in a spherical catalyst pellet with both internal and external mass transfer resistancesare obtained afte...Approximate analytical expressions of overall effectiveness factors for parallel catalytic reac-tions occurring in a spherical catalyst pellet with both internal and external mass transfer resistancesare obtained after taking the information given by asymptotic solutions valid for small and largevalues of Thiele moduli.This approximate procedure is feasible for power law as well asLangmuir-Hinshelwood kinetics and the agreement between the approximation and the numerical re-sults is good enough for practical purposes.Moreover,the method does not require any iterative ortrial-and-error computation,and can be conveniently applied in most practical calculations for reac-tors giving reliable results.展开更多
The efficient production of hydrogen through electrocatalytic decomposition of water has broad prospects in modern energy equipment.However,the catalytic efficiency and durability of hydrogen evolution catalyst are st...The efficient production of hydrogen through electrocatalytic decomposition of water has broad prospects in modern energy equipment.However,the catalytic efficiency and durability of hydrogen evolution catalyst are still very deficient,which need to be further explored.Here in this work,we prove that introducing a graphene layer(Gr)between the molybdenum disulfide and nickel foam(Ni-F)substrate can greatly improve the catalytic performance of the hybrid.Owing to the excitation of local surface plasmon resonance(LSPR)of gold nanoparticles(NPs),the electrocatalytic hydrogen releasing activity of the MoS_(2)/Gr/Ni-F heterostructure is greatly improved.This results in a significant increase in the current density of AuNPs/MoS_(2)/Gr/Ni-F composite material under light irradiation and in the dark at 0.2 V(versus reversible hydrogen electrode(RHE)),which is much better than in MoS_(2)/Gr/Ni-F composite materials.The enhancement of hydrogen release can be attributed to the injection of hot electrons into MoS_(2)/Gr/Ni-F by AuNPs,which will improve the electron density of MoS_(2)/Gr/Ni-F,promote the reduction of H_(2)O,and further reduce the activation energy of the electrocatalyst hydrogen evolution reaction(HER).We also prove that the introduction of graphene can improve its stability in acidic catalytic environments.This work provides a new way of designing efficient water splitting system.展开更多
The catalytic efficiency of modified nanodiamonds (MND) in reactions of interaction between organic compounds was demonstrated on the example of azocoupling reaction (hydrogen peroxide-4-aminoantipyrine-phenol). It wa...The catalytic efficiency of modified nanodiamonds (MND) in reactions of interaction between organic compounds was demonstrated on the example of azocoupling reaction (hydrogen peroxide-4-aminoantipyrine-phenol). It was found that catalytic action of MND was caused by redox active metal ions of Fe and Cu located on the MND surface. The neutralization of the ions significantly decreased catalytic properties of MND.展开更多
A series of lanthanide sulfates coordination complexes, Ln2(SO4)3(H2O)8 (Ln = Pr (1), Nd (2), Tb (3), Sm (4), Dy (5), Gd (7), Ho (8)), and EuK(SO4)2 (6), were constructed by the reaction in situ of lanthanide ions (Ln...A series of lanthanide sulfates coordination complexes, Ln2(SO4)3(H2O)8 (Ln = Pr (1), Nd (2), Tb (3), Sm (4), Dy (5), Gd (7), Ho (8)), and EuK(SO4)2 (6), were constructed by the reaction in situ of lanthanide ions (Ln3+) with flexible dodecanedioic acid and rigid aromatic 5-sulfosalicylic acid under hydrothermal conditions. All of them were characterized by elemental analysis, IR spectroscopy, and single-crystal X-ray diffraction. The crystal structures and coordination modes of metal centers and sulfate ions, as well as the novel reaction mechanism and different conditions of lanthanide ions and 5-sulfosalicylic acid to form the series of lanthanide sulfate complexes, were discussed in detail. Solid-state properties for these crystalline materials, such as thermal stability and powder X-ray diffraction have been investigated. Additionally, the photoluminescent characterizations of the complexes 3, 4, 5 and 6, and the catalytic properties of all the complexes about cyclohexane being oxidized into cyclohexanone/cyclohexanol were investigated and compared.展开更多
A new type of macro-micro-macro triple electrode is fabricated. The kinetic equation is obtained by using the decrease in collection current to determine the kinetic constant of homogeneous catalytic reaction, the met...A new type of macro-micro-macro triple electrode is fabricated. The kinetic equation is obtained by using the decrease in collection current to determine the kinetic constant of homogeneous catalytic reaction, the method can be used to study homogeneous chemical reaction with any magnitude of kinetic constant, and overcomes the disadvantages that the microelectrode is only suitable for fast catalytic reaction.展开更多
基金This work was financially supported by the National Natural Science Foundation of China(Nos.51902101 and 21875203)the Natural Science Foundation of Hunan Province(Nos.2021JJ40044 and 2023JJ50287)Natural Science Foundation of Jiangsu Province(No.BK20201381).
