Applied Catalysis B: Environmental, Vol.200, 182-191, 2017
Direct conversion of biomass components to the biofuel methyl levulinate catalyzed by acid-base bifunctional zirconia-zeolites
A series of metal-zeolite hybrids was prepared by impregnation and deposition-precipitation methods and charaterized with different techniques. Catalytic performance of these catalysts on microwave assisted conversion of selected carbohydrates to the fuel component methyl levulinate (ML) in methanol was studied. It was demonstrated that metal oxide content/type and acid-base bifunctionality were closely correlated with substrate conversion and ML yield, respectively. Among various as-prepared catalysts, zirconia-zeolite hybrid ZrY6(0.5) with moderate acid-base site content (0.97 & 0.08 mmol g(-1)), high stability and porosity (average mesopore diameter: 6.2 nm) exhibited superior catalytic activity. At 180 degrees C, around 67-73%, 78%, 53% and 27% yields of ML could be achieved from monosaccharides (e.g., glucose, mannose and galactose), sucrose, starch and cellulose, respectively. The Zr-Y6(0.5) hybrid exhibited good stability, and could be reused for five times with ML yields of >= 63% from glucose. (C) 2016 Elsevier B.V. All rights reserved.