Co-processing of straight run gas oil with used cooking oil and animal fats

Abstract

Co-processing experiments of straight run gas oil (SRGO) with used cooking oil (UCO), and category three animal fat were performed in a hydrotreatment pilot plant. Liquids and gaseous products obtained were analysed and quantified. The aim of the work was the study of the effect of the triglycerides feedstocks co-processing with the diesel fuel on the desulphurized gasoil properties, as well as their impact on the hydrodesulfurization (HDS) and hydrodenitrogenation (HDN) catalyst activities. These results were compared with the co-processing test of refined palm oil. Experiments were performed in a pilot plant that reproduced the hydrotreatment of diesel oil with a conventional NiMo/Al2O3 catalyst, under the following conditions: 350 °C 5.5 MPa, LHSV 2 h−1 and a H2 to feed oil ratio of 340 NL/L. The ratio SRGO/triglycerides feedstock was always 80/20 wt.%. At these operating conditions, linear paraffins (nC15–nC18) were the main reaction product (79–85 wt.%), followed by light gases (CO, CO2 and C3H8) and water as by-products. The increment in paraffin content of the liquid product produced a significant variation of some of gasoil properties (density at 15 °C and cetane index). A decrease in the catalytic activity (HDS/HDN) was also observed in the co-processing stages, particularly when animal fat was co-processed.