Selective adsorption of water vapor in the presence of carbon dioxide on hydrophilic zeolites at high temperatures

CO2 valorization by chemical recycling into useful chemicals and alternative fuels is often accompanied by the production of water as by-product, which limits thermodynamically the CO2 conversion and has a negative effect on catalyst activity. Water removal from the reaction medium through the intensified sorption enhanced reaction process (SERP) is an effective way to significantly increase the conversion of reactants and the selectivity of desired products. We have previously revealed that FAU-13X and LTA-4A zeolites have adequate water adsorption capacity in the temperature range of 100-250 degrees C. To study the competitive adsorption of water in the presence of CO2 and the corresponding adsorption kinetics, essential for SERP, experiments using combinations of water vapor and CO2 were carried out in the range of 100-250 degrees C by using an Intelligent Gravimetric Analyzer (IGA) integrated with an infrared (IR) CO2 analyzer. The results showed that FAU-13X zeolite presents a significant adsorption selectivity for water vapor over CO2, which is 1.2 times higher compared to LTA-4A. In addition, water vapor is adsorbed on FAU-13X 46 and 20 times (on average) more than CO2 at 100 degrees C and 250 degrees C, respectively. The double stretched exponential model was applied to determine the kinetic parameters, which represent key data in modeling, design, and simulation of sorption enhanced reaction processes involving CO2 catalytic conversion.

Automated summary

FAU-13X zeolite exhibits a significant adsorption selectivity for water vapor over CO2, with adsorption capacities 46 and 20 times higher than CO2 at 100 degrees C and 250 degrees C respectively, which is essential for sorption enhanced reaction processes involving CO2 catalytic conversion.