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Publication numberUS3902859 A
Publication typeGrant
Publication dateSep 2, 1975
Filing dateApr 1, 1974
Priority dateFeb 15, 1973
Publication numberUS 3902859 A, US 3902859A, US-A-3902859, US3902859 A, US3902859A
InventorsNicholas P Greco
Original AssigneeKoppers Co Inc
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Method for separating ammonium sulfate from an aqueous solution of ammonium bisulfate and ammonium sulfate
US 3902859 A
Abstract
A method is disclosed for separating ammonium sulfate from an aqueous solution of ammonium bisulfate and ammonium sulfate, and, in particular, where the aqueous solution additionally contains organics from a synthesis reaction. Separation is effected by the addition of an alcohol, preferably methanol, to the aqueous solution in an amount sufficient to precipitate substantially all of the ammonium sulfate and thereafter removing said precipitate from the solution.
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United States Patent [1 1 Greco 1 51 Sept. 2, 1975 METHOD FOR SEPARATING AMMONIUM SULFATE FROM AN AQUEOUS SOLUTION OF AMMONIUM BISULFATE AND AMMONIUM SULFATE [75] Inventor. Nicholas P. (ireco, Pittsburgh. Pa.

[73] Assignee: Koppers Company. Inc.. Pittsburgh.

abandoned.

[52] U.S. Cl. 23/296; 23/300; 23/302 A; 423/520; 423/545 [51] Int. Cl. BOID 9/02; C01C 1/24 [58] Field of Search 23/296, 299. 300, 302, 23/302 A; 423/517. 520. 545

[56] References Cited I UNITED STATES PATENTS 2.002.797 5/1935 Reich 23/302 A 2.013.438 9/1935 Fitz 23/302 A 2.386.985 10/1945 Shaw 23/302 A 2.666.687 l/l954 Skinner 23/300 3.366.681 l/1968 Thoma ct al 23/302 A 3.408.157 10/1968 Miller ct alt 23/302 A 3.549.706 12/1972 Takaki ct al 23/302 A 3.576.607 4/1971 Guttmann ct al 23/300 3.597.168 8/1971 Hoppc ct a1. 23/302 A 3.709.666 1/1973 Westerveld ct a1 23/302 A FOREIGN PATENTS OR APPLICATIONS 205540 5/1956 Australia 23/302 A OTHER PUBLICATIONS Seidell. Solubility of lnorg. and Org. Cds.. Vol. 1. 1919. pages 63 to 66.

Primary E.\'uminrN0rman Yudkoff Assistant E.\'aminerS. J. Emery Attorney, Agent. or Firm-Robert D. Yeager [57] ABSTRACT A method is disclosed for separating ammonium sulfate from an aqueous solution of ammonium bisulfate and ammonium sulfate. and. in particular. where the aqueous solution additionally contains organics from a synthesis reaction. Separation is effected by the addition of an alcohol. preferably methanol. to the aqueous solution in an amount sufficient to precipitate substantially all of the ammonium sulfate and thereafter removing said precipitate from the solution.

4 Claims, N0 Drawings METHOD FOR SEPARA'IING AMMONIUM SULFATE FROM AN AQUEOUS SOLUTION ()F AMMONIUM BISULFATE AND AMMONIUM SULFATE This is a continuation. of application Ser. No. 332,668. filed Feb. 15. l973 now abandoned.

FIELD OF THE INVENTION The present invention relates to a method for separating ammonium sulfate from ammonium bisulfate. and. in particular. to a method of separating ammonium sulfate from an aqueous solution containing ammonium bisulfate and organic synthesis material.

BACKGROUND OF THE INVENTION It has recently been found that certain organic synthesis can be carried out by utilizing ammonium bisulfate. In many of these reactions, ammonium sulfate is formed as a byproduct that must either be disposed of or regenerated. Because the disposal problem is now becoming inherently more difficult to deal with. it is highly desirable to regenerate ammonium bisulfate therefrom. Not only does regeneration effectively avoid or eliminate the disposal problem. it also renders the organic synthesis more economical.

