Lube-Tech
hydrolysis depends upon the type/quantity of catalyst, temperature, type of VO, and other such factors. These FFAs then can be esterified with alcohols of different chain lengths to produce biolubricants. This method can be used to produce biodiesel/biolubricant from low-quality VO (waste cooking oils, animal fats, etc.) as an alternative to the transesterification process and provides the possibility of overcoming many problems associated with the recovery of the by-product glycerol. The FFAs obtained from hydrolysis are easily converted into fatty amides, amines, alcohols, or ionic liquids that are used as multifunctional additives for lubricants. Gusain et al. prepared tetrabutylammonium ionic liquids having fatty acid anions of variable chain length and unsaturation (caprate, laurate, myristate, palmitate, and oleate) which improved the tribological properties of mineral base stock significantly2
. It is also reported
that the tetrabutylammonium ionic liquids having various anions, viz., stearate, oleate, and linoleate improved the friction and antiwear properties when added to polyol ester lube base oil, for the steel surfaces.
Preparation of fatty amides and amines Amines and amide derivatives of oils have versatile applications in different industries including friction modifiers or antiwear additives in engine oils. The amides are prepared by catalytic aminolysis of fatty acids/esters with ammonia or primary/secondary amines. For the preparation of amines, the fatty esters/ acids are aminolysed with ammonia followed by dehydration and hydrogenation with suitable catalysts. These additives have better environmental footprint than the commercial ZDDP-type antiwear additives.
Partially neutralised fatty amine salts were used as friction modifier for lubricants especially for internal combustion engines. Soybean oil-based fatty amide was used as a rheology modifier additive in coatings. The chemistry of tribology of fatty amines on steel surfaces was mentioned by Nalam et al.3
. 28 LUBE MAGAZINE NO.172 DECEMBER 2022
PUBLISHED BY LUBE: THE EUROPEAN LUBRICANTS INDUSTRY MAGAZINE
No.143 page 4
Amide derivatives of non-edible high free fatty acids containing triglycerides of waste cooking oil, karanja
oil, and jatropha oil using Li doped CaO-Ca(OH)2 heterogeneous nano-catalyst are used as diesel fuel additives and have been found to improve the cetane number from 52.6 to 56.1 and lubricity from 460 to 247 μm of diesel fuel.
Epoxidation and carbonation of fatty acids/ esters
Epoxidation, an important pathway towards improving the oxidation stability, is generally carried out by reaction of the fatty esters/acids with a peroxy acid (peracetic, performic, m-chloroperbenzoic acid) in presence of a catalyst. The extent of reaction depends on several experimental conditions like temperature, type of peracid, catalyst, solvent, stoichiometry, time, contacting patterns (batch/ semi-batch mode/ azeotropic distillation) etc. These epoxidised derivatives are used to prepare base stock and antiwear/antifriction additives having considerably better performance than conventional petroleum- based lubricants. The opening of oxirane rings of the epoxy fatty esters/acids with different nucleophiles (alcohols, thiols, amines, acids) in presence of catalysts also produce versatile products that are used as biolubricant base stocks/additives, bio-plasticisers, and other industrially useful chemicals. Epoxy derivatives of oils may be converted into cyclic carbonate derivatives by reacting with CO2
in presence of catalysts. These
carbonate derivatives are also used to prepare lubricant additives and other essential value-added materials. These have the added advantage of consuming and utilising atmospheric CO2
. The
synthesised compounds showed potential application as industrial lubricants or fuel additives. Fig. 1 shows epoxidation and carbonation reactions of VO.
Polymerisation
Polymerisation is a potential way to improve oxidation stability of VO. Polymerised plant oils have extensive application as additives/base stocks in the
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