US2766181A - Naphtha sweetening with a phenylenediamine followed by alkali - Google Patents

Naphtha sweetening with a phenylenediamine followed by alkali Download PDF

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Publication number
US2766181A
US2766181A US376298A US37629853A US2766181A US 2766181 A US2766181 A US 2766181A US 376298 A US376298 A US 376298A US 37629853 A US37629853 A US 37629853A US 2766181 A US2766181 A US 2766181A
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United States
Prior art keywords
naphtha
naptha
aqueous caustic
extracted
inhibitor
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Expired - Lifetime
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US376298A
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English (en)
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Leonard V Sorg
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Standard Oil Co
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Standard Oil Co
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Priority to US376298A priority Critical patent/US2766181A/en
Priority to GB25786/54A priority patent/GB760543A/en
Priority to FR1115567D priority patent/FR1115567A/fr
Priority to DEST8807A priority patent/DE1031455B/de
Priority to BE532209D priority patent/BE532209A/xx
Application granted granted Critical
Publication of US2766181A publication Critical patent/US2766181A/en
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    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10G—CRACKING 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
    • C10G27/00—Refining of hydrocarbon oils in the absence of hydrogen, by oxidation
    • C10G27/04—Refining of hydrocarbon oils in the absence of hydrogen, by oxidation with oxygen or compounds generating oxygen