Also, in many of the synthesis reactions. excess quantities of ammonium bisulfate are preferred or required. In these reactions. not only is ammonium sulfate a byproduct. but it is usually found with the excess quantities of ammonium bisulfate and certain unreacted or partially reacted organics utilized in the synthesis reaction. Various methods of regeneration have recently been proposed. One such method first removes the organics found in the aqueous solution of ammonium bisulfate and ammonium sulfate to prevent undesirable foaming. Thereafter. a fused mixture of ammonium bisulfate and ammonium sulfate is prepared which is contacted with hot sweep gases to convert the ammonium sulfate to bisulfate.

While this method performs well and provides efficient regeneration of ammonium sulfate to bisulfate. it does require apparatus for handling large quantities of ammonium bisulfate that does not need to be regenerated. Accordingly, it is desirable to have a method which preferentially separates the ammonium sulfate and organics from the aqueous solution containing them as well as ammonium bisulfate.

SUMMARY OF THE INVENTION The present invention provides a method for separating ammonium sulfate from an aqueous solution containing same and ammonium bisulfate. The method of the present invention also provides for removing organics present in the aqueous solution of ammonium bisulfate.

Generally, the method of the present invention comprises adding to an aqueous solution of ammonium bisulfate. ammonium sulfate, and residual organics. if any. an alcohol. preferably methanol. The addition of alcohol preferentially causes the precipitation of all of the ammonium sulfate from the aqueous solution. Preferably. the ammonium sulfate is thereafter filtered and the filtered solids washed with an alcohol. preferably methanol. to clean any of the organics present thereon. The organics dissolved by the alcohol can be recovered after recovering the alcohol by distillation and recycled. if desired. back to the synthesis reaction together with the aqueous ammonium bisulfate solution. Be-

7 cause the method of the present invention provides for the precipitation of substantially pure crystalline ammonium sulfate. the sulfate can be used substantially in precipitated or preferably washed form after drying of methanol as a fertilizer or may be regenerated to ammonium bisulfate by known methods for use in the organic synthesis.

DESCRIPTION OF THE INVENTION Solutions of ammonium bisulfate. ammonium sulfate and. optionally water. from organic synthesis reactions are treated with alcohol. preferably methanol. after the synthesized product has been removed therefrom. Suitable alcohols in addition to methanol include ethanol. butanol, isopropanol. and the like. However. because of the relative cheapness of methanol. it is preferred. The alcohol is added to the aqueous solution preferably in amounts from about 400 to 500% by weight of the amount of ammonium sulfate theoretically present. The temperature at which separation is effective to remove all of the ammonium sulfate present is from pref erably to C.

It may be desirable to concentrate the aqueous solution prior to the sulfate removable. since less alcohol would be required to effectuate precipitation. For instance. in Example 1 below. it was found advantageous to concentrate the raffinate by evaporation of of the water present therein. This provided a more concentrated solution of ammonium sulfate and ammonium bisulfate. With that particular concentration. for

example. substantially all of the ammonium sulfate present was removed by precipitation. That concentration of salt before precipitation is about the minimum concentration possible while maintaining the salt in solution at room temperature.

The following generalized examples more clearly set forth the advantages of the present invention:

EXAMPLE 1 EXAMPLE 2 Example 1 was repeated using methanol for the selective precipitation and recovery of ammonium sulfate from the concentrated raffinate after extraction of the synthesized material. The raffinate was thereafter fortified with ammonium bisulfate in water, an aromatic amine equal in amount to those consumed and recycled. The results of these runs are set forth in the following table:

TABLE Recovery of Ammonium Sulfate From Aqueous Mixtures With Ammonium Bisull'ate Resulting From S \nthetic Reactions Empltning Amines Products (Trude Reactor Charge. gv Product Synthesized g l Annlysig Aromatic Temp.v Recovered ofTh -un "NC. ('yclc Amine NH,HS() (NH.). -S() hrs (1 Yield Salt. 5 as l NHJ SO," (NHJ-SO NH,HS(),

