Winston K. Robbins

Identification of acidic NSO compounds in crude oils of different geochemical origins by negative ion electrospray Fourier transform ion cyclotron resonance mass spectrometry

Abstract We present the selective ionization, resolution and identification of acidic NSO compounds in three crude oils of different geochemical origins by negative ion electrospray ionization (ESI) Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS). Selective ionization by ESI affords direct detection of neutral nitrogen compounds and carboxylic acids in petroleum without pre-chromatographic isolation. Ultra-high resolution/mass accuracy allows detailed and positive identification of acidic NSO compounds in the crude oils. Observed compositional differences reflect known crude oil properties/histories. Collectively, ∼14,000 masses, spanning 18 different heteroatomic classes, are identified unequivocally, demonstrating the potential of ESI-FT-ICR MS for geochemical applications.

A carbon-14 tracer study of the relative fractions of various fuel carbons in soot

The effect of fuel hydrocarbon structure on soot emissions was studied using a carbon-14 isotope tracer technique. A diesel engine or a laminar wick diffusion flame generated radioactive soot from a #2 diesel fuel containing 14Chydrocarbons. For the same diesel fuel, the individual soot yields of several carbon atom types were determined. For the diesel engine, the soot yield from aromatic carbons was about a factor of 1.5 greater than that from nonaromatic carbons. For the wick flame, the soot yield from aromatic carbons was about a factor of 2.0 greater than that from nonaromatic carbons. Interestingly, these differences in soot yield between aromatic and nonaromatic carbons within the same fuel are too small to explain the differences in soot yield between aromatic and nonaromatic fuels. This is consistent with the hypothesis that aromatic carbons increase soot emissions by greatly increasing the number of nascent particles while contributing only slightly more than other carbons to the final soot mass. It also shows that variations in fuel hydrocarbon structure have a minimal effect on the soot particle growth process, which produces most of the soot mass. The wick flame was set to give a soot yield that was 20 times greater than that of the diesel engine; yet, the carbon-14 concentrations in the soot were similar. This is expected if the formation of soot growth species from the original fuel molecules is independent of the amount of soot ultimately formed from the growth species. Also, the soot yield of a given carbon atom type was unaffected by the molecular weight of the hydrocarbon molecule that contained it. So for #2 diesel fuel, soot is produced equally from all points along the fuels distillation curve (molecular weight range) even though heavier fuels make more soot.

Model Compound Study of the Mitigative Effect of Crude Oil on Pipeline Corrosion

Internal corrosion of crude oil pipelines can lead to spills that can be very costly, both financially and environmentally. The corrosion is controlled mostly by mitigation methods, such as through design or by the use of corrosion inhibitors. However, it has been observed that some, but not all, crude oils can have an inhibitive effect on their own. There are different mechanisms for crude oils to mitigate corrosion, such as inhibition through the water phase by inhibitor-like molecules native to the crude oil, wettability alteration from water wet steel surface to oil wet, thereby limiting the access of the water to the surface, or by lowering the interfacial tension between oil and water and facilitating dispersion of water in oil, which reduces the likelihood of corrosion by keeping the water from being in contact with the steel surface. Model compounds representative of the naturally occurring surface-active compounds commonly found in crude oil were tested for their effect on corrosion inhibition, w...

Characterization of Highly Oxygenated and Environmentally Weathered Crude Oils by Liquid Chromatography Fourier Transform Ion Cyclotron Mass Spectrometry (FT-ICR MS)

Heavy and biodegraded oils exhibit an ever increasing oxygen complexity. Electrospray ionization (ESI) coupled to FT-ICR MS highlights the most acidic and basic oxygen species; however, quantitative and qualitative information about less polar oxygenated compounds is essential to understand both the source and, potentially, the modification pathways for oxygenated crude oils. Liquid chromatography (LC) is complementary to FT-ICR MS to deconvolve crude oils according to oxygen functionality, thereby enriching oxygen species that are not easily ionized or are present in low abundance. Ketones and carboxylic acids dominate most environmentally modified crude oils; however, phenols and polyphenols are also important intermediates in both biotic and abiotic modifications. Moreover, due to the nature of the refinement process, oxygen-containing species and their intermediates can serve as chemical tracers in produced water streams and areas of rapid thermal changes that lead to gum or deposit formation. Here, w...