Tuning e-fuel selectivity in sorption-enhanced CO2 hydrogenation over In2O3/ZrO2: The effect of LTA and FAU zeolites

Abstract

The e-fuels synthesis via CO₂ hydrogenation and the Sorption Enhanced Reaction technology are captivating strategies for CO₂ utilization and the integration of renewable energy sources. This study focuses on enhancing the conversion of CO₂ over an In₂O₃/ZrO₂ catalyst by incorporating LTA zeolites (3A and 4A) and a FAU zeolite (13X). Key operational parameters, such as temperature (T), Gas Hour Space Velocity (GHSV), type of zeolite, and Zeolite: Catalyst mass ratio (Z/C), were systematically varied. LTA zeolites (3A and 4A) provided the highest CO₂ conversions. The introduction of a water-adsorbing solid into the reactor significantly altered the products yield and selectivity. While the selectivity towards CH₄, CH₃OH, and C₂H₆O appeared to lay on the type of zeolite, the selectivity towards CO remained unaffected. Zeolite 3A demonstrated the greatest enhancement in selectivity towards CH₄ and CH₃OH, whereas the synthesis of C₂H₆O was favored by zeolites 4A and 13X. The Zeolite:Catalyst mass ratio also played a crucial role in process performance, influencing both CO₂ conversion and product selectivity. Increasing this ratio improved CO₂ conversion and reduced CO selectivity under all operating conditions, while CH₄ selectivity increased. However, the selectivity toward CH₃OH and C₂H₆O exhibited an anomalous and complementary behavior. While a maximum was observed for DME, a minimum was registered in methanol production, suggesting a dependency of the dehydration reaction kinetics on the amount of water produced during the reaction.