Conversion of ammonia to hydrazine induced by high frequency ultrasound

Anaelle Humblot (1) , Laurie Grimaud (1) , Audrey Allavena (1) , Prince Nana Amaniampong (1) , Karine de Oliveira Vigier (1) , Tony Chave (2) , Stéphane Streiff (3) , François Jerome (1)

1 IC2MP [Poitiers] - Institut de chimie des milieux et matériaux de Poitiers [UMR 7285]
2 LSFC - Sonochimie dans les Fluides Complexes
3 E2P2L - Eco-Efficient Products & Processes Laboratory

Hydrazine is a chemical of outmost importance in our society, either for organic synthesis or energy purpose. The direct conversion of NH3 to hydrazine is highly appealing but it remains a very difficult task because the degradation of hydrazine is thermodynamically more feasible than the cleavage of the N-H bond of NH3. As a result, any catalyst capable of activating NH3 will thus unavoidably decompose N2H4. Here we show that cavitation bubbles, created by ultrasonic irradiation of aqueous NH3 at a high frequency, act as micro-reactors to activate and convert NH3 to NH species, without assistance of any catalyst, yielding hydrazine at the bubble-liquid interface. The compartmentation of in situ produced hydrazine in the bulk solution, which is maintained close to 30°C, advantageously prevents its thermal degradation, a recurrent problem faced by previous technologies. This work also points towards a path to scavenge •OH radicals by adjusting the NH3 concentration.

Domaines: Chimie

Anaelle Humblot, Laurie Grimaud, Audrey Allavena, Prince Nana Amaniampong, Karine de Oliveira Vigier, et al.. Conversion of ammonia to hydrazine induced by high frequency ultrasound. Angewandte Chemie International Edition, 2021, ⟨10.1002/anie.202109516⟩. ⟨hal-03365866⟩