采用水热法和聚合物保护的硼氢化钠还原法制备了α-MnO_2及其负载Au-Pd的催化剂,考察了催化消除乙酸乙酯、间二甲苯及二者混合物的性能.XRD、SEM和TEM以及H2-TPR表征催化剂的物化性质.在反应物浓度为1000 mg/L,与O_2摩尔比为1:400,空速...采用水热法和聚合物保护的硼氢化钠还原法制备了α-MnO_2及其负载Au-Pd的催化剂,考察了催化消除乙酸乙酯、间二甲苯及二者混合物的性能.XRD、SEM和TEM以及H2-TPR表征催化剂的物化性质.在反应物浓度为1000 mg/L,与O_2摩尔比为1:400,空速为40000 m L/(g·h)的条件下,0.91Au0.48Pd/α-MnO_2比α-MnO_2的催化性能优越与其具有更好的低温还原性能有关.展开更多
Heterogeneous gold nanocatalysts have both inspired researchers with their unique catalytic performance and frustrated them due to the contradictions observed in their activities and stabilities.A recent breakthrough ...Heterogeneous gold nanocatalysts have both inspired researchers with their unique catalytic performance and frustrated them due to the contradictions observed in their activities and stabilities.A recent breakthrough has shown that gold nanoparticles(NPs)can retain their catalytically active size over a MgGa2O4 spinel support upon sintering at high temperatures.Herein,we report the catalytic activity of anti-sintering AuGMgGa2O4 for use in water gas shift reaction(WGSR)and catalytic combustion reactions,and the promoting effect of ceria.Upon adding ceria to 800℃-aged AuGMgGa2O4,the CO conversion in the WGSR was increased from ~1.5% to ~34.0% at 450 ℃,and the “light-off” temperatures(T50)for methane combustion and CO oxidation were decreased by ~80 and ~100 ℃,respectively.Characterizations using XRD,HAADF-STEM,EDS mapping,H2-TPR,XPS,and DRIFTs confirmed the proximate contact of Au with ceria and their significant synergistic effect,which thereby combined the benefits of ceria toward the dissociation of H2O or O2 and the Au NPs toward activating CO or CH4.These results show that this stepwise stabilization-activation strategy is efficient for rationally constructing stable and active gold nanocatalysts,which may open up possibilities for the wide application of gold nanocatalysts at elevated temperatures.展开更多
Gold has been regarded as a poor heterogeneous catalyst because it is generally considered a nonreactive metal. But as nanocatalysts,gold and other metals somehow significantly enhance reactivity. It is generally thou...Gold has been regarded as a poor heterogeneous catalyst because it is generally considered a nonreactive metal. But as nanocatalysts,gold and other metals somehow significantly enhance reactivity. It is generally thought chemical bonds of reactants are weakened by adsorption to nanocatalysts thereby allowing reactions to proceed more rapidly,but how this reaction proceeds to completion is not well understood. Here gold nanocatalysts are treated as unsupported nanoparticles (NPs) in a solution of reactant molecules from which extensions are made to gold NPs supported on titanium dioxide. Whether the NPs are supported or unsupported,enhanced catalytic reactivity depends on absorbed thermal kT (k is Boltzmann's constant and T is absolute temperature) energy accumulated from prior collisions of reactant molecules. The accumulated kT energy is treated as electromagnetic thereby allowing frequency up-conversion by quantum electrodynamics (QED) to the confinement frequency of the NP,typically beyond the vacuum ultraviolet (VUV). By this theory,the chemical reaction of reactant molecules having bonds weakened by adsorption is completed by QED induced VUV photolysis.展开更多
Au nanoparticles epitaxially grown on Fe_(3)O_(4)in Au(6.7 nm)-Fe_(3)O_(4)dumbbell nanoparticles exhibit excellent stability against sintering,but display negligible catalytic activity in CO oxidation.Starting from va...Au nanoparticles epitaxially grown on Fe_(3)O_(4)in Au(6.7 nm)-Fe_(3)O_(4)dumbbell nanoparticles exhibit excellent stability against sintering,but display negligible catalytic activity in CO oxidation.Starting from various supported Au(6.7 nm)-Fe_(3)O_(4)catalysts prepared by the colloidal deposition method,we have unambiguously identifi ed the significance of the Au-TiO_(2)interface in CO oxidation,without any possible size effect of Au.In situ thermal decomposition of TiO_(2)precursors on Au-Fe_(3)O_(4)was found to be an effective way to increase the Au-TiO_(2)interface and thereby optimize the catalytic performance of TiO_(2)-supported Au-Fe_(3)O_(4)dumbbell nanoparticles.By reducing the size of Fe_(3)O_(4)from 15.2 to 4.9 nm,the Au-TiO_(2)contact was further increased so that the resulting TiO_(2)-supported Au(6.7 nm)-Fe_(3)O_(4)(4.9 nm)dumbbell particles become highly efficient catalysts for CO oxidation at room temperature.展开更多
文摘采用水热法和聚合物保护的硼氢化钠还原法制备了α-MnO_2及其负载Au-Pd的催化剂,考察了催化消除乙酸乙酯、间二甲苯及二者混合物的性能.XRD、SEM和TEM以及H2-TPR表征催化剂的物化性质.在反应物浓度为1000 mg/L,与O_2摩尔比为1:400,空速为40000 m L/(g·h)的条件下,0.91Au0.48Pd/α-MnO_2比α-MnO_2的催化性能优越与其具有更好的低温还原性能有关.
