HYDROGEN-PRODUCTION VIA THE DIRECT CRACKING OF METHANE OVER SILICA-SUPPORTED NICKEL-CATALYSTS

We have investigated the catalytic cracking of methane as an alternati ve route for the production of hydrogen from natural gas. Nickel suppo rted on silica was found to be active for this reaction producing stoi chiometric amounts of hydrogen and carbon. SEM and TEM characterizatio n of the spent catalyst indicated that carbon deposits on the catalyst in the form of hollow cylindrical filaments, with a nickel particle l ocated on the tip of each filament. As a result, deactivation due to c arbon deposition does not occur until the carbon filaments begin to in terfere with each other and the silica surface, due to the spatial Lim itations of the pore structure of the catalyst. The deactivated cataly st can be fully regenerated by either oxidation in air or steam gasifi cation of the deposited carbon. Additional hydrogen is produced during the steam regeneration process. (C) 1998 Elsevier Science B.V.