Uranium-Doped Zinc, Copper, and Nickel Oxides for Enhanced Catalytic Conversion of Furfural to Furfuryl Alcohol: A Relativistic DFT Study

Abstract

Transition metal oxides (TMOs) and actinide ones (AnOs) have been widely applied in catalytic reactions due to their excellent physicochemical properties. However, the reaction pathway and mechanism, especially involving TM–An heterometallic centers, remain underexplored. In this respect, relativistic density functional theory (DFT) was used to examine uranium-doped zinc, copper, and nickel oxides for their catalytic activity toward the conversion of furfural to furfuryl alcohol. A comparison was made with their undoped TMOs. It was found that the three TMOs were capable of catalyzing the reaction, where the free energies of adsorption, hydrogenation, and desorption fell between −33.93 and 45.00 kJ/mol. The uranium doping extremely strengthened the adsorption of CuO-U and NiO-U toward furfural, making hydrogenation or desorption much harder. Intriguingly, ZnO-U showed the best catalytic performance among all six catalyst candidates, as its three reaction energies were very small (−10.54–8.12 kJ/mol). The reaction process and mechanism were further addressed in terms of the geometrical, bonding, charge, and electronic properties.

Mechanism Insights into the Decarbonylation of Furfural to Furan over Ni/MgO: A Molecular Simulation Study

“…In the first reaction stage, the H atom on the aldehyde group is detached from FF and the activation energy barrier ( E barrier1 ) is 195.26 kJ/mol, which is the RDS of the whole process of FF decarbonylation. Intermediate (C 4 H 3 O)­CO is adsorbed at the Ni site with the C-terminus of the branched chain, and this adsorption pattern is consistent with the adsorption of (C 4 H 3 O)­CO on the surface of Zn, Cu, and Ni oxide catalysts in the study of Li et al Meanwhile, the H atom is adsorbed in the Mg site at a distance of 1.335 Å. In the second reaction stage, the C–C bond on the branched chain is interrupted and a new C–H bond is formed to produce furan, with an activation energy barrier ( E barrier2 ) of 44.66 kJ/mol.…”