基金supported by the National Key R&D Program of China(2016YFA0202801)the National Natural Science Foundation of China(21403213,21673226)+1 种基金the"Transformational Technologies for Clean Energy and Demonstration"Strategic Priority Research Program of the Chinese Academy of Sciences(XDA21040200)the "Hundred Talents Programme" of the Chinese Academy of Sciences~~
文摘Heterogeneous gold nanocatalysts have both inspired researchers with their unique catalytic performance and frustrated them due to the contradictions observed in their activities and stabilities.A recent breakthrough has shown that gold nanoparticles(NPs)can retain their catalytically active size over a MgGa2O4 spinel support upon sintering at high temperatures.Herein,we report the catalytic activity of anti-sintering AuGMgGa2O4 for use in water gas shift reaction(WGSR)and catalytic combustion reactions,and the promoting effect of ceria.Upon adding ceria to 800℃-aged AuGMgGa2O4,the CO conversion in the WGSR was increased from ~1.5% to ~34.0% at 450 ℃,and the “light-off” temperatures(T50)for methane combustion and CO oxidation were decreased by ~80 and ~100 ℃,respectively.Characterizations using XRD,HAADF-STEM,EDS mapping,H2-TPR,XPS,and DRIFTs confirmed the proximate contact of Au with ceria and their significant synergistic effect,which thereby combined the benefits of ceria toward the dissociation of H2O or O2 and the Au NPs toward activating CO or CH4.These results show that this stepwise stabilization-activation strategy is efficient for rationally constructing stable and active gold nanocatalysts,which may open up possibilities for the wide application of gold nanocatalysts at elevated temperatures.
文摘Gold has been regarded as a poor heterogeneous catalyst because it is generally considered a nonreactive metal. But as nanocatalysts,gold and other metals somehow significantly enhance reactivity. It is generally thought chemical bonds of reactants are weakened by adsorption to nanocatalysts thereby allowing reactions to proceed more rapidly,but how this reaction proceeds to completion is not well understood. Here gold nanocatalysts are treated as unsupported nanoparticles (NPs) in a solution of reactant molecules from which extensions are made to gold NPs supported on titanium dioxide. Whether the NPs are supported or unsupported,enhanced catalytic reactivity depends on absorbed thermal kT (k is Boltzmann's constant and T is absolute temperature) energy accumulated from prior collisions of reactant molecules. The accumulated kT energy is treated as electromagnetic thereby allowing frequency up-conversion by quantum electrodynamics (QED) to the confinement frequency of the NP,typically beyond the vacuum ultraviolet (VUV). By this theory,the chemical reaction of reactant molecules having bonds weakened by adsorption is completed by QED induced VUV photolysis.
基金We thank the National Natural Science Foundation of China(Nos.20871100,20721001)a Distinguished Young Investigator Grant(No.20925103)+2 种基金Research Fund for the Doctoral Program of Higher Education of China(No.200803841010)Natural Science Foundation of Fujian for a Distinguished Young Investigator Grant(No.2009J06005)the Key Scientific Project of Fujian Province(No.2009HZ0002-1).
文摘Au nanoparticles epitaxially grown on Fe_(3)O_(4)in Au(6.7 nm)-Fe_(3)O_(4)dumbbell nanoparticles exhibit excellent stability against sintering,but display negligible catalytic activity in CO oxidation.Starting from various supported Au(6.7 nm)-Fe_(3)O_(4)catalysts prepared by the colloidal deposition method,we have unambiguously identifi ed the significance of the Au-TiO_(2)interface in CO oxidation,without any possible size effect of Au.In situ thermal decomposition of TiO_(2)precursors on Au-Fe_(3)O_(4)was found to be an effective way to increase the Au-TiO_(2)interface and thereby optimize the catalytic performance of TiO_(2)-supported Au-Fe_(3)O_(4)dumbbell nanoparticles.By reducing the size of Fe_(3)O_(4)from 15.2 to 4.9 nm,the Au-TiO_(2)contact was further increased so that the resulting TiO_(2)-supported Au(6.7 nm)-Fe_(3)O_(4)(4.9 nm)dumbbell particles become highly efficient catalysts for CO oxidation at room temperature.
