Micromixing and Co-Precipitation in Continuous Microreactors with Swirled Flows and Microreactors with Impinging Swirled Flows

Abstract

One of the promising methods for process intensification for micromixing, co-precipitation, and crystallization in continuous reactors is the use of vigorous vortices. A combination of the high intensity of the kinetic energy input with the small volume of the micromixing volume allows to concentrate the energy dissipation rate up to 104 W/kg and more. As the embodiment of such an idea, four new types of microreactors with intensively swirled flows were created and studied as a tool for continuous co-precipitation and crystallization. A correlation between residence time and segregation index was found: the smaller residence time, the higher energy dissipation rate and better quality of micromixing. A method for the synthesis of oxides of a number of transition metals in microreactors with intensively swirled flows with subsequent thermal treatment of co-precipitation products has been developed. This method was used to obtain ensembles of nanosized particles of zirconium oxides, as well as calcium and strontium fluorides. In comparison with the currently widely used hydro- and solvothermal methods, the proposed method has high productivity (around 10 m3/day for lab scale device), can significantly reduce the duration of the process, provides low energy consumption, does not require a large number of labor-intensive operations, is technologically advanced and easily scalable.

Synthesis of strontium fluoride nanoparticles in a microreactor with intensely swirling flows

“…The design of the microreactor with impinging swirling flows is described in [72]. The reactor from pyrex glass has two tangentially arranged nozzles for the supply of the initial components and a nozzle for the discharge of products.…”

“…At the same time, the organization of such conditions that allow the reagents to be distributed at the molecular or ionic level with the necessary degree of uniformity of their distribution in micro-volumes is an obvious prerequisite for obtaining nanoparticles with specified characteristics. Previously, the possibility of synthesis of nanoscale particles of oxides and fluorides in microreactors with impinging jets [67][68][69][70] and in microreactors with intensely swirling flows [67,[71][72][73][74] was experimentally proved. The influence of specific energy dissipation rate on micromixing quality was demonstrated experimentally by means of iodide-iodate method widely used for microreactors with ultimate level of micromixing [74].…”

Y-tube assisted coprecipitation synthesis of iron-based Prussian blue analogues cathode materials for sodium-ion batteries

“…Through the coupling of micro-mixing and reaction processes, the micro-mixing rate is synchronized with the reaction rate, ultimately yielding products with fewer vacancy defects and crystal water. [50][51][52] In traditional stirred-tank reactors, the micro-mixing efficiency is low, leading to material concentration gradients within the vessel, resulting in uneven saturation distribution. Micro-mixing times are oen prolonged, leading to varying micro-mixing conditions in different regions.…”