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    Please use this identifier to cite or link to this item: http://ir.lib.ncu.edu.tw/handle/987654321/3734

    Title: 含釩或鎵金屬之中孔型分子篩的合成與鑑定;Synthesis and Characterization of Vanadium- and Gallium-Substituted Mesoporous Molecular Sieves
    Authors: 潘玉鈴;Yu-Ling Pan
    Contributors: 化學工程與材料工程研究所
    Keywords: 粒子間的孔洞結構;本身的孔洞結構;中孔型分子篩;textural pore volumes;framework volumes;hysteresis loops;hexagonal mesoporous silicas (HMS)
    Date: 2002-06-12
    Issue Date: 2009-09-21 12:21:17 (UTC+8)
    Publisher: 國立中央大學圖書館
    Abstract: 中 文 摘 要 本研究為在室溫下藉由中性(S0I0)有機模板製備含釩或鎵金屬之中孔型分子篩,此含有金屬之分子篩具有催化活性的性質,我們以十二烷基胺(DDA)當作有機模板和四乙基矽酸鹽(TEOS)當作矽來源來合成出一系列不同矽釩比和矽鎵比之V-HMS和Ga-HMS,這些V-HMS和Ga-HMS材料以X光粉末繞射儀(XRD)鑑定結晶性結構,表面積及孔洞分佈由氮氣吸附-脫附儀測量,熱穩定性則利用熱重分析儀(TGA)及差式掃描熱量分析儀(DSC)所測定,晶型的外觀及孔洞的觀測則分別利用掃描式電子顯微鏡(SEM)及穿透式電子顯微鏡(TEM)觀察,釩或鎵原子的化學鍵結環境則由傅立葉轉換紅外線吸收光譜儀(FT-IR)與紫外光 / 可見光吸收光譜儀(UV-vis)加以推斷,釩或鎵元素的分析則由能量散佈光譜儀(EDS)鑑定。 V-HMS及Ga-HMS具有高表面積及均一的孔洞,因為此材料和MCM-41的結構類似,然而V-HMS及Ga-HMS和MCM-41之間最大的不同為V-HMS及Ga-HMS只具有一根XRD的繞射峰,且和MCM-41比較之下,此材料還擁有其他的性質,分別是具有較大的孔壁厚度、較小的結晶範圍及粒子間的孔洞結構變多,此外,這些材料也具有微孔洞且hysteresis loops非常明顯,此微小結晶與粒子間孔洞結構的性質使V-HMS及Ga-HMS本身的孔洞結構更完美。 本研究致力於合成出含釩或鎵金屬為催化活性中心的新中孔型分子篩,並比較其不同金屬及不同金屬含量之間的差異變化。這些新中孔型且含金屬之分子篩呈現出不規則形狀的小顆粒,這些小顆粒再聚集成較大的顆粒,Ga-HMS的BET表面積比V-HMS大,至於孔壁厚度則為V-HMS比Ga-HMS大,此意味著不管V-HMS或Ga-HMS皆有較好的熱穩定度,且這些材料粒子間的孔洞結構可高達本身的孔洞結構的20倍左右,在650 0C鍛燒下,分子篩中的有機模板即界面活性劑可被完全去除,因為這些材料含有金屬,所以在紅外線吸收光譜中有一根吸收峰在960 cm-1附近,這表示此處有Si-O-V或Si-O-Ga的鍵結,在紫外光 / 可見光吸收光譜中,V-HMS及Ga-HMS分別在255 nm及250 nm附近有吸收峰,此含釩或鎵金屬的新中孔型分子篩可應用在吸附作用、離子交換以及催化程序等方面。 ABSTRACT V-substituted and Ga-substituted hexagonal mesoporous silicas (HMS) with Si/V and Si/Ga ratios in the range of 15 ~ 200 prepared at ambient temperature by neutral (S0I0) surfanctant templating pathway are catalytically active. V-HMS and Ga-HMS silicas with various metal compositions were synthesized by using dodecylamine (DDA) as a template and tetraethylorthosilicate (TEOS) as a silica derivative. These materials were characterized by powder X-ray diffraction (XRD), N2 adsorption-desorption, thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier-transform infrared absorption spectroscopy (FT-IR), ultraviolet-visible absorption spectroscopy (UV-vis), and energy dispersive X-ray spectroscopy (EDS). V-HMS and Ga-HMS samples had high surface areas and uniform mesoporous channels, because they were similar to MCM-41. However, they differed from MCM-41 in presenting only a single peak in XRD patterns. They also possessed other characters of larger framework wall thicknesses, small crystallite domain sizes, and complementary textural mesoporosities in comparison with M41S materials. V-HMS and Ga-HMS materials had microporous pores and the hysteresis loops were obvious. These small crystallite size and complementary textural mesoporosity provided better access of the framework-confined mesopores. Our efforts in preparing V-HMS and Ga-HMS specimens by templated synthesis have led to new mesoporous silica molecular sieves with catalytically active vanadium and gallium centers. These new mesoporous metallosilicates exhibited irregularly shaped mesoscale fundamental particles which aggregated into larger particles. The specific surface areas of Ga-HMS materials were larger than those of V-HMS materials. In reference to framework wall thickness, the wall thickness of V-HMS samples was larger than those of Ga-HMS samples. All of them should have better thermal stability than MCM-41. The textural pore volumes of V-HMS and Ga-HMS specimens could be up to 20 times as large as the framework volumes. The surfactant of V-HMS and Ga-HMS could be removed completely by calcination at 650 0C. Because these materials were metal-containing, an absorption band of FT-IR at ca. 960 cm–1 was assigned to the vibration of Si-O-Me (Me is V or Ga) linkages. These V-HMS and Ga-HMS samples also showed UV-visible absorbance band at about 255 nm and 250 nm, respectively. The V-HMS and Ga-HMS specimens can be widely used in a number of adsorption, ion-exchange and catalytic processes.
    Appears in Collections:[化學工程與材料工程研究所] 博碩士論文

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