Engineering transition metal compounds(TMCs)catalysts with excellent adsorption-catalytic ability has been one of the most effec-tive strategies to accelerate the redox kinetics of sulfur cathodes.Herein,this review f...Engineering transition metal compounds(TMCs)catalysts with excellent adsorption-catalytic ability has been one of the most effec-tive strategies to accelerate the redox kinetics of sulfur cathodes.Herein,this review focuses on engineering TMCs catalysts by cation doping/anion doping/dual doping,bimetallic/bi-anionic TMCs,and TMCs-based heterostructure composites.It is obvious that introducing cations/anions to TMCs or constructing heterostructure can boost adsorption-catalytic capacity by regulating the electronic structure including energy band,d/p-band center,electron filling,and valence state.Moreover,the elec-tronic structure of doped/dual-ionic TMCs are adjusted by inducing ions with different electronegativity,electron filling,and ion radius,resulting in electron redistribution,bonds reconstruction,induced vacancies due to the electronic interaction and changed crystal structure such as lat-tice spacing and lattice distortion.Different from the aforementioned two strategies,heterostructures are constructed by two types of TMCs with different Fermi energy levels,which causes built-in electric field and electrons transfer through the interface,and induces electron redistribution and arranged local atoms to regulate the electronic structure.Additionally,the lacking studies of the three strategies to comprehensively regulate electronic structure for improving catalytic performance are pointed out.It is believed that this review can guide the design of advanced TMCs catalysts for boosting redox of lithium sulfur batteries.展开更多
Hydrogen sulfide(H_(2)S) not only presents significant environmental concerns but also induces severe corrosion in industrial equipment,even at low concentrations.Among various technologies,the selective oxidation of ...Hydrogen sulfide(H_(2)S) not only presents significant environmental concerns but also induces severe corrosion in industrial equipment,even at low concentrations.Among various technologies,the selective oxidation of hydrogen sulfide(SOH_(2)S) to elemental sulfur(S) has emerged as a sustainable and environmentally friendly solution.Due to its unique properties,iron oxide has been extensively investigated as a catalyst for SOH_(2)S;however,rapid deactivation has remained a significant drawback.The causes of iron oxide-based catalysts deactivation mechanisms in SOH_(2)S,including sulfur or sulfate deposition,the transformation of iron species,sintering and excessive oxygen vacancy formation,and active site loss,are thoroughly examined in this review.By focusing on the deactivation mechanisms,this review aims to provide valuable insights into enhancing the stability and efficiency of iron-based catalysts for SOH_(2)S.展开更多
Lithium-sulfur(Li-S) batteries have attracted considerable attention as one of the most appealing energy storage systems.Strenuous efforts have been devoted to tackling the tremendous challenges,mainly pertaining to t...Lithium-sulfur(Li-S) batteries have attracted considerable attention as one of the most appealing energy storage systems.Strenuous efforts have been devoted to tackling the tremendous challenges,mainly pertaining to the severe shuttle effect,sluggish redox kinetics and lithium dendritic growth.Single-atomic mediators as promising candidates exhibit impressive performance in addressing these intractable issues.Related research often utilizes a trial-and-error approach,proposing solutions to fabricate single-atomic materials with diversified features.However,comprehensive review articles especially targeting demand-driven preparation are still in a nascent stage.Inspired by these considerations,this review summarizes the design of single-atomic mediators based on the application case-studies in LiS batteries and other metal-sulfur systems.Emerging preparation routes represented by chemical vapor deposition technology are introduced in a demand-oriented classification.Finally,future research directions are proposed to foster the advancement of single-atomic mediators in Li-S realm.展开更多
Methacrylic acid,an important organic chemical,is commercially manufactured starting from fossil feedstock.The decarboxylation of itaconic acid derived for biomass is a green route to the synthesis of methacrylic acid...Methacrylic acid,an important organic chemical,is commercially manufactured starting from fossil feedstock.The decarboxylation of itaconic acid derived for biomass is a green route to the synthesis of methacrylic acid.In view of the problems existing in the researches on this route such as use of noble metal catalyst,harsh reaction conditions and low desired-product yield,we prepared a series of hydroxyapatite catalysts with different Ca/P molar ratios and evaluated their catalytic performance.The results showed that the hydroxyapatite catalyst with a Ca/P molar ratio of 1.58 had the best catalytic activity.The highest yield of MAA up to 61.2%was achieved with basically complete conversion of itaconic acid under the suitable reaction conditions of 1 equivalent of NaOH,2 MPa of N_(2),250℃,and 2 h.On this basis,a reaction network for the decarboxylation of itaconic acid to methacrylic acid catalyzed by hydroxyapatite was established.With the aid of catalyst characterization using X-ray powder diffraction,NH3/CO2 temperature-programmed desorption,N_(2)physisorption,inductively coupled plasma optical emission spectrometry,and scanning electron microscopy,we found that the distribution of surface acid sites and basic sites,crystal growth orientation,texture properties and morphology of hydroxyapatite varied with the Ca/P molar ratio.Furthermore,the change of the crystal growth orientation and its influence on the surface acidity and alkalinity were clarified.展开更多
