Comparative study on the reaction of methane over a ZnO bed in the absence and presence of CO 2

Abstract

The reaction of zinc oxide with methane in the absence and presence of CO 2 were theoretically and experimentally investigated using HSC Chemistry 5.1 software and a fixed bed reactor, respectively. In the absence of CO 2 at 1193 K, the reduction of ZnO was accompanied with methane cracking, and metallic zinc, CO, and H 2 were the main reaction products. This system could be utilized for the co-production of metallic zinc and synthesis gas, in which ZnO was a donor of oxygen. In the presence of CO 2, ZnO plays as a catalyst in the CO 2 reforming of methane and produces syngas with the average H 2/CO ratio of 0.88 at 1193 K, which was close to the total reaction theoretic value of 1. It was also found that higher temperature favored high CH 4 and CO 2 conversions. XRD technique was used to characterize the ZnO species. The result showed that there were no differences in the peak profiles of the XRD patterns of the ZnO powder obtained before and after passing the CH 4/CO 2 mixed gases for 6 h at 1193 K. It is suggested that ZnO functions as a catalyst according to the redox cycle and metallic zinc plays the role of intermediate product in this process.