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
Catalytic direct decomposition of NO by perovskite-type catalysts has attracted much attention for the various possible components and the unique structure. LaCoO_3 nanoparticles were precipitated on a-Al_2O_3 micro p...Catalytic direct decomposition of NO by perovskite-type catalysts has attracted much attention for the various possible components and the unique structure. LaCoO_3 nanoparticles were precipitated on a-Al_2O_3 micro powders by rotary chemical vapor deposition（rotary CVD） and its catalytic performance for the decomposition of NO was investigated. LaCoO_3 nano-particles with 100 nm in average diameter and 1.5% in mass were uniformly dispersed on a-Al_2O_3 powder. The conversion of NO increased with increasing temperature from 400 to 950 ℃, and reached 28.7% at 950 ℃. The gas velocity of transformed NO on LaCoO_3 nano-particles catalyst per mass unit was 7.7 mL/（g min）, showing a good catalytic activity over the calculated results of pure catalysts. After five times of aging performance experiments, the NO conversion kept the same value, showing a good aging performance and thermal stability.展开更多
Perovskite oxide LaMnO3 was prepared by sol-gel method and the nanosize Au/LaMnO3 catalyst was prepared by deposition-precipitation（DP） method in the paper.Characterization of the catalyst sample was made by X-ray d...Perovskite oxide LaMnO3 was prepared by sol-gel method and the nanosize Au/LaMnO3 catalyst was prepared by deposition-precipitation（DP） method in the paper.Characterization of the catalyst sample was made by X-ray diffractometer（XRD）,atom absorption spectra（AAS） and X-ray photoelectron spectroscopy（XPS） instrumental methods.The activity,long-term stability and the reasons for deactivation of the gold catalyst in CO oxidation were investigated.The experiment results demonstrated that the Au/LaMnO3 catalyst exhibited high stability in the ambient storage process.However,the gradual decrease in initial activity during 100 h reaction was still observed,which could be ascribed to the aggregation of gold particles and the transfer from gold ion to the metal gold.展开更多
The high cost and poor atom utilization efficiency of noble metal catalysts have limited their industrial applications. Herein, we designed CeO2-supported single Au（Ⅲ） ion catalysts with ultra-low gold loading that...The high cost and poor atom utilization efficiency of noble metal catalysts have limited their industrial applications. Herein, we designed CeO2-supported single Au（Ⅲ） ion catalysts with ultra-low gold loading that can enhance the utilization efficiency of gold atoms and bridge the gap between homogeneous and heterogeneous gold catalysis. These catalysts were highly active and reusable for the reaction of 1,3-dicarbonyls with alcohols. The catalytic turnover number of CeO2-supported single Au（III） ion catalysts was much higher than that of the homogeneous catalyst NaAuCI4. In addition, the effects of gold loading and the drying method for the catalysts on the organic reactions were systematically explored. In-depth investigation of the structure-property relationship by high- resolution transmission electron microscop~ hydrogen temperature-programmed reduction, X-ray absorption near edge structure analysis, UV-vis diffuse reflectance spectroscopy, and X-ray photoelectron spectroscopy revealed that the isolated Au（III） ions were related to the active sites for the synthesis of β-substituted cyclohexenone and that CeO2 was responsible for yielding ketonic ester.展开更多
After widely screening, a kind of bacteria was obtamed, which is casy to culture and hasstrong ability of reducing Au3+ to Au0. It was used to prepare the highly dispersive Au/a-Fe2O3catalyst by in situ reducmg the Au...After widely screening, a kind of bacteria was obtamed, which is casy to culture and hasstrong ability of reducing Au3+ to Au0. It was used to prepare the highly dispersive Au/a-Fe2O3catalyst by in situ reducmg the Au3+ ions impregnated on a-Fe2O3 supporter to Au0 particles.with a mean size of 5 nm, under the condition of 28℃ and pH 4.5. The reductive degree ofAu3+ was up to 100%. This catalyst showed good catalytic property for the oxidation of carbonmonoxide, the percent conversion of 1.5% CO, balanced withe air was up to 100% under thecondition of 25~28℃and GHSV 500mL·h-1·g-1, and the percent conversion of 100% lastedfor 75 h at 25 ℃.展开更多
So far,it is still a controversial issue which status of gold species is a better active site for catalyzing CO oxidation.Herein,the influence of the different atmospheres pretreatment(oxidative and reductive)on gold ...So far,it is still a controversial issue which status of gold species is a better active site for catalyzing CO oxidation.Herein,the influence of the different atmospheres pretreatment(oxidative and reductive)on gold state of Au/La-CeOx(1 wt%gold loading)catalyst during CO oxidation was studied.The changes of Au species were monitored by combined in situ diffuse reflectance infrared Fourier transform spectroscopy(in situ DRIFTS)and X-ray photoelectron spectroscopy(XPS).For the sample pretreated with oxidative atmosphere,the data show that the initial Au^(3+)is transformed to Au^(δ+)(0<δ<1)during CO oxidation,which is a key step to lead to higher reactivity.For the sample after reductive atmosphere pretreatment,Au^(δ+)is mixed with a small amount of Au^(0)which can be converted to Au^(δ+)with the increase of temperature in reaction.Meanwhile,the sample always maintains high activity during the reaction.Therefore,the Au®+obtained by reductive pretreatment is more active than the Au^(3+)obtained by oxidative treatment in catalyzing CO oxidation.展开更多
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Funded by the National Natural Science Foundation of China(Nos.51372188 and 51521001)the 111 Project(B13035)+3 种基金the International Science&Technology Cooperation Program of China(2014DFA53090)the Natural Science Foundation of Hubei Province,China(2016CFA006)the National Key Research and Development Program of China(2017YFB0310400)the Fundamental Research Funds for the Central Universities(WUT:2017II43GX,2017III032)
文摘Catalytic direct decomposition of NO by perovskite-type catalysts has attracted much attention for the various possible components and the unique structure. LaCoO_3 nanoparticles were precipitated on a-Al_2O_3 micro powders by rotary chemical vapor deposition（rotary CVD） and its catalytic performance for the decomposition of NO was investigated. LaCoO_3 nano-particles with 100 nm in average diameter and 1.5% in mass were uniformly dispersed on a-Al_2O_3 powder. The conversion of NO increased with increasing temperature from 400 to 950 ℃, and reached 28.7% at 950 ℃. The gas velocity of transformed NO on LaCoO_3 nano-particles catalyst per mass unit was 7.7 mL/（g min）, showing a good catalytic activity over the calculated results of pure catalysts. After five times of aging performance experiments, the NO conversion kept the same value, showing a good aging performance and thermal stability.
