METHOXY MOBILITY AND METHANE FORMATION ON THE ALUMINA SUPPORT

The mobility of OCH3 and H and their reaction to form CH4 on alumina are analyzed by using the atom superposition and electron delocalization molecular orbital (ASED-MO) theory. Theoretical evidence is given that OCH3, which is known to spill over from supported Ni and Pt to the alumina support, moves as an anion, OCH3-, from one Al3+ site to another, paired with a proton which moves from one O2- site to another. The reaction of this heterolytically adsorbed pair to form CH4(g) is calculated to be more stabilizing than CH3OH(g) formation. Our findings provide a possible explanation for recent experimental observations of others regarding CO methanation over Ni/Al2O3 and Pt/Al2O3.