Obtaining of gaseous hydrogen and silver nanoparticles by decomposition of hydrocarbons in ultrasonically stimulated low-temperature plasma

Abstract

In this work, experimental studies of the process of obtaining hydrogen and silver nanoparticles using intense ultrasonic cavitation affecting a plasma discharge in liquid hydrocarbons were carried out.It was shown that ultrasonic action above the cavitation threshold intensifies heat and mass transfer processes in the treated medium, and in combination with an electric discharge, which contributes to the appearance of an ionized state of matter (plasma), such action is capable of decomposing complex hydrocarbon molecules to an atomic state with subsequent recombination and formation simple molecules.Experiments on the production of hydrogen and nanoparticles were carried out on a special installation for the implementation of an acoustoplasmic discharge in a liquid. The installation includes an ultrasonic generator, a piezoceramic transducer, a plasma discharge power source, a reaction chamber, and discharge electrodes.The results of the analysis of gaseous reaction products by gas chromatography show that during the acoustoplasmic decomposition of hydrocarbons, the formation of almost pure hydrogen (90–95%); the composition of the released gas also includes pairs of initial hydrocarbons.Simultaneously with the production of a hydrogen-containing gas, the decomposition of hydrocarbons in a plasma discharge under the action of ultrasonic cavitation results in the formation of silver nanoparticles. The synthesized nanoparticles were isolated and studied using the method of transmission electron microscopy to determine the shape and size of the nanoparticles.The study of the nanoparticles by electron microscopy showed that during the synthesis, particles are obtained, mainly spherical in shape. The size of the synthesized nanoparticles is 30–40 nm. It was also shown by electron microscopy that, upon aggregation, the particles do not become larger in size, but form compound associates. It is also important to note that the advantage of this method for the synthesis of nanoparticles is their activated surface, which has a high reactivity as a result of exposure to intense ultrasound.The resulting nanoparticles and their agglomerates can also be used as functional materials, fillers, and components of composite materials.