We present a helicopter view of microwave technology application to various reaction and separation processes, including liquid-phase organic syntheses, gas-solid catalytic reactions, polymerizations, extraction, distillation, crystallization, membrane separation, and adsorbent regeneration/dehydration. The overarching aim is to demonstrate the breadth of potential applications of microwave technology to chemical industry, with particular attention to separations, as this is a less explored microwave application area. In this context, some key findings, opinions, and developments in the relevant literature are summarized. In addition, the present microwave equipment concepts for chemical processes are critically reviewed and new ones are put forward, as we believe that an important milestone in the road from laboratory-scale microwave experimentation to industrial-scale microwave-assisted chemical processing is the design and development of innovative microwave equipment concepts tailored for specific chemical processes.
The
complexity and challenges in noncontact temperature measurements
inside microwave-heated catalytic reactors are presented in this paper.
A custom-designed microwave cavity has been used to focus the microwave
field on the catalyst and enable monitoring of the temperature field
in 2D. A methodology to study the temperature distribution in the
catalytic bed by using a thermal camera in combination with a thermocouple
for a heterogeneous catalytic reaction (methane dry reforming) under
microwave heating has been demonstrated. The effects of various variables
that affect the accuracy of temperature recordings are discussed in
detail. The necessity of having at least one contact sensor, such
as a thermocouple, or some other microwave transparent sensor, is
recommended to keep track of the temperature changes occurring in
the catalytic bed during the reaction under microwave heating.
We investigate the existence of specific/nonthermal microwave effects for the dehydration reaction of xylose to furfural in the presence of NaCl. Such effects are reported for sugars dehydration reactions in several literature reports. To this end, we adopted three approaches that compare microwave‐assisted experiments with a) conventional heating experiments from the literature; b) simulated conventional heating experiments using microwave‐irradiated silicon carbide (SiC) vials; and at c) different power levels but the same temperature by using forced cooling. No significant differences in the reaction kinetics are observed using any of these methods. However, microwave heating still proves advantageous as it requires 30 % less forward power compared to conventional heating (SiC vial) to achieve the same furfural yield at a laboratory scale.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.