Catalyst Screening for Low-Temperature Stabilization of Furfural: Effects of Sulfur Poisoning

Biomass-derived fast pyrolysis oil (PO) represents a promising alternative fuel for aviation and heavy transport. However, its high content of oxygenated organic molecules necessitates catalytic hydrodeoxygenation (HDO) before it is viable to be sent to a refinery. Single-step upgrading processes have encountered significant challenges, particularly reactor plugging and catalyst deactivation. To address these issues, an initial stabilization step at lower temperatures has been proposed to stabilize the most reactive compounds in the oil prior to hydrodeoxygenation. In this study, a range of different carbon- and Al2O3-supported catalysts (Ni/Al2O3, sulfided NiMo/Al2O3, Ru/C, Pd/C, Pd/Al2O3, Pt/C, and Pt/Al2O3) were evaluated for furfural stabilization in a batch reactor for 1 h with an initial pressure of 90 bar H2 and 180 °C with and without sulfur present. Sulfur tolerance was assessed by repeating all experiments with the addition of 1170 wt-ppm sulfur to the feedstock. The most active catalysts—Ni/Al2O3, Ru/C, Pd/C, and Pd/Al2O3—also exhibited the highest susceptibility to sulfur poisoning. Although Pt/C did not demonstrate the highest overall activity, sulfur addition appeared to enhance its performance, both in terms of furfural conversion and liquid yield of desired products.