A novel method for the preparation of CO2 sorption sorbents with high performance

A novel method for the synthesis of solid amine sorbents integrated into alumina-extraction from fly ash (FA) has been developed. The products, PEI-FA type sorbents, exhibit improved sorption performance and can be produced with a reasonable cost. Precursors for making these solid amine sorbents include a solution of silicate species, and a predefined amount of CO2-philic polyethylenimine (PEI). Samples of PEI-FA were prepared by a novel method termed as “Wet Support Impregnation” (WSI). The CO2 sorption capacities of these samples were measured using a thermogravimetric analyzer (TGA). The effects of sorption temperature, raw material concentrations and PEI loading on CO2 sorption capacity were also investigated. The results show that these sorbents are suitable for the capturing of CO2 at low temperatures with a highest sorption capacity of 145.0 mg-CO2/g-sorbent at 90 °C under 10% CO2 in N2, which is higher than those using the same precursors reported in the literatures. This can be attributed to the fact that WSI enables more amine to be loaded onto the supporting material than the conventional wet impregnation method does. More importantly, the silicate solution used as one of the precursors can be derived directly from fly ash, an industrial waste. This means that the PEI-FA absorbents synthesized as such not only have outstanding performance in terms of capacity, sorption and desorption rates, regenerability, and low cost but also make the fly ash from an industrial waste into a valuable material. This will prove to be a valuable measure in environmental protection.