Effect of water layer on Cu-Zn co-precipitation in microreactor

CHEN Xinchao1 LING Chen1 JIANG Xin1 CHEN Shuaishuai1 LU Jiangang2

(1.Zhejiang Provincial Key Laboratory of Advanced Chemical Engineering Manufacture Technology, College of Chemical and Biological Engineering, Zhejiang University, Hangzhou, Zhejiang, China 310027)
(2.State Key Laboratory of Industrial Control Technology, Department of Control Science and Engineering, Zhejiang University, Hangzhou, Zhejiang, China 310027)

【Abstract】A method aiming to prepare more uniform Cu-Zn co-precipitate by coupling of diffusion and reaction process was probed in this article and Cu/ZnO co-precipitated catalysts with high catalytic activity were prepared by introducing water layer into the microreactor and adjusting the ratio of water layer to the total flow. The microstructures and evolution process of the catalysts were analyzed by HRTEM/EDS, X-ray diffraction (XRD), thermogravimetric analysis (TG), hydrogen temperature-programmed reduction (H2-TPR), and N2O chemical reaction methods. The results show that as the proportion of water layer increases, the Cu-Zn distribution of the initial precipitate is more uniform; zinc content in the precursor obtained by the aging is increased; the contact area of the oxides CuO and ZnO is increased; and the interaction force is continuously enhanced. Therefore, larger contact area between calcined oxides CuO and ZnO was achieved, leading to better dispersibility and stronger interaction, with the final catalytic activity of the catalyst significantly enhanced. Numerical analysis based on the model established by MATLAB revealed that the uniformity caused by slower reaction rate of Zn2+ can be neutralized by faster diffusion rate of its own. The diffusion–reaction equilibrium region, defined as capable to obtain uniform precipitate, was enlarged with the increasing ratio of water layer and larger proportion of uniform precipitate was achieved simultaneously.

【Keywords】 microreactor; co-precipitation; microstructure; model; numerical simulation; Cu-Zn distribution; diffusion–reaction equilibrium;

【DOI】

【Funds】 National Key Research and Development Program of China (2017YFC0211802) National Natural Science Foundation of China (21276223, 21676236)

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(Translated by WANG YX)

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This Article

ISSN:0438-1157

CN: 11-1946/TQ

Vol 69, No. 10, Pages 4261-4268

October 2018

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Article Outline

Abstract

  • Introduction
  • 1 Experimental materials and methods
  • 2 Results and discussion
  • 3 Conclusions
  • References