It is useful for practical operation to study the rules of production of propylene by the catalytic conversion of heavy oil in FCC (fluid catalytic cracking). The effects of temperature and C/O ratio (catalyst to o...It is useful for practical operation to study the rules of production of propylene by the catalytic conversion of heavy oil in FCC (fluid catalytic cracking). The effects of temperature and C/O ratio (catalyst to oil weight ratio) on the distribution of the product and the yield of propylene were investigated on a micro reactor unit with two model catalysts, namely ZSM-5/Al2O3 and USY/Al2O3, and Fushun vacuum gas oil (VGO) was used as the feedstock. The conversion of heavy oil over ZSM-5 catalyst can be comparable to that of USY catalyst at high temperature and high C/O ratio. The rate of conversion of heavy oil using the ZSM-5 equilibrium catalyst is lower compared with the USY equilibrium catalyst under the general FCC conditions and this can be attributed to the poor steam ability of the ZSM-5 equilibrium catalyst. The difference in pore topologies of USY and ZSM-5 is the reason why the principal products for the above two catalysts is different, namely gasoline and liquid petroleum gas (LPG), repspectively. So the LPG selectivity, especially the propylene selectivity, may decline if USY is added into the FCC catalyst for maximizing the production of propylene. Increasing the C/O ratio is the most economical method for the increase of LPG yield than the increase of the temperature of the two model catalysts, because the loss of light oil is less in the former case. There is an inverse correlation between HTC (hydrogen transfer coefficient) and the yield of propylene, and restricting the hydrogen transfer reaction is the more important measure in increasing the yield of propylene of the ZSM-5 catalyst. The ethylene yield of ZSM-5/A1203 is higher, but the gaseous side products with low value are not enhanced when ZSM-5 catalyst is used. Moreover, for LPG and the end products, dry gas and coke, their ranges of reaction conditions to which their yields are dependent are different, and that of end products is more severe than that of LPG. So it is clear that maximizing LPG and propylene and restricting dry gas and coke can be both achieved via increasing the severity of reaction conditions among the range of reaction conditions which LPG yield is sensitive to.展开更多
The overall performance of metal catalysts can be efficiently adjusted by modifying carbon carriers with different valence sulfur precursors.The wet impregnation technique successfully prepared carbon material carrier...The overall performance of metal catalysts can be efficiently adjusted by modifying carbon carriers with different valence sulfur precursors.The wet impregnation technique successfully prepared carbon material carriers doped with varying sources of sulfur(Na_(2)SO_(4),NaHSO_(3),Na_(2)S·9H_(2)O).Palladium carbon catalysts doped with different sulfur precursors had been prepared with the aid of the liquid-phase reduction method of the selective hydrogenation of o-chloronitrobenzene(o-CNB)to o-chloroaniline(o-CAN).The catalyst prepared for Na_(2)S·9H_(2)O as a precursor has excellent performance,and the selectivity for o-CAN is more than 99.9%at 100%conversion.In addition,the characterization results show that with the decrease of S valence,the electronic effect between S and Pd increases,and the outer electron shift of Pd increases,which reduces the adsorption and dissociation ability of Pd to hydrogen,resulting in excellent selectivity.The effects provided a good idea for the hydrogenation of o-CNB and a different point of view on sulfur doping in a variety of hydrogenation reactions.展开更多
Effects of carbon nanotubes (CNT) and alumina (γ-Al2O3) supports on the catalytic activities of hydrodesulfurization (HDS) process over Co- Mo catalyst have been studied. XRD results indicated that the main act...Effects of carbon nanotubes (CNT) and alumina (γ-Al2O3) supports on the catalytic activities of hydrodesulfurization (HDS) process over Co- Mo catalyst have been studied. XRD results indicated that the main active phases in CNT and γ-Al2O3 supported Co-Mo catalysts are MoO2 and MOO3, respectively. The TPR results reveal that the reduction peak temperatures of the active species on CNT supported Co-Mo catalyst is lower than those on alumina supported Co-Mo catalyst, indicating that the CNT supports favor the reduction of active species. Catalytic evaluation results displayed that the sulfur content in the reaction products on the CNT supported Co-Mo catalyst is lower than that on the alumina supported Co-Mo catalyst if the HDS reaction was carried out at a temperature above 583 K.展开更多
The thermal dissolved sulfuration technology is brought forward and performed based on the characteristic of low grade lead-zinc oxide ore in lanpin. Using sulfur as the sulphidizing agent in the experiment, the oxide...The thermal dissolved sulfuration technology is brought forward and performed based on the characteristic of low grade lead-zinc oxide ore in lanpin. Using sulfur as the sulphidizing agent in the experiment, the oxides in the sandstone and ignimbrite are changed into sulfides. The disproportionation reaction of sulfur in a solution is confirmed as 4S+3H2O=2S^2-+S2O3^2--+6H^+. The dynamics process is studied and the first-order reaction rate equation -1n(1-a)=ktt is obtained. The effects of the reactive products, stirring speed, dosage of sulfuration agent, value of pH and sulphidizing temperature on the sulfuration of oxide ore are investigated. The results indicate that the reactive apparent activation energy is 100.8 kJ/mol and the sulfuration ratio of lead-zinc oxide ore reaches 60% under the conditions of pH 5.9-7.5, the sulfuration temperature of 130 ℃, sulfuration time of 180 min and the stirring speed of 800 r/min.展开更多
