EP3898900A1

EP3898900A1 - Process for the hydrodesulfurization of sulfur-containing olefinic gasoline cuts using a regenerated catalyst having an organic compound

Info

Publication number: EP3898900A1
Application number: EP19813885.1A
Authority: EP
Inventors: Elodie Devers; Etienne Girard; Philibert Leflaive
Original assignee: IFP Energies Nouvelles IFPEN
Current assignee: IFP Energies Nouvelles IFPEN
Priority date: 2018-12-18
Filing date: 2019-12-10
Publication date: 2021-10-27
Also published as: CN113272409A; FR3090006B1; FR3090006A1; WO2020126678A1; US11773337B2; KR20210102255A; US20220056348A1; BR112021008301A2

Abstract

The invention relates to a process for the hydrodesulfurization of a sulfur-containing olefinic gasoline cut, wherein said gasoline cut is brought into contact with hydrogen and a regenerated catalyst, said hydrodesulfurization process being carried out at a temperature of between 200 and 400 °C, a total pressure of between 1 and 3 MPa, a hourly volumetric velocity, defined as being the volume flow of filler added to the volume of catalyst, of between 1 and 10 h^-1, and a hydrogen/gasoline volume ratio of between 100 and 1200 NL/L, said regenerated catalyst being formed by a hydrotreatment process and comprising at least one metal from group VIIl, at least one metal from group VIB, an oxide support and at least one organic compound containing oxygen and/or nitrogen and/or sulfur.

Description

PROCESS FOR HYDRODESULFURIZATION OF SULFUR OLEFINIC ESSENCE CUTS USING A REJUVENE CATALYST

TO AN ORGANIC COMPOUND

Field of the invention

The present invention relates to a process for hydrodesulfurization of a gasoline cut using a rejuvenated catalyst.

State of the art

Sulfur is a naturally occurring element in crude oil and is therefore present in gasoline and diesel if it is not removed during refining. Sulfur in gasoline affects the efficiency of emission reduction systems (catalytic converters) and contributes to air pollution. In order to fight against environmental pollution, all countries are gradually adopting strict sulfur specifications, the specifications being, for example, 10 ppm (weight) of sulfur in commercial species in Europe, China, United States and in Japan. The problem of reducing sulfur contents essentially focuses on gasolines obtained by cracking, whether it is catalytic (FCC Fluid Catalytic Cracking according to English terminology) or non-catalytic (coking, visbreaking, steam cracking), main sulfur precursors in petrol pools.

A solution, well known to those skilled in the art, for reducing the sulfur content consists in carrying out a hydrotreatment (or hydrodesulfurization) of the hydrocarbon cuts (and in particular essences of catalytic cracking) in the presence of hydrogen and a heterogeneous catalyst . However, this process has the major drawback of causing a very significant drop in the octane number if the catalyst used is not selective enough. This reduction in the octane number is notably linked to the hydrogenation of olefins present in this type of gasoline concomitantly with hydrodesulfurization. Unlike other hydrotreatment processes, in particular those for diesel-type fillers, the hydrodesulfurization of gasolines must therefore make it possible to respond to a double antagonistic constraint: ensuring deep hydrodesulfurization of gasolines and limiting the hydrogenation of the unsaturated compounds present.

The most used way to answer the double problem mentioned above consists in employing processes whose sequence of unit steps allows both to maximize hydrodesulfurization while limiting the hydrogenation of olefins. Thus, the most recent processes, such as the Prime G + process (trade mark), make it possible to desulfurize cracked gasolines rich in olefins, while limiting the hydrogenation of mono-olefins and consequently the loss of octane and the high hydrogen consumption resulting therefrom. Such methods are for example described in patent applications EP 1 077 247 and EP 1 174 485.

Obtaining the desired reaction selectivity (ratio between hydrodesulfurization and hydrogenation of olefins) may therefore be partly due to the choice of process, but in all cases the use of an intrinsically selective catalytic system is very often a key factor. In general, the catalysts used for this type of application are sulfide type catalysts containing an element of group VI B (Cr, Mo, W) and an element of group VIII (Fe, Ru, Os, Co, Rh, Ir, Pd, Ni, Pt). Thus in US patent 5,985,136, it is claimed that a catalyst having a surface concentration of between 0.5 × 10 -4 and 3.10 -4 gMo03 / m ² makes it possible to achieve high selectivities in hydrodesulfurization (93% of hydrodesulfurization (H DS) against 33% hydrogenation of olefins (H DO)). Furthermore, according to US Patents 4,140,626 and US 4,774,220, it may be advantageous to add a dopant (alkaline, alkaline earth) to the conventional sulfide phase (CoMoS) in order to limit the hydrogenation of olefins . Also known in the prior art are documents US 8,637,423 and EP 1,892,039 which describe selective hydrodesulfurization catalysts. When used for the hydrotreatment of an petroleum cut, a hydrotreatment catalyst sees its activity decrease due to the deposition of coke and / or sulfur-containing compounds or containing other heteroelements. It is therefore necessary to replace it after a certain period. In particular, the tightening of sulfur specifications for fuels leads to an increase in the frequency of replacement of the catalyst, which leads to an increase in the cost associated with the catalyst and an increase in the amount of spent catalyst.

