The Role of Chemisorbed Oxygen on Diamond Surfaces for the Dehydrogenation of Ethane in the Presence of Carbon Dioxide

摘要

Oxidized diamond played a significant role as an efficient support for a Cr_2O_3-loaded catalyst during the dehydrogenation of C_2H_6 to C_2H_4 in the presence of carbon dioxide at 923 K, giving a 22.5% C_2H_4 yield with a 87.7% C_2H_4 selectivity. The activity of the oxidized diamond-supported Cr_2O_3 catalyst in the presence of CO_2 was about 3 times higher than that in the absence of CO_2. The activity of the oxidized diamond-supported Cr_2O_3 catalyst increased with increasing CO_2 partial pressures. XPS analyses of the fresh and the reacted catalysts in the presence and absence of CO_2 revealed that CO_2 maintained the surface Cr_2O_3 at a higher-oxidation state than the reaction in the absence of CO_2. On the other hand, bulk of Cr_2O_3 was not reduced in either atmosphere.