Structure design of a hyperbranched polyamine adsorbent for CO2 adsorption

Abstract

An amino-terminated hyperbranched polymer (HBP-NH₂) has been prepared through the Michael addition reaction between amines and methyl acrylate (MA) at 0 °C, followed by self-condensation of the addition reaction products at 100 °C and 140 °C. A novel CO₂-“imprinted” hyperbranched polymeric adsorbent (IHBPA) with a high amino density was conveniently prepared by using glutaraldehyde to crosslink 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.