US2729591A - Sweetening of petroleum oils containing mercaptans with alkali and oxygen and then with alkali, a solutizer and oxygen - Google Patents

Sweetening of petroleum oils containing mercaptans with alkali and oxygen and then with alkali, a solutizer and oxygen Download PDF

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US2729591A
US2729591A US294722A US29472252A US2729591A US 2729591 A US2729591 A US 2729591A US 294722 A US294722 A US 294722A US 29472252 A US29472252 A US 29472252A US 2729591 A US2729591 A US 2729591A
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mercaptans
oxygen
alkali solution
oil
disulphides
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US294722A
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Haresnape Dorothy Sylvia
Denyer Ronald Leonard
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BP PLC
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BP PLC
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    • CCHEMISTRY; METALLURGY
    • C10PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10GCRACKING HYDROCARBON OILS; PRODUCTION OF LIQUID HYDROCARBON MIXTURES, e.g. BY DESTRUCTIVE HYDROGENATION, OLIGOMERISATION, POLYMERISATION; RECOVERY OF HYDROCARBON OILS FROM OIL-SHALE, OIL-SAND, OR GASES; REFINING MIXTURES MAINLY CONSISTING OF HYDROCARBONS; REFORMING OF NAPHTHA; MINERAL WAXES
    • C10G27/00Refining of hydrocarbon oils in the absence of hydrogen, by oxidation
    • C10G27/04Refining of hydrocarbon oils in the absence of hydrogen, by oxidation with oxygen or compounds generating oxygen

Definitions

  • solutiser process wherein the oils are contacted with an aqueouscaustic alkali solution containing a substance, such as an alkali metal phenolate or isobutyrate, capable of'increasing the solubility of the mercaptans in
  • This invention relates to the sweetening of petroleum the caustic solution.
  • the caustic solution is regenerated According to the invention therefore, a process for the sweetening of petroleum oils containing mercaptans, con sists in treating the oils with an aqueous caustic alkali solution containing a substance which is capable of increasing thesolubilityof the inercaptans in the alkali,
  • the aqueous caustic alkali solution containing the solubility promoter will heerinafter be referred to as the solutiser solution.
  • the mechanism of the sweetening operation appears to be that the mercaptans first go from the oil phase to the aqueous phase, at which stage both the mercaptan and total sulphur content of the oil are reduced.
  • the mercaptans are oxidised in the aqueous phase, presumably to the insoluble disulphides which then return to the oil phase, thus increasing the sulphur content which gradually returns to its original value while the mercaptan content drops to zero.
  • the caustic solution is thus continuously regenerated so that no separate regeneration process is needed. It is to be understood that the scope of the invention is in no way limited by the above explanation of the mechanism of the reaction.
  • the treatment of the oil with the solutiser solution may advantageously be carried out in two or more stages, all in the presence of oxygen or an oxygen-containing gas.
  • the process of the invention is capable of sweeteninga sour naphtha containing 0.05% by weight mercaptan sulphur.
  • the contact time required is of the order of 20-30 minutes in a two-stage process when giving the naphtha a 50/50 Wash with the solutiser solution.
  • Commercial cresol may conveniently be used as the solubility promoter.
  • a process. of sweetening a petroleum oil containing mercaptans, which comprises mixing the oil with an aqueous caustic alkali solution in the presence of, free oxygen so as to convert part of said mercaptans into disulphides, separating the oil from, the caustic alkali solution, mixing the separated oil in the presence of free oxy gen but in the absence of a catalyst for the oxidation of mercaptans to disulphides with an aqueous caustic alkali solution containing a commercial cresol capable of increasing the solubility of the mercaptans in the alkali solution, so as to client a turther conversion of mercaptans into disulphides, and separating a sweetened oil from the caustic alkali s lu ion.
  • a process of sweetening a petroleum oil containing mercaptans which comprises mixing the oil with an aqueous caustic alkali solution in the presence of free oxygen so as to convert part; of said mercaptans into disulphides, separating the oil from the caustic alkali sohu tion, mixing the separated oil in the. presence of free oxygen but in the absence of a. catalyst for the oxidation of mercaptans to disulphides with an aqueous solution consisting of N NaQH+1.5 N commercial cresol so as to effect a further conversion of mercaptans into disulphides, and separating a sweetened oil from the caustic alkali solution.
  • alkali solution a naphtha containing not more than 0.05% weight mercaptan sulphur, mixing the separated naphtha in the presence of free oxygen but in the absence of a catalyst for the oxidation of mercaptans to disulphides with an aqueous caustic alkali solution containing a substance which is capable of increasing the solubility of the mercaptans in the alkali solution, so as to effect a further conversion of mercaptans into disulphides, and separating a sweetened oil from the caustic alkali solution.
  • a process of sweetening a sour naphtha containing more than 0.05% weight of mercaptan sulphur which comprises mixing the naphtha with an aqueous caustic alkali solution in the presence of free oxygen so as to convert part of said mercaptans into disulphides, separating from the caustic alkali solution a naphtha containing not more than 0.05 weight mercaptan sulphur, mixing the separatednaphtha in the presence of free oxygen but in the absence of a catalyst for the oxidation of necrcaptans to disulphides with an aqueous caustic alkali solution containing a commercial cresol capable of increasing the solubility of the mercaptans in the alkali solution, so as to effect a further conversion of mercaptans into disulphides, and separating a sweetened 'oil from the caustic alkali solution.
  • a process of sweetening a sour naphtha containing more than 0.05% weight of mercaptan sulphur which comprises mixing the napht a with an aqueous caustic alkali solution in the presence of free oxygen so as to convert part of said mercaptans into disulphides, separating from the caustic alkali solution a naphtha containing not more than 0.05% weight mercaptan sulphur, mixing the separated naphtha in the presence of free oxygen but in the absence of a catalyst for the oxidation of mercaptans to disulphides with an aqueous, solution consisting of '5 N NaOH+1.5 N commercial cresol so as to efiect a further conversion of mercaptans into disulphides, and separating a sweetened oil from the caustic alkali solution.

