Manganese-containing hollow TS-1: Description of the catalytic sites and surface properties for solvent -free oxidation of ethylbenzene

Hollow MnOx/TS-1 catalyst was prepared by dissolution-recrystallization and impregnation method, and its catalytic activity was evaluated in aerobic oxidation of ethylbenzene under solvent-free conditions. Tetrahedral TO4+ and MnOx species homogeneous dispersed on the hollow TS-1 surface and strong favourable synergic interactions between them occurred, which supported by the Comprehensive analysis of XRD, N-2 physical adsorption, TEM, FTIR, UV-vis, XPS and Raman spectroscopy. The virtue of such synergic effect was reflected in a catalytic efficiency enhancement of valuable ketone and alcohol products (TOF = 137 h(-1)): MnOx/TS-1 catalyst showed about 2.2 times higher activity compared to MnOx/Silicalite-1 references. Furthermore, the Mn species content and calcination temperature of the Mn0x/TS-1 catalyst presented significant effects of lower-nuclearity Mn species on the structural, chemical, and catalytic properties. Based on the theoretical calculations, the reaction mechanism was proposed where the cleavage of the longer methylene C-H bond (1.0935 A) of ethylbenzene and O-O bond (1.5267 A) of alkyl hydroperoxide over the O-Ti-O Mn sites is a key step to yield radical continuously for recycle. (C) 2016 Elsevier B.V. All rights reserved.