Catalytic cracking of waste cooking oil over activated carbon supported monometallic, bimetallic and trimetallic oxides

Converting waste cooking oil into biofuels, which are sustainable and renewable, is a viable path for the power and transportation sectors. This study investigated the performance of trimetallic oxide catalysts in catalytic cracking of waste cooking oil into renewable hydrocarbons. The activities have been compared to that of mono and bimetallic oxide catalysts. Metals were incorporated into activated carbon (AC) to prepare monometallic oxides, bimetallic oxides and trimetallic oxides, with a total metal loading of 10 wt%. The reactions were conducted in a batch reactor at 400^oC for one hour. The catalysts were characterized by N₂ physisorption, XRD, SEM-EDX, and TPD-NH₃/CO₂. This study showed that using trimetallic oxides lead to higher liquid yield and lower coke formation in the reaction, compared to both mono- and bimetallic oxide catalysts. Particularly, using NiO-Fe₃O₄-ZnO/AC gave the highest liquid yield (> 90 wt%) with merely 0.05 wt% coke formation. The liquid product predominantly comprised hydrocarbons reaching concentrations as high as 52.44%. NiO-Fe₃O₄-ZnO/AC possessed 836 m²/g BET surface area, 0.43 cm³/g pore volume and 1.92 nm pore diameter with 20,114 µmol/g strong acidity and 85 µmol/g strong basicity.