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
  • 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

Definitions

• the present invention relates to a process for desulfurization of a mixture of hydrocarbons containing sulfur compounds, comprising at least one oxidation step, in which hydrogen peroxide, acid is used as the oxidant.
• acetic acid catalyst to oxidize sulfur compounds.
• RSR' represents an aliphatic or aromatic sulfur compound
• the present invention aims to avoid the aforementioned drawbacks and to provide a new process for removing sulfur from hydrocarbon mixtures which makes it possible to significantly reduce the sulfur content.
• the invention therefore relates to a process for desulfurization of a mixture of hydrocarbons containing sulfur compounds, comprising an oxidation step using hydrogen peroxide, acetic acid and an acid catalyst in order to oxidize sulfur compounds, in which the acid catalyst contains an acid solid chosen from cation exchange resins having a pKa of less than or equal to 4, from solids based on silicon oxide additionally containing a trivalent metal, and from particles of inorganic solid on which acid organic groups are grafted so that the particles thus grafted have a pKa less than or equal to 4.
• the acid catalyst contains an acid solid chosen from cation exchange resins having a pKa of less than or equal to 4, from solids based on silicon oxide additionally containing a trivalent metal, and from particles of inorganic solid on which acid organic groups are grafted so that the particles thus grafted have a pKa less than or equal to 4.
• pKa is meant to denote - log Ka where Ka is the dissociation constant of the acid in an aqueous medium at 25 ° C.
• the acid catalyst is necessary to accelerate the formation of peracetic acid from hydrogen peroxide and acetic acid by the reaction [1]
• the peracetic acid thus formed is the substance which oxidizes sulfur compounds, in particular to corresponding sulfones, according to the reaction [2 ]
• At least two phases can be distinguished: an organic phase consisting essentially of the mixture of hydrocarbons and which may possibly contain part of the acetic acid and part of the peracetic acid, and a phase aqueous containing essentially water, hydrogen peroxide, part of acetic acid and part of peracetic acid.
• the solid catalyst can be in contact with the aqueous and organic phases in a three-phase medium, the third phase being solid and consisting of the solid catalyst.
• the catalyst can for example be used in suspension in the reaction medium or in the form of a fixed bed. In both cases, the fact of using a solid has the advantage that the catalyst can be easily separated from the reaction medium and in particular from the organic phase, for example by filtration when the catalyst is suspended. Therefore, contamination of the organic phase by the catalyst is avoided.
• the catalyst in contact with the aqueous phase only, in a separate tank, for example in the form of a suspension, a fixed bed or a fluid bed.
• This second configuration has the additional advantage of avoiding secondary reactions between the catalyst and the organic phase, and in particular the acid-base reactions mentioned above.
• mixture of hydrocarbons is meant any product containing predominantly combustible hydrocarbons such as paraffins, olefins, naphthenic compounds and aromatic compounds. It may be crude oil or a petroleum derivative obtained by any known refining treatment.
• the mixture of hydrocarbons can be chosen from motor fuels such as petrol or diesel, and from domestic fuels such as heating oil.
• sulfur compounds means all the compounds present in the mixture of hydrocarbons which contain sulfur. They are in particular benzothiophene, dibenzothiophene and their mono- or multisubstituted, more specifically 4-methyldibenzothiophene and 4,6-dimethyldibenzothiophene.
• deulfurization is meant any treatment which makes it possible to reduce the sulfur content of the mixture of hydrocarbons.
• the sulfur-containing compounds can be oxidized, for example to the corresponding sulfoxides, sulfones and sulfonic acids.
• the corresponding sulfoxide has the following structure
• the acid catalyst contains a cation exchange resin having a pKa less than or equal to 4.
• the pKa is advantageously less than or equal to 3, in particular to 2, preferably to 0 and all particularly less than or equal to - 1.74.
• the resin can be chosen from fluorinated resins in which the hydrogen atoms of the hydrocarbon skeleton have been partially or totally substituted by fluorine atoms. Fully fluorinated resins are preferred.
