Engineering of Silica Mesoporous Materials for CO 2 Adsorption.

Adsorption methods for CO 2 capture are characterized by high selectivity and low energy consumption. Therefore, the engineering of solid supports for efficient CO 2 adsorption attracts research attention. Modification of mesoporous silica materials with tailor-made organic molecules can greatly improve silica's performance in CO 2 capture and separation. In that context, a new derivative of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, possessing an electron-rich condensed aromatic structure and also known for its anti-oxidative properties, was synthesized and applied as a modifying agent of 2D SBA-15, 3D SBA-16, and KIT-6 silicates. The physicochemical properties of the initial and modified materials were studied using nitrogen physisorption and temperature-gravimetric analysis. The adsorption capacity of CO 2 was measured in a dynamic CO 2 adsorption regime. The three modified materials displayed a higher capacity for CO 2 adsorption than the initial ones. Among the studied sorbents, the modified mesoporous SBA-15 silica showed the highest adsorption capacity for CO 2 (3.9 mmol/g). In the presence of 1 vol.% water vapor, the adsorption capacities of the modified materials were enhanced. Total CO 2 desorption from the modified materials was achieved at 80 °C. The obtained silica materials displayed stable performance in five CO 2 adsorption/desorption cycles. The experimental data can be appropriately described by the Yoon-Nelson kinetic model.