REMOVAL OF NAFETY ACIDS IN RAW AND DISTILLED OILS
FIELD OF THE INVENTION The present invention relates to the removal of organic acids, heavy metals and sulfur in crude oils, mixtures of crude oils as well as distillates of crude oils by the use of a specific class of compounds. BACKGROUND OF THE INVENTION Crude High Total Acid Number (TAN) receive a discount of approximately $ 0.50 / TAN / BBL. What drives downstream businesses towards the development of technologies for the reduction of TAN is the ability to refine low-cost crude. What drives upstream business is to improve the market value of crude containing high contents of TAN, metals and sulfur. The current approach to refine acidic crudes is to mix the acidic crudes with non-acidic crudes in such a way that the TAN of the mixture is not greater than about 0.5. Most major oil companies use this approach. The drawback of this approach is that it limits the amount of acid crude that can be processed. Furthermore, it is known in the art to treat the crudes with inorganic bases such as potassium hydroxide and sodium to neutralize the acids. However, this approach forms emulsions that are very difficult to break and, in addition, leave undesirable potassium or sodium in the treated crude. In addition, said prior techniques are limited by the range of molecular weights of the acids that can be removed. With the projected increase of acidic crudes in the market (Chad, Venezuela, North Sea), new technologies are required to further refine crude with a higher TAN and crude mixtures. Heat treatment, hydroprocessing of pastes and neutralization with calcium are some of the promising approaches that have emerged. However, these technologies do not extract acids, metals or sulfur from crude ones. Instead, they convert the acids into products that remain in the crude. In the same way, the removal of heavy metals, for example, organ vanadium compounds and nickel and sulfur is desirable to avoid fouling the catalyst during the improvement and to solve environmental problems. U.S. Patent No. 4,752,381 focuses on a method for neutralizing organic acidity in petroleum and petroleum fractions to produce a neutralization number of less than 1.0. The method includes treating the petroleum fraction with a monoethanolamine to form an amine salt followed by heating for a time and at a temperature sufficient to form an amide. Such amines do not provide the desired results in the present invention since they convert the naphthenic acids into other products, while the present invention extracts the naphthenic acids. US Patent No. 2,424,158 focuses on a method for the removal of organic acids from crude oils The patent employs a contact agent which is an organic liquid Suitable disclosed amines are monoethanolamine, diethanolamine and triethanolamine, as well as methylamine, ethylamine , n- and isopropylamine, n-butylamine, sec-butylamine, tert-butylamine, propanolamine, isopropanolamine, butanolamine, sec-butanol, sec-butanolamine, and tert-butanolamine COMPENDIUM OF THE INVENTION The present invention focuses on a process for extracting organic acids including naphthenic acids, heavy metals, and sulfur from an initial crude comprising the steps of: (a) treating the initial crude oil containing organic acids, heavy metals, and sulfur with an amount of an ethoxylated amine and low water conditions and for a time and at a temperature sufficient to form an emulsion of water in amine salt oil where said ethoxylated amine It has the following formula:
R-N- (CH2CH20) mH
H where m = 1 to 10 and R = hydrocarbon C3 to C6; (b) separating said emulsion from step (a) in several layers, where one of these layers contains a treated crude oil having decreased amounts of organic acids, heavy metals and sulfur; (c) recovering said layer of step (b) containing said treated crude oil having decreased amounts of organic acids, heavy metals and sulfur and layers containing water and salt of ethoxylated amine. The present invention may comprise, consist or consist essentially of the elements disclosed herein and may be practiced in the absence of an undisclosed element. BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a flow diagram showing how the process can be applied to existing refineries. (1) it is water and ethoxylated amine, (2) it is crude crude oil, (3) it is the desalination unit , (4) is the unit of regeneration,
(5) is the organic acid conversion unit, (6) is a treated crude from which organic acids have been removed, (7) is a lower phase emulsion, and (8) is a product. Figure 2 is a flow chart showing the application of the present invention at the wellhead .. (1) is a full well current, (2) is a primary separator, (3) is gas, (4) it is crude, (5) it is crude treated (improved), (6) it is water and organic acid, (7) it is a contact tower, (8) it is an ethoxylated amine and (9) it is water. Figure 3 is an apparatus that can be used to recover the ethoxylated amines that have been used to remove naphthenic acids from an initial crude. (1) is a layer or phase containing ethoxylated amine, (2) is a thermometer, (3) is a vent, (4) is a graduated column to measure foam height, (5) is a gas distributor, (6) is gas, (7) is where the foam breaks, and (8) is where the recovered ethoxylated amine is collected. DETAILED DESCRIPTION OF THE INVENTION In the present invention, ethoxylated amines of the following formula are added R-N- (CH2CH20) mH