Development of efficient and promising bifunctional electrocatalysts for oxygen reduction and evolutionreactions is desirable. Herein, cobalt nanoparticles embedded in nitrogen and sulfur co-doped carbonnanotubes(Co@N...Development of efficient and promising bifunctional electrocatalysts for oxygen reduction and evolutionreactions is desirable. Herein, cobalt nanoparticles embedded in nitrogen and sulfur co-doped carbonnanotubes(Co@NSCNT) were prepared by a facile pyrolytic treatment. The cobalt nanoparticles and co-doping of nitrogen and sulfur can improve the electron donor-acceptor characteristics of the carbon nan-otubes and provide more active sites for catalytic oxygen reduction and evolution reactions. The preparedCo@NSCNT, annealed at 900℃, showed excellent electrocatalytic performance and better durability thancommercial platinum catalysts. Additionally, Co@NSCNT-900 catalysts exhibited comparable onset poten-tials and Tafel slopes to ruthenium oxide. Overall, Co@NSCNT showed high activity and improved dura-bility for both oxygen evolution and reduction reactions.展开更多
The effect of polycyclic aromatic hydrocarbons(PAHs)on the stability of the hydrogenation catalyst for production of ultra-low sulfur diesel was studied in a pilot plant using Ni-Mo-W/γ-Al_(2)O_(3)catalyst.The mechan...The effect of polycyclic aromatic hydrocarbons(PAHs)on the stability of the hydrogenation catalyst for production of ultra-low sulfur diesel was studied in a pilot plant using Ni-Mo-W/γ-Al_(2)O_(3)catalyst.The mechanisms of catalyst deactivation were analyzed by the methods of elemental analysis,nitrogen adsorption-desorption,thermogravimetry-mass spectrometry(TG-MS)technology,X-ray photoelectron spectroscopy(XPS)and high resolution transmission electron microscopy(HRTEM).The results demonstrated that PAHs had little effect on the activity of catalyst at the beginning of operation,during which the reaction temperature was increased by only 1-4℃.However,the existence of PAHs significantly accelerated the deactivation of catalyst and weakened the stability of catalyst.This phenomenon could be explained by the reason that the catalyst deactivation is not only related to the formation of carbon deposit,but is also closely related to the loss of pore volume and the decrease of Ni-W-S phase ratio after adding PAHs.展开更多
In this work, Zr-M(M=Cu, Mn, Ce) type sulfur transfer agent was prepared by impregnation method. Under the condition similar to that in the regenerator of FCC units, the influence of different active metal components ...In this work, Zr-M(M=Cu, Mn, Ce) type sulfur transfer agent was prepared by impregnation method. Under the condition similar to that in the regenerator of FCC units, the influence of different active metal components and their contents on sulfur transfer agent were investigated. Moreover, the crystalline structure of sulfur transfer agent was characterized by X-ray diffraction(XRD) and Fourier transforms infrared spectroscopy(FT-IR). The result showed that the Zr-Mn sulfur transfer agent could effectively reduce the SO2 content in FCC regenerator flue gas, featuring high SO2 adsorption capacity. The sulfur transfer agent was inactivated in 40—60 min during the test. In the course of reduction reaction, after several reaction cycles, the formation of SO2 ceased and only H2 S was detected as the reduction product.展开更多
The effect of boron on the performance of MoO_3/CeO_2–Al_2O_3 catalysts, which were prepared with impregnation method, was investigated. The catalysts were characterized with N_2 adsorption–desorption, XRD, H_2-TPR,...The effect of boron on the performance of MoO_3/CeO_2–Al_2O_3 catalysts, which were prepared with impregnation method, was investigated. The catalysts were characterized with N_2 adsorption–desorption, XRD, H_2-TPR, and NH_3-TPD, and were tested in sulfur-resistant methanation. The results indicated that the MoO_3/CeO_2–Al_2O_3 catalysts modified by boron showed higher catalytic performance in sulfur-resistant methanation. The CO conversion increased from 47% to 62% with 0.5 wt% boron content. When the content of boron was under 0.5 wt%, the results suggested there was an increase in the amorphous form of MoO_3 caused by the generation of weak and intermediate acid sites, which had weakened the interaction between the active components and supports. While, the catalyst added 2.0 wt% boron showed the strong acid sites and the largest crystalline size resulting in the uneven distribution of ceria.展开更多
The Mo modified Ni/Al_2O_3 catalysts were prepared and sulfided at different temperatures, and their catalytic activity for thioetherification of mercaptans and olefins(or dienes), hydrogenation of dienes and olefins ...The Mo modified Ni/Al_2O_3 catalysts were prepared and sulfided at different temperatures, and their catalytic activity for thioetherification of mercaptans and olefins(or dienes), hydrogenation of dienes and olefins in the thioetherification process using fluidized catalytic cracking(FCC) naphtha as the feedstock was investigated. In order to disclose the correlation between the physicochemical characteristics of catalysts and their catalytic activity, the surface structures and properties of the catalysts sulfided at different temperatures were characterized by the high resolution transmission electronic microscopy(HRTEM), X-ray photoelectron spectroscopy(XPS) and H2-temperature programmed reduction(H_2-TPR) technique. The results showed that an increase of sulfurization temperature not only could promote the sulfurization degree of active metals on the catalysts, but also could adjust the micro-morphology of active species. These changes could improve the catalytic performance of thioetherification, and hydrogenation of dienes and olefins. However, an excess sulfurization temperature was more easily to upgrade the ability of the catalyst for hydrogenation of olefins, which could lead to a decrease of the octane number of the product. It was also showed that a moderate sulfurization temperature not only could improve the catalytic performance of thioetherification and hydrogenation of dienes but also could control hydrogenation of olefins.展开更多
