Microporous structure in zeolite leads to diffusion limitation, which causes coke formation and is harmful to catalytic reactions. Hierarchical zeolite containing primary microporosity and secondary porosity at the meso- and macroscales has received much attention due to its enhanced mass transport. Hierarchical Y zeolites were obtained by treating NH4-Y zeolite with high-temperature calcining and acid-base leaching. The results demonstrated that the calcined zeolite showed great crystallinity after acid-base leaching. The mechanism of introduction of mesopores was demonstrated in detail. The calcination transformed framework Al to extra-framework Al and enlarged the defect by acid and alkali. The mesopores increased with the calcining temperature and holding time. The relationship between the heating rate and the removal of Al species was non-linear; a heating rate of 100°C/h exhibited good protection for the zeolite structure.

中文翻译：

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高温煅烧酸碱浸出多级孔沸石的制备

沸石中的微孔结构导致扩散受限，从而导致焦炭形成并对催化反应有害。由于其增强的质量传输，在中观和宏观尺度上含有初级微孔和次级孔的分级沸石受到了很多关注。通过高温煅烧和酸碱浸出处理NH4-Y沸石，获得了分级Y沸石。结果表明，煅烧后的沸石经酸碱浸出后结晶度较高。详细展示了介孔的引入机制。煅烧使骨架铝转变为骨架外铝，并通过酸和碱扩大缺陷。中孔随煅烧温度和保温时间的增加而增加。加热速率与Al物种去除之间的关系是非线性的；100°C/h 的加热速率对沸石结构表现出良好的保护。