Hydrothermal synthesis of Sn-Beta zeolites in F−-free medium†,Inorganic Chemistry Frontiers

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Hydrothermal synthesis of Sn-Beta zeolites in F−-free medium†
Inorganic Chemistry Frontiers ( IF 6.1 ) Pub Date : 2018-08-21 00:00:00 , DOI: 10.1039/c8qi00672e
Hao Xu _{1,

2,

3,

4,

5} , Xudong Wang _{1,

2,

3,

4,

5} , Peng Ji _{1,

2,

3,

4,

5} , Haihong Wu _{1,

2,

3,

4,

5} , Yejun Guan _{1,

2,

3,

4,

5} , Peng Wu _{1,

2,

3,

4,

5}

Affiliation

The Sn-Beta zeolite is a unique solid Lewis acid catalyst, showing great potential in the Baeyer–Villiger oxidation reaction as well as the biomass conversion reactions. The direct hydrothermal synthesis of Sn-Beta often involved harmful F⁻ ions when using tetraethylammonium hydroxide (TEAOH) as the structure-directing agent (SDA). In this study, N-cyclohexyl-N,N-dimethylcyclohexanaminium hydroxide was used as the SDA to synthesize the Sn-Beta zeolite in F⁻-free medium. The combination of a small amount of Na⁺ ions and pure-silica Beta seeds proved to be critical for the successful synthesis of the highly crystalline Sn-Beta zeolite. The Si/Sn ratio could be tuned in the range of 60–200 by varying the gel Na/Si ratio. To obtain highly crystalline Sn-Beta zeolites, the removal of SDA molecules via calcination should be performed subsequent to NH₄⁺ ion-exchange. With a smaller crystal size and stronger Lewis acidity, the obtained Sn-Beta showed a higher catalytic activity than that synthesized in F⁻ medium with a comparable Sn content in both the Baeyer–Villiger oxidation reaction and isomerization–esterification reaction.

中文翻译：

F中的Sn-β沸石的水热合成^- -free介质†

Sn-Beta沸石是一种独特的固体路易斯酸催化剂，在Baeyer-Villiger氧化反应以及生物质转化反应中显示出巨大的潜力。的Sn-β的直接水热合成经常涉及有害F ^-使用氢氧化四乙铵（TEAOH）作为结构导向剂（SDA）时离子。在这项研究中，Ñ环己基Ñ，Ñ -dimethylcyclohexanaminium氢氧化物用作SDA来合成F中的Sn-β沸石^- -free平台。少量的Na ⁺的组合离子和纯二氧化硅Beta种子对于成功合成高度结晶的Sn-Beta沸石至关重要。通过改变凝胶Na / Si比，可以在60-200范围内调整Si / Sn比。为了获得高结晶度的Sn-Beta沸石，应在NH ₄⁺离子交换之后通过煅烧除去SDA分子。具有较小的晶体尺寸和更强的路易斯酸度，将得到的Sn-β显示出比F中合成的较高的催化活性^-介质与在拜尔-维利格氧化反应和异构化-酯化反应都相当的Sn含量。

更新日期：2018-08-21

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