溶液雾化法制备镍钴精细粉体材料理论与工艺研究

发布时间：2018-02-12 15:57

本文关键词： 溶液雾化法氧化亚镍四氧化三钴氧化亚钴金属钴粉合金粉末触媒理论与工艺　出处：《中南大学》2010年博士论文　论文类型：学位论文

【摘要】：镍钴类过渡金属精细粉体材料,包括单一金属氧化物粉末、单质粉末、人造金刚石领域用作粉末触媒的金属合金粉末等,是一类具有特殊结构和性能的重要功能材料,广泛应用于电子信息、清洁能源、石油化工、精细陶瓷等现代基础工业领域及国防军工高端领域。探索各种新的精细粉体制备方法是粉体材料重要研究方向。本研究开拓了一种溶液雾化制备有色金属精细粉体材料的新方法,制备出组成准确均匀化、微观形貌超细可控化、宏观性质功能优异化的精细粉体,克服了传统制备方法的缺陷,可满足相关行业对高性能精细粉体多样性和苛刻性要求,具有重要的理论价值和实际意义。本文首先提出和设计了一种溶液雾化法制备镍钻系列精细粉体材料的新工艺,并为此设计建立了专门实验装置以及系统开展了有关理论与工艺研究。本研究取得的主要成果有：一、设计了溶液雾化法制备精细粉体新工艺,建立了一套溶液雾化法制备精细粉体的专用实验装置。采用建立的装置系统,不但可实现有色金属粉体材料精细制备,而且可实现物料的闭路循环利用。二、对溶液雾化法制备NiO反应过程热力学进行了研究,确定了反应进行的热力学条件,利用自行建立的溶液雾化制粉装置开展实验,成功制备得到单一高纯NiO精细粉体。探讨了温度、载气种类、溶液浓度、雾化压力、溶液体系对NiO粉体样品组成、结构、微观形貌的影响,研究发现采用惰性载气(氮气)或氧化性载气(空气、氧气)均能制备得到单一NiO精细粉体；温度对原料转化率及样品物化指标产生重要影响；溶液浓度、雾化压力也对样品粒度形貌产生影响；采用硝酸盐体系易制得微米级空心球NiO粉体、硫酸盐体系可制得微米级多孔NiO粉体。当采用氯化盐为溶液溶质时,易得到高品质亚微米级NiO密实粉体粒子,但颗粒粒径不符合ODOP机理。在以空气为载气、氯化镍为溶液溶质、温度为800℃、溶液浓度为1.0mol·L-1、雾化压力为0.10 MPa的优化条件下,制备所得样品为形貌规则立方体、粒子均匀性好、平均粒径约为0.4μm、镍含量77.1%、余氯含量0.08%、松装密度值为0.63 g/cm3的高纯度NiO精细粉体。三、对溶液雾化法制备钴氧化物反应过程热力学进行了研究,确定了反应进行的热力学条件,溶液雾化法制备钴氧化物粉体过程,适用逐级转变规则,利用自行建立的溶液雾化制粉实验装置开展实验,成功制备了高纯C0304及CoO精细粉体。探讨了温度、载气种类对制备C0304性能影响,温度对样品纯度、结构、微观形貌产生重要影响,以压缩氧气为载气,能有效改善产物结晶性。在空气为载气、氯化钴溶液浓度为2.0mol·L-1、载气压力为0.25 MPa、温度为750℃的优化条件下,所得样品为高纯度的Co304精细粉体。研究发现雾化压力、气液比、溶液浓度均对产物含氯量产生明显影响；反应不完全、粉体对氯化氢的吸附行为及存在逆反应是降低原料转化率的主要原因；气固分离过程采取保温措施产物含氯量能有效降低；研究发现溶液雾化法制备所得C0304样品具有较好的超电容行为,其比电容可达到103.5 F·g-1。溶液中添加还原性化合物乙醇、尿素或者采用非氧化性气体为载气,有利于CoO的生成。在温度900℃、氯化钴溶液浓度0.5mol·L-1、雾化压力为0.08 MPa、以高纯氮气为载气、溶液中添加少量乙醇的条件下,制备得到了结晶性好、粒度介于亚微米尺度的正八面体高纯CoO精细粉体。四、以氯化钴溶液为原料,基于非氢还原的溶液雾化技术,开展直接制备金属钴粉试验。研究发现高纯氮气适宜用作雾化载气,乙醇可作为制备过程中的有效还原剂,乙醇加入量、温度、溶液浓度及载气压力均对钻粉制备过程产生影响。在以高纯氮气为载气、温度为800℃、乙醇：水溶液比为1：1(V/V)、溶液浓度为0.5mol·L-1、雾化压力为0.08 MPa的条件下,成功制备得到FCC晶体结构的金属钴粉。对样品的Zeta电位测试发现,制备所得钴粉具有较好的分散性与稳定性。采用溶液雾化法直接制备金属钴粉过程中,同样适用逐级转变规则,即从钴氧化物到金属钻粉需经由逐级还原过程。五、开展溶液雾化法制备粉末触媒实验,按化学计量比配制溶液,控制反应条件,采用溶液雾化法分别成功制备得到组成为Ni7Co3、Fe7Ni3、FeNi3、Ni70Mn25Co5的合金粉末触媒,对应样品的微观形貌为：由纳米粒子堆积而成的蚕茧状、由纳米膜组成的疏松花状球形、由纳米纤维组成的海胆形、由纳米片组成的鳞片簇。六、以溶液雾化法制备NiO及Co304粉体过程为对象,开展过程动力学研究,发现制备过程均由三个动力学机理完全不同的连续步骤组成,即溶质结晶析出、溶质脱水与分解、产物晶体生长。采用Doyle方程和Coats-Redfern方程联合推断相应溶质脱水与反应步骤的动力学机理,并求出了相应的动力学方程式。对于产物晶体生长步骤,相应求出了NiO及Co3O4晶粒生长速度对温度的动力学方程。
[Abstract]:Nickel - cobalt transition metal fine powder material , including single metal oxide powder , elemental powder , metal alloy powder used as powder catalyst in the field of powder catalyst , is a kind of important functional material with special structure and properties . It is widely used in the fields of modern basic industry such as electronic information , clean energy , petrochemical industry , fine ceramics , etc . In this paper , a new process for preparing nickel - drill