US3082167A - Process for removing metals from petroleum with an aromatic sulfonic acid - Google Patents

Description

U fll States Patem a.

3,082,167 PROCESS FOR REMOVING METALS FROM PETRO- LEUM WITH AN AROMATIC SULFONIC ACID John G. Erdman, Allison Park, Par, assignor to Gulf Research & Development Company, Pittsburgh, Pa., a corporation of Delaware N Drawing. Filed July24, 1961, Ser. No. 125,969 5 Claims.v (Cl; 208252) This invention relates to a process for treating mineral oils and more particularly to a process for reducing heavy metal contaminants especially the porphyrin metallo complex content of mineral oils.

Vanadium, nickel and traces of other metals including iron and copper have been detected in crude oils and in various petroleum distillates, some crude oils containing up to 1000 parts per million, or more, of vanadium. The presence of these metals in catalytic cracking charge stock is undesirable in that they adversely affect the effective life of crackingzcatalysts. These metals are undesirable in residual fractions used as fuel because of their tendency to cause corrosion and pitting of materials of construction with which they come in contact. For example,- thepresence-of vanadium in residual fuel oils results in corrosion and fouling of high temperature boilers and the blades and heat exchanger tubes of gas turbines.

A considerable portion of the metals selected from the group consisting of vanadium and nickel when pres ent in mineral oils, exist in the form of stable, volatile, non-ionic, oilesoluble, porphyrin metallo complexes. The porphyrin metal-lo complexes are believedto be the only volatile metallo complexes present in oils. The porphyrin metallo complexes can be illustrated by the fol-lowing structural formula where M is vanadyl (V=O) and nickelic (Ni).

The physical and chemical characteristics of the porphyrin metallo complexes coupled with their presence in mineral oils in small amounts, has rendered their removal from, oils containing them extremely difiicult.

Porphyrin metallo complexes occur in crude oils obtained from many geographic locations. In preparing distillates from such crude oils aportion of these complexes passesinto the products. It has been'ascertained that the porphyrin metallo complexes possess sufiicient volatility and thermal stability to distill over with petroleum fractions without decompositions. .Regardless of whether the porphyrin metallo complexes are introduced into the distillates by' distillation or entrainment their a presence is highly undesirable.

Because of their neutral and oil-soluble. character, the

\ .porphyrin metallo complexes of the type occurring in 3,082,167 Patented Mar. 19, 1963 are ineffective. The porphyrin complexes of vanadium and nickel are so stable thermally that their destruction without substantial modification of the oils in which they occur is difiicult. The aromatic hydrocarbon and nonhydrocarbon portions of crude oils and other petroleum stocks including distillates are adsorbed more readily than the porphyrin metallo complexes on polar adsorbents such as clay thus preventing removal of the complexes in this manner.

Attempts have been made to reduce the. porphyrin metallo complexes in catalytic cracking charge stocks by cutting the crude at temperatures below which the metallo complexes pass into the distillate. While such attempts to control the porphyrin metallo complexes in the distillates have been at least partially successful, the amount of cracking charge stock obtained from a crude oil is materially reduced.

I have now discovered that heavy metal contaminants including the porphyrin metallo complexes can be removed from a mineral oil containing such contaminants by treating the contaminated oil in the liquid phase at a temperature of about 100 to about 250 C. with an aromatic sulfonic acid which is liquid at the treating temperature. Under these conditions, the. aromatic sulfonic acidsform a complex with the heavy metal contaminants. The complex. thusformed and excess sulfonic acid settles from the oil in the form of a precipitate when the oil is cooled to room temperature or below. Upon separating the precipitate from the oil, an oil is obtained having a substantial reduction of heavy metal contaminants. Thus, the process of the invention elTectively removes heavy metal contaminants, such as vanadium and nickel including porphyrin inetallo complexes from a mineral. oil.

The aromatic sulfonic acids which can be employed in the process of the invention. are" the monoand polysulfonic acids of aromatic hydrocarbons and the monoandtpoly-sulfonic acids of the lower alkyl substituted aromatic hydrocarbons. Representative aromatic sulfonic acids-thus include' b'enzenesulfonic acid; p-toluenesulfonic acid; diand trisulfonic acids of. toluene; 0-, mand pxylene sulfonic acids; ethylbenzene sulfonic acids; mesi tylene sulfonic acid; and mono-, di-, triand tetrasulfonic acids'of naphthalene.

