Alcohol transformation to transportation fuel-range hydrocarbon over HZSM-5 （SIO2/A1203 = 30） catalyst was studied at 360 C and 300 psig. Product distributions and catalyst life were compared between methanol, ethan...Alcohol transformation to transportation fuel-range hydrocarbon over HZSM-5 （SIO2/A1203 = 30） catalyst was studied at 360 C and 300 psig. Product distributions and catalyst life were compared between methanol, ethanol, 1-propanol and 1-butanol as a feed. The catalyst life for 1-propanol and l-butanol was more than double compared with that for methanol and ethanol. For all the alcohols studied, the product distributions （classified to paraffin, olefin, naphthene, aromatic and naphthalene compounds） varied with time on stream （TOS）. At 24 h TOS, liquid product from 1-propanol and 1-butanol transformation primarily contains higher olefin compounds. The alcohol transformation process to higher hydrocarbon involves a complex set of reaction pathways such as dehydration, oligomerization, dehydrocyclization and hydrogenation. Compared with ethylene generated from methanol and ethanol, oligomerization of propylene and butylene has a lower activation energy and can readily take place on weaker acidic sites. On the other hand, dehydrocyclization of the oligomerized products of propylene and butylene to form the cyclic compounds requires the sites with stronger acid strength. Combination of the above mentioned reasons are the primary reasons for olefin rich product generated in the later stage of the time on stream and for the extended catalyst life time for 1-propanol and 1-butanol compared with methanol and ethanol conversion over HZSM-5.展开更多
CuCl-based catalysts are the most commonly used catalysts for the“direct synthesis”of trimethoxysilane(M3).CuCl species are sensitive to air and water,and are prone to oxidation deactivation.When CuCl is directly us...CuCl-based catalysts are the most commonly used catalysts for the“direct synthesis”of trimethoxysilane(M3).CuCl species are sensitive to air and water,and are prone to oxidation deactivation.When CuCl is directly used as a catalyst,it needs to be purified before the utilization,and the operating conditions for the catalyst preparation are relatively harsh,requiring the inert gas environment.Considering a high-temperature activation step required for CuCl-based catalysts used for catalyzing synthesis of M3 to form active phase Cu–Si alloys(Cu_(x)Si)with Si powder,in this work,a series of catalysts for the“direct synthesis”of M3 were obtained by a one-step high-temperature activation of the mixture of stable CuCl_(2) precursors,activated carbon-reducing agent,and Si powder,simultaneously achieving the reduction of CuCl_(2) to CuCl and the formation of active phase Cu_(x)Si alloys of CuCl with Si powder.The prepared samples were characterized through various characterization techniques,and investigated for the catalytic performance for the“direct synthesis”of M3.Moreover,the operation conditions were optimized,including the activation temperature,catalyst dosage,Si powder particle size,and reaction temperature.The characterization results indicate that during the one-step activation process,the CuCl_(2) precursor is reduced to CuCl,and the resulting CuCl simultaneously reacts with Si powder to form active phases Cu3Si and Cu15Si4 alloys.The optimal catalyst Sacm(250,0.8:10)exhibits a good catalytic activity with selectivity of 95%and yield of 77%for M3,and shows a good universality for various alcohol substrates.Furthermore,the catalytic mechanism of the prepared catalyst for the“direct synthesis”of M3 was discussed.展开更多
Based on the basic principle and mechanism of flue gas denitrification,the commonly used catalysts for flue gas denitrification were introduced firstly,and then the catalytic performance,stability and reaction mechani...Based on the basic principle and mechanism of flue gas denitrification,the commonly used catalysts for flue gas denitrification were introduced firstly,and then the catalytic performance,stability and reaction mechanism of catalysts in the market were analyzed.Different types of catalysts were studied to look for green catalysts with high activity,sulfur resistance,water vapor resistance and other advantages.The mechanism of denitration reaction of green catalysts was discussed,and the laws of formation,propagation and consumption of active species in the reaction process were revealed to provide theoretical basis for optimizing catalyst design and improving reaction conditions.Then the research status and problems of new catalysts for flue gas denitrification were described.Finally,the future development direction of green catalysts for flue gas denitration was discussed to improve the performance and stability of catalysts and meet the performance requirements of denitration catalysts in different industries.展开更多
Polycrystalline SnO2 fine powder consisting of nano-particles （SnO2-NP）, SnO2 nano-sheets （SnO2-NS）, and SnO2 containing both nano-rods and nano-particles （SnO2-NR＋NP） were prepared and used for CO oxidation. S...Polycrystalline SnO2 fine powder consisting of nano-particles （SnO2-NP）, SnO2 nano-sheets （SnO2-NS）, and SnO2 containing both nano-rods and nano-particles （SnO2-NR＋NP） were prepared and used for CO oxidation. SnO2-NS possesses a mesoporous structure and has a higher surface area, larger pore volume, and more active species than SnO2-NP, and shows improved activity. In contrast, although SnO2-NR＋NP has only a slightly higher surface area and pore volume, and slightly more active surface oxygen species than SnO2-NP, it has more exposed active （110） facets, which is the reason for its improved oxidation activity. Water vapor has only a reversible and weak influence on SnO2-NS, therefore it is a potential catalyst for emission control processes.展开更多
