Synthesis, Characterization Of Nano-Oxides And Nano-metric Solid Superacids And Their Catalytic Activities For Esterification.

Nanomaterials are a new class of materials that has been making a silent revolution in the past few years. It is a foundation of the nano-technology and has aroused an extensive concern all over the world. The properties of nanomaterials show remarkable improvement or deviation from the properties exhibited by the common materials. They exhibit some special optical, magnetic, electric, or catalytic properties. These properties are attributed to the significant increase in grain boundary area due to the small grain size. Area of application that can be foreseen to benefit from the small size include quantum electronics, nonlinear optics, photonics, chemical selective sensing, and information storage and processing, adsorbents, catalysis, solar cell, magnetic recording devices, superplastic ceramics, superhard metals, metastable alloys and so on.In general, researches in nano-materials are mainly concerned with the development of methods of new syntheses and characterizations and their applications. In this thesis, sol-gel auto-combustion was employed to prepare Sm₂O₃, ZrO₂, Sni₂O₃-ZrO₂ nanoparticles and corresponding solid acid. Their structure, size and morphology were characterized by TG-DTA, XRD, XPS, TEM, AFM, IR etc.The main content is shown as following:Part One ReviewChapter One In this chapter, development and mechanism of combustion synthesis (CS), a new method to synthesize materials, were introduced. CS consists of self-propagating high-temperature synthesis(SHS) and low-temperature combustion synthesis(LCS). The difference and the similarity between SHS and LCS were also described.Chapter Two In this chapter, development, classification and synthesis of solid superacids were reviewed, and their applications in the organic synthesis reactions, especially in esterification were introduced as well.Part Two Experiments Chapter One Synthesis and characterization of nano-metric solid superacidSO^2-₄/Sm₂O₃ and its catalytic activity for esteriflcation. Section One Preparation and characterization of Sm₂O₃nano-powders by a sol-gel auto-combustion technique. Sm₂O₃ nano-powders were prepared by a novel sol-gel auto-combustion method, which was a low-temperature combustion synthesis procedure using sol-gel as precursors. X-ray diffraction (XRD), transmission electron microscopy (TEM), atomic force microscopy (AFM) were used for the sample characterization. The influences of preparation conditions on the size and morphology of the nanoparticles have been studied in detail.Section Two Preparation and characterization of SO^2-₄/Sm₂O₃ nano-powders by a sol-gel auto-combustion technique. A sort of nanometric solid super acid SO^2-₄/Sm₂O₃ was synthesized by maceration in H₂SO₄, filtration, dryness and calcination processes of substrate nanometric Sm₂O₃ The effects of preparation conditions on the catalytic activity of SO^2-₄/Sm₂O₃ were examined by the conversion of acetate acid in the esteriflcation reaction of isomyl alcohol and acetate acid. The structure of SO^2-₄/Sm₂O₃ solid super acid was analyzed by XRD, XPS and IR. In addition, TEM and AFM were also employed to measure the size and morphology of SO^2-₄/Sm₂O₃ solid super acid.Section Three Synthesis of iso-amylacetate utilizing SO^2-₄/Sm₂O₃ as catalyst Iso-amylacetate has been widely applied in chemical engineering, food and dope fields as a kind of important chemical engineering material and food additive. Concentrated H2SO4 is usually utilized as a catalyst for traditional production process of iso-amylacetate, which has some mortal bugs such as low selectivity, likely production carbonization and serious environmental pollution. In this present section, the nanosolid superacid SO^2-₄/Sm₂O₃ catalytic activity for the esteriflcation reaction of isoamyl alcohol and acetic acid was investigated in detail. A comparison of the nanosolid superacid with concentrated H2SO4 and conventionally synthesized non-nanometric superacid SO^2-₄/Sm₂O₃ indicated that the newly-synthesized product had a higher cataly...