Hydrous pyrolysis of Scenedesmus algae and algaenan-like residue

Algae are regarded as the form of biomass most likely to provide sufficient quantities of fuels without impacting our food supplies. Studies investigating the potential of hydrothermal treatment of algae to produce biofuels show that, in many instances, the produced oils do not resemble crude oils and have a high heteroatom content. In this study, Scenedesmus spp. algae and isolated algaenan, a type of biopolymeric cell wall in certain algae and an important precursor to some kerogens, are subjected to hydrous pyrolysis in efforts to mimic the thermal maturation occurring in sediments as a proxy for biofuels production. Our study shows that algaenan can be subjected to hydrous pyrolysis to yield a hydrocarbon rich mixture that resembles many fossil fuel crude oils. More importantly, separation of the algaenan prior to the hydrothermal treatment can yield a paraffin rich crude requiring little additional processing to attempt to reproduce the geological process that gave us crude oils from ancient Type I kerogen. Although it requires algaenan isolation as a prerequisite, this could be a first step in the direction of producing oils without need for further upgrading. Whole algae, however, yield additional oxygenated products derived from oxygenated biopolymers even though the paraffins derived from algaenan dominate.