Hydroprocessing of jatropha oil and its mixtures with gas oil

Abstract

Hydroprocessing catalysts, sulfided Ni–W/SiO₂–Al₂O₃, Co–Mo/Al₂O₃ and Ni–Mo/Al₂O₃ have been developed, and their performances in hydroprocessing of jatropha oil and its mixtures with refinery gas oil compared in terms of, detailed product distribution in order to optimize the catalyst and conditions that can give maximum yield of desired transportation fuel such as diesel or kerosene (jet). C15–C18 hydrocarbon yield (diesel range) is highest (97.9%) over Ni–Mo catalyst, while it is 80.8% over Ni–W catalyst and surprisingly low (49.2%) over Co–Mo catalyst. Jatropha oil with high as well as low free fatty acid (FFA) contents could be hydroprocessed with little observable effect on reactor metallurgy. The isomers to n-paraffins (i/n) ratio is very low and different for the three types of catalysts- nearly 22–36 times higher for the hydrocracking (Ni–W) catalyst than that for the hydrotreating (Ni–Mo) catalyst. The hydrodeoxygenation pathway for oxygen removal from triglyceride is favored over the fresh Ni–Mo and Co–Mo catalysts, while decarboxylation/decarbonylation pathway is favored over the Ni–W catalyst. But, resulfidation of used Ni–Mo catalyst results in decarboxylation/decarbonylation route being slightly more favored. The yield of diesel range (250–380 °C) product during co-processing varied between 88–92% for the Ni–Mo catalyst. Hydrodesulfurization of gas oil is better during co-processing with jatropha oil. The activation energy for overall S-removal is much lower than that for overall O-removal. Densities of the products were also observed to meet the required specification.