Study On Desulfurization Of Vacuum Residue By Molecular Oxygen Oxidation-Pyrolysis Process

Traditional residue hydrodesulfurization process needs to operate under high temperature and pressure and consumes a lot of hydrogen.Oxygen desulfurization process is a very promising desulfurization process operating under mild environment.Molecular oxygen（air,oxygen,ozone）is used as oxidant,which has the advantages of convenient source and friendly environment.However,oxidative desulfurization technology has been widely used in the deep desulfurization of diesel oil.So far,there are few reports on the application of oxidative desulfurization technology to residue desulfurization.The thermal conversion of vacuum residue is an important processing method of the residue.The S=O=S bond in the sulfone can be removed from the hydrocarbon at high temperature and removed as SO₂ gas.First,the sulfur-containing compound in the vacuum residue is oxidized to a sulfone-based substance,and then the oxidized residue is poured into a thermal conversion device,and the heat of the thermal conversion device is used to remove sulfur at the same time as the thermal conversion of the residue.First,sulfur compounds in vacuum residue are oxidized to sulfones,and then the oxidized residue is poured into the thermal conversion unit.The heat of the thermal conversion unit is used to remove sulfur at the same time of the thermal conversion of residue.Therefore,using molecular oxygen as oxidant,the oxidative desulfurization effect of vacuum residue in different systems was discussed,and a combined process of molecular oxygen oxidation and pyrolysis was proposed.In this paper,CNOOC Huizhou Refining and Chemical Vacuum Residue is used as raw material,its total sulfur content is 4.5%.With air as oxidant,vacuum residue and diluent were mixed evenly in a certain mass ratio and reacted in autoclave.The oxidized sample is connected with the distillation unit to remove the diluent and get the oxidized oil,which is then pyrolyzed in a high-pressure autoclave at 380℃.The experimental results show that the desulfurization rate of air oxidation is 13.4%under vacuum residue:diluent=1:1（mass ratio）,air pressure of 3 MPa,autoclave rotor speed of 450 r/min,reaction temperature of 145℃and reaction time of 8 h.In this paper,the desulfurization efficiency of vacuum residue from CNOOC Huizhou Refinery and Chemical Company was investigated by using oxygen as oxidant.The results show that the desulfurization rate after18 hours is 18.3%under the conditions of residual oil:water=1:1（mass ratio）,oxygen pressure 1.5 MPa,reaction temperature 145℃,oxidation oil pyrolysis temperature 380℃,autoclave rotor speed 450 r/min,and residue:diluent:oxidizer=1:1（mass ratio）,oxygen pressure 3 MPa and reverse reaction.The desulfurization rate of vacuum residue is 30.4%after 8 hours reaction at 145℃,380℃and 450 r/min rotational speed of autoclave rotor.In vacuum residue,diluent:oxidizer=1:1:1（mass ratio）,30%peracetic acid with 10%residual oil mass is added,oxygen pressure is 3 MPa,reaction temperature is 145℃and oxidation oil pyrolysis temperature is 380℃with450 r rotational speed of autoclave rotor.Under min,the desulfurization rate was 35.7%after 6 h of reaction.In this paper,the ozonation of residue-diluent-glacial acetic acid system was discussed with the vacuum residue from Huizhou Refinery and Chemical Company of CNOOC as raw material and ozone as oxidant.The results show that at room temperature,when the flow rate of oxygen is 1 L/min,the concentration of ozone is 80 mg/L,residue:diluent:glacial acetic acid=1:1:1（mass ratio）,the pyrolysis temperature of oxidized oil is 380℃,and the desulfurization rate is 43.3%after 10 hours of reaction.On this basis,the amount of solvent was increased,residue:diluent:glacial acetic acid=1:2:1.5（mass ratio）,desulfurization rate was 43.7%after 8 hours of reaction.In this paper,ozonation of vacuum residue from Huizhou Refinery and Chemical Company of CNOOC was studied by using ozone as oxidant.The results show that at room temperature,when the flow rate of oxygen is 1L/min,the concentration of ozone is 80 mg/L,the residue oil:diluent:oxidizing assistant=1:1:1（mass ratio）,the pyrolysis temperature of oxidized oil is 380℃,the desulfurization rate after 10 hours is 40.4%,which exceeds the desulfurization rate of residue-diluent-glacial acetic acid system at the same reaction time.The desulfurization rate was 45.7%after 8 hours of oxidation when the amount of solvent was increased as residue:diluent:oxidizing assistant=1:2:1.5（mass ratio）.