Comparative analysis of aromatic compounds steam reforming over Rh supported on γ-Al2O3

The steam reforming of bio-oil can provide a sustainable means to produce hydrogen, while tar steam reforming can significantly enhance the efficiency of the biomass gasification process. Bio-oils and tars are highly complex mixtures, and while there has been extensive research on the reforming of small oxygenates and aliphatic hydrocarbons, there have been comparatively much less studies on aromatics reforming. In the current work, we present a comparative study of the steam reforming of hydroquinone, benzyl alcohol and toluene, selected as model compounds of the aromatic fraction of bio-oils and tars with different
functional groups. The effect of temperature, partial pressure of reactants, and contact time is studied over a Rh catalyst supported on γ-Al2O3. Across the range of conditions studied, hydroquinone is found to be more reactive, followed by benzyl alcohol, and, lastly, toluene. The differences are attributed to the presence of hydroxyl groups in the case of the former two compounds, versus a methyl group in the case of toluene, effectively correlating activity with the O/C ratio in the compounds’ molecule. Nonetheless, similar pathways are observed, with methane, benzene, naphthalene and toluene (during hydroquinone and benzyl alcohol reforming) detected as products in addition to carbon oxides and hydrogen.