烃类分子在HZSM-5分子筛上的吸附扩散行为研究

以正戊烷、1-戊烯、苯为模型化合物,通过频率响应方法对它们在HZSM-5分子筛上的吸附行为进行了研究,考察了烷烃、烯烃和芳烃分子在HZSM-5分子筛上的不同吸附形式。频率响应谱图结果表明:正戊烷的响应信号最强,而烯烃和苯的响应信号比较微弱,结合吸附等温线和程序升温脱附(TPD)实验结果,可以判断正戊烷、1-戊烯、苯在分子筛上发生不同的吸附作用。正戊烷和分子筛通过范德华力作用,属于物理吸附。苯分子是通过与分子筛骨架静电场相互作用而吸附的。1-戊烯在HZSM-5上的吸附作用力最强,其吸附模式被认为是1-戊烯通过与HZSM-5上两种不同强度的酸性位相互作用完成的。

Adsorption and Diffusion of Hydrocarbons in HZSM-5 Zeolite

Adsorption and diffusion behavior of alkane,alkene and aromatics in HZSM--5 zeolites, with pentane, 1--pentene and benzene as the model of compounds, had been investigated by using the frequency response （FR） method. The FR spectra show that pentane has the strongest FR signal, while for 1--pentene and benzene, the signals were hardly detected. Combined with the results of adsorption isotherms and the TPD,it can be concluded that the interactions between the HZSM--5 and the sorbate molecules used are quite different, the interaction between pentane and the zeolite is Van der Waals force, which belongs to physisorption, while for 1- pentene and benzene, the interactions can be attributed to the strong chemiadsorption with HZSM--5 through complexation, resulting the weak FR signals.