Formation of formaldehyde under the effect of ultrasonic radiation on aqueous solutions of light hydrocarbons.

One of the modern and rapidly developing methods of intensifying chemical and physical processes is the use of ultrasonic action on reacting systems. In this study, the transformation of methane, ethylene and their mixtures in aqueous solutions under the influence of ultrasonic radiation with a frequency of 22 and 44 kHz under cavitation conditions was investigated. The experiments were carried out under both static and flow conditions. It has been established that formaldehyde, which is the main product, is formed even if there is no dissolved molecular oxygen in the initial solution. It has been shown that with an increase in the power of ultrasonic radiation, and the amount of molecular oxygen introduced into the system the rate of accumulation of formaldehyde increases. All other things being equal, the rate of accumulation of formaldehyde at an ultrasound frequency of 22 kHz is always higher than at 44 kHz. It is assumed that chemical processes in the studied systems can be a consequence of both radical reactions and the ionization of gases under the influence of ultrasonic radiation. The probable mechanism of formaldehyde formation in an aqueous solution of ethylene was analyzed using quantum-chemical calculations.