US2767120A - Process for refining hydrocarbons with boron trifluoride followed by a solvent - Google Patents

Description

. A. P. STUART PROCESS FOR REFINING HYDROCARBGNS WITH BQRON Oct. 16., 1956 TRIFLUORIDE FOLLOWED 'BY A SOLVENT Filed June 30, 1955 JBMOl bugqso JSMOl uogoouxg Jexgw T T Y m k V my sm P. T D m A L A L B m R q A 4 AIIK um 2 220 55:00:25

United States Patent Archibald P. Stuart, Media, Pa., assignor to Sun Oil Company, Philadelphia, Pa., a corporation of New Jersey Application June 30, 1955, Serial No. 519,116

7 Claims. (CL 196-24) This invention relates to a process for refining hydrocarbon materials containing one or more undesirable impurities. More particularly, the invention relates to a process for removing non-hydrocarbons, such as sulfur compounds, from admixtures thereof with hydrocarbons, such as petroleum oil fractions containing sulfur compounds.

Various processes for removing non-hydrocarbons from hydrocarbon materials have heretofore been described. It is known, for example, to treat hydrocarbon oils with Bib, either alone or as a complex with another material such as an oxygenated organic compound. After the BE; treatment such processes generally require a neutralization step, which is accomplished by washing the treated hydrocarbon material with an aqueous caustic solution or by treating with ammonia gas. Such processes, however, while effective for removing a portion of the nonhydrocarbons have generally been unsatisfactory in that a refined product that is stable to oxidation is not obtained.

it has now been found that a refined, stable hydrocarbon product can be obtained from a mixture of a hydrocarbon material with one or more non-hydrocarbon materials by treating the mixture with BFs so that a sludge is formed, separating the sludge from the system, and extracting the separated hydrocarbon material with a solvent for the reaction product of BF and non-hydrocarbons.

The accompanying figure is a flow diagram illustrating an embodiment of the process of the invention and is more fully described hereinafter.

In accordance with the invention, a hydrocarbon material mixed with one or more non-hydrocarbon materials is treated with ER. This treatment converts a large proportion of the non-hydrocarbons to materials insoluble in the hydrocarbon material. The so-formed sludge is separated from the body of the hydrocarbon material. The hydrocarbon material is then extracted by contacting with a solvent for the reaction product of BFs and the non-hydrocarbons. The extracted hydrocarbon material is then preferably washed with water and dried. It has been found that the product of this process is highly refined and stable against oxidation.

While it is not known with certainty why the process of the invention is remarkably efiEecti-ve in producing a highly refined, stable hydrocarbon product, it is believed that, while a. large proportion of the reaction products of BF?, and the non-hydrocarbons is insoluble in the hydrocarbon material, at least a portion of such reaction products is soluble in the hydrocarbon material. soluble reaction products are not separable as sludge and, with heretofore used processes, appear to remain as impurities in the hydrocarbon material. In the process of the present invention, these soluble reaction products are removed from the hydrocarbon material by extraction with a solvent for such reaction materials. In this manner, a hydrocarbon product more highly refined and sta- Such r 2,767,120 Patented Oct. 16, 1956 ble than products of heretofore known processes is obtained.

Hydrocarbon materials containing non-hydrocarbon impurities which can be employed in the process of the invention are the petroleum hydrocarbon fractions such as gasoline, naphtha, kerosene, fuel oil, gas oil and lubricating oil fractions Which contain minor quantities of non-hydrocarbons such as sulfur, oxygen or nitrogen compounds, or mixtures thereof. The quantity of non-hydro: carbons present in such fractions will generally be from about .05 to 8% and usually from .1 to 2%. Such petroleum hydrocarbon oils may have been subjected to var-i ous treatments prior to their use in the process of the invention. For example, oils which have been subjected to solvent extraction, acid treatment, clay contacting, and the like, can advantageously be employed.

The quantity of BF3 to employ is advantageously varied in accordance with the quantity of non-hydrocarbons present in the hydrocarbon material being treated. While an excess is not deleterious, the quantity of BFa should be maintained Within the range of from 0.01 to 10% by weight of the oil, and usually will be within the range of from 0.05 to 5% by weight :of the oil. The time, temperature and pressure to employ during the BFs contacting do not appear critical. Usually a time of from '5 to 60 minutes will be employed because of practical considerations. The pressure can be sub-atmospheric, atiITlOSPhBIlC or super-atmospheric, but is advantageously from atmospheric to 200 p. s. i. g. Preferably ambient temperature is used, but a relatively low temperature, say about 30 F, or a relatively high temperature, say about 300 F., can be advantageously used in some instances... An elevated temperature is advantageously used, for example, to lower the viscosity :of a heavy oil for the BF:.

treatment.