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  • Chemical & Material Sciences (AREA)
  • Oil, Petroleum & Natural Gas (AREA)
  • Engineering & Computer Science (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • General Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Production Of Liquid Hydrocarbon Mixture For Refining Petroleum (AREA)
  • Liquid Carbonaceous Fuels (AREA)
  • Catalysts (AREA)

Description

United States Patent'O SWEETENING OF PETROLEUM OILS CONTAINING MERCAPTANS WITH ALKALI AND OXYGEN AND THEN WITH ALKALI, A SOLUTIZER AND OXYGEN Dorothy Sylvia Haresnape, formerly Macken, and Ronald Leonard Denyer, Sunbury-on-Thames, England, assignors to The British Petroleum Company Limited No Drawing. Application June .20, 1952,.
Serial No. 294,722
Claims priority, application Great Britain July 4, 1951 I 6 Claims. (Cl. 196-29) oils containing mercaptans.
' Among the processes which have been proposed for the removal of mercaptans from petroleum oils is the socalled solutiser process wherein the oils are contacted with an aqueouscaustic alkali solution containing a substance, such as an alkali metal phenolate or isobutyrate, capable of'increasing the solubility of the mercaptans in This inventionrelates to the sweetening of petroleum the caustic solution. The caustic solution is regenerated According to the invention therefore, a process for the sweetening of petroleum oils containing mercaptans, con sists in treating the oils with an aqueous caustic alkali solution containing a substance which is capable of increasing thesolubilityof the inercaptans in the alkali,
solution, in the presence of oxygen or an oxygen-containing gas. The aqueous caustic alkali solution containing the solubility promoter will heerinafter be referred to as the solutiser solution.
The mechanism of the sweetening operation appears to be that the mercaptans first go from the oil phase to the aqueous phase, at which stage both the mercaptan and total sulphur content of the oil are reduced. The mercaptans are oxidised in the aqueous phase, presumably to the insoluble disulphides which then return to the oil phase, thus increasing the sulphur content which gradually returns to its original value while the mercaptan content drops to zero. The caustic solution is thus continuously regenerated so that no separate regeneration process is needed. It is to be understood that the scope of the invention is in no way limited by the above explanation of the mechanism of the reaction.
The treatment of the oil with the solutiser solution may advantageously be carried out in two or more stages, all in the presence of oxygen or an oxygen-containing gas.
It has been found that a considerable conversion of mercaptans to disulphides may be effected by means of an aqueous caustic alkali solution alone, and it is therefore advantageous to treat the oil first with an aqueous caustic alkali solution containing no solubility promoter in the presence of oxygen or an oxygen-containing gas, and then with the solutiser solution likewise in the pres ence of oxygen or an oxygen-containing gas. This method of operation is more economical in the use of solutiser solution and has the further advantage of reducing the time of contact of the oil with th e solutiser solution and thereby considerably improving the colour of the prod uct.
It has been determined that the process of the invention is capable of sweeteninga sour naphtha containing 0.05% by weight mercaptan sulphur. The contact time required is of the order of 20-30 minutes in a two-stage process when giving the naphtha a 50/50 Wash with the solutiser solution. Commercial cresol may conveniently be used as the solubility promoter.
The invention will now be described by way of example asapplied to the continuous sweetening of an unrefined Iranian benzine having a boiling range of l00-150 C and a mercaptan content of 0.05 weight percent.
Two runs were carried out, the first being a treatment with a solutiser solution consisting ofS N NaOH+L5 N cresol and the second with 5. N caustic soda alone. A blanket of oxygen was maintained above the liquid during the whole'of the first run, and the total contact time was initially 30 minutes i. e. 15 in each stage, and was later reduced to 15 minutes and finally to 10 minutes. It was found that with the longer contact times the product was orange in colour probably due: to oxidation products of the cresols. The results of this run are given in the following table and indicate that a contact time of 20-30 minutes is required for a sweet product. The second run using 5 ,N NaOH alone was carried out as a blank experiment; oxygen was again present initially and the total contact time was 30 minutes. For the first 16 hours the product was doctor. negative, but gradually became sour, and finally settled down to a value of 0.002 per cent mercaptan. For the last few hours, the oxygen blanket was replaced by air, the contact time still remaining at 30 minutes. The mercaptan content of the product increased almost immediately, and after 4 hours had reached a value of 0.006 per cent. These results are shown in the table.
