Enhanced CO2 hydrogenation to methanol over CuZn nanoalloy in Ga modified Cu/ZnO catalysts

- Ga-containing Cu-ZnO can greatly promote methanol synthesis from CO2 hydrogenation.
- ZnO and Ga-spinel create electronic heterojunction which helps the reduction of ZnO.
- Highly active CuZn bimetallic nanoparticles offer catalytic sites for the reaction.
- A correlation between Zn0 content in CuZn with catalytic performance is demonstrated.

With the introduction of Ga3+ into Cu/ZnO catalyst precursors, a series of catalysts have been prepared using a simple co-precipitation method and tested as catalysts for the synthesis of methanol from CO2 hydrogenation. It is found that the presence of a small amount of Ga3+ can facilitate thermal deep reduction of ZnO support to Zn atoms under hydrogen prior to catalysis; hence, a highly active CuZn bimetallic nanoparticle offering catalytic sites is generated. The effect of Ga3+ incorporation is attributed to the formation of Ga-containing spinel, ZnGa2O4 structure, which creates electronic heterojunction with excess ZnO phase to account for the facilitated reduction of Zn2+ to Zn0 to form CuZn when in contact with Cu nanoparticle. A correlation between Zn0 concentration in the CuZn alloy nanoparticle to the catalytic performance can thus be clearly demonstrated, which shows CO2 conversion and methanol selectivity can be significantly improved by increasing the Zn0 content in these hetero-junctioned catalysts.

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