US3100744A - Maintaining the viscosity of solutizer salt solutions - Google Patents

Description

Allg- 1963 s. c; PHENIX, JR, ETAL 3,100,744

MAINTAINING THE VISCOSITY OFSOLUTIZER SALT SOLUTIONS Filed June 2, 1961 5 SheetsSheet 1 Effect of Xylenols Concentration onViscosity of KOR S m C m m8 w nC 0A GM /AT 1 e s O B /Q l we fi MB M m N mm Wm B m% m% P) BO dm 5 mf ue mm 00 C F O o o o o 0 w m 0 O O O O 7 6 5 4 3 2 1 20 30 1) O Xylenols Content in Organic Acids, wt.%

2) A Xylenols Contentin Total Acid Phase //7 venfors Dorr/ss Merchant Owen f? Mi/c/vel/ Bruce C Phen/x, Jz

SUS@IOOF g- 1963 B. c. PHENIX, JR., ETAL 3,100,744

MAINTAINING THE VISCOSITY OF SOLUTIZER SALT SOLUTIONS Filed June 2, 1961 3 Sheetssheet 2 IOO of Modifier (E BP-400F Cresylotes) has viscosiiy at 202 SUS 0 IO 4O I Weight Modifying Acidic Organic Material (Salt Solution) in Highviscosity Cresylote Treating Ag em 7 7f0 5 Dorr/ss H. Merchant Owen E. M/lche/l Bruce CP/Yen/X i/r,

1963 B. c. PHENlX, JR., ETAL 3,100,744

MAINTAINING THE VISCOSITY OF SOLUTIZER SALT SOLUTIONS Filed June 2, 1961 5 Sheets-Sheet 3 Effect of Different ModifyingAgenls on theViscosiiy and Xylenols Content of Aged Cresylole Treating Solution R" 600 e, 500 Mc difying Agent Symbol l O Cresylofe from E Q 9 Preferred Viscosity 2 Cresols ESP-400 F 400 ui Cresolyfe from I 5 Cresols EBP- 403F 3 Phenol O E 300 E fi/ I 7 .2 Z 200 g Preferred 3 Xylenol 5 Concentration Range (7 -l5) oo Chorfed Viscosity Equivalent /To Phenol Modifyerin Acid Phose 6, l l

O IO I5 Xylenols (wl.%) in Cresylole Phase in Equilibrium 'lh BE KOH lnven/ors Dar/1'55 H Mere/m Owen R Mllche/l Bruce GP/ven/x, i/n

3,100,744 MAINTAINING THE VISCGSITY F SULUTIZER SALT SOLUTIONS Bruce C. Phenix, Jr., Dorriss H. Merchant, and Gwen R.

Mitchell, Beaumont, Tex., assignors to Soeony Mobil Oil Company, Inc., a corporation or New York Filed June 2, 1961, Ser. No. 114,493 7 fllaims. (Cl. 208-434) The present invention relates to the extraction of mercaptans from hydrocarbon mixtures with aqueous solutions of alkali metal hydroxide containing alkali metal salt of at least one solutizer and, more particularly, to the extraction of mercaptans from hydrocarbon mixtures employing 1) the cresylate phase of a mixture of alkali metal hydroxide alkyl phenols (cresols), and water in proportions to produce a mixture which at a temperature within the range of about 60 F. and about 150 F. separates into a cresylate phase and a heterogeneous hydroxide phase and (2) a two phase or heterogeneous mixture of alkali metal hydroxide, alkyl phenols (ere-- sols), and water in proportions to produce a mixture which at a temperature within the range of about 60 F. and about 150 F. separates into a cresylate phase and a hydroxide phase.

The use of the aforesaid cresylate phase and the afore' said heterogeneous mixture as agents for the extraction of mercaptans from hydrocarbon mixtures is disclosed in the United States Letters Patent No. 2,850,434, issued September 2, 1958, to Frank W. Brooks, Jr. and Claiborne A. Duval, Jr. These patentees have disclosed that mercaptans can be removed from hydrocarbon fluids by extraction of the mercaptans with (l) a cresylate extraction agent consisting essentially of the cresylate phase of a liquid mixture comprising alkali metal hydroxide, cresols extracted from petroleum fractions boiling within the range of about 105 F. to about 650 F., and water in proportions to form at a temperature within the range of about 60 F. and about 150 F. a cresylate phase com- United States Patent 0 prising of alkali metal cresylates, alkali metal hydroxide,

