MCM-41/MOR复合分子筛的制备及其烷烃异构化性能研究

以碱处理的MOR浆液为部分硅铝源、十六烷基三甲基溴化铵（CTAB）为模板剂，采用水热法合成了微孔-介孔复合分子筛MCM-41/MOR，并通过XRD、HRTEM、BET、Py-FTIR以及水热处理等方法对合成的复合分子筛进行了表征。结果表明，合成的复合分子筛具有微孔和介孔双重孔结构，比表面积高达567 m²/g，孔容为0.60 mL/g，平均孔径为3.26 nm，且具有较高的水热稳定性。正己烷在微反装置上的非临氢异构化反应结果表明，适宜的B酸和L酸协同构成了烷烃异构化的活性中心，催化剂表面的Ni离子在活化烷烃的同时还具有较好的酸性调变作用；与Ni-MOR、Ni-MCM-41以及HMCM-41/MOR相比，复合分子筛Ni-MCM-41/MOR由于其适宜的表面酸性和孔道结构，具有更好的异构化催化性能，正已烷转化率为34.40%，i-C₆⁰选择性提高到40.38%。

Synthesis of MCM-41/MOR composite molecular sieves and its catalytic properties for isomerization of alkane

The MCM-41/MOR composite molecular sieves with multiple micro-mesoporous structure were hydrothermally synthesized by using the alkali-treated MOR seriflux as partial silica-alumina source and cetyltrimethylammonium bromide(CTAB) as the template in self-assembly process. The synthesized samples of molecular sieves were characterized by XRD, HRTEM, BET and Py-FTIR, respectively. The results showed that the samples exhibit a hierarchical micro-mesoporous structure, large specific surface area and good hydrothermal stability as well. The isomerization performance of the composite zeolite catalyst was evaluated in a fixed bed microreactor. The results showed that the appropriate B and L acid coordinated with each other to act as the active center of alkane isomerization, while Ni species were not only active site for this reaction, but also played a good role in the modification of acidity. Compared with Ni-MOR, Ni-MCM-41 and HMCM-41/MOR, the Ni-MCM-41/MOR catalyst had better catalytic performance for isomerization reaction, the conversion of n-hexane is 34.40%, and the selectivity of i-C₆⁰ is 40.38%.