Alan L. Chaffee

Polycyclic aromatic hydrocarbons in Australian coals. I. Angularly fused pentacyclic tri- and tetraaromatic components of Victorian brown coal

Abstract Analysis of the tri- and tetraaromatic hydrocarbon fractions of a brown coal sample from the Latrobe Valley, Victoria, Australia indicate the predominance of pentacyclic hydroaromatic components. Many of these have not been previously reported in the literature, but are obviously diagenetically related to triterpenoids naturally occurring in the biosphere. The components whose molecular structures have been confirmed, together with those for which tentative structural assignments are given, offer strong support for a theory of progressive diagenetic aromatization of C-3 oxygenated triterpenoids, commencing from ring A. Other compounds present in smaller amounts suggest that 1,2-methyl shift reactions also occur prior to or during aromatization. There is a notable absence of polycyclic aromatic hydrocarbons (PAHs) which can be diagenetically related to the steroid or extended-side-chain hopane skeletons.

Polycyclic aromatic hydrocarbons in Australian coals II. Novel tetracyclic components from Victorian brown coal

Abstract Gas chromatographic-mass spectrometric (GC-MS) analysis of a polycyclic aromatic hydrocarbon (PAH) fraction of a Victoria brown coal sample has revealed the presence of a novel series of tetracyclic triterpenoid derived components. The base peak of their mass spectra, at m/z 169, suggests an 8, 14-seco (C-ring cleaved) structural configuration with the triterpenoid derived A- and B-rings fully aromatized. Photochemically induced or acid-catalyzed processes are seen as two possibilities to account for the diagenetic formation of these compounds.

Chemical effects in gelification processes and lithotype formation in Victorian brown coal

Abstract Infrared and CP-MAS 13 C-NMR Spectroscopy, Py-GC-MS and Py-MS techniques have been applied to samples of the five main lithotypes occurring in the Latrobe Valley brown coal deposits in Victoria, Australia. The analyses are compared with data from samples of fossilized and gelified wood from the coal deposit. The lithotypes fall into two groupings, viz. Dark (D), Medium Dark (MD) and Pale (P), Light (L), Medium Light (ML) on the basis if depositional inputs. The Dark lithotype is more closely related to gelified wood whilst the Medium Dark lithotype relates to fossilized wood. The three lighter lithotypes show similarities one to another but are not strongly related to wood precursors.

Pyrolysis—gas chromatography of Australian coals. 1. Victorian brown coal lithotypes

Abstract Pyrolysis—gas chromatography (Py—g.c.) has been shown to be a useful technique for characterizing Victorian brown coal lithotypes. The pyrograms show marked changes in the predominance and distribution of specific molecular classes as a function of lithotype. Hydrogen-rich triterpenoid components are predominantly associated with the lighter lithotypes, whereas hydrogen-deficient phenolic components are more abundant in pyrolysates from the darker lithotypes. Carbon preference indices (CPIs) are >1 for the alkanes but

Aliphatic components of Victorian brown coal lithotypes

Abstract Victorian brown coal occurs in five major lithotypes distinguishable by colour index, petrography and bulk chemical analyses. The distributions of solvent extractable (free) and base hydrolysable (bound) n-alkanes, n-monocar☐ylic acids, n-ά,ω-dicar☐ylic acids, n-ω-hydroxycar☐ylic acids and n-alcohols were determined for samples of each of the five lithotypes (lithotype profile) and for seven samples of identical lithotype classification spanning a 100 m interval (depth profile) taken from a continuous bore core. The distributions of free molecular components in all classes are indicative of the predominant higher plant origin of this immature coal and provide strong support for the view that different lithotypes have derived from different, yet fairly specific paleobotanical communities. Despite an overall similarity in the distributions of aliphatic components from samples of identical lithotype classification, changes in the absolute concentrations and carbon preference indices (CPIs) of specific functional classes are observed in response to catagenetic influences even across the very small rank interval of the depth profile samples. Molecular distributions of bound components are similar to those of their free counterparts except that CPIs are generally lower and the relative contributions of lower molecular weight homologues (i.e.

The conversion of brown coal to a dense, dry, hard material

Abstract A technology has been developed for transforming run-of-mine brown coals into a dense, dry, hard product. Raw coal is attritioned in batch or continuous kneaders to a mean particle size of approximately 10 μm. This size reduction releases the water naturally occurring within the porous coal structure, such that a paste-like material results. The paste can then be easily formed into products of the desired shape and size by extrusion devices. A hard, low-moisture content briquette-equivalent product is produced by the evaporative removal of water at or near ambient atmospheric drying conditions. The resultant product exhibits considerable strength, which may be further improved by the addition of pH modifiers in the case of suitable coals. Advantages of this densified brown coal process are that a hard, dense, fuel product can be manufactured from a raw brown coal of high initial water content without the need for, or prolonged, expensive drying conditions at elevated temperature. The resultant product is suitable either as a briquette equivalent fuel, or as feedstock for the manufacture of smokeless fuels, chars and activated carbons. The product retains the Volatile and Fixed Carbon values of the raw coal but possesses a Net Wet Specific Energy equivalent to that of a high rank coal. The densified coal has an advantage over a black coal in that dependant upon the coal stock selected the mineral content can be quite low. The process is more general and has been applied to other feedstocks — a peat and some lignites as well as brown coals have been found suitable. The chemical analyses indicate the involvement of phenolic residues in the coal as reactive centres. Reactions of these residues are initiated by the shearing-attritioning step in which fresh and reactive surfaces of the coal particles are exposed. The reactive centres are brought together by extrusion allowing cross-linking reactions to occur during drying.

Pyrolysis—gas chromatography of Australian coals. 2. Bituminous coals

Abstract Pyrolysis—gas chromatography (Py—g.c.) was used to characterize quantitatively a series of high- to low-volatile bituminous Permian Australian coals. The levels of n -alkanes, n -alkenes and triterpenoids released by pyrolysis all decrease as a function of increasing rank and thus, the coal samples can be classified into three distinct groups. Carbon Preference Indices (CPIs) for alkanes and alkene/alkane ratios also decrease as a function of rank. The triterpenoids have exclusively the hopane skeleton. The hopane isomeric distributions exemplify the geological maturity of bituminous coals relative to brown coal (lignite). A significant correlation has been established between the level of n -alkanes and n -alkenes released under Py-g.c. conditions and the predicted oil yield by pyrolysis of these coals. Further development and application of the techniqueshould enable much to be learnt relating to the quality and yield of flash pyrolysis tars as well as the original coal macromolecular structure.