Captured carbon dioxide (CO₂) streams contain impurities that must be removed to meet specifications for safe transport, storage, and utilisation. Among these impurities, oxygen poses challenges due to its high reactivity and potential to cause corrosion, motivating stringent purity limits below 10 ppmv.

Building on recent experimental demonstrations of catalytic oxygen removal using hydrogen (H₂), carbon monoxide (CO), methanol (CH₃OH), and methane (CH₄) as reducing agents, a new study performed at the Georgia Institute of Technology, presents a technoeconomic (TEA) and life cycle assessment (LCA) of these four catalytic purification pathways.

Process flowsheets were developed and simulated in Aspen Plus for CO₂ streams representative of both low-temperature and high-temperature capture processes, with integrated heat recovery and energy optimisation.

Results showed that total purification costs were dominated by feedstock procurement and electricity consumption. Among the studied reducing agents, the CH₄-assisted route achieved the lowest purification cost and highest CO₂ recovery. Sensitivity analyses showed that the H₂ route became competitive at H₂ prices below $0.56/kg to $0.84/kg, depending on the CO₂ feed temperature conditions.

Environmental impacts were primarily driven by indirect CO₂ emissions from raw material production and utility consumption.