文摘Deformable catalytic material with excellent flexible structure is a new type of catalyst that has been applied in various chemical reactions,especially electrocatalytic hydrogen evolution reaction(HER).In recent years,deformable catalysts for HER have made great progress and would become a research hotspot.The catalytic activities of deformable catalysts could be adjustable by the strain engineering and surface reconfiguration.The surface curvature of flexible catalytic materials is closely related to the electrocatalytic HER properties.Here,firstly,we systematically summarized self-adaptive catalytic performance of deformable catalysts and various micro–nanostructures evolution in catalytic HER process.Secondly,a series of strategies to design highly active catalysts based on the mechanical flexibility of lowdimensional nanomaterials were summarized.Last but not least,we presented the challenges and prospects of the study of flexible and deformable micro–nanostructures of electrocatalysts,which would further deepen the understanding of catalytic mechanisms of deformable HER catalyst.
基金supported by the National Key Research and Development Program of China(2019YFA0210302)the National Natural Science Foundation of China(21878009).
文摘As one of the few renewable aromatic resources,the research of depolymerization of lignin into highvalue chemicals has attracted extensive attention in recent years.Catalytic wet aerobic oxidation(CWAO)is an effective technology to convert lignin like sodium lignosulfonate(SL),a lignin derivative,into aromatic aldehydes such as vanillin and syringaldehyde.However,how to improve the yield of aromatic aldehyde and conversion efficiency is still a challenge,and many operating conditions that significantly affect the yield of these aromatic compounds have rarely been investigated systematically.In this work,we adopted the stirred tank reactor(STR)for the CWAO process with nano-CuO as catalyst to achieve the conversion of SL into vanillin and syringaldehyde.The effect of operating conditions including reaction time,oxygen partial pressure,reaction temperature,SL concentration,rotational speed,catalyst amount,and NaOH concentration on the yield of single phenolic compound was systematically investigated.The results revealed that all these operating conditions exhibit a significant effect on the aromatic aldehyde yield.Therefore,they should be regulated in an optimal value to obtain high yield of these aldehydes.More importantly,the reaction kinetics of the lignin oxidation was explored.This work could provide basic data for the optimization and design of industrial operation of lignin oxidation.
文摘The integrated catalytic hydrogenation and catalytic cracking process has been gradually adopted by refineries to satisfy the requirements for manufacture of light and clean petroleum products. To explore the reaction laws of hydrogenated aromatics in hydrotreated oil, the catalytic cracking reaction laws of hydrogenated aromatics have been reviewed by taking tetralin and decalin as examples of different degrees of hydrogenated aromatics. Moreover, the reaction mechanism of tetralin and decalin has been analyzed emphatically. The effects of zeolite pore structure, acid properties and process parameters on reaction laws have been analyzed carefully. It is considered that the catalytic cracking performance of hydrogenated aromatics with different hydrogen saturation degrees is quite different. It is necessary to control the hydrogenation depth, optimize the hydrocarbon composition of catalytic cracking feed materials for maximizing the yield of target products.