A variety of spherical and structured activated charcoal supported Pt/Fe3O4 composites with an average particle size of ~100 nm have been synthesized by a self-assembly method using the difference of reduction potenti...A variety of spherical and structured activated charcoal supported Pt/Fe3O4 composites with an average particle size of ~100 nm have been synthesized by a self-assembly method using the difference of reduction potential between Pt （Ⅳ） and Fe （Ⅱ） precursors as driving force. The formed Fe3O4 nanoparticles （NPs） effectively prevent the aggregation of Pt nanocrystallites and promote the dispersion of Pt NPs on the surface of catalyst, which will be favorable for the exposure of Pt active sites for high-efficient adsorption and contact of substrate and hydrogen donor. The electron-enrichment state of Pt NPs donated by Fe304 nanocrystallites is corroborated by XPS measurement, which is responsible for promoting and activating the terminal C=O bond of adsorbed substrate via a vertical configuration. The experimental results show that the activated charcoal supported Pt/Fe3O4 catalyst exhibits 94.8% selectivity towards cinnamyl alcohol by the transfer hydrogenation of einnamaldehyde with Pt loading of 2.46% under the optimum conditions of 120 ℃ for 6 h, and 2-propanol as a hydrogen donor. Additionally, the present study demonstrates that a high-efficient and recyclable catalyst can be rapidly separated from the mixture due to its natural magnetism upon the application of magnetic field.展开更多
To discuss the potential role of iridium(Ir)nanoparticles loaded under atmospheric and high pressures,we prepared a series of cata-lysts with the same active phase but different contents of 10wt%,20wt%,and 30wt%on gam...To discuss the potential role of iridium(Ir)nanoparticles loaded under atmospheric and high pressures,we prepared a series of cata-lysts with the same active phase but different contents of 10wt%,20wt%,and 30wt%on gamma-alumina for decomposition of hydrazine.Un-der atmospheric pressure,the performance of the catalyst was better when 30wt%of the Ir nanoparticles was used with chelating agent that had greater selectivity of approximately 27%.The increase in the reaction rate from 175 to 220 h^(−1)at higher Ir loading(30wt%)was due to a good dispersion of high-number active phases rather than an agglomeration surface.As a satisfactory result of this investigation at high pressure,Ir catalysts with different weight percentages showed the same stability against crushing and activity with a characteristic velocity of approxim-ately 1300 m/s.展开更多
The dehydroaramatization of methane over W-supported ZSM-5 with varying degrees of Li+ ion-exchanged catalysts was studied with and without oxygen at 1073 K and atmospheric pressure. Catalyst activity and stability we...The dehydroaramatization of methane over W-supported ZSM-5 with varying degrees of Li+ ion-exchanged catalysts was studied with and without oxygen at 1073 K and atmospheric pressure. Catalyst activity and stability were found to be influenced by the catalyst acidity related to Bronsted acid sites and by the presence of oxygen in the feed. The NH3-TPD and FTIR-pyridine results demonstrated that partially exchanged of H+ ions by Li+ into the W/HZSM-5 catalysts could be used to control the amount of strong acid sites on the catalyst surface. Without oxygen, the 3WHLi-Z (5:1) catalyst that has strong acid sites equal to nearly 74% of the original strong acid sites in the parent HZSM-5 exhibited the highest methane conversion and selectivity towards aromatics. However, the catalyst deactivated in a five hour period. In the presence of oxygen, the catalyst activity and stability could be improved further. The results of this study revealed that a suitable amount of strong Bronsted acid sites as well as oxygen addition in the feed increased the catalyst activity and stability. The 3WHLi-Z(5:1) catalyst exhibited improved performance in the dehydroaromatization of methane.展开更多
The possibility and feasibility of using supercritical fluid СО<sub>2</sub> extraction process have been investigated and described in the book as part of the task of spent catalysts regeneration. The an...The possibility and feasibility of using supercritical fluid СО<sub>2</sub> extraction process have been investigated and described in the book as part of the task of spent catalysts regeneration. The analysis of deactivating compounds has been carried out for industrial catalysts such as: 1) palladium catalyst G-58E of ethane-ethylene fraction hydrogenation;2) nickel/kieselguhr catalyst of process of separating acetylenic compounds from isoprene;3) active aluminum oxide catalyst of methyl phenyl carbinol dehydration process;4) palladium catalyst LD-265 of hydrocarbons hydrogenation process;5) nickel-molybdenum catalysts DN-3531 and Criterion 514 of kerosene hydrotreating process. The results of the study of catalyst deactivating compounds solubility in pure supercritical carbon dioxide and supercritical carbon dioxide are modified with polar additive. The results of the solubility study are described using the Peng-Robinson equation of state. The results of the implementation of the supercritical fluid СО<sub>2</sub> extraction process with respect to deactivated industrial catalyst samples have been provided. A comparison of the characteristics of samples of catalysts regenerated using the traditional approach and the SC-CO<sub>2</sub> extraction process has been conducted. The possibility of using supercritical fluid CO<sub>2</sub> impregnation process in the synthesis of a palladium catalyst has been investigated. The synthesis of palladium chloride-based organometallic complexes has been carried out. The results of the study of solubility thereof in supercritical carbon dioxide have been provided. A dynamic supercritical fluid CO<sub>2</sub> impregnation process condition has been implemented. A comparison of the characteristics of palladium catalyst samples synthesized using the conventional approach and SC-CO<sub>2</sub> impregnation process has been conducted and presented in the book.展开更多
