Topological iron silicide with H* intermediate modulated surface for efficient electrocatalytic hydrogenation of nitrobenzene in neutral medium

Electrocatalytic hydrogenation of nitrobenzene (Ph-NO₂) reaction (EHNR) has been considered as a potential alternative to the traditional thermocatalytic process in the production of high-value aniline (Ph-NH₂). However, due to the absence of robust catalyst and low surface H* coverage, the EHNR faces the challenges of undesired performance and indetermined mechanism. Herein, we construct a type of noble-metal free topological FeSi (M-FeSi) materials through a solvent-free microwave strategy for efficient EHNR in neutral medium. Impressively, benefiting from abundant active H* intermediates on the surface of M-FeSi catalyst, the topological M-FeSi catalyst exhibits 99.7% conversion of Ph-NO₂ and 93.8% yield of Ph-NH₂ after 200 C in neutral medium, which are superior to previous candidates and FeSi catalyst synthesized via the traditional arc-melting method under same conditions. Besides, theoretical calculations validate that high surface H* coverage over M-FeSi catalyst is conducive to switching the rate-determining step from Ph-NO₂* → Ph-NO* to Ph-NO* → Ph-NHOH*, and thus decreasing the total energy barrier of electrocatalytic Ph-NH₂ production.     

Efficient reduction of nitroarenes using supercritical alcohols as a source of hydrogen in flow-type reactor in the presence of alumina

Reduction of nitroarenes using supercritical alcohols as a source of hydrogen was studied in a flow reactor in the presence of alumina at temperatures 515–615 K and residence times not exceeding 6 min. In the reaction of nitrobenzene reduction by 4-methylpentan-2-ol in supercritical (sc) CO₂, the selectivity for aniline reached 95% with a conversion of 71%. If methanol was used as the reducing agent, the main reaction product was N,N-dimethylaniline. It was shown that the use of scCO₂ co-solvent had a significant impact on the course of the reduction process including secondary and side reactions. The conditions for the reduction of halogenated nitroarenes into respective amines with high conversion and nearly 100% selectivity almost without dehalogenation were found.