To combat these drawbacks, the regeneration (gentle calcination) of hydrodesulfurization catalysts for middle distillates (diesel) or used residues is an economically and ecologically advantageous process because it allows these catalysts to be used again in industrial units rather than to landfill or recycle them (recovery of metals). However, the regenerated catalysts are generally less active than the starting solids. Thus, patent application US201 1/0079542 indicates that after regeneration, a typical distillate hydrotreating catalyst, commercially available, can have a reactivity of approximately 75% to approximately 90% of the activity of the fresh catalyst. corresponding.

To remedy this problem, these regenerated catalysts are generally additivated by various organic agents (so-called “rejuvenation” step) in the field of middle distillates. Numerous patents such as, for example, US 7,906,447, US 8,722,558, US 7,956,000, US 7,820,579 and also CN102463127 thus propose different methods for carrying out the rejuvenation of the catalysts for hydrotreating middle distillates. Middle distillate hydrodesulfurization catalysts, which have high metal contents compared to gasoline selective hydrodesulfurization catalysts, experience significant sintering during use and regeneration. Thus, the rejuvenation treatments focus on the dissolution and redistribution of the metal phases in order to recover a dispersion close to the fresh catalyst and therefore an activity close to the fresh catalyst.

The gasoline selective hydrodesulfurization catalysts present different regeneration problems from the diesel hydrotreatment catalysts, in particular because of the need to maintain the selective nature of the catalyst with respect to hydrodesulfurization and hydrogenation reactions. olefins. Indeed, an increase in selectivity is generally more sought after than an increase or maintenance of activity in the field of essences. As regards the selective hydrodesulfurization of gasolines, if conventional regeneration is possible, the skilled person expects, taking into account what has been demonstrated for the hydrotreatment catalysts of distillais means, that the catalyst has a significantly lower activity than that of fresh catalyst and with a potentially decreased selectivity, due to the changes in structure of the active phase supported on the catalyst during regeneration. Such a rejuvenation process is described for a selective hydrodesulfurization catalyst for FCC gasolines used in patent CN 105642312. This complex process uses, in addition to an organic agent, one or more metallic additives containing at least one element chosen from Na , K, Mg, Ca, Cu and Zn; and a heat treatment with an atmosphere with a controlled oxygen content. There is therefore still today a keen interest in refiners for hydrodesulfurization processes, in particular gasoline cuts which have good catalytic performance, in particular in terms of catalytic activity in hydrodesulfurization and of selectivity, allowing the use of catalysts. from spent hydrotreatment catalysts. Objects of the invention

The invention therefore relates to a process for hydrodesulfurization of an olefinic gasoline cut containing sulfur in which said gasoline cut is brought into contact with hydrogen and a rejuvenated catalyst, said hydrodesulfurization process being carried out at a temperature between 200 and 400 ° C, a total pressure between 1 and 3 MPa, an hourly volume speed, defined as the volume flow rate of feed relative to the volume of catalyst, between 1 and 10 h ¹ , and a hydrogen / feed volume ratio gasoline between 100 and 1200 NL / L, said rejuvenated catalyst resulting from a hydrotreatment process and comprises at least one metal from group VIII, at least one metal from group VI B, an oxide support and at least one organic compound containing oxygen and / or nitrogen and / or sulfur.

It has in fact been observed that the use of a catalyst rejuvenated with an organic compound in a process for the selective hydrodesulfurization of gasolines only causes a very small loss of activity compared to the use of the same fresh catalyst. and induced so surprisingly an improvement in selectivity. Without being bound to any theory, it seems that the changes in the active phase caused by the rejuvenation of the catalyst and inducing a better selectivity towards the hydrodesulfurization reaction of the active sites make it possible to compensate for the reduction in the number of these sites and thus maintain the activity of the catalyst.

According to a variant, the organic compound containing oxygen and / or nitrogen and / or sulfur is chosen from a compound comprising one or more chemical functions chosen from a carboxylic function, alcohol, thiol, thioether, sulfone, sulfoxide , ether, aldehyde, ketone, ester, carbonate, amine, nitrile, imide, oxime, urea, amide or the compounds including a furan cycle or sugars.

According to a variant, the organic compound containing oxygen and / or nitrogen and / or sulfur is chosen from g-valerolactone, 2-acetylbutyrolactone, triethylene glycol, diethylene glycol, ethylene glycol, acid ethylenediaminetetraacetic acid, maleic acid, malonic acid, citric acid, gluconic acid, a C1-C4 dialkyl succinate, glucose, fructose, sucrose, sorbitol, xylitol, acid g-ketovaleric, dimethylformamide, 1-methyl-2-pyrrolidinone, propylene carbonate, 2-methoxyethyl 3-oxobutanoate, bicine, tricine, 2-furaldehyde, 5-hydroxymethylfurfural, 2-acetylfuran , 5-methyl-2-furaldehyde, ascorbic acid, butyl lactate, ethyl 3-hydroxybutanoate, ethyl 3-ethoxypropanoate, 2-ethoxyethyl acetate, 2- acetate butoxyethyl, 2-hydroxyethyl acrylate, 1-vinyl-2-pyrrolidinone, 1, 3-dimethyl-2-imidazolidinone, 1- (2-hydroxyethyl) -2-pyrrolidinone, 1- (2-h ydroxyethyl) -2,5-pyrrolidinedione, 5-methyl-2 (3H) -furanone, 1-methyl-2-piperidinone and 4-aminobutanoic acid.

