A Carbide Slag-Based, Ca 12 Al 14 O 33 -Stabilized Sorbent Prepared by the Hydrothermal Template Method Enabling Efficient CO 2 Capture

Calcium looping is a promising technology to capture CO 2 from the process of coal-fired power generation and gasification of coal/biomass for hydrogen production. The decay of CO 2 capture activities of calcium-based sorbents is one of the main problems holding back the development of the technology. Taking carbide slag as a main raw material and Ca 12 Al 14 O 33 as a support, highly active CO 2 sorbents were prepared using the hydrothermal template method in this work. The effects of support ratio, cycle number, and reaction conditions were evaluated. The results show that Ca 12 Al 14 O 33 generated effectively improves the cyclic stability of CO 2 capture by synthetic sorbents. When the Al 2 O 3 addition is 5%, or the Ca 12 Al 14 O 33 content is 10%, the synthetic sorbent possesses the highest cyclic CO 2 capture performance. Under harsh calcination conditions, the CO 2 capture capacity of the synthetic sorbent after 30 cycles is 0.29 g/g, which is 80% higher than that of carbide slag. The superiority of the synthetic sorbent on the CO 2 capture kinetics mainly reflects at the diffusion-controlled stage. The cumulative pore volume of the synthetic sorbent within the range of 10–100 nm is 2.4 times as high as that of calcined carbide slag. The structure of the synthetic sorbent reduces the CO 2 diffusion resistance, and thus leads to better CO 2 capture performance and reaction rate.