• the resins preferably also contain acid groups.
• the acid groups can be chosen from phenol, arsonic, phosphonic, phosphinic, seleninic, selenonic, sulfinic, sulfonic and carboxylic. Sulfonic and / or carboxylic groups are preferred. Fluorinated resins containing sulfonic groups give good results. Typical structures of fluorinated resins carrying sulfonic groups are described in the publication of MA Harmer et al, J. Am.
• the acid catalyst can consist of the resin alone or it can consist of a matrix in which the resin is dispersed in the form of particles.
• the matrix is preferably inorganic. It most often contains silica, alumina, zirconia or titanium oxide. Pure silica is preferred.
• Nafion ® SAC 13 material marketed by ALDRICH whose synthesis is described in the publication of A. Harmer and aL, J. Am. Chem. Soc. 1996, 118, 7708- 7715.
• the amount of acid catalyst used in the first variant of the process of the invention must be sufficient to allow rapid formation of peracetic acid. It depends on the content of acid sites in the solid acid catalyst and on the concentrations of hydrogen peroxide and acetic acid in the aqueous phase.
• the amount of acid catalyst is such that the number of moles of protons originating from acid groups such as carboxylic and / or sulfonic groups, per kg of aqueous phase with which the catalyst is in contact, is generally greater than or equal to 0.001, in particular to 0.005 and especially to 0.01.
• the amount of acid catalyst is most often such that the number of moles of protons per kg of aqueous phase is less than or equal to 0.8, in particular to 0.5 and very particularly to 0.2. Amounts of acid catalyst which lead to a number of moles of protons per kg of aqueous phase greater than or equal to 0.08 and less than or equal to 0.1 give good results.
• the acid catalyst contains a solid based on silicon oxide which also contains a trivalent metal.
• the silicon / trivalent metal molar ratio in the solid is generally greater than or equal to 3, in particular to 10. This ratio is usually less than or equal to 200, in particular to 175. Values greater than or equal to 12 and less than or equal to 150 give good results.
• the trivalent metal can be chosen from boron, aluminum, gallium and iron. Aluminum is preferred.
• the solid is most often chosen from zeolites, clays and amorphous solids based on silicon oxide further containing a trivalent metal, in particular aluminum. Protonated forms of these solids are preferred.
• H-ZSM-5, H-MOR, H-Beta and H-Y zeolites have given good results.
• H-ZSM-5 and H-MOR zeolites are preferred.
• titanium zeolites give poor results.
• the solid based on silicon oxide used in this variant of the process according to the invention is preferably free of titanium.
• the acid catalyst can consist of the solid alone or it can consist of the solid additionally comprising organic functionalities. These can be chosen from sulfonic and carboxylic organic acid groups and from their mixtures.
• the amount of acid catalyst used in the second variant of the process of the invention must be sufficient to allow rapid formation of the peracetic acid. It depends on the content of acid sites in the solid acid catalyst and on the concentrations of hydrogen peroxide and acetic acid in the aqueous phase.
• the amount of acid catalyst is generally such that the number of moles of trivalent metal per kg of aqueous phase with which the catalyst is in contact is greater than or equal to 0.001, in particular to 0.005 and very particularly to 0.01.
• the amount of acid catalyst is usually such that the number of moles of trivalent metal per kg of aqueous phase is less than or equal to 0.8, in particular to 0.5 and very particularly to 0.2.
• the acid catalyst contains particles of inorganic solid onto which acid organic groups have been grafted such that the particles thus grafted have a pKa less than or equal to 4.
• the pKa is advantageously lower or equal to 3, in particular to 2, preferably to 0 and very particularly less than or equal to - 1.74.
• the inorganic solid can be chosen from oxides of silicon, aluminum, zirconium and titanium. Silicon oxide is preferred.
• the acid organic groups can be chosen from aliphatic, alicyclic, heterocyclic or aromatic groups comprising an acid functionality.
• the acid functionalities can be chosen from phenol, arsonic, phosphonic, phosphinic, seleninic, selenonic, sulfinic, sulphonic and carboxylic functionalities.
