Study of Amine Impregnated on Silica Support for CO2 Capture

by Tanthana, Jak

The rapid increase in CO2 emission in recent years has become a major concern because of its potential link to global climate change. Among CO2 contributors, coal-fire power plant accounts for more than 30% of total CO2 emission worldwideThree major approaches for capture of CO2 are proposed: postcombustion, oxyfuel and precombustion. Each has distinct advantages and disadvantages. Postcombustion utilizing amine based absorption process by far is the most fundamentally established and can be retrofitted to existing coal-fire power plants around the globe. Limited by high heat of reaction, the amine absorption process requires a significant amount of energy during solvent regeneration. Large physical facility foot print and corrosive problems are among the important issues which need to be addressed. Utilizing sorbent impregnated with amine specie shows competitive CO2 capture ability and may lead to a more practical solution from its lower operating temperature in the regeneration step, smaller foot print and less corrosion. Many solid sorbent products available commercially can be tailored to meet certain specifications such as controlled pore size distribution, high porosity or govern specific reactions at relatively low cost. Silica fume was chosen in this study due to its high availability, high surface area and flexibility to modify surface properties using various methods of treatments. In this study, silica support sorbent was impregnated with tetraethylenepentamine by various wt% concentrations applying an ex-situ impregnation method. Acid and Base v treatment of amine impregnated samples were employed in the study. The sorbents were then characterized as to their performance of CO2 absorption-desorption. The capturing performance and effect from acid/ base were evaluated. Results of this study concluded that ex-situ impregnation can be used to successfully prepared tetraethylenepentamine impregnated SiO2. The sorbents exhibited ability to perform CO2 absorption-desorption exceeding primary target capture performance set by Department of Energy (DoE) under optimized concentration of tetraethylenepentamine. Intensity of IR absorbance may correlate with the concentration of amine functional groups on surface of SiO2. Weakly and strongly bonded CO2 with tetraethylenepentamine were suggested. Hypothesized form of absorbed species of monodentate bicarbonate and bidentate bicarbonate were detected in the study. Acid treatment causes performance degradation which was evident from the degradation of the amine functional groups on the silica surfaces while base treatment did not improve nor degrade the sorbent performance. Hence, CO2 absorption-desorption mechanism is not altered by the base treatment.