and water, and a mutually substantially immiscible hydroxide phase comprising alkali metal hydroxide and water, or (2) a heterogeneous extraction agent comprising a two phase liquid mixture comprising alkali metal hydroxide, cresols extracted from petroleum fractions boiling in the range about 105 F. and about 650 F., and water in proportions to form at a temperature within the range of about 60 to about 150 F. a cresylate phase and a mutally substantially immiscible hydroxide phase. These patentees also disclose that mercaptans can be removed from hydrocarbon fluids by extraction with (3) solutizer salt phase extracting agent being the solutizer salt phase of a heterogeneous two phase mixture of a solutizer other than the aforesaid cresols, alkali metal hydroxide and water in proportions to form a solutizer salt phase mutually substantially immiscible with a hydroxide phase at a temperature within the range of about 60 F. to about 150 F., or (4) a two phase or heterogeneous extraction agent being a mixture of a solutizer other than the aforesaid cresols, alkali metal hydroxide, and water in proportions to form a solutizer salt 3,100,744 Patented Aug. 13, 1963 phase substantially immiscible with a hydroxide phase at a temperature within the range of about 60 and about 150 -F. These patentees disclosedtthat the solutizer salt phase of these latter extraction agents are solid andcan be made fluid by admixing (1) theaforedescribed cresols or (2) alcohols or water soluble ketones in amount to make the solid solutizer salt phase fluid but not miscible with the hydroxide phase.

In accordance with the method of extracting mercaptans from hydrocarbon fluids described in the aforesaid US. Patent No. 2,850,434, the extraction agent is regenerated by expulsion of the mercaptans and recycled to the extraction stage. It has now been discovered that when employing the extraction agents 1, 2, 3 or 4 briefly described hereinbefore for the extraction of mercaptans from hydrocarbon fluids, the viscosity of the cresol-containing extraction agent increases with use until the viscosity of the cresol-containing extraction agent has increased to such an extent that operating difliculties, such as the formation of emulsions, the fouling of heat exchangers, valves and piping, are encountered. These difficulties have required the replacement of a cresylate phase extraction agent at a cost within the range of $20,000 to $40,000. Thus, a cresylate phase extraction agent comprising potassium hydroxide, cresols and water initially had a viscosity (SUS at F.) of about 300; after 30 months 'use in extracting 27,000,000 barrels of gasoline it had a viscosity (SUS at 100 F.) greater than 700 SUS at 100 F. A similar cresylate extraction agent which originally hada viscosity of 280 SUS at 100 F., after treating 20,000,000 barrels of gasoline to remove mercaptans had a viscosity of 900 SUS at 100 F.

While a cresylate extraction agent which has a viscosity of 700 SUS at 100 F. is not inoperative because of the formation of emulsions, and fouling of heat exchangers, valves, and piping, nevertheless for substantially trouble-free operation of unit for the extraction of mercaptans from hydrocarbon fluids with any one of the aforedescribed extraction agents and regeneration of the extraction agent, the viscosity preferably is not greater than about 300 to 400 SUS at 100 F.

It has been found that even when the hydrocarbon fluid from which mercaptans are to be extracted with one of the aforedescribed extraction agents is first washed with 20 to 30 percent by weight aqueous alkali metal hydroxide the viscosity of the cresol-containing extraction agent increases to an intolerable extent. Consequently, the problem of the increasing viscosity of cresol-containing extraction agents and the concomitant operating diftficulties requires solution.

It has been found that the increase in the viscosity of cresol-containing aqueous alkaline extraction agents comprising alkali metal hydroxide, water and cresols extracted from petroleum fractions boiling within the range of about F. and about 650 F. is due to a considerable extent, if not entirely, to the increase in the concentration of xylenols in the cresylate phase of the mixture. This correlation is clearly established by the data presented in Table l and graphically illustrated in FIGURE I of the drawings. U r

Table I Table II Cresol-containing extraction agent No. 1 2 1 3 4 5 Maximum Minimum Com csit'on ercent b Wei ht: 5 Tolerable viscosity SUS at 100 F 700 No limit.

v i ater nff 23. 4 30.3 32.2 36.6 38.7 Preferred viscosity, sUs at 100 About 300 to 400-. Do. Potassium hydroxide. 35.0 36.0 37.0 39.0 40.0 Usual viscosity of fresh crcsylate bout 350 About 300. Total organic acids L 41. 33. 7 30. 8 24. 4 21. 3 treating agent SUS at 100 1?. Xylenols 17. 0 11.1 7. 9 2. 0 Preferred viscosity for industrial on About 300 to 400.- N 0 limit. Distributi nofphenols in total organic timum extraction of megcaptans acids, percent by weight: from gasoline, SUS at 100 F.

