HOMOLOGATION OF OLEFINS WITH METHANE ON TRANSITION-METALS

Alkylation of olefins using methane has been realized on transition metal catalysts. The main problem is to get methane dissociatively adsorbed together with an olefin. This is due to the difficult activation of the strong tetrahedral C-H bonds of methane. To react methane with an olefin, a reaction sequence is used consisting of three steps. First methane is dissociatively adsorbed between 600 and 800 K on a reduced transition metal catalyst. After cooling, an olefin is coadsorbed at a temperature between 300 and 400 K. Upon subsequent hydrogenation carbon-carbon bond formation occurs. The mechanism appears to be related to that occurring in the Fischer-Tropsch reaction. After hydrogenation the reaction cycle can be repeated. Methane addition to ethene, propene, and acetylene is demonstrated to occur using silica-supported ruthenium and cobalt catalysts. With (CH4)-C-13 it was shown that propane and butane are formed both by self-homologation of ethene and propene, respectively, as well as by methane incorporation. Carbon scrambling according to the metathesis reaction is very slow.