High CO2 adsorption on amine-functionalized improved macro-/mesoporous multimodal pore silica

Abstract

In recent years, amine functionalized materials have attracted great interest as prospective solid adsorbents for CO2 capture. However, the amine functionalization of traditional supports (such as SBA-15, etc.) can lead to a decrease in the pore volume and specific surface area of the adsorbent, which significantly affects the CO2 adsorption–desorption kinetics. To overcome this problem, the macro-/mesoporous multimodal pore silica was quickly synthesized using a ternary nonionic surfactant as a template through a partitioned collaborative self-assembly method, and impregnated with TEPA. The prepared support HMS-4 h has bimodal pores (pore size of 9.41 nm and 90 nm), which can not only improve the dispersibility of the loaded TEPA, but also effectively reduce the diffusion resistance of CO2. At the same time, the high surface area (838 m2/g) and large pore volume (2.34 cm3/g) of HMS-4 h can further improve the adhesion and quantity of amine-based active sites. The highest adsorption capacity reaches 6.04 mmol/g for HMS-4 h-75%TEPA at 90 ℃ and 1 bar. The adsorption capacity for HMS-4 h-75%TEPA was steady after 10 adsorption–desorption cycles. BET, XRD, FT-IR, SEM, TG-DTG were used to characterize the performance of the adsorbent. The CO2 adsorption mechanism and the effects of organic amine loading, adsorption temperature and CO2 concentration on CO2 adsorption performance were systematically studied. The research shows that HMS-4 h-75%TEPA is an excellent adsorbent with high adsorption capacity in a wide temperature range, and low energy. This provides a reference for the design of high-performance solid amine CO2 adsorbents in the future.