Post-Combustion and Pre-Combustion CO2 Capture Solid Sorbents

Combustion of fossil fuels is one of the major sources of the greenhouse gas CO2. Pressure swing adsorption/sorption (PSA/PSS) and temperature swing adsorption/sorption (TSA/TSS) are some of the potential techniques that could be utilized for removal of CO2 from fuel gas streams. It is very important to develop sorbents to remove CO2 from fuel gas streams that are applicable for a wide range of temperatures. NETL researchers have developed novel CO2 capture sorbents for low, moderate, and high temperature applications. A novel liquid impregnated solid sorbent was developed for CO2 removal in the temperature range of ambient to 60 °C. The sorbent is regenerable at 60 – 80 °C. The sorbent formulations were prepared to be suitable for various reactor configurations (i.e., fixed and fluidized bed). Minimum fluidization gas velocities were also determined. Multi-cycle tests conducted in an atmospheric bench scale reactor with simulated flue gas indicated that the sorbent retains its CO2 sorption capacity with a CO2 removal efficiency of approximately 99% and was unaffected by presence of water vapor. The sorbent was subsequently commercially prepared by Süd Chemie to determine the viability of the sorbent for mass production. Subsequent testing showed that the commercially-synthesized sorbent possesses the same properties as the lab-synthesized equivalent. An innovative solid sorbent containing mixture of alkali earth and alkali compounds was developed for CO2 removal at 200 – 315°C from high pressure gas streams suitable for IGCC systems. The sorbent showed very high capacity for CO2 removal from a gas streams containing 28% CO2 at 200 °C and at 20 atm during a lab scale reactor test. This sorbent can be regenerated at 20 atm and at 375 °C utilizing a gas stream containing steam. High pressure enhanced the CO2 sorption process. Bench scale testing showed consistent capacities and regenerability. A unique high temperature solid sorbent was developed for CO2 capture at temperatures of 500 – 700°C. Bench scale testing of the sorbent yielded very high CO2 capture capacity from a gas stream containing 10% CO2, 30% H2, 15% H2O, and 25% He. Regeneration of the sorbent is possible at 800 – 900 °C