WO2017144460A1

WO2017144460A1 - Process for oxidative desulfurization of liquid fuels

Info

Publication number: WO2017144460A1
Application number: PCT/EP2017/053927
Authority: WO
Inventors: Jakob Albert; Peter Wasserscheid; Benjamin BERTLEFF; Johannes CLAUSSNITZER; Wolfgang Korth; Andreas Jess
Original assignee: Friedrich-Alexander-Universität Erlangen-Nürnberg
Priority date: 2016-02-26
Filing date: 2017-02-21
Publication date: 2017-08-31
Also published as: DE102016203120A1

Abstract

The invention relates to processes for oxidative desulfurization of liquid fuels, wherein a reaction system comprising a fluid containing a homogeneous polyoxometallate catalyst is provided as a first phase (5) and a liquid fuel containing organic sulfur compounds is provided as a second phase (9), wherein the first phase (5) and the second phase (9) are commixed to form a phase interface (15), wherein the organic sulfur compounds contained in the second phase (9) are catalytically converted into oxidation products at the phase interface (15) and wherein the oxidation products are transferred from the phase interface (15) into the first phase (5), thereby depleting the second phase (9) of sulphur. The invention further relates to a desulfurization apparatus (1) for liquid fuels which is set up and configured for performance of the process.

Description

Process for the oxidative desulfurization of liquid fuels

The desulphurization of liquid fuels, especially fuels and oils has been receiving high attention for decades. Classic fuels such as diesel fuel and gasoline are derived from petroleum, which consists of its formation from organic material under exclusion of air from hydrocarbon compounds. However, sulfur compounds are also constituents of the crude oil and consequently all liquid fuels derived from crude oil also contain certain amounts of sulfur.

Environmental regulations require liquid fuels to be desulphurized almost completely before they can be used, for example, to power means of transportation such as automobiles, aircraft and ships. For example, within the European Union, the currently permitted sulfur content of diesel fuel and gasoline must not exceed 10 ppmw (parts per million by weight) and 15 ppmw in the USA. Kerosene and light heating oil currently have significantly higher limit values with 3000 ppmw and 1000 ppmw, respectively. However, stricter limits are to be expected in the future as well.

This also applies to marine fuels, which currently contain up to 5% sulfur by weight in most international waters. By the year 2020, however, this content should also be reduced to 0.5% by weight throughout the EU. In the North Sea and the Baltic Sea, limits for the sulfur content of 0.1% by weight have been prescribed since 2015.

In order to be able to comply with the relevant limit values, the desulfurization of the fuels or fuels used is necessary. A well-known desulphurisation technology is hydrodesulfurization (HDS), the hydrogenating conversion of the organic sulfur compounds contained in a fuel to heterogeneous catalysts such as cobalt-molybdenum or nickel-molybdenum fixed bed. Catalysts. The fuel is preheated together with hydrogen-rich gas and reacts within a reactor under pressures of 20 bar to 170 bar at the solid catalyst located there. The hydrogenation reaction taking place on the catalyst ultimately leads to H ₂ S and the hydrogenated hydrocarbon radical RH.

Hydrogenating desulfurization is particularly suitable for the desulfurization of diesel fuel and gasoline, but also for the desulfurization of vacuum gas oil. However, the HDS process in deep desulphurisation reaches its value of 10 ppmw set by the stricter limits

Limits and can only be guaranteed by increased use of energy and resources. In particular, in the case of the high degrees of desulfurization required in industrialized countries, the expense of desulfurization, for example with regard to the necessary pressure and temperature conditions, the required reactor size and the capital and operating costs, is high.

For example, for the desulfurization of pre-desulfurized diesel fuel, a catalyst volume of up to 500 m ^{3 is} needed to desulfurize 400 m ^{3 of} fuel per hour. In the case of gasoline desulphurisation typical overall pressures are 30 bar, the temperatures for the process are in a temperature range between 310 ° C to 370 ° C, for diesel fuel and kerosene are with 40 bar to 100 bar and temperatures between 330 ° C and 400 ° C sharper conditions necessary. The desulphurisation of vacuum gas oils takes place at 170 bar and 425 ° C. Vacuum residue oils, on the other hand, can not be desulfurized at present. Here, in particular, the vanadium content and nickel content in these residues are too large, which would lead to a rapid deactivation of the catalysts used in an HDS desulfurization. Vacuum residue oils are currently thermally cracked, the cracking fractions must then be optionally then desulfurized.

