Catalytic Hydrotreating of Crude Pongamia pinnata Oil to Bio-Hydrogenated Diesel over Sulfided NiMo Catalyst

Abstract

This work studied the catalytic activity and stability of Ni-MoS2 supported on γ-Al2O3, SiO2, and TiO2 toward deoxygenation of different feedstocks, i.e., crude Pongamia pinnata oil (PPO) and refined palm olein (RPO). PPO was used as a renewable feedstock for bio-hydrogenated diesel production via catalytic hydrotreating under a temperature of 330 °C, H2 pressure of 50 bar, WHSV of 1.5 h−1, and H2/oil (v/v) of 1000 cm3/cm3 under continuous operation. The oil yield from a Soxhlet extraction of PPO was up to 26 wt.% on a dry basis, mainly consisting of C18 fatty acids. The catalytic activity in terms of conversion and diesel yield was in the same trend as increasing in the order of NiMo/γ-Al2O3 > NiMo/TiO2 > NiMo/SiO2. The hydrodeoxygenation (HDO) activity was more favorable over the sulfided NiMo supported on γ-Al2O3 and TiO2, while a high DCO was observed over the sulfided NiMo/SiO2 catalyst, which related to the properties of the support material and the intensity of metal–support interaction. The deactivation of NiMo/SiO2 and NiMo/TiO2 occurred in a short period, due to the phosphorus and alkali impurities in PPO which were not found in the case of RPO. NiMo/γ-Al2O3 exhibited the high resistance of impure feedstock with excellent stabil-ity. This indicates that the catalytic performance is influenced by the purity of the feedstock as well as the characteristics of the catalysts.