I 32.4 158. 2 47 3 240 27.8 84.2 99.5 901) 9&0 2.0 I 27.3 NH) none 3 330 25.0 )(H) 5L5 035 977 2.3 3 23.7 (ill: 27,7 .1 236 lit-1 73. $547 91.1 93.} I47 4 24.5 57.2 27.7 3 240 22.x v1.2 72.4 x10 9% (t4 5 none none none 2 240 2.] 8.4 Totals 1 12,9 -l-lh l 33. l I} 99.] 861 831 "l HN,);S(), obtained h difference after titration of NH,HS(),i Concentrated lU gnu 73 moles of water per theoretical mole of amine. "Crude as analyletl [n he W 1" product. going Nlh'i corrected \ield. "Assuming l m amine charged gi\ cs 2 m. (NH,

"'A\ g. reumcr mur four cycles What is claimed is:

l. A method for separating ammonium sulfate substantially free of ammonium bisulfate and organic impurities and obtaining a solution of ammonium bisulfate substantially free of any ammonium sulfate from an aqueous solution containing ammonium bisulfate and ammonium sulfate and dissolved organic impurities, said method consisting essentially of concentrating said solution to the maximum possible while maintaining the salts in solution, adding to said aqueous solution an alcohol selected from the group consisting of methanol, ethanol, propanol, butanol, and isopropanol'in an amount of from about 400 to 500 percent by weight of the ammonium sulfate present in the solution and effective to precipitate substantially all of .said ammonium sulfate without precipitating substantially any of the ammonium bisulfate and removing all of said precipitated ammonium sulfate from said solution to obtain a solution of ammonium bisulfate.

2. A method as set forth in claim 1 wherein said alcohol is methanol.

3. A method as set forth in claim 1 wherein said aqueous solution is maintained between about and C.

4. A method for obtaining an aqueous solution of ammonium bisulfate substantially free of ammonium sulfate and any dissolved, and ammonium sulfate substantially free of organic impurities from an aqueous solution containing ammonium bisulfate, ammonium sulfate, and dissolved organic impurities, said method consisting essentially of concentrating said solution to the maximum possible while maintaining the salts in solution, adding to said'concentrated solution an alcohol selected from the group consisting of methanol, ethanol, propanol, butanol, and isopropanol, in an amount of from about 400 to 500 percent by weight of the ammonium sulfate present in the solution and effective to precipitate substantially all of said ammonium sulfate substantially free of ammonium bisulfate and organic impurities, removing said precipitated ammonium sulfate to form a remaining solution. and separating said alcohol from said remaining solution to obtain said aqueous solution of ammonium bisulfate.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION PATENT NO. 3,902,859

DATED September 2, 1975 INVENTOR(S) 1 Nicholas P. Greco It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

[SEAL] Claim 4 should read as follows:

4. A method for obtaining an aqueous solution of ammonium bisulfate substantially free of ammonium sulfate, and ammonium sulfate substantially free of organic impurities from an aqueous solution containing ammonium bisulfate, ammonium sulfate, and dissolved organic impurities, said method consisting essentially of concentrating said solution to the maximum possible while maintaining the salts in solution, adding to said concentrated solution an alcohol selected from the group consisting of methanol, ethanol, propanol, butanol, and isopropanol, in an amount of from about 400 to 500 percent by weight of the ammonium sulfate present in the solution and effective to precipitate substantially all of said ammonium sulfate substantially free of ammonium bisulfate and organic impurities, removing said precipitated ammonium sulfate from solution to form a remaining solution, and separating said alcohol from said remaining solution to obtain said aqueous solution of ammonium bisulfate.

Signed and Sealed this Attest:

RUTH C. MASON Arresting Officer C. MARSHALL DANN Commissioner of Pa ten rs and Trademarks

