Characterization of new potassium-based solid sorbents prepared using metal silicates for post-combustion CO2 capture

Potassium-based sorbents prepared using metal oxides as supports or additive materials are commonly applied in fast fluidized bed reactors for post-combustion CO2 capture. However, they have some disadvantages in terms of regeneration properties. To overcome these drawbacks, novel potassium-based sorbents, herein termed KAS, KCS, and KZS, prepared using aluminum silicate, calcium silicate, and zirconium silicate, respectively, were developed in this study. Unlike potassium-based sorbents prepared using metal oxides, the new sorbents exhibited high CO2 capture capacities (90-96 mg CO2/g sorbent) and excellent regeneration ratios of 90% or more during multiple tests, even at a the low regeneration temperature of 200 °C. These improved results were achieved because KHCO3 alone is formed during CO2 sorption without any by-product formation, and there is no loss of the active material (K2CO3) during preparation. Thus, metal silicates can be used to prepare potassium-based solid sorbents for CO2 capture at low temperatures.