US 3666660 A
Polynuclear aromatic hydrocarbons, and other aromatic compounds and organic sulfur and nitrogen compounds are removed as impurities from petroleum streams by extraction with Cr<+++> in a solution of acetone, methanol or ethanol wherein the metal ion complexes with the impurities and is withdrawn with the metal salt solution.
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United States Patent [151 3,666,660 Bernheimer 1 May 30, 1972  PURIFICATION OF A HYDROCARBON 1.826.142 10/1931 Lachman ..20s 295 STREAM WITH CR IONS IN SOLUTION  Inventor: Ralph Bernhelmer, East Brunswick, NJ.
 Assignee: Esso Research and Engineering Company  Filed: Apr. 30, 1970  Appl. No.: 33,481
 US. Cl ..208/243  Int. Cl ..Cl0g 29/06  Field of Search ..208/243, 244,246, 226, 232,
 References Cited UNITED STATES PATENTS 3,326,798 6/1967 Hess ..208/246 FOREIGN PATENTS OR APPLICATIONS Great Britain ..208/295 Canada ..208/232 Primary Examiner-Delbert E. Gantz Assistant Examiner-G. J. Crasanakis AtrorneyPearlman and Schlager and C. D. Stores [5 7] ABSTRACT 1 Claim. No Drawings PURIFICATION OF A HY DROCARBON STREAM WITH CR IONS IN SOLUTION BACKGROUND OF THE INVENTION This invention relates to the removal of impurities from petroleum fractions and more particularly relates to the removal of polynuclear aromatic hydrocarbons, sulfur compounds and nitrogen compounds as impurities from hydrocarbons.
The problem of nitrogen and sulfur removal is particularly important in the petroleum industry. Sulfur occurs, generally, in the form of mercaptans, sulfides, disulfides, thiophenes, benzothiophene, and dibenzothiophene. Nitrogen compounds are usually present as heteroatomic organic compounds, such as pyridines, pyrroles, quinolines, pyrindines, cyclopentaquinolines, indoles, carbazoles, pyrrologuinones, etc.
These nitrogen and sulfur compounds adversely affect many of the important refining processes. They are believed to reduce the activity of cracking or hydrocracking catalysts because of their polarity and basicity. They are also suspected of being involved in gum formation, color formaiton, odor and poor storage properties of fuels.
The polynuclear aromatics, besides being carcinogenic, appear to be color precursors and hence their presence also has bearing on color and color stability problems of lubricating oils.
SUMMARY OF THE INVENTION In accordance with the present invention the above difiiculties can be overcome by extracting the polynuclear aromatic hydrocarbons as well as other aromatic compounds, organic sulfur and organic nitrogen compounds from various hydrocarbon streams by means of solutions of metal ions. The petroleum fractions containing the impurities are contacted with the salt solutions whereby metal complexes form which can be removed with the solvent phase. Many metals and many solutions are effective but the transition metals, Fe Cu, and Cr as well as Li are most effective. The most effective solvents are ethanol and acetone.
Such extraction systems are advantageous because of the low cost of the raw materials, because the solvent and metal salt are recoverable and the use of a simple counter-current extraction unit employing recycle will drive the system to completion.
PREFERRED EMBODIMENTS Feed streams suitable for use in this invention include any type of petroleum stream, e.g. light fractions such as naphthas, lubricating oil fractions, and heavy fractions such as petroleum residua and tars, in short, any hydrocarbon stream containing polynuclear aromatic hydrocarbons, and/or nitrogen and sulfur compounds.
The invention is particularly directed to the removal of impurities, particularly nitrogen and sulfur impurities from the above streams by the use of solutions of metal salts. Suitable metal salts include those of Groups 18, IIB, VIB, and VIII of the Periodic System (E. H. Sargent and Company, 1952) and lithium, e.g. Cr(NO FeCl nickelous acetate, nickelic acetate, Ca( N AgNO HgNO and LiBr.
Suitable solvents include any oxygenated and/or nitrogen based solvents, i.e. any highly polar solvent, e.g. water, acetic acid, acetone, ethyl alcohol, methyl alcohol, tetrahydrofuran, furan, and peracetic acid. Water may be mixed with the solvent in proportions of from 100 parts solvent to 1 of water to 1 part solvent to 3 of water.
The preferred metal ions are Fe Cu, Cr**"', and Li The preferred solvents are methanol, ethanol, and acetone.
The solvent to hydrocarbon feed ratio may vary from 1:100 through 1:! to :1.
The process is independent of pressure and therefore is best carried out at atmospheric pressure unless some specific reason dictates higher pressures. The temperature chosen will also, in general, be room temperature, although higher temperatures may be used. In general, complex formation of polynuclear aromatic hydrocarbons with the salts will be promoted by room temperature and slightly above. Complex formation of sulfur and nitrogen compounds may in some instances be favored by higher temperatures.
The following examples are presented as specific embodiments of the invention but without any intention of limiting the invention thereto.
EXAMPLE 1 To an aromatic sievate obtained by passing a light petroleum fraction through a 5 Angstrom molecular sieve was added 1.0 ppm 3,4-benzpyrene (C labeled). Separate lOO ml samples of this mixture were extracted with various salt solutions and the amounts of benzpyrene determined by C counting. The following results were obtained:
% 3,4 Benzpyrene Removed Salt Solvent 24 48 72 96 I66 I-Ir. Hr. Hr. Hr. Hr.
