ETHYLENE CONVERSION IN A BARRIER DISCHARGE: EXPERIMENT AND MODELING

The selective conversion of ethylene and its mixtures with argon and air in a barrier discharge has been studied. Plasma chemical transformation proceeds without the formation of polymer-like substances or products of deep oxidation to oxygen-containing compounds and various saturated and unsaturated hydrocarbons. Synthesis is carried out on a set-up with a gas-liquid reactor in the presence of water, which ensures the elimination of formed substances from the discharge area and prevents repeated exposure to barrier discharge plasma. The treatment of ethylene in a barrier discharge leads to the formation of saturated and unsaturated hydrocarbons C-1-C5+ with a predominance of compounds with four carbon atoms in the molecule, the total content of which in the reaction products reaches 58.4 wt.%. The addition of argon to ethylene does not significantly affect the set and content of substances in the reaction products, an increase in ethylene conversion is observed, the maximum value of which reaches 58.9 wt.%. The treatment of a mixture of ethylene with air additives leads to the formation of hydroxyl and carboxyl compounds with a total content of similar to 29 wt.% in the products, and saturated and unsaturated hydrocarbons C-1-C-4 with a predominant acetylene content up to similar to 47 wt.%. The conversion of ethylene in one pass of the reaction mixture through the reactor under these conditions is 12.8 wt.%. When evaluating the energy losses of barrier discharge electrons in electron-molecular interactions during the conversion of ethylene, it was found that 78% of the energy of barrier discharge electrons is spent mainly on excitation of the electronic states of ethylene molecules, and argon additives can increase it to 86%. In the case of conversion of ethylene mixtures with air additives, it is shown that only similar to 14% of the discharge energy is spent on the excitation of the electronic states of the ethylene molecule, and the main amount (65%) is spent on the excitation of various different states of nitrogen molecules. The data obtained were used to develop a model of the chemical kinetics of ethylene conversion in a barrier discharge. The proposed model contains more than 280 reactions and is in good agreement with experimental data. As a result of the simulation, new data were obtained on the behavior of an ethylene molecule in a barrier discharge plasma with an average electron energy of 4-5 eV. The results obtained will be useful in the development of modern ethylene processing methods focused on the technological simplicity and compactness of the chemical process that meets the principles of "green chemistry" and low carbon footprint in the environment.