Lubricant compositions comprising colloidal dispersions of rare earth compounds and catalytic combustion of engine exhaust soots therewith

Abstract

Engines equipped with an exhaust line fitted with a particulate filter, in which the particulates contained in the exhaust gas are trapped on such filter, and wherein the trapped particulates are periodically burned off, are operated by improvedly catalyzing the combustion of said particles utilizing a composition containing mixture of a lubricating oil and a colloidal dispersion as the engine-lubricating composition, which dispersion includes particles of at least one compound of at least one rare earth and an amphiphilic agent.

1 .- 12 . (canceled) 
   
   
       13 . A method for operating an engine producing exhaust gases that contain particulates and equipped with a muffler provided with a particulate filter, in which the particulates are trapped on said filter and the catalytic combustion of the trapped particulates is carried out periodically, wherein, to assist catalyzing the combustion of said particulates, a lubricant composition which comprises admixture of:
 a lubricating oil; and   a colloidal dispersion of particles of at least one compound of at least one rare earth and an amphiphilic agent which at least partially interacts therewith, is provided for said engine.   
   
   
       14 . The method as defined by  claim 13 , wherein said at least one rare earth is selected from the group consisting of cerium, lanthanum, yttrium, neodymium, gadolinium and praseodymium. 
   
   
       15 . The method as defined by  claim 13 , wherein the colloidal dispersion comprises particles of a compound of iron and of a rare earth. 
   
   
       16 . The method as defined by  claim 13 , said amphiphilic agent comprising an acid. 
   
   
       17 . The method as defined by  claim 16 , said acid comprising a carboxylic acid having from 10 to 60 carbon atoms. 
   
   
       18 . The method as defined by  claim 16 , said acid being selected from the group consisting of fatty acids of tall oil, of soybean oil, of tallow or of linseed oil, oleic acid, linoleic acid, stearic acid and isomers thereof, pelargonic acid, capric acid, lauric acid, myristic acid, dodecylbenzenesulfonic acid, 2-ethylhexanoic acid, naphthenic acid, hexoic acid, toluenesulfonic acid, toluenephosphonic acid, laurylsulfonic acid, laurylphosphonic acid, palmitylsulfonic acid and palmitylphosphonic acid. 
   
   
       19 . The method as defined by  claim 13 , wherein the colloidal dispersion comprises particles of at least one compound of at least one rare earth, at least 90% of such particles being single-crystal particles. 
   
   
       20 . The method as defined by  claim 19 , wherein the particles have a D 50  value ranging from 1 to 5 nm 
   
   
       21 . The method as defined by  claim 13 , wherein the content of rare earth, optionally of rare earth and of iron, expressed as metal element, comprising the colloidal dispersion in the lubricating composition, is at most 15% by weight of the total weight thereof. 
   
   
       22 . The method as defined by  claim 13 , utilizing a lubricant composition which comprises the lubricating oil and the colloidal dispersion prepared prior to providing same in the engine. 
   
   
       23 . The method as defined by  claim 13 , wherein the engine is a diesel engine or a petrol engine. 
   
   
       24 . The method as defined by  claim 13 , carried out employing an engine operating with a fuel which contains a catalyst for combustion of the particulates or with an engine equipped with a muffler which comprises a catalytic particulate filter. 
   
   
       25 . A lubricant composition which comprises admixture of:
 a lubricating oil; and   a colloidal dispersion of particles of at least one compound of at least one rare earth and an amphiphilic agent which at least partially interacts therewith.   
   
   
       26 . The lubricant composition as defined by  claim 25 , said amphiphilic agent comprising an acid. 
   
   
       27 . The lubricant composition as defined by  claim 25 , said colloidal dispersion comprising particles of at least one cerium compound. 
   
   
       28 . The lubricant composition as defined by  claim 27 , said colloidal dispersion optionally comprising particles of another rare earth and of iron. 
   
   
       29 . The lubricant composition as defined by  claim 28 , said colloidal dispersion comprising particles of a mixed oxide and/or a hydrated mixed oxide. 
   
   
       30 . The lubricant composition as defined by  claim 25 , said colloidal dispersion comprising particles of at least one compound of at least one rare earth elected from the group consisting of cerium, lanthanum, yttrium, neodymium, gadolinium and praseodymium. 
   
   
       31 . The lubricant composition as defined by  claim 25 , said colloidal particles comprising a complexing agent. 
   
   
       32 . The lubricant composition as defined by  claim 25 , said colloidal particles being suspended in an organic liquid phase. 
   
   
       33 . An internal combustion engine oil comprising the lubricant composition as defined by  claim 25 .