OXIDATION OF PROPANE-BUTANE MIXTURE IN DIELECTRIC BARRIER DISCHARGE IN PRESENCE OF LIQUID OCTANE

Abstract

The results of oxidation of a propane-butane mixture in a barrier discharge plasma in the presence of liquid octane are presented. The conversion of the gas-liquid mixture results in the formation of an oxygenate containing predominantly hydroxyl and carbonyl compounds with the same number of carbon atoms in a molecule as in the starting compounds. The presence of a liquid octane film flowing down the plasma-chemical reactor walls enables an effective removal of the reaction products from the discharge zone due to dissolution of the compounds formed therein. Alkyl radicals, atomic oxygen, and hydrogen are the main active particles. The formation of both oxygenated compounds and hydrocarbons with isomeric structure occurs as a result of their further chemical transformations. The mechanism of conversion of gaseous hydrocarbons is much like that for the conversion of liquid hydrocarbons in a barrier discharge plasma. They both are carried out under similar conditions. The change in the initial concentration of the propane-butane mixture in the gas phase from 10 to 75 % wt results in a decrease in the conversion of gaseous hydrocarbons from 4.1 to 0.9 % wt, while the conversion of octane decreases from 2.4 to 0.3% wt. in one pass through the reactor. The decrease in hydrocarbon conversion is due to decrease in the rate of formation of atomic oxygen in a discharge gap of the reactor. Theoretical calculations were performed using the software package Bolsig+ for the model oxygen-propane mixture. The results of calculations show that the rate constant of oxygen dissociation increases from 1.87·10-10 cm3/s to 6.71·10-9 cm3/s, due to an increase in the average electron energy from 3.4 to 4.1 eV. It was found out that the mass of products formed in result of oxidation of gaseous and liquid hydrocarbons depends on the initial concentration of the starting compounds in the vapor-gas mixture. A simple expression is proposed that allows one to evaluate the preferential direction of the plasma-chemical reaction as a function of the initial concentration of hydrocarbons in a discharge gap of the reactor.Forcitation:Kudryashov S.V., Ryabov A.Yu., Ocheredko A.N. Oxidation of propane-butane mixture in dielectric barrier discharge in presence of liquid octane. Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol. 2018. V. 61. N 3. P. 88-92