The solid amine absorption is considered to be the most promising technology for post-combustion CO2 capture in coal-fired power plants, but it still has problems such as high support synthesis cost and easy occurrence of CO2-induced chemical deactivation. Herein, we proposed a new environmentally friendly method, a calcium silicate hydrate (CSH) support with a pore volume of 3.0 cm3 g-1 derived from coal fly ash (CFA) was synthesized by solution precipitation with the assistance of azeotropic distillation, and then the CO2 adsorbents were prepared by impregnating polyethylenimine (PEI) into the pores of CSH, which also realized the in-situ utilization of CFA while achieving CO2 emission reduction from coal-fired power plants. The adsorption capacity of the prepared 60%PEI@CSH-0.1 could reach 197.9 mg g-1 and exhibited good cycle stability of only 1.68% attenuation after 10 cycles under inert gas desorption conditions. Even under realistic desorption conditions (at 150°C under 100% CO2), there was still an adsorption capacity of 94.19 mg g-1 after 10 cycles, which showed obvious advantages compared with commercial SiO2 supports (67.06 mg g-1). It has been confirmed that the CSH support promoted the conversion of primary amines to secondary amines in PEI molecules, and effectively inhibited the inactivation caused by the formation of urea linkages. Therefore, the PEI@CSH adsorbents provides a promising low-cost and high-efficiency way for post-combustion CO2 capture.

Novel PEI@CSH adsorbents derived from coal fly ash enabling efficient CO2 capture from coal-fired power plants

ACS Spring 2022

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