As a potential methane efficient conversion process,non-oxidative aromatization of methane in fluidized bed requires a catalyst with good attrition resistance,especially in the states of high temperature,longtime rapi...As a potential methane efficient conversion process,non-oxidative aromatization of methane in fluidized bed requires a catalyst with good attrition resistance,especially in the states of high temperature,longtime rapid movement and chemical reaction.Existing evaluation methods for attrition resistance,such as ASTM D5757 and Jet Cup test,are targeted for fresh catalysts at ambient temperature,which cannot well reflect the real process.In this study,spherical-shaped Mo/HZSM-5 catalyst prepared by dipping and spray drying was placed in a self-made apparatus for attrition testing,in which the catalyst attrition under different system temperatures,running time and process factors was investigated with percent mass loss(PML),particle size-mass distribution(PSMD)and scanning electron microscope(SEM).Carbon deposition on the catalyst before and after activation,aromatization and regeneration was analyzed by thermogravimetry(TG),and the attrited catalysts were evaluated for methane dehydro-aromatization(MDA).The results show that the surface abrasion and body breakage of catalyst particles occur continuously,with the increase of system temperature and running time,and make the PML rise gradually.The process factors of activation,aromatization and regeneration can cause the catalyst attrition and carbon deposits,which broaden the PSMD in varying degrees,and the carbon-substances on catalysts greatly improve their attrition resistance at high temperature.Catalyst attrition has a certain influence on its catalytic performance,and the main reasons point to particle breakage and fine powder escape.展开更多
The main problem in an efficient Zn（CH3COO）2/AC （AC-activated carbon） catalyst preparation is the achievement of uniform distribution of highly dispersed salt component on the activated carbon （AC） surface. The ...The main problem in an efficient Zn（CH3COO）2/AC （AC-activated carbon） catalyst preparation is the achievement of uniform distribution of highly dispersed salt component on the activated carbon （AC） surface. The solution of this problem is modification of the AC by hydrogen peroxide （H202） oxidation of the surface and treatment of AC with acetic acid as well as special methods of salt deposition and catalyst drying. The investigations of these ways of AC surface modification （treatment of AC with acetic acid and H2O2） have demonstrated the obtained AC to have both an increased adsorption capacity as to Zn（OAc）2 and optimum volumes of meso- and micro-pores as well as high catalyst activity in vinyl acetate （VA） synthesis. The characteristics of supports and catalysts were found out by benzene, water and acetic acid vapors adsorption. The distribution of the salt on the AC surface was studied by small-angle X-ray scattering （SAXS）, by scanning electron microscopy （SEM） and X-ray micro-analysis （XMA）. The catalysts were tested in vinyl acetate synthesis in flow-bed isothermal reactor by cyclic method at 175, 205 and 230℃.展开更多
Reductive pretreatment is an important step for activating supported metal catalysts but has received little attention.In this study,reconstruction of the supported nickel catalyst was found to be sensitive to pretrea...Reductive pretreatment is an important step for activating supported metal catalysts but has received little attention.In this study,reconstruction of the supported nickel catalyst was found to be sensitive to pretreatment conditions.In contrast to the traditional activation procedure in hydrogen,activating the catalyst in syngas created supported Ni nanoparticles with a polycrystalline structure containing an abundance of grain boundaries.The unique post-activation catalyst structure offered enhanced CO adsorption and an improved CO methanation rate.The current strategy to tune the catalyst structure via manipulating the activation conditions can potentially guide the rational design of other supported metal catalysts.展开更多
Co-precipitation method was selected for the preparation of Ni/Al_2O_3, Ni/ZrO_2 and Ni/CeO_2 catalysts, and their performances in methanation were investigated in this study. The structure and surface properties of t...Co-precipitation method was selected for the preparation of Ni/Al_2O_3, Ni/ZrO_2 and Ni/CeO_2 catalysts, and their performances in methanation were investigated in this study. The structure and surface properties of these catalysts were characterized by BET, XRD, H_2-TPD, TEM and H_2-TPR. The results showed that the catalytic activity at low temperature followed the order: Ni/Al_2O_3>Ni/ZrO_2>Ni/CeO_2. Ni/Al_2O_3 catalyst presented the best catalytic performance with the highest CH_4 selectivity of 94.5%. The characterization results indicated that the dispersion of the active component Ni was the main factor affecting the catalytic activity and the one with higher dispersion gave better performance.展开更多
