LEAD-OXIDE MAGNESIA AEROGEL CATALYSTS FOR THE OXIDATIVE COUPLING OF METHANE WITH NITROUS-OXIDE

A series of PbO-MgO aerogels differing by their atomic Pb/Mg ratios we re tested at 720 degrees C for methane coupling using nitrous oxide to ethane and ethylene. The best catalyst (Pb/Mg = 0.5) gave a C-2+ over all selectivity of 69%, a high activity (at W/F = 0.03 g s cm(-3)) and a good stability with time-on-stream. A kinetic study showed that the reaction is of the Rideal-Eley type with nitrous oxide reacting in th e adsorbed phase. Other supports such as Al2O3, ZrO2, TiO2 and SiO2 we re used and the activities recorded agreed well with the basicity of t he catalyst, PbO-SiO2 being totally inactive: MgO > ZrO2 > Al2O3 > TiO 2 > > > SiO2.