H to an initial crude oil to remove organic acids, heavy metals, for example, organ vanadium and nickel compounds, and sulfur. Some crude oils contain organic acids that generally fall into the category of naphthenic acids and other organic acids. Naphthenic acid is a generic term used to identify a mixture of organic acids present in a petroleum raw material. The naphthenic acids may be present either alone or in combination with other organic acids such as sulfonic acids and phenols. Thus, the present invention is particularly suitable for the extraction of naphthenic acids. The important characteristics of the ethoxylated amines are that the alkyl groups are such that the amine can be mixed in the oil to be treated, and that the ethoxylated groups provide water solubility to the salts formed. In the above formula, m is from 1 to 10, preferably from 1 to 5, R = hydrocarbon C3 to C. R can be linear or branched. For example, suitable R groups are tertiary butyl, tertiary amyl, neopentyl, and cyclohexyl, preferably R will be tertiary butyl and m will be 2. Surprisingly, a primary amine (R = H), even when soluble in water and a strong base does not remove organic acids, including naphthenic acids according to what is described in the present invention. In the present invention, organic acids, including naphthenic acids removed from the initial crude oil or initial mixtures are preferably those having molecular weights within a range of from about 150 to about 800, more preferably from about 200 to about 750. The present invention, preferably substantially removes or substantially decreases the amount of naphthenic acids present in the initial crude. By substitution is meant all the acids except trace level quantities. However, it is not necessary to remove substantially all the acids since the value of the treated crude is increased even when only a part of the naphthenic acids is removed. Applicants have found that the amount of naphthenic acids was reduced by at least about 70%, preferably at least about 90% and, more preferably, at least about 95%. The amount of heavy metals can be reduced by at least about 5%, preferably at least about 10% and, more preferably, by at least about 20%. The amount of sulfur can be reduced by at least about 5%, preferably about 10%, and, more preferably, about 17%. Particularly vanadium and nickel will be reduced. The initial crude oils (initial crudes) as used herein include blends of crude and distillates. Preferably, the initial crude is a whole crude, but it can also be acid fractions of a whole crude oil, such as vacuum gas oil. The initial crudes are treated with an amount of ethoxylated amine capable of forming an amine salt with the organic acids present in the initial crude. This will be the amount needed to neutralize the desired amount of acids present. Typically, the amount of ethoxylated amine will be within a range of about 0.15 to about 3 molar equivalents based on the amount of organic acid present in the crude. If one wishes to substantially neutralize all the naphthenic acids present, then a molar excess of ethoxylated amine will be employed. The amount of naphthenic acid present in the crude oil will preferably be used 2.5 times. The molar excess allows the removal of acids with higher molecular weights. The present invention can remove naphthenic acids within a range of molecular weights from about 150 to about 800, preferably from about 250 to about 750. The weight ranges for the naphthenic acids removed can vary up or down from the numbers presented. here since the ranges depend on the level of sensitivity of the analytical means used to determine the molecular weights of the naphthenic acids removed. The ethoxylated amines can be added alone or in combination with water. If they are added in combination, a solution of the ethoxylated amine and water can be prepared. Preferably, about 5 to 10% by weight of water is added based on the amount of crude oil. If the amine is added in combination with water or before water, the crude oil is treated for a period and at a temperature such that a water-in-oil emulsion of ethoxylated amine salts of organic acids is formed. Times vary according to the nature of the initial crude to be treated, its acid content, and the amount of ethoxylated amine added. The temperature of the reaction is any temperature that effects the reaction of the ethoxylated amine and the naphthenic acids contained in the crude to be treated. Typically, the process is carried out at temperatures of from about 20 to about 220 ° C, preferably from about 25 to about 130 ° C, and more preferably from about 25 to about 80 ° C. The pressures are located within a range from approximately