According to a variant, the rejuvenated catalyst has a group VI B metal content of between 1 and 40% by weight of oxide of said group VI B metal relative to the total weight of the rejuvenated catalyst and a group VIII metal content of between 0.1 and 10% by weight of oxide of said group VIII metal relative to the total weight of the rejuvenated catalyst. According to a variant, the rejuvenated catalyst also contains phosphorus, the phosphorus content being between 0.3 and 10% by weight expressed as P2O5 relative to the total weight of the rejuvenated catalyst and the phosphorus / (metal of group VIB) molar ratio in the regenerated catalyst is between 0.1 and 0.7. According to a variant, the rejuvenated catalyst is characterized by a specific surface of between 20 and 200 m ² / g, preferably between 30 and 180 m ² / g.

According to a variant, the oxide support of the rejuvenated catalyst is chosen from aluminas, silica, silica alumina or alternatively titanium or magnesium oxides used alone or as a mixture with alumina or silica alumina. According to a variant, the rejuvenated catalyst contains residual carbon at a content of less than 2% by weight relative to the total weight of the rejuvenated catalyst.

According to one variant, the rejuvenated catalyst contains contains residual sulfur at a content of less than 5% by weight relative to the total weight of the rejuvenated catalyst.

Alternatively, the rejuvenated catalyst is subjected to a sulfurization step before or during the hydrodesulfurization process.

Alternatively, the gasoline cut is a gasoline from a catalytic cracking unit.

According to a variant, the process is carried out in a catalytic bed of a reactor of the fixed bed type containing several catalytic beds, at least one other catalytic bed upstream or downstream of the catalytic bed containing the rejuvenated catalyst in the direction of circulation of the charge contains at least partly a fresh catalyst and / or a regenerated catalyst.

According to a variant, the process is carried out in at least two reactors in series of the fixed bed type or of the bubbling bed type, at least one of the reactors contains a rejuvenated catalyst while another reactor contains a fresh catalyst or a regenerated catalyst, or a mixture of a rejuvenated catalyst and a fresh and / or regenerated catalyst, and this in any order, with or without removal of at least part of the hhS from the effluent from the first reactor before treating said effluent in the second reactor. In the following, groups of chemical elements are given according to CAS Classification (CRC Handbook of Chemistry and Physics, CRC press publisher, editor DR Lide, 81 ^th Edition, 2000-2001). For example, group VIII according to the CAS classification corresponds to the metals in columns 8, 9 and 10 according to the new IUPAC classification. Description of the invention

The hydrodesulfurization process according to the invention makes it possible to transform the organo-sulfur compounds of a gasoline fraction into hydrogen sulfide (H2S) while limiting as much as possible the hydrogenation of the olefins present in said fraction.

Load to be processed

The method according to the invention makes it possible to treat any type of olefinic gasoline cut containing sulfur, such as for example a cut resulting from a coking unit (coking according to English terminology), visbreaking (visbreaking according to English terminology -saxonne), steam cracking (steam cracking according to Anglo-Saxon terminology) or catalytic cracking (FCC, Fluid Catalytic Cracking according to Anglo-Saxon terminology). This gasoline can optionally be composed of a significant fraction of gasoline from other production processes such as atmospheric distillation (gasoline from direct distillation (or straight run gasoline according to English terminology) or from conversion (essence of coking or steam cracking). Said charge preferably consists of a gasoline cut from a catalytic cracking unit.

The feedstock is an olefinic petroleum cut containing sulfur, the range of boiling points typically extending from the boiling points of hydrocarbons with 2 or 3 carbon atoms (C2 or C3) up to 260 ° C, preferably from the boiling points of hydrocarbons with 2 or 3 carbon atoms (C2 or C3) up to 220 ° C, more preferably from the boiling points of hydrocarbons with 5 carbon atoms up to 220 ° vs. The method according to the invention can also treat loads having end points lower than those mentioned above, such as for example a C5-180 ° C cut.

The sulfur content of gasoline cuts produced by catalytic cracking (FCC) depends on the sulfur content of the feed treated by the FCC, on the presence or not of a pretreatment of the feed of the FCC, as well as on the end point of the chopped off. Generally, the sulfur contents of an entire gasoline cut, in particular those originating from the FCC, are greater than 100 ppm by weight and most of the time greater than 500 ppm by weight. For gasolines having end points greater than 200 ° C., the sulfur contents are often greater than 1000 ppm by weight, they can even in certain cases reach values of the order of 4000 to 5000 ppm by weight.

In addition, gasolines from catalytic cracking units (FCC) contain, on average, between 0.5% and 5% by weight of diolefins, between 20% and 50% by weight of olefins, between 10 ppm and 0.5% weight of sulfur of which generally less than 300 ppm of mercaptans. Mercaptans are generally concentrated in the light fractions of petrol and more precisely in the fraction whose boiling temperature is below 120 ° C.

It should be noted that the sulfur compounds present in gasoline can also include heterocyclic sulfur compounds, such as for example thiophenes, alkylthiophenes or benzothiophenes. These heterocyclic compounds, unlike mercaptans, cannot be removed by the extractive processes. These compounds sulfur are therefore eliminated by hydrotreatment, which leads to their transformation into hydrocarbons and H2S.