Phenol 10.7 34.6 17.5 18.2 100.0 Xylenol concentration in crcsylate Not more than 15.. Zero. Orcsols. 48. 5 38. 2 56. 7 71. 5 10 phase to produce preferred viscos- Xylenols 40. 8 27. 2 25. 8 10. 3 ity, weight percent. Viscosity of extraction agent SUS at V Xylenol concentration in cresylate About Do.

100 F .1 722 368 306 202 3 90 phase for industrial optimum extraction of mercaptans from gasoline, Weight percent. Oresol-containing extraction agent No 1 3 4 15 3 3 346 The foregoing statements apply with equal force and 23 367 effect to heterogeneous crcsylate treating agents when the 402 2 g amount of alkali metal hydroxide solution in the heter- 1222 3 2 ogeneous mixed treating agent does not exceed that necessary to overcome the small dilution produced by neutrali 65% total organic acids of extraction agent No. 1 and 35% total organic The data presented in Table I are plotted (1) on the basis of the concentration of the xylenols in the cresols of the total crcsylate phase and (2) on the basis of the concentration of xylenols in the total crcsylate phases. It will be observed that as the concentration of xylenols in the total crcsylate phase is reduced from about 17 percent, equivalent to about 40.8 percent in the cresols of the crcsylate phase, the viscosity is reduced to about 200 SUS at 100 F. when the concentration of xylenols in the total crcsylate phase is about 2.5 percent equivalent to 10 percent by weight of the cresols in the crcsylate phase.

In general, a treating agent having a maximum viscosity at 100 F. of about 300 to about 400 SUS is preferred. However, a maximum viscosity at 100 F. of about 700 SUS (Saybolt Universal seconds) can be tol erated. The minimum viscosity can be as low as local conditions permit. Usually, the viscosity of fresh crcsylate phase treating agent is about 300 to about 350 SUS ization of the alkali metal hydroxide by the mercaptans extracted from the gasoline.

The aged alkali metal crcsylate phase treating agent can be treated to reduce the viscosity thereof as illustrated by the data presented in Table III and graphically presented in FIGURES 2 and 3. A high viscosity potassium crcsylate phase treating agent having a viscosity at 100 F. of 722 SUS Was treated to reduce the viscosity thereof by the addition of various amounts of (A) the potassium salts of cresols having an end boiling point of 400 F., (B) potassium salts of cresols having an end boiling point of 403 F. and (C) by mixing phenol with a mixture of the crcsylate phase treating agent and sufiicient additional potassium hydroxide to neutralize the added phenol.

It will be observed that the addition of A (supra) in amount to be 31 percent by weight of the modified treating agent reduced the viscosity at 100 F. from'722 SUS to 521 SUS. The addition of B (supra) in the amount to be 52 percent by weight of the modified treating agent reduced the viscosity at 100 F. from 722 SUS to 441 SUS. The addition of phenol (present as potassium phenate) in the amount to be 35 percent by weight of the modified treating agent reduced the viscosity at 100 F. from 722SUS to 368 SUS.

Table III Blend components Blend numbers High viscosity crcsylate treating agent, percent by weight Oresylate from Gresols EBP of 400 F., percent by weight Oresylate from Cresols EBP of 403 F.. percent by Weight Oresylate from Phenol} percent by Weight.

1 Treating agent prepared from phenol contains potassium phenate which is a solid at room temperature.

578 524 ass 0 o -5 50.0 16.3 14.5 11.1

To ensure the formation of a liquid treating agent, the phenol is admixed with the crcsylate treating agent and the alkali metal hydroxide, for this illustration otassium h droxide do to h blend to produce a treating agent substantially immiscible with 50 Baume aqueous potassium hydroxide. p y ad d t e 2 In aqueous crcsylate phase. a Charted viscosity equivalent to phenol modifier in acid phase.

at 100 F. The maximum concentration of xylenols in the crcsylate phase of a treating agent should not exceed about 15 to 17. percent by weight for the preferred viscosity of 300 to 400 SUS at 100 F. The foregoing is tabulated in Table II.

In FIGURE 2 the viscosities of the various modified treating agents have been plotted against the percent by Weight of modifying acidic organic material (salt solution) added to the high viscosity aged crcsylate phase treating agent. It will be observed that phenol as a modifying agent is more effective than either cresols having an end boiling point of 400 F. or cresols having an end boiling point of 403 F. It will also be observed that the cresols having an end boiling point of 400 F. are more eifective in reducing the viscosity of the high viscosity cresylate phase treating agent than are the cresols having an end boiling point of 403 F.

