2008 Volume 51 Issue 3 Pages 165-173
Synthetic crude oils (SCOs) derived from oil shale, coal, and oil sands contain relatively large amounts of heteroatoms such as nitrogen and sulfur, and severe hydrorefining conditions are necessary to convert SCOs into substitute transport fuels. In this study, extraction of nitrogen compounds from SCOs by complex formation with CuCl2.2H2O was carried out and the denitrogenated oils were hydrotreated to explore the effect of nitrogen pre-removal on hydrodenitrogenation (HDN) and hydrodesulfurization (HDS). Light gas oil fractions derived from shale oil, coal-derived liquid, and pyrolysis product of Athabasca bitumen were used as feedstocks. Hydrotreatment tests were carried out using a batch-type autoclave and commercial NiMo/Al2O3 catalyst at 350°C for 2-4 h under H2 initial pressure of 5 MPa. The results showed that basic and heterocyclic nitrogen compounds could be separated efficiently from SCO by complex formation. The pre-removal of nitrogen compounds greatly enhanced the HDN reaction rates and greatly reduced the residual nitrogen content. The recovery of CuCl2.2H2O was also possible by simply washing CH2Cl2 solution containing the complex with water. The proposed method is another option for the conversion of SCO to a high quality feedstock suitable for production of clean diesel fuels.