An alternative to classic HDS desulfurization is the oxidative desulfurization of fuels and fuels. From DE 10 2009 003 659 A1 is a A process is known in which sulfur-containing fuel oil with a water-soluble organic acid, such as acetic acid or formic acid, optionally additionally with a supported on a metal oxide transition metal oxidation catalyst or a carbonaceous promoter, and oxygen is contacted under elevated temperature and elevated pressure in a first reaction mixture to create a first oxidized mixture. In a subsequent step, water is added to provide a biphasic mixture comprising a water rich phase and a fuel oil rich phase. Finally, the water rich phase is separated from the fuel oil rich phase to create a purified fuel oil. At least one oxidized sulfur compound may be separated from the first oxidized mixture using a solid-liquid extraction process, for example by an adsorption process, or using a liquid-liquid extraction process to obtain the purified fuel oil. Overall, such processes are complex in terms of apparatus and cost-intensive.

From de Angelis, A. et al., Pure Applied Chemistry, 2007, Volume 79, No. 1 1, pages 1887 to 1894 a method for the oxidative desulfurization of diesel by means of various heteropolyacids (heteropolyacids, HPAs) is known. The catalyst may be a vanadium-containing polyoxometalate catalyst having a keggin structure. The catalyst is supported on HNO 3 pretreated alumina as the carrier material and is brought into contact with the diesel in this form. The catalyst, at the end of its efficacy, can be heat-treated at 250 ° C under a stream of air, i. H. apart from the diesel, to be regenerated.

US 2010/0300938 A1 discloses a process for the oxidative desulfurization of a sulfur-containing hydrocarbon mixture. In this case, the hydrocarbon mixture is contacted with an aqueous oxidizing agent, such as hydrogen peroxide, in the presence of a catalyst for a time sufficient to oxidize at least a portion of the sulfur compounds in the hydrocarbon mixture. The catalyst can is a polyoxometalate with a keggin structure. The oxidized sulfur compounds are removed from the hydrocarbon mixture by a liquid-liquid extraction by means of a polar solvent, for example by means of methanol, acetonitrile or a mixture of 90 parts of acetonitrile and 10 parts of water. The acetonitrile or the methanol can also be used to transfer large quantities of aromatic components from the hydrocarbon mixture into the polar solvent. After extraction, the hydrocarbon mixture is purified by means of an adsorbent to remove remaining sulfur compounds. It is believed that the sulfur compounds to be removed thereby are sulfur compounds poorly soluble in the polar solvent, such as sulfones.

The object of the present invention is to provide a method for producing desulphurised fuels that is improved over the prior art. The object is solved by the features of patent claim 1. Embodiments result from the features of claims 2 to 14.

A second object of the invention is to provide a desulfurization apparatus which is suitable for carrying out such an improved process. This second object is solved by the features of claim 15.

The first object of the invention is achieved according to the invention by a process for the oxidative desulfurization of liquid fuels, wherein a reaction system comprising a fluid containing a homogeneous polyoxometalate catalyst as a first phase and a liquid containing organic sulfur compounds is provided as a second phase, wherein the the first phase and the second phase are mixed to form a phase interface, wherein the organic sulfur compounds contained in the second phase are catalytically converted at the phase interface to oxidation products, and wherein the sulfur-containing oxidation products be transferred from the phase interface in the first phase, whereby the second phase depleted of sulfur. The fluid of the first phase is water. Addition of another solvent and / or excipient to the first phase is not required to carry out the process. The polyoxometalate catalyst is regenerated by oxygen by metering oxygen into the reaction system in molecular form, ie in gaseous form, and by re-oxidizing the polyoxometalate catalyst dissolved in the first phase.

