Synthesis of Hollow Nanocubes and Macroporous Monoliths of Silicalite-1 by Alkaline Treatment
Synthesis of Hollow Nanocubes and Macroporous Monoliths of Silicalite-1 by Alkaline Treatment
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DOI：
10.1021/cm401739e
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发表时间：
2013-11-12
影响因子：
8.6
通讯作者：
Guo, Xinwen
中科院分区：
文献类型：
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作者：
Dai, Chengyi;Zhang, Anfeng;Guo, Xinwen
一种涉及在氢氧化四丙基铵（TPAOH）溶液中对Silicalite - 1进行脱硅和重结晶的简单策略被成功开发，用于制备中空沸石纳米立方体和三维大孔沸石整料。通过用OH⁻控制硅的浸出，在Silicalite - 1晶体中引入了大的空隙，并且通过硅与TPA⁺的重结晶形成了薄的完整外壳。通过简单地调节母体Silicalite - 1的尺寸，纳米立方体的尺寸可以容易地从约150 nm控制到约600 nm。除了作为模板提高中空Silicalite - 1的产率的功能外，吸附在沸石上的TPA⁺保护了发生重结晶的母体晶体表面。中空沸石壳中中孔和/或大孔的尺寸可以通过改变添加到TPAOH溶液中的竞争性Na⁺吸附剂的量来控制。此外，当向TPAOH溶液中添加电解质（如NaCl）时，可以形成三维大孔沸石整料。当该样品用作铁基催化剂的载体用于二氧化碳加氢制烃时，二氧化碳的转化率和C₅⁺及更高级烃的选择性都得到了提高。
A simple strategy involving desilication and recrystallization of silicalite-1 in tetrapropylammonium hydroxide (TPAOH) solution was successfully developed to prepare hollow zeolite nanocubes and three-dimensionally macroporous zeolite monoliths. Large voids were introduced to silicalite-1 crystals by controlled silicon leaching with OH- and thin intact shells were formed by the recrystallization of silicon with TPA(+). The size of nanocubes could be easily controlled from similar to 150 nm to similar to 600 nm by simply adjusting the size of parent silicalite-1. Apart from template function to increase the yield of hollow silicalite-1, TPA(+) adsorbed on the zeolite protects the parent crystal surface where the recrystallization occurred. The size of the mesopores and/or macropores in the hollow zeolite shell can be controlled by varying the amount of competitive Na+ adsorbent added to the TPAOH solution. Furthermore, three-dimensional macroporous zeolite monoliths can be formed when an electrolyte, such as NaCl, was added to the TPAOH solution. When the sample was used as the support for iron-based catalyst for hydrogenation of CO2 to hydrocarbons, both the conversion of CO2 and the selectivity of C-5(+) higher hydrocarbons were improved.