US2450588A - Desulfurization of oils - Google Patents

Description

Oct. 5, 1948. B. L. EVERING ETAL DESULFURIZATION OF OILS 2 Sheng-sheet 1 Filed May 19, 1945 Det. 5, 1948.

Filed May 19, 1945 FLSH DRUM EXTRA C TOR 2 Sheets-Sheet 2 EXTRA CTOR Feed In v`enors. Bernard L. Ever-ing #rf/zur Lien James IVI. Page, Jr

Patented Oct. 5, 1948 UNITED STATES; PATENT .OFFICE DE SULFURIZATION OF OILS Bernard L. Evering', Chicago, Ill., Arthur P. Lien,

Hammond, Ind., and James M. Page, Jr., Chicago, Ill., assignors to Standard Oil Company, Chicago, Ill., a corporation of Indiana Application May 19, 1945, serial No. 594,610

The present invention pertains to improvements in the refining of non-viscous hydrocarbon 4 Claims. (Cl. 196-31) oils and more particularly pertains to the desulextraction of petroleum oils with a mixture 'of anhydrous liquid HF and BFa possesses the undesirable feature in that any aromatics present in the stock extracted are also removed as part of the extract. The removal of aromatics from various petroleum fractions may not be undesirable. but for the treatment of certain fractions, particularly the lighter fractions boiling within the naphtha distillation. range and up to a maxlmum distillation temperature at about atmospliericl pressure of about 450 F., it is highly desirable to retain in such fractions any aromatics which may be contained therein.

It is an object of the present invention to provide a solvent extraction method of desulfurizing non-viscous petroleum fractions without the re-l moval of substantial quantities of aromatics. An-

, about 50 volume percent, although for certain other object of the inventionis to provide an improved process of solvent extracting non-viscous petroleum fractions with a solvent which is selective to the removal of sulfur from such. fractions. Another object of the invention is to provide an improved solvent extraction process forthe removal of sulfur and sulfur-containing'constituents from petroleum-naphtha boiling within the motor fuel distillation range. Another object of the invention is to provide an improved method for the desulfurization of petroleum naphthas. Still another object of the invention is to provide an improved process for the removal of sulfur withoutthe removal of substantial quantities of aromatics from petroleum naphthas. Other objects and advantages of the present invention will become apparent from the following description thereof read in conjunction with the accompanying drawing in which Figure 1 is a flow `diagram of a preferred method of carrying out the present invention, and Figure 2 is a, ow diagram of a modiedmethod of treating the initial feed stock.

In accordance with the present invention the 'foregoing objects can be attained non-viscous petroleum oil fractions, such as naphthas and motor fuels, with a solvent consisting of anhydrous liquid hydrogen fluoride. The quantity of anhydrous liquid hydrogen fluoride employed should be sufficient to give a diphasic separation, and can vary from about 10 volume percent to about 100 volume percent or more and preferably from about 15 volume percent to types' of oils as little as 5 volume percent or less will givek a diphasic separation. Temperatures of from about 0 F. to about 212.J F. and preferably from about 32 F. to about 100 can be employed. However, if desired somewhat higher temperature, for example temperatures of about 400 F. can be used, in the manner hereinafter described. A pressure suiiicient to maintain the solvent in the liquid phase is preferably maintained in the extraction chamber. A contact time of from about one minute to about 120 min-` utes or more can be employed, although a contactY time of from about 5 minutes to about 60 minutes is usually suflicent.