• the sulfonic and / or carboxylic functionalities are preferred.
• These groups can contain up to 18 carbon atoms, in particular up to 12 carbon atoms, preferably up to 6. They can also contain one or more heteroatoms such as oxygen and / or fluorine.
• the acid organic groups can be grafted onto the particles of inorganic solid by any suitable known means, such as for example by the method described in the publication by J. H. Clark et al, C.R. Acad. Sci. Paris, Ile Series, Chimie / Chemistry 3 (2000) 399-404.
• the amount of acid catalyst used in the third variant of the process of the invention must be sufficient to allow rapid formation of the peracetic acid. It depends on the content of acid sites in the catalyst and on the concentrations of hydrogen peroxide and acetic acid in the aqueous phase.
• the amount of acid catalyst is generally such that the number of moles of protons originating from acid organic groups per kg of aqueous phase with which the catalyst is in contact, is greater than or equal to 0.001, in particular to 0.005 and very particularly to 0, 01.
• the amount of acid catalyst is usually such that the number of moles of protons per kg of aqueous phase is less than or equal to 0.8, in particular to 0.5 and very particularly to 0.2.
• the catalyst is generally used in the form of particles, which can be obtained by any known process. We think of the most diverse forms of particles such as in particular powders, beads, pellets, extrudates or honeycomb structures. The average size of these particles depends on the type of implementation. For a process where the catalyst is in suspension, the average particle size is generally greater than or equal to 5 ⁇ m, more particularly to 10 ⁇ m and very particularly to 50 ⁇ m.
• the average particle size is usually less than or equal to 500 ⁇ m, more particularly to 250 ⁇ m and more particularly to 150 ⁇ m. Average sizes greater than or equal to 100 ⁇ m and less than or equal to 125 ⁇ m are particularly suitable.
• the average particle size is generally greater than or equal to 0.5 mm, more particularly to 1 mm and very particularly to 2 mm.
• the average particle size is commonly less than or equal to 100 mm, more particularly 75 mm and very particularly 50 mm. Average sizes greater than or equal to 5 mm and less than or equal to 30 mm are particularly suitable.
• the oxidation is generally carried out at a temperature greater than or equal to 0 ° C., in particular at 10 ° C. and preferably at 20 ° C.
• the temperature is usually less than or equal to
• hydrogen peroxide is generally used in the oxidation reaction in the form of an aqueous solution. Before mixing with acetic acid, this solution most often has a hydrogen peroxide concentration greater than or equal to 1% by weight, in particular 10% by weight.
• the hydrogen peroxide concentration is commonly less than or equal to 80%, in particular 70%.
• a concentration of 30 to 60% by weight is suitable.
• the amount of hydrogen peroxide present in the oxidation reaction medium depends on the amount of sulfur present in the mixture of hydrocarbons.
• the molar ratio between hydrogen peroxide and sulfur is generally greater than or equal to 1, in particular to 2. This ratio is often less than or equal to 5000, in particular to 3000.
• the ratios of 3 to 1500 are suitable particularly well.
• acetic acid is generally used in the oxidation reaction in the form of an aqueous solution.
• the molar ratio between acetic acid and the hydrogen peroxide used in the oxidation reaction medium is generally greater than or equal to 0.01, in particular to 0.1 and very particularly to 0.25. This ratio is often less than or equal to 4, in particular to 2. The ratios of 0.5 to 1.5 are particularly suitable.
• the aqueous phase which comes into contact with the mixture of hydrocarbons is used in a volume such that the ratio of the volumes of this aqueous phase and of the mixture of hydrocarbons ensures optimum dispersion of the phases.
• This ratio is generally less than or equal to 0.5, in particular 0.3. It is usually greater than or equal to 0.01, in particular 0.05. Values greater than or equal to 0.1 and less than or equal to 0.25 are preferred.
• the oxidation can be carried out at atmospheric pressure or at an atmospheric pressure. We prefer to work at atmospheric pressure.
