Hydrotreatment of Sewage Sludge-Derived Hydrothermal Liquefaction Biocrude. Part II: Kinetic Model

A kinetic model comprising 11 component families, 153 distributed lumps, and 117 first-order reactions was constructed to represent the hydrotreatment of a sewage sludge-derived HTL biocrude. The model was based on 15 laboratory-scale experiments with biocrude solubilized in heptane in a batch reactor and contacted with a hydrotreatment catalyst under 100 bar of hydrogen. Experiments were of duration 0–5 h and performed at 350, 375, and 390 °C. The mass balance was closed to at least 87%, and reactor outputs were analyzed with reaction liquids quantified by structure and carbon number in the form of mass distributions. A reaction scheme with three sections (straight chains, aromatics, and heavy lumps) was proposed. Twenty-six kinetic parameters were estimated, all significant to more than 95%. Model outputs compare well with measured data.