Preferably, the gasoline treated by the process according to the invention is a heavy gasoline (or HCN for Heavy Cracked Naphtha according to English terminology) resulting from a distillation step aiming to separate a wide section from the gasoline obtained a cracking process (or FRCN for Full Range Cracked Naphtha according to English terminology) into a light essence (LCN for Light Cracked Naphtha according to Anglo-Saxon terminology) and a heavy essence FICN. The cutting point of light petrol and heavy petrol is determined in order to limit the sulfur content of the light petrol and to allow its use in the petrol pool preferably without additional post-treatment. Advantageously, the large cut FRCN is subjected to a selective hydrogenation step described below before the distillation step.

The rejuvenated catalyst

The rejuvenated catalyst is derived from an at least partially spent catalyst, itself derived from a fresh catalyst, which has been used in a hydrotreatment process for a certain period of time and which has an activity which is substantially lower than that of the fresh catalyst which requires its replacement. The at least partially spent catalyst is firstly regenerated, then rejuvenated by adding at least one organic compound containing oxygen and / or nitrogen and / or sulfur, then dried. The rejuvenated catalyst can come from a hydrotreatment of any petroleum cut, such as a naphtha, kerosene, diesel cut, vacuum distillate or residue. The term “hydrotreatment” means reactions including in particular hydrodesulfurization (H DS), hydrodenitrogenation (HDN) and hydrogenation of aromatics (HDA). It can also come from a hydro-treatment of biomass or bio-oils. Preferably, the rejuvenated catalyst results from a hydrodesulfurization process of an olefinic gasoline fraction containing sulfur carried out under the conditions as described below. The rejuvenated catalyst comprises at least one group VIII metal, at least one group VI B metal, an oxide support and an organic compound containing oxygen and / or nitrogen and / or sulfur as described below, and optionally phosphorus. According to another variant, the rejuvenated catalyst does not comprise phosphorus.

The metal of group VI B present in the active phase of the rejuvenated catalyst is preferably chosen from molybdenum and tungsten. The group VIII metal present in the active phase of the rejuvenated catalyst is preferably chosen from cobalt, nickel and the mixture of these two elements. The active phase of the rejuvenated catalyst is preferably chosen from the group formed by the combination of the elements nickel-molybdenum, cobalt-molybdenum and nickel-cobalt-molybdenum and very preferably the active phase consists of cobalt and molybdenum.

The group VIII metal content is between 0.1 and 10% by weight of group VIII metal oxide relative to the total weight of the rejuvenated catalyst, preferably between 0.6 and 8% by weight, preferably between 2 and 7%, very preferably between 2 and 6% by weight and even more preferably between 2.5 and 6% by weight.

The content of group VI B metal is between 1 and 40% by weight of oxide of group VI B metal relative to the total weight of the rejuvenated catalyst, preferably between 1 and 25% by weight, very preferably between 2 and 18% by weight.

The molar ratio of group VIII metal to group VIB metal of the rejuvenated catalyst is generally between 0.1 and 0.8, preferably between 0.2 and 0.6.

In addition, the rejuvenated catalyst has a density of group VIB metal, expressed in number of atoms of said metal per unit area of the rejuvenated catalyst, which is between 0.5 and 30 atoms of group VIB metal per nm ² of rejuvenated catalyst, preferably between 2 and 25, and even more preferably between 3 and 15. The metal density of group VIB, expressed in number of atoms of metal of group VIB per unit area of the rejuvenated catalyst (number of atoms of group VIB metal per nm ² of rejuvenated catalyst) is calculated for example from the following relationship: d (group metal

with:

• X =% weight of metal from group VI B;

• N _A = Number of Avogadro equal to 6,022.10 ²³ ;

• S = specific surface area of the catalyst (m ² / g), measured according to standard ASTM D3663; · M _M = molar mass of the metal of group VIB (for example 95.94 g / mol for molybdenum).

For example, if the catalyst contains 20% by weight of molybdenum oxide M0O3 (i.e. 13.33% by weight of Mo) and has a specific surface of 100 m ² / g, the density d (Mo) is equal to :

(13.33 XN _a ) _

d (Mo) = _{(1 QQ c 10i8 x 100 x 96)} = ⁸ ′ ^{4 Mo atoms} / nrrr of catalyst Optionally, the rejuvenated catalyst can also have a phosphorus content generally between 0.3 and 10% by weight of P2O5 relative to the total weight of rejuvenated catalyst, preferably between 0.5 and 5% by weight, and very preferably between 1 and 3% by weight. Furthermore, the phosphorus / (group VIB metal) molar ratio is generally between 0.1 and 0.7, preferably between 0.2 and 0.6, when the phosphorus is present.

The contents of group VIB metal, of group VIII metal and of phosphorus in the fresh, at least partially spent, regenerated or rejuvenated catalyst are expressed as oxides after correction of the loss on ignition of the catalyst sample at 550 ° C. for two hours in a muffle oven. Loss on ignition is due to loss of moisture, carbon, sulfur and / or other contaminants. It is determined according to ASTM D7348.

Preferably, the rejuvenated catalyst is characterized by a specific surface of between 5 and 400 m ² / g, preferably between 10 and 250 m ² / g, preferably between 20 and 200 m ² / g, very preferred between 30 and 180 m ² / g. The specific surface is determined in the present invention by the BET method according to standard ASTM D3663, as described in the work Rouquerol F .; Rouquerol J .; Singh K. “Adsorption by Powders & Porous So / ids; Princip! E, methodology and applications ", Academie Press, 1999, for example using an Autopore III ™ model device from the Microméritics ™ brand.

