OXIDATIVE REFORMING OF METHANE TO SYNGAS OVER A NIO-CAO CATALYST

Methane was successfully converted to synthesis gas by oxidative reforming over a reduced NiO-CaO catalyst first prepared by Choudhary et al. [1]. In order to compare this work with previously reported results, the effect of space velocity and temperature was investigated. Additionally, the lifetime of the catalyst was tested with both a dry and a wet feed, as well as the influence of CH4/O-2 ratio on catalyst performance. In accordance with the results of Choudhary on this and other catalysts, the syngas yield was found to deviate from the expected equilibrium values. This may be attributed to the catalyst temperature being higher than the measured bulk gas temperature. Lifetime tests (500 degrees C for 50 hours and 700 degrees C for 20 hours) showed that the catalyst slowly lost activity and selectivity. In contrast, the inclusion of low steam feed rates resulted in stable operation (no deactivation and constant bed temperature). Decreasing the CH4/O-2 ratio resulted in improved CH4 conversion while, contrary to the expected equilibrium trend, CO selectivity remained constant. When space velocity was increased from 200 000 to 500 000 h(-1), CH4 conversion and CO selectivity remained unchanged, but both values decreased when space velocity was again lowered to 200 000 h(-1).