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Controllable assembly of zeolite beta monolayers and bilayers on various substrates using the Langmuir–Blodgett technique
Microporous and Mesoporous Materials ( IF 4.8 ) Pub Date : 2015-11-30 , DOI: 10.1016/j.micromeso.2015.11.026
Honghong Xu , Baoquan Zhang , Jian Li , Xiufeng Liu

The Langmuir–Blodgett (L–B) technique was employed to fabricate the monolayers and bilayers of nano-sized beta (nano-beta) crystals, and the monolayers of micrometer-sized beta (micro-beta) crystals on various substrates including glass plate, α-Al2O3 disk, glass capillary tube, copper wire, stainless-steel tube and γ-Al2O3 tube. With respect to the methanol suspension of 1 wt.% nano-beta modified with cetyltrimethylammonium bromide (CTAB), a two-region surface pressure-area isotherm was obtained, leading to the formation of both nano-beta monolayers and bilayers with satisfactory degree of coverage (DOC) and close packing (DCP) under each transfer surface pressure. When nano-beta crystals were dealuminated, the surface pressure-area relation was reduced to the one-region isotherm, and the resulting L–B film contained aggregated areas. As for the assembly of micro-beta crystals, both methanol and sec-butanol were used as the dispersant. The resulting micro-beta monolayer was randomly oriented with the sedimentation of large truncated-square-bipyramid crystals on compression by using the methanol suspension. The use of sec-butanol as the dispersant resulted in the enhanced hydrophobicity of micro-beta crystals due to the chemical reaction of sec-butanol molecules with surface silanols, leading to the formation of c-oriented micro-beta monolayers over various substrates, and simultaneously the sedimentation of large truncated-square-bipyramid crystals did not occur. Under the structure direction of the c-oriented micro-beta monolayer in the seeded growth, the dense and preferentially c-oriented zeolite beta film could be fabricated, which could not be formed on either the nano-beta monolayer or the micro-beta monolayer with random orientation. Therefore, it would be concluded that the growth of beta crystals over the seed layer could be followed by the epitaxial growth mechanism.



中文翻译:

使用Langmuir-Blodgett技术可控制地在各种基质上组装沸石β单层和双层分子

Langmuir–Blodgett(L–B)技术用于在包括玻璃板在内的各种基板上制造纳米级β(nano-beta)晶体的单层和双层,以及微米级β(micro-beta)晶体的单层。 ,的α-Al 2 ö 3磁盘,玻璃毛细管,铜线,不锈钢管和在γ-Al 2 ö 3管子。对于用十六烷基三甲基溴化铵(CTAB)改性的1 wt。%纳米β的甲醇悬浮液,获得了两个区域的表面压力区等温线,从而形成了纳米β单层和双层,均具有令人满意的程度在每个转印表面压力下覆盖率(DOC)和密堆积(DCP)。当纳米β晶体被脱铝时,表面压力与面积的关系减小到一个区域的等温线,并且所得的LB膜包含聚集的区域。关于微β晶体的组装,甲醇和仲丁醇均用作分散剂。通过使用甲醇悬浮液,压缩后产生的微β单层随机取向,伴随着大截短的方形双锥体晶体的沉淀。c取向的微β单层在各种衬底上,并且同时没有发生大的截短的方形双锥体晶体的沉淀。在种子生长的c取向微β单分子层的结构方向下,可以制备致密且优先c取向的沸石β膜,该膜不能在纳米β单分子层或微β单分子层上形成。随机定向。因此,可以得出结论,外延生长机制可以跟随晶种层上β晶体的生长。

更新日期:2015-11-30
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