铝化β沸石的硅铝分布及表面酸性质

Distribution of Silicon and Aluminium Atoms as Well as Surface Acid Properties of Aluminated β Zeolite

研究了铝酸钠溶液处理对β沸石硅铝分布及表面酸性质的影响 ,通过 XRD,NH3-TPD,Pyridine-IR及 NMR表征了经 Na Al O2 溶液处理后的 Hβ沸石的表面酸性质 .结果表明 ,Hβ沸石的总酸量增加 ,B酸量和 L酸量亦增加 . Na Al O2 溶液处理对β沸石具有补铝功能 ,补铝机理为 Al(OH) - 4阴离子在 Si(0 Al) A 位发生同晶取代 .甲苯歧化与 C9芳烃烷基转移反应的催化性能考察结果表明 ,Na Al O2 溶液处理可以提高 β沸石催化剂的芳烃转化率和 (B+X)

The changes of surface properties of Hβ including distribution of silicon and aluminium atoms as well as surface acid properties after treatment by NaAlO 2 were studied. The samples were characterized by XRD, NH 3-TPD, Pyridine-IR, 29Si MAS NMR and 27Al MAS NMR. The surface properties of Hβ zeolite changed after NaAlO 2 aqueous solution treatment as follows: the total acid amount increased, Bronsted acid sites and Lewis acid sites increased. NaAlO 2 aqueous solution treatment of zeolite beta may has function of realumination at a Si(0Al) A site by an isomorphous substitution Al(OH) - 4 anions. The results of activity for disproportionation and trans-alkylation of toluene and C 9 aromatics over samples with and without NaAlO 2 solution treatment were also compared. The comparison results show that the sample with NaAlO 2 solution treatment has a higher aromatics conversion and a higher (B+X) selectivy, which indicates that the catalytic activity of zeolite beta increase as a result of NaAlO 2 solution treatment due to a change in the surface acid properties.