Sulfonation of petroleum base oils
Sulfonation Of Petroleum Base Oils With Development Of The Emulsifiers
Sulfonation of Aromatic hydrocarbons , petroleum oil and vegetable oil has great importance in industry , in which useful surfactants material could be produced . Such surfactants could be used as detergent , emulsifying agent , softening agents , de emulsifying agents etc . The sulfonation of aromatic hydrocarbons is used to induce the sulfonyl group ( SO­3H ) while the sulfation of aliphatic organic molecules such as alcohols and olefins produce sulfuric acid esters . This work concerns mainly with sulfonation of petroleum base oil by converting its aromatic hydrocarbons into petroleum sulfonate and then study of the extraction process of these sulfonates , its development and uses . The sodium sulfonate of the average molecular weight ( 450- 500 glmol ) are widely used in composition of coolant fluids to function as a mulsifier in metal working applications.1,2,13-20 The sulfonates are synthesized specifically as additives for metal working fluids by sulfonating and neutralizing the sulfonic acid intermediates and finally the extraction of produced sulfonate from the oil sulfonates .
The formation of sulfonic acid intermediates can be carried out by the sulfonation of petroleum base oil by using gaseous sulfur trioxide ( SO3 ) diluted in air or Nitrogen3, 6 or by using sulfur dioxide which is dissolve in dichloroethane7 or by using the Oleum.8
Results And Discussion
Extraction of sodium sulfonate and its application in coolant fluid
Extraction of sodium sulfonate from oil solutions
The preliminary experiments of extraction of petroleum sulfonate from oil solutions by aqueous solution of isopropyl alcohol showed clearly the benefit of using the hexane a solvent in the extraction . However , the extraction process was more reliable and efficient when hexane acidic oil percentage was [ 1 : 1 ] and three layers were observed during 10 – 15 minutes whereas , in the absence of hexane as so wert it takes about 60 minutes or more .
The relation between the depth sulfonation ( amount of SO3 ) and the products of extraction process is given in the table ( 1 ) .
The results in table ( 1 ) show that the increase of the amount of sulfur trioxide ( more than 8 % w ) don’t lead to increase in yield of sulfonic acids , and the excess amount of sulfur trioxide may lead to formation of bisulfonate .
The average molecular weight of the aromatic hydrocarbons of this type of base oil was calculated to be 497 g / mal .
The value of weight was calculated as following .
Molecular weight of sulfonic acid =
The average molecular weight of aromatic hydrocarbons = 577 – 80 = 497g/mol ( whereas : 80 is the Mwt of SO3 ) and the yield of SO3 ( % )
= = 0.062
Where ( 31 ) is percentage of the aromatic hydrocarbons in oil ( % w ) that is the theoretical amount ( weight ) of sulfur trioxide required to transfer the whole amount of aromatic hydrocarbons to mono sulfonic acid become
= 0.062 x 80 = 4.96 . Therefore , the depth of sulfonation towards the enhancement of sulfur trioxide obove the theoretical amount ( 5 % ) will lead excess formation of bisulfonic acids . this observation is compatible to our results and conclusions .
The study results of the isopropyl alcohol effect of the emulsifier on the product of the oil after extraction , the product of the concentrated sulfonate and the content of the concentrated sulfonate ( % w ) are given in table ( 3 ).
The values given in table (2) are those obtained from the use of the sulfonate oil ( % of SO3 = 4% ) which is less the theoretical value required for the sulfonation of aromatic hydrocarbons in oil . However , these values indicate that the content of sulfonate in concentration is compatible with required usage of these sulfonates in coolant fluids2, and in the absence of a hydrocarbon solvent in the extraction process.1 However another extraction study of sodium sulfonate from sulfonated base oil ( SO3 = 8 % w ) which is greater than the theoretical value of the sulfonated aromatic hydrocarbon in oil and the results are given in table ( 3 ) .
From the results in the table (3) , the yield factor of sulfonate was calculated by -this method .
