Alkylation of isobutane/1-butene on methyl-modified Nafion/SBA-15 materials

Hydrophobicity modification of the intrinsic polarity of the surface of SBA-15 mesoporous by ethoxytrimethylsilane was used in this work to make hybrid organic–inorganic mesoporous matrix. This matrix was functionalized with perfluorosulfonic acidic Nafion resin by a post-synthetic impregnation method. Characterized by N2-physisorption, XRD, and transmission electron micrographs (TEM), all the materials synthesized were highly ordered. Elemental analysis, 29Si MAS NMR, thermal gravimetric analysis (TGA), energy-dispersive X-ray (EDX) and potentiometric titration showed that trimethylsilane is grafted on the surface by capping the OHs and the Nafion resin was incorporated, revealing a strong solid acid with hydrophobic surface. The alkylation of isobutane/1-butene was thereafter evaluated on each material under specified conditions. Compared with the polar surface of conventional SBA-15 and commercial Nafion silica nanocomposite SAC-13, methyl-modified surface of SBA-15 material (denoted as Me-SBA-15) is a much better solid acid catalyst for isobutane/1-butene alkylation.

Graphical abstractMesostructured SBA-15 was modified by OH capping and functionalized with Nafion resin. The resulting mesostructured materials (Nafion/Me-SBA-15) with strong acid sites and hydrophobic surface exhibited excellent activity and efficiency in the production of isooctane compared with Nafion/SBA-15 and commercial Nafion silica SAC-13. Capping of surface OH diminishes the surface silanol density and provides a hydrophobic environment for the isobutane/1-butene reaction.Figure optionsDownload full-size imageDownload high-quality image (101 K)Download as PowerPoint slide