Characteristics of naphthenic and paraffinic hydrocarbons of residual oil from West Siberian crudes

This article examines the naphthenic/paraffinic hydrocarbons segregated by liquid chromatography from a residual oil after removal of the resins and solid hydrocarbons. The studied hydrocarbons were fractionated on the basis of molecular weight (by molecular distillation) and on the basis of the content of rings (by thermal diffusion separation in a laboratory column). The results of mass-spectrometric analysis indicate that the first fraction consists mainly of isoparaffins and naphthenes with few rings. The polycyclic condensed naphthenes are concentrated in the last fraction. The content of isoparaffins drops off and the content of condensed polycyclic naphthenic structures increases from the second fraction to the next to the last. It is concluded that the naphthenic/paraffinic hydrocarbons of the residual oil from mixed West Siberian crudes have a relatively narrow composition and therefore have similar physicochemical properties.