A method for practising the present invention is illustrated by the following example:

Referring to Figure 1, va sulfur-containing gasoline fraction having an initial boiling point of about 215 F. and an end point of about 420 F. by A. S. T. M. distillation, is introduced through ,line I0 into the bottom portion of the extractor l II, while liquid anhydrous hydrogen fluoride is introduced into the upper portion of the extractorV through a line I2. The extractor II is suitably a 'packed column in which anhydrous hydrogen fluoride and the sulfur-containing feed stock are contacted countercurrently, although other suitable means of obtaining intimate contact can be employed. The extractor II is operated at 'a temperature within the range of fromabout 0 F. to about 212 F. and preferably from about 32F.- to about 100 F., and under sufficient pressure to maintain the reactants in the .liquid phase. l l

A raffinate substantially free of sulfur or having a sulfur-content substantially lower than that ,of` the feed stock, vis removed from the extractor II through a line I3 and introduced into a settler I4,Wherein any entrained HF or HF extract is settled out and returned through a line I5 to the extractor I I via line 58. The raillnate containing dissolved hydrogen fluoride inthe settler I4 is by extractin'g n upon the stock being treated.

introduced through aline I6 and e. pump IBa into the bottom portion of a stripper I1. Even when the overhead from the extractor II does not contain entrained HF, it is advantageous to employ settler I4 to function as an accumulator and to protect against surges. Gases in settler I4 can be vented through a vent (not shown) or withdrawn through lines I8, I9 and I2, and returned to the extractor II. If desired, the overhead from the extractor II can be passed through lines I3 and I3a to the stripper I1, thereby by-passing settler I4,

The ramnate product stream introduced into the stripper I1 is heated by suitable means, such as by a heating coil 20, to remove hydrogen fluoride from the product. Stripper I1 is operated under pressure and temperature conditions to assure the removal of substantially all of the hydrogen fluoride from the rafilnate product. These conditions-will vary over a wide range depending For example. when a gasoline fraction having the aforementioned distillation characteristics is employed as the feed stock, temperatures within the range of from about 200 F. to about 450 F., and preferably from about 300 F. to about 400 F. and pressures from about'5 to about 150 pounds per square inch, and preferably from about 25 to about 100 pounds per square inch are suitably employed. Hydrogen fluoride separated in the stripper I1 is removed overhead through a line 2I and can be directed through line 22 to the hydrogen fluoride storage tank 23; or can be recycled through lines 24, 25, I9 and I2 to the extractor Il. hydrogen fluoride can be introduced into the system through line 23a.

The bottoms from the stripper I1 comprising a substantially desulfurized ralnate product substantially free of hydrogen fluoride can normally be removed from the stripper I1 through alline 26 and passed through a conventional bauxite tower 21, or other suitable system to insure the removal of iluorides, such as hydrogen fluoride and alkyl fiuorides which may be contained in the desulfurized product from the stripper I1. The desulfurized product, substantially free of iluorides, is removed from the tower 21 through a line 28.

When a stock, such as furized contains butanes, an azeotrope with the hydrogen fluoride may be formed. To separate the components of the azeotrope the butane-hydrogen fluoride from stripper I'I through lines 2l, 22, valved line 29 and a condenser 30 to a settler 3l which is operated at as low a temperature as can beobtained with available cooling water, preferably at a. temperature well below 100 F. The condensed azeotrope separates into a heavier hydrogen fluoride layer which is withdrawn through lines '32 and 22 to the hydrogen fluoride storage tank 23. u The upper butane` layer is returned through pump 33 and line 34 as reflux to the top of stripper I 1. Lighter gases and some propane nay be vented from the settler 3l through a line 3 gasoline, being desul- The hydrogen fluoride extract from the extractor I I is passed through a line v36 to a hydrogen fluoride recovery tower 31, the bottom temperature of which is maintained at a temperature between about 100 F. to 150 F. by heating coil 38, to drive off the unbound hydrogen fluoride, The hydrogen fluoride from the tower- 31 is passed through lines 39 and 4II through a condenser 4I to a receiver 42. If the extract from Makeup I azeotrope is passed overhead pounds along with the extractor II contains some low boiling hydrocarbon fractions, the overhead from the tower 3l is first fractionated by suitable means (not shown) to fractionate the hydrogen fluoride from the low boiling hydrocarbons before the former is recycled to the hydrogen fluoride storage tank 23. The bottom from the tower 31 is passed through a line 43 to a second hydrogen fluoride recovery tower 44, provided with suitable heating means,l such as a heating coil 45 to maintain a bottom temperature therein of from about F. to about 500 F. to decompose the chemically bound hydrogen fluoride which is passed from tower 44 through lines 46, 40 and condenser 4I to the receiver 42, while the extract, substantially free of hydrogen fluoride, but having a high sulfur content is removed from the tower 44 through a line 41.

