To investigate faster crystallization of zeolite beta by the dry-gel conversion method, the local structure of the dry gel before synthesis was quantitatively evaluated using in situ Raman spectroscopy during the drying process. The dry gel prepared from Si and Al sources, and tetraethylammonium hydroxide solution was crystallized after several hours by the dry-gel conversion method. The conformational change of TEA⁺ cations was observed during the drying process by the deconvolution of the spectrum, and the conformational change was larger than that during the synthesis process. The rate of conformational change was increased with the drying temperature, and the apparent activation energy was estimated to be 68.2 kJ/mol. The generation and transformation of double three-membered silicate rings (D3Rs) and 4-2 type secondary building units (SBUs), which are essential for the crystallization of zeolite beta, were observed during the drying process. The transformation from D3R to 4-2 SBU in the dry gel during drying process could be confirmed quantitatively by the difference of the time variation for the amounts of these silicate building units estimated by in situ observation.

中文翻译：

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用于沸石 β 合成的干凝胶中局部结构的原位拉曼光谱分析

为了通过干凝胶转化法研究沸石 β 的更快结晶，在干燥过程中使用原位拉曼光谱定量评估了合成前干凝胶的局部结构。由Si源和Al源制备的干凝胶和四乙基氢氧化铵溶液在几小时后通过干凝胶转化法结晶。^{TEA +}的构象变化通过光谱解卷积观察干燥过程中的阳离子，构象变化比合成过程中大。构象变化率随着干燥温度的增加而增加，表观活化能估计为 68.2 kJ/mol。在干燥过程中观察到双三元硅酸盐环 (D3Rs) 和 4-2 型二级结构单元 (SBUs) 的生成和转变，这些对于沸石 β 的结晶至关重要。干燥过程中干凝胶中从 D3R 到 4-2 SBU 的转变可以通过原位观察估计的这些硅酸盐构建单元的量的时间变化差异来定量证实。