Microwave-assisted continuous flow synthesis on industrial scale

Abstract

A continuous fl ow microwave system based on a transmission line short-circuited waveguide reactor concept is described. The continuous fl ow reactor is capable of operating in a genuine high-temperature/high-pressure process window (310 ° C/60 bar), applying a microwave transparent and chemical resistant cylindrical γ -Al 2 O 3 tube as reaction zone. The system can be operated in an extremely energy effi cient manner, utilizing 0.6 -6 kW microwave power (2.45 GHz). The application of the reactor for processing four chemical transformations in a high-temperature/high-pressure regime with a throughout of 3.5 -6.0 l/h is demonstrated.

Chemical reaction engineering, process design and scale-up issues at the frontier of synthesis: Flow chemistry

“…The advantages and disadvantages of the different AM techniques have been effectively compared by Capel et al [123] as synthesized in Table 2. MW and ultrasound (US) assisted synthesis in continuous flow have been also proposed in the biorefinery field up to the pilot and industrial scale [127,129].…”

“…For instance, the synthesis of benzimidazole was accomplished at 270°C, 30-50 bar with extremely short residence time and accordingly scaled [129]. However, the use of high temperatures may lead to safety issues if instable intermediates are involved, such as the case of azides, which rapidly decompose forming nitrogen.…”

Energy consumption estimation in the scaling-up of microwave heating processes

“…However, as will be demonstrated in this paper, to draw conclusions about the viability of a process based on results obtained at such a low scale can be risky and, depending on the amounts of sample used in the experiments, sometimes meaningless. Moreover, nowadays most research efforts in this field are focused on the scaling-up of microwave processes and the first encouraging results are appearing [12,13,18,19]. For these reasons it is important to determine how the energy consumption of microwave-heated processes varies depending on the scale used.…”

Microwave-Assisted Facile and Rapid Esterification of Amino Acids I: Esterification of L-Leucine from Batch to Flow Processes and Scale-Up

“…Indeed, a number of reports have been published discussing the application of microwave irradiation in organic synthesis for accelerating reaction rates and improving product selectivity. However, to date, the majority of studies on microwave-assisted synthesis have been carried out using desktop-scale reactors, despite various reports on the scale-up of microwave syntheses for potential application on an industrial scale [8][9][10][11].…”