PROPOSED NUCLEAR MAGNETIC RESONANCE METHOD OF DETERMINING THE AROMATICITY OF HYDROCARBON FUELS.
ARMY MOBILITY EQUIPMENT RESEARCH AND DEVELOPMENT CENTER FORT BELVOIR VA
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A new method of determining the aromaticity of hydrocarbon fuels is proposed. This method utilizes nuclear magnetic resonance spectroscopy to measure complexation of acceptor molecules by aromatic hydrocarbon donors in the fuel. Dichloromethane and nitromethane were found to be satisfactory acceptors for this purpose. Equations were developed for the general case of n different aromatic donors, each having a different concentration, equilibrium constant, and complexation shift and with the assumption of rapid chemical exchange of the acceptor among the n competing donors. For any unknown fuel, the acceptor shift is a precise, reproducible quantity which may be converted to volume per cent aromatics by means of a simple equation. The constants in this equation may be determined by standarization with any aromatic hydrocarbon or with any mixture of aromatics. The method is applicable to any liquid hydrocarbon fuel and, unlike many existing methods, is unaffected by olefins, dyes, and fluorescent compounds. The precision of the shift measurement is typically 0.4 Hz, which corresponds to 0.2 - 0.5 percent aromatics. Author
- Physical Chemistry