| Abstrakt: |
The rapid cleanup of endogenous C02 has become a necessity in environmental control and life support systems (ECLSSs), to ensure crew safety and long-term task execution. The extensively used non-regenerable LiOH and soda time adsorbents, although exhibit high CO2 storage capacities and fast kinetics, can hardly fulfill the demands of reduced launch weight and storage volume in the space- and load-limited ECLSSs. New C02 adsorbents with desirable attributes including high C02 uptakes, good selectivity, facile regeneration, fast adsorption and desorption kinetics, and good multicycle stability are urgently needed. We developed amine-functionalized adsorbents by loading tetraethylenepentamine (TEPA) on mesoporous supports of activated carbon (AC), aluminum oxide (AO) and silica gel (SG). The adsorbents were characterized by N2 adsorption-desorption, thermogravimetric analysis (TGA), Foul-ier transform infrared spectroscopy (FT-[R), and scanning electron microscope (SEM) to study their microstructural properties. 02 adsorption capacities and kinetic performance of tlie adsorbents with different supports and various amine loadings (10-50 wt%) were evaluated in 2%(02 at 20 °C. The effects of support and amine loading on the structure-performance relationships of the adsorbents were demonstrated. The TEPA-SG-20 adsorbent 20 wt% TEPA loaded on silica gel support) exhibits the highest CO2 adsorption capacity of 1.90 mmol (02/and the maximum amine efficiency of 0.48 nimol COWmmol N. TEPA-SG-20 also exhibits fast CO2 adsorption kinetics, and the Avrami fractional order kinetic model provides a satisfactory correlation of the experimental CO2 uptakes. Furthermore, the TEPA-SG-20 adsorbent can be efficiently regenerated at 110 with a great regeneration efficacy of 97%. The desired adsorbent also exhibits good working stability with low loss-in-capacity of 4.32% in 10 consecutive cycles. The good C02 adsorption performance of TEPA-SG-20 is associated with the excellent microstructural properties such as high surface area, great pot·e volume and uniform dispersion of amine species. Overall, the desired TEPA-SG-20 adsorbent shows promise for lowconcentration C02 removal in ECLSSs. [ABSTRACT FROM AUTHOR] |
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