文摘To develop more efficient chemical methods for the demineralization of organic pollutants from water bodies, which one was also mimic to the nature, a degradation of methylene blue by Fe(Ⅲ) and H 2O 2 in the absence of light instead of Fe(Ⅱ) and H 2O 2 was studied. Results showed that use of Fe (Ⅲ) is more promising than Fe(Ⅱ). The present study reflects that Fenton reaction is more efficient, in the presence of a small amount of salicylic acid is added which is a one of the priority pollutant.
基金supported by the Scientific and Technological Innovation Platform of Fujian Province(2006L2003)Scientific Research Project of Wuyi University(YJ201706)
文摘Herein, Co_3O_4 nanoparticles/nitrogen-doped carbon(Co_3O_4/NPC) composites with different structures were prepared via a facile method. Structure control was achieved by the rational morphology design of ZIF-67 precursors, which were then pyrolyzed in air to obtain Co_3O_4/NPC composites. When applied as catalysts for the oxygen evolution reaction(OER), the M-Co_3O_4/NPC composites derived from the flower-like ZIF-67 showedsuperior catalytic activities than those derived from the rhombic dodecahedron and hollow spherical ZIF-67. The former M-Co_3O_4/NPC composite displayed a small overpotential of 0.3 V, low onset potential of 1.41 V, small Tafel slope of 83 m V dec^(-1), and a desirable stability.(94.7% OER activity was retained after 10 h.) The excellent performance of the flower-like M-Co_3O_4/NPC composite in the OER was attributed to its favorable structure.
基金supported by the Shaanxi Yancheng Petroleum(Group)Co.,Ltd.,the National Natural Science Foundation of China(No.22202189)the Changjiang Scholars Program of the Ministry of Education of China.
文摘Thermal and photothermal catalytic selec-tive oxidation of isobutane to methacrylic acid(MAA)are comparatively studied over a keggin-type Cs2.9Cu0.34V0.49PMo12O40 het-eropolyacid acid.An introduction of light was observed to enhance both the i-C4H10 conversion and the MAA selectivity,and consequently the MAA formate rate,particularly at low temperatures.Characterization re-sults show that oxidation of methacrolein(MAL)to MAA is the rate-limiting step while UV light illumination promotes the oxidation ofσ-bonded MAL with OH groups toσ-bonded MAA on the catalyst surface.These results demonstrate a synergistic effect of thermal cataly-sis and photocatalysis in selective oxidation of isobutane to MAA,which suggests photother-mal catalysis as a promising strategy to catalyze the selective oxidation of higher hydrocar-bons at relative mild reaction conditions.
基金support provided by National Natural Science Foundation of China(21978243).
文摘The catalytic packing is the core component of the catalytic distillation,and how the catalyst exists in the packing has significant influence on the process.To investigate the effect of catalyst packings on the catalytic distillation process,the classical ethyl acetate reactive distillation system was utilized,and a supported catalytic packing(SCP)was prepared in comparison with the conventional tea-bag catalytic packing(TBP).Laboratory scale experiments showed that the ethyl acetate conversion of the SCP was superior to the TBP at a low catalyst loading.The effects of reaction kinetics,mass transfer performance and actual catalytic efficiency of the packings on this process were regarded as reasons and studied by combining the experiments and numerical simulation.Results suggested that the relatively immediate“in-situ separation”caused by the rapid reaction kinetics and better mass transfer performance of SCP may be a main reason for the difference of the conversion.
基金supported by the National Key Research and Development Program of China(2017YFB0602504)the General Program of National Natural Science Foundation of China(22178385).
文摘To produce low olefin gasoline with high octane number by Fischer-Tropsch (F-T) wax fluid catalytic cracking (FCC) process, operating conditions optimization were carried out in the pilot-scale riser and turbulent fluidized bed (TFB) FCC unit. The experimental results in the riser indicated that under the condition of low reaction temperature and regenerated catalyst temperature, large catalyst-to-oil weight ratio (C/O) and long reaction time, the gasoline olefin content could be reduced to 20.28 wt%, but there is large octane number loss owing to a great loss in high octane number olefin. Therefore, a novel FCC process using the TFB reactor was proposed to strengthen the aromatization reaction. The reaction performance of TFB reactor were investigated. The result demonstrated that the TFB reactor has more significant effect in reducing olefins and improving aromatics. At the expense of certain gasoline yield, the gasoline olefin content reduced to 23.70 wt%, aromatics content could increase to 26.79 wt% and the RON was up to 91.0. The comparison of reactor structure and fluidization demonstrated that the TFB reactor has higher catalyst bed density. The reaction heat and coke combustion heat was calculated indicating the feasibility of its industrial application of the TFB process.
