Alloying nickel with phosphorus to switch the selective conversion of furfural from furans to cyclopentanones or 1,4-pentanediol

Abstract

Metallic nickel species generally show high activity for hydrogenation of C=C in furfural, eliminating the formation of furfuryl alcohol (FA) that is the precursor for production of value-added chemical such as 1,4-pentanediol (1,4-PeD) and cyclopentanone (CPO). To tackle this issue, alloying of nickel in Ni/SiO2 catalyst with phosphorus for suppressing the excessive hydrogenation activity was conducted in this study. The results showed that the increase of phosphorus loading led to the transition of the alloy phase from Ni12P5 to Ni3P and then to Ni2P, which was also accompanied with the increased abundance and strength of Lewis acid sites but not the Brønsted acid sites. The acidic sites constructed by P-O structure (phosphates) can effectively adsorb C-O of furfural, preventing the transformation of the adsorption to vertical configuration and facilitated the ring-opening and rearrangement of furfural to CPO and 1.4-PeD. Selective conversion of furfural to 1,4-PeD with the yield of 85.3 % could be achieved over Ni-10 %P/SiO2 catalyst but only at 150 °C with the aid of the Lewis acidic sites while not the Brønsted acid sites. The conversion of furfural at 170 °C over Ni-15 %P/SiO2 catalyst activated Brønsted acid sites and hydrogenation sites for catalyzing formation of CPO and cyclopentanol (CPL) with sum yield of up to 93.6 %. The selective conversion of furfural to either 1,4-PeD or CPO thus could be flexibly switched by tailoring activity of the acid sites and hydrogenation sites.