Investigation of Phosphorus Loaded V2O5/ZrO2 Catalysts for the Oxidative Dehydrogenation of Propane (ODH)

Abstract

In this study, V2O5/ZrO2 samples loaded with different wt% of V2O5, ranging between 0% and 20% (wt% = 2.5, 3.6, 7.5, 10, and 20), were prepared and studied in the dehydrogenation of 2-butanol in order to investigate their acid-basic properties and to select the most interesting sample, that was identified in the 3.6 wt%V2O5/ZrO2. Such a catalyst was modified by adding phosphate at different atomic ratios (P/V = 0.5, 1, and 2) and further characterized by XRD, SEM-EDX, ESR, UV-Vis-PIR diffuse reflectance. Tests of catalytic dehydrogenation of 2-butanol were also performed. Then, the so-prepared samples were investigated in the oxidative dehydrogenation (ODH) of propane that represents the reaction of main interest in this study. It has been shown that the introduction of 3.6 wt%V2O5 and phosphate in the zirconia matrix enhances the stability of the tetragonal structure, improves acidity, and promotes ODH activity. Compared to the unpromoted 3.6 wt%V2O5/ZrO2 catalyst, the addition of phosphate increases the overall propane conversion from 12% to 20%, and also the propylene selectivity from 54% to near 64%, in the experimental conditions F °C3H8/F°O2/F°total (cm3/min): 3.6/1.8/60 at the temperature of 500 °C. The influence of the reaction mixture on the ODH, in particular the oxygen flow rate, was addressed. Highlights: Phosphorus loaded V2O5/ZrO2 catalysts were prepared and investigated in the oxidative dehydrogenation of propane. Addition of V2O5 and phosphorus to ZrO2 stabilized the tetragonal phase with respect to the monoclinic one. Among the prepared V2O5/ZrO2 samples, the most active catalyst corresponds to 3.6 wt% of V2O5/ ZrO2, The addition of phosphorus to 3.6 wt% V2O5/ZrO2 improves acidity and selectivity to propylene. Correlation between catalysts acidity and oxidative dehydrogenation of propane was observed.