Industrially Compatible Synthesis of Mcm-41 with Spatial Organization at the Macro- Mesoscale

Abstract

Nowadays industrial requirements point to high-performance processes but cost-effective materials to maximize their benefit/cost balance. This paper describes the properties of a macro- mesoporous MCM-41 silica with very high surface area obtained from inexpensive reagents —industrial sodium silicate as a source of silicon and industrial CTAC as template— with potential use in an environmental application such as CO2 capture. The material exhibited an aperiodic 3D spatial organization at the macro- mesoscale formed by connecting well-ordered MCM-41. This organization can be rationalized in terms of the nature and interaction of the reactants. Thus, the conjunction of poly (N-silicate) and features in CTAC, such as the weakly bonding counterion (Cl-), ethanol and unreacted amine, gave rise to different morphologies and variable channel lengths, porosity at different length scales producing meso/macro arrangements, and a spongy structure as a disordered minority phase. The hierarchical organization improved the chances for obtaining a more uniform APTS loading enhancing CO2 retention. Then the use of industrial reactants offers two important advantages: (i) the appearance of macro- mesocavities, which in turn opens up the possibility of using the material in applications that require a porosity greater than that intrinsic to MCM-41; (ii) the production cost is reduced by 80% in comparison to a traditional synthesis using alkoxysilanes and CTAB, and is negligible when compared to the synthesis involving analytical grade CTAC.

Keywords: MCM-41, inexpensive industrial surfactant, industrial sodium silicate, macro- mesostructure, CO2 adsorption