Molecular Composition And Distribution Of Heavy Oil In Coal Direct Liquefaction

The liquid-solid products obtained in the process of coal direct liquefaction were separated by distillation and the coal direct liquefaction oil with boiling point above360?was called coal direct liquefaction heavy oil.Only by deeply understanding the direct coal liquefaction of heavy oil at the molecular level can we reasonably explain the problems encountered in its processing,and develop and process new technologies and catalysts in a targeted manner to maximize the value of coal direct liquefaction of heavy oil.This paper used coal direct liquefaction heavy oil as raw material.The main research contents and results are as follows:?1?The basic properties of coal direct liquefaction heavy oil were analyzed and a set of separation method was established.The H/C ratio of coal direct liquefaction heavy oil was lower than that of petroleum-based heavy oil,and with the deepening of distillation,the H/C ratio was decreasing,the aromaticity was increasing,the content of resin and asphaltene was increasing,and the total yield of four components was decreasing.?2?The molecular composition and structural characteristics of the coal direct liquefaction heavy oil subcomponent compounds were obtained.Saturated components were mainly composed of hydrocarbon compounds.A total of 826 kinds of basic nitrogen compounds,481 kinds of non-basic nitrogen compounds and 333kinds of sulfur compounds were identified by ESI FT-ICR MS in aromatic components.A total of 1453 nitrogen compounds,215 sulfur-containing compounds,978 non-basic nitrogen compounds and 2054 oxygen-containing compounds were identified in a mixture of resin and asphaltene.The molecular composition and structural characteristics of the above compounds were identified from the three dimensions of molecular type,number of carbon atoms,and degree of condensation?expressed by DBE values?.?3?The distribution characteristics of heteroatom compounds in the sub-components of 360³80?,380⁴00?,400⁴20?and>420?were obtained.S₁ was the main sulfur compound in aromatics and the mixture of resin and asphaltene.The basic nitrogen compounds and non-basic nitrogen compounds in the aromatic were mainly N₁ compounds,while the basic nitrogen compounds in the mixture of resins and asphaltene were mainly N₁ compounds,and non-basic nitrogen compounds were mainly three kinds of compounds,N₁,N₁O₁ and N₁O₂.The main oxygen-containing compounds in aromatics and the mixture of resin and asphaltene were O₁^O₆,and the relative abundance of O₁S₁,O₂S₁ and other complex heteroatoms were low.?4?By adjusting the ratio of n-heptane and toluene,asphaltenes were separated into five sub-components called F1-F5 according to the polarity.Compared with the direct detection of asphaltene,the number of basic nitrogen compounds in the sub-components increased from 5 to 39,and that of non-basic nitrogen compounds from 6to 34,and that of nitrogen compounds increased greatly.?5?High resolution mass spectrometry can characterize heavy oil at molecular level,but it was usually non quantitative.In this paper,a quantitative characterization scheme of sulfur compounds in heavy oil was provided.The molecular composition of the sub-components was normalized by element composition,and the composition and distribution of sulfur compounds in aromatics,resins and asphaltenes of heavy oil from coal direct liquefaction were obtained quantitatively.