Mechanistic study of carbon dioxide hydrogenation over Pd/ZnO-based catalysts: the role of palladium-zinc alloy in selective methanol synthesis

Angew Chem Int Ed Engl. 2021 May 13. doi: 10.1002/anie.202103087. Online ahead of print.ABSTRACTPd/ZnO catalysts show good activity and high selectivity to methanol during catalytic CO 2 hydrogenation. The palladium-zinc alloy phase has been usually considered as the active phase, though mechanistic studies under operando conditions have not been conducted to verify this. Here, we report a detailed mechanistic study under realistic conditions of methanol synthesis, using in situ and operando X-ray absorption spectroscopy, X-ray powder diffraction and time-resolved isotope labeling experiments coupled with FTIR spectroscopy and MS analysis. Palladium-zinc alloy-based catalysts, prepared through reduction of a heterobimetallic Pd II Zn II acetate bridge complex, and which do not contain zinc oxide or any PdZn/ZnO interface, produce mostly carbon monoxide. The palladium-zinc phase is, therefore, principally associated with the formation of carbon monoxide, and does not provide the active sites required to produce methanol from the direct hydrogenation of carbon dioxide. Instead, we show that the presence of a zinc oxide phase, in contact with a palladium-zinc phase, is essential for efficient production of methanol.PMID:33983683 | DOI:10.1002/anie.202103087

Source: Angewandte Chemie - May 13, 2021 Category: Chemistry Authors: Maxim Zabilskiy Vitaly L Sushkevich Mark A Newton Frank Krumeich Maarten Nachtegaal Jeroen A van Bokhoven Source Type: research