Definitions

  • This invention relates to the rening of cracked, sour naphthas. Particularly the invention relatesl to the sweeteni-ng of cracked, sou-r raw-naphthas, i. e., ⁇ those Which have not received any form of treatment subscquent to the production thereof by a cracking process.
  • the sweetening i. e., elimination of mercaptans, of cracked, sour naphthas is rendered dicult by the presence of reactive substituents, particularly gum-forming bodies.
  • Copper chloride sweetening of cracked', sour naphthas resul-ts in the production of Ia sweet naphtha that is quite unstable with respect to color; the addition of Vlarge amounts of metal deactivator is necessary to produce a stock of satisfactory stability.
  • Doctor sweetening is frequently unsatisfactory because the sweet naphtha contains corrosive sulfur.
  • ThisV process is now commonly known ⁇ as the inhibitor-sweetening method.
  • oxidation inhibitors of the phen-yiene diamine and alkylphenol types are added to the sour n-aphtha in the presence of aqueous caustic solution and free-oxygen.
  • Various modiiications of this technique have appeared in order -to increase the rate of sweetening which normally is very slow.
  • One of the better known methods comprises treating the sour, cracked naphtha with aqueous caustic solution to remove H28 and ⁇ some mercaptana the addition of the inhibitor and free-oxygen to the extracted naphtha, subsequently contacting this mixture with aqueous caustic solution and separating a naphtha substantially reduced in mercaptan content from aqueous caustic solution. if the naphtha is not substantially sweet at this point, normal- 1y, it will become sweet after being in storage for a day Vor two.
  • Another ,object of the invention is to sweeten cracked, sour naphthas by the inhibitor method.
  • Still another object is an inhibitor-sweetened naphtha which has .satisfactory gum stability.
  • a particular object is the inhibitor sweetening of catalytically cracked naphtha to produce a substantially sweet naphtha of satisfactory gum stability.
  • a substantially sweet product naphtha is separated from the aqueous caustic phase.
  • the contacting is carried out at a temperature between about and 100 F.
  • the raw naphtha charged to the process is al naphtha derived from a cracking process.
  • the cracking process may either be thermal cracking or thermal reforming or catalytic cracking.
  • the catalytic cracking process may be any one of the processes now conventionally used such vas fluid catalytic cracking, Houdry cracking, thermofor catalytic cracking, Houdry flow, etc.
  • the catalyst used in the catalytic cracking process may be clay-type or synthetic catalysts such as silica alumina and silica magnesia.
  • raw-naphtha is intended to include vnaphthas which 'have not received any chemical treatment which results in the removal of appreciable amounts of their ordinary constituents, particularly the removal of oxygenated compounds.
  • the raW-naphtha of this invention may be either the naphtha. as produced from the fractionation ofthe liquid product of the cracking of Ygas oil or heavy naphtha; or it maybe that naphtha which has been stored without any chemical treatmentv to remove HZS, cresois, etc.
  • I-t is preferred to ⁇ use asa feed to the process ⁇ raw-naphtha directly from the fractionator in order to avoid oxidation by atmospheric oxygen while in storage.
  • the sweetening agent used in the process of this vinvention is one which acts as an oxidation inhibitor as well as a catalyst for the conversion of mercaptans to disuldes.
  • This sweetening agent must be essentially insoluble in aqueous caustic solutions.
  • the sweetening agent .comprises a phenylene diamine type inhibitor and more particularly N-,NCdi-secondary-butyl-p-phenylene diamine.V However, it is understood that other phenylene diamine inhibitors may be.
  • the amount of phenylene diamine inhibitor utilized in the process will vary somewhat with the -type of raw- -na-phtha ycharged and also with the operating conditions. In general the phenylene diamine inhibitor usage will be at least about 2 pounds per 1000 barrels (42 gal.) of raw-naphtha. Amounts as much as 20 pounds or more may be used in some instances. Excessive usage has no harmful effect; however, it is uneconomic. It is preferred to use lbetween about 4 and '10 pounds of phenylene diamine inhibitor per 1000 barrels (42 gal.) of rawnaphtha.
  • the aqueous caustic solution may contain either sodium hydroxide or potassium hydroxide.
  • the aqueous caustic Isolution will contain about -10 Weight percent of caustic and the saturation amount, about' 50 weight percent. It is'preferred to use an aqueous caustic solution containing between about l5 and 30 weight percent of alkali metal hydroxide.
  • At least enough aqueous caustic solution must be Yused in the contacting of the raw-naphtha-inhibitor mixture to have present a distinct aqueous caustic phase. In some instances satisfactory results are obtainable by having only enough aqueous caustic solution present to form a haze in the mixture. More than this amount is usually desirable. Generally at least enough aqueous caustic solution is used to form a distinct, separate aqueous phase. Based on raw naphtha charged, the amount of aqueous caustic solution used may be between about and 100 volume percent.
  • the sweetening does not occur in the absence of freeoxygen. It has been found that the objects of the inven tion are attainable only if the naphtha-inhibitor mixture is contacted with aqueous caustic solution prior to or simultaneously with the addition of free-oxygen.
  • the free-oxygen may be derived either from the atmosphere by the use of air or by means of commercial cylinder oxygen.
  • the amount of free-oxygen needed is at least about the stoichiometric equivalent of mercaptan sulfur present in the naphtha, i. e., 1 mol of free-oxygen per 4 mols of mercaptan or 3 standard cubic feet of oxygen per pound of mercaptan sulfur. More than this amount is desirable and it is preferred to use between about 150 and 250% of the stoichiometric requirement.
  • the process of the invention may be utilized at temperatures as high as about 200 F. Temperatures as low as about 50 F. may be used when reaction rate is of little moment. It is preferred to operate at temperatures below about 110 F. as the naphtha sweetened at these temperatures has a more agreeable odor than does the naphtha sweetened at temperatures such as 150 F. or higher. It is preferred to carry out the sweetening step at a temperature between about 80 and 100 F.
