Research On Hydrogenation Of Coal Oil Co-Refining Products To Produce Clean Fuel

In this dissertation,a washing oil（WO）produced by The Coal Coking Company of Masteel and a coal oil co-refining light oil（COLO）from Shaanxi Yanchang Petroleum（Group）Co.Ltd.,were used as raw materials.The hydrogenation and co-hydrodesulfurization in fixed bed and batch reactor with NiMoS/γAl₂O₃,CoMoS/ZrO₂,10%wt Ni/γAl₂O₃-Si and nanosheets of Ni as catalysts were carried out.The effects of solvent,temperature,catalyst and reaction time on the sulfur content and composition of hydrogenated oil,especially naphthenic hydrocarbon content,were investigated,and the catalysts were also characterized by the different methods.The results show that the sulfur content of COLO is high as 2282 mg/l.After fraction cutting,it is found that the sulfur content of the lighter 180℃fraction is the lowest as 280-500mg/l.The sulfur content of 180℃fraction can be reduced from283.6 mg/l to 56.4 mg/l with the desulfurization rate of 80.1%by the hydrodesulfurization in batch reactor,suggesting that the sulfur in light fraction is easier to be removed by hydrogenation.Therefore,in order to obtain fuel oil with extremely low sulfur content,light fraction should be used as raw material for hydrorefining desulfurization.The highest hydrodesulfurization rate of 180℃fraction was 59.8%obtained at 300℃.With rising temperature to 380℃,the hydrodesulfurization rate is greatly reduced to 21.7%.With the increasing of reaction time from 40 min to 1 h,and the desulfurization rate increases from 37.0%to 54.2%,and further extending reaction time to 1.5 h,the desulfurization rate decreases to28.6%.The activity of the three catalysts for hydrodesulfurization of 180℃distillate is in order of NiMoS/γAl₂O₃>CoMoS/ZrO₂>10%wt Ni/γAl₂O₃-Si.The modified 10%wt Ni/γAl₂O₃-Si by silicon has a larger specific surface area of 199.7 m²/g,but it’s activity is still slightly lower than that of CoMoS/ZrO₂due to it’s single metal loading,and the desulfurization rates of the two catalysts are 14.1%and 19.5%,respectively.NiMoS/γAl₂O₃has a large specific surface area of 147.4 m²/g,average pore size is5.78 nm,and good dispersion of active components,showing the highest hydrodesulfurization activity with a desulfurization rate of 41.9%.After hydrodesulfurization of 180℃fraction with tetralin as hydrogenation solvent by NiMoS/γAl₂O₃catalyst for 10 hours,the sulfur content of hydrodesulfurized oil is 9.7mg/l with the highest sulfur removal rate of 85.9%.The saturated naphthenic content of the oil is 29.92%detected by GCMS,which was able to meet the basic requirements of jet fuel.When COLO and WO at a mixing ratio of 1:1 are co-hydrogenated with NiMoS and Ni nanosheet catalysts,the hydrogenated oils obtained have the highest content of naphthenic hydrocarbons with 21.99%and 23.21%respectively.Further increasing the ratio of WO to 7:3,the content of naphthenic hydrocarbons by NiMoS catalyst is slightly reduced to 15.98%,while the Ni nanosheet catalyst quickly decreases to2.77%.The content of N and S-containing compounds reaches the minimum value of0.15%at a mixing ratio of 3:7 after co-hydrogenation of COLO and WO by NiMoS catalyst.Further increasing the WO ratio,the content of N and S-containing compounds in the hydrogenated oil continues to increase.Because the sulfur compounds in the WO,such as benzothiophene and oxygen-containing sulfides,are difficult to remove during the hydroprocessing.