Catalytic cyclodehydration of xylose to furfural in the presence of zeolite H-Beta and a micro/mesoporous Beta/TUD-1 composite material

The batch-wise and aqueous phase cyclodehydration of D-xylose to furfural (FUR) at 170 degrees C has been investigated in the presence of a composite material consisting of zeolite Beta nanocrystals (Si/Al = 12) embedded in a purely siliceous TUD-1 mesoporous matrix (BEATUD), characterised by elemental analysis, powder XRD, TEM and N-2 sorption. After 8 h the xylose conversion reached 98% and the FUR yield was 74%. The initial reaction rates for BEATUD and the bulk nanocrystalline zeolite Beta (BEA) were similar when expressed on the basis of the total amount of acid sites (Lewis + Bronsted) determined through FTIR analysis of adsorbed pyridine. However, the FUR yields at high xylose conversions of ca.98% were higher for BEATUD (74%) than for bulk BEA (54%). TGA and DSC analyses for recovered catalysts showed that BEATUD possessed a lower amount of carbonaceous matter after a catalytic run, suggesting that the improved performance of the composite may be due to favourable competitive adsorption effects caused by the surrounding silica matrix. By thermally removing the carbonaceous matter between consecutive batch runs, BEATUD could be repeatedly reused without loss of catalytic performance. (C) 2010 Elsevier B.V. All rights reserved.