Silicon assisted synthesis of high-purity Ca3Al2O6 carrier towards scale-up of Ca-based carbon dioxide capture materials

Aluminium-stabilized calcium-based materials are currently an excellent solution for capturing CO2 directly from industrial flue gas. However, there is still no report on the technology of low-cost and large-scale assembly of Ca3Al2O6 and CaO. In this study, we innovatively put forward a silicon-assisted strategy to facilely synthesize high-purity Ca3Al2O6 and evaluate its cyclic performance for stabilizing uptake CO2 after assembly. With regard to the Si/Al ratio of 0.2, Ca3Al2O6 was prepared selectively among 850-900 degrees C, with only 5.2% CaO residually. The introduction of silicon inhibited the formation of Ca5Al6O14 by-products and the mechanism of silicon at the calcium-aluminum interface was also explained by systematic characterization. The Ca3Al2O6 modified sorbent with simple assembly showed extremely high cycle stability improvement compared with the pure precipitated calcium carbonate derived CaO. These works provide technical guidance for the industrial scale-up of the rational design of Al-stabilized calcium-based adsorption materials.