The present process isgenerally applicable to all types of metal-containing mineral. oils especially petroleum oils including both petroleum crude's and fractions thereof whether derived from pa'raflinic, naphthenic or asphalt base stocks which may contain up to 1000' parts per million or more of contaminating metal. Thus, the process can be applied not only to metal-contaminated crude petroleum oils and virgin-stocks obtained from crude distillation untis, but also to metal-contaminated products obtained from typical hydrocarbon conversion processes such as cataly-ticcracking, hydroforming, steam cracking, and coking. While the process of the invention can be applied both to petroleum residual fractions and overhead fractions or distillates, the process of the invention is particularly applicable to petroleum distillates.

In accordance with the present invention, substantial removal of'the heavy metal contaminants from a petroleum oil containing the same is eiiected by intimately contacting, the contaminated oil with the aromatic sulfoni c acid for a time and in an amount sufficient to form a complex between the aromatic sulfonic acid and a substantial portion of the heavy metals in the. oil at a temperature of about to about 250 C. A temperature of 100 .C. or more, is desirable in order to assure substantially anhydrous operating conditions. "The use of an anhydrous system is desirable in that the presencejof water tends to inhibit the reaction and thereby increase the amount of the sulfonic acid which must be used. The reaction mass is then cooled, usually to room temperature, whereupon the aromatic sulfonic acid-heavy metal complex readily precipitates from the oil. Separation of the precipitated complex from the oil can be effected by any known means such as, for example, by

1 filtration, decanting, centrifuging and the like.

The amount of the aromatic sulfonic acid employed is that amount which is at least sutficient to saturate the contaminated oil at the particular treating temperature employed. While the aromatic sulfonic acids are generally considered to be insoluble in oil, they are soluble to a small extent at room temperature and to a greater extent at temperatures of 100 to 250 C. Generally, amounts ranging from about 0.05 to about 1.0 weight percent based on the contaminated oil are sufficient to completely saturate the oil at temperatures of 100 to 250 C. While an amount greater than that which is soluble in the oil can be used, such an amount is undesirable for economic reasons. Therefore, I prefer to use an amount which is just sutficient to form a saturated solution thereof with the oil at the treating temperature employed.

The treating time depends upon the amount of metal contaminants present in the oil, the intimacy of the contacting during the treatment and the temperature at which the treating operation is conducted. In order to keep the contacting time at a minimum, thorough commingling of the reactants is desirable. I have found that when treating a substantially paralfinic oil containing a relatively small amount of metal as, for example, 40 to 50 parts per million of etioporphyrin vanadium complex, a contact time of about one minute is ordinarily sutficient at 180 C. to eflect a substantial reduction of the porphyrin vanadium complex content. Where the oil to be demetalized is so viscous that intimate contacting with the aromatic sulfonic acid is difficult, it is advantageous to dilute the oil with a suitable hydrocarbon solvent. The solvent should not be volatile at the contacting temperature and pressure employed. The volatility of the solvent, however, should be such that it can be readily separated from the oil.

The process of the invention is illustrated by the following specific examples:

Example 1 Into a flask equipped with a stirrer was placed 150 milliliters of a 1:2 by volume white mineral oil: n-decane mixture containing 49 parts per million of etioporphyrin I vanadium complex. The solution was heated to about 180 C. in the presence of air. To this solution was added 0.2 gram of benzene sulfonic acid which corresponds to about 0.18 percent by weight based on the contaminated oil mixture. The reaction mass was then agitated for a period of about one minute at a temperature of about 180 C. Thereafter the mixture was cooled to room temperature and filtered through a fluted filter paper to remove the precipitated benzene sulfonic acidporphyrin vanadium complex. The filtrate was scanned on a spectrophotometer and the concentration of etioporphyrin I vanadium complex in the filtrate was found to be about 4.1 parts per million. The treatment with benzene sulfonic acid thus removed about 92 percent of the porphyrin vanadium complex from the oil.

Example 2 Into a flask equipped with a stirrer was placed 150 milliliters of a 1:2 by volume white mineral oil: n-decane mixture containing about 109 parts per million of etioporphyrin I vanadium complex. The solution was heated to approximately 180 C. under a blanket of nitrogen. To this solution was added 0.17 gram of benzene sulfonic acid which corresponds to about 0.15 percent by weight based on the contaminated oil mixture. The reaction mass was then agitated for a period of about one minute at a temperature of about 180 C. Thereafter the mixture was cooled to room temperature and filtered through a fluted filter paper to remove the precipitated benzene sulfonic acid-porphyrin vanadium complex. The filtrate was scanned on a spectrophotometer and the concentration of the etioporphyrin I vanadium complex in the filtrate was found to be 23 parts per million. The treatment with benzene sulfonic acid thus removed about 79 percent of the porphyrin vanadium complex from the oil.

