Mg(OH)2 for CO2 Capture from High-Pressure, Moderate-Temperature Gas Streams

Precombustion CO2 separation is considered to be the most efficient method of carbon removal for fossil fuels. Solid sorbents are promising for CO2 separation because of lower sensible heats, higher CO2 sorption capacities, and favorable adsorption/desorption temperatures. The work reported here continues an effort to develop a Mg­(OH)2-based sorbent that adsorbs CO2 at IGCC fuel gas temperatures of 150–200 °C and at 280 psig. One novelty of the sorbent is that the CO2 can also be released near 300 °C at 280 psig reducing downstream compression costs of CO2 capture and storage. This work details thermodynamic equilibrium data that illustrates the optimal regeneration temperature and pressure, Fourier transform infrared data that shows the adsorbed species on the surface of the sorbents, fixed-bed performance testing, and the effect of moisture on regeneration. Additional information on potential heat integration during regeneration is also reported. These findings further demonstrate the ability of the Mg­(OH)2 sorbent to capture CO2 from fuel gas streams in an IGCC plant efficiently.