Hydrophobic modification of SiO2-encapsulated In2O3 catalyst: Boosting efficient CO2 hydrogenation to methanol

Abstract

The targeted design and optimization of the catalyst structure to boost catalytic efficiency is of great significance in heterogeneous catalysis, especially for CO₂ hydrogenation. Herein, a catalyst comprising SiO₂-encapsulated In₂O₃ particles was prepared, whose performance in CO₂ hydrogenation to methanol was subsequently significantly advanced through modification of its external surface with organosilanes. Systematic characterizations confirm that the uniform dispersion of small In₂O₃ nanoparticles within SiO₂ directly improves the efficiency and stability. Importantly, moderate hydrophobic modification can promote desorption of polar molecules (H₂O and CH₃OH), thereby accelerating methanol synthesis during prolonged experiments while preserving the structural integrity of the encapsulated In₂O₃. Further mechanistic studies reveal that moderate hydrophobic modification causes an increase in the concentrations of key intermediates in the methanol synthesis pathway, particularly CH₃O*, which is primarily responsible for enhanced methanol productivity. This work provides valuable insights toward the rational design and performance modulation of catalysts for CO₂ hydrogenation.