ZrO2-MnO2-ZnO supports were prepared by the co-precipitation method,and then Ni-Na/ZrO2-MnO2-ZnO catalysts were prepared by the impregnation method.In this paper,the reactions to synthesize methyl isopropyl ketone and...ZrO2-MnO2-ZnO supports were prepared by the co-precipitation method,and then Ni-Na/ZrO2-MnO2-ZnO catalysts were prepared by the impregnation method.In this paper,the reactions to synthesize methyl isopropyl ketone and diethyl ketone by the one-step synthesis method over this catalyst were studied,and meanwhile,the impact of the catalyst preparation conditions and the reaction conditions on catalyst performance was also investigated.It was observed that under the conditions when Ni loading was 25%,calcination temperature was 400℃ and reduction temperature was 410℃,this catalyst had good catalytic performance on the reaction.The suitable reaction conditions were achieved:reaction temperature was 400℃;reaction at atmospheric pressure;liquid hourly space velocity of raw material of 0.5 h 1 ;and the molar ratio of(methanol)/(methyl ethyl ketone)/(water) was equal to 1/1/1.Under such conditions,the conversion of methyl ethyl ketone could achieve 41.7%,and the overall selectivity of methyl isopropyl ketone and diethyl ketone could achieve 83.3%,which was comparable to the conversion of 38.1% and the selectivity of 82.2% achieved by using palladium as the active material.The good stability made this catalyst have good prospects for industrial application.展开更多
Au/FeOx-TiO2,prepared by deposition-precipitation method,is an efficient and stable catalyst for the liquid phase selective hydrogenation of phthalic anhydride to phthalide under mild reaction conditions.
We examined the water adsorption and dissociation on ceria surfaces as well as ceria‐supported Au single‐atom catalysts using density functional theory calculations.Molecular and dissociative water were observed to ...We examined the water adsorption and dissociation on ceria surfaces as well as ceria‐supported Au single‐atom catalysts using density functional theory calculations.Molecular and dissociative water were observed to coexist on clean CeO2and reduced Au1/CeO2?x surfaces because of the small difference in adsorption energies,whereas the presence of dissociative water was highly favorable on reduced CeO2?x and clean Au1/CeO2surfaces.Positively charged Au single atoms on the ceria surface not only provided activation sites for water adsorption but also facilitated water dissociation by weakening the intramolecular O-H bonds.In contrast,negatively charged Au single atoms were not reactive for water adsorption because of the saturation of Au5d and6s electron shells.This work provides a fundamental understanding of the interaction between water and single‐atom Au catalysts.展开更多
Au/Al2O3 catalyst was prepared by a modified anion impregnation method and investigated with respect to its initial activity and stability for low-temperature CO oxidation.The activity changes of the catalyst were exa...Au/Al2O3 catalyst was prepared by a modified anion impregnation method and investigated with respect to its initial activity and stability for low-temperature CO oxidation.The activity changes of the catalyst were examined after separate treatment in CO＋O2 or CO2 ＋O2 .Furthermore,in situ FT-IR studies were performed to investigate the species on the surface when CO or CO＋O2 or CO2 ＋O2 was selected separately as adsorption gas.The results showed that Au/Al2O3 catalyst exhibited very high initial activity,but the catalytic activity was found to decrease gradually during CO oxidation with time on stream.And also,the activity of the catalyst declined after treatment in CO＋O2 or CO2 ＋O2 .The formation and accumulation of carbonate-like species during CO oxidation or treatment in CO＋O2 or CO2 ＋O2 might be mainly responsible for the activity decrease,which was reversible.展开更多
