Microwaves selectively heat solid catalysts and allow enhancement of fixed-bed flow reactions. In this study, microwave
in situ and
operando Raman spectroscopy and resonance frequency were performed for real-time monitoring of the oxidation state of the tungsten oxide (WO
3) catalyst during microwave irradiation. First, the enhancement of catalytic dehydration and dehydrogenation over WO
3 catalyst was demonstrated under microwave irradiation.
Operando Raman spectroscopy revealed that the remarkable reduction occurred at the surface of the WO
3 catalyst. We further applied
in situ resonance frequency for real-time monitoring of oxidation state of WO
x during model oxidation reaction of WO
2 to WO
3. We found that the oxidation state of WO
x determined by the
in situ resonance frequency was comparable to that obtained by XRD. However, the changes in the resonance frequency should be considered carefully because it is also affected by the volume and temperature of the samples.
View full abstract