A fluid containing a homogeneous polyoxometalate catalyst is understood in particular to mean a fluid having a dissolved polyoxometalate catalyst. A liquid fuel containing organic sulfur compounds is understood in particular to mean a fuel in which the organic sulfur compounds are present in dissolved form. The organic sulfur compounds contained in the second phase also include oxidized intermediates of the originally contained organic sulfur compounds, which are further oxidized in the course of the process. The oxidation products are thereby transferred from the phase boundary to the first phase, that they dissolve in the first phase. It is therefore a passive process. In order for this to happen and thereby deprive the second phase of sulfur, the catalytic conversion to oxidation products that takes place before must take place until water-soluble sulfur compounds are formed. Sulfur, which is depleted in the second phase, is therefore a water-soluble sulfur compound. In order to obtain a fuel having an ultra-low sulfur content, ie, a sulfur content of below 10 ppmw, it is necessary that the catalytic conversion to oxidation products occur until, at least substantially, all of the sulfur compounds contained in the fuel become water-soluble Sulfur compounds are oxidized. The water-soluble sulfur compounds include in particular sulfate (SO ₄ ^{2 "} ). In a first step, the invention is based on the fundamental knowledge of various physical and chemical separation processes. A common separation process is the extraction. The extraction is based on the mass transfer or the mass transfer at the phase interface between two immiscible phases, wherein in one of the two phases dissolved components with the aid of the second phase, the extractant are dissolved out. This requires - in addition to the mutual insolubility of the phases into each other - the solubility of the components to be extracted in the phase used as extractant.

In a second step, the invention is based on the consideration that, when using such an extractive separation process, the desulfurization of a liquid fuel would require the use of an extractant which is immiscible with the fuel and at the same time enables the mass transfer of the organic sulfur compounds present in the fuel , Since fuels are nonpolar, this is basically suitable as a means of extraction, a polar and thus not soluble in the fuel fluid. However, the problem here is that the organic sulfur compounds contained in fuels, such as thiophenes, thiophene derivatives or sulfides, also do not dissolve in such a polar solvent.

Taking into account the problem described above, the invention now surprisingly recognizes, in a third step, that separation of the organic sulfur compounds present in a liquid fuel is possible if the organic sulfur compounds present in the fuel are converted in advance into products soluble in the phase used as the extraction agent become. This is achieved in the two-phase reaction system according to the invention by the use of a homogeneous polyoxometalate catalyst in the first phase. The polyoxometalate catalyst catalytically converts the organic sulfur compounds contained in the second phase at the phase interface between the first phase and the second phase to oxidation products. In contrast to the US 2010/0300938 A1 In this case, oxidation is carried out until essentially all the sulfur compounds present in the fuel have been converted to water-soluble sulfur compounds. A subsequent purification by a solid phase extraction or extraction by means of methanol, acetonitrile or other organic solvents is not required. Such an organic solvent would have the disadvantage of also extracting aromatic components from the liquid fuel of the second phase. Unlike the method known from US 2010/0300938 A1, the re-oxidation of the catalyst is not carried out by consumable hydrogen peroxide but by oxygen in molecular form, which can be added as needed, to the originally contained but also as intermediates To be formed, the resulting sulfur compounds oxidize until essentially only water-soluble sulfur compounds, such as sulfate or sulfonic acids, are present. The oxidation products formed in the catalytic reaction are soluble in the first phase and there is a mass transfer between the two phases. The oxidation products are converted from the phase interface into the first phase, whereby the second phase depleted of sulfur.

The process according to the invention thus also differs substantially from the process known from de Angelis, A. et al., Pure Applied Chemistry, 2007, Volume 79, No. 11, pages 1887 to 1894, in which the catalyst is immobilized on a solid support is present and regenerated separately from the catalytic reaction at elevated temperature in an air stream. The first phase and the second phase are not or at least not substantially soluble in each other. The phase interface forming between the two phases can be regarded macroscopically as a surface in the unmixed state. During mixing, the phase interface between the two immiscible phases increases. The enlargement of the phase boundary surface results directly from the formation of a temporary emulsion in which one of the two phases forms small droplets which are finely distributed in the other of the two phases. In the mixed state is the phase interface is thus considered microscopically as the sum of all surfaces of the droplets formed.

Both the product formation, ie the catalytic conversion of the organic sulfur compounds to the oxidation products, and the phase transfer of the products formed during the reaction from the second phase to the first phase take place at the phase interface. The formed oxidation products are transferred from the phase interface into the first phase or go on at the phase interface in the first phase. The second phase depletes sulfur during this process.

In other words, after the catalytic oxidation of the organic sulfur compounds at the phase interface and after the conversion of the resulting oxidation products into the first phase, the liquid fuel is essentially free of sulfur or of the undesired organic sulfur-containing compounds. The desulphurised fuel then meets the requirements of the limit values and can be used accordingly.

