EP0835298B1 - Alkaline treatment method for refining used oils - Google Patents

Abstract

PCT No. PCT/FR96/00974 Sec. 371 Date Apr. 20, 1998 Sec. 102(e) Date Apr. 20, 1998 PCT Filed Jun. 21, 1996 PCT Pub. No. WO97/00928 PCT Pub. Date Jan. 9, 1997An alkaline treatment method for refining used oils, wherein (a) the used oils are distilled; (b) the resulting distillate is treated with an alkaline agent in the presence of a solvent selected from water, a monoalcohol, a polyalcohol and a mixture of said a alcohols, said alkaline agent being present in a percentage by weight, based on the weight of the distillate, equal to the product Fx(IA+IS), where F is a multiplier between 2 and 50 and IA and IS are the acid value and the saponification value respectively of said distillate, at a temperatue of around 80-330 DEG C. for 2-200 minutes; (c) the reaction medium is washed with water then decanted to recover the oily phase; and (d) said oily phase is distilled. The method is useful for producing refined oils having excellent properties in that they are odorless and nearly colorless and in that they have a very low chlorine, phosphorus and sillicon content.

Description

The present invention relates to a process for refining used oils allowing refined oils to be reused, in particular as base oil, as fuel, or in an oil refinery.

According to the present application, the expression used oils means an oil or a mixture of oils in variable proportions, of various origins notably industrial applications.

As is well known, oils intended for industrial uses or for engines contain various additives intended to give them specific properties required for the intended applications. These additives are either organic (so-called additives "ashless") or organometallic. In all cases they are characterized, besides their specific function (such as anti-corrosion, anti-wear, antioxidant, dispersant ...) by a very good solubility in base oils (hydrocarbons with boiling points higher than 350 ° C), thermal stability as high as possible and finally volatility as low as possible.

Oils after use or used oils contain as impurities of such additives, either intact or in the form of decomposition products as well as sediment (wear particles from moving metal parts, air dust, carbon, etc.) and hydrocarbons not present in the original oils and which are undesirable. These are petrol and diesel fractions, oxidation products (such as organic acids) and pyrolysis products. The presence of these different impurities makes refining used oils particularly difficult.

Generally, industrial used oils as defined above have the characteristics given in Table I below: Chlorine content (mg / kg) 150-2000 Phosphorus content (mg / kg) 300-1300 Silicon content (mg / kg) 8-80 Color (ASTM D 1500) > 8 Odor (sensory measurement) Strong-very strong Water content (% by weight) 0.2-12 Sediments (% by weight) 0.1-0.5 Viscosity at 40 ° C (mm ² / s) 35-140 Acid number (IA; mgKOH / g) 0.9-4.5 Saponification index (IS; mgKOH / g) 4-17

In Table I above, the phosphorus and silicon contents have been measured by plasma, the chlorine contents either by X-ray fluorescence (above 50 mg / kg) either by coulometry (below 50 mg / kg), the acid number was determined according to the French standard NFT 60112, the viscosity was measured at 40 ° C according to the method NFT 60100, color was measured according to ASTM D 1500 method, odor was sensory measured by the experimenter and the saponification index was measured by potentiometry.

In order to separate the main contaminants from used oils, and to improve color and odor, several physical separation treatment methods and / or chemical and refining processes have been developed, with the aim of regenerate them and reuse them as base oil, as fuel, or in a oil refinery.

When these are intended to serve as base oils they must have very low coloration (at least less than 4 when measured according to ASTM standard D 1500).

When they are intended to be used as fuel, for example in industrial heating systems, they must be odor-free and have a low acidity (i.e. an IA acid number of less than about 0.2 mgKOH / g) as well as a low chlorine content, source of combustion pollutants.

Finally, when they are intended to be processed in an oil refinery (catalytic cracking or hydrogenation) they must have a very reduced rate in phosphorus, chlorine and silicon to prevent destruction of the catalysts (i.e. preferably a phosphorus content of less than 5 mg / kg, a chlorine content of less than 35 mg / kg and a silicon content of less than 5 mg / kg).

Among the known processes for the preliminary treatment of waste oils by physical separation, one can quote the vacuum distillation, the precipitation using a solvent such as propane (or "deasphalting") or ultrafiltration. These processes have a certain effectiveness in separating sediment and to some extent demetallizing or clarify used oils. Such physical pre-treatment methods do not allow however, to separate all the impurities present in the used oils. So by example, after distillation, the oils obtained still have a very strong odor, an acidity significant and contain significant amounts of volatile compounds, chlorine, phosphorus and silicon.