The pore volume of the rejuvenated catalyst is generally between 0.4 cm ³ / g and 1.3 cm ³ / g, preferably between 0.6 cm ³ / g and 1.1 cm ³ / g. The total pore volume is measured by mercury porosimetry according to standard ASTM D4284 with a wetting angle of 140 °, as described in the same work.

The packed filling density (DRT) of the rejuvenated catalyst is generally between 0.4 and 0.7 g / ml, preferably between 0.45 and 0.69 g / ml. The DRT measurement consists of introducing the catalyst into a test tube whose volume has previously been determined and then, by vibration, packing it until a constant volume is obtained. The apparent density of the packed product is calculated by comparing the mass introduced and the volume occupied after packing.

The catalyst can be in the form of small diameter, cylindrical or multi-lobed extrudates (three-lobed, four-lobed, etc.), or spheres. The oxide support of the rejuvenated catalyst is usually a porous solid chosen from the group consisting of: aluminas, silica, silica alumina or alternatively titanium or magnesium oxides used alone or as a mixture with alumina or silica alumina. It is preferably chosen from the group consisting of silica, the family of transition aluminas and alumina silicas, very preferably, the support is essentially constituted by at least one transition alumina, that is to say that 'It comprises at least 51% by weight, preferably at least 60% by weight, very preferably at least 80% by weight, or even at least 90% by weight of transition alumina. It preferably consists only of a transition alumina. Preferably, the catalyst support is a “high temperature” transition alumina, that is to say which contains alumina of theta, delta, kappa or alpha phase, alone or in mixture and an amount less than 20%. alumina of gamma, chi or eta phase.

The rejuvenated catalyst also contains contaminants from the feed such as carbon, sulfur and other contaminants such as silicon, arsenic and chlorine. The rejuvenated catalyst contains residual carbon at a content preferably less than 2% by weight, preferably between 0.1% and 1.9% by weight relative to the total weight of the rejuvenated catalyst, preferably between 0.1% and 1 , 5% by weight and particularly preferably between 0.1% and 1.0% by weight. The rejuvenated catalyst may also not contain residual carbon.

Note that the term "residual carbon" in the present application means carbon (coke) remaining in the rejuvenated catalyst which was already present after regeneration of the at least partially spent catalyst. This residual carbon content in the regenerated catalyst is measured by elemental analysis according to ASTM D5373. The rejuvenated catalyst contains residual sulfur (before optional sulfurization) at a content of less than 5% by weight, preferably between 0.1% and 4.9% by weight relative to the total weight of the rejuvenated catalyst, preferably between 0, 1% and 2.0% by weight and particularly preferably between 0.2% and 0.8% by weight. The rejuvenated catalyst may also not contain residual sulfur. This residual sulfur content in the rejuvenated catalyst is measured by elemental analysis according to ASTM D5373.

Optionally, the rejuvenated catalyst may also have a low content of contaminants originating from the charge treated by the fresh catalyst from which it originates, such as silicon, arsenic or chlorine. Preferably, the silicon content (in addition to that possibly present on the fresh catalyst) is less than 2% by weight and very preferably less than 1% by weight relative to the total weight of the rejuvenated catalyst.

Preferably, the arsenic content is less than 2000 ppm by weight and very preferably less than 500 ppm by weight relative to the total weight of the rejuvenated catalyst. Preferably, the chlorine content is less than 2000 ppm by weight and very preferably less than 500 ppm by weight relative to the total weight of the rejuvenated catalyst. The rejuvenated catalyst also contains an organic compound containing oxygen and / or nitrogen and / or sulfur. Generally, the organic compound is chosen from a compound comprising one or more chemical functions chosen from a carboxylic function, alcohol, thiol, thioether, sulfone, sulfoxide, ether, aldehyde, ketone, ester, carbonate, amine, nitrile, imide, oxime, urea and amide or the compounds including a furanic cycle or the sugars.

