Due to coexisting of H2, CO2 and H2O with CO in hydrogen-rich gas produced from methanol reforming, the selective CO oxidation is companied with the side reactions of H2 oxidation, as well as CO or CO2 methanation and...Due to coexisting of H2, CO2 and H2O with CO in hydrogen-rich gas produced from methanol reforming, the selective CO oxidation is companied with the side reactions of H2 oxidation, as well as CO or CO2 methanation and reverse water-gas shift reaction（RWGS）. This paper investigated the effects of the above side reactions on the selective CO oxidation over a 0.5% Pt/Al2O3 monolithic catalyst. The results showed that after 50% H2 is added into the reactants, the highest CO conversion is only 98.3% at 180℃ when the feed molar ratio of O2 to CO is 1, and the corresponding outlet CO concentration is 180×10 -6 . Adding 50% H2 into the reactants accelerate CO oxidation at low temperatures; the catalyst active reaction temperature window shifts down about 40℃ . CO produced from RWGS is 80×10 -6 at 200℃ indicating that the effect of RWGS on selective CO oxidation becomes obvious at temperatures higher than 200℃. On the other side, CO or CO2 methanation does not take place even at 300℃ under current conditions and has little effects on the selective CO oxidation.展开更多
A series of Ni-CeO2 catalysts were prepared by co-precipitation method with Na2CO3, NaOH, and mixed precipitant （Na2CO3：NaOH; 1：1 ratio） as precipitant, respectively. The effect of the precipitants on the catalyti...A series of Ni-CeO2 catalysts were prepared by co-precipitation method with Na2CO3, NaOH, and mixed precipitant （Na2CO3：NaOH; 1：1 ratio） as precipitant, respectively. The effect of the precipitants on the catalytic performance, physical and chemical properties of Ni-CeO2 catalysts was investigated with the aid of X-ray diffraction （XRD）, Bmmaner-Emmett-Teller method （BET）, Fou- rier-transform infrared spectroscopy （FT-IR）, thermogravimetry （TG）, and H2-TPR characterizations. The Ni-CeO2 catalysts were exam- ined with respect to their catalytic performance for the reverse water-gas shift reaction, and their catalytic activities were ranked as： Ni-CeO2-CP （Na2CO3：NaOH=I：I）〉Ni-CeO2-CP（Na2CO3）〉Ni-CeO2-CP（NaOH）- Correlating to the characteristic results, it was found that the catalyst prepared by co-precipitation with mixed precipitant （Na2CO3：NaOH; 1：1 ratio） as precipitant hadthe most amount of oxygen vacancies accompanied with highly dispersed Ni particles, which made the corresponding Ni-CeO2-CP（Na2CO3：NaOH=I： 1） catalyst exhibit the highest catalytic activity. While the precipitant of Na2CO3 or NaOH resulted in less or no oxygen vacancies in Ni-CeO2 catalysts. As a result, Ni-CeO2-CP（Na2CO3） and Ni-CeO2-CP（NaOH） catalysts presented poor catalytic performance.展开更多
文摘Due to coexisting of H2, CO2 and H2O with CO in hydrogen-rich gas produced from methanol reforming, the selective CO oxidation is companied with the side reactions of H2 oxidation, as well as CO or CO2 methanation and reverse water-gas shift reaction（RWGS）. This paper investigated the effects of the above side reactions on the selective CO oxidation over a 0.5% Pt/Al2O3 monolithic catalyst. The results showed that after 50% H2 is added into the reactants, the highest CO conversion is only 98.3% at 180℃ when the feed molar ratio of O2 to CO is 1, and the corresponding outlet CO concentration is 180×10 -6 . Adding 50% H2 into the reactants accelerate CO oxidation at low temperatures; the catalyst active reaction temperature window shifts down about 40℃ . CO produced from RWGS is 80×10 -6 at 200℃ indicating that the effect of RWGS on selective CO oxidation becomes obvious at temperatures higher than 200℃. On the other side, CO or CO2 methanation does not take place even at 300℃ under current conditions and has little effects on the selective CO oxidation.
基金supported by the National Key Research and Development Program of China(2020YFB0606404)National Natural Science Foundation of China(21991092,22272195,U2003123,U1910203).
基金Project supported by Natural Science Foundation of Zhejiang Province(Y4110220)Foundation of the Zhejiang Provincial Department of Education(Y200908245)Foundation of the Dinghai Academy of Science and Technology(201006)
文摘A series of Ni-CeO2 catalysts were prepared by co-precipitation method with Na2CO3, NaOH, and mixed precipitant （Na2CO3：NaOH; 1：1 ratio） as precipitant, respectively. The effect of the precipitants on the catalytic performance, physical and chemical properties of Ni-CeO2 catalysts was investigated with the aid of X-ray diffraction （XRD）, Bmmaner-Emmett-Teller method （BET）, Fou- rier-transform infrared spectroscopy （FT-IR）, thermogravimetry （TG）, and H2-TPR characterizations. The Ni-CeO2 catalysts were exam- ined with respect to their catalytic performance for the reverse water-gas shift reaction, and their catalytic activities were ranked as： Ni-CeO2-CP （Na2CO3：NaOH=I：I）〉Ni-CeO2-CP（Na2CO3）〉Ni-CeO2-CP（NaOH）- Correlating to the characteristic results, it was found that the catalyst prepared by co-precipitation with mixed precipitant （Na2CO3：NaOH; 1：1 ratio） as precipitant hadthe most amount of oxygen vacancies accompanied with highly dispersed Ni particles, which made the corresponding Ni-CeO2-CP（Na2CO3：NaOH=I： 1） catalyst exhibit the highest catalytic activity. While the precipitant of Na2CO3 or NaOH resulted in less or no oxygen vacancies in Ni-CeO2 catalysts. As a result, Ni-CeO2-CP（Na2CO3） and Ni-CeO2-CP（NaOH） catalysts presented poor catalytic performance.
