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Improved hydrothermal stability of silica materials prepared from ethyl silicate 40

机译：改善由硅酸乙酯制备的二氧化硅材料的水热稳定性40

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摘要

Microporous silica materials with improved hydrothermal stability were synthesized through a sol-gel process using ethyl silicate 40 as the starting silica precursor. The effects of reactants for water (hydrolysing agent), acid (catalyst) and ethanol (solvent) ratios on the microstructure of the silica matrices and their hydrothermal stability under harsh conditions (550 degrees C, 75 mol% vapour, 20 h) were systematically studied. All the calcined silica matrices were microporous and the degree of microporosity was found to increase with decreasing water and acid ratios, or increasing ethanol ratio. The most hydrothermally stable matrix was obtained by promoting the water and acid ratios whilst decreasing the ethanol ratio. A strong correlation was found between the FTIR area ratio of silanol/siloxane vibrational peaks and the initial micropore volume, and this relationship revealed that the greatest pore volume loss (>70%) occurred in the xerogels possessing a high silanol/siloxane ratio (>0.16) and a high initial micropore volume percentage (>85%). SAXS data also revealed that the most robust, hydrothermally stable silica matrices are closely associated with the formation of a more open silica microstructure derived from thermal consolidation of larger silica particles.
机译：通过使用乙基硅酸盐40作为起始二氧化硅前体，通过溶胶 - 凝胶工艺合成具有改善的水热稳定性的微孔二氧化硅材料。反应物为水（水解剂），酸（催化剂）和乙醇（溶剂）在二氧化硅基质的微观结构和苛刻的条件下的水热稳定性（550℃，75摩尔％的蒸汽，20小时）的影响比分别为系统地研究过。所有煅烧的二氧化硅基质都是微孔的，发现微孔度随着水和酸性比率降低，或增加乙醇比而增加。通过促进水和酸率而降低乙醇比而获得最多水热稳定的基质。在硅烷醇/硅氧烷振动峰和初始微孔体积的FTIR面积比之间发现了强的相关性，并且这种关系显示，在具有高硅烷醇/硅氧烷比的Xerogels中发生最大的孔隙体积损失（> 70％）（> 0.16）和高初始微孔体积百分比（> 85％）。 SAXS数据还显示出最稳健的水热稳定的二氧化硅基质与形成衍生自较大二氧化硅颗粒的热固结的更开放的二氧化硅微观结构的形成密切相关。

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  • 来源
    《RSC Advances》 |2015年第8期|共8页
  • 作者

    Wang Shengnan; Wang David K.; Jack Kevin S.; Smart Simon; da Costa Joao C. Diniz;

  • 作者单位

    Univ Queensland FIMLab Films &

    Inorgan Membrane Lab Sch Chem Engn Brisbane Qld 4072 Australia;

    Univ Queensland FIMLab Films &

    Inorgan Membrane Lab Sch Chem Engn Brisbane Qld 4072 Australia;

    Univ Queensland Ctr Microscopy &

    Microanal Brisbane Qld 4072 Australia;

    Univ Queensland FIMLab Films &

    Inorgan Membrane Lab Sch Chem Engn Brisbane Qld 4072 Australia;

    Univ Queensland FIMLab Films &

    Inorgan Membrane Lab Sch Chem Engn Brisbane Qld 4072 Australia;

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  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 化学;
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