(M,Na)ZSM-5沸石合成中的阳离子效应 Ⅰ.沸石成胶、成核及晶化过程的阳离子效应

THE EFFECTS OF CATIONS ON SYNTHESIS OF ZSM-5 ZEOLITES Ⅰ. EFFECTS OF ALKALI CATIONS IN NUCLEATION AND CRYSTALLIZATION OF(M, Na)ZSM-5 ZEOLITES

研究了ZSM-5沸石合成过程中(类)碱金属阳离子对沸石成胶、成核及晶化过程的影响。修正了高硅晶化平衡模型;探讨了M^+离子对此配料胶体的胶粒组成和结构的影响。发现M^+离子通过沸石配料表观pH值及本身物化性质控制沸石成核。实验结果表明,因Na^+,NH_4^+离子的竞争作用,在ZSM-5与沸石合成中发生二次成核。K^+离子的存在促进了ZSM-5沸石向α-SiO_2的转变,它是水溶液结构。

The effects of(quasi) alkali cations on the colloid formation ,uncleation and crystallization of ZSM-5 zeolites have been investigated. It was found that(quasi)alkali cations were not able to change the crystalline structure of ZSM-5 zeolites at certain conditions, but ZSM-5 zeolite gradually turned into α-SiO_2 when KCI was added to the initial Si-Al hydrogels. An equillibrium model for evaluating the alkalinity of initial hydrogels in high silica synthesis has been modified. The influence of alkali cations on the composition and structure of Si-Al hydrogels is that cations can control the nucleation of zeolite by changing the initial alkalinity of gels and through differences in their physico-chemical properties. NH_4^+ ions competed with Na^+ ions in uncleation so that, secondary uncleation occured as the composition of Si-Al gels changed during the synthesis process.