Activation of Mo and V oxides supported on ZSM-5 zeolite catalysts followed by in situ XAS and XRD and their uses in oxydehydration of glycerol

Abstract

This paper describes the activation and catalytic performance of a multifunctional catalyst consisting of mixed oxides of vanadium and molybdenum supported on an acidic ZSM-5 zeolite. The zeolite was wet-impregnated with an aqueous solution containing a mixture of NH 4 VO 3 and (NH 4 ) 6 Mo 7 O 24 precursors at a V/(Mo+V) molar ratio of 0.6. Evolution of the phases during activation (by calcination under 20% O 2 /He) was followed by synchrotron X-ray diffraction (XRD), but detection of mixed oxides of Mo x V y O z was difficult, due to the high degree of dispersion on the zeolite surface. On the other hand, X-ray absorption spectroscopy (XAS) performed simultaneously at the Mo and V K-edges enabled confirmation of formation of the MoV 2 O 8 phase on the acidic ZSM-5 zeolite. The combination of the MoV 2 O 8 phase and the zeolite acid sites produced a highly active catalyst for gas phase glycerol dehydration-oxidation coupled reactions in which acrylic acid was the main product. The multifunctional catalyst presented only 6% of deactivation during a period of 8 h under glycerol stream, while the activities of the bulk mixed oxide and the pure ZSM-5 zeolite decreased by almost 20 and 31%, respectively.

Impact of Support (MCF, ZrO2, ZSM-5) on the Efficiency of Ni Catalyst in High-Temperature Conversion of Lignocellulosic Biomass to Hydrogen-Rich Gas

“…Other signals originate from support components. 2θ values of 11.0° (021), 14.0° (012), 15.9° (022), 18.2° (140), 23.1° (051), 24.0° (033), 24.6° (313), 29.5° (532), and 45.6° (100) were characteristic of ZSM-5 structure [34]. In the case of pure ZrO 2 and Ni/ZrO 2 , the reflexes at 30.2° (101), 35.2° (002), 50.3° (200), and 60.2° (211) confirmed the presence of t-ZrO 2 phase [35].…”

Recent Advances in Catalysis Based on Transition Metals Supported on Zeolites

“…Mixed oxides of Mo x V y O z /H-ZSM-5 were applied for gas-phase glycerol dehydration-oxidation coupled reactions in which acrylic acid was the main product. This catalyst demonstrated only 6% of deactivation during 8 h under reaction conditions, while bulk mixed oxide and the pure ZSM-5 zeolite activities decreased by 20 and 31%, respectively ( Possato et al, 2020 ).…”

In‐situ IR Spectroscopy Study of Reactions of C3 Oxygenates on Heteroatom (Sn, Mo, and W) doped BEA Zeolites and the Effect of Co‐adsorbed Water

“…The distance at 1.3 Å is assigned to Mo=O species, and the peak at 1.78 Å was identified as MoÀ OH. [34][35] The elongated bond length compared to those at room temperature indicates reduction of the Mo species.…”