Abstract: To overcome the limitations of active component aggregation and uncontrolled facet exposure typical of impregnation methods, we report a chloride-mediated engineering strategy to precisely tailor the morphology and electronic structure of Fe/MgO-CaO catalysts. Structural characterizations reveal that the gas-etching effect during NH?Cl pyrolysis creates a porous architecture. Acting as a morphological modifier, NH?Cl induces the directional growth of MgO-CaO from disordered sheets into a rod-like structure with preferentially exposed (200) facets. At the microstructural level, Cl- doping strengthens the interaction between Fe species and the MgO lattice. This effectively inhibits the agglomeration of active components and promotes the formation of a highly dispersed Mg-Fe-O solid solution, while generating uniformly distributed Lewis acid sites on the catalyst surface. Consequently, the unique rod-like solid solution exhibits excellent structural stability during the catalytic reaction, successfully preventing framework collapse. Consequently, the optimized catalyst (Fe-Cl = 1.00) boosted glycerol conversion from 60 % to 90 % relative to the Cl- free benchmark. This chloride-mediated engineering strategy provides a blueprint for valorizing natural minerals and rationally designing robust non-noble metal catalysts.

Key words: Glycerol; Transition metal iron, Chloride, MgO/CaO, 1,2-Propanediol