Sol–gel-derived, CaO-based, ZrO2-stabilized CO2 sorbents

Solid sorbents for in-situ CO 2 removal during sorption-enhanced steam reforming process: A review

“…At high temperature atomic excitation allows the local migration of oxygen atoms from CaO toward the adsorbed CO 2 leading to its mineralization into carbonate around CaO particles; chemically the mineralization of CO 2 also implies the breaking of one covalent bond in the CO 2 molecule [24]. Typical optimal carbonation/regeneration parameters and details for different CaO-based sorbents are summarized in Table 1 [25][26][27][28][29][30][31][32][33][34][35][36][37]. The carbonation process of CaO is typically operated at 600-750°C at atmospheric pressure.…”

Improving the stability of synthetic CaO-based CO 2 sorbents by structural promoters

“…Although a high initial capacity is important in order to minimize the amount of sorbent circulating between the two reactors, maintaining or recovering this high capacity after multiple cycles, plays an equally important role. Different approaches have been applied to improve the cyclic stability of the sorbents, including thermal pre-treatment [47,48], incorporation of inert thermally resistant materials in the structure of CaO [49][50][51][52][53][54][55][56] and reactivation through water or steam hydration [57,58]. Different synthesis methods have also been employed in order to improve the stability of CaO, including precipitation, dry or wet mixing, flame spray pyrolysis and several modified sol-gel routes [49,51,53,[59][60][61][62][63].…”

Sol–gel-Derived Synthetic CaO-Based CO2 Sorbents Incorporated with Different Inert Materials

“…The best CaO-Al 2 O 3 sorbent containing 91 wt % CaO had a CO 2 capture capacity of 0.51 g CO 2 /g sorbent after 30 cycles under mild conditions (carbonation at 750°C in 40% CO 2 /N 2 for 20 min, calcination at 750°C in pure N 2 for 20 min), 45 whereas the best CaO-ZrO 2 containing about 70 wt % CaO showed a capture capacity of 0.34 g CO 2 /g sorbent after 90 cycles under other conditions (carbonation at 800°C in 50% CO 2 /N 2 for 5 min, calcination at 800°C in pure N 2 for 15 min). 29 Recently, we prepared CaO-Ca 9 Al 6 O 18 (or Ca 3 Al 2 O 6 ) sorbents via the hydrolysis of aluminum isopropoxide followed by addition of calcium precursors. 21 The best CaO-Ca 9 Al 6 O 18 with 90 wt % CaO displayed a capacity of 0.59 g CO 2 /g sorbent after 35 cycles (carbonation at 650°C in 15% CO 2 /N 2 for 30 min, calcination at 800°C in pure N 2 for 10 min).…”