FR2818990A1 - PROCESS AND DEVICE FOR DESULFURIZING CHARGED HYDROCARBONS IN THIOPHENIC DERIVATIVES - Google Patents

Abstract

The invention relates to a selective desulphurisation method for thiophene derivatives contained in the hydrocarbons emitted from the distillation of crude oil, refined or not, consisting in oxidising the atoms of thiophene sulphur in sulphone in the presence of an oxidising agent and separating the sulphonated compounds from said hydrocarbons. This inventive method comprises at least one first stage involving the oxidation/absorption by heterogeneous catalysis of the sulphurous compounds in an organic environment, at a temperature of at least 40<C, at atmospheric pressure in the presence of an organic oxidiser from the family of peroxides and peracids, in the presence of a catalyst having a specific surface area greater than 100m2/g and a porosity varying from 0.2 to 4ml/g, and a second stage wherein the used catalyst is regenerated.

Description

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METHOD AND DEVICE FOR DESULFURIZING CHARGED HYDROCARBONS IN THIOPHENIC DERIVATIVES.

 The present invention relates to a process and a device for the desulphurization of hydrocarbons, in particular for the desulfurization of fuel bases for gas oils, kerosines and gasolines. In particular, it relates to the desulfurization of fuels bases loaded with dibenzothiophene compounds.

 The presence of sulfur in fuels is a problem considered today as a major concern for the environment.

In fact, by combustion, sulfur is converted into various sulfur oxides, which can be converted into acids, thus contributing to the formation of acid rain.

 Generally, refineries use catalytic hydrodesulfurization processes to lower the sulfur content of fuels.

 Thus, the gas oils obtained directly from the distillation are hydrotreated between 300 and 400 ° C., under a hydrogen pressure varying between 30 and 100 bar (30 to 100 × 10 5 Pa), in the presence of a catalyst arranged in a fixed bed and consisting of sulphides of groups VIb and VIII metals deposited on alumina, for example cobalt and molybdenum sulphides or sulphides of nickel and molybdenum. Given the operating conditions and the hydrogen consumption, these processes can be costly in terms of investment and operation, particularly if it is desired to produce fuels with a very low sulfur content. Thus, to desulphurize a fuel initially containing 1% by weight of sulfur, up to a sulfur content of between 0.05 and 0.005% by weight, the size of the reactor can be multiplied by 4 and the amount of hydrogen required for the reaction should be increased by about 20%. It is particularly difficult, by such methods, to remove traces of sulfur, especially if the sulfur belongs to refractory molecules such as dibenzothiophene alkylated in position 4, or 4 and 6.

 In some countries, such as Sweden, the United States, particularly in California, and others, the total sulfur content of gas oils is already limited to 0.005% by weight. This limitation could be

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généraliser à terme dans les pays de l'OCDE. Pour l'Europe, cet objectif de 0, 005 % en poids de soufre totale devrait être atteint en 2005.

generalize over time in OECD countries. For Europe, this objective of 0.005% by weight of total sulfur should be reached in 2005.

 Unlike gas oils, gasolines do not come only from the direct distillation of crude oil, these species being then weakly sulfurized, but can also be obtained by several processes such as the reforming of naphthas, the isomerization of light naphthas, alkylation butane or propane producing isooctane, isobutene methoxylation and catalytic cracking of vacuum distillates or atmospheric residues. In particular, catalytic cracking provides between 20 and 60% by weight of the final gasoline. These species contain up to 0.1% by weight of sulfur. It is therefore common to desulphurize the species from catalytic cracking by processes similar to those described for the hydrodesulfurization of gas oils, for which the operating conditions are more severe in hydrogen pressure, space velocity and temperature. These processes, although expensive, do not however achieve conventional levels of total sulfur, in these cracking species, between 0.005 and 0.03% by weight. Although, in order to reduce this sulfur content, the refiners have thought of adding to the cracking catalyst additives decomposing the sulfur compounds forming during the process, in particular mercaptans and sulphides, these additives have only one effect. limited, if any, on benzothiophene derivatives, even when mercaptans and sulphides were removed before cracking.

