Selective conversion of 5-hydroxymethylfurfural (HMF) to liquid fuels is an important step in the valorization of carbohydrates. Although not paid much attention to in the scientific community, we discovered an enormous impact of the HMF purity on the product selectivity during its hydroconversion in the presence of Ru/C. The presence of dimethyl sulfoxide (DMSO) showed the most dramatic effect on the aromatic hydrogenation activity, with almost full selectivity for either 2,5dimethylfuran (DMF) or 2,5-dimethyltetrahydrofuran (DMTHF). The sulfur to surface ruthenium molar ratio predicts the selectivity outcome. A similar selective poisoning effect of DMSO was observed while using 2,5-bis(hydroxymethyl)furan (BHMF) as feedstock. These findings provide an approach to modify the selectivity of HMF conversion using the Ru/C catalyst and draw attention to the utmost importance of biobased reagent purity for catalytic studies to avoid erroneous conclusions about catalyst properties.

BHMF), 2,5-bishydroxymethyltetrahydrofuran (BHMTHF), and 2,5-dimethyltetrahydrofuran (DMTHF). In addition, multifunctional catalytic systems that enable a tunable production of various HMF derived intermediates are discussed. Within this chemistry, the surprising impact of HMF purity on the catalytic performance, such as selectivity and activity, during its upgrading is highlighted. Lastly, the remaining challenges in the field of HMF hydroconversion to the mentioned chemicals are summarized and discussed, taking into account the knowledge gain of catalyst properties and feedstock purity.

The transformation of 5-hydroxymethylfurfural (HMF) into ring-saturated furanics is a vital step in carbohydrate valorization. In this work, we report on the remarkable catalyst poisoning effect of numerous sulfur species for HMF hydroconversion. The presence of minor amounts of dimethyl sulfoxide (DMSO) affects ring-saturated product selectivity for the metal-catalyzed reactions using molecular hydrogen, whereas it fully deactivates catalytic transfer hydrogenation (CTH) in 2-propanol. The degree of poisoning correlates with the thermodynamic favorability of the metal sulfide formation. Reduced sulfur species (sulfide or thiol) are the ultimate metal poisoning agent. Their easy formation from more oxidized sulfur compounds explains the observed poisoning effect for such species. Here, the metal’s oxophilicity determines the catalysts’ behavior in the presence of oxidized sulfur species by forming (or not) poisoning sulfur–metal interactions. To overcome the sulfur poisoning, we propose DMSO removal with organic solvent extraction and catalyst oxidation post-treatment. These findings pinpoint the crucial, though overlooked, role of the biobased HMF purity for reductive catalytic studies. We provide a deeper understanding of the noble metal poisoning by sulfur from different origins and oxidation states that may be present during HMF hydroconversion.

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