Application of amine infused hydrogels (AIHs) for selective capture of CO2 from H2/CO2 and N2/CO2 gas mixture

Abstract

This study presents an efficient amine infused hydrogels-based CO2 separation technology from H2/CO2 and N2/CO2 gas mixtures. The amine-infused hydrogels (AIHs) prepared by mixing aqueous amine solution with dried hydrogel particles were exposed to the gas mixtures in static condition, then the absorption capacity of AIHs along with the initial uptake rate were obtained from the experimental data. Although the concentration of amines was less than 30 wt% for aqueous solutions, it was increased up to 45 wt% for AIHs and the absorption capacity increased from 0.4630 to 0.5046 mol CO2/mol amine for N2/CO2 gas mixture. By varying the types of amines, the highest absorption capacity was obtained with the 45 wt% monoethanolamine AIHs (MEA-AIHs), 0.505 mol CO2/mol amine, as well as the initial uptake rate of 0.513 mmol CO2/min. Diethanolamine AIHs (DEA-AIHs) showed good absorption capacity close to the MEA-AIHs, but the initial uptake rate was low. Compared to those DEA-AIHs, MDEA-AIHs showed less absorption capacity, but higher initial uptake rate. The addition of piperazine (PZ) into the MDEA-AIHs did not improve the CO2 absorption performance, but its positive effect was confirmed for the aqueous solution. Moreover, the presence of NO in gas mixture proved to degrade the performance of AIHs with up to 26.7 % reduction in absorption. When applying AIHs for H2/CO2 gas mixtures, both the absorption capacity and initial uptake rate were increased significantly, possibly due to high CO2 concentration and high partial pressure. MEA-AIHs showed higher initial uptake rate, but MDEA-AIHs showed better absorption capacity. The obtained results in this work suggest that AIHs can be applicable for post-combustion capture as well as for CO2 capture for blue hydrogen production.