渣油超临界萃取馏分中硫化物的分离富集研究

In order to reduce the sulfur content of the liquid transportation fuels from petroleum residua to low levels, it is very necessary to investigate the distribution of sulfur-containing compounds for the processes and desulfurization of residua. In the past, a number of methods have been reported for the isolation of sulfur compounds from petroleum based on distillation and/or mercuric chloride adduct formation. Most of these procedures are tedious and/or applicable only to the isolation of individual sulfur-containing compounds from petroleum and other fossil fuels. In this paper the crude oil from Russia was distillated to get the distillates and the atmospheric residua (AR) was further distillated under vacuum to get VGO fractions and vacuum residua (VR). The AR and VR were deeply cut into a number of fractions by supercritical fluid extraction and fraction (SFEF) respectively. A simple method used to determine the quantity and distribution of sulfur compounds in petroleum fractions was based on the ability to selectively oxidize the sulfur atom and large difference in polarity between the oxidized and non-oxidized forms. IR and element analysis were applied in the quantitative determination of sulfur species and their distributions. It is shown that the isolation of sulfide and thiophenic compounds from petroleum residua are obtained in a high yield and the sulfur is found in light, medium and heavy fraction of residua. The quantity of sulfides varies from 0.29% to 0.72% in fractions of VR and from 0.29% to 0.96% in those of AR; and the thiophenic compounds are from 1.19% to 1.50% in fractions of VR and from 0.67% to 1.43% in those of AR. The dominated sulfur type is thiophene in which the sulfur content is over 70% of total sulfur and the minority is sulfide. When fraction becomes heavier, the absolute sulfur contents in both forms will increase. However, the relative content of thiophenic sulfur decreases while that of sulfide increases.