NiW catalysts supported on natural Zeolite–Alumina composites for hydrodeoxygenation of palm fatty acid distillate to green diesel

Natural zeolite-alumina composites were employed as supports for NiW catalysts to enhance the hydrodeoxygenation (HDO) of palm fatty acid distillate (PFAD) into green diesel. This study investigates the effect of the zeolite-to-alumina support ratio on the physicochemical properties and catalytic performance of the resulting NiW catalysts. The composite supports were synthesized via a sol-gel method, followed by active metal deposition using wet impregnation. Characterization results revealed that increasing the alumina content significantly enlarged the specific surface area and total acidity, which consequently modulated the acid site density of the catalysts. Catalytic evaluations demonstrated that the support composition strongly influenced liquid product yield and hydrocarbon distribution while suppressing cracking at higher alumina content. Among the investigated compositions, NiW/Z 50 A 50 achieved the highest liquid product yield of 89.25% and the highest relative C 15 –C 18 hydrocarbon fraction of 95.51%. Furthermore, it exhibited a low relative cracking fraction of 2.74% and a low apparent DCOx/HDO ratio of 0.79. These findings demonstrate that the zeolite–alumina support composition can be tuned to modulate the liquid-product distribution and suppress undesirable cracking during PFAD deoxygenation.