Removal of CO from pre-combustion CO₂ rich streams using chemical looping technology

• CO 2 purity is crucial for CCS and CCU application. • CO can effectively be removed from CO 2 rich streams by chemical looping. • Based on thermodynamic study Iron and Copper based oxides are the most promising OC. • Exothermic steps in chemical looping offer great opportunities for heat recovery. • Fe 2 O 3 impregnated on Al 2 O 3 showed great performance over multiple cycles at T > 400 °C. Complying with CO 2 purity specifications is unavoidable for any carbon capture technology due to technical, economic, and safety requirements for transportation, storage, and utilization. The tolerated impurity levels can be stringent, leading to a significant increase in capture costs. Depending on the applied technology and the flue gas source, different impurities are present. This study focuses on pre-combustion capture CO 2 purification, in particular removing CO using chemical looping technology. Compared to existing CO removal methods, chemical looping can remove CO with reduced energy penalty while at the same time improve the CO 2 recovery and remove other impurities like H 2 and CH 4 which might be present in pre-combustion CO 2 captured stream. The feasibility of applying chemical looping for deep CO removal (<100 ppm) was first evaluated thermodynamically, considering various oxygen carriers like Ni, Cu, Mn, and Fe. Promising redox couples identified include Cu 2 O/Cu and Fe 2 O 3 /Fe 3 O 4 , while nickel and manganese based oxides showed less potential. Both reduction and regeneration are exothermic, offering opportunities for heat recovery. Iron-based oxygen carriers were further evaluated experimentally, showing excellent performance and stability over ∼200 cycles at 400–550 °C for a 20wt%Fe 2 O 3 impregnated on Al 2 O 3 sample. Higher temperatures showed increased conversion up until 450 °C. Optimal operating temperatures should consider process design and economics, including heat integration options. CO 2 purification by chemical looping appears to be an attractive CO removal technology.