Separation And Analysis Of Middle/Low Temperature Coal Tar In Shaanxi

Middle and low temperature coal tar?M/LTCT?is a major by-product from the"semi-coke"production.Organic chemicals separated from M/LTCT are high value chemicals,especially condensed aromatic compounds.It is imperative to develop technologies for separating condensed aromatic compounds from M/LTCT which is essential for the high value utilization of coal coking products.In this study,the fractions of M/LTCT in Shaanxi(MLTCT_SX)were separated by directional separation followed by separating of some pure organic compounds by using medium-pressure preparative chromatography and column chromatography.High-resolution mass spectrometry with multiple ion sources is used to characterize organic components that are difficultly identified by traditional analytical methods.The compositions of M/LTCT_SX are more comprehensively revealed at the molecular level and insights into aromatic nucleus of the M/LTCT_SX are provided.Then,M/LTCT was separated into group components by solvent extraction.The hydrogen bond which plays an important role in solvent extraction was analyzed by Gauss calculation.The M/LTCT_SX was sequentially extracted with petroleum ether and methanol,and the resulting extracts were analyzed by FTIR and GC/MS.The methanol extract of M/LTCT was analyzed by ESI Orbitrap MS and GC×GC/TOF-MS.The GC×GC/TOF-MS detectable compounds are mainly composed of aromatic compounds,including aromatic hydrocarbons,phenols,aryl ketones,aromatic furans,aromatic acids,aromatic alcohols,aromatic esters,pyridines and quinolines,among which the aromatic hydrocarbons have the highest content.Among the heteroatom-containing aromatic compounds,the oxygen-containing compounds content is the most abundant.The main aromatic nucleus mainly include benzene ring,anthracene ring,anthracene ring,naphthalene ring,anthracene ring,fluorene ring,anthracene ring,etc.The types of condensed aromatic rings are mainly cata-condensation,peri-condensation,and biphenyl condensation.The distributions of normal paraffins,branched paraffins,olefins,and naphthenes provide significant clues to the coal-forming process of the raw coal of the M/LTCT_SX.Aquatic plant wax could play an important role in the formation of organic matter in the coal.The lower pyrolysis temperature of coal allows many structurally specific compounds in coal to be retained in M/LTCT_SX.ESI Orbitrap MS detected thousands of heteroatom-containing organic compounds in the M/LTCT_SX.Condensed aromatic compounds are dominant.The condensation degree?aromatic ring number?of condensed aromatic compounds was investigated.The type and occurrence form of the hetero atom?nitrogen,oxygen,sulfur,etc.?in the aromatic nucleus,the type and position of the substituent on the aromatic nucleus,and the content of these condensed aromatic compounds were also discussed.The structural characteristics of organic matter in the methanol insoluble fraction of the M/LTCT_SX were explored by FTIR?XPS and TGA.Directional isolation of group components in M/LTCT_SX using medium-pressure rapid preparative chromatography with petroleum ether,petroleum ether and ethyl acetate mixture solvent?with different volumetric ratio?,and ethyl acetate as eluents with the aid of UV on-line detector was investigated.The group components in the M/LTCT_SX were separated into aliphatic hydrocarbons,arenes,oxygen-containing organic compounds?OCOCs?,and nitrogen-containing organic compounds?NCOCs?.The aromatic component was analyzed by APPI-TOMMS with toluene as additive.The OCOCs,NCOCs were analyzed by using in-source collision-activated dissociation?ISCAD?Orbitrap MS with ESI.The position on the aromatic nucleus was determined.The arenes and OCOCs were finely separated,and some compounds in them were isolated as the pure organic compounds.Using C18 as filler,water and acetonitrile as reverse eluting agents,the aromatic components are separated by medium-pressure rapid preparative chromatography.The PE,the mixture of PE and ethyl acetate of different ratios,ethyl acetate,the mixture of ethyl acetate and methanol of different ratios,and methanol as the eluent are sequentially used,and the toluene,naphthalene,methyl naphthalene,anthracene,phenanthrene,and other organic compounds were finely separated by using silica gel as filler.The PE,different ratios of PE and dichloromethane mixture,and dichloromethane as eluents,and alkaline alumina as filler,the oxygen-containing organic components were further isolated by medium-pressure rapid preparative chromatography.The sub-fractions were further finely separated with basic alumina column chromatography to obtain pure organic compounds such as phenol,naphthol,and phthalate.The solvent-extracted separation of the group components of the M/LTCT_SX was carried out,and the neutral oil,polar oil,and asphaltene were successfully separated by the self-designed solvent extraction and separation medium and small test device.Using methanol...phenol?MP?,methanol...naphthol?MN?,methanol...benzofuran?MF?,methanol...cyclopentanone?MK?,methanol...benzoic acid?MB?,and methanol...methyl butyrate?MM?systems,the hydrogen bond involved in solvent extraction was investigated by Gaussian calculation.