Tmperature programmed techniques study on the nature of the oxidant in/on V2O5catalyst ? |
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| Authors: | Yun Hin Taufiq-Yap and Kenneth C Waugh |
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| Institution: | (1) Department of Chemistry, Universiti Putra Malaysia,, 43400 UPM Serdang, Malaysia;(2) Department of Chemistry, University of Manchester,, PO Box 88, Manchester M60 1QD, United Kingdom |
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| Abstract: | Summary The nature of the oxidising species in/on a vanadium pentoxide (V2O5) catalyst has been studied using a combination of transient techniques: (i) Temperature programmed desorption (TPD), (ii)
Temperature programmed reduction (TPR), (iii) Temperature programmed oxidation (TPO) and (iv) Temperature programmed reaction
(TPRn). Chemisorbed oxygen was found not to exist on a fully oxidised V2O5 catalyst by TPD. The TPR in CO over V2O5 catalyst gave three peak maxima at 930, 982 and 1043 K, indicating that three types of kinetically different oxygen states
exist in/on the catalyst. Reoxidation of the CO reduced V2O5 catalyst by N2O resulted in the quantitative replacement of the lattice oxygen. A further reduction of the N2O reoxidised catalyst gave a significantly different TPR profile compared to the original material suggesting that a less
crystalline material had formed. The presence of phosphorus in (VO)2P2O7 was found to labilise the lattice oxygen. |
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