Vapor-phase nitration of benzene over solid acid catalyst is expected to be a clean process with no sulfuric acid waste. We investigated this process over solid acidic catalysts utilizing diluted nitric acid (60-70%)...Vapor-phase nitration of benzene over solid acid catalyst is expected to be a clean process with no sulfuric acid waste. We investigated this process over solid acidic catalysts utilizing diluted nitric acid (60-70%) as nitrating agent, and found that supported sulfuric acid catalyst exhibited a very high catalytic activity. Under the conditions of reaction temperature 160-170℃, space velocity (SV) 1200 h-1, the yield and the space-time yield (STY) of nitrobenzene (NB) based on HNO3 were more than 98% and 0.75 kg穔gcat-1穐-1 over 10% H2SO4/SiO2 (by weight) catalyst respectively.展开更多
CeO_2–CaO–Pd/HZSM-5 catalyst was prepared for the dimethyl ether(DME) one-step synthesis in a continuous fixed-bed micro-reactor from the sulfur-containing syngas. The catalytic stability over hybrid catalyst of Ce...CeO_2–CaO–Pd/HZSM-5 catalyst was prepared for the dimethyl ether(DME) one-step synthesis in a continuous fixed-bed micro-reactor from the sulfur-containing syngas. The catalytic stability over hybrid catalyst of CeO_2–CaO–Pd/HZSM-5 was investigated to ensure that the kinetics experimental results were not significantly influenced by induction period and catalytic deactivation. A large number of kinetic data points(40 sets) were obtained over a range of temperature(240–300 °C), pressure(3–4 MPa), gas hourly space velocity(GHSV)(2000–3000 L·kg^(-1)·h^(-1)) and H_2/CO mole ratio(2–3). Kinetic model for the methanol synthesis reaction and the dehydration of methanol were obtained separately according to reaction mechanism and Langmuir–Hinshelwood mechanism. Regression parameters were investigated by the method combining the simplex method and Runge–Kutta method. The model calculations were in appropriate accordance with the experimental data.展开更多
Zirconia-loaded sulfuric acid (SO2-/ZrO2) catalysts were prepared by impregnation method, molded by punch tablet machine and characterized by X-ray diffraction. SO4^2-/ZrO2 catalyst was used to obtain glycerol triac...Zirconia-loaded sulfuric acid (SO2-/ZrO2) catalysts were prepared by impregnation method, molded by punch tablet machine and characterized by X-ray diffraction. SO4^2-/ZrO2 catalyst was used to obtain glycerol triacetate (GTA) directly from glycerin. The effect of some factors, such as different temperatures of calcination and catalysts molded or not, on the reusable times of catalysts and the yield of GTA were investigated. The optimum reaction conditions were shown as follows: the reaction temperature was 403 K; the reaction time continued for 8 h; the amount of molded catalysts was 5 wt% of glycerin and the molar ratio of glycerin to acetic acid was 1 : 8. The yield of GTA was 97.93% under the optimum condition.展开更多
Application of sulfuric acid immobilized on silica gel as an efficient and benign catalyst has been explored in the syn-thesis of 2,4,5-Triaryl-1H-imidazoles via condensation reaction of benzil or benzoin, aldehyde an...Application of sulfuric acid immobilized on silica gel as an efficient and benign catalyst has been explored in the syn-thesis of 2,4,5-Triaryl-1H-imidazoles via condensation reaction of benzil or benzoin, aldehyde and ammonium acetate. The key advantages of this process are high yields, cost effectiveness of catalyst, easy work-up, purification of products by non-chromatographic method and the reusability of the H2SO4.SiO2 catalyst.展开更多
A series of modifiedγ-Al_2O_3supported iron-based catalysts(M-Fe/γ-Al_2O_3)was developed to reduce SO_2in actual smelter off-gases using CO–H_2gas mixture as reducing agent for sulfur production.Used as modifiers,t...A series of modifiedγ-Al_2O_3supported iron-based catalysts(M-Fe/γ-Al_2O_3)was developed to reduce SO_2in actual smelter off-gases using CO–H_2gas mixture as reducing agent for sulfur production.Used as modifiers,three metal additives—Ni,Co,and Ce were added to Fe/γ-Al_2O_3catalysts.Changes in catalyst structure and active phase were characterized with X-ray diffraction,XPS,SEM,and EDS.The reduction ability of catalysts was exhibited via CO-TPR.The prepared catalysts only need to be pre-reacted for a period of time,eliminating the need for presulfidation treatment.Reaction conditions were optimized in a fixed bed reactor to achieve high SO_2conversion and sulfur selectivity.XRD characterization was carried out to verify the resulting sulfur products.Combining in situ infrared characterization and catalyst evaluation of support and active component,the reaction mechanism was investigated and proposed.展开更多
基金The authors acknowledge funding from National Natural Science Foundation of China(52302307)Shaanxi Province(2023-ZDLGY-24,2023-JC-QN-0473)+2 种基金project funded by China Postdoctoral Science Foundation(2023MD734210)the Open Foundation of State Key Laboratory for Advanced Metals and Materials(2022-Z01)Shaanxi Provincial Department of Education industrialization project(21JC018).
