Известия Томского политехнического университета: Инжиниринг георесурсов (May 2019)
Low-molecular nitrogenous bases and sulphurous compounds of highly paraffinic and highly resinous oils
Abstract
Relevance of the research is caused by the importance of accumulation and systematization of data on the content and structure of heteroatomic components in high-paraffinic high-resinous oils for the effective solution of the problems of production, transport and processing of such alternative hydrocarbonic raw materials. Work aim of the research is to study the nature of distribution and structure of low-molecular aromatic heterocyclic nitrogen-containing bases and sulfur-containing compounds in oils with the raised content of solid paraffin hydrocarbons and resin-asphaltene substances. The methods used in the study: thermochemical degradation in the Pokrovsky reactor and Sheniger's burning, non-aqueous potentiometric titration, sulfuric acid extraction, liquid-adsorption chromatography over modified sorbents, IR-spectroscopy, GC-MS analysis. The results. The authors have determined the differences and similarities in distribution and composition of low molecular weight hydrocarbons and aromatic nitrogen bases and sulfur compounds in high-paraffin and high-resin oils with similar content of resin-asphaltene substances but different content of paraffin waxes have. It was found out that the investigated oil samples are characterized by similar molecular mass distributions of aliphatic hydrocarbons. Both oils contain n-alkanes from C12 to C34 and a maximum amount of C17 in their compositions. It was shown that there are high- and low-alkylated structures among low molecular aromatic nitrogen bases and sulfur compounds of high-paraffin and high-resin oils. With minor differences in the relative abundance of the latter, the fraction of compounds with a higher alkylation degree was significantly larger in higher-paraffin oil. The qualitative composition of low-alkylated aromatic nitrogen bases and sulfur compounds of high-paraffin and high-resin oils was found to be independent on their content in paraffin waxes and resin-asphaltene substances. In both samples, these heteroatomic components are represented by С3-С8 quinolines, С1-С6 benzoquinolines, С1-С6 dibenzoquinolines, С2-С4 benzothiophenes, С0-С4 dibenzothiophenes and С0-С1 naphtobenzothiophenes. At the same time, the distribution maximum for these compounds in the higher-paraffin sample is shifted towards the structures with a big aromatic-core size (benzoquinolines, naphtobenzothiophenes).
