We present a flow type single-mode microwave (MW) reactor that forms a uniform electromagnetic field along a tubular reactor (quartz glass, i.d. 1.5 mm × 100 mm) located in the center of a cylindrical MW cavity. The temperature of liquid flow in the reactor tube was controlled precisely by a resonance frequency autotracking function. This MW reactor system is useful for rapid heating of liquid flow at pressures up to 10 MPa. Continuous flows of polar solvents including water, ethylene glycol, and ethanol were heated instantaneously beyond their boiling points by application of pressure. Acceleration of the reaction was exemplified in continuous synthesis of Cu nanoparticles by elevation of the reaction temperature beyond the boiling point of solvent (ethylene glycol) at 2 MPa.

Rapid and continuous synthesis of size-controlled platinum nanoparticles is achieved using a single-mode microwave flow reactor controlled with temperature feedback module. Platinum nanoparticles are synthesized within 2.8 s of residence time in glycerol and 1,3-propanediol having large dielectric dissipation factor and high solvent viscosity.