A Low Cost, High Capacity Regenerable Sorbent for Post Combustion CO2 Capture

TDA Research , Inc (TDA) is developing a low cost , high capacity CO2 adsorbent and demonstrating its technical and economic viability for post-combustion CO2 capture for existing pulverized coal-fired power plants under a 3-year DOE funded project.  TDA uses an advanced physical adsorbent to selectively remove CO2 from the flue gas.  The sorbent exhibits a much higher affinity for CO2 than N2 , H2O or O2.  The sorbent binds CO2 more strongly than common adsorbents , providing the chemical potential needed to remove the CO2. However , because CO2 does not form a true covalent bond with the surface sites , the regeneration can be carried out with only a very small energy input (4.9 kcal per mol of CO2) compared to amines (14.2 kcal/mol CO2). We demonstrated the sorbent’s efficacy through multiple cycles for removing CO2 from coal derived flue gas and the sorbent achieved a stable capacity.  The presence of acid gases such as SO2 and NOx (80 and 200 ppmv , respectively) and water vapor up to 15% vol. caused no adverse effect on the CO2 capacity.  The regeneration of the sorbent and the recovery of CO2 and its pressurization can be achieved by several approaches , including temperature and vacuum swing.  Our preliminary analysis showed that TDA’s CO2 capture process will reduce plant efficiency only by 21.7% (compared to 30% reduction for amine scrubbers) while providing 90% capture. A detailed techno-economic analysis using Aspen PlusTM software is being conducted in collaboration with University of California Irvine to estimate the impact of the TDA’s CO2 capture system on plant efficiency and cost of electricity. We will present the results from our Year 1 and Year 2 work at the AIChE meeting.