基金financially supported by the National Natural Science Foundation of China (21908033,21576059,21666008)Fok Ying-Tong Education Foundation (161030)+1 种基金the Program of Introducing Talents of Discipline to Universities of China (111 Program,D20023)Guizhou Frontiers Science Center for Asymmetric Synthesis and Medicinal Molecules ([2020]004)。
文摘Transfer hydrogenation(TH) with in situ generated hydrogen donor is of great importance in reduction reactions, and an alternative strategy to traditional hydrogenation processes involving pressurized molecular hydrogen. Ammonia borane(NH3BH3, AB) is a promising material of hydrogen storage, and it has attracted much attention in reductive organic transformations owing to its high activity, good atom economy, nontoxicity, sustainability, and ease of transport and storage. This review focuses on summarizing the recent progress of AB-mediated TH reactions of diverse substrates including nitro compounds, nitriles, imines, alkenes, alkynes, carbonyl compounds(ketones and aldehydes), carbon dioxide,and N-and O-heterocycles. Syntheses protocols(metal-containing and metal-free), the effect of reaction parameters, product distribution, and variation of reactivity are surveyed, and the mechanism of each reaction involving the action mode of AB as well as structure-activity relationships is discussed in detail. Finally, perspectives are presented to highlight the challenges and opportunities for AB-enabled TH reactions of unsaturated compounds.
基金This work is supported by the National Key R&D Program of China(Grant No.2017YFB0103002)National Natural Science Foundation of China(Grant Nos.51771056,51371056,51701043 and 52071141)+4 种基金Equipment Preresearch Field Foundation(Grant No.6140721040101)Equipment Preresearch Sharing Technology(No.41421060201)Changzhou Leading Talents Project(Grant No.CQ20183020)333 Project in Jiangsu Province and the Priority Academic Program Development(PAPD)of Jiangsu Higher Education Institutions,Fundamental Research Funds for the Central Universities(Grant No.2021MS051)Interdisciplinary Innovation Program of North China Electric Power University(grant number XM2112355).
文摘Ni and carbon materials exhibit remarkable catalysis for the hydriding reaction of Mg.But the underlying mechanism of Ni/C hybrid catalysis is still unclear.In this work,density functional theory(DFT)calculation is applied to investigate the effect of Ni/C co-incorporation on the hydriding reaction of Mg crystal.The morphology and crystal structure of the Ni/C co-incorporated Mg sample show that the coincorporated structure is credible.The transition state searching calculation suggests that both the incorporations of Ni and C are beneficial for the H_(2) dissociation.But Ni atom has a dramatic improvement for H_(2) dissociation and makes the H diffusion become limiting step of the hyriding reaction.The Ni dz_(2)orbit and H s orbit accept the electrons and combine together compactly,while the Ni d_(xy) orbit is half-occupied.The catalytic effect of Ni on H_(2) dissociation can be ascribed to the bridging effect of Ni d_(xy) orbit.The incorporation of C can weaken the over-strong interaction between Ni and H which hindered the H diffusion on Mg(0001).The Ni/C co-incorporated Mg(0001)shows the best performance during hyriding reaction compared with the clean and single incorporated Mg(0001).
