Thermal Dry Reforming of Bio-Oil Model Compounds

This work presents an experimental investigation of the thermal dry reforming of hydrocarbons and oxygenated compounds representative of biomass pyrolysis bio-oils. Acetol, furfural, phenol, and syringol were used as model oxygenated compounds, while methane and propane were selected as benchmark hydrocarbons. Acetol and furfural were considered as pure feeds, while solid phenol and syringol were dissolved in acetol and furfural, respectively. Experiments were carried out in a tubular flow reactor at atmospheric pressure over a temperature range of 800-1350 K, using diluted stoichiometric feed/CO₂ mixtures. Gas-phase products were analyzed online by micro-GC, while condensed liquids were characterized by GC-MS and Karl Fischer titration. The results show that thermal decomposition dominates at low and intermediate temperatures, whereas dry reforming becomes significant above approximately 1200 K for all oxygenated feeds and propane and above 1300 K for methane. For the acetol/phenol mixture, the presence of phenol does not alter the onset temperature of dry reforming but enhances hydrogen yield at high temperature and reduces CO₂ conversion, while for the furfural/syringol blend, dry reforming becomes active above 1200 K; however, the contribution of thermal decomposition remains more persistent compared to the other feeds, as suggested by the H₂/CO ratio remaining above the stoichiometric dry reforming value even at the highest temperatures investigated. CO₂ conversion levels higher than 50% and up to 100% were achieved at higher temperatures (above 1300 K), depending on the feedstock. The hydrogen yield strongly depends on the chemical structure and varies significantly with temperature, reaching values close to 100% for acetol/phenol, furfural/syringol, and propane.