Catalytic hydrofining of thermal dissolution-derived liquefied oil from Dongming lignite into cyclanes-rich liquid fuel over Co-CoNx@C650

Hydrofining of low-grade lignite liquefied oils into high-density liquid fuels is a critical pathway for their value-added utilization. However, abundant condensed aromatic rings (ARs) and O atoms in such crude oils pose significant challenges for secondary upgrading, particularly in achieving concurrent AR hydrogenation and hydrodeoxygenation in one-pot to produce alkyl cyclanes. In view of this, Co-CoN_x@C₆₅₀ was constructed by a cascade preparation strategy consisting of in-situ co-pyrolysis and NH₃ nitridation. It has highly dispersed Co-CoN_x dual-sites and carbon substrate with abundant defects/vacancies, and exhibits good performance in AR hydrogenation and hydrodeoxygenation. In addition, this catalyst can effectively activate H₂ and promote the synergistic transfer of H···H, ^δ+H···H^δ−, and H·. Good accessibility, cyclic stability, and renewability make it suitable for the hydrogenation of medium/large-sized molecules such as naphth-2-ol and aryl ethers into cyclanes. The liquefied oil (SP_TD) from Dongming lignite thermal dissolution in n-hexane is rich in aromatics (76.1 %), while refined oil (CHSP_TD) from catalytic hydrofining over Co-CoN_x@C₆₅₀ is rich in saturated hydrocarbons (91.7 %), especially alkyl cyclanes (69.8 %). The efficient conversion of aromatic-oxygenated moieties demonstrated by Co-CoN_x@C₆₅₀ provides a new solution for converting low-grade lignite liquefied oils into value-added cyclanes-rich liquid fuels.