Reactivity Switch of Platinum with Gallium: from Reverse Water Gas Shift to Methanol Synthesis

24 January 2024, Version 1
This content is a preprint and has not undergone peer review at the time of posting.

Abstract

The development of efficient catalysts for the hydrogenation of CO2 to methanol using “green” H2 is foreseen to be a key step to close the carbon cycle. In this study, we show that small and narrowly distributed alloyed PtGa nanoparticles supported on silica, prepared via a surface organometallic chemistry (SOMC) approach, display notable activity for the hydrogenation of CO2 to methanol, reaching 7.2 mol h-1 molPt-1 methanol formation rate with a 54% intrinsic CH3OH selectivity. This reactivity sharply contrasts with what is expected for Pt, which favors the reverse water gas shift reaction, albeit with a poor activity (2.6 mol h-1 molPt-1). In situ XAS studies indicate that ca. 50% of Ga is reduced to Ga0 yielding alloyed PtGa nanoparticles, while the remaining 50% persist as isolated GaIII sites. The PtGa catalyst slightly dealloys under CO2 hydrogenation conditions and displays redox dynamics with PtGa-GaOx interfaces, responsible for promoting both CO2 hydrogenation activity and methanol selectivity. Further tailoring the catalyst interface by using a carbon support in place of silica enables to improve the methanol formation rate by a factor of ~5.

Keywords

CO2 hydrogenation
SOMC
Platinum-based catalyst
methanol synthesis

Supplementary materials

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Title
Reactivity Switch of Platinum with Gallium: from Reverse Water Gas Shift to Methanol Synthesis
Description
Supporting information
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