Among the known methods of prior treatment by chemical separation, there are may in particular cite those using an alkaline agent. However, these processes most of which are intended to facilitate the coagulation of the sediments and their separation, are essentially aimed at improving the performance of equipment (distillation, and exchangers by reducing their fouling). Here again, oils are obtained which are completely unsuitable for use as base oil to formulate new lubricants. So for example, alkaline treatments applied to waste oils before their vacuum distillation, if they effectively reduce the odor and acidity of the resulting oils, however do not eliminate quantitatively undesirable contaminants such as chlorine taking into account conditions under which alkaline agents are used.

From the used oils thus pretreated, they can be refined according to various processes in particular by catalytic hydrogenation at high pressure, or by treatment with concentrated sulfuric acid, by treatment with an activated earth or by the combination of these last two treatments and in some cases by distillation after one of these treatments.

However, high pressure catalytic hydrogenation cannot be used without raise catalyst deactivation problems if oils subjected to this type of are not rigorously free of contaminants such as phosphorus, chlorine and silicon. Treatment processes based on sulfuric acid / activated earth lead to the production of acid sludge and used earth which is difficult to absorb.

FR-A-2552098 décrit un procédé de retraitement d'huiles usées comprenant les étapes consistant à éliminer l'eau et les constituants volatils, puis à procéder à un traitement alcalin préalable à la distillation totale sous vide, lors de laquelle on sépare la fraction goudron.

FR-A-2302335 décrit un procédé de traitement d'huiles minérales usagées dans lequel on procède à une "épuration intense" de l'huile à traiter avant une étape d'hydrogénation comme étape de finition du procédé.

FR-A-2152821 décrit un procédé pour régénérer un lubrifiant non-aqueux pour le travail des métaux (par exemple le laminage à froid), ce procédé comprenant l'étape consistant à mettre en contact le lubrifiant avec un hydroxyde d'un métal alcalin en présence d'un monoalcool aliphatique, suivi de préférence d'une opération de séparation mécanique de manière à éliminer le précipité formé, par exemple une filtration ou une centrifugation.

As state of the art as mentioned above, the following patents may be mentioned in particular:

FR-A-2552098 describes a process for the reprocessing of used oils comprising the stages consisting in removing the water and the volatile constituents, then in carrying out an alkaline treatment prior to total distillation under vacuum, during which the fraction is separated tar.

FR-A-2302335 describes a process for treating used mineral oils in which an "intense purification" of the oil to be treated is carried out before a hydrogenation step as a step in finishing the process.

FR-A-2152821 describes a method for regenerating a non-aqueous lubricant for metalworking (for example cold rolling), this method comprising the step of bringing the lubricant into contact with an alkali metal hydroxide in the presence of an aliphatic monoalcohol, preferably followed by a mechanical separation operation so as to eliminate the precipitate formed, for example filtration or centrifugation.

The known processes for refining used oils therefore have poor performance or difficulties in removing by-products. There was therefore a definite need for the development of a process making it possible to obtain, so simple and economical, from used oils, refined oils with all the qualities and properties required.

a) à procéder à une distillation desdites huiles usagées,

b) à traiter le distillat résultant avec un agent alcalin et en présence d'un solvant choisi parmi l'eau, un monoalcool, un polyalcool et un mélange de ces alcools, ledit agent alcalin étant présent en une proportion, en pourcentage en poids par rapport au poids du distillat, égale au produit F x (IA+IS), F étant un facteur multiplicateur compris entre 2 et 50, IA et IS étant respectivement l'indice d'acide et l'indice de saponification du distillat, ledit traitement étant effectué à une température d'environ 80 à 330°C et pendant un temps d'environ 2 à 200 mn,

c) à laver à l'eau le milieu réactionnel puis à laisser décanter pour récupérer la phase huileuse, et

d) à procéder à la distillation de ladite phase huileuse.

