Modifier-enhanced supercritical CO2 extraction of organic template from aluminosilicate MCM-41 materials: Effect of matrix Al/Si ratios and different modifiers

• Aluminum incorporation has rendered the template/matrix interactions stronger.
• SCCO2 extraction efficiencies decrease as the matrix Al/Si molar ratio increases.
• Well-performed methanol has resulted in extraction efficiencies of 60–87%.
• Modifiers and Al/Si ratio both strongly affect the materials structural properties.
• Samples treated by SCCO2/acetic methanol seem to be more catalytically active.

The introduction of polar modifiers usually can make supercritical CO2 extraction more attractive in various potential applications. In this work, modified SCCO2 extraction has been investigated for removing the template cetyltrimethylammonium bromide (CTMABr) from newly synthesized aluminosilicate MCM-41 materials. The effects of the modifier identity and matrix Al/Si ratio on the extraction efficiency and material structural properties are then investigated in detail through numerous characterization methods. The results shows that the incorporation of aluminum into the MCM-41 framework has led to considerable decrease in the extraction efficiencies and the efficiencies are observed to decrease as the Al/Si molar ratio increases arising from the strong interactions between the template and the Al species incorporated into the matrix. Methanol modifier has resulted in much higher extraction efficiencies in the range of 60–87% depending on the Al/Si molar ratio in the sample matrix. Nitrogen adsorption/desorption and XRD results shows that the modifier identity and matrix Al/Si ratio have strongly influenced the structural properties of resultant mesoporous materials. Friedel–Crafts acylation reaction of 2-methoxynaphthalene has been analyzed through gas chromatography and the results show that the sample treated with SCCO2 extraction modified with acetic methanol is more catalytically active than the directly calcined counterpart.

Effects of Si/Al ratio on extraction efficiency obtained in 3 h at 350 bar and 85 °C with respective liquefied CO2 and methanol modifier flow rates of 1.0 and 0.1 ml/min.Figure optionsDownload as PowerPoint slide