Thermodynamic analysis and reaction routes of steam reforming of bio-oil aqueous fraction

Steam reforming of the bio-oil aqueous fraction is a potential process to produce hydrogen. Therefore, to perform a thermodynamic study of this process can be interesting to determine the most favorable operating conditions. The calculations were made using a model compound and an aqueous fraction of a specific bio-oil. The data were obtained at different temperatures and for different steam(S)/fuel(F)ratios. Thermodynamic data showed that the behavior of model compounds was very similar to the one observed for the aqueous fraction of bio-oil. Therefore, acetic acid was used as a model compound of the aqueous fraction of bio-oil in the experimental tests. Temperature-programmed acetic acid desorption, temperature programmed reaction and steam reforming reactions were conducted. The experimental results were correlated with data predicted by thermodynamic analyses. There was a good correlation between the experimental results and predicted by equilibrium calculations. It helped to clarify the possible reactions pathways that are present in the reform process studied. According to the results the steam reforming of acetic acid can follow two different routes: (i) acetic acid can be converted to acetone at intermediate temperatures or (ii) acetic acid is transformed into adsorbed acetate species (CH3COO*) followed by decomposition into acetyl species (CH3CO*).