Using SnxTi1-xO2 as carriers, CuO/Sn0.9Zi0.1O2 and CuO/Sn0.7Ti0.3O2 catalysts with different loading amounts of copper oxide （CuO） were prepared by an impregnation method. The catalytic properties of CuO/Sn0.9Ti0.1O...Using SnxTi1-xO2 as carriers, CuO/Sn0.9Zi0.1O2 and CuO/Sn0.7Ti0.3O2 catalysts with different loading amounts of copper oxide （CuO） were prepared by an impregnation method. The catalytic properties of CuO/Sn0.9Ti0.1O2 and CuO/Sn0.7Zi0.3O2 were examined using a microreactor-gas chromatography （GC） NO＋CO reaction system and the methods of BET （Brun- auer-Emmett-Teller）, TG-DTA （themogravimetric and differential thermal analysis）, X-ray diffraction （XRD） and H2-temperature programmed reduction （TPR）. The results showed that NO conversions of Sn0.9Zi0.1O2 and Sn0.7Ti0.3O2 were 47.2% and 43.6% respectively, which increased to 95.3% and 90.9% at 6 wt% CuO loading. However, further increase in CuO loading caused a decrease in the catalytic activity. The nitrogen adsorption-desorption isotherm and pore-size distribution curve of Sn0.9Zi0.1O2 and Sn0.7Ti0.3O2 represented type IV of the BDDT （Brunauer, Deming, Deming and Teller） system and a typical mesoporous sample. There were two CuO diffraction peaks （2θ 35.5° and 38.7°）, and the diffraction peak areas increased with increasing CuO loading. TPR analysis also detected three peaks （α, β and γ） from the CuO-loaded catalysts, suggesting that the α peak was the reduction of the highly dispersed copper oxide, the β peak was the reduction of the isolated copper oxide, and the y peak was the reduction of crystal phase copper oxide. In addition, a fourth peak （5） of the catalysts meant that the SnxTi1-xO2 mixed oxides could be reductive.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Project (No. Y504131) supported by the Natural Science Foundation of Zhejiang Province, China
文摘Using SnxTi1-xO2 as carriers, CuO/Sn0.9Zi0.1O2 and CuO/Sn0.7Ti0.3O2 catalysts with different loading amounts of copper oxide （CuO） were prepared by an impregnation method. The catalytic properties of CuO/Sn0.9Ti0.1O2 and CuO/Sn0.7Zi0.3O2 were examined using a microreactor-gas chromatography （GC） NO＋CO reaction system and the methods of BET （Brun- auer-Emmett-Teller）, TG-DTA （themogravimetric and differential thermal analysis）, X-ray diffraction （XRD） and H2-temperature programmed reduction （TPR）. The results showed that NO conversions of Sn0.9Zi0.1O2 and Sn0.7Ti0.3O2 were 47.2% and 43.6% respectively, which increased to 95.3% and 90.9% at 6 wt% CuO loading. However, further increase in CuO loading caused a decrease in the catalytic activity. The nitrogen adsorption-desorption isotherm and pore-size distribution curve of Sn0.9Zi0.1O2 and Sn0.7Ti0.3O2 represented type IV of the BDDT （Brunauer, Deming, Deming and Teller） system and a typical mesoporous sample. There were two CuO diffraction peaks （2θ 35.5° and 38.7°）, and the diffraction peak areas increased with increasing CuO loading. TPR analysis also detected three peaks （α, β and γ） from the CuO-loaded catalysts, suggesting that the α peak was the reduction of the highly dispersed copper oxide, the β peak was the reduction of the isolated copper oxide, and the y peak was the reduction of crystal phase copper oxide. In addition, a fourth peak （5） of the catalysts meant that the SnxTi1-xO2 mixed oxides could be reductive.
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.