A series of catalysts with (Ce-Zr-La-Pr)O contents range from 0 to 50% in coating and single-palladium loads on substrates were prepared to study effects of (Ce-Zr-La-Pr)O contents on catalytic activities and durabili...A series of catalysts with (Ce-Zr-La-Pr)O contents range from 0 to 50% in coating and single-palladium loads on substrates were prepared to study effects of (Ce-Zr-La-Pr)O contents on catalytic activities and durability by contrasting the characteristics of light-off, A/F and catalytic conversions of the fresh catalysts with that of the aged catalysts. The results show that (Ce-Zr-La-Pr)O can enhance the catalysts light-off characteristics, widen A/F windows and increase catalytic conversions at a certain extent through optimizing physical structural and chemical property of the mixed coating. However, (Ce-Zr-La-Pr)O contents influence greatly on the catalysts activities and durability, and the catalysts with contents ranging from 10% to 30% exhibited better integrative properties in all samples, and 10% was the optical content to make the catalyst performance highest in this thesis. It is indicated that an suitable content of (Ce-Zr-La-Pr)O plays an important role in assisting catalysis, enhancing durability and increasing oxygen storage capability.展开更多
Mercury-containing catalysts are widely used for acetylene hydrochlorination in China. Surface chemical characteristics of the fresh low-level mercury catalysts and spent low-level mercury catalysts were compared usin...Mercury-containing catalysts are widely used for acetylene hydrochlorination in China. Surface chemical characteristics of the fresh low-level mercury catalysts and spent low-level mercury catalysts were compared using multiple characterization methods. Pore blockage and active site coverage caused by chlorine-containing organics are responsible for catalyst deactivation. The reactions of chloroethylene and acetylene with chlorine free radical can generate chlorine-containing organic species. SiO_2 and functional groups on activated carbon contribute to the generation of carbon deposition. No significant reduction in the total content of mercury was observed after catalyst deactivation, while there was mercury loss locally. The irreversible loss of HgCl_2 caused by volatilization, reduction and poisoning of elements S and P also can lead to catalyst deactivation. Si, Al, Ca and Fe oxides are scattered on the activated carbon. Active components are still uniformly absorbed on activated carbon after catalyst deactivation.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
Isothermal effectiveness factors for slab,cylinder and sphere shaped catalysts with uniform or nonuni-form intrinsic activity profiles have been investigated.In the case of zero-,first- and second-order kinetics,the e...Isothermal effectiveness factors for slab,cylinder and sphere shaped catalysts with uniform or nonuni-form intrinsic activity profiles have been investigated.In the case of zero-,first- and second-order kinetics,the effectiveness factors of pellets with increasing activity towards the pellet surface are larger than that ofuniform active catalyst,and they are proportional to the square root of the activity at the pellet surfacewith significant diffusion effect.The effectiveness factor-Thiele modulus curves which are valid for bothuniform and nonuniform catalysts have been obtained with the Thiele modulus modified by equivalent thick-hess of effective layer of the catalyst.Thus,the effectiveness factor for nonuniform active catalyst could bepredicted with a maximun deviation of 5% in the case of significant or insignificant diffusion effect but 10%in general.展开更多
A new carbonaceous catalyst with sulfonic acid group （-SO3H） was prepared by incomplete carbonization of β-cyclodextrin followed by sulfonation.The sulfonated amorphous carbon was characterized by IR,elemental anal...A new carbonaceous catalyst with sulfonic acid group （-SO3H） was prepared by incomplete carbonization of β-cyclodextrin followed by sulfonation.The sulfonated amorphous carbon was characterized by IR,elemental analysis,DSC-TGA and PXRD,and the catalytic activity was investigated to be an efficient catalyst for the esterification reactions with maximum yield of 87%.The sulfonated carbonaceous catalyst was readily separated from the reaction solution and keeps approximately equal catalytic activity.The results confirm that the active centre is the hydrophilic sulfonic acid functional group in the esterification reactions.展开更多
基金the Pacific Northwest National Laboratory's Laboratory Directed Research and Development Funding
文摘Alcohol transformation to transportation fuel-range hydrocarbon over HZSM-5 （SIO2/A1203 = 30） catalyst was studied at 360 C and 300 psig. Product distributions and catalyst life were compared between methanol, ethanol, 1-propanol and 1-butanol as a feed. The catalyst life for 1-propanol and l-butanol was more than double compared with that for methanol and ethanol. For all the alcohols studied, the product distributions （classified to paraffin, olefin, naphthene, aromatic and naphthalene compounds） varied with time on stream （TOS）. At 24 h TOS, liquid product from 1-propanol and 1-butanol transformation primarily contains higher olefin compounds. The alcohol transformation process to higher hydrocarbon involves a complex set of reaction pathways such as dehydration, oligomerization, dehydrocyclization and hydrogenation. Compared with ethylene generated from methanol and ethanol, oligomerization of propylene and butylene has a lower activation energy and can readily take place on weaker acidic sites. On the other hand, dehydrocyclization of the oligomerized products of propylene and butylene to form the cyclic compounds requires the sites with stronger acid strength. Combination of the above mentioned reasons are the primary reasons for olefin rich product generated in the later stage of the time on stream and for the extended catalyst life time for 1-propanol and 1-butanol compared with methanol and ethanol conversion over HZSM-5.