The present invention thus relates to a process for refining used oils which makes it possible to obtain refined oils capable of meeting the various criteria of quality and purity set out above, this process being characterized in that it comprises a determined sequence of steps consisting of:

a) to carry out a distillation of said used oils,

b) treating the resulting distillate with an alkaline agent and in the presence of a solvent chosen from water, a monoalcohol, a polyalcohol and a mixture of these alcohols, said alkaline agent being present in a proportion, in percentage by weight per relative to the weight of the distillate, equal to the product F x (IA + IS), F being a multiplier between 2 and 50, IA and IS being respectively the acid index and the saponification index of the distillate, said treatment being carried out at a temperature of about 80 to 330 ° C and for a time of about 2 to 200 min,

c) washing the reaction medium with water and then leaving to settle to recover the oily phase, and

d) distilling said oily phase.

The method according to the invention has in particular the advantage of being very flexible insofar as it can be adapted, as regards its characteristics, to the quality required of finished products. In particular, the method according to the invention can be implemented following one or more preliminary, physical and / or chemical treatment processes, and / or upstream of one or more refining processes, such as those mentioned above.

According to a particular embodiment of the method according to the present invention, the distillation stage (a) is firstly carried out at atmospheric pressure, at a temperature of about 130 to 180 ° C, to remove water and recover a fraction of gasoline. The distillation is then continued, under a pressure of about 650 to 12,000 Pa and at a temperature of around 240 to 345 ° C, to recover a small fraction of diesel then a large fraction, greater than 60% of the used waste oil. Although the whole distillate can be subjected to the subsequent step, preferably used according to the invention, the only significant fraction of the distillate.

This pre-distillation step is particularly important because it eliminates almost all tar.

The alkaline agent used in step (b) of the process is either sodium hydroxide or potash but never a mixture of soda and potash. Preferably, according to the invention, potash. Given the proportion of alkaline agent added indicated above, the pH of the reaction medium (distillate + solution of alkaline agent) is greater than 8 and preferably between 9.5 and 13.

When the solvent used in step (b) of the process is water, the concentration of the alkaline agent in aqueous solution is preferably between 50 and 96% by weight relative to the weight of the aqueous solution. Advantageously, the aqueous solution of alkaline agent is in the form of eutectic potash / water (86.7 / 13.3).

The aqueous solution of alkaline agent is prepared beforehand and is then added with continuous stirring to the distillate resulting from step (a). It can be "solid" at the ambient temperature, as is particularly the case for the potash / water eutectic (86.7 / 13.3), the use of which constitutes a particularly preferred embodiment. In this in this case, the "solid" solution becomes fluid at the reaction temperature.

When the solvent used in step (b) is a monoalcohol, a polyalcohol or a mixture of these, the alcoholic solution used is preferably such that the ratio molar of said solvent to said alkaline agent is between 2 and 20, and more particularly between 2.5 and 5.

According to a preferred embodiment of the invention, an amount is used alcohol or a mixture of alcohol sufficient to ensure in the reaction medium alkaline agent concentration close to saturation.

The monoalcohol or the polyalcohol preferably contains from 2 to 8 atoms of carbon, and more particularly from 2 to 5 carbon atoms.

Among the monoalcohols preferred according to the invention, mention may be made of ethanol, n-propanol, isopropanol, n-butanol, sec-butanol, tert-butanol, isobutanol, pentanols, hexanols and octanols. Among the preferred polyalcohols according to the invention, may include ethylene glycol, di- and tri-ethylene glycol. According to the invention, it is preferred to use alcohols with a boiling point below the initial boiling point of the distillate and / or having a high solubility in water because their subsequent elimination by distillation or washing with water is easier

The reaction medium is preferably prepared either by dissolving the alkaline agent in alcohol, then introduction into the distillate, either by hot mixing of distillate and alcohol then addition of the alkaline agent in the form of solid tablets.

According to a particular embodiment of step (b) of the method according to the invention, when an alcohol or a mixture of alcohols is used as solvent, the treatment of the distillate with the alkaline agent is carried out at the reflux of the alcohol or of the mixture of alcohols provided, however, that there is no risk of loss by evaporation.

According to another particular embodiment of step (b) of the process according to the invention, when operating at high temperature, and in particular when the solvent comprises an alcohol with a boiling point below the reaction temperature chosen, the distillate is treated with the alkaline agent at a pressure of approximately 10 ⁵ to 50 x 10 ⁵ Pa, preferably at a pressure of 10 ⁵ to 25 x 10 ⁵ Pa, in order to avoid losses by evaporation.

At the end of the alkaline treatment, at least one washing of the medium is carried out reaction using approximately 1 to 15% of water at a temperature between room temperature and around 100 ° C. The water washing operation or step (c) of the process according to the invention makes it possible to remove the excess of alkaline agent, possibly the alcohol if this was used as a solvent as well as all the soluble products from contaminants and generated by alkaline treatment.

