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Structure characterization of orthorhombic phase in MoVTeNbO catalyst by powder X-ray diffraction and XANES

Paper ID Volume ID Publish Year Pages File Format Full-Text
44076 46002 2007 6 PDF Available
Title
Structure characterization of orthorhombic phase in MoVTeNbO catalyst by powder X-ray diffraction and XANES
Abstract

The structure of the pure orthorhombic phase of the MoVTeNbO catalyst used for propane selective oxidation to acrylic acid was characterized by a combination of XANES and XRD. The vanadium K absorption pre-edge peak position due to 1s–3d transition obtained by XANES shows that average oxidation state of V is 4.1+. The Rietveld XRD analysis refined the unit cell parameters, chemical formula, and geometric arrangement of the catalyst, particularly the positions and fractional occupancies of metal atoms. The unit cell is Pba2 with a = 2.1116 nm, b = 2.6594 nm, c = 0.4007 nm. The unit formula is Mo0.555+Mo6.766+V1.524+V0.175+Te0.694+Nb1.005+Ox2− (28.34 < x < 28.69). The structure refinement of five-, six-, and seven-membered rings of MO6 (M = Mo or V) determined that Nb5+ is localized in the pentagonal channel surrounded by MO6 octahedra, that Te4+ is localized in the hexagonal channel surrounded by MO6, and that the heptagonal channel is not occupied. Results revealed that Te4+ is only localized in the hexagonal channel at 70% occupancy. Te in the catalyst proves to be highly stable.

Graphical abstractPure orthorhombic phase of MoVTeNbO catalyst prepared by hydrothermal method was characterized by combination of XANES and XRD. The unit cell is Pba2 with a = 2.1116 nm, b = 2.6594 nm, c = 0.4007 nm. The unit formula is Mo0.555+Mo6.766+V1.524+V0.175+Te0.694+Nb1.005+Ox2− (28.34 < x < 28.69). The analysis refined geometric arrangement of the catalyst, particularly the positions, fractional occupancies, and oxidation states of metal atoms. Figure optionsDownload full-size imageDownload as PowerPoint slide

Keywords
MoVTeNbO mixed oxide catalyst; XRD; XANES; Rietveld refinement; Propane selective oxidation
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Structure characterization of orthorhombic phase in MoVTeNbO catalyst by powder X-ray diffraction and XANES
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Publisher
Database: Elsevier - ScienceDirect
Journal: Applied Catalysis A: General - Volume 318, 20 February 2007, Pages 137–142
Authors
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Subjects
Physical Sciences and Engineering Chemical Engineering Catalysis
Get Full-Text Now
Don't Miss Today's Special Offer
Price was $35.95
You save - $31
Price after discount Only $4.95
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