 In the case of sulfur-producing catalytic cracking gasolines in gasolines, hydrodesulphurization is not only inefficient with respect to thiophene compounds, but is also destructive to the octane number of the gasoline species. petrol. In fact, during the hydrodesulfurization reaction, there is partial hydrogenation of the olefins contained in these cracking gasolines, their disappearance resulting in a lowering of the octane number of the gasoline and thus a deterioration of the quality of gasoline. To compensate for this loss, it is possible to introduce other constituents to improve this index or to reprocess the gasoline itself to increase this index.

The addition of additive or reprocessing to improve the quality of the gasoline strike all its cost price, and it is therefore advantageous to have a treatment process to eliminate directly

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les composés soufrés réfractaires, comme les dérivés benzothiophèniques, en limitant l'utilisation d'hydrogène.

refractory sulfur compounds, such as benzothiophene derivatives, by limiting the use of hydrogen.

 Methods for selectively oxidizing sulfur compounds are among the treatment methods that can accomplish this goal. Among the methods and processes developed to reduce the amount of sulfur present in fuels in the form of thiophene derivatives, oxidation by organic peroxides, organic hydroperoxides, hydrogen peroxide and organic peracids has been envisaged either without catalyst, or by homogeneous catalysis in the presence of catalysts based on organometallic compounds or metal oxides in aqueous phase (see US 3,668,117, US 3,565,793, EP 0 565 324 and the publications of TA KOCH, KR KRAUSE, L EMANZER, H. MEHDIZADEH, JM ODOM, SK SENGUPTA, New J. Chem., 1996, 20, 163-173 and FM COLLINS, AR LUCY, C. SHARP, J. of Molecular Catalysis A: Chemical 117 (1997) 397-. 403).

 For processes using metal catalysts based on molybdenum and tungsten in the presence of hydrogen peroxide in aqueous solution (heterogeneous catalysis), it operates at temperatures above 60 oC and there is overconsumption of hydrogen peroxide part of this oxidant being decomposed by the catalyst used. The peracids used, very powerful oxidants, obtained by reaction of hydrogen peroxide and a carboxylic acid such as formic acid or acetic acid, are generally less effective than hydrogen peroxide and less selective vis-à-vis -vis sulfur compounds and can oxidize especially olefins.

 Other processes of oxidesulfurization in an organic medium have been proposed: they consist in contacting, in the form of powder, metal oxides or in forming metal compounds comprising peroxo groups in aqueous or organic solutions with the hydrocarbons containing these sulfur-containing refractory compounds , in the presence or absence of organic or aqueous peroxides, these being introduced with a solvent alcohol or in water (see US 3,816,301, US 4,956,578, US 5,958,224).

 Another method, described in US Pat. No. 3,945,914, is to produce a desulfurized hydrocarbon material in three treatment steps. The first step is to oxidize at least

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partiellement les composés soufrés par mise en contact avec des peroxydes, en présence de catalyseurs métalliques contenant des métaux du groupe comprenant le titane, le zirconium, le molybdène, le tungstène, le vanadium, le tantale, le chrome et leurs mélanges, sous forme liquide ou solide éventuellement supportée, les supports n'étant pas essentiels pour la réaction. La deuxième étape consiste à mettre en contact la matière hydrocarbonée contenant ces composés oxydés avec un autre composant métallique, oxyde ou peroxyde métallique (métaux du groupe comprenant le nickel, le molybdène, le cobalt, le tungstène, le fer, le zinc, le vanadium, le cuivre, le manganèse, le mercure et leurs mélanges), à une température variant de 250 à 730OC, sous pression d'hydrogène. La troisième étape consiste à récupérer la matière hydrocarbonée dé sulfurée
Dans toutes ces méthodes et procédés, on transforme les dérivés du thiophène en leur forme sulfonée et/ou sulfonique.

partially sulfur compounds by contact with peroxides, in the presence of metal catalysts containing metals of the group comprising titanium, zirconium, molybdenum, tungsten, vanadium, tantalum, chromium and their mixtures, in liquid form or solid possibly supported, the supports not being essential for the reaction. The second step consists in bringing the hydrocarbon material containing these oxidized compounds into contact with another metal component, metal oxide or peroxide (metals of the group comprising nickel, molybdenum, cobalt, tungsten, iron, zinc, vanadium , copper, manganese, mercury and their mixtures), at a temperature ranging from 250 to 730OC, under hydrogen pressure. The third step is to recover the hydrocarbon material from sulphide
In all these methods and processes, the thiophene derivatives are converted into their sulphonated and / or sulphonic form.

