High performance CO₂ capture at elevated temperatures by using cenospheres prepared from solid waste, fly ash

Cenospheres (CS) are spherical shaped inorganic frameworks present in with fly ash which is generated from coal-fired thermal power plants. These spherical structures were functionalized with imidazole and amine moieties to capture CO₂ selectively from flue gases at elevated temperature. The functionalized CS have shown a high selectivity for CO₂ adsorption (4.68 mmol g^-1) over N₂ (0.46 mmol g^-1) at 333 K/1 bar from a simulated flue gas (0.15 CO₂ and 0.85 N₂, v%) composition of thermal power plants. When the moisture content reached to 30 vol% the adsorption capacity of CS materials was reduced to 20 vol% as compared to dry flue gas. The functionalized CS can be used repeatedly for 50 cycles without losing its adsorption capacity. The cost estimate for CO₂ capture by using the proposed adsorption system would be $12.01/ton of CO₂ which is lower as compared to amine absorption system and zeolite-based adsorption system reported in the literature. The CS materials are prepared from solid wastes reduce the cost of production and their large scale manufacturing is technically feasible to capture CO₂ from industrial flue gases efficiently in near future.