Catalyst studies on the hydrotreatment of fast pyrolysis oil

Catalytic hydrotreatment is considered an attractive technology for fast pyrolysis oil upgrading to liquid transportation fuels. We here report an experimental study to gain insights in catalyst stability when using Ru/C catalysts for the hydrotreatment of fast pyrolysis oil (350 °C and 200 bar) in a batch reactor set-up. A considerable reduction in the liquid yield (55–30 wt.%), increased solids formation (3–20 wt.%), a reduction in the H/C ratio (1.24–1.08) of the liquid product and a lowering of the extent of methane in the gas phase was observed after a number of catalyst recycles. Characterization of the catalyst before and after reaction using TEM, chemo- and physisorption showed significant coke deposition and a decrease in pore volume and metal dispersion. The application of in-house prepared Ru/C catalysts for both the hydrotreatment of fast pyrolysis oil as well as phenol using different Ru-precursors (RuCl3, Ru(NO)(NO3)3 and Ru(acac)3) gave different results for the various catalysts with respect to product yield (45–56 wt.% for fast pyrolysis oil) and elemental composition of the liquid phase. A catalyst prepared from the precursor RuCl3 at a ruthenium loading of 5 wt.% showed the highest activity for the hydrogenation reaction of fast pyrolysis oil (H/C of 1.32 vs. 1.24 for the commercial Ru/C catalyst) and the lowest reduction in BET area and metal dispersion after reaction.

Figure optionsDownload as PowerPoint slideResearch highlights▶ Ru/C catalysts tend to deactivate during the hydrotreatment of pyrolysis oil. ▶ The deactivation mechanism involves metal particle clustering and coke deposition. ▶ Catalyst formulations based on RuCl3 as the precursor showed the highest hydrogenation activity and lowest level of deactivation.