Hydroxyl‐Mediated Non‐oxidative Propane Dehydrogenation over VO_x/γ‐Al₂O₃ Catalysts with Improved Stability

Abstract

Supported vanadium oxides are one of the most promising alternative catalysts for propane dehydrogenation (PDH) and efforts have been made to improve its catalytic performance. However, unlike Pt-based catalysts, the nature of the active site and surface structure of the supported vanadium catalysts under reductive reaction conditions still remain elusive. This paper describes the surface structure and the important role of surface-bound hydroxyl groups on VO / γ-Al O catalysts under reaction conditions employing in situ DRIFTS experiments and DFT calculations. It is shown that hydroxyl groups on the VO /Al O catalyst (V-OH) are produced under H pre-reduction, and the catalytic performance for PDH is closely connected to the concentration of V-OH species on the catalyst. The hydroxyl groups are found to improve the catalyst that leads to better stability by suppressing the coke deposition.

Facilitating the reduction of V–O bonds on VOx/ZrO2 catalysts for non-oxidative propane dehydrogenation

“…4c, d and Table S4, † the oxidation state of V is a mixture of V 5+ , V 4+ and V 3+ , which is consistent with previous results. 33,44,48 The fraction of V 3+ is 48.6% in 1VZr, which is higher than 6.6% in 1VAl.…”

“…S2a †) for all catalysts, which are at a similar level with respect to those of the VO x -based catalysts in previous studies. 10,14,18,33 In addition, we performed 120 min of the on stream reaction and studied the reaction-regeneration cycles over 1VZr ( Fig. S2b and S3 †).…”

“…It has been elucidated in the former articles that V 3+ is more active in the PDH reaction. 14,33 However, seldom detailed analyzes have been conducted to identify the structure of VO x in a reduced state and the structure-performance correlation is not clear. Therefore, in situ UV-Raman spectroscopy, which is more sensitive to the surface VO x structure, 49 was performed to monitor the evolution of V]O, V-O-V, and the V-O-support.…”

One-pot synthesis of VO x /Al 2 O 3 as efficient catalysts for propane dehydrogenation

“…The production of propylene from catalytic propane dehydrogenation (PDH) using platinum (Pt)-or chromium oxide (CrO x ) -based catalysts is practiced commercially, but the restructuring of Pt and CrO x species is also a great challenge for the stability of catalysts after regeneration [2][3][4]. Moreover, Pt-or CrO x -based catalysts are limited because Pt-based catalysts employ noble metal, while CrO x -based catalysts create pollution of the environment [5,6]. Vanadium, as a cost-effective and environmentally friendly metal, is an attractive alternative catalyst for PDH [7].…”

“…Although vanadium catalysts are mainly applied in the oxidative dehydrogenation of propane, researchers have found that they also displayed excellent catalytic performance and high stability for PDH [8,9]. For instance, Gong et al found that VO x /Al 2 O 3 catalysts prepared by the incipient wetness impregnation (IWI) method exhibited extremely high selectivity for propylene (80%) with 35% conversion of propane [5]. The surface-bound hydroxyl groups on VO x /Al 2 O 3 played an important role in catalytic performance for PDH.…”