series fine powder material by solution atomization is put forward and designed . A special experimental device and a system have been developed for this design . The main results of this research are as follows : firstly , a new process for preparing fine powder by solution atomization is designed , a set of special experimental equipment for preparing fine powder by using a solution atomization method is established , and a device system is adopted , so that the fine preparation of the non - ferrous metal powder material can be realized , and the closed cycle utilization of the material can be realized . In this paper , the thermodynamics of NiO reaction was studied by solution atomization method . The thermodynamic conditions of reaction were determined . The effect of temperature , carrier gas species , concentration of solution , atomization pressure and solution system on sample size morphology was studied . The process of preparing cobalt oxide powder by solution atomization was studied . The thermodynamic conditions of reaction were determined . The process of preparing cobalt oxide powder was determined by solution atomization . The effect of temperature and gas - liquid ratio and solution concentration on the yield of product were studied . The results showed that the concentration of oxygen - carrier gas was 2.0mol 路 L - 1 , the carrier gas pressure was 0 . 25MPa , the concentration of cobalt chloride solution was 2.0mol 路 L - 1 , the atomization pressure was 0 . 08 MPa , and high purity nitrogen was used as carrier gas . The direct preparation of cobalt powder was carried out by using cobalt chloride solution as raw material and non - hydrogen reduction solution atomization technology . It was found that high purity nitrogen was suitable as the effective reducing agent in the preparation process . and 5 , carrying out solution atomization to prepare a powder catalyst experiment , preparing a solution according to the stoichiometric ratio , controlling the reaction conditions , and respectively and successfully preparing the alloy powder catalyst comprising Ni7Co3 , Fe7Ni3 , FeNi3 and Ni70Mn25Co5 by adopting a solution atomization method ; Six , the process of preparing NiO and Co304 powder by solution atomization is the object , and the process dynamics research is carried out . It is found that the preparation process consists of three successive steps , namely solute crystallization precipitation , solute dehydration and decomposition , and crystal growth of the product .

【学位授予单位】：中南大学
【学位级别】：博士
【学位授予年份】：2010
【分类号】：TB383.3

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