SBA immobilized phosphomolybdic acid: Efficient hybrid mesostructured heterogeneous catalysts

SBA-15 and SBA-3 mesoporous silicas are synthesised by P123 and CTAB surfactants via hydrothermal and liquid phase deposition procedures, respectively. An inorganic-organic hybrid mesoporous material is then synthesised by functionalization of SBA-15 with aminopropyl functional groups via grafting method. After characterization, effect of immobilizing support and functional groups on intercalation of phosphomolybdic acid (H3PMo12O40) is taken into consideration. The immobilization pattern is discussed and supported H3PMo12O40 catalysts are characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), EDX, inductively coupled plasma (ICP), FT-IR, and UV-vis analysis. The newly synthesised hybrid catalysts are investigated for epoxidation of cyclooctene in presence of hydrogen peroxide as oxidant. The reaction mechanism is discussed. Furthermore, effects of different immobilizing supports and functionalization on catalyst activity, stability, and reusability are taken into consideration. Similar catalytic reactions are carried out with pristine supports and neat H3PMo12O40 (homogeneous). Results reveal that the mesostructured phosphomolybdic acid based catalysts are shown to be efficient and selective heterogeneous catalysts for oxidation of alkenes. (C) 2009 Elsevier B. V. All rights reserved.