Continuous flow-microwave reactor: Where are we?

Abstract

This article presents the different microwave continuous reactors existing, which are reported in literature to carry out chemical synthesis with a more efficient way. It shows how the methods and tools of chemical engineering can be useful and necessary to define, characterize and optimize the microwave reactors. This review scans continuous microwave reactors, by describing the different types of microwave technologies used (multimode, single-mode, coaxial or guided transmission. . .). It then focuses on the various existing reactor geometries and on the control of the electromagnetic field homogeneity. The problem of temperature measurement and overall instrumentation is also addressed (input power, reflected power, continuous adaptation. . .). This review scans the most efficient microwave continuous flow reactors existing in the literature and highlights how the microwave technology is used as well as chemical engineering tools. It points out the reactors geometries, the control of the electromagnetic field and the measurement of the physical parameters (Temperature, microwave power, etc.). Finally, the scale-up of continuous-flow microwave reactors is examined through the existing lab-scale and semi industrial pilot plants described in literature.

Microwave Intensified Synthesis: Batch and Flow Chemistry

“…In addition to excellent control of reaction temperature, the latest microwave-assisted methods reportedly possess such advantages as rapid heating, increased reaction rate and excellent reproducibility, resulting in high energy efficiency, narrow particle distribution, high purity and high yields. [3,4,[14][15][16]…”

Rapid Optimization of Reaction Conditions Based on Comprehensive Reaction Analysis Using a Continuous Flow Microwave Reactor

“…Although the penetration depth of the microwave is a drawback, [19] the problem can be solved by combining it with the flow method. [20] We utilized a microwave flow system (see 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 frontispiece) that can monitor and control the reaction conditions and verify the optimization of basic and practical organic reactions.…”

Microwave‐induced polar/nonpolar mixture separation performance in a film evaporation process

“…In addition, a temperature gradient does not exist inside the material since the heat energy is simultaneously internally generated throughout the material. When microwave irradiation is applied to materials, it can produce electron polarization, atomic polarization, and interfacial and dipole orientation polarization, and the latter two are the main dielectric heating mechanisms. Since molecular motion is caused by ion migration or dipole molecule rotation, microwave heating largely depends on the dissipation factor or dielectric loss tangent, tan δ , which indicates the magnitude of the microwave energy lost in the form of heat dissipation into the material where ε ′ is the relative dielectric constant, which describes the ability of a material to store electrical energy; and ε ″ is the dielectric loss factor, which indicates the ability and efficiency of the microwave energy absorbed by the material to be converted into heat.…”