The formation of vanadium pentoxide (V₂O₅) nanoparticles immobilized on alumina (Al₂O₃) particles was studied in a methane/oxygen coflow diffusion-flame reactor. V₂O₅ nanoparticles formed by the decomposition of vanadium oxytriethoxide were deposited onto Al₂O₃ particles, which were introduced into the flame together with vanadium oxytriethoxide solution. To immobilize the V₂O₅ nanoparticles on Al₂O₃ particles, rapid cooling with a Laval nozzle was applied to the V₂O₅/Al₂O₃ particles formed in the flame. We found that it was possible to suppress the sintering of V₂O₅ nanoparticles on the Al₂O₃ particles when the Al₂O₃ particles were introduced into the flame at a temperature sufficiently high to soften the surfaces of the Al₂O₃ particles
