EVALUATION OF COTTONSEED OIL AS CO-FEEDSTOCK FOR THE HYDROPROCESSING OF PETROLEUM MIDDLE DISTILLATES FOR DIESEL FUEL PRODUCTION

摘要

Mandatory blending of biodiesel into petroleum diesel came to effect in 2015 in South Africa. Thernavailability of biodiesel to implement this mandate however poses a challenge for local biodiesel producers andrnpetroleum refineries. One alternative that could contribute to the solution of this problem is upstream blending ofrntriglyceride oil into the hydrotreater feed of existing refining facilities. Cottonseed oil, a by-product from the cottonrnwool industry could be considered a co-feed candidate for diesel fuel production. In this study, the effect of catalystsrnand reaction conditions on the composition and yield of renewable bio-hydrocarbon fuels from cottonseed oil andrnhybrid diesel fuel from atmospheric gas oil/ cottonseed oil blends were evaluated .Experiments were conducted usingrna cylindrical bench-scale batch reactor with a volume of 350 cm~3 and a maximum pressure rating of 20 MPa. Forrncottonseed oil the conversion performance order was found to be NiMo-Al_2O_3 (99.86%)> sulphided CoMo-Al_2O_3rn(98.9%)> reduced Ni/SiO_2-Al_2O_3 (96.8%). The highest diesel yield obtained at 390℃ reaction temperature and initialrnhydrogen pressure of 9 Mpa were 493g.kg-1 for the CoMo-Al_2O_3 catalyst, 492g.kg-1 for the NiMo-Al_2O_3 catalyst andrn444g.kg-1for the NiSiO_2-Al_2O_3 catalyst. For cottonseed oil/gas oil blends up to 20% cottonseed oil, no negative effectrnwas observed on the hydrodesulphurisation of gas oil. Simulated distillation data showed that cracking is promotedrnwith the addition of cottonseed oil and the diesel yield increases with an increase in cottonseed oil concentration.