文摘Engineering transition metal compounds(TMCs)catalysts with excellent adsorption-catalytic ability has been one of the most effec-tive strategies to accelerate the redox kinetics of sulfur cathodes.Herein,this review focuses on engineering TMCs catalysts by cation doping/anion doping/dual doping,bimetallic/bi-anionic TMCs,and TMCs-based heterostructure composites.It is obvious that introducing cations/anions to TMCs or constructing heterostructure can boost adsorption-catalytic capacity by regulating the electronic structure including energy band,d/p-band center,electron filling,and valence state.Moreover,the elec-tronic structure of doped/dual-ionic TMCs are adjusted by inducing ions with different electronegativity,electron filling,and ion radius,resulting in electron redistribution,bonds reconstruction,induced vacancies due to the electronic interaction and changed crystal structure such as lat-tice spacing and lattice distortion.Different from the aforementioned two strategies,heterostructures are constructed by two types of TMCs with different Fermi energy levels,which causes built-in electric field and electrons transfer through the interface,and induces electron redistribution and arranged local atoms to regulate the electronic structure.Additionally,the lacking studies of the three strategies to comprehensively regulate electronic structure for improving catalytic performance are pointed out.It is believed that this review can guide the design of advanced TMCs catalysts for boosting redox of lithium sulfur batteries.
基金supported by Thailand Science Research and Innovation Fund Chulalongkorn University,Thailand(IND66210014)。
文摘Hydrogen sulfide(H_(2)S) not only presents significant environmental concerns but also induces severe corrosion in industrial equipment,even at low concentrations.Among various technologies,the selective oxidation of hydrogen sulfide(SOH_(2)S) to elemental sulfur(S) has emerged as a sustainable and environmentally friendly solution.Due to its unique properties,iron oxide has been extensively investigated as a catalyst for SOH_(2)S;however,rapid deactivation has remained a significant drawback.The causes of iron oxide-based catalysts deactivation mechanisms in SOH_(2)S,including sulfur or sulfate deposition,the transformation of iron species,sintering and excessive oxygen vacancy formation,and active site loss,are thoroughly examined in this review.By focusing on the deactivation mechanisms,this review aims to provide valuable insights into enhancing the stability and efficiency of iron-based catalysts for SOH_(2)S.
基金supported by the National Natural Science Foundation of China(22179089)the Postgraduate Research&Practice Innovation Program of Jiangsu Province(KYCX23_3245)support from Suzhou Key Laboratory for Advanced Carbon Materials and Wearable Energy Technologies,Suzhou,China。
文摘Lithium-sulfur(Li-S) batteries have attracted considerable attention as one of the most appealing energy storage systems.Strenuous efforts have been devoted to tackling the tremendous challenges,mainly pertaining to the severe shuttle effect,sluggish redox kinetics and lithium dendritic growth.Single-atomic mediators as promising candidates exhibit impressive performance in addressing these intractable issues.Related research often utilizes a trial-and-error approach,proposing solutions to fabricate single-atomic materials with diversified features.However,comprehensive review articles especially targeting demand-driven preparation are still in a nascent stage.Inspired by these considerations,this review summarizes the design of single-atomic mediators based on the application case-studies in LiS batteries and other metal-sulfur systems.Emerging preparation routes represented by chemical vapor deposition technology are introduced in a demand-oriented classification.Finally,future research directions are proposed to foster the advancement of single-atomic mediators in Li-S realm.
基金supported by the National Natural Science Foundation of China(Grant No.21978066)Basic Research Program of Hebei Province for Natural Science Foundation and Key Basic Research Project(Grant No.18964308D)the Key Program of Natural Science Foundation of Hebei Province(Grant No.B2020202048).
