Synthesis of mesoporous aluminosilicates with enhanced acidity from preformed beta zeolite
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摘要: 以微孔β沸石为硅铝源，通过碱处理和以十六烷基三甲基溴化铵为模板剂，合成了具有较强酸性的六方结构介孔分子筛材料B-MCM-41，并采用XRD、N2吸附脱附、FT-IR、27Al MAS NMR、HRTEM和水热处理等手段对其进行了结构表征，采用NH3-TPD对其进行了酸性表征。实验结果表明，B-MCM-41具有明显强于常规介孔分子筛的酸性，且在C+10混合芳烃加氢脱烷基化反应中表现出了良好的催化性能。这主要是由于碱溶液将β沸石降解为沸石结构单元，在表面活性剂作用下五元环次级结构单元被引入了介孔铝硅酸盐B-MCM-41的结构。Abstract: With alkali-treated beta zeolite as the sources of silicon and aluminum and cetyltrimethylammonium bromide (CTAB) as template, mesoporous aluminosilicates with hexagonal structure denoted as B-MCM-41 were synthesized. The structure and acidity of B-MCM-41 were characterized by XRD, N2 adsorption-desorption, FT-IR, 27Al MAS NMR, HRTEM and NH3-TPD. Compared with conventional mesoporous aluminosilicates materials, B-MCM-41 synthesized in this way exhibits enhanced acidity and higher activity for catalytic dealkylation of C+10 aromatic hydrocarbon. B-MCM-41 mesoporous structure may be built in the presence of a cationic surfactant template via the assembly of the dissolved fragments such as five member secondary structural units which are formed from the dissolution of preformed beta zeolite in a caustic solution.
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Key words:
- beta zeolite /
- mesoporous molecular sieve /
- synthesis /
- enhanced acidity /
- dealkylation
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