However, for some of these compounds, even if working at high temperature, the reaction is relatively slow and the total conversion is not reached in less than one hour, otherwise using very high concentrations of oxidant, often very high. greater than the quantities necessary for the oxidation of sulfur derivatives. In other cases, it is possible to work in several stages, but which are costly in terms of time and unit tracking.

 The present invention therefore aims at providing a process for the desulfurization of hydrocarbons, in particular those used as fuels bases containing thiophene derivatives, without decreasing the octane number or the cetane number index, sometimes even with an increase in these hydrocarbons. indices. It relates particularly to the finishing treatment of hydrotreated gas oils, kerosines and catalytic cracking gasolines, highly concentrated in thiophene derivatives refractory to hydrogenations.

 The invention also aims to propose such a process which makes it possible to reach oxidation levels identical to, or better than, the known processes, while limiting the reaction and separation times of the oxidized sulfur compounds of the desulfurized hydrocarbons.

 The subject of the present invention is therefore a process for the selective desulfurization of the thiopheneic compounds contained in the

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hydrocarbures issus de la distillation du pétrole brut, raffinés ou non, consistant à oxyder les atomes de soufre thiophénique en sulfones en présence d'un agent oxydant et d'un catalyseur, et à séparer les composés sulfonés obtenus des dits hydrocarbures, ce procédé étant caractérisé en ce qu'il comprend au moins une étape d'oxydation par catalyse hétérogène des composés soufrés, en milieu organique, à une température d'au moins 40OC, en présence d'un oxydant organique de la famille des peroxydes et des peracides et en présence d'un catalyseur

de surface spécifique supérieure à 100 m2/g et de porosité variant de 0,2 à 4 ml/g, et éventuellement une étape de régénération du catalyseur.

hydrocarbons derived from the distillation of crude oil, refined or not, consisting in oxidizing the thiophene sulfur atoms to sulfones in the presence of an oxidizing agent and a catalyst, and in separating the sulphonated compounds obtained from said hydrocarbons, this process being characterized in that it comprises at least one oxidation step by heterogeneous catalysis of the sulfur compounds, in an organic medium, at a temperature of at least 40 ° C., in the presence of an organic oxidant of the peroxide and peracid family and in the presence of a catalyst

with a specific surface area greater than 100 m 2 / g and a porosity ranging from 0.2 to 4 ml / g, and optionally a catalyst regeneration step.

 In the context of the present invention, the term "thiophene derivatives" means benzothiophene compounds, polybenzothiophenic and their alkyl derivatives, among which alkyldibenzothiophenes, particularly refractory to the conversion processes usually used by refiners.

 The process according to the invention has the advantage of carrying out at atmospheric pressure an oxidation of all the sulfur contained in the hydrocarbons, but more selectively a conversion of thiophene derivatives to sulfones and this in the context of a simple industrial process. The separation of hydrocarbons from a portion of the sulfones formed is immediate, these being found in solid form deposited on the catalyst or in the form of filterable deposit by means known per se in the treated hydrocarbons. The sulfones still dissolved in the treated hydrocarbons can be extracted by means of a sulfur trap. Moreover, this oxidation has no effect on olefins, which does not modify, in the catalytic cracking gasoline, the octane number or the content of unsulfurized aromatic compounds. The oxidation process according to the invention also improves the cetane number of the gas oils.

 Without being limited by theory, it appeared that the greater the specific surface area of the catalyst, the longer it is active. Similarly, the larger the pore size, the less the catalyst pore is likely to clog quickly, and the longer the catalyst lasts during the oxidation cycle. For the present invention, it is a question of selecting the catalyst which presents

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le meilleur compromis en surface spécifique et en taille des pores pour obtenir une activité suffisante et cela le plus longtemps possible.

the best compromise in specific surface area and pore size to obtain sufficient activity for as long as possible.

 When the process is carried out continuously intermittently, the oxidation and regeneration steps can be carried out successively, the oxidation preceding the regeneration. For example, these steps can be carried out in the same reactor or simultaneously in two reactors arranged in parallel and operating alternately for one or other of the fixed-bed steps, or in at least two connected moving-bed reactors. one to the other by the catalytic bed, one being dedicated to oxidation, the other to regeneration.

