Lewis Acid Strength of Interfacial Metal Sites Drives CH3OH Selectivity and Formation Rates on Cu-Based CO2 Hydrogenation Catalysts

CH3OH formation rates in CO2 hydrogenation on Cu-based catalysts sensitively depend on the nature of the support and the presence of promoters. In this context, Cu nanoparticles supported on tailored supports (highly dispersed M on SiO2; M=Ti, Zr, Hf, Nb, Ta) were prepared via surface organometallic chemistry, and their catalytic performance was systematically investigated for CO2 hydrogenation to CH3OH. The presence of Lewis acid sites enhances CH3OH formation rate, likely originating from stabilization of formate and methoxy surface intermediates at the periphery of Cu nanoparticles, as evidenced by metrics of Lewis acid strength and detection of surface intermediates. The stabilization of surface intermediates depends on the strength of Lewis acid M sites, described by pyridine adsorption enthalpies and C-13 chemical shifts of -OCH3 coordinated to M; these chemical shifts are demonstrated here to be a molecular descriptor for Lewis acid strength and reactivity in CO2 hydrogenation.

Automated summary

The presence of Lewis acid sites on Cu nanoparticles supported on tailored supports enhances CH3OH formation rate in CO2 hydrogenation, likely originating from the stabilization of formate and methoxy surface intermediates. The strength of Lewis acid M sites, characterized by pyridine adsorption enthalpies and C-13 chemical shifts of -OCH3 coordinated to M, serves as a molecular descriptor for Lewis acid strength and reactivity in CO2 hydrogenation.