基金supported by the Key Research & Development Plan of Shandong Province (the Major Scientific and Technological Innovation Projects, 2021ZDSYS13)the Natural Science Foundation of Shandong Province (ZR2021MB135)
文摘CuCl-based catalysts are the most commonly used catalysts for the“direct synthesis”of trimethoxysilane(M3).CuCl species are sensitive to air and water,and are prone to oxidation deactivation.When CuCl is directly used as a catalyst,it needs to be purified before the utilization,and the operating conditions for the catalyst preparation are relatively harsh,requiring the inert gas environment.Considering a high-temperature activation step required for CuCl-based catalysts used for catalyzing synthesis of M3 to form active phase Cu–Si alloys(Cu_(x)Si)with Si powder,in this work,a series of catalysts for the“direct synthesis”of M3 were obtained by a one-step high-temperature activation of the mixture of stable CuCl_(2) precursors,activated carbon-reducing agent,and Si powder,simultaneously achieving the reduction of CuCl_(2) to CuCl and the formation of active phase Cu_(x)Si alloys of CuCl with Si powder.The prepared samples were characterized through various characterization techniques,and investigated for the catalytic performance for the“direct synthesis”of M3.Moreover,the operation conditions were optimized,including the activation temperature,catalyst dosage,Si powder particle size,and reaction temperature.The characterization results indicate that during the one-step activation process,the CuCl_(2) precursor is reduced to CuCl,and the resulting CuCl simultaneously reacts with Si powder to form active phases Cu3Si and Cu15Si4 alloys.The optimal catalyst Sacm(250,0.8:10)exhibits a good catalytic activity with selectivity of 95%and yield of 77%for M3,and shows a good universality for various alcohol substrates.Furthermore,the catalytic mechanism of the prepared catalyst for the“direct synthesis”of M3 was discussed.
基金Supported by the Interdisciplinary Team Project of Shenyang University of Technology in 2021:Green and Low-carbon(Technology and Evaluation)of Typical Industries of Carbon Peak(2021-70-06)"Double First-class"Construction Project of Liaoning Province in 2020(Scientific Research)(FWDFGD2020041).
文摘Based on the basic principle and mechanism of flue gas denitrification,the commonly used catalysts for flue gas denitrification were introduced firstly,and then the catalytic performance,stability and reaction mechanism of catalysts in the market were analyzed.Different types of catalysts were studied to look for green catalysts with high activity,sulfur resistance,water vapor resistance and other advantages.The mechanism of denitration reaction of green catalysts was discussed,and the laws of formation,propagation and consumption of active species in the reaction process were revealed to provide theoretical basis for optimizing catalyst design and improving reaction conditions.Then the research status and problems of new catalysts for flue gas denitrification were described.Finally,the future development direction of green catalysts for flue gas denitration was discussed to improve the performance and stability of catalysts and meet the performance requirements of denitration catalysts in different industries.
