Surface Synergetic Effects of Ni-ReO_x for Promoting the Mild Hydrogenation of Furfural to Tetrahydrofurfuryl Alcohol

Ni-ReO_x bimetallic catalysts (Ni-ReO_x/TiO₂) were prepared through a successive impregnation method, which is extremely active in furfural (FAL) hydrogenation to tetrahydrofurfuryl alcohol (THFOL) under mild reaction conditions. For instance, high FAL initial reaction rate (439.4 mmol/g_-Ni/h) and THFOL formation rate (80.4 mmol/g_-Ni/h) were achieved over Ni-5ReO_x/TiO₂, which are 13.2 and 6.6 times higher than those of Ni/TiO₂, respectively. The unique catalyst reactivity derives from rich Lewis acidic ReO_x and intimate electron interaction of ReO_x with Ni NPs. Kinetic studies reveal that ReO_x decoration decreases the activation barrier of −C═O hydrogenation other than the furan ring. Mechanism studies show that ReO_x has a good affinity for C═O and H₂ and favors hydrogen spillover and C═O bond activation on Ni, thus reinforcing the synergistic effect of Ni and ReO_x. This catalyst is versatile for various furan aldehydes and is relatively stable for 5 times recycling, showing relative potential for industrial application. © 2023 American Chemical Society.