文摘Catalytic co-cracking of Fischer–Tropsch(FT) light distillate and methanol combines highly endothermic olefin cracking reaction with exothermic methanol conversion over ZSM-5 catalyst to produce light olefins through a nearly thermoneutral process. The kinetic behavior of co-cracking reactions was investigated by different feed conditions: methanol feed only, olefin feed only and co-feed of methanol with olefins or F–T distillate. The results showed that methanol converted to C2–C6 olefins in first-order parallel reaction at low space time, methylation and oligomerization–cracking prevailed for the co-feed of methanol and C2–C5 olefins, while for C6–C8 olefins,monomolecular cracking was the dominant reaction whether fed alone or co-fed with methanol. For FT distillate and methanol co-feed, alkanes were almost un-reactive, C3–C5 olefins were obtained as main products, accounting for 71 wt% for all products. A comprehensive co-cracking reaction scheme was proposed and the model parameters were estimated by the nonlinear least square method. It was verified by experimental data that the kinetic model was reliable to predict major product distribution for co-cracking of FT distillate with methanol and could be used for further reactor development and process design.
文摘In this study a mathematical model of a small scale single pellet for the oxidative coupling of methane(OCM)over titanite pervoskite is developed.The method is based on a computational fluid dynamics(CFD)code which known as Fluent may be adopted to model the reactions that take place inside the porous catalyst pellet.The steady state single pellet model is coupled with a kinetic model and the intra-pellet concentration profiles of species are provided.Subsequent to achieving this goal,a nonlinear reaction network consisting of nine catalytic reactions and one gas phase reaction as an external program is successfully implemented to CFD-code as a reaction term in solving the equations.This study is based on the experimental design which is conducted in a differential reactor with a Sn/BaTiO3 catalyst(7-8 mesh) at atmospheric pressure,GHSV of 12000 h-1,ratio of methane to oxygen of 2,and three different temperatures of 1023,1048 and 1073 K.The modeling results such as selectivity and conversion at the pellet exit are in good agreement with the experimental data.Therefore,it is suggested that to achieve high yield in OCM process the modeling of the single pellet should be considered as the heart of catalytic fixed bed reactor.
基金This work was financially supported by the Teaching Reform Study Program of Ludong University (No.Y0715).
文摘Ce0.5Zr0.5O2 solid solution was successfully synthesized using cerium nitrate, zirconium nitrate, and urea as raw materials by the microwave irradiation method and characterized by X-ray diffraction, fluorescence spectrum, transmission electron microscopy, and infrared spectrum. Its acid catalytic activity was evaluated in the esterification reaction of acetic acid and n-butyl alcohol. The results show that Ce0.5Zr0.5O2 solid solution has cubic fluorite structure, and its particle diameter is in the nanometer scale. As a sort of solid acid, it possesses a higher acid catalytic activity and can be easily separated from reaction liquids. It can be used for several times, and basically, its activity keeps constant. The proton acid sites and Lewis acid sites exist in the structure of Ce0.5Zr0.5O2 solid solution.
基金National Natural Science Foundation of China(No.20076036Tianjin University C1 National Laboratory Project
文摘Pd/LaxPbyMnOz, Pd/C, Pd/molecular sieve and Pd-heteropoly acid catalysts for direct synthesis of diphenyl carbonate (DPC) by heterogeneous catalytic reaction were compared and the results of DPC synthesis indicated that the catalyst Pd/LaxPbyMnOz had higher activity. The Pd/LaxPbyMnOz catalyst and the support was characterized by XRD, SEM and TEM, the main phase was La0.62Pb0.38MnO3 and the average diameter could be about 25.4 nm. The optimum conditions for synthesis of DPC with Pd/LaxPbyMnOz were determined by orthogonal experiments and the experimental results showed that reaction temperature was the first factor of effect on the selectivity and yield of DPC, and the concentration of O2 in gas phase also had significant effect on selectivity of DPC. The optimum reaction conditions were catMyst/phenol mass ratio 1 to 50, pressure 4.5 MPa,volume concentration of O2 25%, reaction temperature 60° and reaction time 4 h. The maximum yield and average selectivity could reach 13% and 97% respectively in the batch operation.
