A small change in the surface polarity of cellulose causes a significant improvement in its conversion to glucose and subsequent catalytic oxidation
•Highly reactive cellulose was prepared by adsorption of amino acids onto surface cellulose.•The adsorption of amino acids induced changes in roughness and polarity of cellulose.•Roughed and polar surface of cellulose is easily oxidised in the presence of gold-zeolite catalysts.•Gluconic acid selectivity is maximal when Au-HY zeolite is used.
Three different amino acids were adsorbed onto the surface of microcrystalline cellulose, which caused changes in the polarity and roughness at the cellulose surface. The adsorptions partially modified the hydrogen bonding network of the cellulose structure, leading to more reactive cellulose residues that were facilely oxidised to gluconic acid by oxygen in the presence of gold zeolite supported catalysts. The conversion of cellulose and the selectivity for gluconic acid was controlled by the identity and amount of amino acid adsorbed onto the cellulose and the extra-framework cation in the zeolite support.
Graphical abstractScavenging the cellulose's surface: Different amino acids were adsorbed on cellulose, inducing changes in the polarity, the roughness and the hydrogen bonding network, leading to more reactive celluloses which were relatively easy oxidised to gluconic acid by O2 in the presence of a gold catalyst. The conversion of cellulose and the selectivity for gluconic acid was a function of the nature and amount of amino acid adsorbed on cellulose.Figure optionsDownload full-size imageDownload as PowerPoint slide
Journal: Applied Catalysis B: Environmental - Volume 144, January 2014, Pages 528–537