Separation and characterization of hydroxyl aromatics in complex fractions from nondistillable coal-derived liquids

Abstract

Complex hydroxyl aromatlc fractions isolated from nondlstlllable coal-derlved llqulds were separated by a comblnatlon of normal-phase and reversed-phase llquld chromatography. The normal-phase chromatographlc step effected the separation of hydroxyl aromatics Into mono-and dlhydroxyl fractlons. The mono-and dlhydroxyl fractlons from the coal-llquld sample were characterized with infrared and field-ionization mass spectrometry (FIMS). A monohydroxyl fraction of oils from a Kentucky coal-liquid sample was separated with an optimized reversed-phase chromatographlc system. The monohydroxyl fraction was completely eluted by uslng a comblnatlon of lsocratlc and gradient elution condltlons. The comblnatlon of reversed-phase liquid chromatography and FIMS provided a unique method for the characterization of the monohydroxyl fractlon of 011s from the Kentucky coal-liquid sample.The development and optimization of coal liquefaction processes for converting coal to environmentally acceptable liquids necessitate a fundamental understanding of coal liquefaction chemistry. This requires the development of new analytical separation methods and characterization procedures. However, no single method may suffice since sample composition and required compositional information will vary with the specific fuel and its intended use. Thus, if a coal-derived liquid is to be used as an energy source, compound-class separations may provide sufficient analytical information. On the other hand, if the coal-derived liquid is to be used as a petrochemical feed stock, separation and characterization of specific compounds may be required. Furthermore, the identification and elimination of toxic and carcinogenic compounds is necessary to reduce environmental and occupational health hazards.The extreme complexity of coal-derived liquids requires compound-class or functional-group-type separations prior to detailed characterization. Of particular interest are hydroxyl aromatics which are important in coal liquefaction processes and are abundant in coal-derived liquids. In addition, hydroxyl aromatics are important in many chemical processes and a number of exhibit carcinogenic and mutagenic activity ( I ) . Poirier and George (2), Trusell (3), and Yonko (4) have reviewed methods for separating coal-derived liquids according to compound types and the analytical methods used to characterize these fractions. In particular, Gorbaty et al. (5) have discussed the need for analytical methods for the separation and characterization of various oxygen functional groups in coal-derived liquids. Several methods have been developed for isolating and in some cases characterizing hydroxyl aromatic fractions from coal-derived liquid samples (2)(3)(4). However, very little work has been done in the subsequent separation and characterization of hydroxyl aromatic coal-liquid fractions.In general, both normal-and reversed-phase high-performance liquid chromatography (HPLC) have been used to separate hydroxyl aromatics (6-20, and several of these HPLC systems have b...

HPLC and31P NMR Analysis of Phenols in Coal Liquefaction Oils

“…The removal of phenols from organic materials such as coal-derived liquids can be carried out by liquid−liquid base extraction, or by solid-phase extraction on silica, alumina, or ion-exchange packings. − The separation and determination of individual phenols can be performed with GC and both normal and reversed-phase HPLC. − ,− Earlier it was shown 6 that solid-phase extraction (SPE) on a silica packing for the isolation of a coal−liquid polar fraction followed by reversed-phase high-performance liquid chromatography (RP HPLC) is a simple, rapid, accurate and convenient procedure for the determination of individual phenolic compounds. This method was adopted here despite its limitations which will be discussed later.…”