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
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 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
The performance of the two newly developed bimetallic catalysts based on the precursor, Mo/Al_2O_3, was compared for reverse water gas shift(RWGS) reaction. The structures of the precursor and the catalysts were studi...The performance of the two newly developed bimetallic catalysts based on the precursor, Mo/Al_2O_3, was compared for reverse water gas shift(RWGS) reaction. The structures of the precursor and the catalysts were studied using X-ray diffraction(XRD), Brunauer–Emmett–Teller(BET) analysis, inductively coupled plasma-atomic emission spectrometry(ICP-AES), CO chemisorption, temperature programmed reduction of hydrogen(H_2-TPR) and scanning electron microscopy(SEM) techniques. The activity of Fe-Mo and Co-Mo catalysts was compared in a fixed bed reactor at different temperatures. It is shown that the Co-Mo catalyst has higher CO_2 conversion at all temperature level. The time-on-stream(TOS) analysis of the activity of catalysts for the RWGS reaction was carried out over a continuous period of 60h for both catalysts. The Fe-Mo/Al_2O_3 catalyst exhibits good stability within a period of 60h, however, the Co-Mo/Al_2O_3 is gradually deactivated after 50h of reaction time. Existence of(Fe_2(MoO4_))_3 phase in Fe-Mo/Al_2O_3 catalyst makes this catalyst more stable for RWGS reaction.展开更多
Oxygen evolution reaction（OER） is one of the most important reactions in the energy storage devices such as metal–air batteries and unitized regenerative fuel cells（URFCs）. However, the kinetically sluggishness o...Oxygen evolution reaction（OER） is one of the most important reactions in the energy storage devices such as metal–air batteries and unitized regenerative fuel cells（URFCs）. However, the kinetically sluggishness of OER and the high prices as well as the scarcity of the most active precious metal electrocatalysts are the major bottleneck in these devices. Developing low-cost non-precious metal catalysts with high activity and stability for OER is highly desirable. A facile, in situ template method combining the dodecyl benzene sulfuric acid sodium（SDBS） assisted hydrothermal process with subsequent high-temperature treatment was developed to prepare porous Co3O4 with improved surface area and hierarchical porous structure as precious catalysts alternative for oxygen evolution reaction（OER）. Due to the unique structure, the as-prepared catalyst shows higher electrocatalytic activity than Co3O4 prepared by traditional thermal-decomposition method（noted as Co3O4-T） and commercial IrO2 catalyst for OER in 0.1M KOH aqueous solution. Moreover, it displays improved stability than Co3O4-T. The results demonstrate a highly efficient, scalable, and low cost method for developing highly active and stable OER electrocatalysts in alkaline solutions.展开更多
Activated carbon （AC） supported silver catalysts were prepared by incipient wetness impregnation method and their catalytic performance for CO preferential oxidation （PROX） in excess H2 was evaluated. Ag/AC cataly...Activated carbon （AC） supported silver catalysts were prepared by incipient wetness impregnation method and their catalytic performance for CO preferential oxidation （PROX） in excess H2 was evaluated. Ag/AC catalysts, after reduction in H2 at low temperatures （≤200 ℃） following heat treatment in He at 200 ℃ （He200H200）, exhibited the best catalytic properties. Temperature-programmed desorption （TPD）, X-ray diffraction （XRD） and temperature-programmed reduction （TPR） results indicated that silver oxides were produced during heat treatment in He at 200 ℃ which were reduced to metal silver nanoparticles in H2 at low temperatures （≤200 ℃）, simultaneously generating the adsorbed water/OH. CO conversion was enhanced 40% after water treatment following heat treatment in He at 600 ℃. These results imply that the metal silver nanoparticles are the active species and the adsorbed water/OH has noticeable promotion effects on CO oxidation. However, the promotion effect is still limited compared to gold catalysts under the similar conditions, which may be the reason of low selectivity to CO oxidation in PROX over silver catalysts. The reported Ag/AC-S-He catalyst after He200H200 treatment displayed similar PROX of CO reaction properties to Ag/SiO2. This means that Ag/AC catalyst is also an efficient low-temperature CO oxidation catalyst.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 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)
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)
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.
