Enhanced Efficiency of CO2 Hydrogenation To Produce Methanol over Mn-Doped SrTiO3-Supported Copper Catalysts

Abstract

Methanol production via CO₂ hydrogenation has garnered significant attention, with Cu-based catalysts emerging as a promising and practical candidate due to their affordability and superior catalytic abilities. Nonetheless, efficiently converting CO₂ into methanol with these catalysts poses a substantial challenge. Herein, we have developed highly dispersed copper-based catalysts over Mn-doped SrTiO₃ perovskite-type oxide supports for efficient methanol production from CO₂ hydrogenation. It was demonstrated that proper Mn doping significantly induced the generation of oxygen vacancies and medium-strength basic sites and facilitated active copper species dispersion. Significantly, the as-constructed Cu-based catalyst featuring a Mn/(Mn + Ti) ratio of 0.15 displayed an impressively high methanol formation rate of 4.02 g_MeOH g_Cu^–1 h^–1 at 220 °C and 3.0 MPa, surpassing those for most state-of-the-art Cu-based catalysts. Through various structural characterizations and in situ diffuse reflectance infrared Fourier transform spectroscopic analysis, it was discovered that the enhanced catalytic efficiency of the catalyst was attributed to the synergistic effect between multiple active sites (i.e., Cu⁰/Cu⁺ sites, oxygen vacancies, and medium-strength basic sites), effectively promoting H₂ dissociation and CO₂ adsorption/activation, as well as reaction intermediates, facilitating CO₂ hydrogenation via both formate intermediate and reverse water–gas shift reaction-derived CO intermediate pathways and consequently enabling a significant enhancement in methanol production.