A regenerable adsorbent suitable for carbon-dioxide enrichment at 180°C

With the continuous development of carbon neutralization, CO2 capture from flue gas has become a hot topic. This work modifies HSSZ-13 by Mg and organic amines, and applies the adsorbent in CO2 capture. As a result, co- doping of TEPA and Mg with a ratio of 1:2 results in the best performance, and obtains an adsorption capacity of 2.03 mmol center dot g-1 at 110 degrees C. This capacity is bigger than those with no modification (0.19 mmol center dot g-1), only Mg doping (1.21 mmol center dot g-1) and only TEPA doping (1.81 mmol center dot g-1). The best adsorbent is stable in the cyclic adsorption with no decrease in CO2-enrichment efficiency for nine times. When the temperature is increased to 180 degrees C, the adsorbent still reaches one-third of the highest capacity. The adsorbent maintains 46 % of the capacity even under 10 % of vapor at 110 degrees C. Mechanism investigation shows that TEPA and Mg2+ have a synergistic effect on CO2. In brief, TEPA bonds with CO2 to form C-N. Mg2+ induces a one-dimensional chain of ammonium carbamate parallel to the Mg2+ chain. The resulted spatial structure further adsorbs CO2. Therefore, above results provide an effective adsorbent for CO2 capture from real flue gas at 110-180 degrees C and under co-existing vapor.