  • the process may be carried out by contacting the naphtha-inhibitor mixture with aqueous caustic solution and substantially simultaneously with free-oxygen. The contacting is maintained for a time suicient to substantially sweeten the naphtha, The process may also be carried out by contacting the mixture with aqueous caustic solution, separating an aqueous caustic phase from a phase comprising naphtha and some occluded aqueous caustic solution and contacting this naphtha phase with free-oxygen until a substantially sweet naphtha is obtained.
  • the occluded aqueous caustic solution may be separated from the sweet naphtha by a settling operation or by passage through a coalescer such as a Salt drum or sand lter. Frequently the amount of occluded solution is so slight that normal storage will result in the separation of suicient aqueous solution to permit the naphtha to be used for commercial products without any special further dehazing treatment.
  • the preferred method of operation of the process comprises contacting the naphtha-inhibitor mixture with an aqueous NaOH solution containing between about and 30 weight percent NaOH in an amount sufficient to form a separate aqueous caustic layer, separating the extracted naphtha from an aqueous caustic layer, adding the desired amount of free-oxygen to the extracted naph tha, contacting the extracted naphtha-oxygen mixture with aqueous NaOH solution in about the same concern tration and quantity as in the first contacting step and separating a sweet product naphtha from aqueous caustic solution.
  • the process is carried out at a temperature between about 80 and 100 F.
  • the cracked, sour raw-naphtha feed in all cases was a stabilized heavy naphtha boiling between about 130 and 400 F. which had been derived from the fluid catalytic cracking, using a synthetic catalyst, of a gas oil. Some tests were made utilizing a mixture of the catalytically cracked SHN and a gasoline base stock which consisted of a mixture of virgin and thermally cracked naphthas.
  • the tests were carried out in a small continuous unit.
  • This unit consisted of two l-gallon vessels connected in series; each vessel was preceded by an orifice-type mixer. These vessels operated as settlers and the lower aqueous phase was withdrawn from the settler and circulated to the naphtha line ahead of the mixer by means of a pump.
  • the temperature maintained in the system was con trolled by means of steam heaters in the aqueous solution circulating lines.
  • each vessel was charged with 2.5 liters of aqueous caustic solution con- 0 taining 2l weight percent of NaOH.
  • the unit was so arranged that air could be injected into the naphtha line between the irst vessel and the second mixer.
  • the amount of air injected was regulated by means of a rotameter.
  • the catalytically cracked SHN was held in SO-gallon drums which had been swept out with nitrogen.
  • the catalytic SHN was obtained directly from the fractionating tower prior to exposure to the atmosphere.
  • phenylene diamine inhibitor used was N,Ndisecondarybutylp-phenylene diamine.
  • the raw-naphtha-inhibitor mixture is passed from line 18 into mixer 19.
  • Aqueous sodium hydroxide solution from line 21 is introduced into mixer 19.
  • Mixer 19 may be either a knothole-type mixer or a mechanically stirred mixer. In mixer 19 the aqueous caustic solution and the mixture are intimately contacted. The contents of mixer 19 are passed by way of line 22 into settler 23.
  • Settler 23 may be any form of vessel for permitting :the gravitytseparationrdf:twoaimmiscible phases. ⁇ Azlower Vlayer V-of .aqueous :caustic solution is withdrawn. ⁇ 'trom settlerL 2'31by way of line 2L4;
  • the naphtha from line 14 contains hydrogen sulfide, cresols and mercaptans. These materials react with the sodium hydroxide and decrease the effective strength of the aqueous caustic solution. Periodically when the aqueous caustic solution has reached a concentration of below about l0 weight percent free sodium hydroxide, a portion of the aqueous caustic solution from line 24 is withdrawn from the system by way of valved line 29.
  • Makeup aqueous caustic solution is introduced into the system from source 31 by way of valved lines 32 and 26.
  • the aqueous caustic solution contains 25 weight percent of sodium hydroxide.
  • the extracted naphtha is passed from settler 23 by way of line 34.
  • Commercial grade cylinder oxygen from source 36 is introduced by way of line 37 into line 34.
  • the naphtha-oxygen stream is passed by way of line 38 into mixer 39.
  • Aqueous caustic solution from line 41 is introduced into mixer 39.
  • Mixer 39 is similar in construction to mixer 19.
  • the contents of mixer 39 are passed by way of line 42 into settler 43.
  • Settler 43 is similar in construction to settler 23.
  • the lower aqueous caustic layer is withdrawn from settler 43 by way of line 46 and is recycled to the process by Way of valved line 47, heat exchanger 48 and line 41.
  • heat exchanger 48 the circulating aqueous caustic solution is raised to a temperature such that the contents of mixer 39 are maintained at a temperature of about 90 F.
  • aqueous caustic solution withdrawn from settler 43 eventually becomes contaminated with reaction products. Periodically a portion of the circulating stream may be withdrawn from the system by way of line 46 and valved line 51. This contaminated aqueous caustic solution contains a considerable amount of free-caustic. Therefore a portion of the aqueous caustic solution may be passed by way of line 46 and valved line 52 to line 24 for use in the rst aqueous caustic treating zone.
  • Fresh aqueous caustic solution from source 56 is introduced by way of line 57 into line 47.
  • This aqueous caustic solution contains 25% of sodium hydroxide.
  • Suicient makeup solution is added to maintain in the system about 20 volume percent of aqueous solution based on naphtha introduced from line 38.
  • a sweet product naphtha is withdrawn from settler 43 by way of line 61 and is passed to storage not shown.
  • a process of sweetening a cracked, sour rawnaphtha which process comprises (l) adding to said raw naphtha, substantially immediately after said raw naphthas production from the liquid product of the prior cracking operation, a phenylene diamine inhibitor, in an amount between about 4 and 10 pounds per 1000 barrels of said naphtha, (2) contacting said mixture, at a temperature between about and 100 F.

