Light-driven (cross-)dimerization of terpenes as a route to renewable C15 – C30 crudes for fuel and lubricant oil applications

Non-fossil hydrocarbons are desirable for transport fuels and lubricant oils to reach a fossil carbon neutral economy. Herein, we show the production of such end-products from crude raw materials via the photosensitized dimerization of terpenes. Terpenes are hydrocarbons originating from renewable sources, such as forestry, industrial bio-waste and photosynthetically active microorganisms. Under irradiation at 365 nm, we observed high conversions of terpenes into dimers (e.g. 96.1 wt.%, 12 h for α-phellandrene), and remarkable results were obtained using simulated and natural sunlight (90.8 wt.% and 46.6 wt.%, respectively, for α-phellandrene). We show that the lower reactivities of some isomeric monoterpenes could be overcome by a cross-photodimerization with α-phellandrene. We also utilized the cross-photodimerization approach to obtain C15 and C30 products, combining mixtures of isoprene, monoterpenes and sesquiterpenes. Hydrogenation of the terpene dimers gave materials with physical properties suitable as high energy density fuels and lubricant oils. Finally, our preliminary analysis based on recent literature points to the commercial viability of this route to produce fuels and lubricant oils, as well as to a potential for reduction of the environmental impact compared to fossil-based routes.