HIGH TEMPERATURE ABSORBENTS FOR CO_2 CAPTURE

摘要

A screening of natural minerals for CO_2 absorption properties revealed that some carbonates of the dolomite group are interesting high temperature sorbents for CO_2 recovery. The chemical/cycling stability is dependent on their chemical composition, an increased concentration of inert components influences positively the cycling stability of the sorbent materials. Natural complex silicates containing calcium carbonate showed in general poor CO_2 sorbent qualities, but cycling and mechanical stability can be considered very good. Some of them, e.g. spurrite, showed high CO_2 absorption capacity and good attrition stability. The presence of steam in the gas atmosphere increases the absorption reaction rate, but reduces the sorbent lifetime by enhancing the sintering of pores. The coating of natural sorbent grains with SiO_2 or Al_2O_3 improves the mechanical stability, however, it impedes the CO_2 absorption properties. Crushing and milling can influence the absorption behaviour of the sorbents due to the change of their chemical composition.