Methane coupling by membrane reactor. Quarterly technical progress report, December 25, 1994--March 24, 1995

Research efforts during this quarter concentrated on two issues. The first issue is related to the chemistry of oxygen conducting materials that could be used as dense membranes in the membrane reactors. Mixed oxides of La, Sr, Fe, Ce, Yb etc., were synthesized, characterized and studied for their catalytic activity towards the oxidative coupling of methane. Heavy metal oxides of lanthanum, strontium and iron, which form good oxygen conductors, showed very poor methane coupling activity. Perovskites of the Strontium-Cerium-Yitribium series showed moderate activity for methane coupling. These could be potential candidates for dense membrane synthesis, since they also have moderate oxygen conduction properties. The second area of research focus was the development of a radial flow catalytic membrane reactor in which methane coupling was carried out over a catalyst that was deposited inside the pores of a ceramic porous membrane. Catalytic results from the high temperature oxidative coupling of methane in these radial flow membrane reactors are presented in this report. By exploring the reactor performance in membranes of pore diameters of 2.0{mu}m, 0.2{mu}m, and 0.02{mu}m, the effect of the diffusional regime on the methane. coupling activity was demonstrated. The smallest pore diameter membranes exhibited lowest hydrocarbon selectivities