Conversion of CO2 to chemicals is an attractive approach for decreasing the content of this greenhouse gas in the atmosphere while providing chemicals from waste. Conversion of CO2 to formic acid or formate is particularly interesting, being a valuable basic chemical and a liquid storage form of H2.(1) Only few heterogeneous catalysts are reported for this reaction (2) and there is very limited research exploring Ni-promoted hydrogenation of CO2/bicarbonates into formate, probably due to the fact that metallic Ni is easily oxidized to NiO, thus losing catalytic activity.(3) Taking benefit of the organometallic approach,(4) a foam-like, air-stable, Ni-based nanomaterial for CO2/bicarbonate hydrogenation into formate was developed.(5) This nanomaterial was simply prepared by hydrogenation of the [Ni(COD)2] complex in THF/EtOH without any stabilizer. It exhibited remarkable stability in air with an over two times higher catalytic activity than commercial Raney Ni catalyst in formate synthesis, at only 100°C, a significantly lower operation temperature compared to the 200-260°C previously reported. Deep characterization evidenced a core-shell structure with a surface layer predominantly composed of amorphous Ni(OH)2 covering metallic Ni sites. The adsorption of bicarbonates on the catalyst proved a kinetically relevant step in the reaction. The Ni-Ni(OH)2 interface appeared beneficial for the activation of CO2 and H2, thus leading to enhanced activities. This work reports a robust nickel-based nanomaterial that is a performant catalyst for CO2 hydrogenation to formate in mild conditions. It also contributes to the understanding of ‘structure-activity’ relationship in CO2 conversion.

Hydrogenation of CO2/bicarbonate to formate catalyzed by a Ni@Ni(OH)2 nanocatalyst

ACS Spring Meeting 2021

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