Example 3 Into a flask equipped with a stirrer was placed milliliters of a 1:2 by volume white mineral oil: n-decane mixture containing 124 parts per million of etioporphyrin I vanadium complex. The solution was heated to about C. To this solution was added 0.19 gram of benzene sulfonic acid which corresponds to about 0.17 percent by weight based on the contaminated oil mixture. The reaction mass was then agitated While air was bubbled through the oil until the mixture was cooled to room temperature. It was filtered through a fluted filter paper to remove the precipitated benzene sulfonic acid-porphyrin vanadium complex. The filtrate was scanned on a spectrophotometer and the concentration of the etioporphyrin I vanadium complex in the filtrate was found to be about 23 parts per million. The treatment with benzene sulfonic acid thus removed about 81 percent of the porphyrin vanadium complex from the oil.

Example 4 In this example, a catalytic cracking charge stock of Mara crude oil was employed. Spectral examination of the crude oil showed it to contain 72.5 parts per million of porphyrin vanadium complexes. A solution was formed by adding sufficient spectrally pure n-decane to 5.2 grams of the crude oil to give a total of 25 ml. The solution thus formed was heated to about 156 C. To the heated solution was added 0.095 gram of benzene sulfonic acid which corresponds to about 0.27 percent by weight of the solution. The mixture was shaken vigorously for one minute and then cooled under tap water to room temperature in about two minutes. A benzene sulfonic acidporphyrin vanadium complex separated as a dark film on the walls of the treating vessel. The mixture was filtered through glass wool to remove the benzene sulfonic acid porphyrin vanadium complex which remained in suspension in the oil. Upon spectral examination of the filtered oil, it was found to contain only 26.3 parts per million of porphyrin vanadium complex. The treatment with benzene sulfonic acid thus removed about 64 percent of the porphyrin vanadium complex from the oil. In addition to removal of the porphyrin vanadium complex, examination of the oil showed substantial improvement in its color.

Example 5 Into a flask was placed 25 milliliters of a 1:2 by volume white mineral oil: n-dodecane mixture containing 101.6 parts per million of etioporphyrin I nickel complex. The solution was heated to about 180 C. To the heated solution was added 0.037 gram of benzene sulfonic acid corresponding to about 0.204 percent by weight based on the oil solution being treated. The mixture was then vigorously shaken for about one minute and then cooled under tap water to room temperature in about two minutes. The cooled mixture Was then centrifuged to remove the precipitated benzene sulfonic acid-porphyrin nickel complex. The centrifuged oil-dodecane mixture was then scanned on a spectrophotometer and the concentration of etioporphyrin I nickel complex in the mixture was found to be about 6.4 parts per million. The treatment with benzene sulfonic acid thus removed about 94 percent of the porphyrin nickel complex from the oil-dodecane mixture.

Example 6 Into a flask was placed 25 milliliters of a 1:2 by volume white material oil: n-dodecane mixture containing 101.6 parts per million of etioporphyrin I nickel complex. The solution was heated to about 215 C. To the heated solution was added 0.026 gram of p-t-oluene sulfonic acid corresponding to about 0.143 percent by weight based on the oil solution being treated. The mixture was then vigorously shaken for about one minute and then cooled under tap water to room temperature in about two minutes. The cooled mixture was then centrifuged to remove the precipitated p toluene sulfonic acid-porphyrin nickel complex, The centrifuged oil-dodecane mixture was then scanned on a spectrophotometer and the concentration of etiop orphyrin I nickel complex in the mixture was found to be about 34.6 parts per million. The treatment with p-toluene sulfonic acid thus removed about 65 percent of the porphyrin nickel complex from the oildodecane mixture.

Example 7 Into a flask was placed 25 milliliters of a 1:2 by volume white mineral oil: n-dodecane mixture containing 101.6 parts per million of etioporphyrin I nickel complex. The solution was heated to about 215 C. To the heated solution was added 0.026 gram of Z-naphthalene sulfonic acid corresponding to about 0.143 percent by weight based on the oil solution being treated. Themixture was then vigorously shaken for about one minute and then cooled under tap water to room temperature in about two minutes. The cooled mixture was then centrifuged to remove the precipitated Z-naphthalene sulfonic acidporphyrin nickel complex. The centrifuged oil-dodecane mixture was then scanned on a spectrophotometer and the concentration of etioporphyrin I nickel complex in the mixture was found to be about 54 parts per million. The treatment with Z-naphthalene sulfonic acid thus removed about 47 percent of the porphyrin nickel complex from the oil -dodecane mixture.

