Selective Catalysis for the Reductive Amination of Furfural Towards Furfurylamine by the Graphene-Co-Shelled Cobalt Nanoparticles

Amines with functional groups are widely used in the manufacture of pharmaceuticals, agricultural chemicals, polymers, and surfactants; so far, amines are mostly produced via petrochemical routes, which motivates the sustainable production of amines from renewable resources, such as biomass. Unfortunately, the reductive amination of biomass-derived platforms is now suffering from challenges, e.g. poor selectivity and carbon balances, because of the restriction of homogenous catalyst. For this reason, we developed an eco-friendly, simplified, and highly effective procedure for the preparation of non-toxic heterogeneous catalyst based on the earth-abundant metals (i.e., cobalt), whose catalytic activity on furfural or other biomass-derived platforms were proved to be broadly available. The corresponding conversion rate and few of side products were also determined so as to optimized the reaction conditions, suggesting that the prepared cobalt-supported catalyst enables easy substitution of –NH₂ moiety towards functionalized and structurally diverse molecules, even under very mild industrially viable and scalable conditions. More surprisingly, the cobalt-supported catalyst could also be expediently recycled by magnetic bar and still remained the excellent catalytic activity after reusing up to eight times; on another hands, the gram-scale reductive amination catalyzed by the same catalyst exhibited the similar yield of target products in comparison to its smaller scale, which was comparable to the reported heterogeneous noble-based catalysts. And also, results from a series of analytic technologies involving XRD, XPS, TEM/Mapping and in-suit FTIR revealed that the structural features of catalyst are closely in relation to its catalytic mechanisms; in simple terms, the outer graphitic shell is activated by the electronic interaction between the inner metallic nanoparticles and the carbon layer as well as the induced charge redistribution. In conclusion, this newly developed catalysts enable the synthesis of amines from biomass-derived platforms with satisfied selectivity and carbon balance, providing a cost-effective and sustainable access to the widely application of reductive amination.