The speciation of vanadium in initial aqueous NH₄VO₃ solutions as a function of pH and concentration, in supernatant and in wet solids were investigated by ⁵¹V static and MAS NMR. Two series of VSiBeta zeolite catalysts were prepared by a two-step postsynthesis procedure at pH = 2.5 and 6. ⁵¹V static and MAS NMR, ⁵¹V 3Q MAS NMR, DR UV-vis, XPS and EPR allowed determining the state of vanadium in both series of catalysts. The catalytic activity of VSiBeta catalysts in SCR of NO strongly depended on the state of the vanadium present. The V-single site V_1.0SiBeta(I) and V_1.4SiBeta(I) catalysts with isolated pseudo-tetrahedral V(V) were active in SCR of NO with NH₃ process, with maximum NO conversion about 75 % at 773 K for V_1.4SiBeta(I). In contrast, V_1.0SiBeta(II) and V_7.5SiBeta(I) catalysts containing pseudo-octahedral V(V) were much less active in SCR of NO and high amount of undesired N₂O was produced.

通过⁵¹ V静态和MAS NMR研究了初始NH ₄ VO ₃水溶液中，上清液和湿固体中钒的形态与pH和浓度的关系。通过在pH两步后综合程序制备两个系列VSiBeta沸石催化剂= 2.5和6. ⁵¹ V静态和MAS NMR，⁵¹ V 3Q MAS NMR，DR的UV-vis，XPS和EPR允许确定钒的状态两个系列的催化剂。VSiBeta催化剂在SCR的NO中的催化活性在很大程度上取决于存在的钒的状态。V单工位V _1.0 SiBeta（I）和V _1.4具有分离的拟四面体V（V）的SiBeta（I）催化剂在采用NH ₃工艺的SCR的NO SCR中具有活性，V _1.4 SiBeta（I）的最大NO转化率在773 K下约为75％。与此相反，V _1.0 SiBeta（II）和V _7.5含伪八面体V（V）SiBeta（I）催化剂为少得多的活性中的NO和不期望的N个高量的SCR ₂ O的产生。