Activity in the cellobiose hydrolysis of the surface acid sites of tungstated zirconia catalysts

Abstract

International @ ENERGIE+SBE:AAUInternational audienceCellobiose (a disaccharide derived from the condensation of two glucose molecules linked by a ß(1?4) bond) can be obtained by enzymatic or acid inorganic hydrolysis of cellulose and cellulose rich materials. The difficulties connected to cellobiose hydrolysis are due to strong-inter- and intra-molecular hydrogen bonds which are formed from the eight free alcohol (COH) groups and three ether linkages of the cellobiose molecule. Only catalysts with strong protonic acidity (Brönsted sites) are suitable for this reaction. Moreover, when the heterogeneous catalytic reaction occurs in water, the catalyst has to maintain its acidity even in this protic and polar solvent which is known to quench the acidity of many good solid acids. A series of WOx/ZrO2 samples with various tungsten oxide loadings (120) wt.% was prepared by co-precipitation and their surface properties characterized in particular by NH3 adsorption microcalorimetry to determine the number and strength of acid sites. Concerning the acid site nature, a progressive increase of the amount of Brřnsted sites with the WO3 loading was observed. The catalytic reaction of cellobiose disaccharide hydrolysis showed a better catalytic performance on the highest WO3 loaded catalysts, associated to the presence of Zr-stabilized WOx clusters and a strong protonic acidity