Regenerable magnesium-based sorbent for high-pressure and moderate-temperature CO2 capture: Physicochemical structures and capture performances

Abstract The CO 2 capture for a kind of magnesium-based sorbent from commercially available magnesium-based materials was carried out for CO 2 capture under high pressures (up to 2.5 MPa) and moderate temperatures (200–400 °C). Simultaneously, the evolutions of its physicochemical structures during cyclic capture were analyzed by an X-ray Diffractometer (XRD), a thermo-gravimetric analyzer (TGA), a scanning electron microscope coupled with an electron detection scanning (SEM/EDS), and a surface area and pore structure analyzer. For this sorbent with an unique active component of Mg(OH) 2 , its active components from the pure Mg(OH) 2 compound and the initial calcination and followed hydroxylation of magnesium-based materials were carbonated to respectively produce crystalline and amorphous MgCO 3 during CO 2 capture. The hydroxylation importantly altered relatively small pores into relatively large pores in the sorbent, and the hydroxylation step was necessary, favorable and critical for a higher CO 2 capture capacity of the sorbent. Although H 2 S in the feed gas could cause an important decreasing in its CO 2 capture capacity, it hardly affected its cyclic stability. As a whole, the prepared sorbent was suitable for the CO 2 removal regardless of H 2 S presence under high pressures and moderate temperatures.