Methane dry reforming over hydrotalcite-derived Ni-Mg-Al mixed oxides: the influence of Ni content on catalytic activity, selectivity and stability

Ni-containing hydrotalcite-derived catalysts were prepared using different Ni loadings (from ca. 4 to 60 wt%) at the same M-II/M-III ratio equal to 3. The influence of the Ni content on the physico-chemical features of these catalysts was studied, as well as the influence of this parameter on their activity in dry reforming of methane at low to moderate temperatures. The characterization of materials showed that the catalysts' properties, such as reducibility, basicity, morphology, texture and crystallite size, were strongly influenced by the Ni content. Dry reforming of methane and direct methane decomposition experiments showed increasing methane conversion with increasing Ni content, as a consequence of increasing Ni particle size. CO2 conversion was found to be higher for the catalysts showing the highest total basicity. Carbon formation was higher for the catalysts prepared at the highest Ni loadings, thus pointing to reduced Ni content as a way of controlling carbon formation through methane decomposition.