Phase structure of V 2 O 5 /TiO 2 catalyst and catalytic behavior with removal of NO by ammonia
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Phase structure of V2O5/TiO2 catalyst and catalytic behavior with removal of NO by ammonia Xin Zhang Æ Xiaogang Li Æ Junsheng Wu Æ Renchun Yang Æ Zhihua Zhang
Received: 13 June 2009 / Accepted: 9 July 2009 / Published online: 28 July 2009 Ó Springer Science+Business Media, LLC 2009
Abstract V2O5/TiO2 catalyst with 3% (w/w) V loading has been prepared by sol–gel method. The characterization results of the catalyst structure and catalytic activity show that VOX state is strongly dependent on the calcination temperature. Little effect is found for phase structure of TiO2 support on catalytic activity. High catalytic activity in wide temperature range (240–420 °C) is observed for the catalysts calcinated at different temperatures at a space velocity of 50,000 h-1. Space velocity and alkali metal oxides strongly influence the catalytic activity of the catalyst which was calcinated at 450 °C, furthermore, the one has high tolerance to SO2 in our test conditions. Keywords V2O5/TiO2 Phase structure Catalytic activity
1 Introduction Anatase titania has been widely used in photocatalyst [1–4], solar cell [5–8] and catalyst support [9, 10] owning to its cheapness, stability and nontoxicity. In nature, titania exists as three phases, that is, brookite, anatase and rutile, and rutile is more stable than brookite and anatase thermodynamically. X. Zhang X. Li (&) J. Wu R. Yang Z. Zhang School of Material Science & Engineering, University of Science & Technology Beijing, 100083 Beijing, People’s Republic of China e-mail: [email protected]
In the previous studies of the catalysts of removal of NO by ammonia, anatase titania is widely used as catalyst support. Many approaches have been tested to improve the catalytic activity and thermal stability of the V2O5/TiO2 catalyst, for example the addition of catalytic and structural promoter such as WO3 [11–13], MO3 and rare earth elements [14], etc. Moreover, V2O5/TiO2 and V2O5–WO3/TiO2 catalysts have been prepared using sulfated TiO2 support by the method of impregnation to improve the catalytic activity due to increased acid site and to enhance thermal stability. Above all the studies of V2O5/TiO2 catalysts of removal NO by ammonia, the TiO2 support is the monophasic anatase. Besides, the addition of structural promoter is more favor of maintaining the monophasic anatase. However, in the photocatalysis, mixed-phase TiO2 revealed high activity due largely to the synergistic effect between anatase and rutile phase [15, 16]. But, it is unclear of the effect for the TiO2 support with mixed phases or monophasic rutile phase on the catalytic activity of V2O5/TiO2 catalyst with removal of NO by ammonia. In view of these, the V2O5/TiO2 catalyst with 3% (w/w) vanadia loading was prepared in nitric acid solution by sol– gel method, and then it was calcinated at various temperatures to obtain catalysts with different TiO2 phase compositions. The characterization and discussions were also made on the distribution of VOX state, the resultant effects on the structure as well as the c
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