(396a) Investigation of Sorbents for Warm CO2 Capture by Pressure Swing Adsorption

Integrated gasification combined cycle with CO₂ capture and sequestration (IGCC-CCS) emerges as a promising method for achieving higher energy efficiency and better emission control compared with the traditional pulverized coal plant. But the current CCS technology, especially the commercially-available solvent-based CO_­2 capture process is energy intensive which makes the IGCC process unaffordable. To achieve DOE’s goal concerning IGCC-CCS, which requires a 90% CO₂capture with less than 10% increase in cost of electricity, some energy-efficient capture process needs to be developed.

Recent research conducted in our group indicates that the efficiency of IGCC can be improved if a warm CO₂ capture process based on solid sorbent can be employed. However, no commercial sorbents or sorption process exists for this purpose. To address this problem, in this paper, we present a sorbent material and an 11-step pressure swing adsorption (PSA) process which could be potentially used for warm CO₂ capture in IGCC plant. The metal oxide based sorbent material developed in our lab shows a stable working capacity, fast kinetics, and good cyclic stability in the temperature range of interest. Then, we propose an 11-step PSA process containing three pressure equalization steps and one high pressure purge step which can ensure a large H₂ recovery and lower compression work for CO₂ stream. The PSA process simulation is based on the measured performance specifications of the sorbent. In addition, the relationship between H₂ recovery and CO₂ capture is explored and improved by adjusting key operating parameters. Finally, the PSA model is integrated into an IGCC process simulation within Aspen Plus in order to determine optimal operating conditions and the power plant efficiency. A sensitivity analysis is conducted to suggest necessary material properties for improvement, which could potentially provide direction for next-step experimental work on sorbent development.