Cr( N0 H O l 0 FeCl CH;,COCH 25 28 24 Cr( N0 Cl l COCl-l 60 Ni(OAc); CH CH OH l8 LiBr CH COCH 38 35 LiBr Tetrahydrofuran 6| 9 Ni( OAc CH COCI-I; 3 6 AgNO Furan 25 8.3
(water added) AgNO, Acetone 42 l 1 Cu( N0 CH COCH 72 64 Cr( N0 CH COCH 58 Cu(NO CH CO OH l 7 FeCl CH;,CH OH 15 Ni( OAc) CH= CH OH l 8 Ni(OAc) (Cl-l: );CO 3 6 LiBr CH CI-l Ol-I 8 HgNO CH OI-I l4 19 26 FeCl CH Ol-l 7 FeCl Acetone 35 34 FeCl Cl-l OI-l 5 Co( OAc) CH Ol-l 6 7 Co( OAc) Acetone 38 37 Cu( N0 Acetone 65 72 (green) Cu( N0 Acetone 52 63 73 (blue) .Cr( NQ, Acetone 53 58 62 '0Ac= acetate.
The above data show that all the metals listed and all the solvents except water are operable but that Fe Cu, Cr and Li are most effective when used with ethanol and acetone solvents.
EXAMPLE 2 Two percent solutions of each of the four compounds: (A) 1,2-diphenylethane; (B) dibutylmaleate; (C) dimethyl pyridine; and (D) benzophenone were added to the sievate used in Example l. Twenty-five ml. of each of these solutions were mixed with 25 ml. of various salt solutions and placed in 2 oz. bottles, sealed and shaken for about 12-14 hours on a mechanical shaker for an elapsed time of 48 hours. Five ml. samples were removed by pipette and separated into raflinate and salt phase layers in calibrated graduated flasks. The efficiency of the extraction was calculated by U.V. analysis. The following results were obtained:
l ,Z-DIPHENYLETI-IANE Salt Solvent %Compound Removed Cu( NO, Acetone 4.3 Cu( N0, Ethanol 19.1 Cu(NQQ, Methanol 8.6 Cu( N: )1 H 0 1 2.8 V Cr( NO, Acetone 0.0 Cr( N0 Ethanol 23.0 LiBr Acetone 0.0 LiBr Ethanol l 6.8 FeCl, Acetone 19. l FeCl, Methanol 8. l l-eCl; Ethanol 26.2
DIBUTYLMALEATE Salt Solvent %Compound Removed Cu( NO Acetone 27.0 Cu(NO, Ethanol 7 l .7 Cu(NOg; Methanol 42.0 Cu( NO, H 0 4.8 Cr( NO, Acetone 25.0 Cr( NO, Ethanol 64.3 LiBr. Acetone 20.8 LiBr Ethanol 84.5 FeCl, Acetone 68.8 FeCl, Ethanol 80.9
DIMETHYL PYRIDINE Salt Solvent %Compound Removed Cu( NO, Acetone 96.9 Cu( N0 Ethanol 99.9 Cu( N0 Methanol 99.9 Cu(NO 11,0 98.5 Cr( NO Acetone 95.4 Cr(NOfl Ethanol 99+ LiBr Acetone S 6.4 Li Br Ethanol 87.6 FeCl Acetone 98.9 FeCl Ethanol 99. 3
BENZOPHENONE Salt Solvent %Compound Removed Cu( N0 Acetone 67.0 Cu( N0 Ethanol 7 l .2 Cu( N0 Methanol 58.0 Cr( N0 Acetone 75.1 Cr( NO, Ethanol 67.7 LiBr Acetone 73.9 LiBr Ethanol 83.8
Fe-Cl FeCl Acetone Ethanol EXAMPLE 3 Hydrocarbon solutions of thiophene and dibutyl sulfide were extracted, with various salt solutions and the percent sulfur removed was determined by the Dohrmann microcoulometer. The following results were obtained:
Compound Salt Solvent Removed Thiophene in Octane Nal Acetone 3 3 .7 Thiophene in Benzene Cu( N0 )2 Methanol 23 8 Thiophene in Benzene Cu( NO; Ethanol 23.8 Thiophene in Rafi'inate( l) Cu(NO Acetone 43 .7 Thiophene in Rafi'inate( l Cu( N09 Acetone 45 .6 Thiophene in Benzene LiBr Acetone 19.0 Thiophene in Benzene Li Br Acetone 24.4 Thiophene in Benzene Cu( N0 Acetone 52. l Thiophene in Benzene LiBr Acetone 55.3 Dibutyl Sulfide in Benzene Cu( N0 Acetone 36.4 Dibutyl Sulfide in Sievate Cu(NOQ; Acetone 52.0 Dibutyl Sulfide in Sievate Cr( N0 Ethanol 26.0 Thiophene in Sievate Cr( N09 Ethanol 42.0
The sievate ofExample l.
The above data show that sulfur compounds can be satisfactorily removed from hydrocarbon solutions.
The nature and advantages of the present invention having thus been fully set forth and specific examples of the same given what is claimed as new, useful and unobvious and desired to be secured by Letters Patent is:
1. A process for removing polynuclear aromatic hydrocarbons, organic sulfur compounds or organic nitrogen compounds from any hydrocarbon stream, which comprises contacting said stream with Cr" ions in a solution of acetone, methanol or ethanol.