Preparation and structure tuning of CO2 adsorbent based on in-situ amine-functionalized hierarchical porous polymer

Abstract

Amine-functionalized porous adsorbent is one kind of important materials in carbon dioxide capture due to its stability and efficiency. In this study, a copolymer (polyHIPE) with interconnected macropore networks, hierarchical porous structure and abundant branched amino groups was prepared by high internal phase emulsion (HIPE) strategy via copolymerization of styrene (St), divinylbenzene (DVB), tetraethyl orthosilicate (TEOS), and triethoxyvinylsilane (VTEO), and then a novel amine-functionalized CO 2 adsorbent was synthesized by in situ ring-opening grafting copolymerization of aziridine with the polyHIPE. The structure, morphology, and physicochemical properties of the polyHIPEs were characterized by FTIR, TEM, TGA, and SEM. The key roles of VTEO and TEOS in introducing active hydroxyl groups onto the surface of the inert polymer was evaluated, which was essential to improve the hydrophilicity of the polyHIPE and to provide reactive sites to combine with amine agents. The contact angle of the polyHIPE while copolymerized with TEOS and VTEO significantly was decreased from 144° to 72°. In order to further increase the specific surface area of the polyHIPEs, post crosslinking of polyHIPEs was implemented through a Friedel–Crafts reaction. The specific surface area of post-crosslinked polyHIPE could reach 513 m 2 /g, which was proven to be effective to enhance its CO 2 adsorption capacity. Finally, the abundant branched amino sites via aziridine grafting and high surface area greatly enhanced CO 2 adsorption capacity of the amino-modified polyHIPEs. The adsorption capacity of 2.40 and 3.25 mmol CO 2 /g could be achieved under dry and humid conditions in 0.1 atm partial pressure of CO 2 , respectively. • The hydroxyl groups modified monolithic was synthesized by one-step high inner phase emulsion copolymerization. • The post-crosslinking and in-situ grafting of amino obtained higher specific surface area and more CO 2 adsorption sites. • The polyHIPE-V 1 T 2 -HCP-NH monolithic exhibits obviously high CO 2 adsorption capacity and amino efficiency. • 3.25 mmol CO 2 /g-adsorbent and amine efficiency of 0.65 mmol CO 2 /mmol N could be achieved under humid conditions.