文摘Methacrylic acid,an important organic chemical,is commercially manufactured starting from fossil feedstock.The decarboxylation of itaconic acid derived for biomass is a green route to the synthesis of methacrylic acid.In view of the problems existing in the researches on this route such as use of noble metal catalyst,harsh reaction conditions and low desired-product yield,we prepared a series of hydroxyapatite catalysts with different Ca/P molar ratios and evaluated their catalytic performance.The results showed that the hydroxyapatite catalyst with a Ca/P molar ratio of 1.58 had the best catalytic activity.The highest yield of MAA up to 61.2%was achieved with basically complete conversion of itaconic acid under the suitable reaction conditions of 1 equivalent of NaOH,2 MPa of N_(2),250℃,and 2 h.On this basis,a reaction network for the decarboxylation of itaconic acid to methacrylic acid catalyzed by hydroxyapatite was established.With the aid of catalyst characterization using X-ray powder diffraction,NH3/CO2 temperature-programmed desorption,N_(2)physisorption,inductively coupled plasma optical emission spectrometry,and scanning electron microscopy,we found that the distribution of surface acid sites and basic sites,crystal growth orientation,texture properties and morphology of hydroxyapatite varied with the Ca/P molar ratio.Furthermore,the change of the crystal growth orientation and its influence on the surface acidity and alkalinity were clarified.
文摘It is useful for practical operation to study the rules of production of propylene by the catalytic conversion of heavy oil in FCC (fluid catalytic cracking). The effects of temperature and C/O ratio (catalyst to oil weight ratio) on the distribution of the product and the yield of propylene were investigated on a micro reactor unit with two model catalysts, namely ZSM-5/Al2O3 and USY/Al2O3, and Fushun vacuum gas oil (VGO) was used as the feedstock. The conversion of heavy oil over ZSM-5 catalyst can be comparable to that of USY catalyst at high temperature and high C/O ratio. The rate of conversion of heavy oil using the ZSM-5 equilibrium catalyst is lower compared with the USY equilibrium catalyst under the general FCC conditions and this can be attributed to the poor steam ability of the ZSM-5 equilibrium catalyst. The difference in pore topologies of USY and ZSM-5 is the reason why the principal products for the above two catalysts is different, namely gasoline and liquid petroleum gas (LPG), repspectively. So the LPG selectivity, especially the propylene selectivity, may decline if USY is added into the FCC catalyst for maximizing the production of propylene. Increasing the C/O ratio is the most economical method for the increase of LPG yield than the increase of the temperature of the two model catalysts, because the loss of light oil is less in the former case. There is an inverse correlation between HTC (hydrogen transfer coefficient) and the yield of propylene, and restricting the hydrogen transfer reaction is the more important measure in increasing the yield of propylene of the ZSM-5 catalyst. The ethylene yield of ZSM-5/A1203 is higher, but the gaseous side products with low value are not enhanced when ZSM-5 catalyst is used. Moreover, for LPG and the end products, dry gas and coke, their ranges of reaction conditions to which their yields are dependent are different, and that of end products is more severe than that of LPG. So it is clear that maximizing LPG and propylene and restricting dry gas and coke can be both achieved via increasing the severity of reaction conditions among the range of reaction conditions which LPG yield is sensitive to.
基金financially supported by the National Natural Science Foundation of China(22078292,22008212,U20A20119,21776258)。
文摘The overall performance of metal catalysts can be efficiently adjusted by modifying carbon carriers with different valence sulfur precursors.The wet impregnation technique successfully prepared carbon material carriers doped with varying sources of sulfur(Na_(2)SO_(4),NaHSO_(3),Na_(2)S·9H_(2)O).Palladium carbon catalysts doped with different sulfur precursors had been prepared with the aid of the liquid-phase reduction method of the selective hydrogenation of o-chloronitrobenzene(o-CNB)to o-chloroaniline(o-CAN).The catalyst prepared for Na_(2)S·9H_(2)O as a precursor has excellent performance,and the selectivity for o-CAN is more than 99.9%at 100%conversion.In addition,the characterization results show that with the decrease of S valence,the electronic effect between S and Pd increases,and the outer electron shift of Pd increases,which reduces the adsorption and dissociation ability of Pd to hydrogen,resulting in excellent selectivity.The effects provided a good idea for the hydrogenation of o-CNB and a different point of view on sulfur doping in a variety of hydrogenation reactions.
文摘Effects of carbon nanotubes (CNT) and alumina (γ-Al2O3) supports on the catalytic activities of hydrodesulfurization (HDS) process over Co- Mo catalyst have been studied. XRD results indicated that the main active phases in CNT and γ-Al2O3 supported Co-Mo catalysts are MoO2 and MOO3, respectively. The TPR results reveal that the reduction peak temperatures of the active species on CNT supported Co-Mo catalyst is lower than those on alumina supported Co-Mo catalyst, indicating that the CNT supports favor the reduction of active species. Catalytic evaluation results displayed that the sulfur content in the reaction products on the CNT supported Co-Mo catalyst is lower than that on the alumina supported Co-Mo catalyst if the HDS reaction was carried out at a temperature above 583 K.
