Facilitating selective conversion of furfural to cyclopentanone via reducing availability of metallic nickel sites

Conversion of the biomass-derived furfural to cyclopentanone (CPO) involves multiple hydrogenation steps, in which not only the type but also the abundance of metallic sites might impact fates of the reaction intermediates and consequently selectivity of the products. In this study, we found that, during the hydrogenation, the carbonyl and the furan ring functionalities in furfural showed the different response to the number of nickel sites on Ni/SiO2 catalyst. The hydrogenation of the C = O in furfural could take place effectively with the nickel loading below 1 wt% to form firstly furfuryl alcohol (FA) and then to CPO with the selectivity as high as 98.2%. In comparison, the higher nickel loading favored the hydrogenation of the furan ring in furfural or FA to form tetrahydrofurfuryl alcohol (THFA), formation of which eliminated the chance for the formation of CPO. The hydrogenation of the carbonyl functionality and furan ring in furfural proceeded via distinct orientations of adsorption and the involvement of the varied number of metal sites. Controlling the number of exposed metallic nickel sites could thus tailor the selectivity of the products in hydrogenation of furfural.