Energy & Environmental Science vol:4 issue:9 pages:3601-3610
Innovative catalyst design holds the key to fundamental advances in the transformation of cellulose to chemicals and transportation fuels, both of which are vital to meet the challenge of increasing energy costs and the finite nature of fossil fuel reserves. Here we report on the functionalization, characterization and successful application of sulfonated hyperbranched poly(arylene oxindole)s for the direct catalytic conversion of cellulose to levulinic acid. The use of water-soluble hyperbranched polymers in combination with ultrafiltration is conceptually novel and opens new horizons in the aqueous-phase processing of cellulose substrates with various degrees of crystallinity. Compared to most conventional types of acid catalysts, these highly acidic polymers demonstrate superior catalytic performance in terms of both activity and selectivity. Additionally, this molecular approach can be successfully transferred to the acid-catalyzed degradation of other abundant biomass resources, including starch, inulin and xylan.