The solvent to employ in the process should be etfeo. tive for dissolving the reaction product of BFs and the; non-hydrocarbon or non-hydrocarbons present in the hy-' drocarbon materials, and should be substantially immiscible with the hydrocarbon material. Acetic acid is the preferred solvent, but other relatively low molecular: weight acids having not more than 4 carbon atoms, such as formic acid, propionic acid and butyric acid, can be used. Other solvents can be substituted in whole or in part for the described acids such as the niu'iles of the described acids, esters having not more than a total of 8 carbon atoms such as methyl acetate, ethyl acetate, methyl propionate and ethyl propionate, alcohols having a total of not more than 6 carbon atoms such as methanol, ethanol, butanol and hexanol, and amides having a total of not more than 6 carbon atoms, preferably di methyl formamide. The quantity of solvent employed should be at least suflicient to form a-separate phase when admixed with a hydrocarbon material. A quantity of from 0.5 to 10 volumes of solvent or more per volume of hydrocarbon materials gives good results, but it is preferred to employ at least 2 volumes of solvent per volume of hydrocarbon material. I

The solvent extraction can be performed by conventional means, such as continuously by use of an extraction tower, or batchwise by intimately contacting the solvent and hydrocarbon material, allowing two phases to separate, and separating the phases by decanting. While it is generally unnecessary, it is advantageous in some instances, after the solvent extraction step, to wash' the hydrocarbon materials with water and follow the washing step with a drying step. The Washing step is: conveniently accomplished by intimately contacting water with the hydrocarbon materials continuously in an extraction tower, or batchwise by mechanical mixing, lowing the water to form a separate phase, and decanting. The drying step is conveniently accomplished by passing an inert gas such 'as flue gas or nitrogen through the washed hydrocarbon materials, preferably at an elevated temperature, but other drying means known to the art can be employed if desired. J Attention is now directed to the accompanying figure which is a flow diagram illustrating anembodirnent of the process of the invention. The hydrocarbon charge inaterial is introduced into the process through line 1 and passes into mixer 2, wherein the hydrocarbon charge is admixed with BFs introduced through line 4. The resulting admixture is passed through line '5 to settler 6, wherein sludge formed by the action of BB upon the non-hydrocarbon constituents of the hydrocarbon charge settles out and is removed from the proces through line 8.; Line 9 and valve 10 are provided to release excess BFs, if any, from the reaction'mixture, and to provide for pressure control if desired. From-settler 6 the hydrocarbon material is passed through line 11 into extraction tower 12, wherein it is contacted with acetic acid introduced through line 14. The hydrocarbon material leaves extraction tower 12 through line 15 and is passed to washing tower 16. Acetic acid is removed from extraction tower 12 through line 18 and is passed to a purification step 19 wherein materials extracted by the acetic acid are removed through line 20. Acetic acid is recycled through the system through lines 21 and 14. The

purification of acetic acid as shown by 19 is conveniently accomplished by distillation, but other means can be employed if desired. carbons are contacted with water introduced through line '22. The water, containing any residual acetic acid from the extraction tower, leaves Washing tower 16 through line 24. The washed hydrocarbons are passed through line 25 to drier 26 wherein moisture is removed. This can be accomplished by heating and/or by passing an inert gas through the hydrocarbon material, or by other means if desired.- The refined hydrocarbon product of the process is removed from drier 26 through line 28. In the flow diagram, as above described, valves, pumps,

meters, and the like, the location and operation of which will be apparent to those skilled in the art, have been largely omitted.

Other embodiments of the process can be employed if desired. For example, it is unnecessary to completely separate sludge formed with the BF; prior to the solvent.

extraction step, i. e., at least a portion of the sludge can remain with the hydrocarbon charge to the extraction step. It is necessary, however, in accordance with the invention, to treat with BF3 to form a sludge prior to contacting the hydrocarbon material with the solvent.

The following examples illustrate the process of the invention, in which parts refers to parts by weight:

s 788.3 parts of a solvent refined lubricating oil was treated with 11.3 parts of. BFs. The lubricating oil charge had a boiling range of from 536 F. to 745 F., a viscosity of about 57 SUS at 100 F. and about 33.9 SUS at 210 F., and contained about 0.14% by weight sulfur compounds (calculated as sulfur), about 0.004% by weight nitrogen compounds (calculated as nitrogen), and about 0.097% by weight oxygen compounds (calculated as oxygen). The BF3 treatment was performed by introducing the BFs into the oil contained in a pressure vessel. The pressure, due to the addition of BF3,

In washing tower 16, the hydro-' was yellow, from the third extraction was slightly yellow, and from the remaining extractions was clear. The oil product, designated as B, had an oxygen content of below 0.01% by weight (calculated as oxygen) and a sulfur content of about 0.08% by weight (calculated as sulfur), and was testedasdescribed below.

