Amine-functionalized titania-based porous structures for carbon dioxide postcombustion capture

An amine-grafted solid sorbent is a promising alternative to aqueous amine scrubbing for removing CO2 from the flue gas of coal power plants. In this study, phosphonic and carboxylic acids have been investigated as alternative anchor groups to trimethoxysilanes to synthesize amine-functionalized TiO2-based sorbents. Several supports, namely, mesoporous TiO2 beads, TiO2 nanoparticles (Degussa P25), and TiO2/ZrO2 composite beads, and a range of amines (1, 2, and 3 carbon-chain primary amine) have been assessed for CO2 adsorption at 30 C and up to 101 kPa CO2. As a general trend, CO 2 adsorption capacity increased with the carbon-chain length of the amine. Finally, materials functionalized with amino acids, l-glutamine or l-arginine, were investigated; the latter showed the highest CO2 adsorption capacity (0.4 mmol/g at 30 C and 20 kPa CO2) due to the higher pKa (12.10) of one of the amino groups.