Co-grafting of polyethyleneimine on mesocellular silica foam for highly efficient CO2 capture

Abstract

Solid amine materials have emerged as a class of adsorbent with promising potential for CO2 capture from gas mixtures, such as biogas and flue gas. In this work, we developed a novel CO2 capture material via co-grafting of polyethyleneimine (PEI) on mesocellular silica foam (MCF), and (3-glycidyloxypropyl)triethoxysilane (GPTES) was first used as a bridging medium. In the fabrication procedure of MCF@G-35.6 %PEI, a simple impregration of PEI in MCF modified with epoxy groups was conducted. In this procedure, the co-grafting of PEI was realized in terms of a portion of PEI (21.3 wt%) was anchored on the pore surface of MCF via the epoxy/amine reaction and the rest of PEI (14.3 wt%) could be stably attached to the pore surface of MCF via its interaction with anchored PEI. After systematic evaluation, the MCF@G-35.6 %PEI exhibited a maximum CO2 adsorption capacity of 2.78 mmol/g at 50 °C and 50 %RH and fast adsorption kinetics with equilibrium time (break through from C/C0 = 5 % to 95 %) is 22.85 min. Meanwhile, outstanding CO2 adsorption capabilities within a wide temperature range of 30–90 °C and a large concentration range of 5–30 % vol. CO2 were obtained by the use of MCF@G-35.6 %PEI. More importantly, the MCF@G-35.6 %PEI also exhibited an excellent long-term stability over 50 consecutive cycles. CO2 adsorption kinetics of the sorbent was found to follow Avrami’s fractional order model and intraparticle diffusion model. Furthermore, temperature-programmed desorption was conducted to investigate the desorption kneitics and adsorption mechanism. All these findings demonstrate the great potential of MCF@G-35.6 %PEI for carbon capture and sequestration (CCS) technology.