Solvent-free deoxygenation of low-cost fat to produce diesel-like hydrocarbons over Ni–MoS2/Al2O3–TiO2 heterogenized catalyst

This research presents the conceptual clarification for the waste chicken fat catalytic deoxygenation as a feedstock for high-quality green diesel hydrocarbon fuel production. For the first time, the deoxygenation catalytic runs were executed over Ni–MoS2/Al2O3–(15%) TiO2 catalytic system in a fixed bed down flow reactor at reaction temperatures of 400–450 °C, liquid hourly space velocity of 1.0–4.0 h−1, H2 pressure of 6.0 MPa and H2/Feedstock of 600 v/v. The principal characterization tools such as Fourier transform infrared spectroscopy, X-ray diffraction and surface area were employed for studying the physicochemical properties of the fresh NiO–MoO3/Al2O3–(15%) TiO2 and Ni–MoS2/Al2O3–(15%) TiO2 catalysts. Meanwhile, the mentioned tools were used for the characterization of spent and regenerated Ni–MoS2/Al2O3–(15%) TiO2 catalysts. The conversion, product yield and the impact of varying the processing conditions on the deoxygenation pathways, including decarbonylation/decarboxylation and hydrodeoxygenation, were investigated. The potential impacts of the catalytic system recovery and recycling were also considered. The results obtained demonstrate that increasing the reaction temperature increases the percent of conversion toward the light hydrocarbons (gasoline/kerosene range) production while reduces the required product yield (diesel range, C16–C18) with slight influence for increasing the liquid hourly space velocity from 1 to 4 h−1. In addition, the oxygen removal from waste chicken fat by hydrodeoxygenation mechanism was favored at a low reaction temperature of 400 oC, while its removal by decarboxylation and decarbonylation mechanisms was enhanced by increasing the reaction temperature above 400 oC. The reaction kinetics study reveals that the deoxygenation reaction follows the second-order mechanism.