微反应器中的混合对Cu-ZnO催化剂微结构形成过程的影响

摘要

通过对微反应器中流速的调控,研究了混合过程对 Cu-ZnO 催化剂微结构形成过程的影响.采用Villermaux-Dushman反应体系测量了不同流速下反应器中的混合状况,采用X射线衍射(XRD)、高倍电镜线扫(EDS)、X射线光电子能谱(XPS)分析了对应流速下制备得到的前体和氧化物的结构.结果显示,混合强度增加,前体中的 Cu2+、Zn2+分布更为均匀,绿铜锌矿的比例减小,锌孔雀石中的 Zn 含量提高;进而导致其热分解形成的氧化物中 Cu-Zn 分布也更为均匀,CuO-ZnO 界面增加,CuO 晶粒粒径减小.研究表明,沉淀反应时混合条件的改变,导致后续系列中间产物中Cu-Zn分布的差异,通过这一路径,混合对反应的影响最终作用于催化剂结构.%The influence of mixing inside the microreactor on the microstructural evolution of Cu-ZnO catalyst was investigated by regulating the flow rate. Mixing efficiency in the microreactor was measured by Villermaux-Dushman reaction system under different flow rates, and the structures of precursor and oxide were characterized by X-ray powder diffraction (XRD), energy dispersive spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS). The results showed that with increase of the mixing intensity, the distribution of Cu2+and Zn2+ in precursor becomes more uniform, the fraction of aurichalcite decreases and Zn content in zincian malachite rises. The difference in the precursors acts on the oxides, leading to a more uniform Cu-Zn distribution, a better dispersion between CuO and ZnO, and the decrease of CuO size. Above study reveals, it is by the Cu-Zn distribution that the changes of mixing during the precipitation affects the subsequent product and results in the difference in Cu-ZnO catalyst microstructure.