Oxidative dehydrogenation of ethyl lactate to ethyl pyruvate over vanadium and iron antimonates catalysts

Abstract

The oxidative dehydrogenation of ethyl lactate to ethyl pyruvate, corresponding to the first step of a new process in the industrial production of methionine, has been investigated. Iron and vanadium antimonates were developed as catalysts, and were optimized to reach 87% conversion of ethyl lactate, with 88% selectivity to ethyl pyruvate, at only 275 °C. The catalysts were characterized before and after catalytic testing, and in situ using various techniques, including X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and XANES spectroscopy. The results show that neither the Sb 3+ /Sb 5+ nor the Fe 2+ /Fe 3+ redox couple were involved in the dehydrogenation of ethyl lactate, or in the catalysts re-oxidation. The active and selective catalytic sites correspond to surface V 5+ species. These species should not be considered as part of the bulk oxide, but as supra-surface species whose surface content is monitored with the bulk composition.

The Role of V‐Species and O‐Species on Controlled‐Hydrogen‐Reduction VOx Surfaces in Cyclohexane Oxidation

“…The V 2p3/2 peak was fitted with a Shirley background and Gaussian‐Lorenz model functions. The three peaks at 517.7 eV, 516.5 eV and 515.7 eV, respectively assigned to V 5+ , V 4+ and V 3+ species, could be confirmed based on previous literatures [10,14a,15] . The V 2p1/2 peak was determined according to a fixed ΔB.E.…”

“…Comprehensive considering the previous results and some works [4b,9–10,23] on the mechanism of hydrocarbon catalytic oxidation, the relationship between surface properties and catalytic performance were explored to understand the roles of O‐species and V‐species on CHR‐VO x surface in CHA oxidation, as displayed in Figure 6.…”

“…Vanadium species generally possess four types of valence states from +2 to +5, and under different states, the vanadium species could play various roles to determine the pathways of redox [9] . Additionally, the variety of vanadium oxygen bond also provide more possibilities for vanadium‐based catalyst to adjust the redox reaction [4b,10] . Single V−O bond, double V=O bond and the vanadium oxygen bond with vanadium under different states, these active bonds with specific lengths and angles and different redox activity were proved to be crucial sites for many reactions.…”

Dissecting the role of Bi and Ba in the catalytic efficiency of VSbBiBa/Al2O3 catalysts in oxidative dehydrogenation and oxidation of propane

“…Quantitative analyses were performed as previously described, using the SPX processing software (vision 2.2.6 Kratos). 28 The Sb 4d signal was additionally studied to ensure the presence of both Sb 3+ and Sb 5+ when necessary.…”

“…The measurements were done after catalytic testing in order to find possible correlation with catalytic properties and because previous studies showed that differences in composition could be observed when compared to before testing in this type of antimonate phase. 28,44 The surface cationic ratios calculated from the spectroscopic data are gathered in Table 5; the binding energies corresponding to the fitted peaks are listed in Table S3. † V, Sb, O and C were detected in the XPS survey scans along with Bi for the compounds containing bismuth.…”