TABLE Continuous Z-state washing of unrefined -150 C. Iranian benzine Feedstock:
Conditions:
Rate of feed of spirit... Spirit-reagent ratio Run No M Wash Liquid Contact times:
1st stage 2nd stage Total (J0 at r- 1- cacao Oxygen feed Product from 1st stage:
Mcrcaptan sulphur, wt. percent Product from 2nd stage:
Total sulphur wt. percent. Mereaptan sulphur, wt. percen Acidity ml.N/20 NaOH/lOO ml Exlsteni; Gum mg./l00 ml 2 On On 0. 40 0. 40 trace trace 1 in the absence of a catalyst for the oxidation of mercaptans to disulphides with an aqueous caustic alkali solution containing a substance which is capable of increasing the solubility of the mercaptans in the alkali solution, so as to effect a further conversion of mercaptans into disulphides, and separating a sweetened oil from the caustic alkali solution.
2. A process. of sweetening. a petroleum oil containing mercaptans, which comprises mixing the oil with an aqueous caustic alkali solution in the presence of, free oxygen so as to convert part of said mercaptans into disulphides, separating the oil from, the caustic alkali solution, mixing the separated oil in the presence of free oxy gen but in the absence of a catalyst for the oxidation of mercaptans to disulphides with an aqueous caustic alkali solution containing a commercial cresol capable of increasing the solubility of the mercaptans in the alkali solution, so as to client a turther conversion of mercaptans into disulphides, and separating a sweetened oil from the caustic alkali s lu ion.
3. A process of sweetening a petroleum oil containing mercaptans, which comprises mixing the oil with an aqueous caustic alkali solution in the presence of free oxygen so as to convert part; of said mercaptans into disulphides, separating the oil from the caustic alkali sohu tion, mixing the separated oil in the. presence of free oxygen but in the absence of a. catalyst for the oxidation of mercaptans to disulphides with an aqueous solution consisting of N NaQH+1.5 N commercial cresol so as to effect a further conversion of mercaptans into disulphides, and separating a sweetened oil from the caustic alkali solution.
4. A process of sweetening a sour naphtha Containing more than 0.05%. weight of mercaptan sulphur, which comprises mixing the naphtha with an aqueous caustic alkali solution in the presence of free oxygen so as to convert part of said mercaptans into disulphides, separating from the caustic. alkali solution a naphtha containing not more than 0.05% weight mercaptan sulphur, mixing the separated naphtha in the presence of free oxygen but in the absence of a catalyst for the oxidation of mercaptans to disulphides with an aqueous caustic alkali solution containing a substance which is capable of increasing the solubility of the mercaptans in the alkali solution, so as to effect a further conversion of mercaptans into disulphides, and separating a sweetened oil from the caustic alkali solution.
5. A process of sweetening a sour naphtha containing more than 0.05% weight of mercaptan sulphur, which comprises mixing the naphtha with an aqueous caustic alkali solution in the presence of free oxygen so as to convert part of said mercaptans into disulphides, separating from the caustic alkali solution a naphtha containing not more than 0.05 weight mercaptan sulphur, mixing the separatednaphtha in the presence of free oxygen but in the absence of a catalyst for the oxidation of necrcaptans to disulphides with an aqueous caustic alkali solution containing a commercial cresol capable of increasing the solubility of the mercaptans in the alkali solution, so as to effect a further conversion of mercaptans into disulphides, and separating a sweetened 'oil from the caustic alkali solution.
6. A process of sweetening a sour naphtha containing more than 0.05% weight of mercaptan sulphur, which comprises mixing the napht a with an aqueous caustic alkali solution in the presence of free oxygen so as to convert part of said mercaptans into disulphides, separating from the caustic alkali solution a naphtha containing not more than 0.05% weight mercaptan sulphur, mixing the separated naphtha in the presence of free oxygen but in the absence of a catalyst for the oxidation of mercaptans to disulphides with an aqueous, solution consisting of '5 N NaOH+1.5 N commercial cresol so as to efiect a further conversion of mercaptans into disulphides, and separating a sweetened oil from the caustic alkali solution.
References Cited in the file of this patent UNITED STATES PATENTS 2,413,945 Bolt Jan. 7, 1947 2,427,212 Henderson Sept. 9, 1947 2,474,028 Berger June 21, 1949 2,552,399 Browder' May 8, 1951 2,638,439 Browder et al. May 12, 1953 FOREIGN PATENTS 471,373 Canada Feb. 6, 1951 475,538 Canada July 24, 1951 629,914 Great Britain Sept. 30, 1949

