Effect of Zn promoter on catalytic activity and stability of Co/ZrO2 catalyst for dry reforming of CH4

Abstract

The effects of Zn addition on the catalytic performance of CoZn(x)/ZrO2 catalyst (x=0–3wt.%) in the dry reforming of methane were investigated. The presence of an appropriate amount of Zn produced a noticeable improvement in the catalytic performance. The addition of Zn to a Co/ZrO2 catalyst, at a ratio of up to 2wt.%, had a positive effect on the catalyst stability, whereas further addition beyond this threshold had the opposite effect. The XPS and TGA results indicated that the surface Co species on both the Co/ZrO2 and CoZn(2)/ZrO2 catalysts were oxidized by the CO2. However, the oxidation rate of the two catalysts differed; the Co/ZrO2 catalyst oxidized faster and to a greater degree than the CoZn(2)/ZrO2 catalyst. Therefore, the Co/ZrO2 catalyst was rapidly deactivated due to the loss of active sites by the oxidation, whereas the Zn−promoted catalyst exhibited a more stable catalytic activity as the oxidation of Co was prevented by formation of a Co−Zn alloy.