在固体碱催化剂上甲烷氧化偶联反应的研究

INVESTIGATION OF THE OXIDATIVE COUPLING REACTION OF METHANE ON SOLID BASIC CATALYSTS

The effect of the acidity and basicity of supports on the oxidative coupling of methane using oxides of Li and Mn etc. as active components has been investigated. It was shown that the selectivity of C_2(C_2H_4 and C_2H_6) increased with the increase of the basicity of supports, and higher acidity results in non-selective oxidation to CO_x(CO, CO_2). Doping Li/MgO with Na achieved a 100% C_2 selectivity at 23.7% conversion of CH_4 in the first hour. ESR results indicate that there are three kinds of oxygen species on the surface of catalysts, O~-, O_2~- and O_(?)~- O~- was the active species which abstracts H from CH_4 to produce CH_(3.) and then C_(2.) O_2~- and O_.~- are the species which oxidize the CH_(3.) deeply to produce CO_x. When the catalyst is doped with Na, the selectivity of C_2 is increased owing to more O~-.