Some'water enters the system through the feed stock and makeup hydrogen fluoride. To prevent this water from building up in the system, it is removed by by-passing a portion of the recycled hydrogen fluoride from towers 31 and 44 through a line 48 to a hydrogen fluoride-water azeotrope silver-lined distillation tower 49, provided with a suitable heating means 50 in the bottom portion thereof. Anhydrous hydrogen fluoride is removed overhead from the tower 49, through lines 5I and 40 and condenser 4I to receiver 42, and aqueous hydrogen fluoride is removed from the bottom of tower 49 through a line 52. A portion of the anhydrous hydrogen fluoride in receiver 42 is returned through line 53 and pump 54 to the top of tower 49 to serve as reflux. The hy.. drogen fluoride in receiver 42 can be passed via pump 55 and a line 56 to the storage tank 23.

A portion of the extract from extractor II may, if desired, be recycled to the extractor I I through lines 51 and 58. Itis to be understood that while we have shown a single extractor in Figure 1, a plurality of extractors may be used; also HF extract can be recycled to the same extractor or to diuerent extractors.

In the foregoing example we have described extraction at a temperature up to about 212 F. Under some conditions it may be desirable to carry out a conversion and/or an extraction at an elevated temperature above about 212 F., for example about 300 F. to 400 F., followed by an extraction at a lower temperature, for example, about 0 F. to about 212 F., preferably about 75 F. Thus, the sulfur-containing feed stock can be contacted with liquid anhydrous hydrogen uoride at the elevated temperature, say about'400 F. and the hydrogen sulfide, resulting from the conversion of some of the sulfur comany lighter hydrocarbons, after cooling, is flashedoff. The resultant mixture of hydrogen fluoride and treated product can then be cooled to the final extracting temperature, for example about '75 F., additional hydrogen iluoride added if necessary and the extraction process proceeding as above described. If desired, a, diphasic separation can be made after contacting at the elevated temperature and cooling to the lower temperature, the extract layer removed, additional hydrogen fluoride added and an extraction made at a temperature of from about 0 F. to about 212 F., preferably about 75 F. as above described. This combined conversionextraction process results in a very effective desulfurlzation of the stock so treated.

This modied high temperature treatment of the initial feed stock can be carried out as follows: Referring to Figure 2 the feed stock, containing sulfur, and hydrogen fluoride are introduced into the extractor II through lines I and I2 respectively, and the mixture hea-ted to a temperature above about 212 F., for example from about 300 F. to 400 F. The heated mixture from the extractor II is passed through line I3 anda cooler I3b to a flash drum Ilia wherein hydrogen sulfide resulting from the conversion of the sulfur compounds in the feed stock, along with light hydrocarbon, are hushed ofi through vent IIb. The mixture of hydrogen fluoride and treated product in flash drum Ida is passed through line I5a and cooler I5b to extractor IIa and mixed with additional hydrogen fluoride introduced through line |2a. A pressure sufficient to keep the hydrogen fluoride and hydrocarbon oil in theliquid phase is maintained within the extractor I Ia. The mixture of hydrogen uoride and oil in extractor I Ia is allowed to separate into a'. raffinate phase and an extract phase, and the raffinate withdrawn from the extractor IIa through line IIb passed to settler I4 (Figure 1) and thereafter processed as hereinbefore described in connection with Figure 1. The extract is withdrawn from the extractor IIa through line 36a and introduced via line 36 to the hydrogen fluoride recovery tower No. I (shown in Figure l) and thereafter processed as hereinbefore described.

