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

Methane was successfully converted to synthesis gas by oxidative refor ming 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. Additi onally, 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 perfor mance. In accordance with the results of Choudhary on this and other c atalysts, the syngas yield was found to deviate from the expected equi librium values. This may be attributed to the catalyst temperature bei ng 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 inclu sion of low steam feed rates resulted in stable operation (no deactiva tion and constant bed temperature). Decreasing the CH4/O-2 ratio resul ted in improved CH4 conversion while, contrary to the expected equilib rium trend, CO selectivity remained constant. When space velocity was increased from 200 000 to 500 000 h(-1), CH4 conversion and CO selecti vity remained unchanged, but both values decreased when space velocity was again lowered to 200 000 h(-1).