THE HYDROTREATMENT OF AN UNSATURATED FATTY ACID VEGETABLE OIL TO HYDROCARBONS OVER NI/SIO_2 – AL_2O_3

摘要

In this study, sunflower oil was hydrotreated in the presence of a nickel catalyst with the objective tornevaluate the effect of reaction parameters on the characteristics of the reaction product. The effect of reactionrntemperature, reaction time and initial hydrogen pressure on the conversion of the triglyceride feedstock, the naphtha,rnkerosene and diesel yield and the liquid product yield was investigated. The reaction product during hydroprocessingrnis influenced by the type of catalyst used, the reaction conditions as well as the nature of the feedstock. Experimentsrnwere conducted using a cylindrical bench scale batch reactor with an inside volume of 350 cm~3. Reactions wererncarried out at temperatures of 390℃ to 420℃ and initial hydrogen pressures of 5 MPa – 11MPa. The effect of usingrna catalyst versus no catalyst during hydroprocessing was also compared. The gas product was analysed using gasrnchromatography with FID and TCD detectors while the liquid product was analysed using GC-MS. It was found thatrntemperature and reaction time has a significant effect on the composition of the liquid product. At a temperature ofrn390℃ with a reaction time of 30 minutes, the diesel yield was found to be 68% to be reduced to 29.6% at a reactionrntemperature of 420℃ with a reaction time of 60 minutes. At more harsh conditions the concentration of lower boilingrncompounds were found to increase due to the effect of side reactions such as cracking, aromatization and cyclization.rnIt was also found that liquid yield decreased with an increase in reaction temperature due to gas formation. Ni/SiO_2-rnAl_2O_3 was found to be a promising catalyst for the hydrotreatment of triglyceride-based feedstock due to its relativelyrnlow cost and no need for sulfidation. A disadvantage of this catalyst is the formation of methane during the reactionrnwhich could have a negative effect on optimal hydrogen consumption.