The above-described process steps of contacting the two phases, the thorough mixing, the catalytic oxidation of the organic sulfur compounds and the mass transfer of the formed oxidation products can be carried out at the phase interface in a common reaction device. The product formation and the product separation can take place in a common process step. Additional apparatuses and / or process steps for separating the oxidation products can be dispensed with. The formed oxidation products are extracted by the fluid of the first phase and thus removed in an integrated separation step from the second phase, the liquid fuel. Overall, it is possible by means of the method, in the two-phase reaction system, the organic sulfur compounds present in the second phase selectively to oxidation products soluble in the first phase, in particular Sul- Fate, sulfonic acids and carboxylic acids, implement and thus targeted to remove from the fuel.

For this purpose, the polyoxometalate catalyst is used. Polyoxonetallates are complex compounds of light transition metals with oxygen. These metal-oxo anion clusters can also contain a large number of heteroatoms. The metal atoms are usually transition metals, in particular vanadium, niobium, tantalum, molybdenum and tungsten. The Polyoxonnetallate can in

Heteropolyanions and isopolyanions are subdivided. Heteropolyanions can contain additional heteroatoms, such as, for example, phosphorus (P), arsenic (As), silicon (Si) or germanium (Ge). Isopolyanions are pure metal oxide networks without heteroatoms. Form hydrogen together with azide

Polyoxonnetallate, heteropolyacids or isopolyacids, which are used as catalysts.

In one embodiment of the invention, the oxidation of the organic sulfur compounds takes place by an oxygen transfer from the polyoxometalate catalyst to the organic sulfur compounds. The polyoxometalate catalyst in its oxidized form thus serves as an oxidant for the organic sulfur compounds. The oxidation usually takes place at the phase interface between the first phase and the second phase during the mixing of the two phases.

In one embodiment, a vanadium-containing polyoxometalate catalyst is used. As a polyoxometalate catalyst, such with a

Polyoxometalat ion of the general formula [PMo _x V _y O ₄ o] ^{n ~} (HPA-y) are used. HPA-y denotes a heteropoly acid here. Thus, the polyoxometalate catalyst may consist of phosphorus (P), molybdenum (Mo), vanadium (V) and oxygen (O). The indices n, x, y assume integer values in the following ranges: 5 <x <12, 0 <y <7 and 3 <n <10. Furthermore, x + y = 12. Alternatively, mixtures of H ₃ PO, V ₂ O ₅ and MoO ₃ in the respective chiometric ratios of HPA-y with y = 1 to 3 are used as in-situ formed polyoxometalate catalysts.

Water is used as the fluid of the first phase. The liquid fuel (second phase) is usually nonpolar. The organic sulfur compounds are accordingly soluble only in the second phase, the liquid fuel, but not in the first phase. Conversely, this applies to the oxidation products formed in the process according to the invention. These are soluble in the first phase, but not in the second phase. Thus, a separation of the oxidation products from the second phase and their mass transfer into the first phase is particularly effectively possible.

As the organic sulfur compounds, thiophenes, their derivatives, benzothiophenes, their derivatives, sulfides, disulfides and / or thiols can be catalytically oxidized to the oxidation products. The process also allows for the oxidation of less reactive sulfur compounds, such as dibenzothiophenes and 4,6-dialkyldibenzothiophene (4,6-DADBT), such as those found in vacuum resid oils and tar sands. As the oxidation products, sulfates, organic sulfonic acids and / or carboxylic acids can be formed. These oxidation products are polar and soluble in the first phase fluid. As carboxylic acids in particular

short-chain carboxylic acids such as formic acid or acetic acid formed. Formed sulfate (SO ^{2 "} ) can accumulate in the first phase in the form of sulfuric acid (H ₂ SO) or hydrogen sulfate (HSO ₄ ^" ). As a result, the pH of the first phase decreases, whereby the activity of the polyoxometalate catalyst can be enhanced.

In one embodiment, the sulfur depleted second phase is withdrawn for further use. By the method, the sulfur content of the liquid fuel can be lowered so much that this under adherence to the predetermined limits as a liquid fuel, for example for driving Means of transport such as motor vehicles, aircraft and ships.

The oxidation products from the first phase can be separated. For this purpose, it is possible to use classical separation processes such as precipitation, ion exchange, extraction or membrane processes.

