Ni/ZrO2 by dielectric barrier discharge plasma decomposition with improved activity and enhanced coke resistance for CO methanation

Abstract

CO methanation over supported Ni catalysts has recently attracted increasing attentions. However, the low temperature activity and stability of Ni catalysts still need to be improved. In this work, a dielectric barrier discharge (DBD) plasma decomposition of nickel nitrate was performed at atmospheric pressure and around 150 °C. Followed by the hydrogen reduction thermally at 500 °C, a highly dispersed Ni/ZrO2 catalyst with intensified Ni-ZrO2 interaction and significantly improved activity for CO methanation was obtained. The DBD plasma decomposed catalyst effectively promotes CO dissociation as well as further hydrogenation. In addition, more reactive atomic carbon is formed on the Ni active sites. Such carbon species can be quickly removed by H2 gasification, keeping the Ni surface clean. A better balance between CO dissociation and carbon gasification has been achieved with enhanced carbon resistance. Therefore the DBD plasma decomposed catalyst can remain active under lower H2/CO ratios, while the calcined catalyst needs higher H2/CO feed ratio to overcome the catalyst deactivation.