Oxygenated fuel additives from glycerol valorization. Main production pathways and effects on fuel properties and engine performance: A critical review

The projected growth of biodiesel world production has led to an increasing interest in finding new routes to valorize the large amount of glycerol produced linked to this biofuel obtaining process. One of these routes is glycerol transformation in value added products such as oxygen fuel additives. This review collects the latest advances in routes of glycerol valorization, considering the great majority of reactions with ketones and aldehydes, among other reactants. In order to justify the interest in these processes, this work includes a discussion of the main effects on fuel properties and engine performance. The characteristics that glycerol derivatives can provide to fuel blends, such as increasing in octane index, improving some cold flow properties or mitigating some negative aspects of other oxygenated compounds, such as environmental issues, flash point or gums formation will be exposed and discussed.