ZnO-Carbon-Nanotube Composite Supported Nickel Catalysts for Selective Conversion of Cellulose into Vicinal Diols

Abstract

A ZnO-nanolayer-coated carbon nanotube (CNT) composite (ZnO–CNT) was employed as a support to immobilise Ni catalysts. Well-mixed oxides, formed as a result of enhanced interfaces between the two oxides on CNTs, resulted in the formation of Ni–Zn alloys in reduced catalysts. The Ni/ZnO–CNT catalyst exhibited much higher yields of vicinal diols, for example, ethylene glycol and 1,2-propylene glycol, from the conversion of cellulose than the reference Ni/CNT catalyst. A plausible reaction network on the Ni/ZnO–CNT catalyst has been proposed. Moreover, the effects of Ni loading and catalyst reduction temperature on the catalytic performance were probed, and the relationship between the catalyst structure and the yields of vicinal diols was correlated. The Ni-rich alloy, relative to the Zn-rich alloy, was suggested as the dominating active phase for the selective conversion of cellulose into vicinal diols. This might shed new light on the design and optimisation of Ni-based catalysts for the catalytic conversion of cellulose with the Ni–Zn interaction.