Processing of oil products using complex radiation-thermal treatment and radiation oxonolysis

Most of industrial radiation facilities afford an opportunity to produce a considerable amount of reactive ozone-containing gaseous mixtures parallel to the basic production that causes no detriment to the output of the main designed product. The synergetic action of the ozone-containing mixtures and ionizing radiation is of a special interest for industrial application since it can be efficiently used in a wide range of technologies, in particular, for stimulation of chemical conversion in hydrocarbons accompanied by intensive oxidizing processes. In this paper the effect of simultaneous radiation-thermal processing and radiation oxonolysis on hydrocarbon chemical conversion, and subsequent alterations in composition and properties of oil products were studied on the example of high-viscous oil (Karazhanbas field, Kazakhstan) subjected to irradiation by 2 MeV electrons combined with radiation ozonization in the bubbling mode. It was stated that application of the bubbling mode for radiation-induced ozonization of high-viscous oil leads to decrease in the yields of engine fuels in average by 8-10 % compared with those obtained in the conditions when radiation-thermal cracking was applied without bubbling. In the latter case mean yields of the wide gas-oil fraction with boiling start temperature of 350 deg. C, that included gasoline, kerosene, and diesel fuel, were about 76-80 %. Decrease in the gasoline yields does not lead to noticeable alterations in hydrocarbon contents of the gasoline fraction (boiling beginning bellow 175 deg. C) compared with gasoline produced be radiation-thermal cracking, in both cases it meets requirements for high quality standards. However, essential difference was observed in properties of heavy residua of oil processing (oil fractions with Tboil>350 deg. C), i.e. the fractions that contained high concentrations of asphaltenes and pitches. Application of radiation oxonolysis diminishes concentrations of high-molecular aromatic compound due to disintegration of condensed polyarene nuclei included in molecules of pitches and asphaltenes. It also leads to considerable decrease in the mean molecular mass of the residue, elimination of the part of sulfur and nitrogen atoms, and enrichment of the heavy residue by oxygen. At the same time the degree of hydrogen deficiency becomes lower due to the opening of the part of aromatic rings. Splitting of pyrrol and thiophene cycles diminishes sulfur contents and simultaneously causes a rise in oxygen concentration. Data of infra-red spectroscopy confirm that radiation oxonolysis in the bubbling mode causes disintegration of aromatic nuclei and oxidation of sulfuric compounds. The results obtained open new opportunities for upgrading high-viscous oils and raising their potential fuel yields due to higher commercial validity of heavy residue after combined radiation-thermal processing and oxonolysis