Abstract: In this paper,a detailed study of diffusion properties of n⁃dodecane over three different modified Y zeolites was conducted by ZLC (Zero⁃Lengthc⁃Column) method to investigate the influence of pore structure and acidity of zeolites on diffusion.The characterization of XRD,N2 adsorption/desorption and NH3⁃TPD showed that the crystal structure of the modified Y zeolite remained unchanged and the pore structure was similar to that of the modified Y zeolite.However,the ratio of n(Si)/n(Al) decreased,the total acid content on the surface decreased,and the distribution of acid strength also changed significantly.The results of diffusion study showed that the diffusion ability of modified Y zeolite was increased,and the diffusion coefficient of n⁃dodecane in zeolite increased and the diffusion activation energy decreased with the increase of the number of medium and strong acid sites in the sample,which contributed to the improvement of catalytic performance.

Key words: Modified Y zeolite, Acidity, Pore structure, n?Dodecane, Diffusion

摘要： 选取3种改性Y沸石作为研究对象，并以未改性的Y沸石作为对比，在通过XRD、N₂吸附/脱附和NH₃⁃TPD对其晶体结构、孔结构和酸性进行表征的基础上，以正十二烷为探针分子，采用ZLC方法研究正十二烷在各种Y沸石分子筛上的扩散性能，从而分析孔结构以及表面酸性等因素对扩散的影响。结果表明，改性后的Y沸石样品与改性前比较，其晶体结构保持不变，孔结构类似，但是骨架n(Si)/n(Al)降低，表面总酸量减少，同时酸强度分布也发生了明显变化。扩散研究结果发现，改性后Y沸石的扩散能力提高，并且随着样品中中强和强酸酸中心数目的增加，正十二烷在沸石内的扩散系数增加，扩散活化能降低，有助于催化性能的提高。

关键词: 改性Y沸石, 　酸性, 　孔结构, 　正十二烷, 　扩散