基金supported by the Ministry of Science and Technology of China(Nos.2016YFA0204100 and 2016YFA0200200)the National Natural Science Foundation of China(Nos.21321002,21573220 and 21303191)the strategic Priority Research Program of the Chinese Academy of Sciences(No.XDA09030100)
基金supported by the Cultivation Project of Major Achievements Transformation of Sichuan Provincial Education Department(#14CZ0005)supported by the Natural Science Foundation of China(#21406184)
基金supported by the National Natural Science Foundation of China (21263015)the Education Department of Jiangxi Province (KJLD14005)the Natural Science Foundation of Jiangxi Province(20151BBE50006,20122BAB203009)~~
文摘Polycrystalline SnO2 fine powder consisting of nano-particles （SnO2-NP）, SnO2 nano-sheets （SnO2-NS）, and SnO2 containing both nano-rods and nano-particles （SnO2-NR＋NP） were prepared and used for CO oxidation. SnO2-NS possesses a mesoporous structure and has a higher surface area, larger pore volume, and more active species than SnO2-NP, and shows improved activity. In contrast, although SnO2-NR＋NP has only a slightly higher surface area and pore volume, and slightly more active surface oxygen species than SnO2-NP, it has more exposed active （110） facets, which is the reason for its improved oxidation activity. Water vapor has only a reversible and weak influence on SnO2-NS, therefore it is a potential catalyst for emission control processes.
基金This work is supported by the National Natural Science Foundation of China （No.51372248, No.51432009 and No.51502297）, Instrument Developing Project of the Chinese Academy of Sciences （No.yz201421）, the CAS/SAFEA International Partnership Program for Creative Research Teams of Chinese Academy of Sciences, China.
文摘A variety of spherical and structured activated charcoal supported Pt/Fe3O4 composites with an average particle size of ~100 nm have been synthesized by a self-assembly method using the difference of reduction potential between Pt （Ⅳ） and Fe （Ⅱ） precursors as driving force. The formed Fe3O4 nanoparticles （NPs） effectively prevent the aggregation of Pt nanocrystallites and promote the dispersion of Pt NPs on the surface of catalyst, which will be favorable for the exposure of Pt active sites for high-efficient adsorption and contact of substrate and hydrogen donor. The electron-enrichment state of Pt NPs donated by Fe304 nanocrystallites is corroborated by XPS measurement, which is responsible for promoting and activating the terminal C=O bond of adsorbed substrate via a vertical configuration. The experimental results show that the activated charcoal supported Pt/Fe3O4 catalyst exhibits 94.8% selectivity towards cinnamyl alcohol by the transfer hydrogenation of einnamaldehyde with Pt loading of 2.46% under the optimum conditions of 120 ℃ for 6 h, and 2-propanol as a hydrogen donor. Additionally, the present study demonstrates that a high-efficient and recyclable catalyst can be rapidly separated from the mixture due to its natural magnetism upon the application of magnetic field.
文摘To discuss the potential role of iridium(Ir)nanoparticles loaded under atmospheric and high pressures,we prepared a series of cata-lysts with the same active phase but different contents of 10wt%,20wt%,and 30wt%on gamma-alumina for decomposition of hydrazine.Un-der atmospheric pressure,the performance of the catalyst was better when 30wt%of the Ir nanoparticles was used with chelating agent that had greater selectivity of approximately 27%.The increase in the reaction rate from 175 to 220 h^(−1)at higher Ir loading(30wt%)was due to a good dispersion of high-number active phases rather than an agglomeration surface.As a satisfactory result of this investigation at high pressure,Ir catalysts with different weight percentages showed the same stability against crushing and activity with a characteristic velocity of approxim-ately 1300 m/s.
文摘The dehydroaramatization of methane over W-supported ZSM-5 with varying degrees of Li+ ion-exchanged catalysts was studied with and without oxygen at 1073 K and atmospheric pressure. Catalyst activity and stability were found to be influenced by the catalyst acidity related to Bronsted acid sites and by the presence of oxygen in the feed. The NH3-TPD and FTIR-pyridine results demonstrated that partially exchanged of H+ ions by Li+ into the W/HZSM-5 catalysts could be used to control the amount of strong acid sites on the catalyst surface. Without oxygen, the 3WHLi-Z (5:1) catalyst that has strong acid sites equal to nearly 74% of the original strong acid sites in the parent HZSM-5 exhibited the highest methane conversion and selectivity towards aromatics. However, the catalyst deactivated in a five hour period. In the presence of oxygen, the catalyst activity and stability could be improved further. The results of this study revealed that a suitable amount of strong Bronsted acid sites as well as oxygen addition in the feed increased the catalyst activity and stability. The 3WHLi-Z(5:1) catalyst exhibited improved performance in the dehydroaromatization of methane.
