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Applying the TPD-MS with a high sensitivity of determination, the TPD spectrum of surface oxygen of V2O5/SiO2, V2O5-MoO3/SiO2 and V2O6-P2O5/SiO2 catalysts was obtained. The surface oxygen of these catalysts can be divided into three groups according to the desorption temperature. O2- desorbs mainly from 373K. to 423K, O- from 673K to 873K and O2- at above 873K. The activation energy and frequency factor of all the three kinds of oxygen species were calculated. Based on these results, the mechanism of oxygen desorption and the influence of P2O5 and MoO3 on the properties of oxygen supply of V2O5/SiO2 catalst were investigated. MoO3 and a small amount of P2Os increase the number of supplying oxygen and increase the activity of O- species. A large amount of P2O5 increases the number of supplying oxygen and restrains the activity of O- species.
Applying the TPD-MS with a high sensitivity of determination, the TPD spectrum of surface oxygen of V2O5 / SiO2, V2O5-MoO3 / SiO2 and V2O6-P2O5 / SiO2 catalysts was obtained. The surface oxygen of these catalysts can be divided into three groups according to these desorption temperatures. O2- desorbs mainly from 373K. to 423K, O- from 673K to 873K and O2- above 873K. The activation energy and frequency factor of all the three kinds of oxygen species were calculated. Based on these results , the mechanism of oxygen desorption and the influence of P2O5 and MoO3 on the properties of oxygen supply of V2O5 / SiO2 catalst were investigated. MoO3 and a small amount of P2Os increase the number of supplying oxygen and increase the activity of O species. A large amount of P2O5 increases the number of supplying oxygen and restrains the activity of O- species.