Abstract: A method and apparatus for thermolysing organic material. The method comprises steps of: A) feeding the material in a single-screw extruder (100), the extruder comprising —a cylindrical rotor member (1) having diameter (D) and length (L) and comprising a feeding zone (14), —the rotor member (1) arranged in a barrel (2), —the cylindrical surface of the rotor member (1) carrying cavity/cavities and/or projection(s) (5) arranged in helically extending rows, —the helically extending row(s) of the rotor member (1) having a pitch (P) and depth (d) in the feeding zone (14) of the rotor member, wherein —the relation of the depth (d) to the diameter (D) of the rotor member, i.e. d:D, is not more than 1:20, and —the relation of the pitch (P) of the rotor member to the diameter (D) of the rotor member, i.e. P:D, is not more than 1:4, B) heating the material in the single-screw extruder (100) to a flowable state, and C) thermolysing the material.

Abstract: A process for stabilizing pyrolysis oil includes hydrogenating fast pyrolysis oil with hydrogen reactant in the presence of ruthenium metal catalyst at a temperature of at least about 70° C. and at a pressure of at least about 600 psig to form a hydrogenated fast pyrolysis oil exhibiting an increase in viscosity of less than 10% after accelerated stability testing at 80° C. for 24 hours. The resulting hydrogenated fast pyrolysis oil can be characterized as stabilized to viscosity increase, and can be provided as a bio fuel oil.