Networking SiO₂-Al₂O₃ and amines into robust and long-lasting molded sorbents for continuous CO₂ capture

Amine sorbents are well-known for their low regeneration energy when compared with aqueous amines, which makes them ideal for highly efficient CO₂ capture. However, their commercialization lags behind amine scrubbing, due to the lack of facile and feasible sorbent molding and continuous processing methods. In this work, Amine/SiO₂-Al₂O₃ molded sorbents were successfully built using AlOOH·H₂O as a cross-linking binder and SiO₂ as a porous material to support a series of amines. The adsorption capacity and mechanical strength were comprehensively considered by optimizing the microstructure of support. Such molded amine sorbents exhibited an adsorption capacity of 1.6 mmol·g⁻¹, which accounts for over 90 % of corresponding powder solid amine sorbents. Moreover, the mechanical strength can reach as high as 2.75 MPa, and the energy consumption is as low as 1.86 GJ/tCO₂, meeting the commercial requirement. Furthermore, a continuous two-column CO₂ removal system was built to test the long-term performance of molded amine sorbents for continually 100 cycles. The results showed that sorbents remained at 80 % adsorption capacity after 100 cycles in a 20 % H₂O/80 % N₂ atmosphere, and the strength and structure of SiO₂-Al₂O₃ supports did not change. The excellent performance of the system provides a feasible path to highly efficient and reliable carbon capture, promoting the realization of mitigating the global warming issue for the present.