Structure design of a hyperbranched polyamine adsorbent for CO2 adsorption

An amino-terminated hyperbranched polymer (HBP-NH2) has been prepared through the Michael addition reaction between amines and methyl acrylate (MA) at 0 degrees C, followed by self-condensation of the addition reaction products at 100 degrees C and 140 degrees C. A novel CO2-imprinted hyperbranched polymeric adsorbent (IHBPA) with a high amino density was conveniently prepared by using glutaraldehyde to cross-link HBP-NH2 which had pre-adsorbed CO2. Through comparing the adsorption capacities of the IHBPA with HBPA, which was prepared with a similar procedure to that of IHBPA but without CO2 pre-adsorption, it could be found that the pre-adsorbed CO2 on HBP-NH2 would occupy the reactive sites of amino groups, and play the role of imprinting in the preparation of the adsorbent. The adsorption capacity of the IHBPA could thus be improved. After reducing the imino groups of the IHBPA to alkyl amine by NaBH4, the adsorption capacity of the reducing solid amine adsorbent (IHBPA-R) can be further improved. The prepared solid amine adsorbents also showed promising regeneration performance, which could maintain almost the same adsorption capacity for CO2 after 10 adsorption and desorption recycles. The high CO2 adsorption capacity (7.65 mmol g(-1)) of IHBPA-R can be attributed to its high amino density, terminal amine and hyper-branched structures.