The nature of VOx structures in HMS supported vanadium catalysts for non-oxidative propane dehydrogenation

Vanadium was introduced to hexagonal mesoporous SiO2 (HMS) to prepare supported vanadium-based catalysts (V-HMS). Their catalytic performance in the non-oxidative propane dehydrogenation to propylene (PDH) was modulated with V surface density varying from 0.12 to 15.08V atom.nm(-2). VOx species with different structure were analyzed by UV-vis spectroscopy, NH3-TPD, H-2-TPR and XPS. High propylene space time yield of 0.73 kg.h(-1).kg(cat)(-1) and excellent regeneration behavior were achieved. Correlating VOx polymerization degree with catalytic performance, VOx aggregates, mainly in low-polyvanadate form, were established to reveal high intrinsic activity and stability in comparison with their counterparts, including isolated or/and highly polymerized VOx as well as V2O5. Temporal analysis of products (TAP) identified hydrogen formation as the rate-limiting step in the PDH reaction. In-situ DRIFTS was employed to investigate the reaction mechanism. V species containing C=C bond, i.e., VOx-C3H5, was proposed to be an intermediate of gas-phase propylene. (C) 2022 Elsevier Inc. All rights reserved.

Automated summary

Vanadium-based catalysts supported on hexagonal mesoporous SiO2 (HMS) were prepared and their catalytic performance in the non-oxidative propane dehydrogenation to propylene (PDH) was investigated. The structure and catalytic activity of VOx species, as well as the reaction mechanism, were studied. The results showed that low-polyvanadate exhibited high catalytic activity and stability.