 In a fixed bed, the first reactor containing a fixed catalyst bed receives the hydrocarbon and oxidant streams and the second reactor receives, for the regeneration of the catalyst, liquid effluents, for example a washing solvent, or oxidizing gaseous effluents. , such as air or an air / N2 mixture, the temperature of the catalytic bed being raised. These reactors change their function when the efficiency of the catalyst in the oxidation reactor is no longer sufficient for oxidation.

 In a moving bed, the hydrocarbons are brought into the first reactor where the oxidation takes place, the catalyst being progressively pushed towards the second reactor, where it is regenerated before being returned to the oxidation reactor. Reactors with moving beds, well known in particular in the field of reforming, can be used in this device. In this embodiment, a third reactor is used which is disposed between the first two reactors and makes it possible to remove the hydrocarbons from the used catalyst before washing it or to burn the trapped sulfones.

 The catalysts used according to the present invention are chosen from the supports of the group consisting of silicas, aluminas, zircons, amorphous or crystalline aluminosilicates, aluminophosphates, silicic and silicoaluminated mesoporous solids, activated carbons and clays, these supports. being used alone or in mixture. In the catalysts of the invention, these supports can be advantageously used as supports for metals of the group consisting of titanium, zirconium, vanadium, chromium, molybdenum, iron, manganese, cerium and tungsten, these metals

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sous forme d'oxydes pouvant être introduits dans le réseau du support ou déposés en surface du support. En effet, on a constaté dans certains cas un effet synergique du métal avec le support, c'est-à-dire une augmentation inattendue de l'activité du catalyseur au regard de l'oxydation des composés thiophéniques.

in the form of oxides that can be introduced into the network of the support or deposited on the surface of the support. Indeed, it has been found in some cases a synergistic effect of the metal with the support, that is to say, an unexpected increase in the activity of the catalyst with respect to the oxidation of thiophene compounds.

 In the process according to the invention, the catalyst contains from 0 to 30% by weight of metal in oxide form on at least one support. Preferably the catalyst contains from 0 to 20% of metal as an oxide.

 Among the supports consisting of refractory oxides are gamma aluminas, silicas, mesoporous silicic and silicoaluminated solids.

 Among the supported catalysts, catalysts containing tungsten or titanium in the form of oxide deposited on a support or introduced into the network are preferred, this support being chosen from silicas, aluminas and aluminosilicates, alone or as a mixture.

 In a preferred mode of implementation of the process, the total oxidant / sulfur molar ratio contained in the hydrocarbons is between 2 and 20, and preferably between 2 and 6.

 According to the invention, the oxidants are chosen from compounds of general formula ROOR 2, in which R 1 and R 2 are identical or different, chosen from hydrogen, linear or branched alkyl groups comprising from 1 to 30 carbon atoms and aryl or alkylaryl groups whose aryl unit is optionally substituted by alkyl groups, Ri and R2 can not be simultaneously hydrogen.

 In a preferred embodiment, the oxidant of formula RIGOR 2 is selected from the group consisting of tert-butyl hydroperoxide and di-tert-butyl peroxide.

 Other oxidants of the invention, the peracids of formula R3COOOH, are chosen such that R3 is hydrogen or a linear or branched alkyl group comprising from 1 to 30 carbon atoms. They are preferably selected from the group consisting of peracetic acid, performic acid and perbenzoic acid.

r formés. In the process of the invention, the catalyst regeneration step consists of washing or burning the deposits.

r trained.

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For the washing, a preferably polar solvent of the group consisting of water is used, the linear or branched alkanols comprising from 1 to 30 carbon atoms, alone or as a mixture with water, the alkylnitriles comprising from 1 to 6 carbon atoms. Water, acetonitrile, methanol and mixtures thereof are preferred.

