(91b) High Capacity Regenerable Sorbent for Pre-Combustion CO2 Capture
AIChE Spring Meeting and Global Congress on Process Safety
Tuesday, March 23, 2010 - 2:30pm to 3:00pm
TDA is developing a novel sorbent that removes CO2 via physical adsorption from both synthesis gas, while the relatively strong affinity of the sorbent for CO2 enables effective operation at temperatures up to 300oC (well above the dew point of synthesis gas stream generated by most commercial gasifiers). However, because the sorbent and the CO2 do not form a true covalent bond, the energy needed to regenerate our sorbent (5.4 kcal per mol of CO2) is much lower than that observed for either chemical absorbents (e.g., 29.9 kcal/mol CO2 for sodium carbonate) or amine-based solvents (e.g., 14.2 kcal/mol CO2 for monoethanolamine). Our sorbent can be regenerated isothermally and CO2 can be recovered at pressure (~150 psia). Thus, the energy needed to regenerate the sorbent and compress the CO2 for sequestration is significantly lower than that for any technology reported to date. TDA's CO2 sorbent could be used to capture CO2 in a Integrated Gasification Combined Cycle (IGCC) power plant after the water-gas-shift (WGS) reaction when most of the carbon is in the form of CO2. The high surface area and favorable porosity of the sorbent also provide a unique platform to introduce additional functionality, such as active groups to catalyze the or to remove trace metals (e.g., Hg, As).
We carried out bench-scale evaluations of TDA's CO2 sorbent in both fixed-bed adsorber and a thermo gravimetric analyzer (TGA). The sorbent achieved high CO2 capacity, high removal efficiency and excellent durability. The sorbent showed stable performance in both these systems under simulated synthesis gas (44 cycles in the bench-scale flow system and over 1,644 cycles in the TGA). We also studied the effect of operating parameters like temperature, pressure, and cycle time on the sorbent performance. The results from our on-going sorbent evaluations will be presented at the meeting.