Alloying cobalt in Co–Fe–Al catalyst for achieving the selective conversion of furfural to cyclopentanone

Abstract

Production of cyclopentanone (CPO) from biomass-derived furfural is attractive but challenging, as deep hydrogenation or ring-opening of furan ring in furfural over Co-based catalysts hinders the formation of the targeting products. In this study, alloying Co with Fe species in Co–Fe–Al catalysts is proposed for selective conversion of furfural to CPO in water. The formation of CoFe alloy in Co–Fe–Al catalyst weakened the interaction between Co species and the alumina carrier, lowered the adsorption/activation of H2, suppressed the formation of especially Brønsted acidic sites, facilitated the electron transfer from Co0 to Fe species, increased the activation energy for hydrogenation of furfural (from 17.2 kJ mol−1 over Co–Al to 33.4 kJ mol−1 over 1.5Co-1.5Fe-1.0Al), and weakened the adsorption of CC and C–O–C functionalities in furan ring of furfuryl alcohol (FA) on metallic sites. These factors together suppressed deep hydrogenation of furan ring in FA or ring-opening of FA to diols, producing CPO and CPL with total yield of 91.5%, which was attributed to the synergy between hydrogenation and Brønsted acidic sites. In addition, the presence of Fe in Co–Fe–Al catalysts also enhanced the structural stability of Co species, preventing the phase transformation and aggregation of Co species, and rendering the catalyst with superior reusability.