Solid Solution Engineering via Zr Doping in the Pd/ZrInO x Catalyst Switches Reaction Pathways for Enhanced Methanol Production from CO2

Abstract The Pd/In2O3 catalyst is promising for CO2-to-methanol conversion, yet it is limited by poor stability and sluggish conversion of formate intermediates. Replacing the In2O3 support in Pd/In2O3 with an In2O3-based solid solution, such as ZrInOx, is an effective strategy to balance activity and stability. However, how the Zr species regulates the Pd/In2O3 catalyst, especially its effect on the reaction pathway, remains unclear. Herein, by introducing atomically dispersed Zr on the Pd/In2O3 catalyst, we demonstrate an electronic disparity strategy to tune the reaction pathway for efficient CO2-to-methanol production. Characterizations confirm that Zr promotes oxygen vacancy formation and enhances the dispersion of Pd nanoparticles. These enhance the electronic metal–support interaction between Pd and the support to accelerate the electron transfer from Pd to the support, thereby making the In sites more electron-rich and Pd more electron-deficient, as well as enhancing CO2 adsorption and H2 dissociation. Theoretical studies show that during the reaction, the In sites at the oxygen vacancy and Pd species work in synergy to induce cleavage of the C═O bond in CO2 and switch the formate pathway to the RWGS+CO* hydrogenation pathway. Consequently, the Pd/ZrInOx catalyst achieved an 18% CO2 conversion with 710 gMeOH kgcat–1 h–1 methanol space-time yield at 300 °C and 5 MPa. This work highlights the influence of the solid solution structure on the CO2 hydrogenation process.