Ni–Co/ZrO₂ (NCZ) nano-structure catalysts prepared by the hydrothermal method (NCZ-hyd) and conventional impregnation (NCZ-imp) method. The comparative catalytic activity and coke resistance for each prepared catalyst were examined in steam reforming of phenol and polyethylene terephthalate (PET) plastic waste. The Physico-chemical catalysts properties were characterized by N₂-adsorption, XRD, FTIR, TEM, SEM, EDX, H2-TPR, CO2-TPD, and TGA. The effects of preparation methods of NCZ nano-structure catalyst on the catalytic performances in PET-phenol steam reforming were investigated. The NCZ-hyd nanostructure catalyst exposed more outstanding catalytic activity and more excellent coke resistance in comparison with the NCZ-imp. The experimental findings exhibited that catalyst synthesized by hydrothermal method were uniform with the size of 8.8 nm, while NCZ particles prepared by …