 By combustion, the catalyst is brought to a temperature of at most 800 ° C., preferably at a temperature of less than or equal to 650 ° C., under a pressure ranging from 105 Pa to 106 Pa, and preferably from 105 Pa to 2 × 105 Pa, in the presence of an oxidizing gas. Oxidizing gas is understood to mean pure oxygen and all oxygen-containing gas mixtures, especially oxygen and nitrogen mixtures and air itself. The amount of oxygen in the nitrogen is adjusted so as to limit the formation of water vapor, an excessive amount of water vapor having the side effect of modifying the structure of the pores of the catalyst with reduction of their volume, especially when it contains as support crystalline aluminosilicates such as zeolites or aluminophosphates. This adjustment also makes it possible to control the temperature variations related to the exothermicity of the combustion.

 A second object of the invention is a device for carrying out the process defined above, this device comprising at least a first reactor containing an oxidation catalyst and comprising hydrocarbon inlet pipes and oxidant and an outlet pipe desulfurized hydrocarbons, and optionally a second reactor comprising solvent inlet pipes or oxidizing gas of the catalyst, in order to regenerate it, and a flue gas outlet pipe. By oxidizing gas is meant here the oxygen / air, air / nitrogen and oxygen / nitrogen mixtures.

 When the device comprises two reactors, the reactors can operate in a fixed bed or in a moving bed.

 A third object of the invention is the application of the method defined above to the specific finishing treatment of gasoline from catalytic cracking or the treatment of gas oils having previously been hydrotreated and kerosene, for a better economy of the process.

 The invention will be described hereinafter in more detail with reference to the accompanying drawings. On these drawings:

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La figure 1 est un schéma d'un dispositif à deux réacteurs fonctionnant alternativement en oxydation et en régénération du catalyseur ;
La figure 2 est un schéma d'un dispositif comprenant deux réacteurs à lit mobile, le premier correspondant à l'étape d'oxydation, le second à l'étape de régénération du catalyseur, un conduite de retour du catalyseur régénéré étant adjointe au système.

Figure 1 is a diagram of a two-reactor device operating alternately in oxidation and regeneration of the catalyst;
FIG. 2 is a diagram of a device comprising two moving-bed reactors, the first one corresponding to the oxidation stage, the second one to the catalyst regeneration stage, a return line of the regenerated catalyst being added to the system; .

 The device of FIG. 1 comprises two reactors 1 and 2 loaded with a catalyst arranged in a fixed bed. When the reactor 1 operates in oxidation and the reactor 2 operates in regeneration, the pipe 3 brings to the reactor 1 the sulfurized hydrocarbon feedstock, into which the oxidant has been introduced via the pipe 4, the three-way valve 6a and the pipe 8a. . The desulphurized hydrocarbon stream exits the reactor 1 through line 9a and joins the conduit 10a for removing the desulphurized hydrocarbons via the three-way valve 7a.

température du lit catalytique est maintenue à 500OC. Le solvant contenant les sulfones récupérés sur le catalyseur ou les gaz de combustion, S02, CO et CO2 principalement, sont évacués via la

conduite 9b, la vanne trois voies 7b et la conduite 1 lob dans la conduite lia. At the same time, line 5 brings to reactor 2 either an appropriate solvent or an oxidizing gas via the three-way valve 6b and line 8b. When the reactor is burning, the

Catalytic bed temperature is maintained at 500OC. The solvent containing the sulfones recovered from the catalyst or combustion gases, mainly SO2, CO and CO2, is removed via the

pipe 9b, the three-way valve 7b and the pipe 1 lob in the pipe 11a.

la vanne 7b et la conduite 1Ob. When the regeneration of the catalyst is made and the activity of the reactor 1 catalyst becomes insufficient, the function of the two reactors is changed. Thus, the hydrocarbon / oxidant mixture borrows the pipe 3a and the valve 6b to enter the reactor 2. The desulfurized hydrocarbons are discharged through the pipe 9b and are directed to the discharge pipe 10a via

the valve 7b and the pipe 1Ob.

In parallel, the solvent or the oxidizing gas arriving via the pipe 5 is directed into the reactor 1 via the pipe 3a, the valve 6a and the pipe 8a. The solvent or the oxidation gases are brought back into the evacuation pipe 1 via line 9a and valve 7a.

 The valves 6a, 6b, 7a and 7b can be switched in a common process to allow the flow of proposed flows.