基金supported by Cooperated Project of Academy and College Yunnan province(2003CBALA02P023)
文摘The thermal dissolved sulfuration technology is brought forward and performed based on the characteristic of low grade lead-zinc oxide ore in lanpin. Using sulfur as the sulphidizing agent in the experiment, the oxides in the sandstone and ignimbrite are changed into sulfides. The disproportionation reaction of sulfur in a solution is confirmed as 4S+3H2O=2S^2-+S2O3^2--+6H^+. The dynamics process is studied and the first-order reaction rate equation -1n(1-a)=ktt is obtained. The effects of the reactive products, stirring speed, dosage of sulfuration agent, value of pH and sulphidizing temperature on the sulfuration of oxide ore are investigated. The results indicate that the reactive apparent activation energy is 100.8 kJ/mol and the sulfuration ratio of lead-zinc oxide ore reaches 60% under the conditions of pH 5.9-7.5, the sulfuration temperature of 130 ℃, sulfuration time of 180 min and the stirring speed of 800 r/min.
基金supported by the Human Resources Development(No.20184030202070) of the Korea Institute of Energy Technology Evaluation and Planning(KETEP) grant funded by the Korea government Ministry of Trade, Industry and Energy
文摘Development of efficient and promising bifunctional electrocatalysts for oxygen reduction and evolutionreactions is desirable. Herein, cobalt nanoparticles embedded in nitrogen and sulfur co-doped carbonnanotubes(Co@NSCNT) were prepared by a facile pyrolytic treatment. The cobalt nanoparticles and co-doping of nitrogen and sulfur can improve the electron donor-acceptor characteristics of the carbon nan-otubes and provide more active sites for catalytic oxygen reduction and evolution reactions. The preparedCo@NSCNT, annealed at 900℃, showed excellent electrocatalytic performance and better durability thancommercial platinum catalysts. Additionally, Co@NSCNT-900 catalysts exhibited comparable onset poten-tials and Tafel slopes to ruthenium oxide. Overall, Co@NSCNT showed high activity and improved dura-bility for both oxygen evolution and reduction reactions.
基金financially supported by the Hydrogenation Process and Hydrogenation Catalyst Laboratory (RIPP,SINOPEC)
文摘The effect of polycyclic aromatic hydrocarbons(PAHs)on the stability of the hydrogenation catalyst for production of ultra-low sulfur diesel was studied in a pilot plant using Ni-Mo-W/γ-Al_(2)O_(3)catalyst.The mechanisms of catalyst deactivation were analyzed by the methods of elemental analysis,nitrogen adsorption-desorption,thermogravimetry-mass spectrometry(TG-MS)technology,X-ray photoelectron spectroscopy(XPS)and high resolution transmission electron microscopy(HRTEM).The results demonstrated that PAHs had little effect on the activity of catalyst at the beginning of operation,during which the reaction temperature was increased by only 1-4℃.However,the existence of PAHs significantly accelerated the deactivation of catalyst and weakened the stability of catalyst.This phenomenon could be explained by the reason that the catalyst deactivation is not only related to the formation of carbon deposit,but is also closely related to the loss of pore volume and the decrease of Ni-W-S phase ratio after adding PAHs.
基金supported by the research fund of the National Natural Science Foundation of China (21306162)the National Basic Research Program "973" Project of China (2010CB226903)Key Laboratory for Advanced Technology in Environmental Protection of Jiangsu Province (AE201309)
文摘In this work, Zr-M(M=Cu, Mn, Ce) type sulfur transfer agent was prepared by impregnation method. Under the condition similar to that in the regenerator of FCC units, the influence of different active metal components and their contents on sulfur transfer agent were investigated. Moreover, the crystalline structure of sulfur transfer agent was characterized by X-ray diffraction(XRD) and Fourier transforms infrared spectroscopy(FT-IR). The result showed that the Zr-Mn sulfur transfer agent could effectively reduce the SO2 content in FCC regenerator flue gas, featuring high SO2 adsorption capacity. The sulfur transfer agent was inactivated in 40—60 min during the test. In the course of reduction reaction, after several reaction cycles, the formation of SO2 ceased and only H2 S was detected as the reduction product.
基金Supported by the National High Technology Research and Development Program of China(863 Project)(2015AA050504)the National Natural Science Foundation of China(21576203)
文摘The effect of boron on the performance of MoO_3/CeO_2–Al_2O_3 catalysts, which were prepared with impregnation method, was investigated. The catalysts were characterized with N_2 adsorption–desorption, XRD, H_2-TPR, and NH_3-TPD, and were tested in sulfur-resistant methanation. The results indicated that the MoO_3/CeO_2–Al_2O_3 catalysts modified by boron showed higher catalytic performance in sulfur-resistant methanation. The CO conversion increased from 47% to 62% with 0.5 wt% boron content. When the content of boron was under 0.5 wt%, the results suggested there was an increase in the amorphous form of MoO_3 caused by the generation of weak and intermediate acid sites, which had weakened the interaction between the active components and supports. While, the catalyst added 2.0 wt% boron showed the strong acid sites and the largest crystalline size resulting in the uneven distribution of ceria.
