Determining the influence of microwave-induced thermal unevenness on vanadium oxide catalyst particles

•Thermal unevenness of V2O5 catalyst due to microwaves was analyzed by thermography.•Local heat generation started from the contact point of spherical V2O5 particles.•Thermal distribution dynamically changed depending on the oxidation state of V2O5.•Raman spectra demonstrated the enhanced V2O5 redox by microwaves.•Local hot spot and catalyst oxidation state synergistically accelerate catalytic reaction. Microwave (MW) heating accelerates various heterogeneous catalytic reactions at low temperatures, leading to energy-efficient catalytic processes. Herein we report the formation of MW–formed uneven thermal distribution at the interparticle of V2O5 catalyst by using microscopic thermography and electromagnetic/thermal flow simulations. The local heat generation started from the contact point of the spherical catalyst particles. The uneven thermal distribution changed as the oxidation state of the catalyst dynamically changed during the dehydration of 2-propanol. In situ Raman spectroscopy suggested that dynamic change in the thermal gradient attributes to the oxidation state of the V2O5 catalyst. As a result, the formation of the local hot spot at the contact point of the V2O5 catalyst particles, as well as the oxidation state of V2O5 due to MWs, synergistically affect the enhancement in the dehydration of 2-propanol. The present results provide important insights into a mechanistic understanding of the reaction enhancement of the fixed-bed flow reaction owing to the MW-induced uneven thermal distribution.