Atomic layer deposited zinc promoted copper catalysts for carbon dioxide hydrogenation to methanol: Influence of support

Abstract

Copper promoted with zinc is an active catalyst for carbon dioxide hydrogenation to methanol, a reaction relevant to carbon capture and utilization technologies. Previous work showed that inverse zinc-on-copper catalysts on zirconia supports, where zinc(II) is added via atomic layer deposition (ALD), are more active and selective in this reaction than copper-on-zinc catalysts on zirconia. This work continues exploring the inverse zinc-on-copper catalysts by varying the support, comparing zirconia support with alumina, titania and niobia, and with various combinations of the ceria-zirconia-lanthana mixed oxide family. Catalyst characterization was made with elemental analysis, temperature-programmed reduction, temperature-programmed desorption of carbon dioxide, nitrous oxide pulse titration, and transmission electron microscopy. Activity was measured in a fixed-bed flow reactor at 450–550 K. ALD of Zn(II) acetylacetonate gave a similar areal number density of ca. two zinc per square nanometer on all tested supports. Zinc promotion systematically increased the methanol production rate. Among the tested catalysts, the zinc-on-copper on zirconia support remained the most active, with other catalysts from the ceria-zirconia-lanthana mixed oxide family giving almost as good results.