Catalytic and photocatalytic reactions of H2 + CO2 on supported Au catalysts

•Catalytic reaction between H2 and CO2.•Production of CO.•Electronic interaction between Au and oxides.•Photo-induced reaction of CO2.

The interaction and the reaction between H2 + CO2 have been investigated on supported Au catalysts. By means of infrared spectroscopy, the formation of formate species was detected. The reaction between H2 + CO2 occurred above 475–500 K. The main reaction pathway was the formation of CO. The catalytic efficiency of Au sensitively depended upon the nature of the support. Highest conversion of CO2 was found on Au particles dispersed on n-type oxides, TiO2, ZnO, and CeO2. Au deposited on insulating oxides exhibited much less activity. At higher pressure, at 8.5 atm, a small amount of CH4 and CH3OH were also produced. Illumination of the active catalysts induced the reaction even at room temperature resulting in the formation of CH4. The high activity of Au particles supported by n-type semiconducting oxides was ascribed to the electronic interaction between Au and oxides leading to the activation of CO2.

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