Interfacial oxygen vacancies and Cu-Ni bimetallic sites synergistically enhance the catalytic hydroconversion of soluble portion from lignite thermal dissolution

Mild thermal dissolution is an effective method for the clean, low-carbon conversion of lignite. However, the resulting products still contain numerous oxygen-bridged bonds and heavy molecular compounds, requiring further upgrading to serve as suitable feedstocks for fuels and chemicals. In this study, a supported Cu-Ni bimetallic catalyst was synthesized via a co-precipitation method and applied to the catalytic hydroconversion (CHC) of thermal dissolution portions from Zhaotong lignite (ZT) and lignite-related model compounds (LRMCs). Catalyst characterization revealed that metal particles were uniformly dispersed on the surface of the Cu-Ni/CoOx-CeO 2 catalyst, along with the formation of defect sites. The CoOx-CeO 2 support promoted surface oxygen vacancy formation. Furthermore, the incorporation of Ni altered the local coordination environment of Cu species through multicomponent interactions. The synergy between interfacial oxygen vacancies and Cu-Ni bimetallic sites significantly enhanced catalytic activity. Tests with LRMCs indicated that the Cu-Ni/CoOx-CeO 2 catalyst selectively cleaves C-O ether bonds under mild conditions, exhibiting both high selectivity and strong hydrogenation activity in the CHC of phenolic compounds. The catalyst also effectively promoted the CHC of macromolecular species in the soluble portion from ZT thermal dissolution, thereby converting phenolic compounds into cycloalkanol. These finding provides valuable insights for developing staged conversion routes and achieving value-added utilization of lignite.