纳米富铝β沸石的合成与表征

Synthesis and characterization of nanocrystallite aluminium-rich beta zeolite

  • 摘要: 以低硅铝比焙烧后的硅铝胶固体为初始原料,在含F-近中性与低含水量体系下晶化合成出相对高结晶度的纳米富铝β沸石。实验考察了合成条件、硅铝胶焙烧对晶化产物的影响和晶化过程中Al配位状况变化,并采用XRD、XRF、SEM/TEM、27Al MAS NMR物化方法对晶化产物进行表征。结果表明,含F-离子、H2O/SiO2摩尔比为2.4~6.0以及高温焙烧硅铝胶有利于合成高结晶度的纳米富铝β沸石;硅铝胶固体焙烧后能产生易于转化为β沸石晶核的Al四配位结构,而部分六配位Al在晶化过程中缓慢溶入β沸石晶核中而最终生成纳米富铝β沸石。

     

    Abstract:  The aluminium-rich beta zeolite with relatively high crystallinity and nanometer size was synthesized in the neutral system, in which the lower water content and F- anion were involved. The solid aluminosilicate gel was prepared as the original materials. The effects of synthesis conditions and the calcined aluminosilicate gel properties on the crystallization products were investigated. The evolvement of Al coordination situation had also been studied during crystallization process. The crystallization products were determined by means of XRD, XRF, SEM, TEM, 27Al MAS NMR methods. The results showed that the crystallization conditions involved F- anion and H2O/SiO2 mol ratio 2.4~6.0 as well as solid aluminosilicate gel calcined at high temperature contributed to aluminium-rich beta zeolite with relative higher crystallinity and nanometer size. The solid aluminosilicate gel was calcined to lead to production of four-coordinated aluminium subjected to being transformed into beta zeolite framework. The part of six-coordinated aluminium slowly dissolved into the crystal nuclei during crystallization period. The result led to get the nanometer aluminium-rich beta zeolite at last.

     

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