0.02% by weight dibutyl-p-cresol, a known oxidation inhibitonwas added 'to both A' and B and the inhibited.

products subjected'tooxidation... Interfacial tension between water and oil was used to measure the extent of oxidation of the oil (ASTM methodD971-50). The

oxidation procedure was to pass air for 96 hoursat a) rate of 7 ml. of air (measured at ambient temperature.

and pressure) per ml. .of oil per minute through a 7O varied from about 165 to 150 p. s. i. g. Ambient temperature, about 70 F., was used. After contacting the oil and BF3 for about 15 .minutes, the excess BFa was released and 'the sludge formed was separated by cen- The resulting BFs treated oil was divided into two parts, hereinafter designated Part A and fPart B.

The acidity of part A was neutralized with ammonia.

.partsof glacial acetic acid. The acid from the first extraction was dark brown, from the second extraction ml. oil sample maintained at 200 F. in contact with 25 cm. of iron wire (B. & S. No. 19) and 25 cm. of copper Wire (B. & S. No. 18). Prior to oxidation both A and B exhibited an interfacial tension of about 42.

Results obtained were as follows:

Product Interracial tension to the BFs treatment, designated as Part C and fPart' Part C was treated with BFs and subsequently extracted with a glacial acetic acid, in accordance with the process of the invention as above described; the product is designated below as C.

Part D extracted with glacial acetic acid seven times using the quantities and procedure as above described, the product is designated below as D, and was the hydrocarbon charge material not treated with BFa, but which was extracted with glacial acetic acid.

Both C and D, to which were added 0.02% by weight dibutyl-p-cresol, were tested by ASTM method D943-54 modified by humidifying the oxygen by passage through water (instead of using drying oxygen) prior to its introduction into the test system, by adding 6 cc. (instead of 60 cc.) of water to the oil, and by introducing the oxygen into the oil layer (instead of the water layer). Results show the life of the oils to be as follows:

Product Life (hours) When other hydrocarbon materials containing nonhydrocarbons, and when other solvents for the reaction products of BFs and non-hydrocarbons are employed, as above described, results substantially equivalent to those above described are obtained.

The invention claimed is:

1. Process for desulfurizing a petroleum hydrocarbon fraction which comprises contacting a petroleum hydrocarbon fraction containing sulfur compounds with BFs to form a sludge, separating said sludge from the hydrocarbon fraction, extracting the separated hydrocarbon fraction with a solventselected from the group consisting of organic acids having not more than 4 carbon atoms, the nitriles of said-acids, esters having a total of not more than 8 carbon atoms, alcohols having a total of not more than 6 carbon atoms, and amides having a total V of not more than 6 carbon atoms.

2. Process for desulfurizing a petroleum hydrocarbon oil which comprises contacting said oil with from 0.01 to 10% by weight BFa to form a sludge, separating the sludge from the reaction mixture, extracting the resulting reaction mixture with a solvent selected from the group consisting of organic acids having not more than 4 carbon atoms, the nitriles of said acids, esters having a total of not more than 8 carbon atoms, alcohols having a total of not more than 6 carbon atoms, and amides having a total of not more than 6 carbon atoms, washing the extracted oil with Water and drying the washed oil.

3. Process according to claim 2 wherein said solvent is acetic acid.

4. Process according to claim 2 wherein said solvent is dimethyl formamide.

5. Process according to claim 2 wherein said solvent is propionic acid.

6. Process according to claim 2 wherein said solvent is butyric acid.

7. Process according to claim 2 wherein said solvent is methyl acetate.

References Cited in the file of this patent UNITED STATES PATENTS 2,343,841 Burk Mar. 7, 1944

Claims (1)

1. A PROCESS FOR DESULFURIZING A PETROLEUM HYDROCARBON FRACTION WHICH COMPRISES CONTACTING A PETROLEUM HYDROCARBON FRACTION CONTAINING SULFUR COMPOUNDS WITH BF3 TO FORM A SLUDGE, SEPARATING SAID SLUDGE FROM THE HYDROCARBON FRACTION, EXTRACTING THE SEPARATED HYDROCARBON FRACTION WITH A SOLVENT SELECTED FROM THE GROUP CONSISTING OF ORGANIC ACIDS HAVING NOT MORE THAN 4 CARBON ATOMS, THE NITRILES OF SAID ACIDS, ESTERS HAVING A TOTAL OF NOT MORE THAN 8 CARBON ATOMS, ALCOHOLS HAVING A TOTAL OF NOT MORE THAN 6 CARBON ATOMS, AND AMIDES HAVING A TOTAL OF NOT MORE THAN 6 CARBON ATOMS.

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