Partial oxidation of methane to synthesis gas over oxidized diamond catalysts

Oxidized diamond (O-dia) acted as an excellent support material for the partial oxidation of methane to synthesis gas. The O-dia gave the best performance among the support materials of Ni- and Co-loaded catalysts for the partial oxidation of methane at a low temperature. A nickel (3 wt.%)/O-dia catalyst afforded a high CH4 conversion of 26.5% at a CH4 to O-2 ratio of 5 to give nearly a 1 to 2 ratio of CO and H-2 with selectivities of 70% at 873 K. Cobalt (3 wt.%)/O-dia catalyst exhibited a slightly lower catalytic activity than that of Ni (3 wt.%)/O-dia catalyst, where CH4 conversion was 23.0%. No change in the support was observed in the oxidation atmosphere at a high temperature. Carbon deposition of the catalyst surface in the reaction of CH4 was examined by thermogravimetric analyses. Carbon deposition occurred on the nickel (3 wt.%)/O-dia catalyst at below 923 K, and above this temperature no carbon deposition was seen. However, on the cobalt-loaded catalyst no carbon deposition was observed at any reaction temperature. (C) 2004 Elsevier B.V. All rights reserved.