Classifications

• • 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

• the present invention relates to a process for oxidising sulphur derivatives useful in the removal of unwanted sulphur from sulphur containing hydrocarbon oils.
• Heavy oils occur widely throughout the world and contain significant quantities of chemically bound sulphur.
• the presence of sulphur poses problems in that it poisons many catalytic systems employed in processes to convert heavy hydrocarbon fractions to lighter oils and gasolines.
• the combustion of such sulphur containing oils leads to the release of undesirable sulphur containing species known to add to atmospheric pollution.
• US 3551328 discloses a process for the desulphurisation of heavy hydrocarbon fractions by the oxidation of the sulphur impurities by contacting the hydrocarbon fraction with an oxidant in the presence of an oxidation promoting catalyst and further treatment with a lower paraffinic hydrocarbon solvent to separate the oxidised sulphur compounds from the hydrocarbon fraction.
• US 3565793 discloses a process for the desulphurisation of hydrocarbon materials by the oxidation of the sulphur impurities and subsequent removal of the oxidised sulphur compound by thermal treatment or addition of a base.
• US 3595778 discloses a desulphurisation process comprising the oxidation of the sulphur containing compounds by ozone and a vanadium catalyst followed by thermal or base treatment.
• US 3847800 discloses a process wherein sulphur and nitrogen components are removed from petroleum oils comprising reacting the petroleum oils with a gas which includes one or more oxides of nitrogen and mixing the oxidised oil with a solvent immiscible with the oil.
• the present invention comprises a process for desulphurising hydrocarbon oils comprising the steps of (1) treating a sulphur containing hydrocarbon oil with a catalyst consisting essentially of an aqueous acidic or neutral solution of a molybdenum, tungsten or vanadium heteropolyanion and an oxidant under conditions such that the sulphur is oxidised and (2) separating the oxidised sulphur from the treated hydrocarbon oil.
• the present invention has the advantage that operating conditions are mild and selectivity to sulphur oxidation is high without significant amounts of unwanted side reactions.
• the catalyst used to effect oxidation of the sulphur is a molybdenum, tungsten or vanadium heteropolyanion. Such species are described in detail in 'Heteropoly and Isopoly Oxo-metalates' by Pope et al , Springer-Verlag, New York 1983.
• a preferred class of heteropolyanions for use in the process of the present invention are those derivable by ionisation of heteropolyacids having the general formula H e (X k M n O y ) where X is phosphorus, antimony, silicon, germanium or boron and M is molybdenum, tungsten or vanadium. It is also preferred that k is from 1 to 5, n is from 5 to 40 and y is from 18 to 62. It will be appreciated that the value of e will equal the valence of the anion (X k M n O y ) e- which in turn will depend upon the value of the other variables.
• a particularly preferred class of heteropolyanions are those having the general formula (XM12O40)3 ⁇ . Of these, the most preferred are those of formula (PM12O40)3 ⁇ where M is either molybdenum or tungsten.
• Such species can be conveniently prepared in situ under the reaction conditions from either (1) the corresponding heteropolyacid H3PM12O40 or alkali metal or ammonium salts thereof or (2) a combination of acid, phosphate and tungstate, molybdate or vanadate salts or acids.
• the volume of the aqueous catalyst phase used should be in the range 0.1 to 10 times the volume of the oil.
• the amount of catalyst should range from 0.0001 to 0.1 moles for every litre of water.
• phase transfer catalyst Whilst the oxidation can be carried out by emulsifying the oil and aqueous catalyst phase, it is preferred that oxidation is carried out in the presence of a phase transfer catalyst.
• Suitable phase transfer catalysts are pyridinium, quaternary ammonium or phosphonium salts, for example tricaprylylmethylammonium chloride and tetraoctylammonium bromide.
• the oxidants which may be used in the oxidation step include hydrogen peroxide, alkyl hydroperoxides, eg tertiarybutylhydro peroxide, oxygen and air.
• the preferred oxidant is hydrogen peroxide.
• the amount of oxidant required will largely be dependant on the amount of sulphur present in the oil.
• a mole ratio of oxidant to sulphur from 0.5 to 20 is preferred.
• pressures of up to 5MPa and 25MPa respectively are suitable.
• the oxidised sulphur is separated from the treated oil.
• Such separation can be effected in a number of ways including solvent extraction, adsorption, pyrolysis to form sulphur monoxide and/or sulphur dioxide, acid hydrolysis and precipitation.
