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It has previously been reported that the use of microwave heating, together with the presence of co-solvents, improves the efficiency of furfural production from biomass. Solid acid catalysts can be a good alternative to mineral acids, since they can prevent corrosion and can be reused. However, the formation of humines should be minimized. Several delaminated and fluorinated hectorites, with different types and strengths of acid sites, were synthesized and tested as catalysts for the production of furfural from commercial xylose and from an acid biomass extract of almond shells. A new methodology was developed to prepare crystalline fluorohectorite at 800 °C in just 3 h. The presence of F significantly increased the acidity strength in the protonated fluorohectorite (H-FH) taking into account its high ammonia desorption temperature (721 °C). Additionally, this sample had fourteen times higher total acidity by m2 than the reference H-βeta acid catalyst. H-FH was the most efficient catalyst at short reaction times (1 h) for the transformation of xylose to furfural under microwaves using toluene as co-solvent, regardless of whether the xylose was commercial (20% furfural yield) or an extract of almond shells (60% furfural yield). However, the acidity of the extract affected the fluorohectorite structure and composition.

Several Ni, Cu and Ni-Cu catalysts supported on mesoporous hectorite were prepared, characterized and tested for the hydrogenation of commercial furfural to obtain tetrahydrofurfuryl alcohol (THFA). The highest selectivity to THFA (95 %) for a total conversion was achieved with the Ni-Cu catalyst prepared with a Ni:Cu molar ratio of 1:1 after 4¿h of reaction. This can be explained by the formation of NiCu alloy in high amounts for this sample (88 %), as detected by XRD. The lower selectivity to THFA obtained with other bimetallic catalysts prepared with Ni:Cu molar ratios of 6:1 and 1:6 were attributed to the lower percentage of NiCu alloy together with the lowest Ni richness of the NiCu alloy. Additionally, the best catalyst resulted in a yield to THFA of 90 %, in the toluene phase, and 80 % in the aqueous neutralized phase, when using a biomass extract of furfural obtained from almond shells instead of commercial furfural. After several reuses of the catalyst employed in the toluene phase, some decrease of THFA was observed due to the increase of the crystallite size of the Cu phase, as observed by XRD, that should decorate the active NiCu alloy particles. Peer Reviewed