Partial oxidation of methane to CO and H2 over nickel and/or cobalt containing ZrO2, ThO2, UO2, TiO2 and SiO2 catalysts

The influence of different metal oxide supports (i.e. ZrO2, ThO2, UO2, TiO2 and SiO2) on the performance of Ni- and/or Go-containing catalysts [Ni and/or Co/MO2 mole ratio (where M = Zr, Th, U, Ti or Si) = 1.0] in the oxidative methane-to-syngas conversion at very low contact time (GHSV = 5.2 x 10(5) cm(3) g(-1) h(-1) at STP) has been investigated. The nickel-containing ZrO2, ThO2 and UO2 catalysts (with or without pre-reduction by hydrogen at 500 degrees C) showed good performance in the process; the order of their performance is NiO-ThO2 > NiO-UO2 > NiO-ZrO2. The NiO-TiO2 showed appreciable catalytic activity only after its reduction at 800 degrees C. However, this catalyst and the NiO-SiO2 catalyst showed poor performance in the process. These two catalysts are also deactivated very fast, mostly due to sintering of Ni and/or formation of catalytically inactive binary metal oxide phases by solid-solid reaction at the high catalyst calcination and/or catalytic reaction temperature. Although the Ni-containing ThO2, UO2 and ZrO2 catalysts showed good performance, carbon deposition on them during the process is fast. However, because of the addition of cobalt to these catalysts (with Co/Ni = 1.0), the rate of carbon deposition on them in the process is drastically reduced. This Co addition however resulted in a significant decrease in both the conversion and selectivity; the decrease in the selectivity was small. (C) 1998 Published by Elsevier Science Ltd. All rights reserved.