核壳结构 Beta/MCM-22双微孔复合分子筛的合成与表征

摘要

With Beta zeolite as the core crystals, core-shell Beta / MCM-22 composite zeolites with uniformmorphology were synthesized by a two-step hydrothermal method. The composite zeolites were characterized by XRD, SEM, TEM, N2-adsorption and FT-IR. The results showed the composite zeolites exhibit uniformstructured morphology; Beta and MCM-22 zeolites act as core and shell, respectively. The pore structure of Beta / MCM-22 composite zeolites was between those of MCM-22 and Beta zeolites. The amounts of mediumacidic sites and brönsted acidic sites are increased markedly (CB / CL = 13. 80) in the composite zeolites. The surface energy, Si-OH groups and surficial positive charges of Beta zeolites are enriched through Ar-H2 plasmasurface treatment , which contributes to the formation of uniform core-shell Beta / MCM-22 composite zeolites.%以 Beta 分子筛为晶核,通过二步水热晶化法成功制备了形态良好的 Beta/ MCM-22核壳结构复合分子筛。采用 X 射线衍射(XRD)、扫描电镜(SEM)、透射电镜(TEM)及 N2吸附-脱附技术等对分子筛进行了表征。结果表明,复合分子筛形态规整,Beta 与 MCM-22分别作为核壳而共生；Beta/ MCM-22复合分子筛孔结构性质介于 MCM-22、Beta 分子筛之间。在酸性分布上,复合分子筛的中强酸及 B 酸所占比例显著增加(CB / CL =13.8)。通过 Ar-H2等离子体对 Beta 分子筛进行处理,使其表面能提高并使表面正电荷富集、硅羟基增加,这是形成良好 Beta/ MCM-22核壳结构的内在原因。