Isolation of Oxygen Formed during Catalytic Reduction of Carbon Dioxide Using a Solid Electrolyte Membrane
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- 作者：Shigeki Furukawa ; Masaki Okada ; and Yohichi Suzuki
- 刊名：Energy & Fuels
- 出版年：1999
- 出版时间：September 1999
- 年：1999
- 卷：13
- 期：5
- 页码：1074 - 1081
- 全文大小：188K
- 年卷期：v.13,no.5(September 1999)
- ISSN：1520-5029
文摘
We studied the separative recovery of oxygen formed during the hydrogenation of carbon dioxideusing a composite system consisting of yttria-stabilized zirconia (YSZ) membrane-equipped Agelectrodes as a pump and a nickel/zeolite catalyst to initiate the hydrogenation of carbon dioxide.The methanation of carbon dioxide proceeded efficiently in the presence of the nickel/zeolitecatalyst even at 873 K, the lowest functional temperature at which YSZ has ionic conductivity.Carbon dioxide conversion and methane yield reached 100% and 80%, respectively, at H2/CO2 =10, space velocity < 6200 h-1, and 873 K. Carbon dioxide was adsorbed by the crystal structureof the zeolite even at 873 K, and methanation of the adsorbed carbon dioxide (CO2 ad) proceededby the following one-step reaction: CO2 ad + 3H2 
CH4 + H2O. The rate constant of methanationwas estimated to be 1.6 × 10-2 cm3 g-cat-1 s-1 for the pseudo-first-order reaction. Electrochemicalisolation of oxygen formed during hydrogenation of carbon dioxide was carried out undergalvanostatic conditions. It was assumed that the oxygen was converted to water by the nickel/zeolite catalyst and then transported through the YSZ electrolyte after the water was ionized.We assumed that the oxygen was not formed by the dissociation of carbon dioxide directly on thecathode electrode. It appeared that the charge-transfer process was the rate-determining stepfor isolation of oxygen on the cathode electrode in the presence of the nickel/zeolite catalyst.
CH4 + H2O. The rate constant of methanationwas estimated to be 1.6 × 10-2 cm3 g-cat-1 s-1 for the pseudo-first-order reaction. Electrochemicalisolation of oxygen formed during hydrogenation of carbon dioxide was carried out undergalvanostatic conditions. It was assumed that the oxygen was converted to water by the nickel/zeolite catalyst and then transported through the YSZ electrolyte after the water was ionized.We assumed that the oxygen was not formed by the dissociation of carbon dioxide directly on thecathode electrode. It appeared that the charge-transfer process was the rate-determining stepfor isolation of oxygen on the cathode electrode in the presence of the nickel/zeolite catalyst.