Synthesis of ethyl levulinate from bread waste and its application as a versatile bio-additive for spark ignition internal combustion engines

The world is going towards an important energy transition phase, due to environmental and socio-economic factors, which will lead to a progressive transition from fossil to renewable energy sources. A possible alternative to fossil fuels is represented by the adoption of biofuels for internal combustion engines. This solution does not involve drastic changes in the systems of distribution and use of energy, thus the existing infrastructures can be directly employed. Moreover, biofuels allow a significant reduction of net CO2 emissions, deriving from renewable resources and waste. In particular, oxygenated compounds are attracting great attention, and among them, alkyl levulinates appear extremely promising. In this work, for the first time, the one-pot synthesis of ethyl levulinate (EL) was studied starting from bread waste, an abundant waste of the food supply chain, adopting high gravity conditions (10 wt%). The influence of temperature, time and catalyst loading on the synthesis of EL was investigated and a yield up to 57 mol% was reached under the best reaction conditions. The utilization of EL as a bioblendstock in gasoline engines was then tested at unprecedentedly high loadings (up to 40 vol%) without significant changes in engine performance.