Study on CO₂ Hydrogenation on Methanol Cu-In₂O₃-MgO-Based Catalysts

The increasing need to mitigate CO₂ emissions and develop sustainable chemical processes has driven intensive research on CO₂ hydrogenation to methanol. This work investigates novel Cu–In–Mg–Al based catalysts synthesised by co-precipitation and systematically evaluates their physicochemical properties and catalytic performance. The catalysts were characterised through X-ray diffraction (XRD), nitrogen adsorption–desorption (BET), hydrogen temperature-programmed reduction (H₂-TPR), and scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy (SEM–EDX). Catalytic tests were carried out in a fixed-bed reactor at 225–300 °C and 35 bar, with performance assessed in terms of CO₂ conversion, methanol selectivity, and space–time yield (STY). The study focused on the role of copper, the effect of In and Mg promoters, the impact of metal loading, and the influence of contact time. Results confirm copper as the essential active phase for CO₂ activation, while In and Mg enhance methanol selectivity by suppressing competing reactions. An optimal balance between metal loading and contact time was found to be critical to maximise methanol productivity. Finally, the best-performing formulation (30Cu–3.5In–15Mg) was compared with a commercial Cu/ZnO/Al₂O₃ catalyst. While the commercial catalyst exhibited higher CO₂ conversion and productivity, the promoted catalyst provided superior selectivity towards methanol, demonstrating the beneficial role of In and Mg promoters. This study highlights the potential of multicomponent Cu-based systems for CO₂-to-methanol applications and provides insights into catalyst design strategies aimed at improving efficiency, selectivity, and stability.