层状硅酸盐机械活化浸出制备多孔材料的研究

【作者】 杨武国；

【导师】 杨华明；

【作者基本信息】 中南大学 ， 材料学， 2005， 硕士

【摘要】 多孔材料以其独特的结构和性能吸引了国内外众多科学家的关注,广泛应用于催化、石油化工、环境保护等领域。传统的多孔材料均多用有机硅和硅溶胶为原料,经过水热反应或溶胶-凝胶的方法制备,原材料昂贵,易造成环境污染,难以大规模推广应用。机械活化浸出法是最新发展起来制备多孔材料的一种方法,具有原料价格低廉、工艺简单、操作容易等优点,因而具有广阔的发展前景。 本论文系统研究了以高岭土、伊利石、滑石和叶腊石为代表的层状硅酸盐的机械活化浸出行为,并以之为原料,制备出多孔材料。利用XRD、IR及SEM对制备过程进行检测表明机械研磨使得矿物晶体结构被破坏,导致粉体颗粒粒度变细,层间羟基的脱除,形成大量自由基,从而增加粉体的表面活性。通过对广西桂林产高纯滑石进行酸浸工艺试验,结合生产实际,给出滑石最佳浸出工艺条件为:研磨时间,4～6h;盐酸酸浓度,4mol/L左右;酸浸温度,60～80℃;浸出时间,1h左右;液固比,不超过20ml/g。孔性能测试表明,所制备的多孔材料,其孔形主要为狭缝孔,孔径分布在微孔区和介孔区有双峰。高岭土和伊利石制备的多孔材料具有较好的孔性能,其孔容和比表面积分别可达到0.3ml/g和300m~2/g以上。本论文还对滑石和高岭土进行了浸出动力学研究。研究发现,经过机械研磨处理后,滑石、高岭土盐酸浸出反应活化能均大幅度降低。原矿浸出时,浸出过程均属于化学反应控制;经过机械研磨活化4h后,浸出过程主要受扩散控制。这说明在机械研磨对滑石和高岭土为代表的层状硅酸盐有很好的活化效果,对浸出过程有着显著的影响。更多还原

【Abstract】 Porous material is of importance for many scientists in domestic and abroad because of its special structure and property. It was been mainly used catalyzing, oil and chemistry, environment protecting, and so on. Porous material is traditionally prepared by hydrothermal synthesis and sol-gel method using organic silicon and silicon sol as raw materials, and these methods are difficult to widely apply, because of expensive raw material and pollution. Mechanical activation and subsequent leaching is a novel and rapid developing method to prepare porous material because of its many advantages, such as cheap raw materials, and simple process easy to control.In this paper, we reported the preparation of porous silica using mechanical activation and subsequent leaching from layer silicate, such as kaolin, illite, talc and pyrophyllite. It was characterized by XRD, IR and SEM technigues. The results indicate that grinding destroyed the structure of mine crystal and the hydroxyl of layer, and reduced the particle size of powder. Plenty of activated points can be form on the surface of powder. We also did leaching technics experiment of pure talc from guangxi in this paper, and obtained the best leaching technics conditions of talc as follows: grinding time is 4 to 6 hours, concentration of hydrochloric acid is about 4mol/L, temperature of leaching is 60 to 80℃, time of leaching is about 1 hour and the ratio of hydrochloric acid volume and sample weight doesn’t exceed 20ml/g. The result of pore property indicated that our porous material possessed pore like gaps, and had two peaks in its pore size distribution curve respectively in microporous and mesoporous sections. The products from kaolin and illite have better pore property, and their pore volume and specific surface area overcome respectively 0.3ml/g and 300m~2/g. At the same time we found the leaching activation energy of talc and kaolin descended consumedly after mechanical grinding. When the original of talc and kaolin were leached, the leaching was controlled by chemistry reaction. And when the samples were ground 4 hours, diffusing course was primary in leaching. These showed mechanical grinding had prominent activation effect on leaching of layer silicate.更多还原