In FIGURE 3 the viscosities of the modified treating agents have been plotted against the concentration of xylenols in the total cresylate phase. It will be observed that the curves for the viscosity versus the concentration of xylenols when the modified treating agent is prepared by the addition of phenol or of cresols having end boiling points of 400 F. and 403 F. are substantially parallel.

As has been stated in Table II, the preferred viscosity of the cresylate phase in equilibrium with 50 Baum potassium hydroxide is inthe range of about 300 to about 400 SUS at 100 F. Thecu rves FIGURE 3 establish that a viscosity of 300 to 400 SUS at 100 F. is obtained when said cresylate phase contains about 12 percent by weight of xylenols and the balance substantially cresols other than xylenols. On the other hand, it has been stated in Table II that the maximum concentration of xylenols for industrial operation is about 15 percent by weight. It has also been set forth in Table II that a viscosity of 700 SUS at 100 F. can be tolerated. The curves in FIGURE 3 clearly show that the optimum concentration of xylenols, 15 percent by weight, is correlated with a cresylate phase viscosity of about 560 to about 600 SUS at 100 F. Accordingly, when the viscosity of the cresylate phase of used treating agent exceeds 600 SUS at 100 F. and preferably 400 SUS at 100 F., the cresylate phase is diluted with phenols containing a lower concentration of xylenols than that of the cresylate phase of the used treating agent to reduce the viscosity of the modified, i.e., diluted, cresylate phase to not more than about 600 SUS at 100 F. and preferably to not more than 400 SUS at 100 F. while maintaining the xylenol concentration in the cresylate phase of the modified treating agent in the range of about to percent by weight and preferably in the range 7 to 15 percent by weight and the balance substantially phenols other than xylenols. The modified treating agent then has a cresylate phase comprising not more than 15 percent by weight and not less than about 7 percent by weight and preferably about 10 to about 15 percent by weight xylenols balance to make 100 percent of the cresylate phase substantially phenols. (The phrase cresylate phase has been used herein-before and is used hereinafter to designate (1) the cresylate phase of a heterogeneous treating agent comprising alkali metal hydroxide, phenols, and water in the proportion that at a temperature in the range of about 60 F. to about 150 F. separates into a cresylate phase and a hydroxide phase, (2) the homogeneous treating agent comprising the cresylate phase only of the aforesaid 1) heterogeneous treating agent, (3) the sol-utizer salt phase of a heterogeneous treating agent comprising a mixture of alkali metal salts of at least one solutizer other than cresols, alkali metal hydroxide, and water in proportions that at a temperature in the range of about 60 F. to about 150 F. separates into a solutizer salt phase and a hydroxide phase and containing an amount of alkali metal salt of cresols to maintain the aforesaid solutizer salt phase liquid in the range of about 60 F. to about 150 F, and (4) the homogeneous treating agent comprising the solutizer salt phase only of the aforesaid (3) heterogeneous treating agent.) The concentration of xylenols is the percent by weight of that phenol in the mixture not of the theoretical alkali metal salt of that phenol.

Accordingly, the present invention provides in a cycle manner preparing a fresh treating agent comprising alkali metal hydroxide, alkali metal salt of phenols including xylenols, and water which at a temperature in the range of about 60 F. and about 150 F. separates into a cresylate phase and a hydroxide phase, said cresylate phase containing not more than 15 percent by weight and not less than about 7 percent by weight of xylenols and when in equilibrium with 50 Baum aqueous alkali metal hydroxide said cresylate phase has a viscosity in the range of about 300 to about 400 SUS at F., extracting mercaptans from hydrocarbon mixtures with (1) the aforesaid cresylate phase and the aforesaid hydroxide phase or (2) with the aforesaid cresylate phase only to obtain fouled treating agent, regenerating said fouled treating agent by steam distillation, fortifyin-g said cresylate phase with respect to the concentration of alkali metal hydroxide, extracting mercaptans from hydrocarbon mixtures with the said regenerated and fortified aged treating agent until when the cresylate phase of said treating agent is in equilibrium with 5 0 Baum aqueous alkali metal hydroxide the viscosity of said cresylate phase exceeds 700 SUS at 100 F., preferably When the SUS at 100 F.. exceeds 600, diluting the cresylate phase with phenols having a concentration of xylenols less than that of the aforesaid aged treating agent and preferably less than 7 percent by weight including phenols substantially devoid of xylenols, to provide a modified treating agent the cresylate phase of which has a viscosity at 100 F. not greater than 600 SUS and preferably not greater than 400 SUS and contains not more than 15 percent by weight of xylenols and preferably about 10 to about 15 percent by weight xylenols the balance to make 100 percent by weight of the organic material neutralizable with alkali metal hydroxide being phenols other than xylenols boiling below about 650 F., and extracting mercaptans from hydrocarbon mixtures with the aforesaid modified treating agent whilst maintaining the viscosity at 100 F. not greater than 600 SUS and the xylenol concentration not greater than 15 percent by weight but not less than about 7 percent by weight of the neutralizable organic material in the regenerated, fortified treating agent.

