LTA and FAU Zeolites as Water and CO₂ Sorbents for Sorption-Enhanced CO₂ Hydrogenation (SECO2H): Low-Pressure Sorption-Enhanced Methanol Synthesis as a Case Study

The selection of the zeolite used in a sorption enhanced CO 2 hydrogenation process (SECO 2 H) plays a decisive role in determining the extent of process intensification and the resulting product yields. This selection is governed by several key properties, including zeolite acidity, pore aperture, adsorption capacity, and the selective adsorption of the target reaction product. Among the zeolites investigated, namely 3 A, 4 A, 5 A (LTA framework), and 13X (FAU framework), the last one exhibited the highest CO 2 and H 2 O adsorption capacities. However, LTA-3A provided the highest selectivity and affinity towards H 2 O adsorption. H 2 O adsorption also appeared stronger than CO 2 adsorption, as complete H 2 O desorption and zeolite regeneration required more severe desorption conditions than those needed for CO 2 removal. Sorption-enhanced methanol synthesis (SEMS) was selected as the target reaction to evaluate the effect of these zeolites on CO 2 hydrogenation. Among all the materials studied, only LTA-3A provided a pronounced intensification of the process, increasing both CH 3 OH and CO yields due to its highly selective H 2 O adsorption. The SEMS experiments assisted by LTA-3A delivered yields above the conventional thermodynamic limits of the conventional process and outperformed reported values under comparatively mild operating conditions.