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采用水热晶化法,旨在合成出具有双重孔结构和双重酸性中心的L/ZSM-5复合分子筛,合成条件为:n(SiO2/Al2O3)=35,pH=12.5。借助X射线衍射(XRD)、扫描电镜(SEM)和红外光谱(IR)对其进行表征,考察反应温度对其芳构化性能的影响。XRD和IR表明,样品中同时存在ZSM-5和L分子筛结构和特征吸收峰。SEM表明,L/ZSM-5复合分子筛显示出不规则的六方棱柱面状的大颗粒,其表面附晶生长类似圆球状的小颗粒,晶界不再明显,且大颗粒表面变粗糙;反应温度为520℃时,L/ZSM-5复合分子筛催化正戊烷生成BTX的收率最高,为29.9%。合成的L/ZSM-5复合分子筛,其骨架结构、表面形貌和催化性能明显不同于其机械混合物。
Hydrothermal crystallization was used to synthesize L / ZSM-5 composite molecular sieve with double pore structure and double acid sites. The synthesis conditions were: n (SiO2 / Al2O3) = 35, pH = 12.5. The effects of reaction temperature on its aromatization performance were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and infrared spectroscopy (IR). XRD and IR show that there are both ZSM-5 and L molecular sieve structure and characteristic absorption peaks in the sample. SEM showed that the L / ZSM-5 composite molecular sieve showed irregular hexagonal prism-like large particles, the surface of the attached crystal growth similar to the spherical particles, the grain boundary is no longer obvious, and large particles surface roughening; reaction temperature At 520 ℃, the yield of BTX catalyzed by L-ZSM-5 composite zeolite was the highest (29.9%). Synthesized L / ZSM-5 composite molecular sieve, its framework structure, surface morphology and catalytic properties are significantly different from its mechanical mixture.