Alternatively, themixture of oil and hydrogen fluoride in extractor I Ia may be agitated without added hydrogen fluoride and then separated into a railinate phase and extract phase. The rafll-A.

nate phase may then be withdrawn through line IIa and the extract phase through line 36a and .processed as above described. If desired, the extract in the extractor IIb may be withdrawn through line 36a, additional hydrogen fluoride introduced into the extractor IIa through line I2a, the mixture agitated and -then settled to obtain a further rainate phase and extract phase which may then be withdrawn from extractor I Ia and processed in themanner hereinbefore described.l

The ellectiveness of anhydrous liquid hydrogen fluoride as a solvent extractant for the removal of sulfur from non-viscous hydrocarbon oils is demonstrated by the data in Table I. These data Were obtained by extracting a heavy naphtha cut hydrogen fluoride and boron fluoride is clearly obtained by extracting at a temperature cf about 80 F. and with acontact time of about 60 minutes a heavy'naphtha having initial distilla tion of about 218 F. and an end point of about 416 F. from Slaughter crude, using as the solvent extractant anhydrous liquid hydrogen fluoride alone, and anhydrous liquid hydrogen fluoride in combinationv 'with boron fluoride. Run 1 was made by extracting the heavylnaphtha with a mixture of 400 cc. of hydrogen fluoride per liter of naphtha and" 67 grams of boron fluoride per liter of naphtha which vgave an initial boron iluoride pressure of pounds per square inch in the extractor. Run 2 was made underidentical conditions as in Run 1 except that the boron fluoride was omitted.

`TABLE II s Di Octane No. T v pcc. sp. HIL

Bu ko' HF BF Rallinatc Loss Wt.

Clear 3 cc. Percent ne l41.9 54.2 f 104 35. 6 604 7 15.1 116 40. 3 G1. 5 2. 3

Comparison of the specific dispersions of the feed stock and the raiiinate from Runs 1 and 2 show that with the hydrogen fluoride alone the extraction of aromatics is substantially negligible, whereas with the mixture of hydro-gen fluoride and boron fluoride a high degree of aromatic extraction .took place The specific dispersion value indicates the degree of aromatlcity of the extracted naphtha. The specific dispersion value of 116 inthe feed'and in Run 2 indicates substantially no removal of aromatics from the feed stock, whereas the specific dispersion value of 104 for the raffinate in Run 1 indicates-a substantial degree of -aromatic extraction from the having a boiling range of from 218 F. to 416 F.

lfrom a high sulfur crude oil with varyingvquantitles of anhydrous liquid HF at a temperature of about 80 F.

feed stock. The method of determining the specie dispersion is described in the article Quantitative Determination of Aromatic Hydrocarbons by a New Method by A. V. Grosse and R. C. Wackher, published in the Industrial and Engineering Chemistry Analytical Edition, volume 11, No. 11 (November 15, 1939) pages 614 to 624 inclusive. As shownlby the date in Table II, the effect of aromatic removal is reflected in the high TABLE I Sulfur extraction of heavy naphtha 'Dooren Extract Treating Octane No. CFR-M Run ce HF l of Sulfury Loyer Loss, I No. 28g what liixr...vt.| wt. per. Wt.

i r pci-crut l wuts pcrccntl Clear lcc. 3cc. l l ma! o ss! a 41.9 48.9 54.2 I 5 i i) 0S l 79.0 17.3 1.74 41.0 50.0 57.4 wn e on als mi 1.89 40.7 50.9 59.6 1:. '20o o 03 v2.0 l 15.2 2.18 40.7 52.1 62.1

l Based on S Analyses.

The above data show a substantially complete rel moval of sulfur from heavy naphtha. Although the raflinate show a slightly lower elearoctane rating than the feed, better lead responses are obtained on the desulfurized stocks. The low treat.-

ing losses reflect a substantially negligible extraction of aromatics from the feed stock, l

The advantage of extracting non-viscous hydrocarbon oils of the type herein-described with hydrogen fluoride alone over using a. mixture of greater removal of aromatics is also reflected in the antiknock rating of the motor fuel. It will be noted that in Run 1 there was obtained a lowering of the clear octane number of from 41.9 for the feed stockto 35.6. whereas when hydrogen ing the dashed lower for the railinate obtained in the 4hydrogen nuoride and boron iluoride treatment than for the raillnate obtained in th'e; extraction using hydrogen nuoride alone.

