With the aim to synthesize an inexpensive and high-stable sorbent for CO2 capture processes, an industrial waste-product derived from coal-fired power plant, the so-called coal fly ash (CFA) cenospheres, was employed as inert supporting material. The CaO-based sorbent derived from CFA cenospheres (mainly composed of mullite and quartz) was prepared via a solution-based citric acid method. The obtained slurry was decomposed at 500 °C in air for 2 h. From the XRD results the CaO-CFA500 sorbent was mainly composed of Ca12Al14O33 (mayenite) and Ca(OH)2 along with trace of γ-Al(OH)3 and CaCO3 and starting SiO2. A further air-heating at 900 °C was conducted because the CO2 sorbent is submitted at high temperature for regeneration. The CaO-CFA900 sorbent was made of free-CaO and two crystalline calcium-alumino-silicate phases, namely gehlenite (Ca2Al2SiO7) and anorthite (CaAl2Si2O8). The optimized mesopore size particles belonging to CaO-CFA900 was reflected in a high stability over multiple cycles of carbonation/calcination. The initial CO2 capture capacity of the sorbent was 0.33 g CO2 g−1 sorbent, which was about three times the value of pure CaO (0.11 g CO2 g−1 CaO), and reduced to 0.22 g CO2 g−1 sorbent after 20 cycles remaining then stable over 200th cycles. From the present results it can be argued that CaL process could be easily scalable by re-using a coal-fired plant waste-product. © 2019 Elsevier B.V.

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