atmospheric pressure, preferably from about 60 psi and, more preferably, from about 60 psi to about 1000 psi. The contact times are within a range of about 1 minute to 1 hour, preferably from about 3 minutes to 30 minutes. The heavier crudes will be treated preferably at the higher temperatures and pressures. The crude containing the salts is then mixed with water, if a stepwise addition is carried out, at a temperature and for a sufficient time to form an emulsion. Times and temperatures remain the same for simultaneous addition and stepwise addition of water. If the addition is carried out simultaneously, the mixing is carried out simultaneously with the addition at the temperatures and during the times described above. It is not necessary for the simultaneous addition to mix during a period in addition to the period during which the salt formation is taking place. Thus, the treatment of the initial crude includes both contact and agitation to form an emulsion, for example, mixed. Heavy crudes, such as those with APIs of 20 or less and viscosities greater than 200 cP at a temperature of 25 ° C, will be treated preferably at temperatures above 60 ° C. Once the water-in-oil emulsion is formed, said emulsion is separated into several layers. The separation can be achieved through means known to those skilled in the art. For example, centrifugation can be used, settlement by gravity, and electrostatic separation. Several layers result from separation. Typically, three layers are produced. The top layer contains the crude oil from which the acids, heavy metals, and sulfur were removed. The middle layer is an emulsion containing ethoxylated amine salts of high and medium weight acids and organo vanadium and nickel surfactant compounds and sulfur compounds, while the bottom layer is an aqueous layer containing acid ethoxylated amine salts of low molecular weights. The upper layer containing the treated crude can be easily recovered as known to the person skilled in the art. Thus, unlike the treatment used in the past where the acids are converted into products that remain in the crude, the process of the present invention removes the acids from the crude. In addition, even when not required, de-emulsification agents can be used to improve the speed of demulsification and co-solvents, such as alcohols, can be employed together with the water. The process can be carried out using existing desalination units. Figure 1 shows the process of the present invention when applied in a refinery. The process can be applied to both production and refining operations. The acidic oil stream is treated with the required amount of ethoxylated amine by adding the amine to the wash water and mixing it with a low-cut static mixer. Alternatively, the ethoxylated amine can be added first, mixed and then water is added and mixed. The initial treated crude is then subjected to de-emulsification or separation in a desalination unit that applies an electrostatic or other separation medium. The initial treated crude is then subjected to de-emulsification or separation in a desalination unit that applies an electrostatic or other separation medium. Oil with a reduced TAN, a lower amount of metals and sulfur is removed at the top and subjected to additional refining if desired. The lower aqueous and emulsion phases are extracted together or separately, preferably together, and discarded. They can also be processed separately to recover the treatment amine. In the same way, the recovered aqueous amine solution can be reused and a cyclic process is obtained. The naphthenic acid stream can be further treated by methods known to those skilled in the art to produce a non-corrosive product, or it can also be discarded. In a production process, the present invention could be applied especially in the wellhead. At the wellhead, crude initials typically contain water and co-produced gases. Figure 2 illustrates the application capacity of the present invention in the well head. In Figure 2, a full well stream containing initial crude, water and gases is passed in a separator, and separated into a gas stream that is removed, a stream of water that may contain initial crude oil traces, and a stream of initial crude oil (with removal of water and gases) that may contain water footprints. The water and crude streams are then passed in a contact tower. Ethoxylated amine can be added to either the crude or the water and mixed and carried out the treatment of the present invention in the contact tower. The water and crude streams are passed countercurrent in the contact tower, in the presence of ethoxylated amine, to form an oil emulsion in unstable water. An unstable emulsion is formed by the addition of acidic crude oil with only slight agitation to the aqueous phase in a sufficient ratio to produce a dispersion of oil in a continuous aqueous phase. The crude must be added to the aqueous phase instead of adding the aqueous phase to the crude, in order to minimize the formation of a stable emulsion of water in oil. A ratio of 1: 3 to 