TDA is developing a novel sorbent based PSA process that removes CO2
via physical adsorption from synthesis gas. The relatively strong affinity of the sorbent to CO2
enables effective operation at temperatures up to 300o
C (well above the dew point of synthesis gas stream generated by commercial gasifiers). However, because the sorbent and the CO2
do not form a true covalent bond, the energy needed to regenerate TDAâs 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). TDAâs sorbent can be regenerated isothermally and CO2
can be recovered at pressure (as high as 150 psia). Thus, the energy needed to regenerate the sorbent and compress the CO2
for sequestration is significantly lower than that for any other technology reported to date. The high surface area and favorable porosity of the sorbent also provides a unique platform to introduce additional functionality, such as active groups to catalyze the water-gas-shift (WGS) reaction or to remove trace metals (e.g., Hg, As). Hence, TDAâs CO2
sorbent could be used to do a warm gas capture of CO2
above the dew point of the synthesis gas in an Integrated Gasification Combined Cycle (IGCC) power plant. TDA's pre-combustion CO2
capture system achieves a net plant efficiency of 34% on a coal high heating value basis when operated on bituminous coal, which is significantly higher than that can be achieved with the SelexolTM
scrubber at 31.6% (state-of-the-art pre-combustion carbon capture technology).
In a current DOE sponsored project, TDA is carrying out field tests with the warm gas CO2 capture unit integrated with WGS catalyst at 10 cfm scale. In this paper we present the results from the 8-bed PSA cycle performance in the field test with real synthesis gas.