To regenerate the polyoxometalate catalyst, the oxygen can be metered into the reaction system in the form of a gas mixture, in particular air or compressed air, and the catalyst dissolved in the first phase can be correspondingly re-oxidized. After oxidative regeneration, the polyoxometalate catalyst is again available for the catalytic conversion of organic sulfur compounds contained in a fuel. In one embodiment, the regeneration of the polyoxometalate catalyst is simultaneous to the oxidation of the organic sulfur compound. The term simultaneously means in the present case that the oxygen necessary for the regeneration of the catalyst is added to the reaction system already during the oxidation of the organic sulfur compounds. The desulfurization of the fuel and the regeneration of the catalyst thus occur in one process step and thus under the same conditions, such. B. pressure and temperature. Usually both processes take place within the same reaction vessel. As fuels, in particular liquid fuels can be desulfurized. In particular, liquid fossil fuels, ie fuels from fossil fuels, can be desulfurized. The fossil fuels are usually derived from oil or coal. These include, in particular, gasoline, diesel, kerosene and fuel oil, as well as lubricants derived from petroleum or coal. Furthermore, biofuels can be desulfurized from renewable raw materials, ie vegetable origin, as liquid fuels. This includes, for example, rapeseed oil and biodiesel (rapeseed methyl ester, RME). In one embodiment, the catalytic reaction of the organic sulfur compounds to the oxidation products takes place at a temperature in a range between 70 ° C and 180 ° C, in particular at a temperature in a range between 90 ° C and 140 ° C. The catalytic conversion of the organic sulfur compounds to the oxidation products can at a pressure in a range between 1 bar and 100 bar, in particular at a pressure in a range between 1 bar and 50 bar, in particular at a pressure in a range between 1, 5 bar and 20 bar, are performed. The pressure may be the total gas pressure or the partial pressure of the oxygen in molecular form.

In particular, the process allows desulfurization of a liquid fuel having a relative sulfur content in a range between 500 ppmw and 12,000 ppmw. The unit ppmw (parts per million weight) indicates the sulfur content in a fuel or in a liquid fuel in millionths of the total mass. After desulphurisation, the fuel is depleted of sulfur to such an extent that it meets the requirements for the limit values required for use.

The process according to the invention can be carried out both continuously and batchwise, ie. H. in a batch process.

The second object of the invention is achieved according to the invention by a desulfurization device for liquid fuels, for carrying out the method according to one of the above-described embodiments, comprising a reaction vessel, a first feed for a homogeneous polyoxometalate catalyst-containing fluid as a first phase, a second Feed for a liquid containing organic sulfur compounds as a second phase, and an agitator for mixing the first phase and the second phase within the reaction vessel. Furthermore, the desulfurization device comprises a feed line for oxygen in molecular form, in particular in the form of a gas mixture, such as. As air, for the regeneration of the homogeneous polyoxometalate catalyst. The feed line is connected to the reaction vessel of the desulfurization device. The desulfurization device according to the invention is set up and designed in particular for carrying out the method according to the invention.

About the first inflow, the first phase, so the one homogeneous

Polyoxonnetallat catalyst containing fluid dosed into the reaction vessel. The second inlet is used to supply the second phase, that is, the organic sulfur compounds containing liquid fuel. Both phases are intensively mixed within the reaction vessel, whereby a large mass transfer area required for the mass transfer between the two phases is formed. The organic sulfur compounds contained in the second phase are oxidized by the polyoxonetalate catalyst and thus converted into soluble in the first phase of the oxidation products. At the phase boundary, the mass transfer takes place, the oxidation products are transferred to the first phase. The second phase, ie the liquid fuel, is thereby desulfurized. The desulphurisation device comprises a first outlet for removing the first phase. The first sequence is usually arranged on the reaction vessel. The oxidation products dissolved in the first phase can be fed to a treatment device and separated there from the first phase. Furthermore, the desulfurization device comprises a second outlet for removing the sulfur-depleted second phase. Usually, the second sequence is arranged on the reaction vessel. The second phase is fed to its further use after the removal of the organic sulfur compounds.

Further embodiments of the desulfurization resulting from the subclaims directed to the method. It can be for the Procedures and its developments named benefits are mutatis mutandis transferred to the desulfurization.

