Two-step cascade degradation of Dongming lignite over Mo/N co-doped ZIF-67-based Co-Mo15@NC

A novel ZIF-67-based Co-Mo bimetallic synergistic catalyst was prepared via Mo/N co-doping in-situ pyrolysis strategy and used in the cascade conversion system of hydrocracking (H₂ activation) and ethanolysis (solvent activation) of Dongming lignite. Co-Mo₁₅@NC, rich in vacancies/defects, can differentially activate H₂ and ethanol, promoting the selective conversion of lignite-derived aryl ethers into high-yield arenes or aromatic monomers. Comprehensive evaluation indicates that this catalyst exhibits excellent > C-O- cleavage activity and cyclic stability, and is easy to magnetic recovery. Analysis of intermediates and products shows that hydrocracking system involves the synergistic transfer of H⁺, H·, and asymmetric diatomic active hydrogen (^δ+H···H^δ-), while ethanolysis system involves the synergistic transfer of H⁺, H·, C₂H₅⁺, and C₂H₅O·. Hydrocracking-derived oil (SP_1C) from first-stage is rich in alkanes and polycyclic arenes, with the total content of hydrocarbons increasing from 67.7 to 78.1 %, while ethanolysis-derived oil (SP_2C) from second-stage is rich in alkanols, arenols, and esters, with the total content of O-containing compounds increasing from 66.7 to 90.3 %. Two types of value-added oils, i.e., hydrocarbon-rich and O-rich oils, can be obtained by the two-step cascade degradation strategy based on H₂ and ethanol activation.