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Article

Behavior of Molybdenum–Vanadium Mixed Oxides in Selective Oxidation and Disproportionation of Toluene

1
University of Bucharest, Department of Organic Chemistry, Biochemistry & Catalysis, Faculty of Chemistry, 4-12, Blv. Regina Elisabeta, 030018 Bucharest, Romania
2
National Institute of Material Physics, 405A Atomiştilor, PO Box MG 7, 077125 Măgurele, Romania
*
Authors to whom correspondence should be addressed.
Authors with equal contribution.
Materials 2019, 12(5), 748; https://doi.org/10.3390/ma12050748
Received: 3 February 2019 / Revised: 26 February 2019 / Accepted: 28 February 2019 / Published: 5 March 2019
This study deals with the behavior of molybdenum–vanadium (Mo/V) mixed oxides catalysts in both disproportionation and selective oxidation of toluene. Samples containing different Mo/V ratios were prepared by a modified method using tetradecyltrimethylammonium bromide and acetic acid. The catalysts were characterized using several techniques: nitrogen adsorption–desorption isotherms, X-Ray diffraction (XRD), ammonia temperature-programmed desorption (TPD-NH3), temperature-programmed reduction by hydrogen (H2-TPR), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, Fourier-transform infrared-spectroscopy (FTIR) and ultraviolet-visible spectroscopies (UV–VIS). The XRD results evidenced the presence of orthorhombic α-MoO3 and V2O5 phases, as well as monoclinic β-MoO3 and V2MoO8 phases, their abundance depending on the Mo to V ratio, while the TPD-NH3 emphasized that, the total amount of the acid sites diminished with the increase of the Mo loading. The TPR investigations indicated that the samples with higher Mo/V ratio possess a higher reducibility. The main findings of this study led to the conclusion that the presence of strong acid sites afforded a high conversion in toluene disproportionation (Mo/V = 1), while a higher reducibility is a prerequisite to accomplishing high conversion in toluene oxidation (Mo/V = 2). The catalyst with Mo/V = 1 acquires the best yield to xylenes from the toluene disproportionation reaction, while the catalyst with Mo/V = 0.33 presents the highest yield to benzaldehyde. View Full-Text
Keywords: molybdena–vanadia; toluene disproportionation; toluene oxidation; p-xylene; benzaldehyde molybdena–vanadia; toluene disproportionation; toluene oxidation; p-xylene; benzaldehyde
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MDPI and ACS Style

Mitran, G.; Neaţu, F.; Pavel, O.D.; Trandafir, M.M.; Florea, M. Behavior of Molybdenum–Vanadium Mixed Oxides in Selective Oxidation and Disproportionation of Toluene. Materials 2019, 12, 748. https://doi.org/10.3390/ma12050748

AMA Style

Mitran G, Neaţu F, Pavel OD, Trandafir MM, Florea M. Behavior of Molybdenum–Vanadium Mixed Oxides in Selective Oxidation and Disproportionation of Toluene. Materials. 2019; 12(5):748. https://doi.org/10.3390/ma12050748

Chicago/Turabian Style

Mitran, Gheorghita, Florentina Neaţu, Octavian D. Pavel, Mihaela M. Trandafir, and Mihaela Florea. 2019. "Behavior of Molybdenum–Vanadium Mixed Oxides in Selective Oxidation and Disproportionation of Toluene" Materials 12, no. 5: 748. https://doi.org/10.3390/ma12050748

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