Guanidinylated poly(allylamine) supported on mesoporous silica for CO2 capture from flue gas

• Silica sorbents impregnated with PAA and Guanidinylated PAA (GPAA) for CO2 capture.
• The CO2 uptake of PAA and GPAA sorbents are comparable at low temperatures.
• GPAA sorbents demonstrated better CO2 capture performance at elevated temperatures.
• GPAA sorbents more stable during cyclic CO2 adsorption at high temperatures.

The CO2 adsorption performance of aminosilica adsorbents prepared by the impregnation of poly(allylamine) (PAA) and guanidinylated poly(allylamine) (GPAA) into silica mesocellular foam supports is evaluated. The effect of amine loading on the CO2 capacity is consistent with previous reports of poly(allylamine) impregnated adsorbents, whereby the capacity increases initially with increasing amine loading and then drops at very high amine loadings, due to restricted access to the amine sites at high loadings. The CO2 capacity of the new GPAA impregnated adsorbents decreases with an increase in adsorption temperature, showing comparable capacities to those for PAA impregnated adsorbents at low to moderate temperatures. However, at adsorption temperature higher than 75 °C, the CO2 capacities of GPAA adsorbents are higher than those for PAA adsorbents, ∼70% higher at the highest temperature studied, 140 °C. CO2 adsorption–desorption cycling experiments show that the GPAA adsorbents have a better stability and regenerability at higher temperatures, making this class of materials suited for temperature swing cycles operating in a higher temperature regime than traditional aminosilica adsorbents based on PEI.