Development of Nickel Catalysts Supported on Titania for the Production of Green Diesel from Natural Triglycerides
The development of effective Ni/TiO2 catalysts for the transformation of sunflower oil to green diesel was studied in this work. The catalysts were prepared using four different techniques, namely Successive Dry Impregnation (SDI), Wet Impregnation (WI), Deposition Precipitation (DP) at room temperature using NH3 as precipitating agent and Deposition Precipitation (DP) at high temperature using urea as precipitating agent. The techniques were combined with the use of the following Ni precursor complexes: [Ni(H2O)6]2+ and [Ni(en)3]2+ (en: ethylenediamine). The catalysts were characterized and evaluated in a high pressure semi batch reactor. It was found that the yield of sunflower conversion to hydrocarbons in the diesel range (C15-C18) increases with nickel loading over the Ni/TiO2 catalysts up to 50% wt. Ni, which proved to be the optimum loading. The most suitable synthesis technique is the deposition - precipitation at high temperature using urea, which leads to a catalyst with a high porosity, a high specific surface area and a very good dispersion of the active phase (Ni0 crystallizer size).
Keywords - Biomass, Green (renewable) Diesel, Natural Triglycerides, Selective Deoxygenation, Ni Catalysts Supported on Titania.