FTIR和XPS光谱分析Co—V—O催化剂的丙烷氧化脱氢活性氧物种

doi:10.3964/j.issn.1000-0593(2009)02-0346-05

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Abstract A series of Co—V—O (meta-CoV₂O₆, pyro-Co₂V₂O₇, and ortho-Co₃V₂O₈) catalysts were prepared by microwave oxalate co-precipitation method and characterized by (XRD), TEM, BET, FTIR, XPS, H₂-TPR and conductivity measurement. The catalytic characters of the catalysts for propane oxidative dehydrogenation were investigated. The FTIR spectra of catalysts were obtained in the range of 400-1 100 cm^-1 and their major bands were assigned. The peak separation fitting of O(1s) XPS spectra was carried out and the quantity of oxygen species was calculated. The results of XRD characterization showed that pure meta-CoV₂O₆, pyro-Co₂V₂O₇, and ortho-Co₃V₂O₈ with nice structure were obtained. The TEM images demonstrated that the catalysts showed uniform particle with the mean particle size of 20-30 nm. The diagram of the relationship between electrical conductivity and oxygen partial pressure of Co₃V₂O₈ and Co₂V₂O₇ showed dσ/dP_O₂＞0, which implied that these were p-type semiconductor, and CoV₂O₆ reverse showed dσ/dP_O₂＜0, which implied n-type semiconductor. 48.12%, 47.82% and 35.24% of C₃H₆ selectivities were obtained for p-type semiconductor Co₃V₂O₈, Co₂V₂O₇ and n-type CoV₂O₆ catalysts respectively at 10% C₃H₈ conversion, and the results showed that p-type semiconductor catalysts Co₃V₂O₈ and Co₂V₂O₇ showed higher activity than n-type catalyst CoV₂O₆. The results of FTIR, XPS, H₂-TPR and conductivity measurement indicated that transferring between non-stoichiometric and lattice oxygen that easily happened in Co₃V₂O₈ and Co₂V₂O7 catalysts might promote the oxidation-reduction reaction between different valence vanadium species, and promoted the oxygen vacancy formation. Furthermore, the forming of Co—O—V bridge bond that was easy to shift between Co and V increased the mobile oxygen species of O^-₂, O^2-₂ and O^- and made the redox reaction among different valence V be realized. It is concluded that high catalytic properties of p-type semiconductor Co₃V₂O₈ and Co₂V₂O₇ can be attributed to the abundant oxygen species O^- that existed in these catalysts.

Key words：Co—V—O catalyst;Oxidative dehydrogenation;Oxygen species;XPS;Semiconductor

Received: 2007-10-02 Accepted: 2008-01-16

ZTFLH:

O643.3

Corresponding Authors: BAO Zhaorigetu E-mail: zrgt@imnu.edu.cn

Cite this article:

XU Ai-ju,LIN Qin,BAO Zhaorigetu, et al. Active Oxygen Species of Co—V—O Catalysts in Propane Oxidative Dehydrogenation Analyzed by FTIR and XPS Spectra[J]. SPECTROSCOPY AND SPECTRAL ANALYSIS, 2009, 29(02): 346-350.

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https://www.gpxygpfx.com/EN/10.3964/j.issn.1000-0593(2009)02-0346-05 OR https://www.gpxygpfx.com/EN/Y2009/V29/I02/346

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