In principle, it has been shown on the basis of our own investigations that the sulfur-containing organic compounds dissolved in a fuel (second phase), with the aid of water-soluble polyoxometalate catalysts, are selective in a two-phase system to water-soluble sulfur components, in particular sulphate, sulphonic acids and carboxylic acids, be oxidized. The fuel is not attacked. The sulfate or sulfonic acid formed is extracted through the polar phase in which the polyoxometalate catalyst is dissolved (first phase), and can be removed from the fuel in an integrated separation step.

To determine the sulfur content of the second phase, a sulfur elemental analyzer from Antek was used. Analysis of the first phase of the catalyst was carried out by means of NMR spectroscopy (short-chain carboxylic acids), atomic emission spectroscopy (ICP-OES), and ion chromatography (IC). Gaseous products (CO ₂ and CO from the sulfur compound) were detected by gas chromatography. The mass balances for carbon (C) and sulfur (S) could be concluded with the help of the analytics used. Depending on the type of sulfur compound used, up to 90% of the sulfur was converted from the second phase to the first phase as sulfate or sulfonic acid. Additionally, to study the distribution and behavior of the

Polyoxometalate Catalyst ³¹ P and ⁵¹ V NMR samples of both the first (polar) and second (nonpolar) phases were analyzed. In this case, no transition of the catalyst in the second phase, ie in the organic fuel could be detected.

In the following an embodiment will be explained in more detail with reference to a drawing. FIG. 1 shows a schematic desulfurization device 1 for liquid fuels, in particular fuels. The desulfurization device 1 comprises a reaction vessel 3, in which both the desulphurisation of a fuel and the separation of the products formed during the desulfurization takes place. The reaction vessel 3 is formed as a high-pressure autoclave.

A fluid containing a homogeneous polyoxometalate catalyst is metered as the first phase 5 into the reaction vessel 3 via a first inlet 7. In the present case, 0.9 g of the polyoxometalate catalyst 4 H ₈ [PMo7V ₅ O] are dissolved in 200 ml of water. Via a second feed 11, a second phase 9, in the present case 3.36 g of benzothiophene dissolved in 69 g of isooctane, is metered in as the liquid fuel or fuel. In the present case, the inlets 7, 11 are only indicated diagrammatically by arrows. The same applies to the supply line 13, which serves for the metering of oxygen for the regeneration of the polyoxometalate catalyst used. With regard to the arrangement of the respective inlets 7, 1 1 and the supply line 13 to the reaction vessel 3, this can of course also be done elsewhere.

Since the two phases 5.9 are not miscible with each other, they are separated from each other before mixing by a visible with the naked eye phase boundary 15. Then the two phases 5, 9 im

High pressure autoclave 3 mixed at 1000 rpm for a period of 24 hours at a temperature of 140 ° C and an oxygen partial pressure of 20 bar. For mixing a stirrer 17 is used.

As a result of the thorough mixing, the phase boundary surface 15 between the immiscible phases 5, 9 no longer has a macroscopic surface, but increases markedly due to droplet formation, which increases the mass transfer area and thus improves mass transfer. This is not outlined here. At phase interface 15, both the product images and tion, ie the catalytic conversion of the organic sulfur compounds to the oxidation products, as well as the mass transfer of the products from the second phase 9 to the first phase 5 instead. The formed oxidation products are transferred from the phase interface 15 into the first phase 5. The second phase 9 depletes of sulfur during this process.

After completion of the reaction, the reaction mixture is cooled to room temperature and the two phases 5, 9 separated. The polar first phase 5 can be removed via a first outlet 19. If the first phase 5 is again used for the desulfurization of a liquid fuel, it remains in the high-pressure autoclave 3. Otherwise, the first phase 5 can be removed and the in the first phase 5 dissolved oxidation products are removed from this. The sulfur depleted second phase 9 is removed from the high-pressure autoclave 3 via a second outlet 21. The desulphurised fuel or fuel then meets the requirements of the specified limits and can continue to be used accordingly. The regeneration of the dissolved in the first phase 5, homogeneous polyoxometalate catalyst is carried out by molecular oxygen or compressed air. The regeneration of the polyoxometalate catalyst takes place here simultaneously to the oxidation of the organic sulfur compounds at the phase interface 15. To regenerate the catalyst, oxygen is added to the first phase 5 in molecular form, in particular in a diluted form, such as compressed air or synthetic air, and the catalyst is re-charged. oxidized. After the regeneration is the

Polyoxometalate catalyst again for the catalytic conversion of organic sulfur compounds available. By means of the method, it is thus possible, in a two-phase reaction system consisting of a fuel with dissolved organic sulfur compounds as the second phase 9 and a polar first phase 5 having therein dissolved Polyoxonnetallat catalyst to selectively oxidize the organic Schwefelkomponen- to soluble in the first phase polar components and remove them targeted from the fuel. As gaseous by-products arise CO ₂ and CO.

