Classifications

• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07D—HETEROCYCLIC COMPOUNDS
  • C07D307/00—Heterocyclic compounds containing five-membered rings having one oxygen atom as the only ring hetero atom
  • C07D307/77—Heterocyclic compounds containing five-membered rings having one oxygen atom as the only ring hetero atom ortho- or peri-condensed with carbocyclic rings or ring systems
  • C07D307/91—Dibenzofurans; Hydrogenated dibenzofurans
• • 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
• • 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
  • C10G27/12—Refining of hydrocarbon oils in the absence of hydrogen, by oxidation with oxygen or compounds generating oxygen with oxygen-generating compounds, e.g. per-compounds, chromic acid, chromates
• • 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
  • C10G53/00—Treatment of hydrocarbon oils, in the absence of hydrogen, by two or more refining processes
  • C10G53/02—Treatment of hydrocarbon oils, in the absence of hydrogen, by two or more refining processes plural serial stages only
  • C10G53/14—Treatment of hydrocarbon oils, in the absence of hydrogen, by two or more refining processes plural serial stages only including at least one oxidation step

Definitions

• This invention relates to processes for the desulfurization of heavy petroleum hydrocarbon fractions, and particularly to processes for desulfurization residua.
• residua and gas oils contain significant quantities of organometallic compounds such as vanadium, nickel, and iron porphyrins, which are poisons for desulfurization catalysts, and because of the high tendency for coke formation of the high molecular weight hydrocarbons and asphaltenes found in residua and gas oil, severe catalyst deactivation is unavoidable.
• organometallic compounds such as vanadium, nickel, and iron porphyrins
• Heavy petroleum hydrocarbon fractions and particularly petroleum residua, are desulfurized according to the present invention by (1) contacting the hydrocarbon fraction with an oxidizing agent in a aqueous acidic medium, thereby oxidizing bivalent sulfur compounds such as thiophene to sulfur oxygen compounds such as sulfoxides and sulfones, (2) contacting the oxidized hydrocarbon fraction containing the sulfur-oxygen compounds with a molten alkali metal hydroxide, thereby rupturing the carbon-sulfur bond and forming water soluble sulfur compounds, and (3) recovering a hydrocarbon fraction of reduced sulfur content.
• an oxidizing agent in a aqueous acidic medium
• bivalent sulfur compounds such as thiophene
• sulfur oxygen compounds such as sulfoxides and sulfones
• This invention is useful in the treatment of heavy petroleum derived hydrocarbon fractions containing bivalent sulfur compounds, and especially thiophenes.
• the heavy petroleum fractions treated according to this invention include higher boiling range petroleum fractions such as topped crudes, gas oils, and residua. These fractions may be characterized generally as petroleum hydrocarbon fractions over 30% of which boil at a temperature above 900 F.
• This invention is particularly applicable to the treatment of residua of high sulfur crudes.
• a residuum is the heavy fraction which remains in crude oil after the lighter fractions, including naphtha and gas oil, have been removed.
• the atmospheric residuum of Safaniya crude oil is representative of the high sulfur materials which may be benefited by this invention.
• a typical analysis of Safaniya atmospheric residuum is as follows:
• the first step in the instant process is to oxidize the thiophene content to the sulfoxide or sulfone state. This is done by contacting the heavy hydrocarbon fraction with a suitable oxidizing agent. Before proceeding with this step, it is desirable to dissolve materials of high viscosity such as residua in an inert hydrocarbon medium such as benzene.
• -It is desirable to dissolve materials of high viscosity such as residua in an inert hydrocarbon medium such as benzene before treating according to this invention.
• the oxidizing agent utilized for this invention may be any of the several Well-known oxidizing agents.
• the preferred agent is hydrogen peroxide in a liquid acidic medium, e.g., acetic acid.
• a variety of reagents may be substituted for hydrogen peroxide. These include the alkali metal periodates, perchlorates, chromates, and permanganates; metal oxides such as manganese dioxide and chromic oxide; perchloric and hypochlorous acids; metal peroxides, especially barium peroxide; peracids such as performic, peracetic, pertrichloroacetic, perbenzoic, and perphthalic acids; and organic peroxides and hydroperoxides such as tert-butyl hydroperoxide.
• the acidic medium which appears to act as a catalyst, may be a water soluble organic carboxylic acid such as formic acid, acetic acid, chloroacetic acid, dichloroacetic acid, or trichloroacetic acid; a sulfonic acid such as benzenesulfonic acid or carbobenzoxysulfonic acid; an oxymineral acid such as sulfuric, nitric, or chloric acid; or mixtures of two or more of the above acids.
