Method for producing recycled lubricating base oil from waste lubricating oil and recycled lubricating base oil produced thereby

Abstract

According to an embodiment, a method for producing a recycled lubricating base oil from waste lubricating oil is proposed, the method including a) first pretreating the waste lubricating oil, b) performing distillation to recover a fraction having a specific boiling point from the first pretreated waste lubricating oil, c) second pretreating the fraction recovered in the distillation operation, and d) hydroprocessing the second pretreated fraction in the presence of a catalyst. The recycled lubricating base oil produced by the above method has a viscosity index (VI) equal to or greater than 130. The proposed method makes it possible to produce a high-grade lubricating base oil using only waste lubricating oil as a feed, thereby reducing the cost of raw materials for production of lubricating base oil, and having the advantage of being environmentally friendly.

What is claimed is: 
     
         1 . A method for producing a recycled lubricating base oil from waste lubricating oil, the method comprising:
 a first pretreating operation performed on the waste lubricating oil to form a first pretreated waste lubricating oil;   subjecting the first pretreated waste lubricating oil to a distillation operation to recover a fraction of the first pretreated waste lubricating oil having a specific boiling point;   a second pretreating operation performed on the recovered fraction of the first pretreated waste lubricating oil recovered in the distillation operation to form a second pretreated fraction of the waste lubricating oil; and   a hydroprocessing operation performed on the second pretreated fraction of the waste lubricating oil in the presence of a catalyst to produce a recycled lubricating base oil having a viscosity index (VI) equal to or greater than 130.   
     
     
         2 . The method of  claim 1 , wherein the waste lubricating oil prior to the first pretreating operation has a viscosity index of equal to or less than 120, a sulfur content of equal to or greater than 10,000 ppm, and a nitrogen content equal to or greater than 300 ppm. 
     
     
         3 . The method of  claim 1 , wherein the first pretreating operation comprises a coagulant addition process, a centrifugal separation process, or a combination thereof. 
     
     
         4 . The method of  claim 1 , wherein the distillation operation comprises an atmospheric distillation, a vacuum distillation, or a combination thereof. 
     
     
         5 . The method of  claim 1 , wherein the second pretreating operation comprises solvent extraction. 
     
     
         6 . The method of  claim 1 , wherein in the hydroprocessing operation, a proportion of an unsupported catalyst in the catalyst is 20% to 70% by volume based on the total volume of the catalyst. 
     
     
         7 . The method of  claim 1 , wherein the catalyst comprises a metal including Ni, W, Mo, Co, or a combination thereof. 
     
     
         8 . A recycled lubricating base oil having a sulfur content equal to or less than 5 ppm, a saturation equal to or greater than 90%, and a viscosity index (VI) equal to or greater than 130. 
     
     
         9 . The recycled lubricating base oil of  claim 8 , wherein the recycled lubricating base oil has a kinematic viscosity of 4 to 5 cSt at 100° C. and a pour point equal to or less than −15° C. 
     
     
         10 . A recycled lubricating base oil obtained by the method of  claim 1 , wherein the recycled lubricating oil has a sulfur content equal to or less than 5 ppm, and a saturation equal to or greater than 90%. 
     
     
         11 . The recycled lubricating base oil of  claim 10  further having a viscosity index (VI) equal to or greater than 130.