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首页> 外文学位 >Molecular Compositions, Structures, and Acid Properties of Silica-alumina, Silicate, and Aluminosilicate Catalysts and Supports.
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Molecular Compositions, Structures, and Acid Properties of Silica-alumina, Silicate, and Aluminosilicate Catalysts and Supports.

机译：二氧化硅-氧化铝，硅酸盐和铝硅酸盐催化剂和载体的分子组成，结构和酸性质。

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摘要

Silica-aluminas, silicates, and aluminosilites (zeolites) have been widely used as heterogeneous catalysts and supports, because compared to homogeneous catalysts, their solid-acid properties are often desirable for selectivity and separation reasons. However, despite decades of use, much remains unknown with regard to the molecular origins of their acidities and how they may be controlled. For zeolites, although the molecular origins of their acidities are known, the molecular interactions that direct the formation of crystalline frameworks are poorly understood, limiting the structures and compositions, and thus acid and/or adsorption properties, which can be obtained. The molecular origins of acidity of silica-aluminas, on the other hand, remain heavily debated, prohibiting predictive control of their acid properties. A greater understanding of the local compositions and structures of solid acid sites is required to develop predictive syntheses of solid acid catalysts or supports with tunable catalytic and/or adsorption properties.;Advanced nuclear magnetic resonance (NMR) techniques, in conjunction with X-ray diffraction (XRD) and infrared (IR) spectroscopy, provide insights on the local compositions, structures, and interactions among the various components of silicates, aluminosilicates, and silica-aluminas. For example, the roles of structure-directing and mineralizing agents and their interactions with silicate species during zeolite synthesis can be determined using one- and two-dimensional NMR techniques. Such interactions provide insight on zeolite nucleation and subsequent crystallization that are expected to aid in the development of new predictive synthesis protocols for zeolites with tunable surface properties. For amorphous silica-aluminas, the combination of probe molecule adsorption, catalytic testing, and NMR and IR characterization is vital for determining the molecular origins of their surface acidities. Adsorption of basic probe molecules, in conjunction with NMR and IR spectroscopy, allow for the compositions, structures, strengths, and distributions of surface acid sites on silica-aluminas to be determined. Such detailed understanding of acid sites is used to establish correlations among the Bronsted and Lewis acidities as well as correlations between the bulk and chemical properties of silica-aluminas. Ultimately, the used of advanced spectroscopic techniques has allowed for greater understanding of solid acidity, which can be used to aid in the development of new solid acid catalysts and supports.
机译：二氧化硅-氧化铝，硅酸盐和铝硅酸盐（沸石）已广泛用作非均相催化剂和载体，因为与均相催化剂相比，出于选择性和分离的原因，通常需要它们的固体酸性质。然而，尽管使用了数十年，但关于其酸度的分子来源以及如何控制它们仍然未知。对于沸石，尽管已知其酸度的分子起源，但是对指导结晶骨架形成的分子相互作用的了解很少，从而限制了结构和组成，从而限制了可获得的酸和/或吸附性能。另一方面，硅铝酸度的分子起源仍然有很多争论，这阻止了对其酸性质的预测控制。需要深入了解固体酸位的局部组成和结构，以开发具有可调节催化和/或吸附特性的固体酸催化剂或载体的预测性合成。先进的核磁共振（NMR）技术与X射线结合衍射（XRD）和红外（IR）光谱，可提供有关硅酸盐，铝硅酸盐和二氧化硅-氧化铝的各种成分之间的局部组成，结构和相互作用的见解。例如，可以使用一维和二维NMR技术确定在沸石合成过程中结构导向剂和矿化剂的作用及其与硅酸盐物质的相互作用。这种相互作用提供了关于沸石成核和随后结晶的见识，这些预期将有助于开发具有可调表面性质的沸石的新预测合成方案。对于无定形二氧化硅-氧化铝，探针分子吸附，催化测试以及NMR和IR表征的结合对于确定其表面酸度的分子来源至关重要。碱性探针分子的吸附，结合NMR和IR光谱，可以确定二氧化硅-氧化铝表面酸位的组成，结构，强度和分布。对酸位的这种详细理解用于建立布朗斯台德和路易斯酸度之间的相关性，以及二氧化硅-氧化铝的体积和化学性质之间的相关性。最终，先进光谱技术的使用使人们对固体酸度有了更深入的了解，可以用来帮助开发新的固体酸催化剂和载体。

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  • 作者

    Shayib, Ramzy Mohammed.;

  • 作者单位

    University of California, Santa Barbara.;

  • 授予单位 University of California, Santa Barbara.;
  • 学科 Chemistry Inorganic.;Engineering Chemical.
  • 学位 Ph.D.
  • 年度 2011
  • 页码 211 p.
  • 总页数 211
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

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