基金the Iranian Nano Technology Initiative Council and the Petroleum University of Technology for financial support
文摘The performance of the two newly developed bimetallic catalysts based on the precursor, Mo/Al_2O_3, was compared for reverse water gas shift(RWGS) reaction. The structures of the precursor and the catalysts were studied using X-ray diffraction(XRD), Brunauer–Emmett–Teller(BET) analysis, inductively coupled plasma-atomic emission spectrometry(ICP-AES), CO chemisorption, temperature programmed reduction of hydrogen(H_2-TPR) and scanning electron microscopy(SEM) techniques. The activity of Fe-Mo and Co-Mo catalysts was compared in a fixed bed reactor at different temperatures. It is shown that the Co-Mo catalyst has higher CO_2 conversion at all temperature level. The time-on-stream(TOS) analysis of the activity of catalysts for the RWGS reaction was carried out over a continuous period of 60h for both catalysts. The Fe-Mo/Al_2O_3 catalyst exhibits good stability within a period of 60h, however, the Co-Mo/Al_2O_3 is gradually deactivated after 50h of reaction time. Existence of(Fe_2(MoO4_))_3 phase in Fe-Mo/Al_2O_3 catalyst makes this catalyst more stable for RWGS reaction.
基金supported by the Youth Innovation Promotion Association(no.2015147)CAS and National Program on Key Basic Research Project(973 Program,2012CB215500)+1 种基金the Outstanding Youngest Scientist FoundationChinese Academy of Sciences(CAS)
文摘Oxygen evolution reaction（OER） is one of the most important reactions in the energy storage devices such as metal–air batteries and unitized regenerative fuel cells（URFCs）. However, the kinetically sluggishness of OER and the high prices as well as the scarcity of the most active precious metal electrocatalysts are the major bottleneck in these devices. Developing low-cost non-precious metal catalysts with high activity and stability for OER is highly desirable. A facile, in situ template method combining the dodecyl benzene sulfuric acid sodium（SDBS） assisted hydrothermal process with subsequent high-temperature treatment was developed to prepare porous Co3O4 with improved surface area and hierarchical porous structure as precious catalysts alternative for oxygen evolution reaction（OER）. Due to the unique structure, the as-prepared catalyst shows higher electrocatalytic activity than Co3O4 prepared by traditional thermal-decomposition method（noted as Co3O4-T） and commercial IrO2 catalyst for OER in 0.1M KOH aqueous solution. Moreover, it displays improved stability than Co3O4-T. The results demonstrate a highly efficient, scalable, and low cost method for developing highly active and stable OER electrocatalysts in alkaline solutions.
基金supported by the National Natural Science Foundation of China (No. 21207039)the Natural Science Foundation of Guangdong Province, China (Grant No. S2011010000737)+2 种基金the Doctoral Fund of Ministry of Education of China (20110172120017)the Fundamental Research Funds for the Central Universities (Grant No. 2011zm 0048)the Key Laboratory of Renewable Energy and Gas Hydrate, Chinese Academy of Sciences (No. Y007K1)
文摘Activated carbon （AC） supported silver catalysts were prepared by incipient wetness impregnation method and their catalytic performance for CO preferential oxidation （PROX） in excess H2 was evaluated. Ag/AC catalysts, after reduction in H2 at low temperatures （≤200 ℃） following heat treatment in He at 200 ℃ （He200H200）, exhibited the best catalytic properties. Temperature-programmed desorption （TPD）, X-ray diffraction （XRD） and temperature-programmed reduction （TPR） results indicated that silver oxides were produced during heat treatment in He at 200 ℃ which were reduced to metal silver nanoparticles in H2 at low temperatures （≤200 ℃）, simultaneously generating the adsorbed water/OH. CO conversion was enhanced 40% after water treatment following heat treatment in He at 600 ℃. These results imply that the metal silver nanoparticles are the active species and the adsorbed water/OH has noticeable promotion effects on CO oxidation. However, the promotion effect is still limited compared to gold catalysts under the similar conditions, which may be the reason of low selectivity to CO oxidation in PROX over silver catalysts. The reported Ag/AC-S-He catalyst after He200H200 treatment displayed similar PROX of CO reaction properties to Ag/SiO2. This means that Ag/AC catalyst is also an efficient low-temperature CO oxidation catalyst.
基金supported by the National Natural Science Foundation of China(no.21206202)Scientific and Technological Research Program of Chongqing Municipal Education Commission(no.KJ1600902)+2 种基金the Demonstration project of Chongqing"121"Scientific&Technological Support Project(CSTC2014zktjccx BX0089)Project of Key generic industry technologies of Chongqing(No.cstc2016zdcy-ztzx0020-02)Program for Innovative Research Team in Chongqing University of Technology(2015TD22)
