Search

Furfural is regarded as one of the most promising bio-based feedstocks in the bio-refinery industry. Selective hydrogenation of the carbonyl bond in furfural plays a vital role in its conversion to downstream products. Electrochemical hydrogenation (ECH) method provides a green and sustainable way for this reaction. Yet, it still suffers from harsh pH conditions and low selectivity for highly reduced products, such as 2-methylfuran. In this study, high faradaic efficiencies of over 90% for furfuryl alcohol and 60% for 2-methylfuran were obtained in a near-neutral environment (pH = 5) at −0.75 V and −0.90 V vs. the reversible hydrogen electrode, respectively. The key to this success is the integration of single atom copper active sites and the oxophilic phosphorus dopants in a single catalyst. Single atom Cu sites are found to be the active centers for this reaction and decreasing the size of Cu sites to a single atom enhances the efficiencies of the ECH reactions by suppressing the competing hydrogen evolution reaction. Phosphorus doping facilitates furfural hydrogenation to 2-methylfuran via a sequential two-step reduction process. This study opens up possibilities for the selective electrochemical hydrogenation of furfural to 2-methylfuran under mild conditions.

Nitrogen-doped carbon-supported cobalt–molybdenum bimetallic catalysts (abbreviated as Co–Mo/NC) are active for the hydrodeoxygenation of sulfoxides to sulfides under mild conditions (25–80 °C and 10 bar H2), which represents the first example of the use of heterogeneous non-noble metal catalysts for this transformation. MoO3 with Lewis acid sites assists the hydrodeoxygenation of sulfoxides into sulfides by hydrogen over cobalt nanoparticles.

The development of new strategies for metal-free promoted reactions has recently received great interest from chemists because these processes benefit from the use of inexpensive catalysts and from avoidance of contamination of the desired products by the metal catalysts. In this study, a method for HNO3-promoted oxidation of biomass-derived 5-hydroxymethylfurfural (HMF) to 2,5-diformylfuran (DFF) was developed in the presence of nitrogen-doped carbon materials using molecular oxygen as the terminal oxidant under mild reaction conditions. The catalytic activity of the nitrogen-doped carbon materials was discovered to greatly increase with increasing pyrolysis temperature; it also depended on both the type of nitrogen atoms in the catalyst and the surface area of the catalyst. The NC-950 catalyst demonstrated unprecedented catalytic activity towards the oxidation of HMF to DFF. Several reaction parameters, such as the reaction solvent, the reaction temperature, the amount of HNO3, the catalyst loading and the oxygen pressure, have been investigated. The highest DFF yield of 95.1% was attained with full HMF conversion after 14 h at 100 °C under 10 bar oxygen pressure in the presence of a catalytic amount of HNO3. Control experiments indicated that the oxidation of HMF was initially promoted by HNO3, and O2 acted as a secondary oxidant for HNO3 recovery. In particular, the NC-950 catalyst had remarkable reusability without significant losses in its activity and selectivity after six consecutive usages.