Zn Loading Effects on the Selectivity of PdZn Catalysts for CO2 Hydrogenation to Methanol
Naomi Lawes, Kieran J. Aggett, Louise R. Smith, Thomas J. A. Slater, Malcolm Dearg, David Morgan, Nicholas F. Dummer, Stuart H. Taylor, Graham J. Hutchings, Michael Bowker
Abstract
Abstract PdZn/TiO 2 catalysts have been investigated for the hydrogenation of CO 2 to methanol. Varying the ratio of Pd and Zn using TiO 2 as a support has a dramatic effect on catalytic performance. Chemical vapour impregnation was used to produce PdZn alloys on TiO 2 and X-ray diffraction, X-ray photoelectron spectroscopy, and scanning transmission electron microscopy revealed changes in the structure at varying total PdZn molar ratios. Compared to monometallic Pd/TiO 2 , introducing a low loading of Zn drastically changes product selectivity. When Pd is alloyed with Zn above a total Zn/Pd = 1 molar ratio, methanol selectivity is improved. Therefore, for enhanced methanol productivity, it is crucial for the Zn loading to be higher than that required for the stoichiometric formation of the 1:1 β-PdZn alloy. Graphical Abstract