Current Trends in the Development of Microwave Reactors for the Synthesis of Nanomaterials in Laboratories and Industries: A Review

Abstract

Microwave energy has been in use for many applications for more than 50 years, from communication, food processing, and wood drying to chemical reactions and medical therapy. The areas, where microwave technology is applied, include drying, calcination, decomposition, powder synthesis, sintering, and chemical process control. Before the year 2000, microwaves were used to produce ceramics, semiconductors, polymers, and inorganic materials; in next years, some new attempts were made as well. Nowadays, it has been found that microwave sintering can also be applied to sintered powder and ceramics and is more effective than conventional sintering. Particularly interesting is its use for the synthesis of nanomaterials. This review identifies the main sources of microwave generation, the delivery mechanisms of microwave energy, and the typical designs and configurations of microwave devices, as well as the measurement and construction material problems related to microwave technology. We focus our attention on the configurations, materials, optimized geometries, and solvents used for microwave devices, providing examples of products, especially nanoparticles and other nanomaterials. The identified microwave devices are divided into four groups, depending on the scale, the maximum pressure developed, the highest temperature for sintering, or other special multi-functions. The challenges of using microwave energy for the synthesis of nanopowders have been identified as well. The desirable characteristics of microwave reactors in the synthesis of nanostructures, as well as their superiority over conventional synthetic methods, have been presented. We have also provided a review of the commercial and self-designed microwave reactors, digestors, and sintering furnaces for technology for synthesis of nanomaterials and other industries.

Glycerol: An Optimal Hydrogen Source for Microwave-Promoted Cu-Catalyzed Transfer Hydrogenation of Nitrobenzene to Aniline

“…Since late 1960s the development of industrial applications of MW heating was mainly for drying and other thermal treatments. Today MW technology is exploited in several areas: drying (Feng et al, 2012), calcination, decomposition, polymerization (Kempe et al, 2011), chemical process control (Bhusnure et al, 2015), and production of nanomaterials (Dabrowska et al, 2018). In spite of the outstanding achievements in MW-assisted organic synthesis, its industrialization is limited to few applications.…”

Continuous Flow Esterification of a H-Phosphinic Acid, and Transesterification of H-Phosphinates and H-Phosphonates under Microwave Conditions

“…Due to the dynamical development in the field, up-to-date models of MW reactors have appeared on the market. The application of the MW technique embraces above all organic chemical syntheses, the preparation of nanomaterials, and broadly understood material processing [4][5][6]. The most suitable reactions for MW assistance include multicomponent reactions, condensations, eliminations, and substitutions as exemplified by esterifications, C-C cross couplings, dehydrations and the Mannich condensation [7].…”

Noise Suppression and Precise Phase Control of a Commercial S-Band Magnetron

“…[2,14] Because of such competitiveness, magnetrons have been widely adapted in various fields such as microwave ovens of home appliances, radars, communication, medical accelerators, generation of processing plasmas, industrial heating and chemical process intensification. [15][16][17][18][19] In addition, capital cost of a magnetron is superior compared to other high-power microwave modules. [20] Magnetron devices, however, are vulnerable to harmonic and frequent spiky noise compared to other microwave modules, resulting in the instability of the phase and the frequency.…”