Quantitative NMR Spectroscopy for the Analysis of Fuels: A Case Study of FACE Gasoline F

Abstract

A detailed experimental methodology is outlined, which allows for the measurement of quantitative 1 H and 13 C nuclear magnetic resonance (NMR) spectra of liquid hydrocarbons. Optimal experimental conditions are identified, which allow for the collection of entirely quantitative 1 H and 13 C NMR spectra; the most significant among these are shown to be the choice of solvent and the delay time utilized. A best practice for the interpretation of the measured spectra that utilizes heteronuclear single quantum coherence (HSQC) NMR spectroscopy is outlined. Use of the HSQC method allows for the expeditious determination of fuel-specific integral regions. Importantly, the use of HSQC is shown to be a convenient method for the identification of overlapping peaks. The fidelity of both 1 H and 13 C NMR spectroscopy for the analysis of liquid fuels is demonstrated through the analysis of a range of reference fuels of known composition. Atom type populations are calculated for the reference fuels using a defined set of operating equations. In general, the NMR spectroscopy measured atom type populations show a strong agreement with the known atom type populations. The uncertainty associated with these measurements is determined to be <3%; however, this does not take into account overlapping peaks. The experimental methodology is applied to the analysis of FACE Gasoline F. The NMR-derived atom type population is shown to be in good agreement with the previously reported detailed hydrocarbon analysis (DHA). Additionally, the potential for a synergistic relationship between NMR spectroscopy and DHA is highlighted through the identification of molecules present in FACE Gasoline F that were misidentified by the DHA.

Use of polypropylene pyrolysis oil in alternative fuel production

“…The authors propose to use NMR analysis not only for qualitative but also for quantitative determination of the amounts of compounds. Using NMR spectroscopy, Myers et al (1975) and Ure et al (2019) identified the pyrolysis compounds by class and calculated the content of paraffin, olefins and aromatic compounds in the pyrolysis oil obtained by slow PP pyrolysis. In their study, unlike ours, small amounts of aromatic compounds were detected.…”

“…The spectral data obtained show that the pyrolysis products have unsaturated compounds. According to the literature (Hesse et al, 2005;Ure et al, 2019), the signals obtained can be assigned to α-alkenes with a chemical shift of 100-150 ppm.…”

Methodology for the Development of Empirical Models Relating 13C NMR Spectral Features to Fuel Properties

“…93 Ure et al provides a similar comparison, identifying the absolute differences observed in a set of model fuels in their very thorough methods paper. 89 As noted by these authors' analyses, quantitative 13 C NMR spectra can be readily obtained.…”

Polymeric waste valorization at a crossroads: ten ways to bridge the research on model and complex/real feedstock

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