Development of active and stable catalysts for low-temperature CO oxidation has long been regarded as a hot topic.In this contribution,we used CeO_(2) with high-density surface pits as support to prepare an active and...Development of active and stable catalysts for low-temperature CO oxidation has long been regarded as a hot topic.In this contribution,we used CeO_(2) with high-density surface pits as support to prepare an active and stable Au/CeO_(2) catalyst by an adsorption-deposition method.The obtained 0.05 wt%Au/CeO_(2)-TD(where TD represents thermal decomposition)can maintain its activity at 80℃ for more than 20 h or even after calcination at 800℃ for 2 h.The characterization results showed that the high-density surface pits on CeO_(2)-TD play a decisive role in the stabilization of Au and enhancement of the redox property.This work may provide a new strategy to improve the stability of supported metal catalysts by a simple and conventional method.展开更多
气氛环境下原位研究催化剂的烧结行为,能够为理解催化剂在预处理以及反应条件下的烧结机理和高稳定催化剂的设计提供重要的实验依据。本文以Au/CeO_(2)模型纳米催化剂为研究对象,利用环境透射电子显微镜原位观察其在O_(2)与CO气氛下的...气氛环境下原位研究催化剂的烧结行为,能够为理解催化剂在预处理以及反应条件下的烧结机理和高稳定催化剂的设计提供重要的实验依据。本文以Au/CeO_(2)模型纳米催化剂为研究对象,利用环境透射电子显微镜原位观察其在O_(2)与CO气氛下的高温动态烧结过程。实验发现,负载在CeO_(2)上的Au纳米颗粒在O_(2)与CO气氛环境中表现出不同的烧结行为,其在O_(2)气氛下具有较高的烧结速度,同时存在颗粒迁移与聚集长大(particle migration and coalescence,PMC)和奥斯特瓦尔德熟化(Ostwald ripening,OR)两种烧结过程;在CO气氛下烧结速度较慢,烧结过程以OR为主。对比不同气氛环境下烧结后催化剂的表面结构可知,CO增加了CeO_(2)表面台阶的数量以及表面氧空位浓度,增强了载体对Au颗粒的锚定作用,从而提升Au/CeO_(2)催化剂的稳定性。展开更多
The supported Au/TiO2 and Au/TiO2-SiO2 catalysts were prepared by deposition precipitation method. The TPD study reveals that propylene oxide competes with propylene to be adsorbed on the same adsorptive center-Ti^n＋...The supported Au/TiO2 and Au/TiO2-SiO2 catalysts were prepared by deposition precipitation method. The TPD study reveals that propylene oxide competes with propylene to be adsorbed on the same adsorptive center-Ti^n＋ site on the surface of the catalyst and that the adisorbing capacity of the catalyst for propylene oxide is larger than that for propylene. Catalytic behavior for propylene epoxidation with H2 and O2 was tested in a micro-reactor. Under typical conditions, the selectivity for propylene oxide is over 87%. The TG curves show that PO successive oxidation cause carbon deposition on the active center and deactivation of the Au catalysts. Because the amounts of Tin＋ site decrease significantly, and consequently the separation between Ti^n＋ sites increases, the Au/TiO2-SiO2 catalyst is more stable than Au/TiO2.展开更多
Au/TiO_(2) catalyst is firstly reported to be efficient in the hydrogenation of nitrobenzene to produce p-aminophenol with a high PAP selectivity of 81%and overall yield more than 63%.The catalyst is also quite stable...Au/TiO_(2) catalyst is firstly reported to be efficient in the hydrogenation of nitrobenzene to produce p-aminophenol with a high PAP selectivity of 81%and overall yield more than 63%.The catalyst is also quite stable and can be reused for at least 4 times with only slight decrease in activity.展开更多
The γ-MnO_2@CNT catalyst was prepared by in situ solid phase synthesis and first applied into sodium-air batteries(SABs). The initial discharge specific capacity of SABs with γ-MnO_2@CNT catalyst can reach 8804 mA h...The γ-MnO_2@CNT catalyst was prepared by in situ solid phase synthesis and first applied into sodium-air batteries(SABs). The initial discharge specific capacity of SABs with γ-MnO_2@CNT catalyst can reach 8804 mA h g^(-1) and the overpotential gap is only 140 m V, which is better than the batteries that is catalyzed by α-MnO_2@CNT and pure CNT. Besides, the batteries also exhibit excellent cycle performance, which can keep relatively stable for 246 cycles at 500 mA g^(-1) and 140 cycles at1000 mA g^(-1).展开更多
The sorption of AuCL4- ,AuCl2- and Au(S2O3)23- on δ-MnO2 was investigated at pH2-11.6, 0.01 mol/L and 0.1 mol/L NaNO3 solutions. At pH 4 in two electrolyte strength solutions, Au sorption densities on δ-MnO2 are 0. ...The sorption of AuCL4- ,AuCl2- and Au(S2O3)23- on δ-MnO2 was investigated at pH2-11.6, 0.01 mol/L and 0.1 mol/L NaNO3 solutions. At pH 4 in two electrolyte strength solutions, Au sorption densities on δ-MnO2 are 0. 18-0.21 and 0.28 μmoL/m2 for AuCl4 and Au(S2O3)23- , respectively, and the Au surface coverage is approximate to or lower than 1 % . This adsorption of the two Au complexes decreases as the solution pH increases, which conforms to the sorption regularity of the anion on δ-MnO2. The Au sorption decreases in the sequence of Au(S2O3)23- >AuCl4- > AuCl2- . The intrinsic equilibrium constants (logKint) of the three Au complexes are 1.17-2.7, much higher than those of Cu and Cd. The hydrolysis products of AuCLi are preferentially adsorbed by δ-MnO2 and the inner-sphere Au-surface complexes are formed on the surface.展开更多