基金sponsored by the National Basic Research Program of China(973 Program)under grant no.2015CB351905the National Natural Science Foundation of China(no.61504019)+3 种基金China Postdoctoral Science Foundation(no.2015M580783)Scientific Research Start-up Foundation of University of Electronic Science and Technology of China(Y02002010301082)the Technology Innovative Research Team of Sichuan Province of China(no.2015TD0005)the Fundamental Research Funds for the Central Universities of China(no.ZYGX2015J140)
文摘The possibility and feasibility of using supercritical fluid СО<sub>2</sub> extraction process have been investigated and described in the book as part of the task of spent catalysts regeneration. The analysis of deactivating compounds has been carried out for industrial catalysts such as: 1) palladium catalyst G-58E of ethane-ethylene fraction hydrogenation;2) nickel/kieselguhr catalyst of process of separating acetylenic compounds from isoprene;3) active aluminum oxide catalyst of methyl phenyl carbinol dehydration process;4) palladium catalyst LD-265 of hydrocarbons hydrogenation process;5) nickel-molybdenum catalysts DN-3531 and Criterion 514 of kerosene hydrotreating process. The results of the study of catalyst deactivating compounds solubility in pure supercritical carbon dioxide and supercritical carbon dioxide are modified with polar additive. The results of the solubility study are described using the Peng-Robinson equation of state. The results of the implementation of the supercritical fluid СО<sub>2</sub> extraction process with respect to deactivated industrial catalyst samples have been provided. A comparison of the characteristics of samples of catalysts regenerated using the traditional approach and the SC-CO<sub>2</sub> extraction process has been conducted. The possibility of using supercritical fluid CO<sub>2</sub> impregnation process in the synthesis of a palladium catalyst has been investigated. The synthesis of palladium chloride-based organometallic complexes has been carried out. The results of the study of solubility thereof in supercritical carbon dioxide have been provided. A dynamic supercritical fluid CO<sub>2</sub> impregnation process condition has been implemented. A comparison of the characteristics of palladium catalyst samples synthesized using the conventional approach and SC-CO<sub>2</sub> impregnation process has been conducted and presented in the book.
基金supported by Hydrocarbon High-efficiency Utilization Technology Research Center of Shaanxi Yanchang Petroleum(Group)Co.,Ltd.,China(Contract No.HCRC-C13-010)the National Natural Science Foundation of China(No.21536009)。
文摘As a potential methane efficient conversion process,non-oxidative aromatization of methane in fluidized bed requires a catalyst with good attrition resistance,especially in the states of high temperature,longtime rapid movement and chemical reaction.Existing evaluation methods for attrition resistance,such as ASTM D5757 and Jet Cup test,are targeted for fresh catalysts at ambient temperature,which cannot well reflect the real process.In this study,spherical-shaped Mo/HZSM-5 catalyst prepared by dipping and spray drying was placed in a self-made apparatus for attrition testing,in which the catalyst attrition under different system temperatures,running time and process factors was investigated with percent mass loss(PML),particle size-mass distribution(PSMD)and scanning electron microscope(SEM).Carbon deposition on the catalyst before and after activation,aromatization and regeneration was analyzed by thermogravimetry(TG),and the attrited catalysts were evaluated for methane dehydro-aromatization(MDA).The results show that the surface abrasion and body breakage of catalyst particles occur continuously,with the increase of system temperature and running time,and make the PML rise gradually.The process factors of activation,aromatization and regeneration can cause the catalyst attrition and carbon deposits,which broaden the PSMD in varying degrees,and the carbon-substances on catalysts greatly improve their attrition resistance at high temperature.Catalyst attrition has a certain influence on its catalytic performance,and the main reasons point to particle breakage and fine powder escape.
文摘The main problem in an efficient Zn（CH3COO）2/AC （AC-activated carbon） catalyst preparation is the achievement of uniform distribution of highly dispersed salt component on the activated carbon （AC） surface. The solution of this problem is modification of the AC by hydrogen peroxide （H202） oxidation of the surface and treatment of AC with acetic acid as well as special methods of salt deposition and catalyst drying. The investigations of these ways of AC surface modification （treatment of AC with acetic acid and H2O2） have demonstrated the obtained AC to have both an increased adsorption capacity as to Zn（OAc）2 and optimum volumes of meso- and micro-pores as well as high catalyst activity in vinyl acetate （VA） synthesis. The characteristics of supports and catalysts were found out by benzene, water and acetic acid vapors adsorption. The distribution of the salt on the AC surface was studied by small-angle X-ray scattering （SAXS）, by scanning electron microscopy （SEM） and X-ray micro-analysis （XMA）. The catalysts were tested in vinyl acetate synthesis in flow-bed isothermal reactor by cyclic method at 175, 205 and 230℃.
