非水解溶胶—凝胶法制备锡硅、锡铝复合氧化物

发布时间：2018-05-13 09:53

  本文选题：非水解溶胶-凝胶法 + 锡硅复合氧化物　； 参考：《山西大学》2015年硕士论文

【摘要】：氧化锡的用途非常广泛,常用于电极材料和还原性气体传感器的制作,也充当固体酸催化剂和有机物氧化催化剂等。氧化锡作为活性组分,在催化应用中常与载体材料氧化硅、氧化铝复合后使用,复合后的结构、织构、形貌等特征是影响催化性能的主要因素。这些结构参数需在制备过程中进行调整和控制。制备复合氧化物的常见的化学方法有：共沉淀法、浸渍法、水热法(包括溶剂热法)和溶胶-凝胶法等。在过去的10到20年间,非水溶胶-凝胶方法逐步发展起来,成为制备金属氧化物材料强有力的工具,特别是在制备金属复合氧化物材料和有机-无机杂化材料方面,在金属氧化物纳米颗粒尺寸、形貌和晶体结构控制方面体现出优势。非水解过程的特点是聚合度高于水解过程,非水过程中有机成分的变化对其过程有重要的影响,在合成纳米氧化物颗粒的同时,形成的有机衍生物具有配位能力,这些衍生物对纳米颗粒的大小、形状、晶体结构及纳米颗粒的聚集形态等都具有重要的影响。非水过程制备复合氧化物的优势是简便,可以经一步反应就制备多组分的可控组成和织构的氧化物材料,不用使用昂贵的前驱物、反应修饰物、多步的制备程序、模板剂、超临界干燥等；可在没有表面活性剂的条件下,制备出结晶良好的金属氧化物纳米颗粒。非水过程的主要缺点是需要在无水条件进行反应,一般需要加热才能发生聚合。本研究研究内容分为两部分：(1)在课题组前期工作的基础上,改进制备锡硅复合氧化物的非水溶胶-凝胶方法。一是改变制备工艺,将水热工艺改为回流工艺,以期提高复合氧化物的产率；二是加入三氯化铁催化剂,提高非水反应过程速度和聚合度。研究这些工艺条件改变对材料结构、织构、形貌等特征的影响。(2)制备锡铝复合氧化物,考察不同种类的氧供体：Pri2O、Et2O、MeOH、EtOH对材料的结构、织构、形貌等特征的影响。获得的主要结果有：(1)在引入催化剂FeCl3条件下回流工艺制备的锡硅复合材料,比表面积和孔容明显增加,比表面积从22.58 m2/g增加到305.7m2/g,孔容从0.047 cm3/g增到0.14cm3/g,同时平均孔径明显减小,复合氧化物产率从31%提高到60%左右。催化剂FeCl3的引入促进了非水解反应过程中Sn-O-Si键的形成,有利于Sn-O-Si的过饱和析出,四方金红石结构的Sn02分散在无定形态的Si02中。(2)以乙醚和甲醇为氧供体制备的锡铝复合氧化物材料,具有较高的分子水平混合度,700℃高温焙烧条件下没有出现完整的晶体；异丙醚和乙醇为氧供体获得的复合氧化物,在600℃以上高温焙烧后出现了Sn02结晶衍射峰；其复合组分的稳定性远超其他方法获得的材料。这充分说明,非水路线能够更好地防止纳米颗粒的聚集,获得纳米尺度的氧化物和复合均匀的氧化物,这可能是由于有机副产物吸附在颗粒表面,使其在焙烧过程中不易聚集成较大的颗粒。
[Abstract]:Tin oxide is widely used in the manufacture of electrode materials and reductive gas sensors, as well as solid acid catalyst and organic oxidation catalyst. As an active component, the structure, texture and morphology of tin oxide are the main factors affecting the catalytic performance. These structural parameters need to be adjusted and controlled during preparation. The common chemical methods for the preparation of composite oxides include coprecipitation, impregnation, hydrothermal (including solvothermal) and sol-gel methods. Over the past 10 to 20 years, the non-hydrosol gel method has evolved into a powerful tool for the preparation of metal oxide materials, especially in the preparation of metal composite oxide materials and organic-inorganic hybrid materials. It has advantages in controlling the size, morphology and crystal structure of metal oxide nanoparticles. The characteristics of the non-hydrolysis process are that the degree of polymerization is higher than that of the hydrolysis process, and the changes of organic components in the non-aqueous process have an important influence on the process. These derivatives have an important influence on the size, shape, crystal structure and aggregation morphology of nanoparticles. The advantage of preparing composite oxides in non-aqueous processes is that they can be prepared by one step reaction to prepare multicomponent controllable composition and texture oxide materials without the use of expensive precursors, reaction modifiers, multistep preparation procedures, templates, etc. Metal oxide nanoparticles with good crystallization can be prepared by supercritical drying without surfactant. The main drawback of non-aqueous processes is that they need to react in anhydrous conditions. This study is divided into two parts: 1) on the basis of the previous work of the research group, the non-hydrosol gel method for the preparation of tin / silicon composite oxides has been improved. One is to change the preparation process from hydrothermal process to reflux process in order to improve the yield of complex oxides and the other is to increase the rate of non-aqueous reaction and the degree of polymerization by adding ferric chloride catalyst. The effects of these technological conditions on the structure, texture and morphology of the materials were investigated. (2) the effects of different oxygen donors, such as oxygen donor: Pri2OEt2O-MeOH2O-EtOH, on the structure, texture and morphology of the materials were investigated. The main results obtained are as follows: (1) the specific surface area and pore volume of the Sn-Si composites prepared by reflux process under the condition of introducing catalyst FeCl3 increased obviously, the specific surface area increased from 22.58 m2 / g to 305.7 m2 / g, the pore volume increased from 0.047 cm3/g to 0.14 cm 3 / g, and the average pore size decreased significantly. The yield of compound oxide increased from 31% to 60%. The introduction of catalyst FeCl3 promoted the formation of Sn-O-Si bond in the process of unhydrolytic reaction, which was beneficial to the supersaturated precipitation of Sn-O-Si. Tetragonal rutile Sn02 was dispersed in amorphous Si02. The composite oxides obtained from isopropyl ether and ethanol were calcined at high temperature above 600 鈩，

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