Synthesis of NiMo catalysts supported on Mn-Al2O3 for obtaining green diesel from waste soybean oil
Résumé
The influence of adding manganese to an Al 2 O 3 support for preparing NiMo catalysts for the hydroconversion of soybean oil was herein evaluated. Two different Mn contents (1 and 5 mol % Mn) were used while Al 2 O 3-Mn x (x = 1 or 5 % mol Mn) were obtained by sol-gel method. The NiMo catalysts were obtained by wetness coimpregnation of nickel and molybdenum precursors onto the as-formed supports considering two different pH of impregnation (5 or 9). Solids were then characterized at the oxide state at different stages of preparation before being sulfided at 400°C for 4 h with 10 % H 2 S/H 2. Catalysts were then characterized at the sulfide state and evaluated for the hydroconversion of new and waste soybean oil at 380°C, P H2 = 40 bars. Results show clearly the superiority of NiMo catalysts supported on Al 2 O 3 with 1% mol Mn for the hydroconversion of new and waste soybean oil due to the stabilization of manganese oxide species on the alumina support helping to redisperse the Ni-promoted MoS 2 active phase. This study shows that through a precise control of the addition of manganese to Al 2 O 3 , it is possible to obtain very highly active NiMo catalysts for the hydroconversion of vegetable oils.