Combination of CO2 Reforming and Partial Oxidation of Methane over NiO/MgO Solid Solution Catalysts

Abstract

To overcome the explosions that can occur during the partial oxidation of methane, the latter exothermic reaction is coupled with an endothermic one, namely, the CO2 reforming of CH4. These combined reactions have been carried out over NiO/MgO solid solution, NiO/Al2O3, and NiO/SiO2 catalysts. About 90% conversion of CH4 and about 98% selectivities to CO and H2 were obtained at 790 °C and a GHSV(gas hourly space velocity) of 90 000 cm3 g-1 h-1 (O2/CO2/CH4 = 14.5/26.9/58.6), over a reduced NiO/MgO solid solution catalyst. Almost no change in activity and selectivity occurred during 50 h of reaction. Compared to the reduced NiO/MgO, the reduced NiO/SiO2 and NiO/Al2O3 catalysts provided lower activities and stabilities. The effects of the reaction temperature, space velocity, and feed gas composition for a ratio CH4/(CO2 + 2O2) = 1 were investigated. The increase in O2 in the feed gas resulted in a higher conversion of CH4, but the apparent conversion of CO2 passed through a maximum. The CH4 conversion decreased with increasing space velocity, while during the partial oxidation, because of the hot spots, it would have increased. This means that the coupling can, indeed, control the thermal behavior of the reactor.