Catalytic hydrotreatment of Kraft lignin into liquid fuels over porous ZnCoOx nanoplates

Abstract

The effective utilization of Kraft lignin is being increasingly recognized as a crucial pathway for realizing environmental sustainability and energy goals. Herein, we prepared a novel ZnCoOx nanoplate catalyst to effectively depolymerize Kraft lignin into liquid fuels in a mixed solution of 1, 4-dioxane and methanol. Kraft lignin could be converted into 82% yield of the liquid product under relatively mild conditions (300 °C, 2 MPa H2), and 71% of the liquid product was soluble in petroleum ether, which is composed mainly of monomers and dimers. The catalysts were characterized by a series of methods including BET, SEM, XRD, NH3-TPD, and H2-TPR. A meticulous study on ZnCoOx nanoplates revealed that the synergistic effect among Lewis acid, hydrogen activation functionalities, and catalyst structure was responsible for the depolymerization of lignin. This work demonstrates the significant potential for the direct, simple, and energy-efficient and the realization of an industrially applicable preparation of lignin-derived liquid fuels from Kraft lignin.