THE STUDY ON SELECTIVE CATALYTIC REDUCTION OF NO WITH NH3 OVER V2O5-WO3/TIO2 CATALYSTS

• Main Authors: Lin, Wen-hsiang, 林文祥
• Other Authors: Ienwhei Chen
• Format: Others
• Language: zh-TW
• Published: 1996
• Online Access: http://ndltd.ncl.edu.tw/handle/75859645864364299515

碩士 === 大同工學院 === 化學工程學系 === 84 === This research program is to deveiop a high performance catalyst for theselective catalytic reduction (SCR) of NOx to nitrogen with ammonia in fluegas. V2O5-WO3/TiO2 samples with compositions similar to those of commercialDe-NOx catalysts (WO3=7,8,9,10 % w/w, V2O5=<3.56 % w/w) are characterizedby TGA, XRD, TPR, TEM, SEM, EDAX, and catalytic tests in the reduction ofNOx by NH3. The V2O5-WO3/TiO2 catalysts exhibit higher reactivity than the binaryV2O5/TiO2 and WO3/TiO2 samples with the same metal loading, and temperaturewindow for the SCR reaction is greatly widened. The catalysts consist of anatase TiO2 and WO3 addition increase the size of V2O5 crystallities therebydecreasing its dispersion by TEM. Monomeric vanadyls and wolframyls and polymeric WxOy groups are observed in the samples with low vanadia loadingsthat are apparently similar to those present on the surface of the binaryoxide systems with comparable metal loadings. On increasing the vanadium loading, polyvanadate species are also formed.TPR techniques indicate a strong electronic interaction between V and W oxide species at the surface of the TiO2 support. This interaction leads to ahigher reducibility of the ternary sample with respect to the correspondingbinary ones. A synergism between V and W oxide surface species is suggested, which accounts for the high reactivity of the ternary sample in the SCR reaction. It is suggested that the higher reducibility of the samples, due tothe electronic interactions between V and W and the TiO2 support, is responsiblefor the higher reactivity of the ternary catalysts, particularly at low temperatures.