磷酸盐辅助一步合成介孔Beta分子筛

在合成纳米Beta分子筛的体系中添加磷酸二氢钠等无机盐,通过一步晶化制备介孔Beta分子筛.纳米分子筛组装形成的二次粒子克服了传统纳米粒子难以过滤分离的问题,同时所形成的粒间介孔改善了分子在催化剂内的扩散从而提高催化反应效率.采用X射线衍射、扫描电镜、氮吸附-脱附和氨程序升温脱附等表征方法对材料进行表征,结果表明磷酸二氢钠的用量对介孔体积有很大影响.当NaH2PO4/SiO2摩尔比为0.1时,合成的材料具有较好的孔结构和酸性,并在叔丁醇与苯酚的液相烷基化反应中表现出最好的催化活性.

One-Step Synthesis of Mesoporous Beta Zeolite Using Phosphate

The addition of sodium phosphate monobasic (NaH₂PO₄) to a synthetic mixture allows a one-step synthesis of mesoporous Beta zeolite. Aggregation of the nanosized Beta zeolites allows the filtration difficulties to be overcome while the intercrystalline mesopores reduce the diffusion limitation and thus enhance the catalytic activity. The obtained Beta zeolite samples were characterized by X-ray diffraction, scanning electron microscopy, N₂ adsorption-desorption, and temperature-programmed desorption of ammonia. The amount of phosphate strongly influenced the mesopore volume of the Beta zeolites. When the molar ratio of NaH₂PO₄/SiO₂ was 0.1, the sample had good textural and acidic properties and exhibited the best catalytic activity for the alkylation of phenol with tert-butanol.