High-performance ZnZrOx-supported CuNi catalysts for CO2 hydrogenation to methanol

Abstract

ZnZrO_x solid solutions have been extensively reported for methanol production from the hydrogenation of carbon dioxide (CO₂) on account of their high selectivity, prominent stability and sulfur tolerance. Herein, a series of ZnZrO_x supported-CuNi catalysts were fabricated using a liquid-phase reduction-deposition method and then utilized for CO₂ hydrogenation. The impact of the Cu : Ni molar ratio on the physicochemical properties of the catalysts and their CO₂ hydrogenation performance was systemically studied and discussed. The synchronous introduction of Cu and Ni into ZnZrO_x not only improved the BET-specific surface areas and the reducibility of the metallic species but also markedly increased the concentration of surface oxygen vacancies and the amount of CO₂ desorbed, thereby leading to excellent reactivity. Moreover, the CH₃OH space-time yield (STY) was positively correlated to the concentration of surface oxygen vacancies and the amount of desorbed CO₂. Because of the outstanding reducibility, high metal dispersion, superior CO₂ adsorption ability, sufficient surface oxygen vacancies, and the proper interaction between the metals and support, Cu₂Ni₁/ZnZrO_x achieved a CH₃OH selectivity close to 82% with a CO₂ conversion greater than 10% at 3.0 MPa, 15 000 mL g_cat⁻¹ h⁻¹ and 280 °C.