Intensification of CO2 hydrogenation by in-situ water removal using hybrid catalyst-adsorbent materials: Effect of preparation method and operating conditions on the RWGS reaction as a case study

• Reverse water-gas shift was explored as a case study of CO 2 hydrogenation processes. • Process was intensified through in situ water removal using hydrophilic adsorbents. • Mechanically mixed catalyst-adsorbents outperformed bifunctional materials. • Adding Cu to 13X zeolite altered textural properties, reduced acidity, and H 2 O uptake. • An operating temperature of 250 °C was found optimum in the SE-RWGS process. Intensifying CO 2 hydrogenation reactions by in-situ water removal via hydrophilic adsorbents alongside the catalyst is an innovative approach that can drastically improve the performance of conventional processes whose yields are restricted by thermodynamics. Here, the sorption-enhanced (SE) reverse water-gas shift (RWGS) reaction was explored as a case study since it represents the starting point of all CO 2 hydrogenation processes. Hybrid materials containing both catalyst (Cu/UGSO) and hydrophilic adsorbent (13X zeolite) were conceived to investigate for the first time (i) the effect of preparation method (with major impact on physicochemical properties and performance) and (ii) main operating parameters affecting greatly the yields (temperature and catalyst/adsorbent ratio). A comparison between mechanically mixed catalyst-adsorbent and bifunctional materials (containing active metal, catalytic support, and adsorbent within the same particle) revealed that Cu presence decreased the adsorptive ability of bifunctional materials, due to the decrease of specific surface area and zeolite acidity. In contrast, mechanical mixtures allowed to fully preserve the assets of both adsorbent and catalyst, to significantly intensify the reaction. The catalyst-adsorbent mixture obtained by wet mixing offered the best results by minimizing the average distance between catalytic and adsorption sites. 250 °C was found optimum for a significant reaction rate and a non-negligible water adsorption capacity of 13X zeolite. The reaction thermodynamic barrier was found to be crossed for catalyst/adsorbent mass ratio lower than 1, the intensification leading to a significant increase in CO 2 conversion. The findings of this work are crucial for implementing this type of intensified process, which pushes the limits dictated by thermodynamic equilibrium, and provide information of high interest to guide future research on all SE processes of CO 2 valorization via catalytic hydrogenation.