The importance of agitation and fill volume in small scale scientific microwave reactors

Synthesis of Biodiesel through Catalytic Transesterification of Various Feedstocks using Fast Solvothermal Technology: A Critical Review

“…To overcome this issue, some innovative scientists have taken special efforts to modify a household microwave oven (HMO) properly which could be more useful as laboratory equipment with incomparable costs. Based on reports, up to 30% of experiments are currently being conducting by using modified domestic microwave oven (DMO) irradiation (90). On the other hand, the utilizing DMO on a laboratory scale results in the eruption or explosion of vessels because of being unable to control the heating of the solvents under a sealed container system.…”

Microwaves in Heterogeneous Gas‐Phase Catalysis: Experimental and Numerical Approaches

“…However, using FO requires that particular attention be paid to sensor positioning during experiments, to avoid damaging of the probe and to ensure reproducible results. Although there is general agreement that the application of FO for temperature measurement under microwave irradiation is one of the best techniques [82][83][84], Bogdal et al [83] proved that in viscous homogeneous reaction media or in heterogeneous solid samples the temperature obtained by FO is only a "local" temperature -different from the average bulk temperature.…”

Microwave Theory

“…In general, external IR sensors will only represent the internal reaction temperature properly if efficient agitation of the homogeneous reaction mixture is ensured. Inefficient agitation can lead to temperature gradients within the reaction mixture due to field inhomogeneities in the highdensity single-mode microwave cavities [23,25,26]. Extreme care must therefore be taken with heterogeneous reactions, such as solvent free, dry-media or highly viscous systems (see Section 4.1).…”

“…Taking into account inherent field inhomogeneities that exist in both cavities [23], this fact in itself can lead to discrepancies when comparing the results obtained from running the exact same chemical reaction in the two systems [26]. It has to be noted that in the Biotage microwave systems a certain minimum filling volume must be used in order to ensure a proper temperature reading (see Section 5.3.3).…”