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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)
  • Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
US376298A 1953-08-25 1953-08-25 Naphtha sweetening with a phenylenediamine followed by alkali Expired - Lifetime US2766181A (en)

Priority Applications (5)

Application Number Priority Date Filing Date Title
US376298A US2766181A (en) 1953-08-25 1953-08-25 Naphtha sweetening with a phenylenediamine followed by alkali
GB25786/54A GB760543A (en) 1953-08-25 1954-09-06 Improvements in or relating to naphtha sweetening process
FR1115567D FR1115567A (fr) 1953-08-25 1954-09-28 Perfectionnements à un procédé d'adoucissement du naphta
DEST8807A DE1031455B (de) 1953-08-25 1954-09-29 Suessen von Benzinen
BE532209D BE532209A (xx) 1953-08-25 1954-09-30

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US376298A US2766181A (en) 1953-08-25 1953-08-25 Naphtha sweetening with a phenylenediamine followed by alkali

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US (1) US2766181A (xx)
BE (1) BE532209A (xx)
DE (1) DE1031455B (xx)
FR (1) FR1115567A (xx)
GB (1) GB760543A (xx)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2960461A (en) * 1958-12-12 1960-11-15 American Oil Co Inhibitor sweetening of olefinic polymer

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3371031A (en) * 1967-03-02 1968-02-27 Universal Oil Prod Co Oxidation of mercapto compounds

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2547181A (en) * 1949-01-12 1951-04-03 Standard Oil Co Distillate sweetening process
US2552399A (en) * 1949-02-19 1951-05-08 Standard Oil Dev Co Treating petroleum distillates
US2616833A (en) * 1951-03-01 1952-11-04 Universal Oil Prod Co Treatment of hydrocarbon distillates
US2634231A (en) * 1951-04-16 1953-04-07 Universal Oil Prod Co Sweetening of sour hydrocarbon distillates

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2547181A (en) * 1949-01-12 1951-04-03 Standard Oil Co Distillate sweetening process
US2552399A (en) * 1949-02-19 1951-05-08 Standard Oil Dev Co Treating petroleum distillates
US2616833A (en) * 1951-03-01 1952-11-04 Universal Oil Prod Co Treatment of hydrocarbon distillates
US2634231A (en) * 1951-04-16 1953-04-07 Universal Oil Prod Co Sweetening of sour hydrocarbon distillates

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2960461A (en) * 1958-12-12 1960-11-15 American Oil Co Inhibitor sweetening of olefinic polymer

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Publication number Publication date
FR1115567A (fr) 1956-04-26
BE532209A (xx) 1958-01-31
GB760543A (en) 1956-10-31
DE1031455B (de) 1958-06-04

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