Activity and stability of Mo2C/ZrO2 as catalyst for hydrodeoxygenation of mixtures of phenol and 1-octanol

• Mo2C/ZrO2 was tested as catalyst for HDO of phenol and 1-octanol.
• In situ XAS and XRD revealed carburization to take place at 550 °C.
• Slow deactivation took place over 76 h at 300 °C with the bio-oil model feed.
• Very fast deactivation took place when water was present in the liquid feed.

Mo2C/ZrO2 was investigated as catalyst for hydrodeoxygenation (HDO) of phenol in 1-octanol as a simplified bio-oil model system in a fixed-bed setup at 100 bar. Mo2C/ZrO2 selectively converted phenol to benzene above 320 °C. During long-term testing, limited stability of the catalyst was observed, with the conversion of 1-octanol and phenol decreasing from 70% to 37% and from 37% to 19%, respectively, over 76 h of operation. Repeating the experiment but also co-feeding 30% water, the catalyst deactivated completely within 12 h of operation. Thermodynamic calculations and in situ XRD analysis showed that Mo2C is transformed to MoO2 in the presence of water at the given conditions, and this was probably the source of deactivation in the experiments. Thus, Mo2C-based catalyst for HDO seems interesting, but requires further stabilization or regeneration of the carbide phase as bio-oil contains high levels of water and water is a by-product during HDO.

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