REACTIVITY AND PHYSICOCHEMICAL CHARACTERIZATION OF V2O5-WO3/TIO2 DE-NOX CATALYSTS
REACTIVITY AND PHYSICOCHEMICAL CHARACTERIZATION OF V2O5-WO3/TIO2 DE-NOX CATALYSTS
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DOI：
10.1006/jcat.1995.1193
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发表时间：
1995-08-01
影响因子：
7.3
通讯作者：
BREGANI, F
中科院分区：
文献类型：
--
作者：
ALEMANY, LJ;LIETTI, L;BREGANI, F
采用XRD、比表面积和孔径分布、傅里叶变换红外光谱、激光拉曼光谱、W-vis漫反射光谱、电子顺磁共振光谱和NH_3还原NOx的催化试验对组成与商业脱硝催化剂相似（WO_3约为9%w/w，V_2O_5 <3%w/w）的V_2O_5-WO_3/TiO_2样品进行了表征。在相同金属负载量下，V2 O 5-WO 3/TiO 2催化剂的反应活性高于V2 O 5/TiO 2和WO 3/TiO 2催化剂，SCR反应的温度窗口大大拓宽。该催化剂由TiO_2组成，其形态性质与（V + W）表面覆盖率低于1的WO_3/TiO_2非常相似。在具有低氧化钒负载量的样品中观察到单体氧化钒和钨以及聚合物WwOy基团，其显然类似于具有可比金属负载量的二元氧化物系统的表面上存在的那些。随着钒负载量的增加，也会形成多钒酸盐物种。EPR，FTTR，FT-拉曼光谱和紫外-可见光谱技术表明在TiO 2载体的表面的V和W氧化物物种之间的强电子相互作用。这种相互作用导致相对于相应的二元样品的三元样品的更高的还原度。V和W氧化物表面物种之间的协同作用的建议，这占在SCR反应的三元样品的高反应性。有人建议，较高的还原度的样品，由于V和W和TiO 2载体之间的电子相互作用，是负责较高的反应性的三元催化剂，特别是在低温下。(C)出版社：Academic Press
V2O5-WO3/TiO2 samples with compositions similar to those of commercial de-NOx catalysts (WO3 similar to 9% w/w, V2O5, < 3% w/w) are characterised by XRD, surface area and pore size distribution, Fourier transform infrared, laser Raman, W-vis diffuse reflectance, electron paramagnetic resonance spectroscopies, and catalytic tests in the reduction of NOx by NH3. The V2O5-WO3/TiO2 catalysts exhibit higher reactivity than the binary V2O5/TiO2 and WO3/TiO2 samples with the same metal loading, and the temperature window for the SCR reaction is greatly widened. The catalysts consist of anatase TiO2 and their morphological properties closely resemble that of WO3/TiO2 for (V + W) surface coverages lower than one. Monomeric vanadyls and wolframyls and polymeric WwOy groups are observed in the samples with low vanadia loadings that are apparently similar to those present on the surface of the binary oxide systems with comparable metal loadings. On increasing the vanadium loading, polyvanadate species are also formed. EPR, FTTR, FT-Raman, and UV-vis techniques indicate a strong electronic interaction between V and W oxide species at the surface of the TiO2 support. This interaction leads to a higher reducibility of the ternary sample with respect to the corresponding binary ones. A synergism between V and W oxide surface species is suggested, which accounts for the high reactivity of the ternary samples in the SCR reaction. It is suggested that the higher reducibility of the samples, due to the electronic interactions between V and W and the TiO2 support, is responsible for the higher reactivity of the ternary catalysts, particularly at low temperatures. (C) 1995 Academic Press, Inc.