Selective hydrogenation of furfural to furfuryl alcohol without external hydrogen over N-doped carbon confined Co catalysts

Abstract

Non-noble metal catalyzed transfer hydrogenation of biomass using biomass-derived formic acid (FA) as hydrogen source is one of promising strategies for relieving fossil energy crisis. Since acidic FA would destroy and deactivate naked active sites, developing heterogeneous catalysts with stabilized structure and activity that are qualified in harsh conditions is highly desirable but challenging. Herein, mesoporous N-doped carbon encapsulated Co catalysts (Co-N-C) are synthesized through a facile carbonization of Co(phen)2(OAc)2 with nano-MgO as porogen agent. After acid treatment, the optimized Co-N-C-700 (pyrolyzed at 700 °C) could afford full furfural (FAL) conversion as well as >99% furfuryl alcohol (FOL) selectivity with only 3.5 equiv. FA at 150 °C for 6 h, exhibiting much superior performance than commercial Pd-, Pt- and Ru-based catalysts. Using molecular H2 as hydrogen source not only affords low conversion but also leads to over-hydrogenation of FOL and generation of furfuryl formate (FF). This catalyst is very stable in acidic FA and could be recycled 5 times without deactivation or leaching. Co-N-C-700 is also capable for gram-scale transfer hydrogenation of FAL and is versatile for other aldehydes with >90% yield of desired products. This work could promote the application of encapsulated Co-based catalysts for selective transformation of biomass in chemical industry.