文摘Approximate analytical expressions of overall effectiveness factors for parallel catalytic reac-tions occurring in a spherical catalyst pellet with both internal and external mass transfer resistancesare obtained after taking the information given by asymptotic solutions valid for small and largevalues of Thiele moduli.This approximate procedure is feasible for power law as well asLangmuir-Hinshelwood kinetics and the agreement between the approximation and the numerical re-sults is good enough for practical purposes.Moreover,the method does not require any iterative ortrial-and-error computation,and can be conveniently applied in most practical calculations for reac-tors giving reliable results.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11804200,11974222,11904214,and 11774208)the Project of Shandong Province Higher Educational Science and Technology Program(Grant No.J18KZ011)+3 种基金the Taishan Scholars Program of Shandong Province(Grant No.tsqn201812104)the Qingchuang Science and Technology Plan of the Shandong Province,China(Grant Nos.2019KJJ014 and 2019KJJ017)China Postdoctoral Science Foundation(Grant No.2019M662423)the Natural Science Foundation of Shandong Province,China(Grant No.ZR201910280104).
文摘The efficient production of hydrogen through electrocatalytic decomposition of water has broad prospects in modern energy equipment.However,the catalytic efficiency and durability of hydrogen evolution catalyst are still very deficient,which need to be further explored.Here in this work,we prove that introducing a graphene layer(Gr)between the molybdenum disulfide and nickel foam(Ni-F)substrate can greatly improve the catalytic performance of the hybrid.Owing to the excitation of local surface plasmon resonance(LSPR)of gold nanoparticles(NPs),the electrocatalytic hydrogen releasing activity of the MoS_(2)/Gr/Ni-F heterostructure is greatly improved.This results in a significant increase in the current density of AuNPs/MoS_(2)/Gr/Ni-F composite material under light irradiation and in the dark at 0.2 V(versus reversible hydrogen electrode(RHE)),which is much better than in MoS_(2)/Gr/Ni-F composite materials.The enhancement of hydrogen release can be attributed to the injection of hot electrons into MoS_(2)/Gr/Ni-F by AuNPs,which will improve the electron density of MoS_(2)/Gr/Ni-F,promote the reduction of H_(2)O,and further reduce the activation energy of the electrocatalyst hydrogen evolution reaction(HER).We also prove that the introduction of graphene can improve its stability in acidic catalytic environments.This work provides a new way of designing efficient water splitting system.
文摘The catalytic efficiency of modified nanodiamonds (MND) in reactions of interaction between organic compounds was demonstrated on the example of azocoupling reaction (hydrogen peroxide-4-aminoantipyrine-phenol). It was found that catalytic action of MND was caused by redox active metal ions of Fe and Cu located on the MND surface. The neutralization of the ions significantly decreased catalytic properties of MND.
文摘A series of lanthanide sulfates coordination complexes, Ln2(SO4)3(H2O)8 (Ln = Pr (1), Nd (2), Tb (3), Sm (4), Dy (5), Gd (7), Ho (8)), and EuK(SO4)2 (6), were constructed by the reaction in situ of lanthanide ions (Ln3+) with flexible dodecanedioic acid and rigid aromatic 5-sulfosalicylic acid under hydrothermal conditions. All of them were characterized by elemental analysis, IR spectroscopy, and single-crystal X-ray diffraction. The crystal structures and coordination modes of metal centers and sulfate ions, as well as the novel reaction mechanism and different conditions of lanthanide ions and 5-sulfosalicylic acid to form the series of lanthanide sulfate complexes, were discussed in detail. Solid-state properties for these crystalline materials, such as thermal stability and powder X-ray diffraction have been investigated. Additionally, the photoluminescent characterizations of the complexes 3, 4, 5 and 6, and the catalytic properties of all the complexes about cyclohexane being oxidized into cyclohexanone/cyclohexanol were investigated and compared.
文摘A new type of macro-micro-macro triple electrode is fabricated. The kinetic equation is obtained by using the decrease in collection current to determine the kinetic constant of homogeneous catalytic reaction, the method can be used to study homogeneous chemical reaction with any magnitude of kinetic constant, and overcomes the disadvantages that the microelectrode is only suitable for fast catalytic reaction.