1:15, preferably from 1: 3 to 1: 4 between oil and aqueous phase is used based on the weight of oil and aqueous phase. A stable emulsion will be formed if the ratio between the oil and the aqueous phase is 1 to 1 or less. The amount of ethoxylated amine will be within a range of about 0.15 to about 3 molar equivalents based on the amount of organic acid present in the initial crude. An aqueous phase is either the aqueous stream if ethoxylated amine is directly added to the raw or ethoxylated amine and water, if ethoxylated amine is added to the water. Typically, a small droplet size of 10 to 50 microns, preferably 20 to 50 microns, is required. The contact of the crude with the aqueous ethoxylated amine should last for a sufficient period to disperse the crude in the aqueous ethoxylated amine preferably to cause at least 50% by weight, more preferably at least 80% by weight and especially the 90% by weight of the oil is dispersed in the aqueous ethoxylated amine. The contacting is typically carried out at temperatures within a range of about 10 ° C to about 40 ° C. At temperatures above 40 ° C, the probability of forming a stable emulsion rises. The ammonium salts of naphthenic acid produced are removed from the small droplets of crude as they rise from the bottom of the contact tower. The treated crude is removed from the top of the contact torr and the water containing ethoxylated amine salts of naphthenic acids (lower layers) is removed from the bottom of the contact tower. In this way, an improved crude oil with naphthenic acid removal is recovered at the wellhead. The treated crude can be treated electrostatically to remove the remaining water and the remaining naphthenic acids if desired. The water and the byproducts of ethoxylated amine salt of organic acid removed from the contact tower can be injected back into the soil. However, due to the cost of the ethoxylated amine, it is desirable to carry out a recovery step before reinjection. The recovered ethoxylated amine can then be used again in the process, thus creating a cyclic process. If it is desired to regenerate the organic acids, including naphthenic acids and ethoxylated amines, the following process can be employed. The method comprises the steps of (a) treating the remaining layers after the removal of said treated crude layer including said emulsion layer, with an acid solution selected from the group comprising mineral acids or carbon dioxide, at a pressure and at a pH sufficient to produce naphthenic acids and an amine salt of said mineral acid when a mineral acid or an amine bicarbonate is used when carbon dioxide is used, (b) separating an upper layer containing naphthenic acids and a layer lower aqueous; (c) adding, to the lower aqueous layer, an inorganic base if step (a) employs a mineral acid, or heating at a temperature and for a sufficient time, if step (a) employs carbon dioxide to raise the pH a > 8; (d) blowing gas through said aqueous layer to create a foam containing said ethoxylated amines; (e) removing said foam to obtain said ethoxylated amines. The foam can be additionally collapsed or it will collapse with the passage of time. A gas can be used to create the foam provided that said gas is not reactive or is inert in the process of the present invention, however, air is preferably used. Those skilled in the art can easily select suitable gases. If it is desirable to collapse the foam, chemical agents known to those skilled in the art can be employed, or other known mechanical techniques. In the method used to recover the ethoxylated amines, a mineral acid can be used to convert any ethoxylated amine salt of naphthenic acid formed during the removal of naphthenic acid from an initial crude. The acids can be selected from sulfuric acid, hydrochloric acid, phosphoric acid and mixtures thereof. In addition, carbon dioxide can be added to the emulsion of ethoxylated amine salts under pressure. In any of the scenarios, the acid addition proceeds to a pH of about 6 or less, preferably a pH within a range of about 4 to 6. The addition of acid results in the formation of an upper layer of oil containing naphthenic acid and a lower aqueous layer. The layers are then separated and an inorganic base is added to the aqueous layer such as for example ammonium hydroxide, sodium hydroxide, potassium hydroxide or mixtures thereof, if a mineral acid is used, to obtain a pH greater than about 8. Alternatively, the aqueous layer is heated at a temperature and for a sufficient time, if carbon dioxide is used to obtain a pH greater than about 8. Typically, the layer will be heated to a temperature of about 40 to about 85 ° C, preferably a temperature of about 80 ° C. A gas, for example, air, nitrogen, methane or ethane, is then blown through the solution at a rate sufficient to create a foam containing the ethoxylated amines. The foam is then recovered and collapsed to obtain the ethoxylated amine. The recovery process can be used either in the refinery or in the wellhead before reinjection. The invention will now be illustrated by the following examples which are not intended to limit said invention. EXAMPLE 1: In this example a 40/30/30"ISOPAR-M" / Solvent 600 Neutral / Aromatic 150 was used as model oil. "ISOPAR-M" is an isoparaffinic distillate, Solvent 600 Neutral is a base oil, and Aromatic 150 is an aromatic distillate. 