熔盐法制备镁铬尖晶石及在尾气净化器中的应用

发布时间：2018-06-23 08:38

本文选题：镁铬尖晶石 + 熔盐法　；参考：《南昌大学》2010年硕士论文

【摘要】：熔盐合成法是近代发展起来的一种无机材料合成方法。它采用一种或几种低熔点的盐类作为反应介质,在高温熔融盐中完成合成反应,然后采用合适的溶剂将盐类溶解,经过滤、洗涤得到合成产物。由于熔盐合成法具有工艺简单、成本低廉、合成温度低、保温时间短、合成产物的化学成分稳定均匀等优点,因而在合成高熔点氧化物粉体和电子陶瓷粉体及其它功能粉体材料等领域广泛应用。本文在NaCl、KCl熔盐介质中合成了镁铬尖晶石粉体,研究了原料种类、热处理温度和保温时间、熔盐的种类对镁铬尖晶石粉体性能的影响,同时对镁铬尖晶石应用于汽车尾气净化器载体进行了研究。研究发现,氧化铬、结晶氯化铬、结晶硝酸铬均能与结晶氯化镁和碳酸钙原料反应生成镁铬尖晶石,MgCl2·6H2O、CaCO3、Cr2O3、NaCl、KCl原料在900℃下保温5小时热处理制备的镁铬尖晶石晶体分布最为均匀,大部分为八面体形貌,晶体生长完全,Cr(NO3)3.9H2O和CrCl3.6H2O等铬盐制备的镁铬尖晶石,除了少部分呈八面体形貌外,大部分生长不完整,为形状不规则的镁铬尖晶石颗粒；随着热处理温度的升高和保温时间的延长,镁铬尖晶石晶体的结晶度有所提高,颗粒粒径增大；NaCl熔盐介质中,镁铬尖晶石晶体生长的表观活化能Ea=10.01 KJ/mol。所制备的蜂窝型镁铬尖晶石多孔陶瓷作为汽车尾气处理用催化剂载体在形状、网格尺寸方面均能达到使用标准,所制备的镁铬尖晶石多孔陶瓷具有多孔隙、孔径分布均匀、比表面积大等优点,可以很均匀地吸附和储存催化剂,为达到理想的净化效果创造了条件。
[Abstract]:Molten salt synthesis is a kind of inorganic material synthesis method developed in modern times. It uses one or more low melting point salts as the reaction medium to complete the synthesis reaction in the high temperature molten salt, then dissolves the salt in the suitable solvent, after filtration, the synthesis product is obtained. Because of the advantages of simple process, low cost, low synthesis temperature, short holding time and stable and uniform chemical composition of the product, the molten salt synthesis method has the advantages of simple process, low cost, low synthesis temperature, short heat preservation time, etc. Therefore, it is widely used in the synthesis of high melting point oxide powder, electronic ceramic powder and other functional powder materials. In this paper, magnesium-chromium spinel powder was synthesized in NaCl-KCl molten salt medium. The effects of raw materials, heat treatment temperature, holding time and molten salt on the properties of magnesium-chromium spinel powder were studied. At the same time, the application of magnesium-chromium spinel in the carrier of automobile exhaust purifier was studied. It was found that the crystal distribution of magnesium-chromium spinel can be obtained by the reaction of Cr _ 2O _ 3, Cr _ 2O _ 3 and Cr _ (No3) _ 3 with the raw materials of magnesium chloride and calcium carbonate. Most of them are octahedral, and the magnesium-chromium spinel which is prepared by Cr (No3) 3.9H2O and CrCl3.6H2O completely grows, except for a few octahedral morphology, most of them are incomplete and irregular shape magnesia-chrome spinel. With the increase of heat treatment temperature and the prolongation of holding time, the crystallinity of magnesium-chromium spinel crystal is increased, and the apparent activation energy of crystal growth of magnesia-chrome spinel in NaCl molten salt medium is increased, and the apparent activation energy (EA) 10.01 KJ / mol is obtained. The honeycomb magnesia-chrome spinel porous ceramics used as catalyst carrier for automobile tail gas treatment can meet the application standard in shape and mesh size. The prepared porous ceramics have many pores and uniform pore size distribution. Because of its large specific surface area, the catalyst can be uniformly adsorbed and stored, which creates the conditions for achieving the ideal purification effect.
【学位授予单位】：南昌大学
【学位级别】：硕士
【学位授予年份】：2010
【分类号】：TB321;U464.13

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