Accelerating Water Removal through Porosity-Engineered PDVB for Enhanced CO2 Hydrogenation to Methanol

Abstract

Cu-based catalysts are promising for CO2-to-methanol conversion, but their activity and stability are usually compromised by the accumulation of byproduct water. Although physically mixing hydrophobic additives with Cu-based catalysts can facilitate water removal, how to regulate the water-removal kinetics in this process, as well as its impact on the reaction kinetics of CO2 hydrogenation to methanol, remains insufficiently understood. Herein, by modifying the polydivinylbenzene (PDVB) with porosity, we regulate the surface hydrophobicity of its mixture with a layered double hydroxide (LDH)-derived CuZnAlMg catalyst, thereby enhancing the water removal kinetics on the mixed catalyst surface. In contrast to nonporous PDVB, porous PDVB, with a substantially higher surface area and abundant mesopores, effectively creates additional H2O transfer channels. This facilitates rapid water removal, which in turn inhibits the oxidation of Cu nanoparticles and ensures the re-exposure of oxygen-vacancy active sites for sustained catalysis. Furthermore, water removal also accelerates the formation and subsequent hydrogenation of intermediates for higher activity. Consequently, a high space-time yield of methanol of 519.89 gMeOH kgcat–1 h–1 and a CO2 conversion rate of 26.35% are achieved at 5 MPa and 260 °C. The mixed catalyst exhibits excellent stability over 200 h of continuous operation. This work offers a simple yet robust strategy for regulating catalyst hydrophobicity toward efficient CO2 hydrogenation to methanol.