Selective Hydrogenation of CO<sub>2</sub> to Methanol over Si-Modified Cu/Zn/Zr Catalyst with ZrSiO<sub>4</sub> Spacer via the RWGS + CO-Hydro Pathway.

Abstract

The industrial application of copper-based catalysts is significantly hindered by the inherent tendency of Cu species to aggregate and sinter during the CO₂ hydrogenation processes. Herein, we tailored a remarkably efficient Si-modified Cu/Zn/Zr catalyst where the generated ZrSiO₄ species on the catalyst surface spatially separated the active Cu components. This structural modification effectively regulated both the exposed Cu surface area and the quantity and strength of strong basic sites. In addition, an in situ DRIFTS analysis revealed that the target reaction proceeded via the RWGS + CO-Hydro pathway. Compared with the silicon-free catalyst, the more produced intermediate *CO would be rapidly consumed by H spillover from the Cu sites. Under reaction conditions of 230 °C, 3.0 MPa, and 3000 mL·g^-1·h^-1, the Si-modified catalyst demonstrated a 19% increase in CO₂ conversion and a 42% rise in methanol selectivity versus the Cu/Zn/Zr catalyst, while demonstrating excellent stability, particularly the resistance to high-temperature sintering. The strategy in our work might provide a guideline of nonmetallic modification to improve the current industrial catalyst.