Activation of methane by transition metal-substituted aluminophosphate molecular sieves

摘要

Aluminophosphate molecular sieves substituted with cobalt, manganese or iron and having the AlPO.sub.4 -34 or AlPO.sub.4 -5, or related AlPO. sub.4 structure activate methane starting at approximately 350° C. Between 400° and 500° C. and at methane pressures ≦ 1 atmosphere the rate of methane conversion increases steadily with typical conversion efficiencies at 500° C. approaching 50% and selectivity to the production of C.sub.2+ hydrocarbons approaching 100%. The activation mechanism is based on reduction of the transition metal(III) form of the molecular sieve to the transition metal(II) form with accompanying oxidative dehydrogenation of the methane. Reoxidation of the - transition metal(II) form to the transition metal(III) form can be done either chemically (e.g., using O.sub.2) or electrochemically.