• the acidic medium is an aqueous solution of the acid, although the presence of water is not essential if the anhydrous acid is a liquid.
• a particularly effective catalyst is acetic acid.
• the acid concentration is generally from about 10% to about 100%- by volume.
• the oxidation reaction of this invention may be carried out by mixing the hydrocarbon fraction, preferably dissolved in an inert hydrocarbon solvent such as benzene, with the aqueous acidic solution.
• the reaction mixture is agitated vigorously by stirring, for example, throughout the reaction in order to assure a good contact between the hydrocarbon and the aqueous phase.
• Hydrogen peroxide or other oxidizing agents is added to the reaction medium incrementally throughout the reaction.
• the entire amount of oxidizing agent may be charged to the aqueous medium prior to admixture with the hydrocarbon, but best results are obtained when the oxidizing agent is added incrementally as the reaction progresses.
• the reaction may be carried out at either subatmospheric, atmospheric, or superatm-ospheric pressures, and at elevated temperatures ranging from about to about 300 F.
• the results obtained at atmospheric pressure are just as good as those obtained at either subatmospheric or superatmo-spheric pressure, and hence atmospheric pressure is preferred.
• Excellent results may be obtained when operating at the reflux temperature of the hydrocarbon diluents; in the case of benzene, this is about 167 F.
• the oxidation reaction may be carried out over periods of time ranging from about 10 minutes up to about 4 hours or more. Complete oxidation can generally be obtained in periods ranging from about 30 minutes to about 2 hours.
• the oxidation conditions utilized in the present invention oxidize the bivalent sulfur compounds to the sulfone state.
• a part of the bivalent sulfur may be oxidized only to the sulfoxide state.
• sulfone formation is preferred because the sulfones are more easily cleaned than sulfox ides in the second step of the reaction according to this invention.
• the aqueous and hydrocarbon phases are separated, and the oxidized hydrocarbon fraction (i.e., the hydrocarbon fraction containing an oxidized sulfur compound such as a sulfone or sulfoxide) is then treated according to the second step of the process of this invention.
• the oxidized hydrocarbon fraction i.e., the hydrocarbon fraction containing an oxidized sulfur compound such as a sulfone or sulfoxide
• Benzene or other diluent used in the first step of the reaction may be distilled off prior to the second step; this is a preferred procedure, since the hydrocarbon diluent would be instantly volatilized at the reaction temperatures prevailing in the second step.
• the hydrocarbon fraction containing the oxidized sulfur compound is contacted with an alkali metal hydroxide in the molten state.
• the preferred base is sodium hydroxide, but equally successful results have been achieved with potassium hydroxide. Excellent results have been obtained at temperatures in the range of about 572 to about 752 F. (about 300 to about 400 C.); generally,
• the reaction may be conducted at temperatures ranging from about 482 to about 842 F. (about 250 to about 450 C.).
• the reaction is most advantageously carried out at pressures of about to about 100 p.s.i.g., although higher or lower pressures may be used.
• the reaction is carried out in a corrosion resistant autoclave, either glass lined or made of a corrosion resistant alloy such as Inconel, for example, under autogenous pressure at desired temperature.
• the reaction requires at least moles of alkali metal hydroxide for every mole of sulfone to be treated.
• the preferred amounts of metal hydroxide will be from about 0.5 to about 1.5 parts by weight of alkali metal hydroxide on the anhydrous basis for each part by weight of residuum. (This corresponds to about to 30 moles of NaOH per mole of sulfur, assuming the residuum contains 4.2% by weight S.) These ratios have been found suitable in treating a high sulfur residuum such as the atmospheric residuum from Safaniya crude; it will be understood that the amount of alkali metal hydroxide will be proportionately less when the sulfur content of the hydrocarbon fraction being treated is lower.
• the reaction mechanism for the cleavage of sulfones by alkali metal hydroxides is not clear cut. A slight amount of the hydrocarbon residuum may enter the reaction.
• the principal reaction products are a desulfurized hydrocarbon fraction having significantly lower sulfur content than the original hydrocarbon fraction, and various inorganic sulfur and carbon compounds such as sulfides, sulfites, sulfates, thiosulfates, and carbonates.
• the use of potassium hydroxide as the base favors the formation of carbonate to a much greater extent than does the use of sodium hydroxide.
