To address the bottlenecks of difficult recovery of powder catalysts and unsatisfactory directional upgrading performance of volatiles in coal catalytic pyrolysis, this work develops recyclable MgFe₂O₄-based magnetic core-shell catalysts and elucidates the structure-activity relationship governing volatile upgrading during coal pyrolysis. MgFe₂O₄ with different morphologies were synthesized by regulating template agents and hydrothermal reaction conditions. MgFe₂O₄@HZSM-5 zeolite-type core-shell catalysts are fabricated via in-situ hydrothermal coating method, and Mo active species are introduced through in‑situ doping. The catalysts were comprehensively characterized by including SEM, XRD, BET, NH₃-TPD and XPS are performed to analyze the morphology, crystal phase, pore structure, acidity and surface electronic state of catalysts, and the catalytic pyrolysis performance is evaluated in a fixed-bed reactor with Huangling coal as feedstock. The results show that spherical MgFe₂O₄ synthesized with citric acid has high crystallinity and regular morphology, which is suitable as the magnetic core of core-shell catalysts. XPS results verify that Fe species within the MgFe₂O₄ spinel exist as co‑existing Fe²⁺/Fe³⁺ mixed‑valence states, accompanied by abundant surface oxygen vacancies. These redox sites synergized with oxygen vacancies activate gaseous water and promote decarboxylation of oxygen‑containing volatiles, mediating hydrogen transfer reactions and endowing the magnetic core with hydrogen‑supply capacity alongside its inherent magnetic separability. For the in‑situ Mo‑doped MgFe₂O₄@HZSM‑5 catalyst, Mo species are highly dispersed in the form of Mo⁵⁺/Mo⁶⁺ mixed‑valence states, which generates abundant Lewis‑acid sites and builds a bifunctional catalytic system together with the intrinsic Brønsted‑acid sites of zeolite. Under the action of this catalyst, the tar yield is maintained at 14.15 wt.%, and the BTEXN content in tar reaches 8.52% with phenolic compounds significantly reduced. The Mo-modified magnetic core–shell catalyst operates via a hierarchical synergistic mechanism of "core hydrogen supply–shell shape-selective catalysis–metal collaborative upgrading": the magnetic core delivers hydrogen‑transfer capability together with magnetic separability, the HZSM-5 shell provides a shape-selective aromatization environment, and the Mo active sites synergistically promote phenolic deoxygenation and light aromatic formation. This work presents a catalytic material that combines high activity with recyclability for the pyrolysis upgrading of low-rank coal.

MgFe2O4; magnetic core-shell catalyst; catalytic pyrolysis; low-rank coal; light aromatic;