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The catalytic hydrotreatment of humins, the solid byproduct produced from the conversion of C6 sugars (glucose, fructose) to 5-hydroxymethylfurfural (HMF), using supported Pd@zeolite (Beta, Y, and USY) catalysts with different amounts of Pd (i.e., 0.5, 1.0 and 1.5 wt%) was investigated under molecular hydrogen pressure. The highest conversion of humins (52.0%) was obtained on 1.5Pd@USY catalyst while the highest amount of humins oil (27.3%) was obtained in the presence of the 1Pd@Beta zeolite sample, at PH2 = 30 bars and T = 250 °C. The major compounds in the humins oil evidenced by GC-MS are alcohols, organic acids, ethers, and alkyl-phenolics. However, although all these classes of compounds are obtained regardless of the nature of the catalyst used, the composition of the mixture differs from one catalyst to another. Furanic compounds were not identified in the reaction products. A possible explanation may be related to their high reactivity under the reaction conditions, in the presence of the Pd-based catalysts these compounds lead to alkyl phenolics, important intermediates in the petrochemical industry.

The one-pot production of HMF from glucose was investigated in pure hot water and biphasic water/methylisobutylketone (MIBK) solvent using mesoporous Nb(0.02 and 0.05 mol%)-Beta zeolites obtained by a post synthesis methodology. The mesoporous Nb-Beta zeolites present residual framework Al-acid sites, extra-framework isolated Nb(V) and Nb2O5 pore-encapsulated clusters in which Nb(V)O-H exhibit moderate strength Bronsted acidity. After optimization, the dehydration of glucose onto the Nb-modified Beta-zeolites occurred with a selectivity of 84.3% in HMF for a glucose conversion of 97.4%. This result has been obtained in a biphasic water/MIBK solvent and in the presence of NaCl, at 180 °C, after 12 h.

The oxidation of 5-hydroxymethylfurfural (HMF) to valuable dicarboxylic acids has been investigated on magnetic-separable nanocatalysts in the search for selectivity enhancement. Cationic Ru(4 wt %)-Fe3O4@SiO2 catalyst led to 2,5-furandicarboxylic acid (FDCA), with a selectivity of 80.6% for HMF conversion of 92%. Replacing the deposited noble metal with a transitional oneand NaOH with n-butylamine ensured further advantages, such as the increase of HMF stability and the possibility to tune the selectivity for other valuable products. Thus, under similar reaction conditions, the Fe3O4@SiO2-CoOx(10 wt % CoOx) catalyst provided a selectivity to succinic acid (SA) of 92.7% for a HMF conversion of 78.6%, and the Fe3O4@SiO2-MnOx (10 wt % MnOx) catalyst led to 72% selectivity to maleic acid (MAc) for HMF conversion of 5%. However, the performances in this reaction have been improved (85% selectivity to MAc for HMF conversion of 35.6%) working with a metal-free catalyst (Fe3O4@SiO2-NH2), in which the −NH2 functi...

The oxidation of 5-hydroxymethylfurfural (HMF) to 2,5-furandicarboxylic acid (FDCA) has been investigated on multi-functional magnetic nano-composite catalysts (10M@xNb@MNP, where M = CoOx, MnOx or FeOx, "10" - 10wt% and x = Si/Nb ratio of 50 and 22) combining Nb-MCM-41 and Mn, Co and Fe oxides as a shell of a magnetic nanoparticles core. These catalysts were exhaustively characterized by several techniques such as XRD, adsorption-desorption of liquid nitrogen at 77K, CO2- and NH3-TPD, DRIFT, XPS, SEM-EDX, ICP-OES and ToF-SIMS. The new composite catalysts produced FDCA with a selectivity of 96.5 % for a XHMF = 96.9 % (10Co@22Nb@MNP). A synergetic effect between MOx and Nb species in the activation of t-BuOOH and oxidation of HMF has been identified. The new developed catalysts do not require the presence of a base in the homogeneous phase and combine unique oxidation properties with practical separation advantages.

The one-pot production of succinic acid from glucose was investigated in pure hot water as solvent using Nb (0.02 and 0.05 moles%)-Beta zeolites obtained by a post-synthesis methodology. Structurally, they are comprised of residual framework Al-acid sites, extra-framework isolated Nb (V) and Nb2O5 pore-encapsulated clusters. The Nb-modified Beta-zeolites acted as bi-functional catalysts in which glucose is dehydrated to levulinic acid (LA) which, further, suffers an oxidation process to succinic acid (SA). After the optimization of the reaction conditions, that is, at 180 °C, 18 bar O2, and 12 h reaction time, the oxidation of glucose occurred with a selectivity to succinic acid as high as 84% for a total conversion.