Patent Citations
Cited PatentFiling datePublication dateApplicantTitle
US2002797 *Oct 21, 1932May 28, 1935Gustave T ReichAlkali metal compound recovery from waste organic mixtures
US2013438 *Dec 23, 1931Sep 3, 1935Koppers Co DelawareRecovery of salts from salt solutions
US2386985 *Oct 11, 1944Oct 16, 1945Koppers Co IncProcess for the recovery of ammonium thiosulphate and thiocyanate
US2666687 *Nov 1, 1948Jan 19, 1954Union Oil CoProcess for the manufacture of crystalline ammonium sulfite monohydrate
US3366681 *Sep 30, 1965Jan 30, 1968StamicarbonProcess for the recovery of methionine
US3408157 *Jun 1, 1966Oct 29, 1968Standard Oil CoProcess for recovery of ammonium salts from process waste streams and disposal thereof
US3549706 *Jul 17, 1969Dec 22, 1970Sumitomo Chemical CoProcess for separating acrylamide
US3576607 *Apr 11, 1968Apr 27, 1971Standard Oil Co OhioProcess for the recovery of ammonium salts from process waste streams
US3597168 *Dec 11, 1968Aug 3, 1971Kali Veb KRecovery of large grains of na2so4 and (nh4)2so4 from aqueous methanol solutions
US3709666 *Oct 20, 1969Jan 9, 1973StamicarbonProcess of recovering ammonium sulphate from an aqueous solution containing ammonium sulphate and methionine
Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US5141732 *Apr 4, 1991Aug 25, 1992Ec Erdolchemie GmbhProcess for the removal of ammonium sulphate from tarrich waste streams from the production of (meth) acrylonitrile
US5973198 *Mar 2, 1998Oct 26, 1999Sumitomo Chemical Company, LimitedMethod for separating ammonium sulfate and ammonium bisulfate from each other and process for producing 2-hydroxy-4-methylthiobutanoic acid utilizing the method
US9102951Aug 24, 2012Aug 11, 2015Iogen Energy CorporationProcess for recovering salt during a lignocellulosic conversion process
US20110044879 *Mar 22, 2007Feb 24, 2011Soos Janos GyoergyProcess for the treatment and purification of dangerous wastes containing ammonium salts, particularly ammonium chloride, derived from pharmaceutical and chemical technologies
EP0126058A1 *May 11, 1984Nov 21, 1984MONSANTO p.l.c.Inorganic salt recovery method
EP0384198A1 *Feb 3, 1990Aug 29, 1990Ec Erdölchemie GmbhProcess for the separation of ammonium sulfate from waste streams with high content of tar coming from the preparation of (meth) acrylonitrile
EP0863135A2 *Mar 4, 1998Sep 9, 1998Sumitomo Metal Industries, Ltd.Method for separating ammonium sulfate and ammonium bisulfate from each other and process for producing 2-hydroxy-4-methylthiobutanoic acid utilizing the method
EP0863135A3 *Mar 4, 1998Dec 9, 1998Sumitomo Metal Industries, Ltd.Method for separating ammonium sulfate and ammonium bisulfate from each other and process for producing 2-hydroxy-4-methylthiobutanoic acid utilizing the method
Classifications
U.S. Classification23/296, 423/545, 23/302.00A, 423/520, 23/300
International ClassificationC01C1/24
Cooperative ClassificationC01C1/24
European ClassificationC01C1/24
Legal Events
DateCodeEventDescription
Sep 25, 1989ASAssignment
Owner name: INDSPEC CHEMICAL CORPORATION
Free format text: CHANGE OF NAME;ASSIGNOR:ISC ACQUISITION COMPANY;REEL/FRAME:005142/0420
Effective date: 19890502
Sep 25, 1989AS01Change of name
Owner name: INDSPEC CHEMICAL CORPORATION
Owner name: ISC ACQUISITION COMPANY
Effective date: 19890502
Jul 31, 1989ASAssignment
Owner name: INDSPEC CHEMICAL CORPORATION
Free format text: CHANGE OF NAME;ASSIGNOR:ISC ACQUISITION COMPANY;REEL/FRAME:005138/0231
Effective date: 19890502
Jan 23, 1989ASAssignment
Owner name: ISC ACQUISITION COMPANY, A CORP. OF DE., PENNSYLVA
Free format text: ASSIGNMENT OF ASSIGNORS INTEREST.;ASSIGNOR:KOPPERS COMPANY, INC.,;REEL/FRAME:005009/0188
Effective date: 19881206
Dec 16, 1988ASAssignment
Owner name: ALGEMENE BANK NEDERLAND N.V., HOUSTON AGENCY
Free format text: SECURITY INTEREST;ASSIGNOR:ISC ACQUISTION COMPANY;REEL/FRAME:004994/0188
Effective date: 19881215