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A biomass-templated Nb/ZnO nanocatalyst, synthesized by a mechanochemical-assisted and sacrificial template method, promotes catalytic conversion of levulinic acid to N-heterocycles under solvent-free conditions, exhibiting an outstanding catalytic performance in terms of conversion (94.5 %) and selectivity (97.4 %) towards one particular N-heterocycle compound. [Display omitted] • A biomass-templated Nb/ZnO nanocatalyst was synthesized. • Highly active catalyst for the conversion of levulinic acid to N -heterocycles. • Critical role of niobium was found for LA conversion. • Optimum 10 %Nb/ZnO exhibited high conversion (94.5 %) and selectivity (97.4 %). Herein, we report a Nb/ZnO nanocatalyst for the efficient conversion of levulinic acid, a platform molecule easily obtained from lignocellulosic biomass, to N -heterocycles under mild reaction conditions and the absence of solvent. Nb/ZnO nanocatalysts were synthesized by a mechanochemical-assisted and sacrificial template method, involving orange peel valorization toward nanostructured materials. Two different synthetic approaches, either one-step or two-step, as well as the amount of niobium deposited onto the ZnO support were investigated in order to obtain the nanocatalyst with the optimal catalytic properties. Results revealed the critical role of the niobium for LA conversion. The nanocatalyst containing 10 wt% of niobium and prepared following a two-step approach (10 %Nb/ZnO_2) exhibited the best catalytic performance with a 94.5% of conversion and 97.4% of selectivity towards one specific N -heterocycle compound. This work exemplifies the possibility of sustainable production of value-added compounds, in particular N-heterocycles, from biomass-derived feedstocks by playing with the design of improved catalysts. Importantly, this research area provides sustainable alternatives to the current chemical industry that is heavily dependent on fossil fuels. [ABSTRACT FROM AUTHOR]

5‐Hydroxymethylfurfural (HMF) has been identified as one of the most promising biomass‐based multi‐purpose platform molecules. Innovative protocols, namely electrocatalysis, photocatalysis, and microwave (MW)‐assisted chemistry, as well as continuous‐flow systems, add a new dimension and another promising toolbox for the oxidation of HMF in recent years. This Minireview deals with recent progress in the catalytic oxidation of HMF to 2,5‐furandicarboxylic acid (FDCA) and other intermediates using noble, non‐noble, and metal‐free systems deploying emerging protocols. Selective HMF downstream oxidation products could be obtained not only via common catalyst modifications, namely nature of the metal, preparative method, and the property of deployed support, but also by using innovative processes. [ABSTRACT FROM AUTHOR]

Furfural has been considered as one of the most promising platform molecules directly derived from biomass. The hydrogenation of furfural is one of the most versatile reactions to upgrade furanic components to biofuels. For instance, it can lead to plenty of downstream products, such as (tetrahydro)furfuryl alcohol, 2-methyl(tetrahydro)furan, lactones, levulinates, cyclopentanone(l), or diols, etc. The aim of this review is to discuss recent advances in the catalytic hydrogenation of furfural towards (tetrahydro)furfuryl alcohol and 2-methyl(tetrahydro)furan in terms of different non-noble metal and noble metal catalytic systems. Reaction mechanisms that are related to the different catalytic materials and reaction conditions are properly discussed. Selective hydrogenation of furfural could be modified not only by varying the types of catalyst (nature of metal, support, and preparation method) and reaction conditions, but also by altering the reaction regime, namely from batch to continuous flow. In any case, furfural catalytic hydrogenation is an open research line, which represents an attractive option for biomass valorization towards valuable chemicals and fuels. [ABSTRACT FROM AUTHOR]