【作者】 周德志；

【导师】 樊华；

【作者基本信息】 南昌大学 ， 环境工程， 2010， 硕士

【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。更多还原

【Abstract】 Molten salt method is recently developed as a novel synthetic method for inorganic materials. Based on one or more low melting point salts as a reaction medium, which can be dissolved by the appropriate solvent, the reaction is easily carried out via the media and pure product can be obtained after filtering and washing. Due the advantages of the simple process, low cost and synthetic temperature, short reaction time and high stability in chemical compositions, molten salt method has been widely applied in different fields, such as in the synthesis of high melting point oxide powders, electronic ceramic powders and other functional powder materials.MgCr2O4 spinel powders were synthesized in NaCl and KCl molten salt media. The effects of different raw materials, such as heating temperature, holding time and different molten salt kinds on the performances of the products have been studied. The results indicated shows that both the chromic oxide and chromic salt can be combined with crystal magnesium and calcium carbonate to produce octahedral MgCr2O4 spinel. The materials--MgCl2·6H2O、CaCO3、Cr2O3、NaCl、KCl being heated under 900℃for 5hours, the crystal size distribution of MgCr2O4 spinel becomes equal in a octahedral form and such crystals grow complete. By contrast, the crystals of MgCrO4 spinel produced by Cr(NO3)3.9H2O and CrCl3.6H2O become octahedral, incomplete and irregular in form. With increase in heating process temperature and delay in soaking time, the crystallinity of MgCr2O4 spinel improves and crystal size increases, too. And MgCr2O4 spinel growth features Ea=10.01 KJ/mol in medium of NaCl fused salt. Through molten-salt method the produced cellular MgCr2O4 spinel ceramics can be used as the carrier of automobile exhaust katalyst, standard both in form and in grid size. And the cellular MgCr2O4 spinel has the advantage of more pores, even pore width and large surface area. Therein, the celluar magne siochromic can so evenly absorb and preserve the automobile exhaust katalyst as to provide conditions for perfect exhaust purified effect.更多还原