Claims (1)

1. A PROCESS OF SWEETENING A PETROLEUM OIL CONTAINING MERCAPTANS, WHICH COMPRISES MIXING THE OIL WITH AN AQUEOUS CAUSTIC ALKALI SOLUTION IN THE PRESENCE OF FREE OXYGEN, SO AS TO CONVERT PART OF SAID MERCAPTANS INTO DISULPHIDES, SEPARATING THE OIL FROM THE CAUSTIC ALKALI SOLUTION, MIXING THE SEPARATED OIL IN THE PRESENCE OF FREE OXYGEN BUT IN THE ABSENCE OF A CATALYST FOR THE OXIDATION OF MERCAPTANS TO DISULPHIDES WITH AN AQUEOUS CAUSTIC ALKALI SOLUTION CONTAINING A SUBSTANCE WHICH IS CAPABLE OF INCREASING THE SOLUBILITY OF THE MERCAPTANS IN THE ALKALI SOLUTION, SO AS TO EFFECT A FURTHER CONVERSION OF MERCAPTANS INTO DISULPHIDES, AND SEPARATING A SWEETENED OIL FROM THE CAUSTIC ALKALI SOLUTION.
US294722A 1951-07-04 1952-06-20 Sweetening of petroleum oils containing mercaptans with alkali and oxygen and then with alkali, a solutizer and oxygen Expired - Lifetime US2729591A (en)

