Robert E. Morris

Rapid Analysis of Jet Fuel Using a Handheld Near-Infrared (NIR) Analyzer:

A handheld near-infrared (NIR) analyzer was used to build partial least squares (PLS) models relating jet fuel properties to the spectral data (880–1570 nm). The properties included: API gravity, % aromatics, cetane index, density, 10%/50%/90% recovered distillation temperatures, freezing point, flashpoint, hydrogen content, and % saturates. The models were validated using leave-one-out validation of the training sets and by predicting an independent test set of fuels. The repeatability of the developed NIR methods was determined by performing replicate measurements on a single master analyzer. The reproducibility of the NIR methods was determined by performing measurements on multiple samples using five different analyzers. The results indicate that the NIR methods are useful for rapid monitoring of jet fuel quality at commercial airports during transport, storage, and distribution.

Influences exerted by metal deactivator on the thermal stability of aviation fuel in the presence of copper

ABSTRACT It has been shown that metal deactivator additives (MDA) exert a strong stabilizing effect on fuels when tested in the Jet Fuel Thermal Oxidation Tester (JFTOT). At low concentrations, MDA was found to be very effective in the JFTOT in reducing insoluble reaction products but had no significant effect on fuel oxidation. In the presence of dissolved copper, MDA acted to reduce tube deposition over regions of the tube at which temperatures were higher than 250°C. The deposits formed in the presence of copper at lower temperatures, which were not reduced by the MDA, were found to contain a high concentration of copper. MDA also partially counteracted the catalytic effects of dissolved copper on fuel autoxidation.

Improved peak selection strategy for automatically determining minute compositional changes in fuels by gas chromatography-mass spectrometry.

During the development of automated computational methods to detect minute compositional changes in fuels, it became apparent that peak selection through the spectral deconvolution of gas chromatography-mass spectrometry (GC-MS) data is limited by the complexity and noise levels inherent in the data. Specifically, current techniques are not capable of detecting minute, chemically relevant compositional differences with sufficient sensitivity. Therefore, an alternative peak selection strategy was developed based on spectral interpretation through interval-oriented parallel factor analysis (PARAFAC). It will be shown that this strategy outperforms the deconvolution-based peak selection strategy as well as two control strategies. Successful application of the PARAFAC-based method to detect minute chemical changes produced during microbiological growth in four different inoculated diesel fuels will be discussed.

Characterization of Fuel Blends by GC-MS and Multi-Way Chemometric Tools

Abstract Discrimination of fuel types in mixtures is a common need in remediation of fuel spills and the examination of fuel contamination issues. Available methods for performing these types of discrimination analyses generally rely on either spectroscopic or chromatographic analyses. However, these methods are limited when the compositions of the components of a mixture are very similar. In this study we have shown that many of these limitations can be overcome by including the additional dimension of compositional information provided by gas chromatography-mass spectrometry (GC-MS). Multidimensional chemometric techniques were successfully used to analyze GC-MS data to unravel multi-component properties of fuel blends. Both qualitative and quantitative features were derived from a series of diesel fuel and heavier heating oil blends.

Hydrosilation in Supercritical CO2: Synthesis of Fluorinated Polysiloxanes

Hydrosilation of poly(methylhydrosiloxane) with a fluorinated olefin in supercritical CO2 (scCO 2 ) using Karstedts Pt catalyst has been successfully demonstrated; results were compared with those obtained in a subcritical conventional solvent, i.e. toluene. Rates of hydrosilation were found to be dependent on solvent, reactant concentration, and reaction temperature. Levels of hydrosilation were 40-50%, depending on reaction conditions. Gel formation, which was not observed under any conditions in subcritical toluene, occurred in all reactions done in scCO 2 and accounted for up to 20 wt.-% of the final product mix.

Analysis of Twenty-Two Performance Properties of Diesel, Gasoline, and Jet Fuels Using a Field-Portable Near-Infrared (NIR) Analyzer

