High temperature recovery of CO2 from flue cases using hydrotalcite adsorbent

Experimental and theoretical studies on the high temperature recovery of CO P from flue gases are presented. The work employs a potassium promoted hydr otalcite adsorbent, for which CO2 capacities in excess 0.8 mol kg(-1) were measured at temperatures of 481 K and 575 K and in the presence of high con centrations (similar to 30% (v/v)) of water. Elution profiles from a bench- scale adsorption unit also enabled analysis of adsorption and desorption ki netics. A cyclic and multibed process for the continuous and energy efficie nt recovery of CO2 is proposed. The process involves an integrated energy r ecovery step for the generation of steam, which is then used for the recove ry of CO2 from the adsorbed phase. A mathematical model for the CO2-hydrota lcite system, based on measured equilibria and kinetic data, is used for th e preliminary assessment of the process, e.g. in terms of CO2 product purit y and steam consumption. Particular attention is given to CO2 recovery from the stack gas of a typical 10 MW coal-fired power plant. The work has appl ication to existing industrial processes in which recovered CO2 (at elevate d temperatures) can be used as a feedstock for further catalytic processing , such as dry methane reforming and carbon gasification.