太原理工大学 硕士学位论文 反应物粒度对固液反应动力学的影响及其影响机理的研究 姓名：王肖鹏 申请学位级别：硕士 专业：物理化学 指导教师：薛永强 20100601 太原理工大学硕士研究生学位论文 II 反应物粒度对固液反应动力学的影响 及其影响机理的研究 摘 要 人们很早就发现减小反应物的粒度可以增大反应速率，并将此归因于增大 了反应物之间的接触面积。后来人们逐渐发现，减小反应物粒度不仅可以增大 反应物之间的接触面积，还可以降低反应活化能，甚至还可以改变反应产物及 反应机理。这方面研究较多的是粒度对反应物热分解动力学的影响，而粒度对 固液反应动力学和机理的研究还很少，并且关于粒度对指前因子和速率常数的 影响机理的研究还未见报道。研究不同粒度的纳米颗粒对固液反应动力学的影 响及其影响机理，对物理化学学科的发展具有重要的理论意义，对纳米粒子在 化学领域中的应用具有重要的理论指导作用。 论文首先通过试验筛选出反应速率适中的三个固液反应，分别是纳米氧化 镍与硫酸氢钠的反应、纳米氧化镁与硫酸氢钠的反应和纳米氧化锌与丙烯酸溶 液的反应。 其次， 以六水硝酸镍与尿素为原料， 采用均匀沉淀法制纳米氧化镍前驱体， 通过热重分析确定了最低煅烧温度 400；前驱体经煅烧即可得纳米氧化镍， 采用 XRD 和透射电子显微镜进行分析得：纳米氧化镍晶体为立方晶系，近似 为球型； 通过改变实验条件， 可以制备出不同粒径的纯度为 99%的纳米氧化镍， 其平均粒径为 5.0-30nm；且纳米氧化镍的粒径随反应物配比的增加、随着煅烧 温度的减小及煅烧时间的减小而减小； 纳米氧化镍前躯体的产率随反应物配比 （n尿素/n六水硝酸镍）的增加而增加。 太原理工大学硕士研究生学位论文 III 以六水硝酸锌和尿素为原料通过均匀沉淀法制得纳米氧化锌前驱体， 采用 XRD 和热重分析得前驱体为 Zn5(OH)6(CO3)2，最低煅烧温度 400。前驱体经 煅烧即可得纳米氧化锌；采用 XRD 和透射电子显微镜进行分析得：纳米氧化 锌为六方晶系，近似为球形颗粒；通过不同实验条件可以制备出纯度为 99%的 不同平均粒径的纳米氧化锌，平均粒径为 20-50nm；且纳米氧化锌颗粒的平均 粒径随反应物浓度的减小、反应温度和煅烧温度的降低而减小；纳米氧化锌的 产率随反应物浓度的增大、反应物配比的增大和反应温度的升高而增大。 以氧化镁和碳酸铵为原料，采用均匀沉淀法制备出纳米氧化镁前驱体，经 煅烧得纳米氧化镁。采用XRD分析得：纳米氧化镁为立方晶系，近似为球形颗 粒；通过不同实验条件可以制备出纯度较高的不同平均粒径的纳米氧化镁，平 均粒径为5-37nm；且纳米氧化镁的粒径随反应物浓度的减小，反应温度的升高 和随煅烧温度的减低而减小。 然后，利用离子分析仪，通过测定不同粒径和不同温度下溶液的瞬时pH值 或参与反应的离子浓度，得到不同粒度和不同温度时纳米粒子的反应速率；最 后得出速率常数、反应级数、活化能、指前因子随粒度的变化规律；讨论了粒 度对固液反应动力学参数的影响及其影响机理。 研究结果表明：反应物的粒度对其反应的速率常数、表观活化能和指前因 子均有显著的影响；随着反应物粒径的减小，反应的表观活化能和指前因子减 小而速率常数和反应级数增大；并且速率常数的对数、指前因子的对数和表观 活化能分别与反应物粒径的倒数呈较好的线性关系；反应物粒度对多相反应动 力学参数的影响机理是：纳米反应物的摩尔表面积影响反应级数，其摩尔表面 能影响表观活化能，其摩尔表面熵影响指前因子，摩尔表面能和摩尔表面熵共 太原理工大学硕士研究生学位论文 IV 同影响速率常数。 关键词：纳米；粒度；反应动力学；反应速率；反应级数；指前因子；活化能 太原理工大学硕士研究生学位论文 V THE EFFECT OF REACTANTS PARTICLE SIZES ON THE KINETIC PARAMETERS AND THE AFFECT INTERPRETATION IN SOLID-LIQUID REACTIONS ABSTRACT It has been found that reducing the size of reactants can increase the reaction rate long ago and ascribed that to the increased contact area between reactants. Later, people gradually found that the reduce of reactants size not only can increases the contact area between reactants, but also can reduce the activation energy and can even change the reaction products and reaction mechanism. There are many studies on kinetics of thermal decomposition, while the study about the effect of particle size on the kinetics of solid-liquid reaction is still little and the report about the affect interpretation of particle size on the pre-exponential factor and reaction constant has not been found. Therefore, the investigation of effects of particle sizes on chemical reactions by using nanoparticles as the reactant has important theory meanings for developing physical chemistry and theoretics guidances for applying nanoparticles to chemical fields. Firstly three solids-liquid reactions having moderate reaction rate were screened through experimentation and are reactions of nano-NiO and sodium bisulfate, nano-MgO and sodium bisulfate and nano-ZnO and acrylic acid solution respectively. Then the precursor of nano-NiO was prepared with nickelous nitrate and carbamide by homogeneous precipitation and was analyzed by XRD and TG. The result shows that calcining temperature is 400 at least. The nano-NiO crystalline can obtained by calcinating precursor and were analyzed by XRD and TEM. The results show that nano-NiO crystal is cubic structure, similar to the ball; nano-NiO of 99% purity was prepared under different experimental conditions, and the range of average particle size is 5.0-30nm; and nano-NiO diameter decrease with the increase of the ratio of reactants, with the decrease of calcination temperature and with the decrease calcination time and the yield of the precursor increase with the increase of rate of reactants. 太原理工大学硕士研究生学位论文 VI The precursor of nano-ZnO was prepared with zinc nitrate and carbamide by homogeneous precipitation and was analyzed by XRD and TG. The rusults show that the precursor is Zn5(OH)6(CO3)2 and the calcining temperature is 400 at least. The nano-ZnO crystalline can obtained by calcinating precursor and were analyzed by XRD and TEM. The results show that nano-ZnO crystalline is hexagonal, approximately spherical particles; different average nano-ZnO were prepared by different experimental conditions and the range of average particle size is 20-50nm; and the nano-ZnO diameter decrease with the decrease of the reactant concentration, with the decrease of the reaction temperature and with the decrease of the calcination temperature; nano-ZnO yield increase with the increase of the reactant concentration, with the increase of the reactant ratio and with the increase of the reaction temperature. The precursor of nano-MgO was prepared with magnesia and salvolatile by homogeneous precipitation method. The nano-MgO crystalline can obtained by calcinating precursor and were analyzed by XRD. The results show that nano-MgO is cubic crystal system, approximately spherical particles; different average nano-MgO were prepared by different experimental conditions and the range of average particle size is 5-37nm; and nano-MgO diame