Selective, one-pot catalytic conversion of levulinic acid to pentanoic acid over Ru/H-ZSM5

• Wet impregnation gives well-dispersed Ru on H-ZSM5 with well-preserved strong acid sites.
• The catalyst gives an excellent yield of 91.3% pentanoic acid directly from levulinic acid.
• Any catalyst deactivation proceeds mainly via coke deposition in H-ZSM5.
• Activity can be almost fully restored after regeneration by simple coke burn-off.

The direct conversion of levulinic acid (LA) to pentanoic acid (PA) has been studied with six 1 wt% Ru/H-ZSM5 catalysts at 40 bar H2 and 473 K in dioxane. The influence of ZSM5 cation form, Si/Al ratio and ruthenium precursor on metal dispersion and acidity has been assessed. A highly active bifunctional 1 wt% Ru/H-ZSM5 catalyst was developed to give a PA yield of 91.3% after 10 h. The PA productivity of 1.157 molPA g−1Ru h−1 is the highest reported to date. The simple preparation method allows for a significant fraction of ruthenium to be located inside the zeolite pores, providing the desired proximity between the hydrogenation function and the strong acid sites, which is key to the conversion of LA into PA. Coke buildup during reaction causes some deactivation, but activity can be almost fully restored after catalyst regeneration by simple coke burn-off.

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