For illustrative purposes the following characteristics of the cresylate phase of a treating agent comprising phenols, potassium hydroxide, and water are given in Table IV.

We claim:

1. In the treatment of hydrocarbon mixtures containing mercaptans wherein a hydrocarbon mixture containing mercaptans is contacted with a treating agent having the capabilities of extracting mercaptans and comprising a cresylate phase havinga viscosity at 100 F. of about 300 to about 400 SUS to obtain a fouled treating agent, regenerating said cresylate phase by steam distillation, and extracting mercaptans from hydrocarbon mixture, and wherein the viscosity at 100 F. of said cresylate phase after aging by use increases to greater than about 700 SUS at 100 F. and the xylenol concentration in the neutralizable organic material in the aged cresylate phase increases to more than 15 percent by weight, the improvement which comprises diluting said cresylate phase with at least one phenol having a concentration of xylenols less than that of the aforesaid aged cresylate phase to provide a modified treating agent the cresylate phase of which has a viscosity at 100 P. not greater than about 600 SUS when in equilibrium with 50 Baum alkali metal hydroxide and a xylenol content not in excess of 15 percent by weight of the neutralizable organic material.

2. The method set forth in claim 1 wherein the viscosity 7 of the cresylate phase is reduced to not more than about 500 SUS at 100 F.

3. The method set forth in claim 1 wherein the viscosity of the cresylate phase is reduced to not more than 400 SUS at 100 -F.

4. The method set forth in claim 1 wherein the viscosity of the cresylate phase is reduced to not more than about 600 SUS at 100 F. and the concentration of xylenols to in the range of about 7 to about 15 percent by weight of the neutralizable organic material in said cresylate phase.

5. The method set forth in claim 1 wherein the viscosity of the cresylate phase is reduced to not more than about 600 SUS at 100 F. by dilution with cresols having an end boiling point not higher than about 400 F.

6. The method set forth in claim 1 wherein the viscosity of the cresylate phase is reduced to not more than about 600 SUS at 100 F. by dilution with a mixture of 8 cresols having an end boiling point not higher than about 403 F.

7. In the treatment of mercaptan-containing hydrocarbon mixtures to extract mercaptans therefrom using as extracting medium an agent comprising cresylate, alkali metal hydroxide, and water, said agent also containing xylenols, and wherein the viscosity of the agent increases with use'to a value greater than 700 SUS at 100 F., the improvement comprising decreasing the viscosity of the agent to less than 700 SUS at 100 F., by adding to the agent a diluent comprising phenols having a xylenol con tent less than that of said agent.

References Cited in the file of this patent UNITED STATES PATENTS Duval Sept. 12,.19 61

Claims (1)

1. IN THE TREATMENT OF HYDROCARBON MIXTURES CONTAINING MERCAPTANS WHEREIN A HYDROCARBON MIXTURE CONTAINING MERCAPTANS IS CONTACTED WITH A TREATING AGENT HAVING THE CAPABILITIES OF EXTRACTING MERCAPTANS AND COMPRISING A CRESYLATE PHASE HAVING A VISCOSITY AT 100*F. OF ABOUT 300 TO ABOUT 400 SUS TO OBTAIN A FOULED TREATING AGENT, REGENERATING SAID CRESYLATE PHASE BY STEAM DISTILLATION, AND EXTRACTING MERCAPTANS FROM HYDROCARBON MIXTURE, AND WHEREIN THE VISCOSITY AT 100*F. OF SAID CRESYLATE PHASE AFTER AGING BY USE INCREASES TO GREATER THAN ABOUT 700 SUS AT 100*F. AND THE XYENOL CONCENTRATION IN THE NEUTRALIZABLE ORGANIC MATERIAL IN THE AGED CRESYLATE PHASE INCREASES TO MORE THAN 15 PERCENT BY WEIGHT, THE IMPROVEMENT WHICH COMPRISES DILUTING SAID CRESYLATE PHASE WITH

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