Engineering Specific Mo–O Bond Stretching to Activate Lattice Oxygen in V-Doped Bi₂MoO₆ for Enhanced Oxidative Dehydrogenation of 1-Butene

Abstract

Structural distortion has been demonstrated to regulate lattice oxygen activity, but its precise regulation has always been a thorny problem, especially for the oxidative dehydrogenation of hydrocarbons. Herein, by synthesizing a series of V-doped Bi2MoO6 catalysts, mechanistic insight into the effect of structural distortion on the catalytic activity of oxidative dehydrogenation of 1-butene was provided. Comprehensive characterizations and kinetics tests revealed that the V-doped Bi2MoO6-induced active lattice oxygen initiates 1-butene activation by abstracting the C–H bond, which is a rate-determining step. Combined with density functional theory results, an overwhelming effect of the bond length between Mo and apical oxygen atom in the MoO6 octahedron on lattice oxygen activation and butadiene formation pathway was proposed. The stretching Mo–Oapical bond elicited by V doping enhances the abstraction of hydrogen and accelerates the redox cycle. The sample with a 5% V content possesses the maximum Mo–Oapical bond length, enabling superior catalytic performance at an 87.6% 1,3-butadiene yield.

Ce Doping Boosts the Photocatalytic Activity of Ultrathin Bi2MoO6 Nanosheets for Toluene Selective Oxidation

“…The strength of two Mo–O bond peaks corresponds to the symmetric and asymmetric stretching vibrations of the MoO 6 octahedron, and the two stretching vibration modes are related to the motion of oxygen atoms perpendicular to each atomic layer. Therefore, this blue shift phenomenon results from the formation of partial oxygen defects and the distortion of the skeleton structure after Ce doping. , …”

“…Therefore, this blue shift phenomenon results from the formation of partial oxygen defects and the distortion of the skeleton structure after Ce doping. 46,47 The XPS full spectrum of 5-CBMOS reveals Bi, Mo, O, and Ce elements (Figure 3a). The high-resolution Bi 4f spectrum of 5-CBMOS can be divided into two distinct characteristic peaks located at 164.18 and 158.89 eV (Figure 3b), which correspond to the Bi 4f 7/2 and Bi 4f 5/2 of Bi 3+ , respectively.…”

Facet-Dependent Oxygen Mobility and Reaction Pathways for Oxidative Dehydrogenation of 1-Butene over Bi2MoO6

“…Orthorhombic Bi 2 MoO 6 was taken as an original structure reference, and the unit cell structure was optimized. 25 The (001) and (010) slabs of Bi 2 MoO 6 , both corresponding to a 3 × 1 × 3 supercell (162 atoms) with a half thickness of the unit cell, were constructed to simulate the 1-butene ODH process on different facets, and the slabs were isolated by a 15 Å vacuum space along the z-axis to avoid the interaction of periodic arrangement. A 3 × 3 × 2 Monkhorst−Pack k-point mesh was employed to sample the Brillouin zones of the two slabs.…”

“…21−24 Recently, researchers targeted Aurivillius bismuth molybdate (Bi 2 MoO 6 ), which exhibits better oxygen mobility and higher 1,3-butadiene yield than traditional catalysts. 25 As a layered structural semiconductor material, Bi 2 MoO 6 has been widely exploited in the photocatalysis field. 26 Most notably, the morphology and, especially, the exposed facet of Bi 2 MoO 6 change according to different solvent environments during the hydrothermal synthesis process.…”

“…30,31 Our previous work has provided a preliminary confirmation for the potential of Bi 2 MoO 6 applied in 1-butene ODH. 25 Furthermore, the oxygen mobility process should be subdivided to achieve a comprehensive understanding of the functions of oxygen species. Meanwhile, the investigation of a detailed 1-butene reaction pathway in Bi 2 MoO 6 is still restricted by theoretical and experimental evidence.…”