Aqueous-phase dehydration of xylose to furfural in the presence of MCM-22 and ITQ-2 solid acid catalysts


The H-MCM-22 zeolite possessing an MWW (medium-pore) framework and its delaminated counterpart. ITQ-2, with enhanced external surface area, are effective and recyclable solid acid catalysts in the batch-wise, aqueous-phase dehydration of xylose, at 170 degrees C. Up to 71% furfural (Fur) yield is reached at 98% conversion using a biphasic aqueous-organic solvent system (for the simultaneous extraction of Fur); using solely water as the solvent gives up to 54% Fur yield at 97% conversion. Sulfuric acid, used in an approximately equivalent amount to the total acid site concentration of the solid acids, gave 55% Fur yield at 93% conversion. Decreasing the Si/Al ratio of H-MCM-22 zeolite improves the acid properties and consequently the catalytic activity, without affecting significantly the Fur selectivity. While the delamination process considerably enhanced the external surface area of ITQ-2 in comparison to H-MCM-22, it caused modifications in the acid properties, leaving the two prepared materials with the same Si/Al atomic ratio of 24, on a comparable footing in terms of catalytic performance in the studied catalytic reaction. Nevertheless, these solid acid catalysts are fairly stable (similar Fur yields are reached in recycling runs; no structural modifications and no leaching phenomena were detected). (C) 2012 Elsevier B.V. All rights reserved.




Chemistry; Environmental Sciences & Ecology


Antunes, MM; Lima, S; Fernandes, A; Pillinger, M; Ribeiro, MF; Valente, AA

nossos autores


This work was partly funded by the FCT, POCTI and FEDER (project POCTI/QUI/56112/2004). The authors thank Dr U. D. Morales (Instituto de Tecnologia Quimica, CSIC, Universidad Politecnica de Valencia) for the valuable help with the recipe of ITQ-2; Marta A. C. Ferro for help with the TEM studies, and acknowledge the Portuguese network of electron microscopy, the RNME, FCT Project REDE/1509/RME/2005; Prof. C.P. Neto (University of Aveiro) for helpful discussions; Dr. F. Domingues (University of Aveiro) for access to HPLC equipment. S.L. (SRFH/BPD/23765/2005) and M.M.A. (SFRH/BD/61648/2009) are grateful to the FCT for grants.

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