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

Abstract

• H 2 O v /CO 2 adsorption selectivity for FAU-13X and LTA-4A zeolites up to 250 °C and different flow configurations. • The presence of H 2 O v promotes a significant fall in the CO 2 uptake. • FAU-13X zeolite is more selective for H 2 O v /CO 2 removal than LTA-4A. • DSE model applies successfully for adsorption data of CO 2 , H 2 O v , and H 2 O v +CO 2 on both zeolites. CO 2 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 CO 2 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 °C. To study the competitive adsorption of water in the presence of CO 2 and the corresponding adsorption kinetics, essential for SERP, experiments using combinations of water vapor and CO 2 were carried out in the range of 100–250 °C by using an Intelligent Gravimetric Analyzer (IGA) integrated with an infrared (IR) CO 2 analyzer. The results showed that FAU-13X zeolite presents a significant adsorption selectivity for water vapor over CO 2 , 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 CO 2 at 100 °C and 250 °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 CO 2 catalytic conversion.