EFFECTS OF SUPPORT ON CARBON FORMATION AND GASIFICATION ON NICKEL DURING CARBON-MONOXIDE HYDROGENATION

Rates of carbon deposition during carbon monoxide hydrogenation at 325-450 degree C and of carbon removal by oxygen at 300-350 degree C on unsupported Ni, Ni/Al//2O//3, Ni/SiO//2, and Ni/TiO//2 were determined by in situ gravimetric measurements. Following an induction period, carbon deposits on these catalysts at very significant rates; the order of decreasing deposition rate is Ni/TiO//2, Ni/Al//2O//3, Ni, Ni/SiO//2. Rates of gasification of these deposits in oxygen decrease in the same order. The order of decreasing deposition rate is the same as for carbon monoxide dissociation and removal of carbidic carbon by reaction with hydrogen.