• Sulfide is the preponderant sulfur-bearing ion in the reaction product mixture. It will be noted that the greater part of the sulfur present in the hydrocarbon fraction after the first stage is transformed in the second step into water soluble inorganic sulfur compounds.
• Alkali metal hydroxides are the only bases which have been found to be effective according to the present invention. Other bases such as calcium hydroxide, sodium carbonate, potassium carbonate, and cupric oxide are not effective.
• the reaction mixture Upon completion of the alkali metal hydroxide treatment, the reaction mixture is cooled and water is added in order to dissolve the inorganic reaction products.
• the sulfur compound, as well as excess unreacted alkali go into the aqueous phase.
• the aqueous phase can be separated from the hydrocarbon phase by allowing the reaction mixture to settle.
• the heavy hydrocarbon fraction having considerably reduced sulfur content as compared to the initial or untreated heavy hydrocarbon fraction is recovered. Generally, sulfur removals of about 75 to 90% can be obtained according to this invention.
• Examples 1 to 3 illustrate desulfurization of an atmospheric residuum of a high sulfur crude oil, showing the effect of varying the oxidizing agent to feed ratio and of using different reaction media in the oxidation step, and the effect of varying the caustic to hydrocarbon ratio in the desulfurization step.
• Example 1 This example describes the desulfurization of a high sulfur residuum obtained by atmospheric distillation of Safaniya crude oil.
• the residuum was desulfurized in a two-step process comprising oxidation followed by caustic treatment.
• the residuum contained 4.2% by weight S, mostly in the form of thiophenes.
• the desulfurized residuum was obtained by distilling off the benzene diluent. The sulfur content of each residuum sample was determined. The desulfurization procedure was also carried out on two 50 ml. aliquots of unoxidized residuum.
• Example 2 This example illustrates desulfurization of a high sulfur residuum in a process comprising oxidation with hydrogen peroxide followed by caustic desulfurization, using sulfuric acid as a catalyst in the oxidation step.
• This example illustrates the effects of the base-toresiduum ratio and of temperatures on desulfurization.
• the behavior of a sulfur-containing residuum can be
• the oxidation products of this example may be reacted predicted in large measure in laboratory tests using a rewith caustic alkali according to any of the procedures in fined heavy hydrocarbon oil to which a specific sulfur Examples 1 to 4 in order to obtain a hydrocarbon fraccompound has been added.
• Examples 4 to 9 illustrat tion (in this case white oil) of reduced sulfur content. such tests, using a white oil to which dibenzothiophenc
• this invention represents a significant improvement in the oxidation art.
• the addition of small quantities of sulfuric acid will greatly reduce the amount of acetic acid needed to maintain a high reaction rate and therefore permit the use of large amounts of water. Because acetic acid is more soluble in water than in oils, good recovery of the acetic acid will be possible. Furthermore, the use of dilute aqueous media reduces the possibility of emulsion formation, which would complicate acid recovery in a commercial process.
• halogenated acetic acids such as mono-, di-, and tri-chloroacetic acids
• sulfuric acid will not be needed to speed up the reaction since it proceeds satisfactorily.
• the haloacetic acids have very much higher acid strengths than acetic acid itself.
• the haloacetic acids are stronger acids and have higher polarities, they are much less oil soluble than acetic acid and would be more readily recovered. The advantages of using haloacetic acids are illustrated in the example below.
• Example 6 These experiments were conducted in the same manner as those discussed in the previous example except that the indicated haloacetic acid was used in place of the sulfuricacetic acid mixtures.
• 5.14 g. of dibenzothiophene and cc. of n-hexadecane (chromatographic standard) were dissolved in 100 cc. of white oil and heated to 212 F. This oil was then brought into reaction with oxidation mixtures made up of 0.435 mole of the acid catalyst indicated below in 75 cc. of water to which 16.6 cc. of 30 weight percent H 0 was added. Again, aliquot samples of the oil were withdrawn and analyzed by gas chromatography to determine the extent of dibenzothiophene disappearance. The reaction product was found to be dibenzothiophene sulfone.
• Examples 7 and 8 show that barium peroxide in an acidic reaction medium can be used instead of hydrogen peroxide as the oxidizing agent.
