频率响应法研究苯在N a Y分子筛上的吸附和扩散行为

利用频率响应技术考察了苯在N a Y分子筛上的吸附、 扩散行为, 并与TG / DTG曲线和吡啶红外等技 术相结合来分析苯在分子筛上的吸附扩散机理。结果表明, N a Y分子筛中存在两种酸性中心, 即弱B酸中心和弱L 酸中心, 且以L酸中心为主; 在3 3 3、 4 2 3K时, 苯在N a Y分子筛上有两个吸附作用力, 分别是孔填充物理吸附和π电 子相互作用两种吸附形式。逐渐接近加氢催化裂化反应的温度( 5 7 3K) 时, 苯在 N a Y分子筛上的传质仍以吸附过程 为主。但是6 2 3K时, 在 N a Y分子筛上的传质以扩散过程为主, 吸附作用力弱, 易脱附, 更易于芳烃分子在其上的扩 散, 从而提高加氢裂化反应性能。

Adsorption and Diffusion Behavior of Benzene in NaY Zeolite by Frequency Response Technique

Adsorption and diffusion behavior of benzene in NaY zeolite are studied by using the frequency response method. The TG/DTG curves and Py FTIR technique are used to analyze the adsorption and diffusion mechanism of benzene on NaY. The results indicate that NaY zeolite contains two kinds of acidic centers, namely, the weak B acid and weak L acid sites. And L acid sites are in a dominant position. There are two adsorption interactions on NaY zeolite at 333 K and 423 K, the adsorption of low frequency through the π electronic interactions and high frequency of adsorption belong to pore filling. Adsorption is still the controlling stepat 573 K. However, diffusion is the controlling step on NaY at 623 K, indicating that weak adsorption results in easier desorption and easier diffusion of aromatic molecules on NaY, there by improving the performance of the hydro cracking reaction.