Supercritical Fluid Extraction of a Nonionic Surfactant Template from SBA-15 Materials and Consequences on the Porous Structure

Abstract

SBA-15 mesoporous materials were synthesized using the method reported by Zhao et al. Surfactant was removed from as-made materials by means of different techniques: thermal treatment under air atmosphere, solvent washing at different temperatures, and supercritical CO2 extraction in the presence and absence of cosolvents. The structure of resulting materials was characterized using conventional techniques: nitrogen and argon adsorption measurements, powder X-ray diffraction (XRD), thermogravimetric analysis (TGA), infrared spectroscopy (FT-IR), and 29 Si MAS NMR. The efficiency of surfactant removal using CO2 under supercritical conditions is similar to that obtained by means of solvent washing under reflux but shows some improvements in the presence of cosolvents. Mesoscopic properties of mildtemperature solvent extracted SBA-15 materials depend on the efficiency of the surfactant removal and the use of supercritical CO 2 as solvent. Likewise, the size and volume of the complementary microporosity detected in the treated materials is closely related to the strategy of removal of hydrophilic poly(ethyleneoxide) chains of the triblock copolymer template occluded within the siliceous walls of the SBA-15 mesophase during the synthesis.

Production of Renewable Hydrogen from Glycerol Steam Reforming over Bimetallic Ni-(Cu,Co,Cr) Catalysts Supported on SBA-15 Silica

“…In this context, alcohols derived from biomass, like methanol [4], ethanol [3,5], or glycerol [6][7][8] may also be reformed to generate hydrogen, turning reforming into a zero net carbon emissions process. and tailored particle morphology [31]. Large surface area and mesoporous structure of the support have been demonstrated to play an important role in improving Ni dispersion and in suppressing Ni sintering [19,32].…”

Pore Expansion in Mesoporous Silicas Using Supercritical Carbon Dioxide

“…Several researchers [23][24][25] have recently exploited sc-CO 2 in the post synthesis treatment of mesoporous silica. They reported that modified CO 2 could be used to extract the surfactant template from the uncalcined mesoporous silica thus facilitating in the recycling of the surfactant.…”

Bifunctional Fe-SBA-15-SO3H Mesoporous Catalysts with Different Si/Fe Molar Ratios: Synthesis, Characterization and Catalytic Activity

“…A slight hysteresis loop and sharp adsorption step at relative pressures around 0.4-0.6 identify the characteristics of this isotherm 38,39 and the sharpness of the adsorption branches indicates narrow pore size distribution. 40 In Figure 2(a), the slope of the isotherm after the low-pressure adsorption step is lower for Fe loaded SBA-15-SO 3 H than that of pure SBA-15-SO 3 H, corresponding to a lower area of the mesopore surface.…”