Defence Weixin Meng: "Engineering Reaction Pathways in CO₂ Hydrogenation over Iron-Based Catalysts"
Promotors: first promotor: Prof J. Xie, second promotor: prof dr ir H.J. Heeres
Abstract: CO 2 hydrogenation to fuels and chemicals via the modified Fischer-Tropsch synthesis (CO 2 -FTS) is a promising route for CO 2 utilization, but controlling product selectivity remains challenging due to the coupling of the reverse water-gas shift (RWGS) and Fischer-Tropsch synthesis (FTS) reactions. This thesis systematically explored the key parameters governing the interplay between the reverse water gas shift (RWGS) and Fischer-Tropsch synthesis (FTS) activities over the carbon-supported Fe-based catalysts, including thermodynamic constraints, CO 2 conversion, Fe nanoparticle size, carbon support hydrophobicity, K promotion and zeolites incorporation. The results show that RWGS dominates at low CO 2 conversion, while FTS becomes dominant above the RWGS equilibrium. Larger Fe nanoparticles (> 8 nm) promote carburization and enhance long-chain hydrocarbon selectivity. Catalyst support hydrophobicity and potassium promotion significantly affect RWGS activity and suppress undesired methanation. Furthermore, zeolite topology governs tertiary reactions such as cracking, oligomerization, and aromatization, enabling control over product distribution. Overall, this work provides fundamental insights into controlling the RWGS-FTS interplay and contributes to the rational design of efficient Fe-based catalysts for the selective conversion of CO 2 into long-chain hydrocarbons.