Catalysis under ultrasonic irradiation: a sound synergy

Through selected examples, we report here that ultrasound is capable of assisting a solid catalyst in various reactions. Beside improvement of heat and mass transfer induced by the implosion of cavitation bubbles, we show that a synergistic effect can occur between catalysis and ultrasound. In particular, the physical and chemical effects locally exerted on a catalytic surface upon implosion of cavitation bubbles can oxidize metal ions, provide energy to the catalyst/reaction, in situ activate or create catalytic sites, and even prevent the catalyst from deactivation. The impact of ultrasound on solid catalyst structures, which may positively or negatively impact the performances of catalysts, is also discussed.