The present invention is not to be confused with prior art processes ot. treating petroleum stocks with liquid hydrogenA fluoride. wherein the hydrogen fluoride is employed as a treating agent in amounts and under conditions lwhich do not permit stratiilcation into a railinate fraction and an extract fraction. The process of the hereindescribed invention in contradistinction to' prior art processes provides a process whereby the suliur-containing constituents `of the non-viscous hydrocarbon oils are extracted with a suincient quantity of anhydrous liquid hydrogen fluoride to permit stratication of a substantially sulfuri'ree raiiinate and a sulfur-containing extract, the solvent in both the ranlnate and the extract being recovered and recycled for further extraction of the feed stock.

In addition to the removal of sulfur4 from nonviscous hydrocarbon oils, extraction with' liquid anhydrous hydrogen uoride also effectively removes nitrogen and/or oxygen compounds from such stocks.

The term non-viscous hydrocarbon oil" as used herein and in the appended claims means a hydrocarbon oil less viscous `than hydrocarbon oils within the lubricating oil range; namely,

those having a Saybolt Universal viscosity at 100 F. of less than about 60 seconds.

It is to be understood that while certain preferred embodiments of the invention have been herein-described. the invention; is not to be limited thereto, but includes within its scope such modifications as fairly come within the spirit of the appended claims.

Weclaim: i

1. The method of selectively desulfurizing a non-viscous aromatic-containing hydrocarbon oil comprising contacting said oil with a solvent consisting of liquid anhydrous hydrogen fluoride at a temperature within the range of about 300 F. to about 400 F., iiashing olT any hydrocarbon gases and hydrogen sulfide resulting from the conversion of sulfur compounds in said oil, coolmixture of hydrocarbons and hydrogen iluoride to a temperature of from about F. to about 212 F., contacting the cooled mixture with additional liquid anhydrous hydrogen nuoride while maintaining a pressure suilicient to maintain the solvent and hydrocarbon oil in the liquid phase, permitting the mixture of said oil and liquid hydrogen fluoride to stratify into an aromatic-containing ratllnate phase substantially free of sulfur and a sulfur-containing extract phase, separating said phases and removing the hydrogen nuoride from said phases.

2. The method of selectively desulfurizing a non-viscous aromatic-containinghydrocarbon oil comprising treating said oil with liquid anhydrous hydrogen fluoride at a temperature with- 8 in the range of about 300 flashing of! any hydrocarbon sulnde resulting from the conversion of sulfur compounds in said oil, cooling the ashed mixture to a temperature of from about 0 F. to about 212 F.. agitating said mixture at said lower temseparate into an aromatic-containing railinate phase substantially free of sulfur and a sulfurcontaining extract phase and separating said phases.

3. I'he method of non-viscous aromatic-containing hydrocarbon oii fur compounds in said oil, cooling the flashed mixture to a temperature of about 0 F. to about 212 F., permitting .the mixture to separate into to about 400 F., cooling the mixture to a tem-v perature of from about 0 F. .to about 212 F.. contacting the cooled mixture with additional liquid anhydrous hydrogen fluoride while maintaining a pressure sunlcient to maintain the solvent and hydrocarbon oil in the liquid phase, permitting the mixture of said oil and liquid hydrogen fluoride to stratify into an aromatic-containing raiiinate phase substantially free of silliur and a sulfur-containing phase, separating said phases and removing the hydrogen nuoride from said phases.

BERNARD L. EVERING. ARTHUR P. LIEN. JAMES M. PAGE, Jn. REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS 60 Number Name Date 2,282,451 Brooks May 12, 1942 2,320,629 Matuszak June 1, 1943 2,343,841 Burk Mar. 7, 1944 2,366,743 Matuszak Jan. 9. 1945 65 2,371,341 Matuszak Mar. 13, 1945 2,375,675 Matuszak May 8, 1945 2,378,762 Frey June 19, 1945

Images