Synthesizing and Characterizing a Mesoporous Silica Adsorbent for Post-Combustion CO2 Capture in a Fixed-Bed System

Abstract

MCM-41, a mesoporous silica with a high surface area and hexagonal structure, was synthesized, and commercial nano-silicon dioxide (SiO2) was used as a solid adsorbed in post-combustion CO2 capture. The CO2 adsorption experiments were conducted in a fixed-bed adsorption system using 5–15 vol.% CO2/N2 at a flow rate of 100 mL/min at varying temperatures (20–80 °C) and atmospheric pressure. Analyses (X-ray diffraction, nitrogen adsorption-desorption isotherms, Fourier-transform infrared spectroscopy, and transmission electron microscopy (TEM)) revealed that the synthesized MCM-41 has mesoporous characteristics: a high surface area and large pore volumes. The CO2 adsorption capacity of MCM-41 and commercial nano-SiO2 increased considerably with increasing CO2 concentration and temperature, peaking at 60 °C. Below 60 °C, dynamics rather than thermodynamics governed the adsorption. Increasing the temperature from 60 to 80 °C decreased the adsorption capacity, and the reaction became thermodynamically dominant. Additionally, compared with commercial nano-SiO2, the MCM-41 sorbent demonstrated superior regenerability and thermal stability.