Authors: Lopez-Aguado, C; Paniagua, M; Iglesias, J; Morales, G; Garcia-Fierro, JL; Melero, JA

Article; Proceedings Paper.
Catal. Today. vol: 304. page: 0920-5861.
Date: APR 15. 2018.
Doi: 10.1016/j.cattod.2017.08.031.

Abstract:
A series of bifunctional USY zeolite catalysts with different Al/Zr ratios were synthesised. The incorporation of Zr into the structure was accomplished after partial dealumination of H-USY. Structural and spectroscopic characterization confirmed the preservation of the zeolite network as well as the isolated incorporation of Zr atoms in Al vacancies, with no evidence of large zirconia domains. The catalytic evaluation in the transformation of xylose in 2-propanol allowed to obtain interesting mixtures of bio-products, and to identify the presence of two competitive routes: the formation of GVL following alternating acid-driven and hydrogen-transfer (MPV) steps, and the retro-aldol condensation of xylose. The extent of each of these two competing reaction cascades is strongly dependent on the Zr loading. Thus, the catalyst with the lowest Al/ Zr ratio favours the xylose retro-aldol condensation. When considering furfural as starting substrate, only products involved in the cascade to GVL are obtained. In this case, the incorporation of Zr in the catalyst favoured the MPV reactions, enhancing furfural conversion rate. Thus, increasing concentrations of products coming from the reduction of furfural-furfuryl alcohol, furfuryl 2-propyl ether, lactones-, were detected over Zr-USY samples, with the Zr-USY-3 yielding 13.5% of the final product, GVL. The catalysts are reusable after thermal regeneration at 550 degrees C..