As efficient catalysts of electrochemical CO_(2)reduction reaction(CO_(2)RR)towards multicarbon(C_(2+))products,Cu-based catalysts have faced the challenges of increasing the reactive activity and selectivity.Herein,w...As efficient catalysts of electrochemical CO_(2)reduction reaction(CO_(2)RR)towards multicarbon(C_(2+))products,Cu-based catalysts have faced the challenges of increasing the reactive activity and selectivity.Herein,we decorated the surface of Cu nanowires(Cu NWs)with a small amount of Au nanoparticles(Au NPs)by the homo-nucleation method.When the Au to Cu mass ratio is as little as 0.7 to 99.3,the gold-doped copper nanowires(Cu-Au NWs)could effectively improve the selectivity and activity of CO_(2)RR to C_(2+)resultants,with the Faradaic efficiency(FE)from 39.7%(Cu NWs)to 65.3%,the partial current density from 7.0(Cu NWs)to 12.1 mA/cm^(2) under−1.25 V vs.reversible hydrogen electrode(RHE).The enhanced electrocatalytic performance could be attributed to the following three synergetic factors.The addition of Au nanoparticles caused a rougher surface of the catalyst,which allowed for more active sites exposed.Besides,Au sites generated*CO intermediates spilling over into Cu sites with the calculated efficiency of 87.2%,which are necessary for multicarbon production.Meanwhile,the interphase electron transferred from Cu to Au induced the electron-deficient Cu,which favored the adsorption of*CO to further generate multicarbon productions.Our results uncovered the morphology,tandem,electronic effect between Cu NWs and Au NPs facilitated the activity and selectivity of CO_(2)RR to multicarbons.展开更多
MnO2 microspheres with various surface structures were prepared using the hydrothermal method, and Au/MnO2 catalysts were synthesized using the sol-gel method. We obtained three MnO2 microspheres and Au/MnO2 samp...MnO2 microspheres with various surface structures were prepared using the hydrothermal method, and Au/MnO2 catalysts were synthesized using the sol-gel method. We obtained three MnO2 microspheres and Au/MnO2 samples： coherent solid spheres covered with wire-like nanostructures, solid spheres with nanosheets, and hierarchical hollow microspheres with nanoplatelets and nanorods. We investigated the properties and catalytic activities of formaldehyde oxidation at room temperature. Crystalline structures of MnO2 are the main factor affecting the catalytic activities of these samples, and γ- MnO2 shows high catalytic performance. The excellent redox properties are responsible for the catalytic ability of γ-MnO2. The gold-supported interaction can change the redox properties of catalysts and accelerate surface oxygen species transition, which can account for the catalytic activity enhancement of Au/MnO2. We also studied intermediate species. The dioxymethylene （DOM） and formate species formed on the catalyst surface were considered intermediates, and were ultimately transformed into hydrocarbonate and carbonate and then decomposed into CO2. A proposed mechanism of formaldehyde oxidation over Au/MnO2 catalysts was also obtained.展开更多
基金Supported by the National Science and Technology Support Program Project (2006BAE03B06)
