Carbon capture turned upside down: high-temperature adsorption & low-temperature desorption (HALD)

Abstract

Carbon capture & sequestration (CCS) could reduce CO₂ emissions from large fossil-fuel power plants on the short term, but the high energy penalty of the process hinders its industrial deployment. Moreover, the utility of nanoporous materials, known to be selective for the CO₂/N₂ separation, is drastically reduced due to the competitive adsorption with H₂O. Taking advantage of the power plant's waste heat to perform CCS while at the same time surmounting the negative effect of H₂O is therefore an attractive idea. We propose an upside-down approach for CCS in nanoporous materials, high-temperature adsorption & low-temperature desorption (HALD), that exploits the temperature-dependent competitive adsorption of CO₂ and H₂O. First, we provide a theoretical background for this entropy-driven behavior and demonstrate under what conditions competitive adsorption can be in favor of CO₂ at high temperature and in favor of H₂O at low temperature. Then, molecular simulations in all-silica MFI provide a proof of concept. The International Zeolite Association database is subsequently screened for potential candidates and finally, the most promising materials are selected using a post-Pareto search algorithm. The proposed post-Pareto approach is able to select the material that shows an optimal combination of multiple criteria, such as CO₂/H₂O selectivity, CO₂/N₂ selectivity, CO₂ uptake and H₂O uptake. As a conclusion, this work provides new perspectives to reduce the energy requirement for CCS and to overcome the competitive adsorption of H₂O.