定-转子反应器中微乳液-气相法制备催化剂纳米载体的研究

Nano-catalytic materials are the forefront in the development of catalytic materials. Preparation of nano-catalytic materials by microemulsion demonstrates the merits of small particle size and mild process. But stirring is employed as a mixing means in conventional microemulsion method and exhibits poor mixing and mass transfer effects, and it is thus difficult to control the quality of as-prepared product. To address this problem, this project proposes the study on the preparation of nano-carrier of catalysts by microemulsion-gas phase method in a rotor-stator reactor (RSR) by taking advantage of the highly intensified multi-phase mass transfer and micromixing in the RSR. The reaction kinetics equation and mass transfer model of metal alkoxides/n-hexane/（Synperonic? 10/6）/ H2O microemulsion-NH3 system will be established by investigating the absorptive reaction mechanism, fluid mechanics characteristics and mass transfer behavior of the system, so as to formulate a theory for the preparation of CexZr1-xO2 nano-carrier by microemulsion-gas phase method in the RSR. This study will also explore the influence of various factors on the preparation of CexZr1-xO2 nano-carrier by the absorption of NH3 into the microemulsion in the RSR and identify the optimum process conditions, with an attempt of providing a novel process for the controllable preparation of nano-carrier of catalysts and laying the theoretical foundation of industrial application of the process.

纳米催化材料是催化材料发展的前沿和热点。微乳液法制备纳米催化材料具有粒径小、工艺温和等优点，但传统的微乳液法中使用搅拌作为混合手段，混合和传质效果较差，使所制备产品的质量难于控制。有鉴于此，本项目利用新型定-转子反应器（RSR）高度强化多相传质和微观混合的特点，首次提出RSR中微乳液-气相法制备催化剂纳米载体的研究。通过对RSR中金属醇盐/正己烷/（Synperonic? 10/6）/水微乳液- NH3体系的吸收反应机理、流体力学特性和传质规律的研究，建立RSR中该体系的反应动力学方程和传质模型，为RSR中微乳液-气相法制备CexZr1-xO2纳米载体提供理论支持，并探索RSR中微乳液体系吸收NH3制备CexZr1-xO2纳米载体的影响规律和最优工艺条件，为催化剂纳米载体的可控制备提供一条新颖的技术路线并奠定其工业推广的理论基础。

定-转子反应器（Rotor-stator Reactor, RSR）是一种建立在旋转填充床（Rotating Packed Bed, RPB）基础上的新型超重力设备，它主要由在径向上交错排布的同心转子环和定子环构成。液体在RSR中高速旋转的转子及静止的定子作用下，被剪切破碎，形成微小的液膜或者液滴，使得气液两相湍动程度及气液两相界面更新速率大大增加，使传质及微观混合过程得以高度强化，因此，RSR在传质控制的化工过程中展现出很强的应用前景。.本项目研究针对RSR这一新型反应器，进行了流体流动及气液间传质过程等基础研究，并针对微乳液/乳液黏度高、浓度分布不均匀的特点，利用RSR强化传质与混合过程，形成一种RSR中微乳液-气相法制备纳米催化材料的新技术。主要成果如下：.1、通过可视化研究结果显示，在实验条件下RSR内水液滴平均直径在311-1045 μm之间，平均速率在1.73-8.86 m∙s-1之间；微乳液液滴平均直径在271-775μm之间，平均速率在2.08-7.34 m∙s-1之间。.2、利用NH3-水体系对RSR内气相总体积传质系数（Kya）进行了研究，实验结果显示，所用实验条件下RSR内Kya在47.3-97.5 mol∙m-3∙s-1之间。.3、利用NH3-油包水型（W/O）微乳液体系对RSR内Kya进行了研究，实验结果显示，在实验条件下RSR内Kya在19.5-73.0 mol∙m-3∙s-1之间。.4，在RSR中制备了平均粒径为5.5 nm，粒径分布为4-8 nm，比表面积为215.6 m2∙g-1的纳米Ce0.5Zr0.5O2载体。利用所得载体负载贵金属得到的Au/Ce0.5Zr0.5O2催化剂在室温（25 ℃）下即可将CO完全催化转化。