5-β-colanic acid was used as the model naphthenic acid and octaethylprorfirinvanadium oxide as the heavy metal. The acidic crude was treated with an equimolar amount (based on the amount of 5-ß-colic acid) of a secondary amine ethoxylate where R = t-butyl and m = 2. 5% by weight of water was added and the treated oil was mixed. The emulsion that was formed was centrifuged to separate the naphthenic acid as its salt and organ vanadium in an emulsion phase. In this example, 2% by weight of 5-ß-colic acid and 0.05% by weight of octaethylprorfirinvanadium oxide were solubilized in the model oil and subjected to the emulsion fractionation process described here (mixing for 15 minutes at room temperature) using tertiary butyldiethanolamine. The total acid number of the model oil dropped from 4.0 to 0.23, and a decrease of 23% was observed for octaethylvanadioprorphyrin oxide. High performance liquid chromatography revealed a 99% removal of the 5-ß-colic acid from the treated oil. EXAMPLE 2: A North Sea Crude (Gryphon) that has a TAN of 4.6 was used in this example. Tertiary butyldiethanolamine was employed in various amine treatment regimes and various percentages by weight of water addition. The results appear in table 1. TABLE 1 Molar ratio between amine and acid = 2.5 Mixing temperature = 25 ° C Mixing time = 5 to 30 minutes Volume of wash water = 5 to 10% by weight Washing water mixture = gentle agitation of oil / water mixture for 10 to 15 minutes Separation = centrifugation at 1800 revolutions per minute for 30 minutes or electrostatic demulsification at 80 ° C for 30 minutes Amine treatment regimen% by weight TAN from amine (water equivalents) because of molars) treatment
H 1.2 5 1.2
t-butyl-N- (EO) 2H H 2.5
t-butyl-N- (EO) 2H none 0 10 4.2
EXAMPLE 3: A Venezuelan crude oil was treated in accordance with that described in example 2 (2.5 molar equivalents of amine and 5% by weight of water) and a reduction of TAN from 2.2 to 1.1 was observed, a reduction of 13% in terms of to vanadium, and a 17% reduction in sulfur. The extraction temperature was 80 ° C, at atmospheric pressure and the time was 1 hour. An improvement in performance in terms of TAN reduction from 2.2 to 0.6 was observed when the extraction temperature was 180 ° C, the pressure 60 psi, and the time equal to 1 hour. EXAMPLE 4: A Chad Bolobo 2/4 crude having a TAN of 7.3, a viscosity of approximately 6000 cP at 25 ° C and 10 sec "1 and an API gravity of 16.8 was used in this example. the conditions presented in Example 3. A reduction in TAN from 7.3 to 3.9 was observed EXAMPLE 5: Regeneration of Amine Using Mineral Acid A crude from the North Sea, Gryphon, was subjected to the emulsion fractionation process described in Example 2 The lower emulsion phase was extracted and used in the following manner: 100 mL of the emulsion was taken in a separatory funnel and concentrated sulfuric acid was added to bring it to a pH of 6. A release of naphthenic acid was observed in the form of oil insoluble in water The lower aqueous phase was separated from the oil phase The oil phase was analyzed by FTIR and 13 CNMR to confirm the presence of naphthenic acids. two naphthenics with molecular weights of 250 to 750. Ammonium hydroxide was added to the aqueous phase to obtain a pH of 9. The aqueous solution was introduced into a foam generating apparatus illustrated in Figure 3. Air was bubbled through the Inlet tube in the bottom to generate a stable sustained foam collected in the collection chamber. The foam collapsed on standing which resulted in a yellow liquid characterized as a tertiary butyldiethanolamine concentrate. EXAMPLE 6: Regeneration of Amine Using C02 A crude from the North Sea, Gryphon, was subjected to the emulsion fractionation process described in Example 2. The lower emulsion phase was extracted and used as follows. 100 mL of the emulsion was taken in an autoclave, CO 2 was added and the emulsion was stirred at 300 rpm at a temperature of 80 ° C and under a pressure of 100 psi and for 2 hours. The product was centrifuged for 20 minutes at 1800 rpm to separate water-insoluble naphthenic acids from the aqueous phase. The aqueous phase was analyzed by FTIR and 13C NMR to confirm the presence of naphthenic acid. An HPLC analysis indicated the extraction of naphthenic acids of molecular weights between 250 and 750. The lower aqueous phase had a pH of 9 which indicates the regeneration of the organic amine. The aqueous solution was introduced into the foam generation apparatus illustrated in Figure 3. Air was bubbled through the inlet tube at the bottom to generate a stable sustained foam that was collected in a collection chamber. The foam collapsed on standing which resulted in a yellow liquid characterized as a tertiary butyldiethanolamine concentrate.