Nano-CaO or CaCO3 is supposed to have high capacity of CO2 capture, better stability and also high reaction speed. This is mainly due to the reduction of diffusion stage of carbon capture. Nano-CaCO3 was synthesized and used for ICCU-DRM. The procedure is shown below, copied from (https://doi.org/10.1016/j.apcatb.2020.119734).
“Typically, the precursor solution of calcium (solution 1) was prepared by dissolving 2.3594 g (0.01 mol) of calcium nitrate tetrahydrate (99 %, Sigma-Aldrich) and 0.6 g of PVP (average MW = 40000, Aldrich) in an alcohol aqueous solution, composed of 100 mL of ethylene glycol (99.8 %, Sigma-Aldrich) and 20 mL of deionized water, at 40 °C. The precipitant solution (solution 2) was prepared by dissolving 1.6787 g (0.02 mol) of sodium bicarbonate (100 %, J.T. Baker) in 100 mL of ethylene glycol at 40 °C. Afterwards, solution 2 was slowly dropped into solution 1 in 1 h under vigorous stirring at 40 °C. The produced CaCO3 precipitate was collected by centrifugation, washed by deionized water for 3 times then by 2-propanol (100 %, VWR Chemicals) for 2 times, finally dispersed in 100 mL of 2-propanol by sonication.”
The authors further coated the nano-CaCO3 sorbents with ZrO2 using the following procedure (same reference as before):
“The above CaCO3 suspension was added into a CTAB-P123 solution (contains 0.4 g of cetyl trimethyl ammonium bromide (CTAB, 98–101 %, Merck), 10 mL of P123 (average MW = ∼ 5800, Sigma-Aldrich) aqueous solution (4 wt% in water) and 100 mL of 2-propanol). After stirring for 2 h at 30 °C, 3 mL of aqueous ammonia (25 wt%, VWR Chemicals) was added and stirred for further 2 h. Afterwards, a zirconium-alcohol aqueous solution (preparation: 1.8766 g of zirconium oxynitrate hydrate (99 %, Sigma-Aldrich), 50 mL of deionized water and 100 mL of 2-propanol were vigorously stirred at 80 °C for few hours until all zirconium precursors were dissolved and a white sol formed) was dropwisely added. After stirring for 24 h at 30 °C, the product was collected by centrifugation and washed by deionized water for 3 times. Then, the clean particles were aged in deionized water at room temperature for 24 h, filtered and dried at 60 °C in vacuum overnight. The as-prepared support was named as Ca@Zr.”
TEM-EDX results of the prepared dual functional materials are shown below (same reference as above):