When the step of washing with water is carried out in a single operation, the latter is generally carried out using approximately 10% water at a temperature of approximately 100 ° C.

However, according to a particularly preferred embodiment, the step of washing is carried out in two separate operations. The first is to treat the environment reaction obtained after step (b) with an amount of water of about 1 to 10% and at a temperature as low as possible, between 20 and 90 ° C. The second is, after decanting, treating the reaction medium again with an amount of water included between 1 and 10% and at a temperature as high as possible and at least equal to that of the first operation.

According to the first washing operation, the temperature should preferably be the as low as possible in order to minimize the hydrolysis phenomena but sufficient to lower the viscosity of the oily reaction medium of step (b) and guarantee a speed of sufficient settling.

However, for the second washing operation, the temperature must be the as high as possible to ensure good removal of the residual alkaline agent.

The total amount of water used according to this particular form of achievement is preferably between 5 and 15%.

According to a variant of this washing step in two separate operations, the second washing operation can be carried out using a weak aqueous solution acid for example by means of hydrochloric acid 0.1 to 1 N.

After the washing and decanting stage of the oily phase, this is then subjected to the distillation step (d) consisting initially of a distillation at atmospheric pressure and at a temperature of about 70 to 270 ° C, to remove the rest solvent, then at a pressure of around 1350 to 650 Pa and at a temperature about 210 to 375 ° C in order to obtain a refined oil and a residue which represents less 5% of the initial charge.

According to a variant of the method according to the invention, step (c) of washing with water the oily phase can be followed by at least one treatment of said oily phase with high pressure catalytic hydrogenation by contact with a sulfonating agent and / or by contacting with activated carbon or an activated earth.

Preferably, the sulfonating agent is chosen from concentrated sulfuric acid and chlorosulfonic acid.

The activated earth is preferably a mineral earth of the silico-aluminate type activated by acid treatment.

In the case of treatment of the oily phase by contact with an agent sulfonating, this treatment is preferably followed by neutralization of the oily phase, by example by adding the washing water from step (c) and, preferably, by adding of ammonia.

The refined oil or the base oil obtained by the process according to the invention has excellent physical and chemical properties. She is practically odorless, weak in color and has very low chlorine contents, but also in phosphorus and silicon.

The main characteristics of the refined oils obtained by the process according to the invention are as follows: Chlorine content (mg / kg) <35 Phosphorus content (mg / kg) <5 Silicon content (mg / kg) <5 Color (ASTM D 1500) <3 Odor (sensory measurement) Very weak Water content (% by weight) <10 ^-2 Sediments (% by weight) Absence Viscosity at 40 ° C (mm ² / s) <85 Acid number (IA; mgKOH / g) <0.05 Saponification index (IS; mgKOH / g) <0.20

As can be seen by comparing Tables I and II, the method of treatment according to the invention is particularly effective in reducing the main contaminants of used oils.

We will now give by way of illustration several examples of implementation. work of the process according to the invention, from used oils whose characteristics have was previously given in Table I on page 1 of this description.

EXAMPLES 1 AND 2 :

From used oils of various industrial origins we first distilled at first under atmospheric pressure then, after temperature increase, under a pressure of about 1350 Pa.

This distillation made it possible to obtain the following fractions Fraction Pressure (Pa) Temperature (° C) Proportion (% by weight) 1 1.013 x 10 ⁵ 130/180 7.5% (water + petrol) 2 5300-10700 240/285 9% (diesel) 3 650-2000 285/345 65%

The distillation residue represented approximately 18.5% and was mainly made up of tars.

The fraction representing 65% had the following characteristics: Chlorine content (mg / kg) 60 Phosphorus content (mg / kg) 27 Silicon content (mg / kg) 9 Color (ASTM D 1500) 6.5 Odor (sensory measurement) Very strong Water content (mg / kg) <80 Sediments (% by weight) Absence Viscosity at 40 ° C (mm ² / s) 31.24 Acid number (IA; mgKOH / g) 0.26 Saponification index (IS; mgKOH / g) 1.30

A part of the distillate fraction representing approximately 65% was treated under the conditions given in Table V below using an aqueous potassium hydroxide solution at 50% by weight relative to the weight of the solution, at a temperature of 300 ° C and under a pressure of 14 x 10 ⁵ Pa and another part of this distillate using the potash / water eutectic (86.7 / 13.3), at a temperature of 220 ° C and at a pressure of 10 ⁵ Pa. After the alkaline treatment, the reaction medium was washed several times with water brought to a temperature of approximately 90 ° C. in order to remove the excess of alkaline agent and the different soluble products from alkaline treatment.

