The Interplay of Brønsted-Lowry and Lewis Acid Sites in Bifunctional Catalyst for the Biomass Conversion to Levulinic Acid

The integration of phosphotungstic acid and niobium oxide forms a bifunctional catalyst that demonstrates an interplay between Brønsted-Lowry and Lewis acid which is able to provide a synergistic effect for the conversion of biomass to LA. This bifunctional acid catalyst shows a higher yield of levulinic acid (LA) (16.4%) as compared to that of sole phosphotungstic acid (10.5%) or niobium oxide (13.2%), presumably caused by a higher selectivity at the tandem steps of the conversion reaction. The bifunctional catalyst was then doped to a lignin-derived carbon cryogel to mitigate the deactivation and leaching of the catalysts. The durability and thermal stability of the carbon cryogel allow the catalyst to recycle up to 3 times while retaining similar performance.