文摘ZrO2-MnO2-ZnO supports were prepared by the co-precipitation method,and then Ni-Na/ZrO2-MnO2-ZnO catalysts were prepared by the impregnation method.In this paper,the reactions to synthesize methyl isopropyl ketone and diethyl ketone by the one-step synthesis method over this catalyst were studied,and meanwhile,the impact of the catalyst preparation conditions and the reaction conditions on catalyst performance was also investigated.It was observed that under the conditions when Ni loading was 25%,calcination temperature was 400℃ and reduction temperature was 410℃,this catalyst had good catalytic performance on the reaction.The suitable reaction conditions were achieved:reaction temperature was 400℃;reaction at atmospheric pressure;liquid hourly space velocity of raw material of 0.5 h 1 ;and the molar ratio of(methanol)/(methyl ethyl ketone)/(water) was equal to 1/1/1.Under such conditions,the conversion of methyl ethyl ketone could achieve 41.7%,and the overall selectivity of methyl isopropyl ketone and diethyl ketone could achieve 83.3%,which was comparable to the conversion of 38.1% and the selectivity of 82.2% achieved by using palladium as the active material.The good stability made this catalyst have good prospects for industrial application.
基金support provided by Zhejiang Provincial Natural Science Foundation of China(No.Y405108)the Department of Education of Zhejiang Province of China(No.20051409)
文摘Au/FeOx-TiO2,prepared by deposition-precipitation method,is an efficient and stable catalyst for the liquid phase selective hydrogenation of phthalic anhydride to phthalide under mild reaction conditions.
基金supported by the National Natural Science Foundation of China(21590792,91645203 and 21521091)~~
文摘We examined the water adsorption and dissociation on ceria surfaces as well as ceria‐supported Au single‐atom catalysts using density functional theory calculations.Molecular and dissociative water were observed to coexist on clean CeO2and reduced Au1/CeO2?x surfaces because of the small difference in adsorption energies,whereas the presence of dissociative water was highly favorable on reduced CeO2?x and clean Au1/CeO2surfaces.Positively charged Au single atoms on the ceria surface not only provided activation sites for water adsorption but also facilitated water dissociation by weakening the intramolecular O-H bonds.In contrast,negatively charged Au single atoms were not reactive for water adsorption because of the saturation of Au5d and6s electron shells.This work provides a fundamental understanding of the interaction between water and single‐atom Au catalysts.
基金supported by the Science and Research Reward Fund Program of Shandong Excellent Young Scientist of China (2007BS04033)
文摘Au/Al2O3 catalyst was prepared by a modified anion impregnation method and investigated with respect to its initial activity and stability for low-temperature CO oxidation.The activity changes of the catalyst were examined after separate treatment in CO＋O2 or CO2 ＋O2 .Furthermore,in situ FT-IR studies were performed to investigate the species on the surface when CO or CO＋O2 or CO2 ＋O2 was selected separately as adsorption gas.The results showed that Au/Al2O3 catalyst exhibited very high initial activity,but the catalytic activity was found to decrease gradually during CO oxidation with time on stream.And also,the activity of the catalyst declined after treatment in CO＋O2 or CO2 ＋O2 .The formation and accumulation of carbonate-like species during CO oxidation or treatment in CO＋O2 or CO2 ＋O2 might be mainly responsible for the activity decrease,which was reversible.
基金financially supported by the National Key Research and Development Program of China(No.2016YFC0204300)the National Natural Science Foundation of China(Nos.21571061,21333003 and 21908079)Pujiang Program of the Shanghai Municipal Human Resources and Social Security Bureau(No.18PJD011)。
文摘Development of active and stable catalysts for low-temperature CO oxidation has long been regarded as a hot topic.In this contribution,we used CeO_(2) with high-density surface pits as support to prepare an active and stable Au/CeO_(2) catalyst by an adsorption-deposition method.The obtained 0.05 wt%Au/CeO_(2)-TD(where TD represents thermal decomposition)can maintain its activity at 80℃ for more than 20 h or even after calcination at 800℃ for 2 h.The characterization results showed that the high-density surface pits on CeO_(2)-TD play a decisive role in the stabilization of Au and enhancement of the redox property.This work may provide a new strategy to improve the stability of supported metal catalysts by a simple and conventional method.
