Diesel Fuel Production by Catalytic Hydrogenation of Light Cycle Oil and Waste Cooking Oil Containing Gas Oil

Abstract

Heterogeneous catalytic hydrogenation of mixtures containing straight run gas oil (70–85 %), light cycle oil (LCO) (15 %) and waste cooking oil (WCO) (0–15 %) was investigated on commercial CoMo/Al2O3 catalyst. We determined that with the application of LCO in the feedstocks the density of the products can be increased. With the formed n- and isoparaffins (from the WCO content of the feedstocks) the higher aromatic content (lower cetane index) of the products—caused by the unconverted LCO components—could be partly compensated and the second generation biocomponent content can be assured. On the pre-sulphided catalyst the best products could be produced in case of T = 360 °C, P = 30 bar, LHSV = 1.0 h−1, H2/feedstock ratio = 420 Nm3/m3 process parameters and 10–15 % WCO content of feedstocks. The polyaromatic content of the main products was under 8 w/w% applying the advantageous process parameters, even though the LCO content of the feedstocks. The cetane indexes of the main products changed between 48 and 50, their sulphur content was under 10 mg/kg until blending 10 % of WCO, in case of 15 % WCO content was still just 13 mg/kg. We concluded, that increasing the triglyceride content of feedstocks above 15 % is not recommended, because of the increased oxygen content the sulphur removal reactions are forced back. The cause of this is that the sulphur- and oxygen removal reactions are occuring on the same active sites of the catalyst, as well as the aromatic hydrogenation reactions, which are contributing to achieve the high degree of desulphurization.