• Example 7 In this example barium peroxide in an aqueous acetic acid reaction medium was utilized as the oxidizing agent for dibenzothiophene dissolved in a hydrocarbon oil. About 5.14 g. of dibenzothiophene (DBT) and 5 cc. of small n-hexadecane were dissolved in 100 cc. of heavy white oil. A mixture of 100 cc. of glacial acetic acid into 25 cc. of water was utilized as the reaction medium. The solution of dibenzothiophene and n-hexadecane in the white oil was added to the reaction medium. The resulting mixture was heated to 212 F.
• DBT dibenzothiophene
• n-hexadecane small n-hexadecane
• Example 8 TABLE VII Total, Mole Percent Time, Grns, BaOz BaOg/Mole DBT Conv. mm. Added DBT by GO Example 8 This example shows the effect of varying the ratio of acetic acid to water, and the effect of incremental addition of barium peroxide versus addition of the entire amount at the beginning of the reaction period.
• the reaction conditions were the same as in Example 7, except that the amounts of acetic acid in water present were varied as indicated in Table VIII.
• barium peroxide when used in conjunction with water and acetic acid, produces an excellent conversion of dibenzothiophene.
• the preferred rate of addition of the barium peroxide i.e., about 1 to 2 moles of BaOg/mole S/hr., serves to enhance greatly the performance of the instant invention.
• n-hexadecane in 100 cc. of white oil in a 300 cc. autoclave. Then 22.2 g. of 85% by weight barium peroxide was added, and the reaction mixture was heated to 212 F. at autogenous pressure with stirring. No reaction took place. Increasing the temperature up to 572 F. still did not produce any oxidation of dibenzothiophene to the sulfone state even after 21 hours.
• Comparison Run C The procedure of Comparison Run B was followed except that the water was omitted from the reaction mixture. As in Comparison Run B, no reaction was observed.
• Sodium periodate catalyzed by aqueous acetic acid is also an effective oxidizing agent for dibenzothiophene, as shown in Example 9'.
• Example 9 This example shows the effect of various conditions, i.e., temperature, acid concentration, and mole ratio of sodium periodate to sulfur compound, in oxidizing dibenzothiophene in white oil.
• a series of runs was made in which 0.028 g. moles (about 5.14 g.) of dibenzothiophene was added to a mixture of 100 cc. of white oil and cc. of hexadecane in a reaction flask.
• Sodium periodate in 100 cc. of aqueous acetic acid was added to this mixture, and the resulting mixture was heated with stirring. Reaction temperature and time, and the amounts of acetic acid, water, and sodium periodate used to make up the aqueous phase, as well as the results obtained, are shown in Table IX below.
• a process according to claim 1 including the steps of adding water to the reaction mixture obtained on contacting said hydrocarbon fraction with said alkali metal hydroxide, thereby dissolving water soluble sulfur compounds and unreacted alkali metal hydroxide in the aqueous phase, and separating said aqueous phase from said hydrocarbon fraction.
• the results of Runs 6, 7, 8 and 11 show the advantage of carrying the reaction out at 212 F.
• the results of Runs 9, l0 and 11 show that increased acetic acid concentration also has a beneficial effect on the extent of conversion. Extremely good results can be obtained at 212 F. using 4 moles of NaIO per mole of S compound in aqueous solutions containing 25 to 75% by volume of acetic acid.
• a process for reducing the sulfur content of a heavy petroleum hydrocarbon fraction, having an initial boiling point above about 600 F. and which contains bivalent sulfur in the form of thiophenes which comprises:
• a process for treating a heavy petroleum hydrocarbon fraction in order to oxidize bivalent sulfur therein which comprises contacting the hydrocarbon fraction with an aqueous solution of an organic carboxylic acid and a peroxide selected from the group consisting of the alkali metal and alkaline earth metal peroxides under reaction conditions for oxidizing said bivalent sulfur.
• a process for treating a heavy hydrocarbon fraction containing bivalent sulfur in order to oxidize said sulfur which comprises contacting said hydrocarbon fraction at reaction conditions with an aqueous solution of an organic carboxylic acid and a Water-soluble periodate.
• a process for reducing the sulfur content of a heavy petroleum hydrocarbon fraction having an initial boiling point above about 600 F. and which contains bivalent sulfur in the form of thiophenes which comprises:

Landscapes

• Chemical & Material Sciences (AREA)
• Oil, Petroleum & Natural Gas (AREA)
• Organic Chemistry (AREA)
• Engineering & Computer Science (AREA)
• Chemical Kinetics & Catalysis (AREA)
• General Chemical & Material Sciences (AREA)
• Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)

Applications Claiming Priority (2)

Publications (1)

Family

ID=27030259

Family Applications (1)

Country Status (2)

Cited By (49)

Citations (6)

• 1966
  • 1966-02-22 NL NL6602260A patent/NL6602260A/xx unknown
• 1968
  • 1968-06-04 US US734228A patent/US3505210A/en not_active Expired - Lifetime

Patent Citations (6)

Also Published As

Similar Documents