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Supported amines have been shown to absorb CO2 cyclically under temperature swing absorption (TSA) conditions, and show a substantial decrease in desorption energy compared to zeolite materials. Supported amines may therefore be a viable alternative for cyclic capture of CO2 on long-term space missions where minimal energy expenditure is a critical consideration. The research described in this paper presents efforts to improve the TSA-supported amine system with a focus on relationships between important parameters affecting cyclic CO2 capacities, as well as reaction effects of CO2 with the modified amine tetraethylenepentamine.

In this study, a parametric examination of the main factors affecting cyclic CO2 absorption into supported amine sorbents has been conducted. A bench-scale test apparatus and Taguchi statistical design of experiments were used to assess the importance of cycle time, inlet CO2 concentration, residence time, humidity, absorption temperature, desorption temperature and desorption pressure on cyclic CO2 capacity. Two amine sorbents were considered: TEPAN and modified E-100. Amine decomposition, amine oxidation, and the effects of amine chemical composition were also examined. For typical ranges of system variables found on-board the space shuttle orbiter, results indicated that desorption pressure over the range of 25–85 torr, desorption temperature over the range of 50–60°C, absorption temperature over the range of 20–30°C, and CO2 concentration over the range of 6–9 mmHg were the most important variables affecting cyclic CO2 removal capacity.