The Cu-Zr-Ce-O catalysts prepared using the coprecipitation method exhibited better catalytic performance for CO selective oxidation. The Cu-Zr-Ce-O catalysts pretreated with different methods were studied by CO-TPR a...The Cu-Zr-Ce-O catalysts prepared using the coprecipitation method exhibited better catalytic performance for CO selective oxidation. The Cu-Zr-Ce-O catalysts pretreated with different methods were studied by CO-TPR and XPS techniques. The results showed that the Cu-Zr-Ce-O catalyst pretreated with oxygen exhibited the best catalytic performance and had the widest operating temperature window, with CO conversion above 99% from 160 to 200 ℃. The O2 pretreatment caused an enrichment of the oxygen storaged on the Cu active species and promoted the conversion of adsorbed oxygen into surface lattice oxygen. It also improved the amount of Cu＋/Cu^2＋ ionic pair, and then facilitated the formation of CuO active species on the catalyst for selective CO oxidation.展开更多
The interactions of oxygen with pre-reduced silver catalysts as well as theircatalytic properties for CO selective oxidation in H_2 after oxygen pre-treatment are studied inthis paper. It is found that the pretreatmen...The interactions of oxygen with pre-reduced silver catalysts as well as theircatalytic properties for CO selective oxidation in H_2 after oxygen pre-treatment are studied inthis paper. It is found that the pretreatment exerts a strong influence on the activity andselectivity of the silver catalyst. A drop in activity and selectivity is observed after treating apre-reduced catalyst with oxygen at low temperatures, whereas a converse result is obtained after anoxidizing treatment at high temperatures (T ≥ 350℃). O_2-TPD results show that surface oxygenspecies adsorbs on silver surface after the oxygen treatment at low temperatures. However,penetration of oxygen into the silver is enhanced by a high temperature treatment, meanwhile thesurface oxygen species disappear. No other silver species except metallic silver are observed on allthe catalysts by XRD, and the size of silver particle is not changed after the treatment withoxygen at low temperatures. The surface oxygen species formed by oxygen treatment can also beremoved by hydrogen reduction. The strongly-adsorbed surface oxygen species prohibit the adsorptionand diffusion of oxygen species in reaction gas on the surface of silver catalyst, causing thedecrease in CO oxidation activity, in other words, it is important to obtain a clean silver surfacefor increasing the catalyst activity in CO removal from H_2-rich feed gas. The differences inactivity and selectivity due to the oxygen pretreatment at different temperatures are discussed interms of the changes in the surface/subsurface oxygen species of the silver particles.展开更多
CuO/CeO_2 catalysts were prepared by a coprecipitation method and tested for CO removal from reformed fuels via selective oxidation. The influence of the calcination temperature on the chemical compositions and cataly...CuO/CeO_2 catalysts were prepared by a coprecipitation method and tested for CO removal from reformed fuels via selective oxidation. The influence of the calcination temperature on the chemical compositions and catalytic performance of CuO/CeO_2 catalysts were studied. It was found that CuO/CeO_2 catalysts exhibit excellent CO oxidation activity and selectivity,and the complete removal of CO is attained when the catalysts are calcined at appropriate temperatures. XRD, TPR and XPS results indicate that CuO/CeO_2 catalysts exhibit higher catalytic performance in CO selective oxidation due to the strong interaction between copper oxide and cerium dioxide, which promotes the dispersion and hydrogen reduction activity of copper.展开更多
基金supported by the National Nature Science Foundation of China (Project No.20576023)the Natural Science Foundation of Guangdong Province (Project No.06025660).
文摘The Cu-Zr-Ce-O catalysts prepared using the coprecipitation method exhibited better catalytic performance for CO selective oxidation. The Cu-Zr-Ce-O catalysts pretreated with different methods were studied by CO-TPR and XPS techniques. The results showed that the Cu-Zr-Ce-O catalyst pretreated with oxygen exhibited the best catalytic performance and had the widest operating temperature window, with CO conversion above 99% from 160 to 200 ℃. The O2 pretreatment caused an enrichment of the oxygen storaged on the Cu active species and promoted the conversion of adsorbed oxygen into surface lattice oxygen. It also improved the amount of Cu＋/Cu^2＋ ionic pair, and then facilitated the formation of CuO active species on the catalyst for selective CO oxidation.
文摘The interactions of oxygen with pre-reduced silver catalysts as well as theircatalytic properties for CO selective oxidation in H_2 after oxygen pre-treatment are studied inthis paper. It is found that the pretreatment exerts a strong influence on the activity andselectivity of the silver catalyst. A drop in activity and selectivity is observed after treating apre-reduced catalyst with oxygen at low temperatures, whereas a converse result is obtained after anoxidizing treatment at high temperatures (T ≥ 350℃). O_2-TPD results show that surface oxygenspecies adsorbs on silver surface after the oxygen treatment at low temperatures. However,penetration of oxygen into the silver is enhanced by a high temperature treatment, meanwhile thesurface oxygen species disappear. No other silver species except metallic silver are observed on allthe catalysts by XRD, and the size of silver particle is not changed after the treatment withoxygen at low temperatures. The surface oxygen species formed by oxygen treatment can also beremoved by hydrogen reduction. The strongly-adsorbed surface oxygen species prohibit the adsorptionand diffusion of oxygen species in reaction gas on the surface of silver catalyst, causing thedecrease in CO oxidation activity, in other words, it is important to obtain a clean silver surfacefor increasing the catalyst activity in CO removal from H_2-rich feed gas. The differences inactivity and selectivity due to the oxygen pretreatment at different temperatures are discussed interms of the changes in the surface/subsurface oxygen species of the silver particles.
文摘CuO/CeO_2 catalysts were prepared by a coprecipitation method and tested for CO removal from reformed fuels via selective oxidation. The influence of the calcination temperature on the chemical compositions and catalytic performance of CuO/CeO_2 catalysts were studied. It was found that CuO/CeO_2 catalysts exhibit excellent CO oxidation activity and selectivity,and the complete removal of CO is attained when the catalysts are calcined at appropriate temperatures. XRD, TPR and XPS results indicate that CuO/CeO_2 catalysts exhibit higher catalytic performance in CO selective oxidation due to the strong interaction between copper oxide and cerium dioxide, which promotes the dispersion and hydrogen reduction activity of copper.
