Alan J. Power

Phenolic compounds in Bass Strait distillate fuels: their effect on deposit formation

Abstract Approximately 100 phenolic compounds have been identified in a caustic extract from catalytically cracked light cycle oil of Bass Strait origin. No other classes of compounds were found in the extract, which contained wt % of sulphur and nitrogen. Addition of the extract to other, more stable distillates caused them to yield increased amounts of total insoluble material during thermal ageing. Infrared spectroscopic evidence indicated that oxidative coupling of the phenols was the most probable mechanism responsible for the increased instability of the fuels. The role of phenolic oxidative coupling, in conjunction with other fuel degradation mechanisms, is discussed.

Accelerated oxidation of diesel distillate: Infrared spectra of soluble and insoluble gums

Abstract An infrared spectroscopic study of some products associated with petroleum diesel distillate instability is described. Spectra of soluble and insoluble gums which formed in the fuels during accelerated and ambient ageing are compared. The results indicate that gums derived from accelerated ageing are not the same as those which form during ambient storage. Spectral features relating to the chemical structures of gum components are discussed.

Characterization of distillate fuel sediment molecules : functional group derivatization

Abstract The nature of some of the functional groups containing oxygen and/or nitrogen atoms present in aged fuel sediments has been examined. Evidence is presented which indicates that aged diesel distillate fuel containing unhydrotreated light cycle oil forms sediment that contains an extensive network of aromatic hydroxyl groups. Acylation of fuel sediment, in particular benzoylation with benzoyl chloride, gave a very high conversion of aromatic hydroxyl groups to phenyl esters, as shown by analysis of infrared spectra of the original and derived sediments. Benzoyl chloride does not react directly with indolyl nitrogen and consequently no 1-benzoylindole moieties were expected or detected in the product. Acetylation of sediments with acetic anhydride, while providing some evidence of the formation of 1-acetylindole amide species, gave a high yield of acetate esters. There was little evidence of significant amounts of ketones in the sediment as shown by lack of oxime formation upon reaction with hydroxylamine hydrochloride. Boiling the sediment with 20% NaOH solution caused significant losses from the sediment of species containing sulphonyl groups, possibly originating in the sediment from sulphonic acids in the fuel.

Thermal degradation of aramids—Part II: Pyrolysis/gas chromatography/mass spectrometry of some model compounds of poly(1,3-phenylene isophthalamide) and poly(1,4-phenylene terephthalamide)

Abstract The thermal degradation reactions of seven aromatic amides which are structurally related to the commercial aramids Kevlar (poly(1,4-phenylene terephthalamide)) and Nomex (poly(1,3-phenylene isophthalamide) have been investigated in the temperature range 450 to 700°C by pyrolysis/gas chromatography/mass spectrometry. Benzanilide, N , N ′-dibenzoyl-1,4-phenylenediamine, N , N ′-dibenzoyl-1,3-phenylenediamine, N , N ′-diphenylterephthalamide, N , N ′-diphenylisophthalamide, N -(4-aminophenyl)-benzamide and N -(3-aminophenyl)benzamide all gave very low yields of carbon oxides and water. The structures of the higher molecular weight products were related to those of the parent compounds and their yields are presented quantitatively. The principal mechanism for thermal cleavage of the amide bonds in the N , N ′-dibenzoylphenylenediamines is mainly heterolytic, while for the other compounds thermal cleavage of the amide bonds is homolytic. The relationship between the pyrolysis products of the model compounds and those of the corresponding aramids is discussed.

Infrared spectroscopy of carbonyl species in oxidised diesel distillates

Abstract The extent of molar carbonyl group formation in some diesel distillates has been shown, using semiquantitative infrared difference spectroscopy, to differ by about an order of magnitude for three different fuel aging conditions (100 °C/168 h/O2 atmosphere: 95 °C/16 h/O2 sparge; ambient storage ≈10−3: 10−4 10−5 M). This may partly explain the known unreliability of accelerated oxidation techniques for predicting fuel storage stability. It has also been shown that CO species present in steam-jet gum residues do not represent those in oxidised fuels prior to evaporation.

The effect of vehicle filter media characteristics upon the filterability of automotive diesel fuel

Abstract Clusters of organic particles (up to 25 μm) were found to pass through vehicle filter media of 10 μm nominal pore size but to be retained by filters of 2 μm nominal pore size. The clusters were formed from individual particles of organic matter up to 2 μm diameter resulting from the storage degradation of diesel fuel. In contrast, a suspension of a silica dust of similar individual particle size to the organic particulate matter clusters, was largely retained by the vehicle filters. As a result of the dust particles being retained in the voids of the filter media, the vehicle filters were more rapidly blocked by the silica dust than the organic particulate. The probability of the clusters of organic particulate matter passing through a filter paper are reduced by the presence of other insolubles such as microbiological and inorganic material. Once retained, the clusters of small spheres may be moulded to fill voids in the filter media. In these circumstances, the presence of organic particulate matter in fuel will lead to very rapid filter blockage.

Fuel stability foam: a new means of distillate fuel stabilization

Abstract A new method of distillate fuel stabilization using a flexible polyurethane fuel stability foam (FSF) is reported. The degradation of fuel aged in contact with 0.2–0.4 g FSF per litre of fuel was decreased by greater than 90% as determined by formation of total particulate matter. The filterability of the treated fuel approached that of unaged fuel, and a reduction in fuel darkening was observed. FSF displaces