The above experiments clearly demonstrate the effectiveness of the process of my invention in reducing the porphyrin metallo complex content of mineral oils. Similar results are obtained when the benzene, p-toluene-, or naphthalene sulfonic acids are replaced by other aromatic sulfonic acids including xylene sulfonic acids, ethylbenzene sulfonic auid, mesitylene sulfonic acid, as well as the di-, triand tetrasulfonic acids of naphthalene.

In addition to obtaining an oil of reduced porphyrin metallo complex content by the process of the invention, there is also evidence that the general quality of the oil is improved as indicated by a decrease in the color.

While my invention has been described with reference to various specific examples and embodiments it will be understood that the invention is not limited to such examples and embodiments and may be variously practiced within the scope of the claims hereinafter made.

I claim:

1. A process for removing a heavy metal contaminant tacting the contaminated oil under anhydrous conditions in the liquid phase at a temperature of about 100 to about 250 C. with an aromatic sulfonic acid which is liquid at the treating temperature for a time and in an amount sulficient to form a complex between the aromatic sulfonic acid and said contaminant, cooling the reaction mass to effect precipitation of the aromatic sulfonic acid-heavy; metal complex and separating the precipitated complexi from the reaction mass to obtain a mineral oil of reduced heavy metal content.

2. A process for reducing the porphyrin metallo complex content of a petroleum distillate containing the same comprising contacting said distillate under anhydrous conditions in the liquid phase at a temperature of about 100 to about 250 C. with an aromatic sulfonic acid which is liquid at the treating temperature for a time and in an amount sufficient to form a saturated solution thereof with said distillate at the treating temperature employed, cooling the reaction mass to effect precipitation of an aromatic sulfonic acid-porphyrin metallo complex and separating the precipitated complex from the reaction mass to obtain a petroleum distillate of reduced porphyrin metallo complex content.

3. A process for reducing the porphyrin metallo complex content of a petroleum distillate containing the same comprising contacting said distillate under anhydrous conditions in the liquid phase at a temperature of about 100 to about 250 C. with about 0.05 to about 1 percent by weight of an aromatic sulfonic acid which is liquid at the treating temperature for a time sutficient to form a saturated solution thereof with said distillate at the treating temperature employed, cooling the reaction mass to eilect precipitation of an aromatic sulfonic acid-porphyrin metallo complex and separating the precipitated complex from the reaction mass to obtain a petroleum distillate of reduced porphyrin metallo complex content.

4. A process for reducing the porphyrin metallo complex content of a petroleum distillate containing the same comprising contacting said distillate under anhydrous conditions in the liquid phase at a temperature of about 100 to about 250 C. with about 0.05 to about 1 percent by weight of benzene sulfonic acid for a time sufficient to from a mineral oil containing the same comprising con- I form a saturated solution thereof with said distillate at the treating temperature employed, cooling the reaction mass to effect precipitation of a benzene sulfonic acidporphyrin metallo complex and separating the precipitated complex from the reaction mass to obtain a petroleum distillate of reduced porphyrin metallo complex content.

5. The process of claim 4 wherein the metal of said porphyrin metallo complex is selected from the group consisting of vanadium and nickel.

References Cited in the file of this patent UNITED STATES PATENTS 2,948,675 Case et al Aug. 9, 1959

Claims (1)

1. A PROCESS FOR REMOVING A HEAVY METAL CONTAMINANT FROM A MINERAL OIL CONTAINING THE SAME COMPRISING CONTACTING THE CONTAMINATED OIL UNDER ANHYDROUS CONDITIONS IN THE LIQUID PHASE AT A TEMPERATURE OF ABOUT 100* TO ABOUT 250*C. WITH AN AROMATIC SULFONIC ACID WHICH IS LIQUID AT THE TREATING TEMPERATURE FOR A TIME AND IN AN AMOUNT SUFFICIENT TO FORM A COMPLEX BETWEEN THE AROMATIC SULFONIC ACID AND SAID CONTAMINANT, COOLING THE REACTION MASS TO EFFECT PRECIPITATION OF THE AROMATIC SULFONIC ACID-HEAVY METAL COMPLEX AND SEPARATING THE PRECIPITATED COMPLEX FROM THE REACTION MASS TO OBTAIN A MINERAL OIL OF REDUCED HEAVY METAL CONTENT.