Bimetallic SBA-15 Catalysts for Selective Steam Cracking of LDPE into Light Hydrocarbons and Hydrogen

The growing accumulation of plastic waste in landfills, particularly low-density polyethylene (LDPE), poses severe environmental challenges due to its resistance to mechanical recycling and natural degradation. This study investigates bimetallic SBA-15-supported catalysts for enhancing steam cracking of LDPE to produce C 1 –C 4 hydrocarbons and hydrogen, under steam-assisted conditions. Mesoporous SBA-15-supported FeNi and CuNi catalysts were compared with monometallic Ni/SBA-15 and Ni/Silica. BET, XRD, and SEM characterization showed the pure SBA-15 had a surface area of 1009.6 m 2 /g, which decreased after metal loading (10 wt % Ni with 5 wt % Fe or Cu) to 620.8, 553.4, and 544.8 m 2 /g, respectively, while retaining high metal dispersion. Among the catalysts, FeNi/SBA-15 achieved the highest yields of light hydrocarbons (19.55 mol/kg LDPE) and hydrogen (5.02 mol/kg LDPE) at 850 °C. This was attributed to synergistic Fe–Ni effects, enhancing steam reforming, while nickel promoted dehydrogenation. Overall, the bimetallic catalysts effectively regulated the cracking process with notably higher yields of ethylene and propylene compared to Ni/SBA-15 and the reference Ni/Silica catalyst. These findings underscore the potential of engineered bimetallic catalysts for the sustainable valorization of plastic waste, supporting circular economy initiatives and advancing cleaner thermochemical recycling technologies.