Characterization of Middle-Temperature Gasification Coal Tar. Part 1: Bulk Properties and Molecular Compositions of Distillates and Basic Fractions

Abstract

A middle-temperature coal tar (MTCT) was distilled into multiple narrow boiling point fractions. The MTCT and its distillate fractions were subjected to bulk property analysis and molecular compositional characterization by gas chromatography–mass spectrometry. Acid/basic liquid extraction was performed to separate the MTCT into acidic, basic, and neutral fractions, which were characterized by positive-ion electrospray ionization (ESI) Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometry. The dominant compounds in MTCT were aromatics, phenols, and normal alkanes. The number of carbon atoms in the substituent chains varied over a relatively broad range for each homology. The composition of narrow distillate fractions varied: light naphtha (<100 °C) had a high benzene content, which is an unsuitable gasoline blending stock; middle distillates (160–240 °C) enriched with phenols, which is a good extraction feedstock for chemical products; and heavy distillates (>240 °C) are a hydrotreating feedstock for clean fuel production. The MTCT had large amounts of acidic and basic components, consisting of oxygen- and nitrogen-containing molecules. The basic fraction accounted for 2.68 wt % MTCT. Only nitrogen compounds in the MTCT could be detected by positive-ion ESI. Most of the oxygen-containing molecules exhibited a weak acidity and were partially extracted into the acidic fraction. Basic nitrogen compounds co-existed in the acidic, basic, and neutral fractions of MTCT. However, the molecular compositions of basic nitrogen compounds were different among these fractions: molecules with low carbon numbers and high aromaticities were found in the acidic and basic fractions, whereas mono-nitrogen basic compounds were abundant in the neutral fraction.

Insight into the structural features of Zhaotong lignite using multiple techniques

“…As a non-destructive technology, XPS analysis cannot provide detailed information on nitrogen occurrences in coals at molecular level. Fourier transform ion cyclotron resonance mass spectrometer (FT-ICR MS), which possesses ultrahigh resolving power (>300,000) and mass accuracy (<1 ppm), has been widely used to characterize oxygen-and nitrogen-containing compounds in complex mixtures, such as petroleum [19][20][21], coal-derived liquids [22][23][24][25][26][27], and bio-oils [28,29]. Rathsack et al [23] investigated molecular composition of the liquid products from pyrolysis of a German lignite using electrospray ionization (ESI) FT-ICR MS. Their results exhibit that compounds detected are dominated by O x (x = 1-12) species and possible structures were proposed based on double bond equivalent (DBE, i.e., rings plus double bonds).…”

“…Rathsack et al [23] investigated molecular composition of the liquid products from pyrolysis of a German lignite using electrospray ionization (ESI) FT-ICR MS. Their results exhibit that compounds detected are dominated by O x (x = 1-12) species and possible structures were proposed based on double bond equivalent (DBE, i.e., rings plus double bonds). Shi et al [25][26][27] used ESI FT-ICR MS to analyze a middle-temperature coal tar. They only focused on N 1 species for neutral nitrogen compounds (NNCs).…”

Identification of basic nitrogen compounds in ethanol-soluble portion from Zhaotong lignite ethanolysis by positive-ion electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry

“…Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) proved to be a powerful technique for molecular characterization of extremely complex samples, such as petroleum [20][21][22][23], coal-derived liquids [24][25][26][27][28], pyrolysis bio-oils [29][30][31], and dissolved organic matter in waste water [32]. It has an ultrahigh broadband mass resolving power (exceeding 200,000) and mass accuracy (<1 ppm), allowing for baseline resolution of closely spaced isobaric species as well as distinct assignment of a unique elemental composition to each mass spectral peak.…”

Identificação De Compostos Aromáticos Presentes No Alcatrão De Hulha Proveniente Da Gaseificação Do Carvão Mineral De Candiota-Rs

“…Os resultados mostrados na Figura 4, mostram maior presença de fenol no filtrado do alcatrão de hulha, concordando com o descrito por Pan et al (2012). Segundo os autores, as alíquotas contendo tolueno, fenol e antraceno foram produzidas entre 160 e 240 °C, e não continham destilados pesados.…”