【摘要】 分别以四乙基氢氧化铵和十六烷基三甲基溴化铵作为微孔相和介孔相的模板,采用两步晶化法制备了4种具有不同硅铝比,含微孔和介孔双模孔结构的Beta/MCM-41复合分子筛.采用X射线衍射、N2吸附-脱附对Beta/MCM-41复合分子筛的结构进行了表征,利用吡啶吸附红外光谱(Py-FTIR)以及正庚烷裂解作为探针反应,对不同硅铝比的Beta/MCM-41复合分子筛的酸量和催化性能进行了研究.实验结果表明,随投料硅铝比的增加,复合分子筛介孔相有序性逐渐提高,微孔相的结晶度逐渐减小,酸量降低,正庚烷裂解的转化率明显下降.说明该复合分子筛的性能可随硅铝比的变化进行调变.更多还原

【Abstract】 The composite molecular sieves Beta/MCM-41 with different ratios of SiO2/Al2O3 were hydrothermally synthesized by two-step crystallization with tetraethylammonium hydroxide and cetyltrimethylammoniumbromide as templates.The structure of products was characterized by XRD,N2 adsorption/desorption.The acid content and catalytic performance of composite molecular sieves Beta/MCM-41 with different ratios of SiO2/Al2O3 were investigated by Py-IR and cracking reaction of n-heptane,respectively.It was found that the order of mesoporous phase in composite molecular sieves was improved with the increasing of SiO2/Al2O3 ratio.However the crystallinity of microporous phase,acid content and the percent conversion of n-heptane was decreased with the increasing of SiO2/Al2O3 ratio.It was indicated the performance of composite molecular sieves could be modified by changing the ratio of SiO2/Al2O3 in synthesis process.更多还原