The organic compound containing oxygen can be one or more chosen from the compounds comprising one or more chemical functions chosen from a carboxylic, alcohol, ether, aldehyde, ketone, ester or carbonate function or alternatively the compounds including a furanic cycle or sugars. For example, the organic compound containing oxygen can be one or more chosen from the group consisting of ethylene glycol, diethylene glycol, triethylene glycol, a polyethylene glycol (with a molecular weight of between 200 and 1500 g / mol), propylene glycol, 2-butoxyethanol, 2- (2- butoxyethoxy) ethanol, 2- (2-methoxyethoxy) ethanol, triethylene glycoldimethyl ether, glycerol, acetophenone, 2,4-pentanedione, pentanone, acetic acid, maleic acid, malic acid, malonic acid, oxalic acid, gluconic acid, tartaric acid, citric acid, g-ketovaleric acid, a succinate of C1-C4 dialkyl, and more particularly dimethyl succinate, methyl acetoacetate, ethyl acetoacetate, 2-methoxyethyl 3-oxobutanoate, 2-methacryloyloxyethyl 3-oxobutanoate, dibenzofuran, a crown ether , orthophthalic acid, glucose, fructose, sucrose, sorbitol, xylitol, g-valerolac tone, 2- acetylbutyrolactone, propylene carbonate, 2-furaldehyde (also known as furfural), 5-hydroxymethylfurfural (also known as 5- (hydroxymethyl) -2-furaldehyde or 5-HMF), 2-acetylfuran, 5-methyl-2-furaldehyde, methyl 2-furoate, furfuryl alcohol (also known as furfuranol), furfuryl acetate, ascorbic acid, butyl lactate, butyl butyryllactate, ethyl 3-hydroxybutanoate, ethyl 3-ethoxypropanoate, methyl 3-methoxypropanoate, 2-ethoxyethyl acetate, 2-butoxyethyl acetate, 2- acrylate hydroxyethyl, 2-hydroxyethyl methacrylate, and 5-methyl-2 (3H) -furanone. The organic compound containing nitrogen can be one or more chosen from compounds comprising one or more chemical functions chosen from an amine or nitrile function. By way of example, the organic compound containing nitrogen can be one or more chosen from the group consisting of ethylenediamine, diethylenetriamine, hexamethylenediamine, triethylenetetramine, tetraethylenepentamine, pentaethylene hexane, acetonitrile , octylamine, guanidine or a carbazole.

The organic compound containing oxygen and nitrogen may be one or more chosen from compounds comprising one or more chemical functions chosen from a carboxylic acid, alcohol, ether, aldehyde, ketone, ester, carbonate, amine function , nitrile, imide, amide, urea or oxime. By way of example, the organic compound containing oxygen and nitrogen may be one or more chosen from the group consisting of 1,2-cyclohexanediaminetetraacetic acid, monoethanolamine (MEA), 1- methyl-2-pyrrolidinone, dimethylformamide, ethylenediaminetetraacetic acid (EDTA), alanine, glycine, nitrilotriacetic acid (NTA), N- (2-hydroxyethyl) ethylenediamine-N, N ', N '-triacetic acid (HEDTA), diethylene triaminepentaacetic acid (DTPA), tetramethylurea, glutamic acid, dimethylglyoxime, bicine, tricine, 2-methoxyethyl cyanoacetate, 1-ethyl-2-pyrrolidinone, 1-vinyl-2-pyrrolidinone, 1, 3-dimethyl-2-imidazolidinone, 1- (2-hydroxyethyl) -2-pyrrolidinone, 1- (2-hydroxyethyl) -2,5-pyrrolidinedione, 1 -methyl-2-piperidinone, 1-acetyl-2-azepanone, 1-vinyl-2-azepanone and 4-aminobutanoic acid.

The sulfur-containing organic compound may be one or more chosen from compounds comprising one or more chemical functions chosen from a thiol, thioether, sulfone or sulfoxide function. For example, the sulfur-containing organic compound may be one or more chosen from the group consisting of thioglycolic acid, 2,2'-thiodiethanol, 2-hydroxy-4-methylthiobutanoic acid, a sulfonated derivative of a benzothiophene or a sulfoxidated derivative of a benzothiophene, methyl 3- (methylthio) propanoate and ethyl 3- (methylthio) propanoate.

Preferably, the organic compound contains oxygen, preferably it is chosen from g-valerolactone, 2-acetylbutyrolactone, triethylene glycol, diethylene glycol, ethylene glycol, ethylenediaminetetraacetic acid (EDTA), maleic acid, malonic acid, citric acid, gluconic acid, dimethyl succinate, glucose, fructose, sucrose, sorbitol , xylitol, g-ketovaleric acid, dimethylformamide, 1-methyl-2-pyrrolidinone, propylene carbonate, 2-methoxyethyl 3-oxobutanoate, bicine, tricine, 2-furaldehyde (also known under the name furfural), 5-hydroxymethylfurfural (also known as 5- (hydroxymethyl) -2-furaldehyde or 5-HMF), 2-acetylfuran, 5-methyl-2-furaldehyde, ascorbic acid, butyl lactate, ethyl 3-hydroxybutanoate, ethyl 3-ethoxypropanoate, 2-ethoxyethyl acetate, 2-butoxyethyl acetate, 2-hydroxyethyl acrylate, 1-vinyl- 2-pyrrolidinone, 1, 3-dimethyl-2-imidazolidinone, 1- (2-hydroxyethyl) -2-pyrrolidinone, 1- (2-hydroxyethyl) -2,5-pyrrolidinedione, 5-methyl-2 ( 3H) -furanone, 1-methyl-2-piperidinone and acid 4- aminobutanoic.

The content of organic compound (s) containing oxygen and / or nitrogen and / or sulfur on the rejuvenated catalyst is between 1 and 30% by weight, preferably between 1, 5 and 25% weight, and more preferably between 2 and 20% by weight relative to the total weight of the rejuvenated catalyst.

Process for the preparation of the rejuvenated catalyst

The rejuvenated catalyst is derived from an at least partially used catalyst, itself derived from a fresh catalyst. More particularly, the rejuvenated catalyst is prepared from an at least partially used catalyst resulting from a hydrotreatment process and preferably resulting from a hydrodesulfurization process of an olefinic gasoline fraction containing sulfur. The at least partially used catalyst comprises at least one group VIII metal, at least one group VI B metal, an oxide support, and optionally phosphorus, said rejuvenation process comprising the following steps:

a) the at least partially spent catalyst is regenerated in a flow of oxygen-containing gas at a temperature between 350 ° C. and 550 ° C. so as to obtain a regenerated catalyst,

b) at least one organic compound containing oxygen and / or nitrogen and / or sulfur is brought into contact with the regenerated catalyst, c) a drying step is carried out at a temperature below 200 ° C., without subsequent calcination, so as to obtain a rejuvenated catalyst.