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One of the lines 9a or 9b, or alternatively 10a or 10b, may be advantageously placed on a filter for recovering the solid sulfones formed during the oxidation, which remain in suspension in the hydrocarbons. Sulfur traps equipped with silica or activated alumina adsorbents can advantageously be added to these same pipes, downstream of these filters, to trap the sulfones still dissolved in the treated hydrocarbons.

 The device of FIG. 2 comprises two reactors 20a and 20b, arranged in series, each containing a moving bed of catalyst, the reactor 20a operating in oxidation mode and the reactor 20b operating in regenerative mode, and a propulsion device 30 allowing the return from the reactor 20b catalyst to the reactor 20a.

 The hydrocarbons are fed via line 40 into reactor 20a, after having been doped with the oxidant via line 50. For example, reactor 20a may be chosen from funnel reactors, the moving bed of catalyst moving by gravity towards the lower part of the reactor. Thus, while the desulphurized hydrocarbons are discharged through line 60, the catalyst is pushed by gravity into reactor 20b via line 70. The solvent or the combustion gas is introduced via line 80 into reactor 20b. To perform the regeneration by combustion, the temperature is raised and maintained at 500OC. The solvent charged with sulfones or the combustion gases are evacuated via the pipe 100.

 Since, generally, these mobile beds operate intermittently, the catalyst does not move continuously, it is advantageous to have on the reactor 20b a purge of solvent or nitrogen for the removal of hydrocarbons before washing, and / or the elimination of the flue gases by nitrogen stripping.

 At the outlet of the reactor 20b, the regenerated catalyst is conducted via the pipe 110 to the device 30. This device may be a pressurized gas propulsion device or a worm. It brings the regenerated catalyst via line 120 to the reactor 20a.

 In some particular embodiments of these mobile reactors, the reactors 20a and 20b may be part of the same unit having two separate stages.

 The following examples are intended to illustrate the efficiency of the process of the invention without limiting its scope.

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EXAMPLE 1 The present example aims to describe the efficiency of the process according to the invention with regard to the removal of the dibenzothiophene derivatives present in the bases for partially desulfurized fuels.

 The catalyst samples used are of two types, catalysts formed from a single support and those to which are combined one or more metals deposited by impregnation. Table 1 below gives the characteristics of specific surface area and porosity of each of them.

TABLE 1

<Tb>
<tb> Sample <SEP> Nature <SEP> of <SEP> Surface <SEP> Size <SEP> of <SEP> Oxides
<tb> of <SEP> support <SEP> specific <SEP> metal pores <SEP>
<tb> Catalyst <SEP> (m2 / g) <SEP> (Angstroms)
<tb> CI <SEP> SiO2 <SEP> 160 <SEP> 252 <SEP> C2 <SEP> SiO2 <SEP> 140 <SEP> 300 <SEP> WO3
<tb> C3Al2O3 <SEP> gamma <SEP> 245 <SEP> 104 <SEP> WO3
<tb> C4 <SEP> Zeolite <SEP> beta <SEP> 470 <SEP> 30 <SEP> TiO2
<tb> Cs <SEP> Mesoporous <SEP> 1000 <SEP> 85
<tb> C6 <SEP> Mesoporous <SEP> 830 <SEP> 70 <SEP> MoO3
<Tb>

The catalysts C2, C3 and C6 were obtained by wet impregnation of a metal salt, respectively ammonium metatungstate and ammonium hexamolybdate, at a content of 140 mg of metal per gram of support, then dried and finally calcined at a temperature of 500OC.

 Catalyst C4 was obtained by treating a commercial titanium zeolite beta according to the procedure described in the patent Ego 842 114.

 To test the activity of these oxidation catalysts as a function of time, 20 ml of catalyst was introduced into a micropilot of 150 ml. A medium distillate feedstock after hydrotreatment, containing 212 ppm of residual sulfur refractory to hydrotreatment, doped with 1,800 ppm of tertiobutyl hydroperoxide, is circulated over the catalyst at a hourly space velocity (WH) of 1 hr -1 at atmospheric pressure. Samples are taken regularly

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au cours de l'oxydation pour mesurer l'activité du catalyseur dans le temps. Un échantillon comparatif appelé Ti, correspondant à l'utilisation de catalyseur seul sans peroxyde, est également suivi.

during the oxidation to measure the activity of the catalyst over time. A comparative sample called Ti, corresponding to the use of catalyst alone without peroxide, is also followed.

