The sol–gel autocombustion as a route towards highly CO(2)-selective, active and long-term stable Cu/ZrO(2) methanol steam reforming catalysts

The adaption of the sol–gel autocombustion method to the Cu/ZrO(2) system opens new pathways for the specific optimisation of the activity, long-term stability and CO(2) selectivity of methanol steam reforming (MSR) catalysts. Calcination of the same post-combustion precursor at 400 °C, 600 °C or 800 °C allows accessing Cu/ZrO(2) interfaces of metallic Cu with either amorphous, tetragonal or monoclinic ZrO(2), influencing the CO(2) selectivity and the MSR activity distinctly different. While the CO(2) selectivity is less affected, the impact of the post-combustion calcination temperature on the Cu and ZrO(2) catalyst morphology is more pronounced. A porous and largely amorphous ZrO(2) structure in the sample, characteristic for sol–gel autocombustion processes, is obtained at 400 °C. This directly translates into superior activity and long-term stability in MSR compared to Cu/tetragonal ZrO(2) and Cu/monoclinic ZrO(2) obtained by calcination at 600 °C and 800 °C. The morphology of the latter Cu/ZrO(2) catalysts consists of much larger, agglomerated and non-porous crystalline particles. Based on aberration-corrected electron microscopy, we attribute the beneficial catalytic properties of the Cu/amorphous ZrO(2) material partially to the enhanced sintering resistance of copper particles provided by the porous support morphology.