After separation of the oily phase, this was subjected to distillation first under atmospheric pressure then under a vacuum between 650 and 1350 Pa.

96% of the starting distillate was thus recovered.

The characteristics of the refined oils obtained are also given in Table V. As can be seen from these two processes by alkaline treatment lead to a refined oil having identical characteristics as to the decrease in phosphorus, silicon and chlorine contents.

It should however be noted that the pure potash to be used for reach the result is 7.2% or about 45 times the stoichiometry (IA + IS) if we uses a 50% and 0.47% aqueous solution of potash, or about three times the stoichiometry if the potash / water eutectic is used.

It is also important to note that in the latter case, the temperature of treatment is much lower since it is 220 ° C instead of 300 ° C.

We can therefore deduce a greater reactivity of the potash / water eutectic (86.7 / 13.3). EXAMPLES REACTIONAL CONDITIONS RESULTS (mg / kg) TEMP. ° C TIME min TITLE Sol. Aq. KOH P Yes Cl 1 300 30 50 7.2 1 <1 16 2 220 30 86.7 0.47 1 <1 16

EXAMPLES 3 TO 11 :

By following the same procedure of the process as described in the examples above and from the same distillate, step (b) of the alkaline treatment was used of the process according to the invention at temperatures varying between 175 and 300 ° C for a duration from 10 to 60 minutes with n-octanol under the conditions indicated in Table VI below.

The amount of alkaline agent used was in all cases at least equal to twice the stoichiometry (IA + IS) and all the tests according to these examples were carried out under atmospheric pressure with the exception of examples 10 and 11 which were carried out under a pressure of 10 × 10 ⁵ Pa.

It follows from Table VI that at equal temperature, the potash leads to more satisfactory results as regards the reduction in phosphorus, silicon and chlorine. Ex. TEMPERATURE ° C TIME min ALCOHOL ALKALINE AGENT RESULTS (mg / kg) Type % Mass Pure NaOH KOH P Yes Cl 3 175 10 nC ₈ H ₁₇ OH 4.4 - 0.49 5 2 32 4 200 60 nC ₈ H ₁₇ OH 3.24 - 0.36 3 <1 10 5 200 60 nC ₈ H ₁₇ OH 7.1 - 0.79 1 <1 8 6 200 60 nC ₈ H ₁₇ OH 19.3 - 2.14 1 <1 3 7 200 60 nC ₈ H ₁₇ OH 3.24 0.36 - 2 <1 18 8 200 60 nC ₈ H ₁₇ OH 7.1 0.79 - 2 <1 14 9 200 60 nC ₈ H ₁₇ OH 19.3 2.14 - 1 <1 12 10 250 30 nC ₈ H ₁₇ OH 7.7 - 1.29 1 <1 20 11 300 60 nC ₈ H ₁₇ OH 7.2 - 0.79 1 1 5

EXAMPLE 12 :

From used oils of various origins, a distillate having the following characteristics was obtained, after distillation according to the technique of the previous examples: Chlorine content (mg / Kg) 72.00 Phosphorus content (mg / Kg) 18.00 Silicon content (mg / Kg) 23.00 Color (ASTM D 1500) 7.00 Acid number (IA; mg KOH / g) 0.49 Saponification index (IS; mgKOH / g) 2.90

Half of the distillate was treated with 2.5% 85% potash (i.e. 2% of dry potash) and the other half was treated with 4.71% 85% potash (i.e. 4% dry potash). The treatments were carried out at a temperature of 250 ° C for 30 about minutes.

The first half resulting from the treatment with 2% dry potash was divided into two equal parts.

(i) un premier lavage à l'aide de 5 % d'eau à 65°C et après décantation à

(ii) un deuxième lavage à l'aide de 5 % d'eau à 100°C.

The first was subjected to a single washing with 10% water at 100 ° C, and the second to the following two washing operations:

(i) a first wash using 5% water at 65 ° C and after decantation at

(ii) a second wash using 5% water at 100 ° C.

Likewise, the second half resulting from the treatment with 4% of dry potash was divided into two equal parts.

