Using novel analytical methodology Diana Catalina Palacio Lozano reveals detailed structural information of the diverse chemicals within highly complex bio-oils, paving the way for development of improved production methods
Renewable fuels are expected to play an important role towards decarbonisation of the transport sector, such as ships and planes, where electrification is difficult or impractical. Despite their potential, pure renewable fuels are rarely used as fuel. Instead, low percentages of biofuels (e.g. 5%) are blended with petroleum-derived fuels. The use of higher percentage blends is less common due to factors including vehicle modifications, consumer acceptance, and production-refining costs. A primary limitation for bio-oil production is the poor understanding of their complex chemical nature.
Existing characterisation techniques certainly do not reveal the whole picture of the composition of complex mixtures. Ultrahigh resolution mass spectrometry (UHRMS) experiments, for instance, allow the determination of individual molecular compositions. There is, however, an unknown level of ‘dark matter’ that cannot be detected as a consequence of experimental parameters and sample complexity. The uncertainty greatly increases when the structure elucidation is considered. It is well-known that molecules of the same composition can be found in different bonding arrangements (isomers). Each isomer corresponds to a distinctive chemical with unique properties. It is estimated there are a larger number of isomeric compositions merely containing carbon, hydrogen and oxygen atoms than stars in the observable universe (1046 to 1021)! Therefore, the structural elucidation of complex mixtures is the ‘holy grail’ for energy and environmental research.
Given the complexity of bio-oils, gaining structural insights for individual molecules in complex mixtures is currently challenging. My research explores the potential of an alternative method to reveal the fine detail of the chemistry in complex mixtures. We are interested in identifying the molecules that contain certain functional groups, such as aldehydes (that are generally unstable and react over time), and can perform chemical reactions to target those specific functionalities based on their reactivity (chemical derivatisation). A comparison of the compositions before and after derivatisation will reveal the highly reactive chemical entities, and therefore, those entities are more likely to contain the targeted functional group. Due to sample complexity, coupling of chromatographic techniques to UHRMS is required for this method, as it enables the isomeric separation required while detecting thousands of co-eluting species. We believe the derivatisation-separation-resolution method shown in Figure 1 can pave the way for the advanced refining approaches and the optimisation of bio-oil quality.