The content of sulfonate % w =
When , X = the content of the aromatic hydrocarbon of base oil ( = 31 % w )
M2 = the molecular weight of sodium sulfonate =
497 + 80 + 23 = 5509 g / mol
M1 = The molecular weight of aromatic hydrocarbon ( = 497 g /mol )
The yield of pure sulfonate ( 100 % sulfonate )
(% w ) = yield of sulfonate concentration x content of sulfonate in concentration.
Yield Factor % = yield of pure ssulfonate
The Content Of Sulfonate
The values of yield factor according to isopropyl alcohol concentration in extraction factor is given in table ( 4 ) .
All results of extraction process given in tables ( 3 ) and ( 4 ) are shown in figures 1 , 2 and 3 .
The decline in the yield of sulfonate and the increase of the oil yield after the extraction ( figure 1 ) is compatible with literature1 after enhancing the concentration of isopropyl alcohol in extraction factor . However , the highest value of the yield factor reached ( 90.3 % ) .When the concentration of isopropyl alcohol was 65 % which is twice the sulfonated oil . On the other hand , it was found that the more increase in the concentration of isopropyl alcohol , the more yield factor was obtained ( figure 3 ) .This conclusion was in contrary direction with the previously found relation.1 This is may be due to the change in chemical structure of formed sulfonic acids , that is during increase in the depth of sulfonation some mono sulfonic acids transfer to bisulfonic acid which causes in an enhancement in the yield factor for the sulfonic acids .
The standard concentration of isopropyl alcohol required to obtain the sulfonate not less than 50 % for the purpose of coolant fluids formation .
Experimentally , two cases were recognized . firstly , during the partial sulfonation of aromatic hydrocarbon ( table 2 ) , the concentration of isopropyl alcohol 30 % was used in the extraction process , whereas in the case of the depth sulfonation , the concentration of isopropyl alcohol should not be less than 45 % to ensure obtaining the required sulfonate concentration according to table ( 3 ) . However , the concentration of isopropyl alcohol was 55 % .
The application of petroleum sodium sulfonate in fabrication of coolant fluids .
The evaluation results of the stability of coolant fluids – lubrication of the emulsifier type which introduced in its composition petroleum sodium sulfonate ( table 5 ) .
The results given in table ( 5 ) are receiving considerable worldwide scientific and applied importance .
As shown in table ( 5 ) .
The content of sulfonate in sodium concentrated sulfonate which was extracted from oil solutions was very considerable and lie between 55 – 70 % . The change in the method of sulfonation caused a very clear change in the emulsion stability of the coolant fluids – lubrication , which contains one unit structure of composition and its percentage but they differ in the type of sodium sulfonate in it .
The sulfonation of base oil type 500 NS by sulfor trioxide lead to the production of highly efficient sulfonate to stabilize the emulsion of coolant fluids – lubrication as compared by the method of with oleum .
this difference in the efficiency of sulfonate may be due to the change in the chemical structure of produced sulfonic acids , that is the produced sulfuric acid from the sulfonation with sulfor trioxide consist basically of acids that are soluble in oil , whereas by using oleum in the sulfonation some produced sulfonic acid are solube in water besides to oil.9,22
The presence of sulfonic acids that are soluble in water in the composition of sodium sulfonate introduced into the formation of the emulsified coolant fluids – lubrication led to a decline of the emulsion stability . This conclusion was approved by using heavy base oils ( BSS ) ,these contain normally hydrocarbons of high aromatically .
The sulfonation of these hydrocarbons produce water – soluble sulfonic acids,9 and as shown in table (5 ) , the sulfonation of this type of oil by oleum lead to a decline in the emulsion stability .
The petroleum base oil of the type NS 500 and the dynamic poise = p= 10-1 Pa.S viscosity II centistokes at 100 C◦ was used for this work . The chemical structure of this oil was identified by absorptive chromatography method on silica – gel . This oil was eluted by different solutions such as hexan , benzene and ethanol respectively.7 The hydrocarbon groups were separated according to the fraction as following [ no 20 ].
Parrafins – Naphthenes from 1.74 to 1.49
Monocylic aromatic hydrocarbons from 1.49 to 1.51
Bicyclic aromatic hydrocarbon from 1.51 to 1.53
Polycyclic aromatic hydrocarbons was greater than 1.53 .
