Open AccessSilica-Supported PdGa Nanoparticles: Metal Synergy for Highly Active and Selective CO2-to-CH3OH Hydrogenation
Author(s) -
Scott R. Docherty,
Nat Phongprueksathat,
Erwin Lam,
Gioh,
Оlga V. Safonova,
Atsushi Urakawa,
Christophe Copéret
Publication year - 2021
Publication title -
jacs au
Language(s) - English
Resource type - Journals
ISSN - 2691-3704
DOI - 10.1021/jacsau.1c00021
Subject(s) - x ray absorption spectroscopy , catalysis , selectivity , nanoparticle , formate , absorption spectroscopy , materials science , fourier transform infrared spectroscopy , spectroscopy , heterogeneous catalysis , infrared spectroscopy , chemistry , inorganic chemistry , photochemistry , nuclear chemistry , chemical engineering , nanotechnology , organic chemistry , physics , quantum mechanics , engineering
The direct conversion of CO 2 to CH 3 OH represents an appealing strategy for the mitigation of anthropogenic CO 2 emissions. Here, we report that small, narrowly distributed alloyed PdGa nanoparticles, prepared via surface organometallic chemistry from silica-supported Ga III isolated sites, selectively catalyze the hydrogenation of CO 2 to CH 3 OH. At 230 °C and 25 bar, high activity (22.3 mol MeOH mol Pd -1 h -1 ) and selectivity for CH 3 OH/DME (81%) are observed, while the corresponding silica-supported Pd nanoparticles show low activity and selectivity. X-ray absorption spectroscopy (XAS), IR, NMR, and scanning transmission electron microscopy-energy-dispersive X-ray provide evidence for alloying in the as-synthesized material. In situ XAS reveals that there is a dynamic dealloying/realloying process, through Ga redox, while operando diffuse reflectance infrared Fourier transform spectroscopy demonstrates that, while both methoxy and formate species are observed in reaction conditions, the relative concentrations are inversely proportional, as the chemical potential of the gas phase is modulated. High CH 3 OH selectivities, across a broad range of conversions, are observed, showing that CO formation is suppressed for this catalyst, in contrast to reported Pd catalysts.