Process for the Purification of Spent Process Oil

Abstract

A process for the purification of spent process oil, which process comprises, mixing the process oil with an additive comprising a liquid mixture of a) at least one alkanolamine, and b) at least one member selected from the group consisting of alkanoic acids, and alkenoic acids having from 6 to 18 carbon atoms and the melting point/points such that the mixture of a) and b) is liquid at the temperature at which the process is carried out, with a pH-value of said mixture of a) and b) in the range of 5 to 8, preferably 6 to 7, and most preferably 6.3, and said mixture being substantially insoluble in the process oil, forming a two phase mixture upon mixing, and subsequent separation of the phase with process oil from the phase with said mixture of a) and b) with absorbed contaminants. The invention further provides use of alkanoic acids and alkenoic acids having from 6 to 18 carbon atoms in the preparation of a mixture for the purification of spent process oil as well as the use of alkanolamines.

1 . A process for the purification of spent process oil, comprising: 
 mixing spent process oil with an additive comprising a liquid mixture of: 
 a) at least one alkanolamine, and  
 b) at least one member selected from the group consisting of an alkanoic acid, and an alkenoic acid having from 6 to 18 carbon atoms, wherein the melting point of the alkanoic acid and the alkenoic acid is such that the mixture of a) and b) is liquid at a temperature at which the process is carried out, wherein a pH-value of said mixture of a) and b) is in the range of 5 to 8, and said mixture is substantially insoluble in process oil,  
   forming a two phase mixture upon mixing; and    separating a phase with process oil from a phase with said mixture of a) and b) wherein the mixture of a) and b) absorbed contaminants.    
   
   
       2 . A process according to  claim 1 , wherein a) is selected from the group consisting of monoethanolamine, diethanolamine and triethanolamine.  
   
   
       3 . A process according to  claim 1 , wherein a) is triethanolamine.  
   
   
       4 . A process according to  claim 1 , wherein b) is selected from the group consisting of lauric acid, oleic acid, pentadecanoic acid, decenoic acid, 2- ethylhexanoic acid, and caprylic acid.  
   
   
       5 . A process according to  claim 1 , wherein b) is selected from the group consisting of 2-ethylhexanoic acid and caprylic acid.  
   
   
       6 . A process according to  claim 1 , wherein said separating of the two phase mixture is carried out by one method or a combination of methods selected from the group consisting of static settling, centrifugal separation, vacuum filtration, press filtration, pre-coat filtration and centrifugal filtration.  
   
   
       7 . A process according to  claim 1 , wherein the mixture of a) and b) is added in an amount of 0.0001 to 10% by weight, calculated on the weight of the spent process oil.  
   
   
       8 . A process according to  claim 1 , wherein said additive further comprises at least one agent selected from the group consisting of monoethylene glycol, dipropylene monoethylether, glycerol, and propylene glycol.  
   
   
       9 . A process according to  claim 1 , which is carried out at a temperature above 10° C.  
   
   
       10 . Use of at least one member selected from the group consisting of alkanoic acid, and alkenoic acid having from 6 to 18 carbon atoms in the preparation of a mixture for purification of spent process oil.  
   
   
       11 . Use of at least one alkanolamine in the preparation of a mixture for purification of spent process oil.  
   
   
       12 . Use of a liquid mixture for purification of spent process oil, said liquid mixture comprising: 
 a) at least one alkanolamine, and    b) at least one member selected from the group consisting of alkanoic acid, and alkenoic acid having from 6 to 18 carbon atoms, wherein the melting point of the alkanoic acid and the alkenoic acid is such that the mixture of a) and b) is liquid at a temperature at which the process is carried out.    
   
   
       13 . Use according to  claim 10  wherein the spent process oil is selected from the group consisting of mineral oil, rolling oil, honing oil, drawing oil and engine lubricating oil.  
   
   
       14 . Use according to  claim 10  wherein the temperature is above 10° C.