Metal Catalyst-Dependent Poisoning Effect of Organic Sulfur Species for the Hydroconversion of 5-Hydroxymethylfurfural

Abstract

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.