文摘气氛环境下原位研究催化剂的烧结行为,能够为理解催化剂在预处理以及反应条件下的烧结机理和高稳定催化剂的设计提供重要的实验依据。本文以Au/CeO_(2)模型纳米催化剂为研究对象,利用环境透射电子显微镜原位观察其在O_(2)与CO气氛下的高温动态烧结过程。实验发现,负载在CeO_(2)上的Au纳米颗粒在O_(2)与CO气氛环境中表现出不同的烧结行为,其在O_(2)气氛下具有较高的烧结速度,同时存在颗粒迁移与聚集长大(particle migration and coalescence,PMC)和奥斯特瓦尔德熟化(Ostwald ripening,OR)两种烧结过程;在CO气氛下烧结速度较慢,烧结过程以OR为主。对比不同气氛环境下烧结后催化剂的表面结构可知,CO增加了CeO_(2)表面台阶的数量以及表面氧空位浓度,增强了载体对Au颗粒的锚定作用,从而提升Au/CeO_(2)催化剂的稳定性。
基金Supported by the National Natural Science Foundation of China (29773031).
文摘The supported Au/TiO2 and Au/TiO2-SiO2 catalysts were prepared by deposition precipitation method. The TPD study reveals that propylene oxide competes with propylene to be adsorbed on the same adsorptive center-Ti^n＋ site on the surface of the catalyst and that the adisorbing capacity of the catalyst for propylene oxide is larger than that for propylene. Catalytic behavior for propylene epoxidation with H2 and O2 was tested in a micro-reactor. Under typical conditions, the selectivity for propylene oxide is over 87%. The TG curves show that PO successive oxidation cause carbon deposition on the active center and deactivation of the Au catalysts. Because the amounts of Tin＋ site decrease significantly, and consequently the separation between Ti^n＋ sites increases, the Au/TiO2-SiO2 catalyst is more stable than Au/TiO2.
基金supported by the National Natural Science Foundation of China(21978325 and 22122807)Outstanding Youth Fund of the National Natural Science Foundation of China(22122807)+1 种基金Outstanding Youth Fund of Shandong Provincial Natural Science Foundation(ZR2020YQ17)Natural Science Foundation of Shandong Province(ZR2020KB006)。
基金Financial support by the Major State Basic Resource Development Program(Grant No.2012CB224804)NSFC(Project Nos.21373054,21173052)+1 种基金the Natural Science Foundation of Shanghai Science and Technol-ogy Committee(No.08DZ2270500)Hui-Chun Chin and Tsung-Dao Lee Chinese Undergraduate Re-search Endowment(CURE).
文摘Au/TiO_(2) catalyst is firstly reported to be efficient in the hydrogenation of nitrobenzene to produce p-aminophenol with a high PAP selectivity of 81%and overall yield more than 63%.The catalyst is also quite stable and can be reused for at least 4 times with only slight decrease in activity.
基金supported by the National Key R&D Program (2016YFB0901502, 2016YFB0101201)the National Natural Science Foundation of China (NSFC) (51771094)Ministry of Education (B12015), and Tianjin High-Tech (18JCZDJC31500)
文摘The γ-MnO_2@CNT catalyst was prepared by in situ solid phase synthesis and first applied into sodium-air batteries(SABs). The initial discharge specific capacity of SABs with γ-MnO_2@CNT catalyst can reach 8804 mA h g^(-1) and the overpotential gap is only 140 m V, which is better than the batteries that is catalyzed by α-MnO_2@CNT and pure CNT. Besides, the batteries also exhibit excellent cycle performance, which can keep relatively stable for 246 cycles at 500 mA g^(-1) and 140 cycles at1000 mA g^(-1).
基金Project supported by the National Studying-abroad Foundation, the National Natural Science Foundation of China (Grant No. 49573200) and the Australian Mining Industry.