基金support provided by the National Natural Science Foundation of China(Granted No.21276276)
文摘The Mo modified Ni/Al_2O_3 catalysts were prepared and sulfided at different temperatures, and their catalytic activity for thioetherification of mercaptans and olefins(or dienes), hydrogenation of dienes and olefins in the thioetherification process using fluidized catalytic cracking(FCC) naphtha as the feedstock was investigated. In order to disclose the correlation between the physicochemical characteristics of catalysts and their catalytic activity, the surface structures and properties of the catalysts sulfided at different temperatures were characterized by the high resolution transmission electronic microscopy(HRTEM), X-ray photoelectron spectroscopy(XPS) and H2-temperature programmed reduction(H_2-TPR) technique. The results showed that an increase of sulfurization temperature not only could promote the sulfurization degree of active metals on the catalysts, but also could adjust the micro-morphology of active species. These changes could improve the catalytic performance of thioetherification, and hydrogenation of dienes and olefins. However, an excess sulfurization temperature was more easily to upgrade the ability of the catalyst for hydrogenation of olefins, which could lead to a decrease of the octane number of the product. It was also showed that a moderate sulfurization temperature not only could improve the catalytic performance of thioetherification and hydrogenation of dienes but also could control hydrogenation of olefins.
文摘Vapor-phase nitration of benzene over solid acid catalyst is expected to be a clean process with no sulfuric acid waste. We investigated this process over solid acidic catalysts utilizing diluted nitric acid (60-70%) as nitrating agent, and found that supported sulfuric acid catalyst exhibited a very high catalytic activity. Under the conditions of reaction temperature 160-170℃, space velocity (SV) 1200 h-1, the yield and the space-time yield (STY) of nitrobenzene (NB) based on HNO3 were more than 98% and 0.75 kg穔gcat-1穐-1 over 10% H2SO4/SiO2 (by weight) catalyst respectively.
基金Supported by the National Natural Science Foundation of China(51204179,51204182,51674256)The Natural Science Foundation of Jiangsu Province,China(BK20141242)
文摘CeO_2–CaO–Pd/HZSM-5 catalyst was prepared for the dimethyl ether(DME) one-step synthesis in a continuous fixed-bed micro-reactor from the sulfur-containing syngas. The catalytic stability over hybrid catalyst of CeO_2–CaO–Pd/HZSM-5 was investigated to ensure that the kinetics experimental results were not significantly influenced by induction period and catalytic deactivation. A large number of kinetic data points(40 sets) were obtained over a range of temperature(240–300 °C), pressure(3–4 MPa), gas hourly space velocity(GHSV)(2000–3000 L·kg^(-1)·h^(-1)) and H_2/CO mole ratio(2–3). Kinetic model for the methanol synthesis reaction and the dehydration of methanol were obtained separately according to reaction mechanism and Langmuir–Hinshelwood mechanism. Regression parameters were investigated by the method combining the simplex method and Runge–Kutta method. The model calculations were in appropriate accordance with the experimental data.
基金supported by the National High Technology Research and Development Program of China (No. 2009AA03Z222 and No. 2009AA05Z437)the "Six Talents Pinnacle Program" of Jiangsu Province of China (No. 2008028)
文摘Zirconia-loaded sulfuric acid (SO2-/ZrO2) catalysts were prepared by impregnation method, molded by punch tablet machine and characterized by X-ray diffraction. SO4^2-/ZrO2 catalyst was used to obtain glycerol triacetate (GTA) directly from glycerin. The effect of some factors, such as different temperatures of calcination and catalysts molded or not, on the reusable times of catalysts and the yield of GTA were investigated. The optimum reaction conditions were shown as follows: the reaction temperature was 403 K; the reaction time continued for 8 h; the amount of molded catalysts was 5 wt% of glycerin and the molar ratio of glycerin to acetic acid was 1 : 8. The yield of GTA was 97.93% under the optimum condition.
文摘Application of sulfuric acid immobilized on silica gel as an efficient and benign catalyst has been explored in the syn-thesis of 2,4,5-Triaryl-1H-imidazoles via condensation reaction of benzil or benzoin, aldehyde and ammonium acetate. The key advantages of this process are high yields, cost effectiveness of catalyst, easy work-up, purification of products by non-chromatographic method and the reusability of the H2SO4.SiO2 catalyst.
基金Supported by the National Science Fund for Excellent Young Scholars(21422607)Key Program of National Natural Science Foundation of China(91434203)
文摘A series of modifiedγ-Al_2O_3supported iron-based catalysts(M-Fe/γ-Al_2O_3)was developed to reduce SO_2in actual smelter off-gases using CO–H_2gas mixture as reducing agent for sulfur production.Used as modifiers,three metal additives—Ni,Co,and Ce were added to Fe/γ-Al_2O_3catalysts.Changes in catalyst structure and active phase were characterized with X-ray diffraction,XPS,SEM,and EDS.The reduction ability of catalysts was exhibited via CO-TPR.The prepared catalysts only need to be pre-reacted for a period of time,eliminating the need for presulfidation treatment.Reaction conditions were optimized in a fixed bed reactor to achieve high SO_2conversion and sulfur selectivity.XRD characterization was carried out to verify the resulting sulfur products.Combining in situ infrared characterization and catalyst evaluation of support and active component,the reaction mechanism was investigated and proposed.