Bifunctional MoS₂/Al₂O₃-Zeolite Catalysts in the Hydroprocessing of Methyl Palmitate

A series of bifunctional catalysts, MoS₂/Al₂O₃ (70 wt.%), zeolite (30 wt.%) (zeolite-ZSM-5, ZSM-12, and ZSM-22), and silica aluminophosphate SAPO-11, were synthesized for hydroconversion of methyl palmitate (10 wt.% in dodecane) in a trickle-bed reactor. Mo loading was about 7 wt.%. Catalysts and supports were characterized by different physical-chemical methods (HRTEM-EDX, SEM-EDX, XRD, N₂ physisorption, and FTIR spectroscopy). Hydroprocessing was performed at a temperature of 250-350 °C, hydrogen pressure of 3.0-5.0 MPa, liquid hourly space velocity (LHSV) of 36 h^-1, and an H₂/feed ratio of 600 Nm³/m³. Complete conversion of oxygen-containing compounds was achieved at 310 °C in the presence of MoS₂/Al₂O₃-zeolite catalysts; the selectivity for the conversion of methyl palmitate via the 'direct' hydrodeoxygenation (HDO) route was over 85%. The yield of iso-alkanes gradually increases in order: MoS₂/Al₂O₃ < MoS₂/Al₂O₃-ZSM-12 < MoS₂/Al₂O₃-ZSM-5 < MoS₂/Al₂O₃-SAPO-11 < MoS₂/Al₂O₃-ZSM-22. The sample MoS₂/Al₂O₃-ZSM-22 demonstrated the highest yield of iso-alkanes (40%). The hydroisomerization activity of the catalysts was in good correlation with the concentration of Brønsted acid sites in the synthesized supports.