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首页> 外文期刊>Catalysis science & technology >An enhanced nonpolarity effect of silicasupported perfluoroalkyl sulfonylimide on catalytic fructose dehydration
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An enhanced nonpolarity effect of silicasupported perfluoroalkyl sulfonylimide on catalytic fructose dehydration

机译：一个增强silicasupported的非极性效应全氟烃基sulfonylimide在催化果糖脱水

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-SO2NHSO2C4F9/CF3-functionalized silica was prepared. The preparation experiments introduced different amounts of-CH3 moieties to regulate the surface properties. Introduction of more-CH3 in the-SO2NHSO2C4F9 series brought about the materials' macroscopic hydrophobicity as expected, shown by the increased contact angle; but it was not so in the-SO2NHSO2CF3 series, which kept their hydrophilicity. In the application of fructose dehydration, the yields of HMF catalysed by the -C4F9-series catalysts were 10% higher than those by the-CF3-series catalysts at the same level of -CH3 introduced in 20% aqueous ethanol. This was due to their macroscopic hydrophobicity. However, the maximum amount of-CH3 introduced in both the-C4F9-and-CF3-series catalysts caused ca. 6% higher HMF yields, suggesting that the-CH3 moiety always promoted the dehydration. It was proposed that-CH3 changed the surface properties, even in the hydrophilic catalysts. This was confirmed by fluorescence spectrometry with pyrene as a probe molecule. An obvious enhancement of the surface nonpolarity in the introduction of a high amount of-CH3 was shown by the band III/I ratio of the spectra (0.60-0.83). The improved nonpolarity helped to repel water, both for the-C(4)F(9)and -CF3-series catalysts. In particular, for the-C4F9 series, their water-repellent ability was strengthened, and the-C4F9 group preferably repelled the produced water away from the adjacent NH site. This could weaken HMF rehydration at the acid site. The regulation effect of-CH3 along with the enhancement caused by-C4F9 thus raised the total yield of HMF to ca. 15%. The enhanced nonpolarity effect by perfluoroalkyl around the acid site should be interesting to design new solid acids with hydrophilicity-hydrophobicity balance.
机译：-SO2NHSO2C4F9 / CF3-functionalized二氧化硅准备。不同数量的32根调节表面性质。the-SO2NHSO2C4F9系列了材料的宏观疏水性由接触角增加预期,显示;但它不是the-SO2NHSO2CF3系列,这让他们的亲水性。应用果糖脱水,收益率羟甲基糠醛催化了-C4F9-series的催化剂高于10% the-CF3-series催化剂在同一水平的甲基引入20%乙醇水溶液。宏观的疏水性。量的引入the-C4F9-and-CF3-series催化剂引起ca。6%羟甲基糠醛产量的上升,这表明甲基一半都促进了脱水。that-CH3改变了表面属性,即使在亲水性催化剂。荧光光谱法与芘探针分子。引入大量非极性的32所示的乐队III /我的比率光谱(0.60 - -0.83)。帮助击退水,对c F(9)和(4)-CF3-series催化剂。the-C4F9系列,防水能力加强,the-C4F9组最好排斥产生水离开相邻的NH网站。补液的酸。效果随着增强造成的by-C4F9因此羟甲基糠醛的总收率提高到ca。15%。全氟烃基在酸网站有趣的设计新固体酸hydrophilicity-hydrophobicity平衡。

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