Novel two-dimensional Ti₃C₂T_x MXene-supported Ni-M (M = Pd, Pt, Ru): A remarkable catalyst for efficient HDO of guaiacol under hydrothermal conditions: Performance, mechanism and kinetic studies

Currently, traditional hydrodeoxygenation (HDO) catalysts have various shortcomings such as low activity levels and vulnerability to deactivation. Therefore, a series of MXene-supported Ni-M (M = Pd, Pt, Ru) bimetallic catalysts were designed and prepared. The above catalysts were also comprehensively characterized using XRD, BET, H₂-TPR, NH₃-TPD, XPS, SEM and TEM methods. Moreover, due to the largest particular specific surface area, moderate amount of acid sites and the strongest three-electron transfer channels between support and active metals of Ni-Pd/MXene catalyst, it exhibited the superior catalytic performance to achieve 100 % guaiacol conversion and 35.15 % highest overall yields of HDO products (Y_HDO) under the optimal reaction conditions (at 340 °C for 8 h, utilizing in-situ hydrogen source: formic acid). Furthermore, a detailed discussion on the main reaction pathways and mechanism of guaiacol HDO catalyzed by Ni-Pd/MXene was provided, an unique bimetallic synergistic “relay catalytic” theory has been proposed. Kinetic studies revealed that phenol, one of the main HDO products, is primarily generated via guaiacol demethoxylation, while catechol dehydroxylation to phenol acts as the rate-determining step. This work introduces a new strategy for the development of HDO catalysts.