Significant Roles of Surface Hydrides in Enhancing the Performance of Cu/BaTiO_2.8H_0.2 Catalyst for CO₂ Hydrogenation to Methanol

Abstract

Tuning the anionic site of catalyst supports can impact reaction pathways by creating active sites on the support or influencing metal‐support interactions when using supported metal nanoparticles. This study focuses on CO2 hydrogenation over supported Cu nanoparticles, revealing a 3‐fold increase in methanol yield when replacing oxygen anions with hydrides in the perovskite support (Cu/BaTiO2.8H0.2 yields ~146 mg/h/gCu vs. Cu/BaTiO3 yields ~50 mg/h/gCu). The contrast suggests that significant roles are played by the support hydrides in the reaction. Temperature programmed reaction and isotopic labelling studies indicate that BaTiO2.8H0.2 surface hydride species follow a Mars van Krevelen mechanism in CO2 hydrogenation, promoting methanol production. High‐pressure steady‐state isotopic transient kinetic analysis (SSITKA) studies suggest that Cu/BaTiO2.8H0.2 possesses both a higher density and more active and selective sites for methanol production compared to Cu/BaTiO3. An operando high‐pressure diffuse reflectance infrared spectroscopy (DRIFTS)‐SSITKA study shows that formate species are the major surface intermediates over both catalysts, and the subsequent hydrogenation steps of formate are likely rate‐limiting. However, the catalytic reactivity of Cu/BaTiO2.8H0.2 towards the formate species is much higher than Cu/BaTiO3, likely due to the altered electronic structure of interface Cu sites by the hydrides in the support as validated by density functional theory (DFT) calculations.

Tuning Selectivity of CO2 Hydrogenation via Support Composition Modification Adjusted the Activity Reduction of H Species over Ce1–xPrxO2−δ-Supported Metal (Ru, Rh) Nanoclusters

“…Meanwhile, in situ DRIFTS results showed that the trend of CO species formation and decay was highly consistent with the trend of surface CO 2 . Considering that the trend of CO species formation and decay was significantly different from that of CH 4 , we believed that CO did not participate in the RDS generated by CH 4 . ,, According to previous reports, in the carbonyl pathway, the hydrogenation of CO was the RDS of the reaction . Therefore, the carbonyl pathway was not the main reaction pathway for the CO 2 hydrogenation on Ru/CPO-10.…”