One-pot conversion of levulinic acid into gamma-valerolactone over a stable Ru tungstosphosphoric acid catalyst

In this paper ruthenium exchanged tungstophosphoric acid (TPA) catalysts with different ruthenium loading (Ru(x)TPA (x = 1,2,3)) were studied for conversion of levulinic acid (LA) into gamma-valerolactone (GVL) (a potential fuel/fuel additive). Studies were also conducted on a Ru/C catalyst as Ru/C catalysts have recently been reported to have significant promise for this reaction. Under the conditions used (130 degrees C, 1.0 MPa H-2, 2 h in 1,4 dioxane solvent) one of the prepared catalysts achieved excellent conversion and selectivity to GVL. This catalyst also compared favorably to Ru/C catalysts that have been previously studied in terms of rate of production of GVL per gram Ru. Characterization studies showed that Ru metal surface area and extent of Lewis and Bronsted acidity were characteristics that had a significant influence on the conversion and selectivity of the Ru(x)TPA catalysts studied. The best performing Ru(3)TPA catalyst was found to be highly recyclable with only a slight decrease in selectivity of GVL (from 100% to 98.3%) being observed after five cycles of testing.

Automated summary

In this study, ruthenium exchanged tungstophosphoric acid catalysts with different ruthenium loading were investigated for the conversion of levulinic acid into gamma-valerolactone. The results showed that the Ru metal surface area and Lewis and Bronsted acidity significantly influenced the conversion and selectivity of the catalysts. The best performing Ru(3)TPA catalyst was found to be highly recyclable with only a slight decrease in selectivity of GVL after multiple cycles of testing.