 In Table II below are given the efficiency results of these catalysts over time.

TABLE II

<Tb>
<tb> Sample <SEP> Catalyst <SEP> Sulfur <SEP> total <SEP> (ppm) <SEP> after <SEP> different
<tb><SEP> periods of <SEP> operation.
<Tb>

2h <SEP> 4h <SEP> 5 <SEP> h <SEP> 6h
<tb> Ti <SEP> Ci <SEP> 121 <SEP> 185 <SEP> 196 <SEP> 202
<tb> Xi <SEP> Ci <SEP> 49 <SEP> 46 <SEP> 48 <SEP> 49
<tb> X2 <SEP> C2 <SEP> 28 <SEP> 14 <SEP> 9 <SEP> 16
<tb> X3 <SEP> C3 <SEP> 30 <SEP> 28 <SEP> 23 <SEP> 27
<tb> X4 <SEP> C4 <SEP> 18 <SEP> 16 <SEP> 11 <SEP> 11
<tb> Xs <SEP> Cs <SEP> 35 <SEP> 32 <SEP> 38 <SEP> 35
<tb> X6 <SEP> C6 <SEP> 23 <SEP> 20 <SEP> 17 <SEP> 22
<Tb>

After two hours of operation, these results confirm that the higher the pore size of the catalyst, the lower the sulfur content of the treated hydrocarbons. It is furthermore noted that the activity of the catalyst increases, when it consists of a supported metal oxide. On the other hand, after 24 hours, whatever the catalyst, there is a slight increase in the sulfur content of the desulfurized hydrocarbons, which may correspond to the beginning of clogging of the pores of the catalyst, part of the sulphones being deposited therein. .

 By this process, it is clear that the choice of a catalyst for the process of the invention is the result of a compromise between the nature of the catalyst, its specific surface area and the pore size thereof.

EXAMPLE II
In this Example, the efficiency of the catalyst is measured as a function of the oxidation of the compounds.

 The procedure is as in Example I, with the catalysts Ci-Ce and the formation of sulfone with respect to the compounds is followed.

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dibenzothiophènes, notamment le benzothiophène (BT), le dibenzothiophène (DBT) et le 4, 6 diméthyldibenzothiophène (DMBT), par chromatographie gazeuse équippée d'un détecteur spécifique de soufre (méthode SIEVERS).

dibenzothiophenes, in particular benzothiophene (BT), dibenzothiophene (DBT) and 4,6-dimethyldibenzothiophene (DMBT), by gas chromatography equipped with a specific sulfur detector (SIEVERS method).

 Table III below summarizes the results obtained.

TABLE III

<Tb>
<tb> Catalyst <SEP> Concentration <SEP>% <SEP> Oxidation <SEP> into <SEP> Sulfone
<tb> oxidant <SEP> (eqS) <SEP> BT <SEP> DBT <SEP> DMBT
<tb> CI <SEP> 3 <SEP> 80 <SEP> 78 <SEP> 81
<tb> C2 <SEP> 3 <SEP> 90 <SEP> 95 <SEP> 93
<tb> C3 <SEP> 3 <SEP> 88 <SEP> 92 <SEP> 89
<tb> C4 <SEP> 3 <SEP> 96 <SEP> 99 <SEP> 95
<tb> C5 <SEP> 3 <SEP> 85 <SEP> 87 <SEP> 88
<tb> C6 <SEP> 3 <SEP> 92 <SEP> 94 <SEP> 93
<Tb>

These results show that at least 80% conversion of the refractory thiophene derivatives to sulfones, with catalysts consisting of the sole support, and of more than 90%, with catalysts consisting of supports and at least one metal. in the form of metal oxide inserted into the support network or deposited on the support.

Claims (21)

 sulfur compounds, in an organic medium, at a temperature of at least 40 ° C., in the presence of an organic oxidant of the peroxide and peracid family and in the presence of a specific surface catalyst of greater than 100 m 2 / g and porosity ranging from 0.2 to 4 ml / g, and optionally a regeneration step of the catalyst.

