Abstract
Crude oil is the worlds most widely used energy resource and with an ever-growing demand for the finite supply, petroleum companies are now extracting less accessible reserves holding lower quality crude oil. However modern exploitation has led to new concerns over the toxicity of increasing extraction waste and refinery problems (e.g. pipeline deposits). One class of compounds associated with causing some toxicity in process waters and corrosion in pipelines, is the carboxylic or so-called naphthenic acids (NA). Early research identified NA as acyclic and monocyclic structures, however recent interest in acid-rich crudes has led to the identification of bi- and tricyclic, aromatic, steroidal monocarboxylic acids and long chain acids with multiple acid moieties (e.g. C80-tetra acids), principally by improved gas chromatographic methods. The current research attempts to identify NA from both petroleum and oil sands but in this case by first converting NA to their hydrocarbon equivalents using a three-step conversion whilst maintaining the integrity of the skeletal carbon structure. This should result in improved chromatography due to the reduced polarity of the analytes, enhancing structural elucidation. So far, in the initial 3 months, three known model bicyclic acids have been reduced to their corresponding alcohols. Reactants and products have been characterised by FT-IR spectroscopy, GC-FID and GC-MS of derivatives. Subsequent work will involve dehydration to the alkenes and catalytic hydrogenation to the alkanes. Results from the model compounds will act as a preliminary indication of the success of the synthetic conversion for unknown and more complex petroleum mixtures. Successful identification of the NA structures present in petroleum will help to focus studies on the quality and processing of less favourable crude oils with the overall aim of making the extraction of such crudes more efficient and cost-effective, with less environmental impact.