Exploiting oxidative coupling of methane performed over La2(Ce1−xMgx)2O7−δ catalysts with disordered defective cubic fluorite structure

The oxidative coupling of methane reaction to produce C2 compounds was studied using La2(Ce1−xMgx)2O7−δ catalysts with disordered defective cubic fluorite structures, varying the Mg content (0.0 ≤ x ≤ 1.0), CH4/O2 ratio, temperature, and WHSV. The partial substitution of Ce by Mg in the structure modified the morphology, adjusted the reducibility, stabilized the Ce3+ species, and provided different concentrations of basic sites, which allowed a 42% increase in the yield of C2, with ethylene as the major product. The catalyst with 0.4 Mg content in the structure provided C2 selectivity of 52%, with CH4 conversion of 28%, even under conditions richer in O2. The highest selectivity to C2 (75%), with the highest selectivity to ethylene (39.1%), was achieved using a CH4 : O2 ratio of 8 : 1. In addition, it was possible to operate at milder temperatures (650 °C), with satisfactory CH4 conversion (22%) and C2 selectivity (54%). By decreasing the space velocity, the CH4 conversion and C2 selectivity decreased with an ethylene/ethane ratio of 3. The inhibitory effects of H2O and CO2 were observed at lower space velocity.