基金supported by the Program for New Century Excellent Talents in University(NCET-06-0268)Natural Science Foundation of Inner Mongolia(2010ZD03)
文摘Perovskite oxide LaMnO3 was prepared by sol-gel method and the nanosize Au/LaMnO3 catalyst was prepared by deposition-precipitation（DP） method in the paper.Characterization of the catalyst sample was made by X-ray diffractometer（XRD）,atom absorption spectra（AAS） and X-ray photoelectron spectroscopy（XPS） instrumental methods.The activity,long-term stability and the reasons for deactivation of the gold catalyst in CO oxidation were investigated.The experiment results demonstrated that the Au/LaMnO3 catalyst exhibited high stability in the ambient storage process.However,the gradual decrease in initial activity during 100 h reaction was still observed,which could be ascribed to the aggregation of gold particles and the transfer from gold ion to the metal gold.
基金This work was financially supported by the National Natural Science Foundation of China （Nos. 21173269 and 21276277）, the Ministry of Science and Technology of China （No. 2011BAK15B05）, the Specialized Research Fund for the Doctoral Program of Higher Education （No. 20130007110003）.
文摘The high cost and poor atom utilization efficiency of noble metal catalysts have limited their industrial applications. Herein, we designed CeO2-supported single Au（Ⅲ） ion catalysts with ultra-low gold loading that can enhance the utilization efficiency of gold atoms and bridge the gap between homogeneous and heterogeneous gold catalysis. These catalysts were highly active and reusable for the reaction of 1,3-dicarbonyls with alcohols. The catalytic turnover number of CeO2-supported single Au（III） ion catalysts was much higher than that of the homogeneous catalyst NaAuCI4. In addition, the effects of gold loading and the drying method for the catalysts on the organic reactions were systematically explored. In-depth investigation of the structure-property relationship by high- resolution transmission electron microscop~ hydrogen temperature-programmed reduction, X-ray absorption near edge structure analysis, UV-vis diffuse reflectance spectroscopy, and X-ray photoelectron spectroscopy revealed that the isolated Au（III） ions were related to the active sites for the synthesis of β-substituted cyclohexenone and that CeO2 was responsible for yielding ketonic ester.
文摘After widely screening, a kind of bacteria was obtamed, which is casy to culture and hasstrong ability of reducing Au3+ to Au0. It was used to prepare the highly dispersive Au/a-Fe2O3catalyst by in situ reducmg the Au3+ ions impregnated on a-Fe2O3 supporter to Au0 particles.with a mean size of 5 nm, under the condition of 28℃ and pH 4.5. The reductive degree ofAu3+ was up to 100%. This catalyst showed good catalytic property for the oxidation of carbonmonoxide, the percent conversion of 1.5% CO, balanced withe air was up to 100% under thecondition of 25~28℃and GHSV 500mL·h-1·g-1, and the percent conversion of 100% lastedfor 75 h at 25 ℃.
基金Project supported by the Excellent Young Scientists Fund from the National Science Foundation of China(NSFC)(21622106)other projects from the NSFC(21771117,21805167).
文摘So far,it is still a controversial issue which status of gold species is a better active site for catalyzing CO oxidation.Herein,the influence of the different atmospheres pretreatment(oxidative and reductive)on gold state of Au/La-CeOx(1 wt%gold loading)catalyst during CO oxidation was studied.The changes of Au species were monitored by combined in situ diffuse reflectance infrared Fourier transform spectroscopy(in situ DRIFTS)and X-ray photoelectron spectroscopy(XPS).For the sample pretreated with oxidative atmosphere,the data show that the initial Au^(3+)is transformed to Au^(δ+)(0<δ<1)during CO oxidation,which is a key step to lead to higher reactivity.For the sample after reductive atmosphere pretreatment,Au^(δ+)is mixed with a small amount of Au^(0)which can be converted to Au^(δ+)with the increase of temperature in reaction.Meanwhile,the sample always maintains high activity during the reaction.Therefore,the Au®+obtained by reductive pretreatment is more active than the Au^(3+)obtained by oxidative treatment in catalyzing CO oxidation.
