分步晶化法合成ZSM-5/SAPO-5复合材料

通过分步晶化水热处理的方式合成了ZSM-5/SAPO-5复合材料。研究了两种分子筛凝胶的混合方式、调节ZSM-5母液的酸类型、SAPO-5凝胶组成以及晶化时间对复合材料形成的影响。实验结果表明,简单将两种分子筛的合成凝胶混合不能得到复合材料。采用H₂SO₄调节ZSM-5合成母液的pH值,在ZSM-5与SAPO-5理论质量比为3.5、SAPO-5凝胶中P₂O₅与Al₂O₃摩尔比为1.2的条件下可以得到ZSM-5/SAPO-5复合材料。但样品中含有少量无定形物质,这些无定形通过延长晶化时间并不能完全消除。

Synthesis of ZSM-5/SAPO-5 composite by two-step hydrothermal crystallization process

The composite ZSM-5/SAPO-5 molecular sieves were synthesized by two-step hydrothermal crystallization process. The effects of the mixing manner of the ZSM-5 gel and SAPO-5 gel, the acid type used to adjust the pH value of ZSM-5 mother solution, the composition of SAPO-5 gel, and the crystallization time on the synthesis of the composite were investigated. The results showed that the composite could not be obtained by simple mixing of two synthesized gels. The composite was successfully synthesized when the pH value was adjusted by sulfuric acid solution, the mass ratio of ZSM-5/SAPO-5 was 3.5 and the P_2O_5/Al_2O_3 molar ratio in the SAPO-5 gels was 1.2. The composite material contained small amount of amorphous substance, which could not be eliminated completely by extending the crystallization time.