Multinuclear and Multidimensional NMR Tools for Characterisation of Bio-oils produced from BSG

An increase in fuel consumption over the last decade has introduced the utilisation of biomass as a green and more sustainable form of energy. The use of biomass is one possible solution for the development of sustainable and green energy platforms. Brewers' Spent Grain (BSG) is one of the major by-products of the brewing process. It consists mostly of long, tough carbohydrate and lignin chains, thus, this the further use of the waste material
limited. However, such chains can be broken down by destructive heating, or pyrolysis, into a thick, tar-like oil. This bio-oil is a complex mixture containing not only alkanes and alkenes but also, oxygen-containing species such as alcohols, aldehydes, carboxylic acids, guaiacols, and water. The direct use of bio-oil as a fuel is limited by the presence of these species: it is typically, too acidic and contains too much water.
Therefore, the understanding of the chemical composition of these bio-oils is crucial, and more importantly quantifying the oxygen-containing species will give the insight as to what upgrading process is required. Nuclear Magnetic Resonance (NMR) is a widely used non-destructive/non- invasive analytical tool, giving quantitative information about the chemical species present in a sample. Bio-oils, however, are mixtures of many dozens, if not hundreds, of different compounds and the analysis of such complex mixtures is not simple.
In this project, we will react the oils with chemicals that will combine only with the oxygen-containing groups and label them with NMR-active nuclei such as fluorine and phosphorus. This method allows for the direct quantification and even identification of the detrimental oxygen-containing species in the oil samples. Quantitative NMR protocols will be developed, allowing for rapid, precise characterisation of oil samples and may be implemented on NMR software or as standalone packages. Multidimensional techniques, such as diffusion NMR, can be applied to obtain additional information about the oil samples, coupling the chemical information found in an NMR spectrum with physical information, such as molecular weight. The set of available derivatising compounds can be expanded, either to achieve better resolution in the NMR spectra or to selectively react with other functional groups in the oil samples.