(i) un premier lavage à l'aide de 5 % d'eau à 65°C et après décantation à

(ii) un deuxième lavage à l'aide de 5 % d'eau à 100°C.

The first was subjected to a single washing with 10% water at 100 ° C, and the second to the following two washing operations:

(i) a first wash using 5% water at 65 ° C and after decantation at

(ii) a second wash using 5% water at 100 ° C.

After decantation, the four oily residues obtained were subjected to fractional distillation under a pressure of 1,300 Pa with a view to obtaining for each of them the following four fractions (corrected temperatures reduced to 1 Atm) Fraction I 264 - 370 ° C Fraction II 370 - 441 ° C Fraction III 441 - 475 ° C Fraction IV 475 - 558 ° C

The colors of the various fractions obtained were then measured according to the ASTM D 1500 method and the results are collated in Table VII below. KOH dry 2% 4% Fractions I II III IV I II III IV H ₂ O wash 1 operation 2.5 1.5 <2.5 <3.5 1.5 <3 <4 <6 2 operations <1.5 <1.5 <1.5 <3.5 <1 <1 <1.5 3.5

As can be seen, washing in two operations leads to oils with a markedly improved color which is a result particularly unexpected.

It has also been found that in order to optimize the yields of products oily before the distillation stage, it was advisable to use in the washing process in two operations, a quantity of water during the first wash, greater than or equal to 2% but less than or equal to 10% and preferably between approximately 4 to 6% in order to obtain yields of the order of 90 to 98%.

Claims (14)

1. Process to refine used oils containing various contaminants, characterized by the fact it involves successive steps consisting in

   a) performing a fractional distillation of said used oils in order to recover a fraction at a temperature between approximately 240 and 345 °C, under a pressure between approximately 650 and 12000 Pa;

   b) processing the said fraction obtained with an alkaline agent selected between sodium hydroxyde or potassium hydroxyde and in the presence of a solvent selected among water, a monoalcohol, a polyalcohol and a mixture of these alcohols, said alkaline agent being present in a proportion (weight for 100 weight distillate) defined as F × (IA + IS), F being a factor between 2 and 50, IA and IS being acid and saponification numbers respectively of the distillate, said processing being performed at a temperature between approximately 80 and 330 °C for a time between approximately 2 and 200 minutes;

   c) washing the reacted medium with 1 to 15 % water at a temperature between ambient and approximately 100 °C, then settled to recover the oil phase and

   d) submit it to fractional distillation under a pressure between approximately 1350 and 650 Pa, at a temperature between approximately 210 and 375 °C in order to recover the refined oil fraction.
2. Process according to claim 1 whereby the alkaline agent is potassium hydroxyde.
3. Process according to any of the above claims whereby the solvent is water, the alkaline agent concentration between 50 and 96 % wt on the aqueous solution.
4. Process according to any of the above claims whereby the alkaline agent is the potassium hydroxyde/water eutectic (86.7/13.3).
5. Process according to claim 1 or 2 whereby when the solvent is selected among a monoalcohol and a polyalcohol or a blend, the alcohol/alkaline agent mole ratio is between 2 and 20.
6. Process according to claim 5 whereby the said mole ratio is between 2.5 and 5.
7. Process according to any of 1, 2, 5 and 6 claims whereby the said mono or polyalcohol has between 2 and 8 carbon atoms.
8. Process according to any of the above claims whereby the step c) (water washing of the reacted medium) is performed as two successive operations, the first one consisting in washing with 1 to 10 % water at a temperature between approximately 20 and 90 °C and the second one consisting, after settling, in washing the resulting medium with 1 to 10 % water at a temperature as high as possible and at least equal to that of the first step.
9. Process according to claim 8 whereby the second washing operation is performed with a weak acidic aqueous solution.
10. Process according to any of the above claims whereby the oily phase from the washing step c) is followed by at least high pressure catalytic hydrogenation and/or contacting with a sulfonating agent, activated carbon or activated clay.
11. Process according to claim 10 whereby the sulfonating agent is selected among sulfuric acid and chlorosulfonic acid.
12. Process according to claim 10 whereby the activated clay is an acid treated silicoaluminate.
13. Process according to claim 10 whereby contacting the oily phase with a sulfonating agent is followed by neutralization of the oily phase.
14. Process according to claim 13 whereby the said neutralization of the oily phase is performed with aqueous ammonia.