1-Process for the selective desulphurization of thiophene derivatives contained in hydrocarbons from the distillation of crude oil, refined or not, consisting in oxidizing the thiophene sulfur atoms to sulfones in the presence of an oxidizing agent and in separating the sulphonated compounds from so-called hydrocarbons, this process being characterized in that it comprises at least one oxidation step by heterogeneous catalysis of  2-Process according to claim 1, characterized in that the first step is the oxidation step and the second step is the regeneration step.  3-Process according to one of claims 1 and 2, characterized in that the two steps are carried out successively in the same reactor.  4-Process according to one of claims 1 and 2, characterized in that the two steps are performed simultaneously in two reactors (1,2) arranged in parallel and operating alternately for one and the other of the steps.  5-Process according to one of claims 1 and 2, characterized in that the two steps are carried out in two reactors movable beds (20a, 20b) connected to each other by the catalyst bed, one being dedicated to oxidation, the other to regeneration.  6-Process according to one of claims 1 to 5, characterized in that the oxidizing agent is selected from the group consisting of organic peroxides, organic hydroperoxides and peracids.  7-Process according to one of claims 1 to 3 characterized in that the catalyst comprises a support selected from the group consisting of silicas, aluminas, zircons, amorphous or crystalline aluminosilicates, aluminophosphates, mesoporous solids, active carbons and clays.  8-Process according to claim 7, characterized in that the catalyst contains at least one metal selected from the group consisting of titanium, zirconium, vanadium, chromium, molybdenum, iron, <Desc / Clms Page number 15>  manganese and tungsten, this metal being introduced into the support network or deposited as an oxide on the support.

 9-Process according to claims 1 to 8, characterized in that the catalyst contains from 0 to 30% by weight and preferably from 0 to 20% by weight of metal in oxide form.  10-Process according to one of claims 1 to 9 characterized in that the catalyst consists of at least one support selected from gamma alumina, silica and silicic and silicoaluminated mesoporous solids.  11-Process according to one of claims 1 to 10, characterized in that the supported catalyst is selected from catalysts containing tungsten on a support selected from silicas and aluminas, alone or in admixture.  12-Process according to one of claims 1 to 11, characterized in that the oxidative molar ratio / total sulfur in the hydrocarbons ranges from 2 to 20, and preferably from 2 to 6.  13-Process according to one of claims 1 to 12, characterized in

 the oxidant is a compound of the general formula R 1 OOR 2, wherein R 1 and R 2 are chosen to be identical or different from the group consisting of hydrogen atom and linear or branched alkyl groups comprising from 1 to 30 carbon atoms; carbon, Ri and R2 can not be simultaneously hydrogen.  14-Process according to claim 13, characterized in that the oxidant is selected from the group consisting of tertiobutyl hydroperoxide and ditertiobutyl peroxide.  15-Process according to one of claims 1 to 14, characterized in that the oxidant is a peracid of formula R3COOOH, wherein R3 is hydrogen or a linear or branched alkyl group comprising from 1 to 30 carbon atoms.  16-Process according to claim 15, characterized in that the oxidant is selected from the group consisting of peracetic acid, performic acid and perbenzoic acid.  17-Process according to one of claims 1 to 16, characterized in that the regeneration step of the catalyst consists in removing the deposits formed by washing or by combustion.  18-Device for implementing the method according to one of claims 1 to 17, this device comprising at least a first <Desc / Clms Page number 16>  reactor containing an oxidation catalyst and having hydrocarbon and oxidant supply lines and an outlet pipe for the desulphurized hydrocarbons, and optionally a second reactor comprising solvent inlet lines or oxidizing gas of the catalyst, in order to regenerate it, and a flue gas outlet pipe.

 19-Device according to claim 18, characterized in that it comprises two fixed bed reactors (1,2) comprising common means for introducing effluent into the reactor and a distribution circuit of the hydrocarbon streams, oxidants and regeneration effluents of one or the other of the reactors, according to the mode of operation in oxidation or in regeneration thereof.  20-Device according to claim 18, characterized in that it comprises at least two movable bed reactors (20a, 20b) arranged in series, one operating in oxidation mode the other in regeneration mode, and a circulation loop catalyst reducing the regenerated catalyst to the oxidation reactor.  21-Application of the method according to one of claims 1 to 17 for the desulphurization of hydrotreated gas oils, kerosines and gasolines, including gasoline from catalytic cracking.