Μελέτη της εναπόθεσης Cr(VI) σε TiO2 και της καταλυτικής συμπεριφοράς των TiO2, Cr/TiO2 καθώς και ζεολιθικών καταλυτών κατά την μερική οξείδωση του λεμονενίου προ π-κυμένιο

Abstract

The main goal of the first part of this work is the investigation of the mode of interfacial deposition and the elucidation of the local structure of chromium-oxo species formed upon impregnation at the “titania / electrolytic solution” interface. To achieve this target we used jointly several methodologies which were combined with spectroscopic techniques as well as with ab-initio calculations for the determination of the kinds of the surface oxygens, their charges and their concentrations. Second Part The main goal of this work is the study of the catalytic production of p-cymene via the dehydrogenation / isomerization of a mixture of monoterpenes and of limonene. The production of p-cymene is of great industrial interest because it can be used in the perfume industry and in the production of synthetic fibers and p-cresol. To achieve this target we developed a experimental setup which included a batch reactor where we studied the reaction in low temperatures. A GC-MS was used for the analysis of the samples taken during the reaction. We have prepared catalytic samples by applying the method of ion exchange. During this method Na+ ions of the zeolite framework were partially exchanged with methyl viologen (MV2+) organic cation. More precisely, two catalytic samples with different amount of MV2+ (NaY/MVI and NaY/MVII) were prepared and characterised using diffuse reflectance spectroscopy. The exact loading of the MV2+ in the prepared samples (NaY/MVI and NaY/MVII) was determined using spectroscopic techniques and carbon analysis. The catalytic production of p-cymene, via the dehydrogenation / isomerization of a mixture of monoterpenes and limonene, took place in the batch reactor in a temperature of 25 and 40 0C. The NaY zeolite and NaY/MVI catalytic sample were used as catalysts. The results that have been obtained weren’t satisfactory as the zeolite and the NaY/MVI sample exhibited a p-cymene yield equal to zero.