原位漫反射红外光谱研究SAPO-34分子筛的吸附性能

采用漫反射红外光谱原位考察了298－773K范围H2O，NH3和NO在SAPO－34分子筛上的吸附行为结果表明，SAPO－34对水的吸附是可逆的，对NH3和NO的吸附则是不可逆的。吸附水在623K完全脱附，脱水后的分子筛在3625－3600cm^-1出现表征桥式羟基（Si-OH-Al）的特征峰。发现SAPO－34对NH3和NO均有良好的吸附－催化活性。吸附NH3后，桥式羟基消失，位于3135，3032和1399cm^-1处在423K时出现三个吸收峰，在673K达最大，且峰高分别是SAPO－34骨架峰高的3.9,1.7和6.7倍；吸附NO后，在室温下位于1364cm^-1也观测到一强而尖锐的峰，其强度与骨架峰强度相当。对这些峰进行归属表明，吸附NH3和NO后产生了新的物种NO3^-。

The Study of Adsorption Properties of SAPO-34 Molecular Sieve by in Situ DRIFTS

The adsorption of H2O, NH3 and NO in molecular sieve SAPO-34 was studied by in situ DRIFTS at temperatures from 298 K to 773 K. The results show that the phenomenon of adsorption is reversible for H2O, but not for NH3 and NO. The water in SAPO 34 is absolutely deadsorbed at 623 K and the bridged Si-OH-Al group is observed at 3,625-3,600 cm-1. It is found that SAPO-34 displays good adsorption-catalysis activity for NH3 and NO. After adsorbing NH3, the bridged hydroxyls disappear, but three peaks appear at 3,135, 3,032 and 1,399 cm-1 at 423 K, and reach their climax at 673 K. The height of the peaks are 3.9, 1.7 and 6.7 times as much as SAPO-34 framework peak's, respectively. A strong and sharp peak is also observed at 1,364 cm-1 after NO adsorption at room temperature, and it exhibit approximately the same intensity with the framework peak. Analysis of these peaks indicate that there could produce new species NO3-.