The change in custody of fuel shipments at depots, pipelines, and ports could benefit from an analyzer that could rapidly verify that properties are within specifications. To meet this need, the design requirements for a fuel analyzer based on near-infrared (NIR) spectroscopy, such as spectral region and resolution, were examined. It was found that the 1000 to 1600 nm region, containing the second CH overtone and combination vibrational modes of hydrocarbons, provided the best near-infrared to fuel property correlations when path length was taken into account, whereas 4 cm−1 resolution provided only a modest improvement compared to 16 cm−1 resolution when four or more latent variables were used. Based on these results, a field-portable near-infrared fuel analyzer was built that employed an incandescent light source, sample compartment optics to hold 2 mL glass sample vials with ∼1 cm path length, a transmission grating, and a 256 channel InGaAs detector that measured the above stated wavelength range with 5–6 nm (∼32 cm−1) resolution. The analyzer produced high signal-to-noise ratio (SNR) spectra of samples in 5 s. Twenty-two property correlation models were developed for diesel, gasoline, and jet fuels with root mean squared error of correlation – cross-validated values that compared favorably to corresponding ASTM reproducibility values. The standard deviations of predicted properties for repeat measurements at 4, 24, and 38℃ were often better than ASTM documented repeatability values. The analyzer and diesel property models were tested by measuring seven diesel samples at a local ASTM certification laboratory. The standard deviations between the analyzer determined values and the ASTM measured values for these samples were generally better than the model root mean squared error of correlation—cross-validated values for each property.

DEVELOPMENT OF A FILTER TO SELECTIVELY REMOVE COPPER FROM JET FUELS USING A POLY AMINE CHELANT IMMOBILIZED ON SILICA GEL

ABSTRACT Dissolved copper in fuels is generally rendered chemically benign by complexing with soluble chelating agents. However, this still leaves the copper in the fuel. By attaching suitable chelants to a solid support, copper can be selectively removed from the fuel by passing through a column packed with this material. We are evaluating a candidate system in which diethylenetriamine (DETA) is densely immobilized onto silica gel (DETA-Si). Previous studies have shown that this system will remove copper to below detection levels from jet fuel passed through columns at up to 30 mL/min. In this study, we show that the efficiency of DETA-Si to extract copper is not diminished in the presence of metal deactivating additives. Moreover, MDA does not extract copper from DETA-Si in lab-scale flow tests. The impact of filtration through silica gel and DETA-Si on thermal stability is also addressed.

Differences in Physical and Biochemical Properties of Thermus scotoductus SA-01 Cultured with Dielectric or Convection Heating

ABSTRACT A thermophile, Thermus scotoductus SA-01, was cultured within a constant-temperature (65°C) microwave (MW) digester to determine if MW-specific effects influenced the growth and physiology of the organism. As a control, T. scotoductus cells were also cultured using convection heating at the same temperature as the MW studies. Cell growth was analyzed by optical density (OD) measurements, and cell morphologies were characterized using electron microscopy imaging (scanning electron microscopy [SEM] and transmission electron microscopy [TEM]), dynamic light scattering (DLS), and atomic force microscopy (AFM). Biophysical properties (i.e., turgor pressure) were also calculated with AFM, and biochemical compositions (i.e., proteins, nucleic acids, fatty acids) were analyzed by attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy. Gas chromatography-mass spectrometry (GC-MS) was used to analyze the fatty acid methyl esters extracted from cell membranes. Here we report successful cultivation of a thermophile with only dielectric heating. Under the MW conditions for growth, cell walls remained intact and there were no indications of membrane damage or cell leakage. Results from these studies also demonstrated that T. scotoductus cells grown with MW heating exhibited accelerated growth rates in addition to altered cell morphologies and biochemical compositions compared with oven-grown cells.

Decomposition products of N,N′-disalicylidene-1,2-propanediamine adsorbed on 304 stainless steel

Abstract The compound, N,N′-disalicylidene-1,2-propanediamine, is commonly added to jet fuels to counteract the catalysis of thermally induced autoxidation by certain dissolved metals. The behavior of the metal deactivator additive (MDA) in thermally stressed jet fuel has raised questions on whether it decomposes after coming into contact with hot metal surfaces within the aircraft fuel system. Temperature programmed desorption (TPD) was performed to detect decomposition products of MDA on the 304SS surface. A method of scanning a relatively large mass range during desorption was developed to acquire 3-dimensional contour TPD (CTPD) plots of adsorbed species on the surface. Compounds with molecular masses of 107, 133, 232 and 290 were detected and their structures proposed. Conventional TPD spectra of selected molecular masses were then taken as a function of exposure. Mechanistic pathways for decomposition of MDA and formation of new compounds on the surfaces are proposed.

Liquid phase oxidation studies; Chemical ionization of alkyl ketones in an ion trap mass spectrometer

ABSTRACT The oxygen or hydroperoxide oxidation of various organo-sulfur compounds in both model and real fuels is an area that is presently under renewed investigation. Sulfur compounds of interest include thiols and disulfides in particular. Autoxidation reactions produce besides the expected sulfur oxidation products: sulfoxides, sulfones, thiosulfonates and sulfonic acids, small amounts of hydrocarbon oxygenates from the model fuel, dodecane. It was noted that the mass spectra of the oxygen species gave results that were instrument dependent. The results from an ion trap detector are quite different when compared to a dodecapole mass spectrometer.