The effect of mixing on Co-precipitation and evolution of microstructure of Cu-ZnO catalyst

The influence of feeding point in conventional stirred tank reactor and flow characteristics in micro-reactor on the microstructure of Cu-ZnO catalyst was studied. Cu-Zn distribution in co-precipitate was characterized by EDS and Zn fraction in zincian malachite was estimated from the 20 1 peak shift in XRD pattern. The theory analysis and experimental results, combining with measurement of segregation index, show that the contact pattern and mixing of reactants in precipitation process determine the uniformity of Cu-Zn distribution in initial co-precipitates at the micro-scale. The uniform Cu-Zn distribution is favorable for the formation of zincian malachite with higher Zn fraction, whereas the uneven distribution could lead to either zincian malachite with lower Zn fraction or aurichalcite-like nonmalachite. These differences in the precursor structure act on subsequent calcination and reduction, as well as their products. Along this path, mixing affects the evolution of the catalyst microstructure by means of Cu-Zn distribution. (c) 2018 American Institute of Chemical Engineers AIChE J, 64: 2647-2654, 2018