Abstract
Background: Isomerization of glucose to fructose is recognized as one of the key reactions for the transformation of cellulosic biomass, a potent substitution for the depleting petroleum resources. Zeolites are among the most useful catalysts for the isomerization process and substantial achievements have been achieved thus far. A state-of-the-art review is given within this content, and catalytic mechanisms and competitive reactions are discussed as well.
Methods: We performed a comprehensive search of literatures and the qualities of retrieved papers were appraised using standard tools. Literatures that represent the substantial findings are highlighted reflecting the progresses made with regard to the isomerization of glucose to fructose catalyzed by zeolites.
Results: Substantial achievements have been made with regard to the zeolite-catalyzed isomerization of glucose to fructose. The joint experimental-computational studies provide insightful clues to reaction mechanisms; e.g., the isomerization reaction proceeds in sequence of pyranose ring opening, hydride shift from C2 to C1 (rate-decisive) and furanose ring closure while the epimerization reaction is characterized by the intramolecular 1,2-carbon shift; Both of the defects SnOH and proximate silanol promote significantly the isomerization reaction while proximate silanol disfavors the epimerization reaction.
Conclusion: On basis of the fruitful catalytic results obtained thus far, two outlets are put forward that should be given priority with regard to the utilization of cellulosic biomass, as the combination of the isomerization reaction with other catalytic processes and the exploitation of the direct transformation of cellulosic biomass to platform chemicals.
Keywords: Cellulosic biomass, Lewis acidic zeolites, catalysis, isomerization, reaction mechanism, transformation.
Graphical Abstract
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