Organic-functionalized molecular sieves. III. Shape selective catalysis

Several organic-functionalized molecular sieves (OFMSs) are investigated fo r use as shape-selective catalysts. OFMSs with the *BEA topology containing ethylcyclohexenyl, phenethyl and mercaptopropyl functional groups are synt hesized and characterized by X-ray diffraction, FT-Raman spectroscopy, soli d-state C-13 NMR spectroscopy, thermogravimetric analysis, nitrogen physiso rption, scanning electron microscopy, energy dispersive spectroscopy, field emission scanning electron microscopy, and transmission electron microscop y. Acidic OFMSs derived from phenethyl and mercaptopropyl containing OFMSs are used in catalytic tests. Sulfonated phenethyl-containing OFMSs can exhi bit poor shape selectivity in discriminating between cyclohexanone and 1-py renecarboxaldehyde reactions with ethylene glycol at low temperatures in th e liquid phase. This poor selectivity is shown to be due to the introductio n of silanol-bound sulfonic acid species on the external surface by sulfona tion of extracted phenethyl-functionalized beta samples. Sulfonic acid cont aining OFMSs derived from the oxidation of mercaptopropyl groups are very s elective for the conversion of cyclohexanone relative to 1-pyrenecarboxalde hyde, with an initial rate ratio (R-HEX/R-PYC) that can exceed 200. The rat e of reaction over this shape-selective catalyst is significantly slower th an over commercial zeolite beta, organic-functionalized mesoporous material s, and homogeneous acids. (C) 2001 Elsevier Science B.V. All rights reserve d.