• the oxidation can be preceded by one or more hydrodesulfurization steps. It can also be followed by one or more stages of separation of the oxidized sulfur compounds. These separations can be carried out in different ways: distillation, extraction by means of solvents, adsorption on solids, pyrolysis, acid or basic hydrolysis and precipitation.
• the process according to the invention can be carried out continuously or batchwise.
• the method is carried out continuously using the installation shown diagrammatically in the figure.
• the oxidation reaction is carried out in tank 1 which is supplied with a mixture of hydrocarbons at the bottom of the tank via line 2 and in solution of hydrogen peroxide and peracetic acid at the top of the tank. by line 3.
• tank 1 two phases are distinguished: an organic phase consisting essentially of the mixture of hydrocarbons, and an aqueous phase containing in particular hydrogen peroxide and peracetic acid.
• the oxidized organic phase which is less dense than the aqueous phase, is eliminated at the head of the tank 1 by the line 4 and it can be transferred to a unit for separating the oxidized sulfur compounds.
• the aqueous phase containing in particular hydrogen peroxide and acetic acid leaves the tank 1 via the line 5 and is transferred to the tank 6, in which the solid acid catalyst is located.
• the latter remains enclosed in the tank 6.
• the hydrogen peroxide reacts with acetic acid under the action of the solid acid catalyst to reform the peracetic acid.
• An aqueous solution containing the peracetic acid thus reformed leaves the tank 6 via the line 3 to join the tank 1.
• the system is supplied with fresh hydrogen peroxide and possibly with fresh acetic acid via the line 7.
• the system can be purged via the pipeline
• Example 1 (not in accordance with the invention) A synthetic solution of benzothiophene (BT) and dibenzothiophene (DBT) in toluene was used to simulate a mixture of hydrocarbons containing sulfur derivatives. Compounds of the benzo- and dibenzothiophene type are difficult to remove by hydrodesulfurization and contribute mainly to the S content of certain petroleum products. 80 g of a solution of benzothiophene (BT, 5.249 g / kg) and dibenzothiophene (DBT) are introduced into a pyrex double jacket reactor equipped with a paddle stirrer and surmounted by a cooler cooled to -20 ° C.
• BT benzothiophene
• DBT dibenzothiophene
• the BT and DBT contents are determined by vapor phase chromatography after 5 h.
• Example 1 The conditions of Example 1 are reproduced except that 0.21 g of 97% H 2 SO 4 is introduced.
• Example 2 Is repeated the conditions of Example 1 except that one introduces 2.25 g of Nafion ® NR50 (beads 7-9 mesh, Aldrich).
• Example 6 (according to the invention)
• Example 7 (according to the invention)
• Example 1 The conditions of Example 1 are reproduced except that 2.25 g of particles of an inorganic solid (silica) grafted with organic acid groups are introduced, obtained by following the procedure described in the publication by JH Clark et al. , CR Acad. Sci. Paris, Ile Series, Chimie / Chemistry 2000, 3, 399-404.
• Example 8 (in accordance with the invention) The oxidation step was carried out on hydrotreated running diesel with a sulfur content of 39 ppm by weight measured by X-ray fluorescence. Analysis by vapor phase chromatography with specific detection sulfur by atomic emission (AED) shows that the sulfur compounds present are substituted dibenzothiophenes, and more particularly 4,6-dimethyldibenzothiophene.

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• 2001
  • 2001-02-26 FR FR0102688A patent/FR2821350B1/fr not_active Expired - Fee Related
• 2002
  • 2002-02-22 CA CA002439162A patent/CA2439162A1/fr not_active Abandoned
  • 2002-02-22 US US10/468,912 patent/US20040154959A1/en not_active Abandoned
  • 2002-02-22 WO PCT/EP2002/001956 patent/WO2002068567A1/fr not_active Application Discontinuation
  • 2002-02-22 EP EP02744899A patent/EP1377652A1/de not_active Withdrawn
  • 2002-02-22 JP JP2002568664A patent/JP2004528416A/ja active Pending

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