基金sponsored by the National Natural Science Foundation of China (22078089 and 22122807)Natural Science Foundation of Shanghai (21ZR1425700)+1 种基金Program for Professor of Special Appointment (Eastern Scholar) at Shanghai Institutions of Higher Learning and Shanghai Sailing Program (19YF1410600)The research at Lehigh University was supported by the Center for Understanding and Control of Acid Gas-Induced Evolution of Materials for Energy (UNCAGE-ME), an Energy Frontier Research Center funded by Department of Energy, Office of Science, Office of Basic Energy Sciences (DE-SC0012577)
文摘Reductive pretreatment is an important step for activating supported metal catalysts but has received little attention.In this study,reconstruction of the supported nickel catalyst was found to be sensitive to pretreatment conditions.In contrast to the traditional activation procedure in hydrogen,activating the catalyst in syngas created supported Ni nanoparticles with a polycrystalline structure containing an abundance of grain boundaries.The unique post-activation catalyst structure offered enhanced CO adsorption and an improved CO methanation rate.The current strategy to tune the catalyst structure via manipulating the activation conditions can potentially guide the rational design of other supported metal catalysts.
基金financial support from the National Science and Technology Supporting Plan through contract (2015BAD15B06)the National Natural Science Foundation of China (51661145011)
文摘Co-precipitation method was selected for the preparation of Ni/Al_2O_3, Ni/ZrO_2 and Ni/CeO_2 catalysts, and their performances in methanation were investigated in this study. The structure and surface properties of these catalysts were characterized by BET, XRD, H_2-TPD, TEM and H_2-TPR. The results showed that the catalytic activity at low temperature followed the order: Ni/Al_2O_3>Ni/ZrO_2>Ni/CeO_2. Ni/Al_2O_3 catalyst presented the best catalytic performance with the highest CH_4 selectivity of 94.5%. The characterization results indicated that the dispersion of the active component Ni was the main factor affecting the catalytic activity and the one with higher dispersion gave better performance.
文摘A series of catalysts with (Ce-Zr-La-Pr)O contents range from 0 to 50% in coating and single-palladium loads on substrates were prepared to study effects of (Ce-Zr-La-Pr)O contents on catalytic activities and durability by contrasting the characteristics of light-off, A/F and catalytic conversions of the fresh catalysts with that of the aged catalysts. The results show that (Ce-Zr-La-Pr)O can enhance the catalysts light-off characteristics, widen A/F windows and increase catalytic conversions at a certain extent through optimizing physical structural and chemical property of the mixed coating. However, (Ce-Zr-La-Pr)O contents influence greatly on the catalysts activities and durability, and the catalysts with contents ranging from 10% to 30% exhibited better integrative properties in all samples, and 10% was the optical content to make the catalyst performance highest in this thesis. It is indicated that an suitable content of (Ce-Zr-La-Pr)O plays an important role in assisting catalysis, enhancing durability and increasing oxygen storage capability.
基金Supported by the National Science Fund for Excellent Young Scholars of China(No.51522405)
文摘Mercury-containing catalysts are widely used for acetylene hydrochlorination in China. Surface chemical characteristics of the fresh low-level mercury catalysts and spent low-level mercury catalysts were compared using multiple characterization methods. Pore blockage and active site coverage caused by chlorine-containing organics are responsible for catalyst deactivation. The reactions of chloroethylene and acetylene with chlorine free radical can generate chlorine-containing organic species. SiO_2 and functional groups on activated carbon contribute to the generation of carbon deposition. No significant reduction in the total content of mercury was observed after catalyst deactivation, while there was mercury loss locally. The irreversible loss of HgCl_2 caused by volatilization, reduction and poisoning of elements S and P also can lead to catalyst deactivation. Si, Al, Ca and Fe oxides are scattered on the activated carbon. Active components are still uniformly absorbed on activated carbon after catalyst deactivation.
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Isothermal effectiveness factors for slab,cylinder and sphere shaped catalysts with uniform or nonuni-form intrinsic activity profiles have been investigated.In the case of zero-,first- and second-order kinetics,the effectiveness factors of pellets with increasing activity towards the pellet surface are larger than that ofuniform active catalyst,and they are proportional to the square root of the activity at the pellet surfacewith significant diffusion effect.The effectiveness factor-Thiele modulus curves which are valid for bothuniform and nonuniform catalysts have been obtained with the Thiele modulus modified by equivalent thick-hess of effective layer of the catalyst.Thus,the effectiveness factor for nonuniform active catalyst could bepredicted with a maximun deviation of 5% in the case of significant or insignificant diffusion effect but 10%in general.
基金Funded by the Guangdong Science Project (No.2008B011000015)
文摘A new carbonaceous catalyst with sulfonic acid group （-SO3H） was prepared by incomplete carbonization of β-cyclodextrin followed by sulfonation.The sulfonated amorphous carbon was characterized by IR,elemental analysis,DSC-TGA and PXRD,and the catalytic activity was investigated to be an efficient catalyst for the esterification reactions with maximum yield of 87%.The sulfonated carbonaceous catalyst was readily separated from the reaction solution and keeps approximately equal catalytic activity.The results confirm that the active centre is the hydrophilic sulfonic acid functional group in the esterification reactions.
