Cost-effective synthesis of hierarchical MCM-41 silica for enhanced CO2 adsorption

Abstract

The use of porous materials as CO2 adsorbents in carbon capture and storage technologies is a promising alternative for mitigating emissions of this greenhouse gas. Among them, MCM-41 type silicas are particularly interesting due to their high specific surface area and their potential to be modified according to the application of interest. One of their main disadvantages is the cost of conventional reactants used in their synthesis. This work studied the production of a mesoporous MCM-41 type silica obtained from very low-cost commercial industrial-grade solutions, modified with amino groups for its application as CO2 adsorbent. The synthesized material was characterized using SAXS, SEM, HRTEM, and N2 adsorption/desorption at 77 K. Porosity at different meso-macro scales was observed (4-1000 nm), in addition to the intrinsic hexagonal mesostructure of MCM-41, characterized by a high specific surface area (SBET = 1134 m²/g) and a high volume of meso- and macropores (VP meso = 1.01 cm³/g and VP macro = 4.70 cm³/g). Furthermore, different morphologies and channels with variable lengths and curvatures were observed. The material functionalized with APTS showed slightly higher adsorption capacity results than those found in the literature, reaching 1.28 mmol/g at 25 °C and 760 mmHg.