| Summary: | 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.
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