文摘The sorption of AuCL4- ,AuCl2- and Au(S2O3)23- on δ-MnO2 was investigated at pH2-11.6, 0.01 mol/L and 0.1 mol/L NaNO3 solutions. At pH 4 in two electrolyte strength solutions, Au sorption densities on δ-MnO2 are 0. 18-0.21 and 0.28 μmoL/m2 for AuCl4 and Au(S2O3)23- , respectively, and the Au surface coverage is approximate to or lower than 1 % . This adsorption of the two Au complexes decreases as the solution pH increases, which conforms to the sorption regularity of the anion on δ-MnO2. The Au sorption decreases in the sequence of Au(S2O3)23- >AuCl4- > AuCl2- . The intrinsic equilibrium constants (logKint) of the three Au complexes are 1.17-2.7, much higher than those of Cu and Cd. The hydrolysis products of AuCLi are preferentially adsorbed by δ-MnO2 and the inner-sphere Au-surface complexes are formed on the surface.
基金the National Key Research and Development Program of China(Nos.2017YFA0700103,2018YFA0704502,and 2021YFA1501500)the National Natural Science Foundation of China(NSFC)(No.22033008)Fujian Science&Technology Innovation Laboratory for Optoelectronic Information of China(No.2021ZZ103).
文摘As efficient catalysts of electrochemical CO_(2)reduction reaction(CO_(2)RR)towards multicarbon(C_(2+))products,Cu-based catalysts have faced the challenges of increasing the reactive activity and selectivity.Herein,we decorated the surface of Cu nanowires(Cu NWs)with a small amount of Au nanoparticles(Au NPs)by the homo-nucleation method.When the Au to Cu mass ratio is as little as 0.7 to 99.3,the gold-doped copper nanowires(Cu-Au NWs)could effectively improve the selectivity and activity of CO_(2)RR to C_(2+)resultants,with the Faradaic efficiency(FE)from 39.7%(Cu NWs)to 65.3%,the partial current density from 7.0(Cu NWs)to 12.1 mA/cm^(2) under−1.25 V vs.reversible hydrogen electrode(RHE).The enhanced electrocatalytic performance could be attributed to the following three synergetic factors.The addition of Au nanoparticles caused a rougher surface of the catalyst,which allowed for more active sites exposed.Besides,Au sites generated*CO intermediates spilling over into Cu sites with the calculated efficiency of 87.2%,which are necessary for multicarbon production.Meanwhile,the interphase electron transferred from Cu to Au induced the electron-deficient Cu,which favored the adsorption of*CO to further generate multicarbon productions.Our results uncovered the morphology,tandem,electronic effect between Cu NWs and Au NPs facilitated the activity and selectivity of CO_(2)RR to multicarbons.
基金This work is financially supported by the National Natural Science Foundation of China （Grant Nos. 21107124 and 21337003）, Dean＇s Award Startup Funds of the Chinese Academy of Sciences, the National High Technology Research and Development Program of China （No. 2012AA063101）, and Science Promotion Program of Research Center for Eco-Environmcntal Sciences, CAS （YSW2013B05）.
文摘MnO2 microspheres with various surface structures were prepared using the hydrothermal method, and Au/MnO2 catalysts were synthesized using the sol-gel method. We obtained three MnO2 microspheres and Au/MnO2 samples： coherent solid spheres covered with wire-like nanostructures, solid spheres with nanosheets, and hierarchical hollow microspheres with nanoplatelets and nanorods. We investigated the properties and catalytic activities of formaldehyde oxidation at room temperature. Crystalline structures of MnO2 are the main factor affecting the catalytic activities of these samples, and γ- MnO2 shows high catalytic performance. The excellent redox properties are responsible for the catalytic ability of γ-MnO2. The gold-supported interaction can change the redox properties of catalysts and accelerate surface oxygen species transition, which can account for the catalytic activity enhancement of Au/MnO2. We also studied intermediate species. The dioxymethylene （DOM） and formate species formed on the catalyst surface were considered intermediates, and were ultimately transformed into hydrocarbonate and carbonate and then decomposed into CO2. A proposed mechanism of formaldehyde oxidation over Au/MnO2 catalysts was also obtained.
