Bio-oil from biomass fast pyrolysis can be transformed into hydrogen (H2) or alkanes (C1–C6) by aqueous phase processing (APP). Low temperature hydrogenation of the water-soluble portion of bio-oil is a useful intermediate step of APP. In the present work, the anhydrosugar levoglucosan (LG) was selected as a model compound of the bio-oil aqueous fraction. LG hydrogenation was studied in a slurry reactor using heterogeneous Ru/C catalyst. Kinetic data were obtained experimentally in the range of temperatures, 398 to 433 K, H2 partial pressures, 0.69 to 2.07 MPa, initial LG concentrations, 0.6 to 3.1 mM and catalyst loading, 0.5 to 1.5 kg/m3. Langmuir–Hinshelwood–Hougen–Watson (LHHW) kinetics was used for modeling initial rates of LG disappearance. Two kinetic models assuming that surface reaction is rate-controlling reasonably represented the kinetic data. Model 1 assumed competitive adsorption of dissociatively chemisorbed H2 and LG, whereas model 2 was based on competitive adsorption of molecular H2 and LG. However, model II seemed to be not feasible, because of the low activation energy value and the assumption of reaction with molecular H2.

Aqueous phase processing (APP) of bio-oil represents a candidate technique for the production of renewable hydrogen (H 2 ) in a fast pyrolysis-based biorefinery. Low temperature hydrogenation of the water-soluble portion of bio-oil is a useful intermediate step of APP. In this work, the reaction kinetics of mild aqueous-phase hydrogenation of vanillin (VL), a model compound of the bio-oil aqueous fraction, was studied using Ru/C catalyst. The investigated aromatic aldehyde was converted to vanillyl alcohol (VA) and creosol (CR). Catalytic runs were performed in a slurry reactor in the 318−338 K range using different catalyst loadings (0.2−0.8 kg/m 3 ), initial VL concentrations (32.9 to 65.7 mM) and H 2 partial pressures (0.69− 2.07 MPa). The initial rates varied linearly with respect to both initial VL concentration and H 2 partial pressure. Four Langmuir− Hinshelwood−Hougen−Watson (LHHW) type kinetic models were proposed assuming that surface reaction was ratedetermining. These models were simplified to a second order reaction model based on bulk concentration of the reacting species. From the temperature dependence of the second order reaction rate constant, the activation energy was found to be 41.2 kJ/mol.

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