EFFECT OF OXIDIZING AND REDUCING GAS ATMOSPHERES ON THE IRON-CATALYZED FORMATION OF FILAMENTOUS CARBON FROM METHANOL

Iron-catalyzed formation of filamentous carbon from methanol was studi ed at 500-600-degrees-C by exposing iron wire to methanol partial pres sures of 1.33-300 kPa in the presence of added partial pressures of wa ter vapor, carbon dioxide, and hydrogen. Filamentous carbon formed fro m feedstreams containing only methanol, and this process was accompani ed by metal dusting corrosion. Addition of a sufficient water vapor pa rtial pressure prevented both carbon deposition and corrosion. The rol e of water vapor is viewed as being to maintain the iron surface in an oxide state, which is inactive for the catalytic formation of filamen tous carbon. Carbon dioxide was found to be a much less effective oxid ant than water vapor, while hydrogen did not prevent filamentous carbo n formation. Carbon deposition from methanol occurs under conditions w here it would not be expected from the equilibrium products of its gas -phase decomposition (CO, CO2, H2O, H-2, and CH4).