低硅铝比ZSM-48分子筛的合成与表征

Synthesis and characterization of zeolite ZSM-48 with lower n(SiO_2)/n(Al_2O_3)

通过优化ZSM-48分子筛的合成方案制备了低硅铝摩尔比的ZSM-48分子筛,并采用正交试验考察了铝源、碱源、模板剂、硅源、水等因素对ZSM-48分子筛合成的影响。采用XRD、XRF、SEM、N2吸附-脱附、NH3-TPD等对低硅铝摩尔比的ZSM-48分子筛进行了表征。结果表明:在合成体系中各组分的质量比m(NaOH)∶m(NaAlO2)∶m(H2O)∶m(RBr)∶m(SiO2)∶m(Seed)=1∶0.6∶90∶2.1∶17.5∶1的条件下制备的ZSM-48硅铝摩尔比达到了56.7;NH3-TPD结果表明,ZSM-48分子筛在360℃存在1个中强酸中心;SEM结果显示,低硅铝摩尔比ZSM-48是一种棒状和片状的聚结形态。

Zeolite ZSM-48 with lower n（SiO2）/n（Al2O3） is prepared by optimizing the factors of synthesizing zeolite ZSM-48.The effects of the amounts of aluminum source,alkali source,template,silicon source and H2O on the preparation of ZSM-48 are investigated.The obtained zeolite ZSM-48 is characterized by XRD,XRF,SEM,N2 adsorption and NH3-TPD.The results show that themole ratio of silicon oxide to aluminum oxide of ZSM-48 reach 56.7.The zeolite ZSM-48 is prepared in a mass ratio of m（NaOH） ∶ m（NaAlO2） ∶ m（H2O） ∶ m（RBr） ∶ m（SiO2） ∶ m（Seed） =1∶ 0.6∶ 90∶ 2.1∶ 17.5∶ 1.The results of NH3-TPD indicates that ZSM-48 presentes a medium strength acid site at 360℃.And zeolite ZSM-48 with lower n（SiO2）/n（Al2O3）shows a rod-like and sheet coalescence shape.