CO₂ Hydrogenation to Methanol: Impact of Calcination Temperature on CuMn/Al₂O₃ Catalyst Morphology and Performance

This work demonstrates the synthesis of a highly active copper-based catalyst (CuMn/Al₂O₃) for CO₂ hydrogenation using the solution combustion synthesis (SCS) approach. The synthesized catalysts were calcined at 400 °C (CMA 400) and 600 °C (CMA 600) to investigate the influence of the calcination temperature on the catalyst physiochemical properties and CO₂ hydrogenation performance. In addition, the fabricated catalysts were thoroughly characterized by various analytical tools including SEM, XRD, XPS, BET, and H2-TPR. ICP-OES was used to determine the elemental compositions of the fresh, calcined, and leached CMA catalysts. The results suggest that CMA 400 and CMA 600 attain a highly porous structure and rough surface morphology, with agglomerated and irregularly shaped particles. However, the porosity of CMA 600 was higher than that of CMA 400, whereas BET analysis suggests that CMA 400 has a larger surface area. The CO₂ hydrogenation performance of these catalysts was also investigated in a high-pressure fixed-bed reactor under various conditions. The results show that CMA 400 attains a higher CO₂ conversion with better methanol selectivity and yield at moderate conditions. However, CMA 600 shows more CO selectivity.