The Effects of Dopants on The Physico-Chemical Properties of Vanadyl Pyrophosphate Catalysts
Vanadium phosphorus oxide (VPO) is a commercial catalyst for selective oxidation of butane to maleic anhydride. The nature of the oxidant of the doped and undoped (VOhP207 catalysts derived from (i) VPO, reaction of V20s with H3P04 in isobutanol and (ii) VPD, reaction of VOP04·2H20 with isobutano...
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| Format: | Thesis |
| Language: | English English |
| Published: |
2003
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| Subjects: | |
| Online Access: | http://psasir.upm.edu.my/id/eprint/9598/1/FSAS_2003_49_IR.pdf |
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| Summary: | Vanadium phosphorus oxide (VPO) is a commercial catalyst for selective oxidation
of butane to maleic anhydride. The nature of the oxidant of the doped and undoped
(VOhP207 catalysts derived from (i) VPO, reaction of V20s with H3P04 in isobutanol
and (ii) VPD, reaction of VOP04·2H20 with isobutanol were investigated. Metal
cations, namely of sodium, potassium, magnesium and bismuth, were added as dopants into (VO)2P2O7 lattice.
From the Scanning Electron Microscopy (SEM) and Transmission Electron
Microscopy (TEM) analysis, the catalysts which have gone through a series of redox
reaction do not produce the original morphology of (VO)2P207.
The results indicated that the addition of dopants lowered the Brunauer-Emmet-Teller
(BET) surface area of vanadyl pyrophosphate catalysts, except Bi-doped VPD
catalysts. All the doped VPO and VPD catalysts have been shown a vanadyl
pyrophosphate phase with three distinct peaks at 22.9°, 28.4° and 29.3° in X-ray
Diffraction (XRD) analysis. The Bi-doped VPO and VPD catalysts had significantly shifted the first reduction peak to a lower temperature in H2-TPR analysis. The
introduction of Bi have modified the (VOhP207 matrix and mobility of these catalyst
increased. It can be seen from TPRn analysis where VPDBil increased the selectivity
of butene and butadiene (selective products) and decreased the selectivity of CO and
C02 (unselective products). |
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