CO2 hydrogenation to methanol over In2O3: Influence of catalyst synthesis methods

Abstract

The development of highly active and thermally stable catalysts for green methanol synthesis from CO₂ hydrogenation is critical for advancing sustainable renewable energy cycles. In this study, indium oxide (In₂O₃) catalysts were synthesized by co-precipitation, sol gel, and direct calcination methods, and their structure-activity relationships in CO₂ hydrogenation were systematically investigated. The co-precipitation-derived In₂O₃ catalyst achieved the highest CO₂ conversion (13.8 %) and methanol space–time yield (STY, 408 g_methanol h⁻¹ kg_cat⁻¹). In contrast, the sol-gel-derived In₂O₃ catalyst demonstrated excellent stability, retaining 90.7 % of its initial activity after 60 h of operation. The superior performance of co-precipitation-prepared In₂O₃ was attributed to its smaller particle size, larger surface area, higher oxygen vacancy concentration, enhanced H₂ dissociation ability, and superior CO₂ adsorption capacity. Meanwhile, the outstanding stability of the sol-gel-derived In₂O₃ was linked to its intrinsic hydrophobicity, which effectively suppressed sintering and minimized particle agglomeration during reactions. This study provides valuable insights into the rational design of efficient and durable In₂O₃-based catalysts for CO₂ hydrogenation, advancing the development of green methanol production processes.