Abstract
Ce-modified mesoporous silica materials MCM-41 and SBA-15, namely 32 wt % Ce–Si–MCM-41, 16 wt % Ce–H–MCM-41 and 20 wt % Ce–Si–SBA-15, were prepared, characterized and studied in the selective preparation of trans-carveol by α-pinene oxide isomerization. The characterizations of these catalysts were performed using scanning electron microscopy, X-ray photoelectron spectroscopy, nitrogen adsorption and FTIR pyridine adsorption. Selective preparation of trans-carveol was carried out in the liquid phase in a batch reactor. The activity and the selectivity of catalyst were observed to be influenced by their acidity, basicity and morphology of the mesoporous materials. The formation of trans-carveol is moreover strongly influenced by the basicity of the used solvent and in order to achieve high yields of this desired alcohol it is necessary to use polar basic solvent.
Highlights
Isomerization reactions of the terpene oxides have become a very interesting topic in the recent years [1,2]
Several ceria supported on mesoporous materials MCM-41 and SBA-15 catalysts were prepared in the current research, namely 32 wt % Ce–Si–MCM-41, 16 wt % Ce–H–MCM-41 and 20 wt %
The morphology of the Ce–Si–MCM-41 and Ce–H–MCM-41 catalysts was studied by scanning electron microscopy (Figures 2 and 3)
Summary
Isomerization reactions of the terpene oxides have become a very interesting topic in the recent years [1,2]. The high selectivity, 73% to trans-carveol at 98% conversion, was achieved using cerium and tin supported catalysts and a polar basic solvent: dimethylacetamide [5]. The main focus of this research was on testing ceria supported by various ordered mesoporous silica materials for selective preparation of trans-carveol. Activity and selectivity of these catalysts were correlated with their physico-chemical properties; mainly with their acidity, structure of mesoporous materials and loaded amount of ceria. Several ceria supported on mesoporous materials MCM-41 and SBA-15 catalysts were prepared in the current research, namely 32 wt % Ce–Si–MCM-41, 16 wt % Ce–H–MCM-41 and 20 wt %. Ce–MCM-41 exhibited high catalytic activity and good selectivity in the liquid phase oxidation of cyclohexane using aqueous hydrogen peroxide as an oxidant and acetic acid as a solvent [13]. Ce–silica mesoporous SBA-15-type material were applied for the cyclohexanol and cyclohexene oxidation with hydrogen peroxide [16]
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