Production of Synthetic Diesel by Hydrotreatment of Jatropha Oils Using Pt-Re/H-ZSM-5 Catalyst

Renewable green diesel-type alkanes can be produced by hydrotreating jatropha oil and vegetable oils at standard hydrotreating conditions (i.e., 543-573 K) with Pt/H-ZSM-5 catalysts, which are active under the weight ratio of jatropha or vegetable oil/catalyst of 1. The carbon molar yield of straight chain C-15-C-18 alkanes was similar to 80% for hydrotreating pure jatropha oil. However, under the jatropha oil/catalyst weight ratio of 10, being important from a practical point of view, the alkanes yield falls to only 2.3%. Under a high jatropha oil/catalyst ratio of 10, rhenium-modified Pt/H-ZSM-5 catalyst is found to be effective for raising the C-15-C-18 alkanes yield. The yield of C-15-C-18 alkanes is 67% at an optimun Re/Almolar ratio of 0.8. Investigation of catalyst natures indicates that metallic Pt and Re are independently present on the surface, but synergism of these two metals could play an important role in the hydrotreating reaction, even at a high ratio of jatropha oil/catalyst of 10. The reaction pathway involves hydrogenation of the C=C bonds of the jatropha oils followed by mainly hydrodeoxygenation with decarbonylation and decarboxylation to form C-15-C-18 straight chain alkane mixtures.