Effect of PdIn bimetallic particle formation on CO2 reduction over the Pd–In/SiO2 catalyst

• Pd–In/SiO2 has a 100% CO selectivity for CO2 hydrogenation at atmospheric pressure.
• PdIn bimetallic nanoparticles were formed by H2 reduction.
• PdIn phase weakens CO adsorption and increases barrier of CO hydrogenation.
• PdIn phase suppresses CH4 formation and results in high CO selectivity.

A Pd–In/SiO2 catalyst was prepared by the wet impregnation method and used for CO2 reduction at atmospheric pressure. The catalyst was shown to have 100% selectivity toward CO with no detectable CH4 formation. In order to understand the high CO selectivity of Pd–In/SiO2, a detailed catalyst characterization in combination with the DFT study was conducted and compared with that over the Pd/SiO2 catalyst. The XRD and TEM analyses indicate the formation of the PdIn bimetallic nanoparticles on Pd–In/SiO2 after H2 reduction. The unique catalytic property of Pd–In/SiO2 was attributed to the formation of the bimetallic particles. Characterizations including H2 chemisorption and DRIFT and DFT modeling show that the formation of PdIn bimetallic nanoparticles reduces the activity toward H2 dissociative adsorption, weakens CO binding on the surface and increases the barrier of CO hydrogenation, suppressing the further hydrogenation beyond CO.

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