It is important to emphasize that the rejuvenated catalyst during its preparation process does not undergo calcination after the introduction of the organic compound containing oxygen and / or nitrogen and / or sulfur in order to preserve at least part the organic compound in the catalyst. By calcination is meant here a heat treatment under a gas containing air or oxygen at a temperature greater than or equal to 200 ° C.

In addition, during step b) no addition of a group VIB metal compound or a group VIII metal compound or phosphorus is made to the regenerated catalyst.

The preparation of the fresh catalyst is known and generally comprises a step of impregnating the metals of group VIII and group VIB and optionally phosphorus and / or an organic compound on the oxide support, followed by drying, then optional calcination to obtain the active phase in their oxide forms. Before its use in a hydrodesulfurization process of an olefinic gasoline fraction containing sulfur, the fresh catalyst is generally subjected to sulfidation in order to form the active species as described below.

According to a variant of the invention, the fresh catalyst has not undergone calcination during its preparation, that is to say that the impregnated catalytic precursor has not been subjected to a heat treatment step at a temperature above 200 ° C under an inert atmosphere or under an oxygen-containing atmosphere, in the presence of water or not.

According to another preferred variant of the invention, the fresh catalyst has undergone a calcination step during its preparation, that is to say that the impregnated catalytic precursor has been subjected to a heat treatment step at a temperature comprised between 200 and 1000 ° C and preferably between 250 and 750 ° C, for a period typically between

15 minutes and 10 hours, under an inert atmosphere or under an atmosphere containing oxygen, in the presence of water or not. Indeed, it has been noticed that a rejuvenated catalyst resulting from a fresh catalyst having undergone a calcination stage during its preparation shows a less pronounced drop in activity than a rejuvenated catalyst originating from a fresh catalyst which has not undergone a calcination stage during its preparation.

The preparation of the rejuvenated catalyst comprises a step a) of removing coke and sulfur (regeneration step). Indeed, according to step a), the at least partially spent catalyst is regenerated in a flow of gas containing oxygen at a temperature between 350 ° C and 550 ° C so as to obtain a regenerated catalyst.

Even if this is possible, the regeneration is preferably not carried out by keeping the catalyst loaded in the hydrotreatment reactor (in situ regeneration). Preferably, the at least partially used catalyst is therefore extracted from the reactor and sent to a regeneration installation in order to perform the regeneration in said installation (ex-situ regeneration).

Step a) of regeneration is preferably preceded by a deoiling step. The deoiling step generally comprises bringing the at least partially spent catalyst into contact with a stream of inert gas (that is to say essentially free of oxygen), for example in a nitrogen atmosphere or the like. a temperature between 300 ° C and 400 ° C, preferably between 300 ° C and 350 ° C. The flow rate of inert gas in terms of flow rate per unit volume of the catalyst is 5 to 150 NL.L Lh ¹ for 3 to 7 hours.

As a variant, the deoiling step can be carried out using light hydrocarbons, by steam treatment or any other similar process.

The deoiling step makes it possible to eliminate the soluble hydrocarbons and therefore to release the porosity of the at least partially used catalyst necessary for rejuvenation.

Stage a) of regeneration is generally carried out in a flow of gas containing oxygen, generally air. The water content is generally between 0 and 50% by weight. The gas flow rate in terms of flow rate per volume unit of the at least partially spent catalyst is preferably from 20 to 2000 NL.L Lh ¹ , more preferably from 30 to 1000 NL.L Lh ¹ , and more preferably from 40 at 500 NL.L Lh ¹ . The duration of the regeneration is preferably 2 hours or more, more preferably 2.5 hours or more, and particularly preferably 3 hours or more. The regeneration of the at least partially spent catalyst is generally carried out at a temperature between 350 ° C and 550 ° C, preferably between 360 and 500 ° C.

After the regeneration step, the regenerated catalyst intended for use in the hydrodesulfurization process according to the invention is subjected to a rejuvenation step b) according to which at least one organic compound containing oxygen is brought into contact and / or nitrogen and / or sulfur as described above with the regenerated catalyst. The function of organic compounds is to increase the catalytic activity compared to non-additive catalysts. In this case, the molar ratio of the organic compound added per group VI B metal already present in the regenerated catalyst is between 0.01 to 5 mol / mol, preferably between 0.05 to 3 mol / mol, so preferred between 0.05 and 2 mol / mol and very preferably, between 0.1 and 1.5 mol / mol.

When several organic compounds are present, the different molar ratios apply for each of the organic compounds present.

Step b) of bringing said regenerated catalyst into contact with an impregnation solution containing a compound comprising an organic compound containing oxygen and / or nitrogen and / or sulfur can be carried out either by impregnation in slurry , either by excess impregnation, or by dry impregnation, or by any other means known to those skilled in the art.