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GB15827/51A GB728586A (en) 1951-07-04 1951-07-04 Improvements relating to the sweetening of petroleum oils containing mercaptans

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Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3063935A (en) * 1959-09-08 1962-11-13 Shell Oil Co Hydrocarbon sweetening process
US4428828A (en) 1981-01-02 1984-01-31 Chevron Research Company Upgrading hydrocarbonaceous oils with an aqueous liquid
US4481106A (en) * 1983-12-05 1984-11-06 Uop Inc. Hydrocarbon treating process

Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2413945A (en) * 1944-03-09 1947-01-07 Standard Oil Co Treating petroleum distillates
US2427212A (en) * 1944-12-02 1947-09-09 Pure Oil Co Removal of peroxides from hydrocarbon oils
US2474028A (en) * 1946-04-06 1949-06-21 Inventors Guild Recovery of phenol salts from aqueous solutions
GB629914A (en) * 1944-12-06 1949-09-30 Pure Oil Co A method for sweetening hydrocarbon liquids containing mercaptans
CA471373A (en) * 1951-02-06 C. Bond Donald Removal of acidic sulfur compounds from hydrocarbon oils
US2552399A (en) * 1949-02-19 1951-05-08 Standard Oil Dev Co Treating petroleum distillates
CA475538A (en) * 1951-07-24 C. Bond Donald Sweetening of hydrocarbon liquids
US2638439A (en) * 1951-04-18 1953-05-12 Standard Oil Dev Co Treatment of petroleum distillates

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2015038A (en) * 1932-07-23 1935-09-17 Texas Co Process of sweetening petroleum hydrocarbons
US2346497A (en) * 1941-09-02 1944-04-11 Shell Dev Solutizer process
US2329616A (en) * 1942-04-27 1943-09-14 Air Reduction Treatment of hydrocarbon oils

Patent Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CA471373A (en) * 1951-02-06 C. Bond Donald Removal of acidic sulfur compounds from hydrocarbon oils
CA475538A (en) * 1951-07-24 C. Bond Donald Sweetening of hydrocarbon liquids
US2413945A (en) * 1944-03-09 1947-01-07 Standard Oil Co Treating petroleum distillates
US2427212A (en) * 1944-12-02 1947-09-09 Pure Oil Co Removal of peroxides from hydrocarbon oils
GB629914A (en) * 1944-12-06 1949-09-30 Pure Oil Co A method for sweetening hydrocarbon liquids containing mercaptans
US2474028A (en) * 1946-04-06 1949-06-21 Inventors Guild Recovery of phenol salts from aqueous solutions
US2552399A (en) * 1949-02-19 1951-05-08 Standard Oil Dev Co Treating petroleum distillates
US2638439A (en) * 1951-04-18 1953-05-12 Standard Oil Dev Co Treatment of petroleum distillates

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3063935A (en) * 1959-09-08 1962-11-13 Shell Oil Co Hydrocarbon sweetening process
US4428828A (en) 1981-01-02 1984-01-31 Chevron Research Company Upgrading hydrocarbonaceous oils with an aqueous liquid
US4481106A (en) * 1983-12-05 1984-11-06 Uop Inc. Hydrocarbon treating process

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FR1059231A (en) 1954-03-23
DE940005C (en) 1956-03-08
GB728586A (en) 1955-04-20

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