3D Hexagonal Mesoporous Silica and Its Organic Functionalization for High CO₂ Uptake

Abstract

Highly ordered 3D-hexagonal mesoporous silica HMS-3 and its vinyl- and 3-chloropropyl-functionalized analogues HMS-4 and -5, respectively, are synthesized under strongly alkaline conditions at 277 K. Tetraethyl orthosilicate, vinyltrimethoxysilane, and 3-chloropropyltrimethoxysilane are used as silica sources, and cetyltrimethylammonium bromide as the structure-directing agent. The 3D-hexagonal pore structures of HMS-3, 4-, and -5 were confirmed by powder XRD and high-resolution TEM studies. Brunauer-Emmett-Teller surface areas of these materials are 1353, 1211, and 603 m(2) g(-1) for HMS-3, -4, and -5, respectively. Among these materials, vinyl-functionalized mesoporous material HMS-4 adsorbs the highest CO(2) (5.5 mmol g(-1) , 24.3 wt%) under 3 bar pressure at 273 K. The 3D-hexagonal pore openings, very high surface area, and cagelike mesopores as well as organic functionalization could be responsible for very high CO(2) uptakes of these materials compared to other related mesoporous silica-based materials.

A first principles study of CO2 adsorption on α-SiO2(001) surfaces

“…Experimental studies speculate that the cage-like pores of 3D-hexagonal mesoporous silica may partially account for its higher CO 2 uptake than other mesoporous materials having cylindrical pores. 21 The corresponding analytical investigations indicate that the van der Waals (vdW) interaction plays an important role when CO 2 molecules interact with silica. 22,23 During the last few years, a number of studies have been focused on the first principles analysis of a-SiO 2 systems.…”

Synthesis of VTMS(X)-HMS-3 mesoporous ordered silica for hydrogen storage

“…Samples were synthesized following a protocol adapted from Nandi et al [5] and Dutta et al [29] Deionized water (24 mL, 1.332 mol), ethanol (12.7 mL, 217.1 mmol), NH 4 OH (28 wt%) (2.38 mL, 35.22 mmol), and CTAB (0.52 mg, 1.43 mmol) were dissolved and stirred for 30 min at 4 C. TEOS and VTMS, in the appropriate ratio (Table 1), were subsequently added dropwise. The solution was allowed to stir for 3 h at 4 C and then aged statically for an additional 16 hh at the same temperature.…”

Surface Heterogeneity Affects Adsorption Selectivity for CO2 Over CH4 in Bare Mesostructured Silica with 2D Hexagonal Symmetry and Different Pore Size

“…The growing attention and interest for further development is due to the large surface area (up to 2000 m 2 g −1 ) and the highly uniform pore size, beside the many approaches available to functionalize their surface for specific applications. [1][2][3][4][5][6][7][8][9][10][11][12] DOI: 10.1002/admi.202300196 Among the mesostructured silica, MCM-41 and SBA-15 are the most widely investigated and employed ones, because of their regular 2D hexagonal array (P6mm space group symmetry) of highly uniform parallel mesopores, with a pore diameter of 2-10 and 5-30 nm, respectively. [1] SBA-15 also has a network of micropores (diameter <2 nm) interconnecting the mesopores.…”