Manufacture of calcium-based sorbents for high temperature cyclic CO2 capture via a sol–gel process

Cyclic CO2 capture characteristics of a pellet derived from sol-gel CaO powder with Ca12Al14O33 support

“…However, the CO 2 capture capacity of the pellet remained relatively stable during the cyclic carbonation/calcination reactions: 0.52 and 0.43 g CO 2 /g sorbent during the first and fiftieth cycle, respectively. In the authors' previous study, CaO powder derived from a sol-gel process achieved a CO 2 capture capacity of 0.37 g CO 2 /g sorbent during the twentieth cycle under the same reaction conditions used in the current research [32]. This result indicates that the pellet exceeded its precursor in cyclic CO 2 capture performance.…”

“…The sol-gel CaO powder (denoted as SG CaO) was prepared according to the procedure in the authors' previous study [32]. The predetermined amounts of analytical reagent-grade metal nitrate tetrahydrate and citric acid monohydrate were added to distilled water at a water-to-metal ion molar ratio of 40 : 1 and a citric acidto-metal ion molar ratio of 1 : 1.…”

“…Recent studies have proposed a solgel process to synthesize calcium-based sorbents with high cyclic reactivity [25][26][27][28][29][30][31]. CaO powder prepared through the sol-gel process showed that well-dispersed particles with an average size of approximately 200 nm formed within the sorbent with CO 2 capture capacity of the powder at 0.51 g CO 2 /g sorbent during 20 th cycle [32].…”

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

“…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]. The sol-gel preparation route ensures a homogenous distribution between CaO and binder, resulting in a stable structure, and inhibits sintering during multi-cycle operation.…”

“…To our best knowledge, only one group has reported the synthesis of pure CaO [63] and CaO promoted with La [63,65,66] and Al [65] via the sol-gel auto-combustion synthesis route using citric acid as combustion agent. This paper adds to the current knowledge in the field by presenting a systematic investigation of the effect of the organic material used as combustion agent (citric acid, ethylene glycol and triethanolamine), the nature of the structural promoter (Zr, La, Mg, Al) and the CaO concentration in the mixed materials on the physicochemical characteristics and the CO 2 capacity and stability of the as synthesized sorbents in multiple carbonation/calcination cycles.…”