Biobased jet fuel form orange peel waste: limonene hydrogenation using Raney-nickel catalyst

The composition of conventional petroleum-based jet fuel consist of branched alkanes, cycloalkanes, and aromatic compounds. Due to the importance of the ecological transition, it has become relevant to find bio-based alternatives to these molecules. One representative example can be p-menthane, a branched cycloalkane obtainable by hydrogenation of limonene.1 The latter is a terpene and the main constituent of citrus essential oil which can be retrieved from orange peel waste. Taking into account a production of about 70 Mt of oranges annually worldwide for which the peel constitute up to 50% of the fruit weight, the valorization of these orange peel represent a great opportunity.2 Typically, limonene hydrogenation (Fig.1) has been carried out using molecular hydrogen and Pt, Pd or Rh as catalysts.1,3 In order to verify the feasibility of the reaction using another source of hydrogen and less noble metal as catalyst, in this study the reaction was performed using Raney-Nickel as catalyst, sodium borohydride as hydrogen source and methanol as solvent. The reactions were carried out in autoclave, using limonene purchased from commercial sources. A Design of Experiment was set to statistically asses the impact of: temperature (30 – 60 °C), catalyst amount (0.3 – 0.6 g), sodium borohydride amount (0.2 – 0.6 g), time (6 – 24 h) and solvent amount (10 – 20 mL). After, limonene was extracted form orange peel waste using green solvents2 and tested at the optimized reaction conditions.