According to the previous mentioned method the chemical structure (% w) for base oil was as following:
Paraffin – naphthens (67.65); Monocyclic aromatic hydrocarbons (13.80); Bicyclic aromatic hydrocarbons (17.50); Polycyclic aromatic hydrocarbons (0.05).
Two methods have been used for sulfation : in the first method . Oleum containing 30 % SO3 by weight was used . The oleum was added slowly over 30 minutes with stirring at certain temperature . In the second method , the SO3 diluted with nitrogen ( approximate 4 % by volume ) was used . The excess SO3 oof was librated by heating the oleum and passing current of nitrogen . The sulfating agent (SO3 diluted with nitrogen ) was passed through the gas distributor placed in bottom of reactor that contains oil . this was within + 2 C◦. by heating the reactor , by using sulfation in this way , the unreacted residual gas was expelled at the end of reaction of reaction by heating to 70 C◦ .
The reaction depth was determined by measuring the content of reacted SO3 gas and also by measuring the acidity of the resulted sulfated oil . The stability of the emulsion versus , the time was also studied four hours , representing and the percentage of separated water was standard of the emulsifier stability .
Methods Of Characterization And Extraction
Acidity of sulfonated oil :
The acidity of sulfonated oil was determined by titration with standard solution of KOH.21 The sulfated oil ( 1 g ) was dissolved in mixture ( 100 cm3 ) of touluen and isopropyl alcohol in ration of 2:1 V/ V at high temperature .
Acidity ( mg KOH / g ) =
Extraction Method Of Petroleum Sulfonate
Neutralization of sulfonated petroleum base oil was carried out by 10% of sodium hydroxide ( NaOH ) at 50 C◦ in the presence of isopropyl alcohol.1 After addition of the hexane to the product , three layers were formed the upper layer was the unreacted base oil with hexane , and the middle layer was sodium sulfonate in isopropyl alcohol , and the lower layer was sodium sulfate with water .
The product of petroleum sulfonate was obtained from the extracted sulfonate layer vaporization of isopropyl alcohol .
Characterization Of Sulfonate
The extracted petroleum sulfonate was characterized by the above method and the percentage of pure sodium sulfonate and its oil content was determined.
The method depends upon the principle of the adsorptive chromatography on silica – gel.21 The column was prepared from the slurry of silica – gel in chloroform . The chloroform was eluted through the column to reach certain volume above silica gel level . The sodium sulfonate was dissolved in certain volume of chloroform and then added to silica gel column and left to diffuse through the separation column . both sulfonate and oil were eluted respectively with chloroform and ethanol and eventually , the products were obtained after getting ride of solvents by evaporization .
Formation Of Coolant Fluids
The coolant fluids were obtained according to the method13 from the extracted sulfonate by mixing 30 % of sodium sulfonate 60 % base oil 5 % Oleic oil and 5 % triethylamine . The produced compound was dissolved in 3 % water to form the coolant fluid as hydrate emulsion the stability of this emulsion was examined by this technique . Certain volumes of the emulsion transferred to separatory funnel and left for 24 hour then the upper oil layer was separated and purified from the impurities by the dissolving it in methylene chloride and water . After shaking , two layers were formed , and then the ethylene chloride layer was separated and finally the desired product was isolated and the yield which represents the emulsion stability of the coolant fluid was calculated .
1- The sulfonation of petroleum base oil of high viscosity ( 11 cent is took at 100ْ C ) was studied by both oleum and gaseous sulfur trioxide and the petroleum sodium sulfonate was extracted from the produced oil solutions .
2- The yield of pure sulfonates and the oil decrease after extraction with the increase of the isopropyl alcohol concentration in the produced extraction factor from the isopropyl alcohol and water . However the yield factor of sulfonate was found increases with increase of isopropyl alcohol concentration in water .
3- The highest yield factor of sulfonate was found 95.5% when the concentration of isopropyl alcohol was 65 % which is twice of sulfonated base – oil .
4- The stability evaluation results of coolant fluids -lubrication of the emulsifier type where the prepared petroleum sodium sulfonate was introduced in its composition by different methods showed the change in the method of sulfonated base oil lead to obvious change in the stability of these fluids.
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