374434 High Thermal Stability in Anatase Phase of Vanadium Oxide Catalyst Supported on TiO2-B/Anatase Bi-Crystalline TiO2
High thermal stability in anatase phase of vanadium oxide catalyst supported on TiO2-B/anatase bi-crystalline TiO2
Licheng Li1, Tuo Ji2, Jiahua Zhu3, Zhuhong Yang2, Xiaohua Lu2
1. College of Chemical Engineering, Nanjing Forest University, Nanjing, 210037, China
2. State Key Laboratory of Materials-oriented Chemical Engineering, Nanjing Tech University, Nanjing, 210009, China
3. Department of Chemical and Biomolecular Engineering, The University of Akron, Akron, OH 44325, USA
The thermal stability of vanadium oxide/titania catalyst is an important factor for application in selective catalytic reduction (SCR) of deNOx reactions and its further regeneration. However, the catalytic active anatase titania is inevitably transformed to low-active rutile titania under high temperature of above 500 oC. Especially doped with vanadium oxide, the phase transformation of titania will be accelerated which results in an lower anatase-to-rutile transformation temperature. The transformed rutile titania would definitely deactivate the catalytic performance of vanadium oxide/titania catalyst . Different from the general method of introducing structural additive, an isomerism effect is proposed in this work to inhibit the generation of rutile titania. TiO2-B/Anatase shell-core bicrystal titania (abbr. TiO2) reported in our previous work was chosen as catalyst support. 1.0 wt% of V2O5 was loaded by a facile impregnation process. The composition of crystal phase of V/TiO2 calcined by various temperatures was studied. It is found that the transforming temperature of rutile titania in V/TiO2 is 200 oC higher than that of conventional anatase titania loaded with vanadium oxide (abbr. V/Anatase).
XRD and Raman results show that TiO2 and Anatase has no phase transformation when the temperature is lower 600 oC. At 600~800 oC, the anatase phase of V/Anatase starts to transform to rutile phase. As for V/TiO2, TiO2-B turns into anatase and no rutile is generated. The anatase-to-rutile phase transformation of V/TiO2 occurs when the calcination temperature is higher than 800 oC. The difference in the phase transformation between V/TiO2 and V/Anatase can be attributed to the present of TiO2-B: TiO2-B is located at the outer surface of TiO2, which prevents the direct contact between anatase titania and vanadium oxide. During the thermal treatment process, TiO2-B transforms to anatase due to the acceleration effect of vanadium oxide. This process replaces the anatase-to-rutile transformation. As a result, TiO2 shows the better thermal stability than conventional TiO2 without the protective TiO2-B.
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