Synthesizing Beta Zeolite with Heterogeneous Seed-assisted in the Absence of Organic Template(PPT)

摘要

OrganoTemplate-Free (OTF) synthesis of zeolite with seed-assisted method is a very novel route to get zeolites. Compared with the conventional zeolites synthesized by organic species directed as templates, OTF route could effectively reduce the harmful gas for environment and also save the raw materials. In recently 5 years, Beta, RTH-13, ZSM-34, LEV, ZSM-12, ZSM-35 and ZSM-23 zeolites were synthesized in the absence of organic template by using Beta, RUB-13, ZSM-34, RUB-50, ZSM-12, ZSM-35 and ZSM-23 as seeds respectively. However, all of those successful examples were carried out with the same zeolite structures or frameworks. The growth processes show those are "core-shell" or surface crystallization mechanism. Here we choose ITQ-17, another type of zeolite Beta with the structure code number BEC, as assisted seed to synthesize Beta-I zeolite in the OTF system. According to the experiment results: ITQ-17 zeolite firstly dissolved in the mother liquid to form composite building units (CBUs); then the CBUs rebuild with the aluminosilicate species which supplied by mother liquid to form Beta-I nucleus; With the hydrothermal treatment time prolonged, Beta-I zeolite was obtained by the growth of nucleus finally. The whole growth process shows the CBUs played template roles to form Beta zeolite structure rather than the ITQ-17 seeds, which is different from the "core-shell" or surface crystallization mechanism.