Thermogravimetry−Photoionization Mass Spectrometry of Different Rank Coals

Abstract

Volatile matter evolved during pyrolysis of 20 different rank coals was studied by thermogravimetry-photoionization mass spectrometry (TG-PI-MS). The composition of the TGA effluent revealed several significant trends with coal rank. First, the relative intensities of peaks due to compounds containing oxygen such as C n H 2n O (n ) 2, 3, or 4), phenols, and dihydroxybenzenes decreased with increasing coal rank. Also, the relative intensities of peaks due to aromatic compounds such as naphthalenes, phenanthrenes, and pyrenes increased with increasing coal rank. Mass signals due to sulfur compounds evolved from coal showed qualitative correlations between CS 2 (%TIC) and pyritic sulfur content and between CH 3 SH (%TIC) and aliphatic sulfur content. Several of the coals were extracted with a solvent to remove the soluble portion of the coal. TG-PI-MS analysis of the raw coal, extracted material and coal residue remaining after solvent extraction produced very similar mass spectra. These results suggest that the majority of the compounds observed by TG-PI-MS are products of thermal cleavage of bonds within the coal structure. This conclusion is further supported by 337 nm laser desorption mass spectrometry of the solvent extracts. The results from these analyses suggest that volatile matter, like coal itself, consists of compounds with a range of molecular weights but with similar molecular structures.

Chemical species associated with the early stage of soot growth in a laminar premixed ethylene–oxygen–argon flame

“…Each graph in these figures is a plot of signal intensity of the m/z of interest normalized by the total intensity of all ions in the spectrum versus HAB. Normalized intensities are highly reproducible with the photoionization technique [38][39][40]. Representative aliphatic peaks corresponding to methyl (CH 3 , 15 m/z), ethyl (C 2 H 5 , 29 m/z), butadiene (C 4 H 6 , 54 m/z), and octene (C 8 H 16 , 112 m/z) are shown in Fig.…”

Caracterização detalhada de material de referência certificado de carvão brasileiro

“…Na curva DTG, o pico maior (em torno de 499 °C) é provavelmente constituído por vários processos de pirólise. Segundo Zoller e colaboradores, 29 esse pico pode corresponder à clivagem de ligações no interior da rede macromolecular de carvão e de dessorção térmica dos compostos de estruturas termicamente menos estáveis. O ombro observado próximo a 557 °C é identificado como uma decomposição térmica da pirita.…”

Restoring Sustainable Forests on Appalachian Mined Lands for Wood Products, Renewable Energy, Carbon Sequestration, and Other Ecosystems Services

“…We were also aware that the more volatile carbon constituents of geogenic origin in the mine soil samples will be oxidized to CO 2 leaving only the most resistant organic compounds in the sample unoxidized (Vorres 1998). Zoller et al (1999) have determined these highly resistant organic residues to be carbon particles of highly aromatic chemical structure within individual coal fragments. The latter could be measured by elemental C analysis using automated carbon analyzer.…”

“…Following carbonates removal by HCl fumigation (Harris et al 2001, Hedges and Stern 1984, Yamamuro and Kayanne 1995, the 30 soil mixtures were exposed to three thermal oxidation temperature levels: 375°C (adopted from Schmidt et al 2001); 550°C (Bendfeldt et al 2001, Schulten andLeinweber 1999), and 650°C (derived from Othman andShamsuddin 2003 andZoller et al 1999), for a period of 24 hours to determine the effect of temperature on the efficacy of thermal transformation of C to CO 2 of pedogenic C and the more volatile geogenic C forms in each sample. All SOC measurements for the 30 soil mixtures were replicated five times for a total of 450 measurements using the 16-step SOC estimation method.…”