HYDROPHILIC ZEOLITE SORBENTS FOR IN-SITU WATER REMOVAL IN HIGH TEMPERATURE PROCESSES

An attractive approach to reduce anthropogenic emission of carbon dioxide (CO2) would be to valorize it into value-added products (e.g. alcohols or dimethylether) by chemical recycling. However, in most of these important reactions, water is produced as a byproduct that limits CO2 conversion thermodynamically and can lead to the deactivation of catalysts. Water removal in sorption-enhanced reaction process (SERP) would allow the overcoming of these drawbacks and several zeolites (SOD, LTA, and FAU) have been selected to assess their potential to adsorb water in-situ at high temperatures. This work aims to study the water adsorption capacity and kinetics in a large temperature range of 25-250 degrees C and evaluate the potential of the selected adsorbents for in-situ water removal in the reverse water gas shift (RWGS) reaction. For all zeolites, the water uptake showed an important decrease at higher temperatures but the capacity at 250 degrees C was still significant. While the poor adsorption kinetics of SOD limit its use, FAU-13X powder gave better results than LTA-4A, which were confirmed by a more important increase of CO concentration at the exit of the reactor for the RWGS reaction. Transient adsorption data obtained in this study were fitted by a double stretched equation and the kinetic constants were determined. These results are essential to model and design an efficient SERP process and determine the optimal reaction conditions.