• One preferred method however is to contact the treated hydrocarbon oil with an immiscible solvent.
• Preferred solvents include C1 to C4 alcohol and C1 to C4 alcohol/water mixtures, examples of which are methanol or methanol/water.
• the amount of immiscible solvent used is typically in the range 0.5 to 10 times the volume of hydrocarbon oil being treated.
• Another preferred method is adsorption of the sulphur on an active material such as alumina silica charcoal or the like. This can be achieved by, for example, passing the hydrocarbon oil through a bed or column of the material onto which absorption occurs.
• H2O2 (16.8 mmol; 19% by volume) was added to diesel (20.0g, 0.253% wt S) containing tricaprylylammonium chloride (0.25 mmol).
• aqueous solution of phosphomolybdic acid 0.022 mmol.
• the reaction mixture was heated to 60°C for 2.5h. A small amount of a dark brown oil was observed to precipitate from solution whilst the diesel became dark brown-orange in colour.
• the diesel phase was extracted with methanol (2 x 25 cm3 portions) the latter assuming an orange/brown colouration.
• the % sulphur content of the extracted diesel (determined by XRF) was found to be 0.097%.
• H2O2 (16.8 mmol; 19% by volume) was added to diesel (20.0g, 0.253% wt S) containing tricaprylylammonium chloride (0.25 mmol).
• diesel (20.0g, 0.253% wt S) containing tricaprylylammonium chloride (0.25 mmol).
• 7.5 cm3 of an aqueous solution of phosphotungstic acid (0.01 mmol).
• the reaction mixture was heated to 60°C for 2.5h.
• the diesel was extracted with methanol as described in Example 1.
• the %S content of the extracted diesel was found to be 0.085 % wt.
• H2O2 (11.96 mmol, 19% by volume) was added to a diesel (20.1 g, 0.253 % wt S) containing tricaprylylammonium chloride (0.124 mmol).
• methanol (10.15 g) and phosphomolybdic acid H3PMO12O40 (0.022 mmol).
• the reaction mixture was heated to 60°C for 2.5h.
• the methanol phase assumed a dark green/brown colouration but on cooling turned dark orange-brown in colour.
• the diesel was separated and then extracted with a further 25 cm3 of methanol.
• the % S content of the extracted diesel was found to be 0.076 % wt.
• H2O2 (6.38 mmol, 19% by volume) was added to diesel (9.9g) containing tricaprylylammonium chloride (0.124 mmol). To this was added 10.0g of an aqueous solution of phosphotungstic acid (0.03 mmol). The reaction mixture was heated to 60°C for 1.5h. The aqueous phase was separated and this together with H2O2 (14.25 mmol, 19% by volume) was added to diesel (20.1g, 0.253% wt S) containing aliquat 336 (0.124 mmol). The reaction mixture was heated to 60°C for 2 h. A brown oil precipitated from solution and the diesel phase was extracted with methanol as described in Example 1. The % S content of the extracted diesel was 0.085% wt.
• a two-litre glass reactor was charged with 776.8g of a diesel oil (UK winter grade from BP's Grangemouth Refinery, no ignition improver, consisting essentially of straight run non-hydrotreated gas oil, 0.253 wt. % sulphur), phosphotungstic acid (2.5g in 15g water), 'Aliquat 336' (tri-n-octylmethylammonium chloride, 4.15g), and a solution of H2O2 (49.8g 100%) in 388.9g H2O.
• the contents were heated to 60°C and stirred at that temperature for 4 hours, then cooled to 20°C.
• the bulk diesel phase was separated from the aqueous phase and a small pecipitate of a dark brown oil (5g). XRF analysis showed the bulk phase and the precipitate to contain 0.255 and 1.87 wt % sulphur respectively.
• a 187.8g sample of diesel oxidised as described in Example 6 was charged to a 600 cm3 stainless steel Baskerville autoclave which was then capped, leak tested with N2 at 45 bar and then vented to 0 bar gauge and sealed. The contents were stirred at 250 rpm, heated to 400°C over 11 ⁇ 2 h and kept at 400-410°C for one hour. After slow cooling overnight to ambient temperature, the final pressure was 1.0 bar gauge. Nitrogen gas was added to 5 bar gauge and the gases then released through a NaOH (aq) scrubber. The vessel was pressured to 45 bar with N2 and then slowly vented. On opening the vessel a striging odour was apparent. The liquors were collected (182.3g) leaving a small amount of a carbonaceous residue and degassed for 15 mins with a stream of N2. Analysis by XRF showed the presence of 0.177 wt % sulphur.

Landscapes

• 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)
• Catalysts (AREA)
• Production Of Liquid Hydrocarbon Mixture For Refining Petroleum (AREA)

Applications Claiming Priority (2)

Publications (1)

Family

ID=10684350

Family Applications (1)

Country Status (3)

Cited By (19)

Citations (5)

• 1990
  • 1990-10-25 GB GB909023257A patent/GB9023257D0/en active Pending
• 1991
  • 1991-10-18 EP EP91309649A patent/EP0482841A1/fr not_active Ceased
  • 1991-10-23 CA CA 2054070 patent/CA2054070A1/fr not_active Abandoned

Patent Citations (5)

Also Published As

Similar Documents

Legal Events