关键词: 反应工程, 混合, 纳米材料, 超重力, 撞击流, 膜包覆

Abstract:

In order to realize continuously and rapidly prepare core-shell structured nanoparticles, a high-frequency impinging stream (HFIS) reactor is explored on the basis of the secondary rotation principle. In this reactor, not only the homogeneous nucleation and heterogeneous nucleation are coupled together, but the liquid-liquid multi-scale mixings are greatly intensified. And then, well-defined nano Fe₃O₄/MnOOH composites were fleetly obtained. The influences of four parameters on the macro and intrinsic kinetics of the coating process were investigated and discussed. Experimental results revealed that low coating ratio prolonged the induction period. Higher initial flux of the main stream intensified the initial dispersion, meso-mixing and micro-mixing. With the total flux of the branch streams being lowered, the initial dispersion was bad off. Furthermore, the computational fluid dynamics (CFD) simulations indicated that the inner layer of the S-shaped main stream had lower pressure and higher flow rate distributions. Therefore, the impinging points should be located in there. Two design defects of the reactor were found, and the corresponding improved schemes were proposed. Through continuous improvement, this reactor is promisingly used for the large-scaled, low-cost and high-quality production of various core-shell nanomaterials.

Key words: reaction engineering, mixing, nanomaterials, high gravity, impinging stream, film-coating