NONOXIDATIVE METHANE COUPLING OVER CO-PT NAY BIMETALLIC CATALYSTS/

Methane activation and coupling of the CHx species formed from methane into higher hydrocarbons over NaY, Pt/NaY, Co/NaY, Co-Pt/NaY and Co-P t/Al2O3 have been compared. Co-Pt/NaY and C0-Pt/Al2O3 showed exception ally high yields (100%) referred to the adsorbed CHx species and high selectivity in the formation of C-2+ hydrocarbons (83.6 and 99.6%, res pectively) in the two-step reaction using 523 K for chemisorption and 523 K for hydrogenation. However, the amount of CHx is four-fold highe r on Co-Pt/NaY than Co-Pt/Al2O3. The synergistic effect can be interpr eted by insertion of Co into Pt inside the zeolite cages which causes a preferential coupling of CHx species vs. its hydrogenation into meth ane. Separate experiments carried out on the removal of CHx species wi th deuterium show that deep dissociation of methane does not occur on bimetallic catalyst and the weakly bonded CHx species can easily parti cipate in chain building reaction on the surface.