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Crystallization of ATO silicoaluminophosphates nanocrystalline spheroids using a phase-transfer synthetic strategy for n-heptane hydroisomerization
Journal of Catalysis ( IF 7.3 ) Pub Date : 2018-06-15 , DOI: 10.1016/j.jcat.2018.06.003
Tao Yue , Wei Liu , Liyuan Li , Xiaoling Zhao , Kake Zhu , Xinggui Zhou , Weimin Yang

Changing size and shape of zeolitic crystals brings about enhanced diffusion properties and related promotion of catalytic performances. This work puts forward a phase-transfer synthetic strategy to generate ATO nanocrystalline silicoaluminophosphates spheroids under tumbling crystallization using aluminum isopropoxide dissolved in toluene and other ingredients (fumed silica/phosphoric acid/Di-n-hexylamine) dissolved in water as precursors. Toluene and aqueous phase formed a Pickering emulsion like structure during hydrothermal crystallization. Highly uniform crystalline spheroids of weighted 55 nm with strong acidity and high surface area were obtained, which exhibited a high isomer yield up to 79% in n-heptane hydroisomerization. Comparisons of product distribution and kinetic studies suggest that monomethylbranched isomer selectivity is controlled by product shape selectivity, whereas dimethylbranched isomer selectivity is affected by combined transition state and product shape selectivity. The increase in selectivity for ATO spheroids is attributed to an expansion of intrinsic reaction controlled temperature regime and an improved diffusion property.



中文翻译:

使用相转移合成策略进行正庚烷加氢异构化的ATO硅铝磷酸盐纳米晶球的结晶

沸石晶体尺寸和形状的变化带来增强的扩散性能和催化性能的相关促进。这项工作提出了一种相转移合成策略,使用溶解在甲苯中的异丙醇铝和溶解在水中的其他成分(气相二氧化硅/磷酸/二正己基胺)作为前驱体,在翻滚结晶过程中生成ATO纳米晶硅铝磷酸盐球体。甲苯和水相在水热结晶过程中形成类似Pickering乳液的结构。获得了重量很重的55 nm高度均匀的晶体球体,具有强酸度和高表面积,在正庚烷加氢异构化过程中,其异构体收率高达79%。产物分布和动力学研究的比较表明,单甲基支链异构体的选择性受产物形状选择性的控制,而二甲基支链异构体的选择性则受过渡态和产物形状选择性的综合影响。ATO球体选择性的增加归因于本征反应控制温度范围的扩大和扩散性能的改善。

更新日期:2018-06-15
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