LIST OF REFERENCE NUMBERS

1 desulfurization device

3 reaction vessels

5 first phase

7 first inlet

9 second phase

1 1 second inlet

13 supply line

15 phase interface

17 agitator

19 first sequence

21 second sequence

Claims

claims

Process for the oxidative desulphurisation of liquid fuels,

wherein a reaction system comprising a fluid containing a homogeneous polyoxonetalate catalyst as a first phase (5) and an organic sulfur compound-containing liquid fuel is provided as a second phase (9), the first phase (5) and the second phase (9) are mixed with formation of a phase interface (15),

wherein the organic sulfur compounds contained in the second phase (9) are catalytically converted to oxidation products at the phase interface (15), and

wherein the oxidation products are transferred from the phase interface (15) to the first phase (5), whereby the second phase (9) depleted of sulfur,

wherein the polyoxonetalate catalyst is regenerated by oxygen by dosing oxygen into the reaction system in molecular form and thereby reoxidizing the polyoxonetalate catalyst dissolved in the first phase,

wherein the fluid of the first phase (5) is water.

The process of claim 1, wherein the catalytic conversion of the organic sulfur compounds to the oxidation products occurs by oxygen transfer from the polyoxonetalate catalyst to the organic sulfur compounds.

The method of claim 1 or 2, wherein the polyoxonetalate catalyst is a vanadium-containing polyoxonetalate catalyst.

Method according to one of the preceding claims, wherein the

Polyoxonetalate Catalyst A polyoxometalate ion of general formula mel [PMo _x V _y O ₀ ] ^{n "} , where 5 <x <12 and 0 <y <7 and 3 <n <10 and x + y = 12, where n, x and y each take integer values.

5. The method according to any one of the preceding claims, wherein as the organic sulfur compounds thiophenes, their derivatives,

Benzothiophenes whose derivatives, sulfides, disulfides and / or thiols are catalytically converted to oxidation products.

6. The method according to any one of the preceding claims, wherein as the oxidation dationsprodukte sulfates, organic sulfonic acids and / or carboxylic acids are formed.

7. The method according to any one of the preceding claims, wherein the

Sulfur-depleted second phase (9) is subtracted for further use.

8. The method according to any one of the preceding claims, wherein the oxidation onsprodukte from the first phase (5) are separated.

9. The method according to any one of the preceding claims, wherein the oxygen is added to the reaction system in the form of a gas mixture, in particular air or compressed air.

10. The method according to any one of the preceding claims, wherein the regeneration of the polyoxometalate catalyst is carried out simultaneously to the catalytic conversion of the organic sulfur compound.

1 1. Method according to one of the preceding claims, wherein as the

Fuel a liquid fuel is desulfurized.

12. The method according to any one of the preceding claims, wherein the catalytic conversion of the organic sulfur compounds to the Oxidati- onsprodukten at a temperature in a range between 70 ° C and 180 ° C.

13. The method according to any one of the preceding claims, wherein the catalytic conversion of the organic sulfur compounds to the oxidation onsprodukten at a pressure in a range between 1 bar and

100 bar.

14. The method according to any one of the preceding claims, wherein the liquid fuel has a relative sulfur content in a range between

500 ppmw and 12000 ppmw.

15. A liquid fuel desulfurization device (1) for carrying out the method according to one of claims 1 to 14, comprising a reaction vessel (3), a first feed (7) for a homogeneous polyoxometalate catalyst-containing fluid as a first phase (5 ), a second feed (11) for an organic sulfur compound-containing liquid fuel as a second phase (9), an agitator (17) for mixing the first phase (5) and the second phase (9) within the reaction vessel (3) , an oxygen supply line (13) connected to the reaction vessel (3) for regenerating the homogeneous one

Polyoxometalat catalyst, a first outlet (19) for taking out the first phase (5) and a second outlet (21) for removing the sulfur-depleted second phase (9).