Polyethylenimine-impregnated resins: The effect of support structures on selective adsorption for CO2 from simulated biogas

Abstract

Adsorbents prepared by impregnating porous materials with polyethylenimine (PEI) are potential candidates for CO2 capture from biogas. The objective of current research is to investigate the effect of structures of resins on CO2 capture performance of PEI-impregnated resins from simulated biogas. Here, three commercially available resins (D101, X-5 and ADS-17) with different pore volumes or surface functional group were selected as supports. N2 adsorption-desorption, infrared spectroscopy, scanning electron microscopy and thermal gravimetric analysis were used to characterize the resins before and after impregnating PEI. Breakthrough experiments revealed that all these PEI-impregnated resins could selectively adsorb CO2 at ambient temperature. Meanwhile, PEI-impregnated ADS-17 exhibited a superior performance among the tested adsorbents, despite that it had the lowest BET surface area and total pore volume. It is mainly because that ADS-17 had uniform voids and carbonyl group, enhanced the dispersion of PEI and thus improved the CO2 adsorption performance. In addition, ADS-17-20% PEI possessed excellent regenerability. The influence of gas flow rate and temperature on the CO2 adsorption behavior upon ADS-17-20% PEI was also investigated. It was found that the adsorption capacity did not depend much on the flow rate when the gas flow rate ranging from 100 to 200 mL/min. When the temperature was increased from 25 to 45 °C, a slight increase in CO2 adsorption was observed. Furthermore, CO2 adsorption performance of ADS-17-20% PEI can be improved under humid condition.