Development of adsorbent technologies for post-combustion CO2 capture

Increasing awareness of the influence of greenhouse gases on global climate change has led to recent efforts to develop strategies for the reduction of carbon dioxide (CO2) emissions. The strategy that is receiving the most attention involves the capture of CO2 from large point sources, such as fossil fuel-fired power plants, and long-term storage underground or in the ocean. CO2 capture can be achieved either by post or pre-combustion capture at ambient or high pressure respectively. Aqueous solutions of amines have long been used by industry as absorbents for acid gas (CO2,H2S) removal, but have a large number of short comings. As an alternative, adsorption is one of the more promising technologies for capturing CO2 from flue gases, potentially avoiding the shortcomings of aqueous amine systems. In this paper the development of solid adsorbents for post-combustion capture will be described. The generation and testing of a range of adsorbents for post-combustion capture of CO2 at ambient pressure has demonstrated the need for chemical type adsorbents. A range of chemical type adsorbents have been generated by two methods: Modification of the surface chemistry of both low cost carbons and mesoporous silica by impregnation with a basic nitrogen-containing polymers (i.e., polyethylenimine). Generation of a range of high nitrogen content carbon matrix adsorbents by carbonisation and subsequent thermal or chemical activation of a range of nitrogen compounds.