Impregnation at equilibrium (or in excess), consists in immersing the support or the catalyst in a volume of solution (often considerably) greater than the pore volume of the support or of the catalyst while maintaining the system under agitation to improve the exchanges between the solution and the support or catalyst. A balance is finally reached after diffusion of the different species in the pores of the support or catalyst. Control of the quantity of elements deposited is ensured by the prior measurement of an adsorption isotherm which relates the concentration of elements to be deposited contained in the solution to the quantity of elements deposited on the solid in equilibrium with this solution. Dry impregnation consists in introducing a volume of impregnation solution equal to the pore volume of the support or of the catalyst. Dry impregnation makes it possible to deposit on a given support or catalyst all of the additives contained in the impregnation solution. Step b) can advantageously be carried out by one or more impregnation in excess of solution or preferably by one or more dry impregnation and very preferably by a single dry impregnation of said at least partially used catalyst, using of the impregnation solution.

Said organic compound is preferably impregnated on said catalyst after solubilization in aqueous solution.

Preferably, the impregnation solution consists of the solvent and of the organic compound (s).

No addition of group VIB metal compound and / or group VIII metal and / or phosphorus is made during step b) of bringing said regenerated catalyst into contact with an impregnating solution containing a compound comprising an organic compound containing oxygen and / or nitrogen and / or sulfur.

The impregnation solution can comprise any polar solvent known to a person skilled in the art. Said polar solvent used is advantageously chosen from the group formed by methanol, ethanol, water, phenol, cyclohexanol, taken alone or as a mixture. Said polar solvent can also be advantageously chosen from the group formed by propylene carbonate, DMSO (dimethylsulfoxide), N-methylpyrrolidone (N MP) or sulfolane, taken alone or as a mixture. Preferably, a polar protic solvent is used. A list of common polar solvents and their dielectric constant can be found in the book "Solvents and Solvent Effects in Organic Chemistry" C. Reichardt, Wiley-VCH, 3rd edition, 2003, pages 472-474. Very preferably, the solvent used is water or ethanol, and particularly preferably, the solvent is water. In one possible embodiment, the solvent can be absent in the impregnation solution. Advantageously, after each impregnation step, the impregnated support is left to mature. The maturation allows the impregnation solution to disperse homogeneously within the support.

Any maturation step is advantageously carried out at atmospheric pressure, in an atmosphere saturated with water and at a temperature between 17 ° C and 50 ° C, and preferably at room temperature. Generally a ripening period of between ten minutes and forty-eight hours and preferably between thirty minutes and six hours is sufficient.

After the rejuvenation step, the rejuvenated catalyst is subjected to a drying step at a temperature below 200 ° C, advantageously between 50 ° C and 180 ° C, preferably between 70 ° C and 150 ° C, so highly preferred between 75 ° C and 130 ° C.

The drying step is preferably carried out under an inert atmosphere or under an atmosphere containing oxygen. The drying step can be carried out by any technique known to those skilled in the art. It is advantageously carried out at atmospheric pressure or at reduced pressure. Preferably, this step is carried out at atmospheric pressure. It is advantageously carried out in a crossed bed using air or any other hot gas. Preferably, when the drying is carried out in a fixed bed, the gas used is either air, or an inert gas such as argon or nitrogen. Very preferably, the drying is carried out in a crossed bed in the presence of nitrogen and / or air. Preferably, the drying step has a duration of between 5 minutes and 15 hours, preferably between 30 minutes and 12 hours.

According to a first variant, the drying is carried out so as to preferably retain at least 30% by weight of the organic compound introduced during an impregnation step, preferably this amount is greater than 50% by weight and even more preferably, greater than 70% by weight, calculated on the basis of the carbon remaining on the rejuvenated catalyst.

At the end of the drying step, a rejuvenated catalyst is then obtained, which will be subjected to an optional activation step (sulfurization) for its subsequent implementation in the hydrodesulfurization process of gasolines. Before being brought into contact with the feedstock to be treated in the gasoline hydrodesulfurization process according to the invention, the rejuvenated catalyst generally undergoes a sulfurization step. The sulfurization is preferably carried out in a sulforeductive medium, that is to say in the presence of hhS and of hydrogen, in order to transform the metal oxides into sulphides such as, for example, SO 2 and CogSs. Sulfurization is carried out by injecting onto the catalyst a stream containing h ^ S and hydrogen, or else a sulfur compound capable of decomposing into H2S in the presence of the catalyst and hydrogen. Polysulfides such as dimethyldisulfide (DM DS) are hhS precursors commonly used to sulfurize catalysts. Sulfur can also come from the feed. The temperature is adjusted so that the hhS reacts with the metal oxides to form metal sulfides. This sulphurization can be carried out in situ or ex situ (inside or outside the reactor) of the reactor of the process according to the invention at temperatures between 200 ° C and 600 ° C, and more preferably between 300 ° C and 500 ° C .

The hydrodesulfurization process according to the invention consists in bringing the olefinic gasoline fraction containing sulfur into contact with the rejuvenated catalyst and hydrogen under the following conditions:

- a temperature between 200 and 400 ° C, preferably between 230 and 330 ° C

- at a total pressure between 1 and 3 MPa, preferably between 1, 5 and 2, 5 MPa

- an hourly volume speed (WH), defined as the volume flow rate of feed relative to the volume of catalyst, between 1 and 10 h ¹ , preferably between 2 and 6 fr ¹

- a hydrogen / fuel charge volume ratio of between 100 and 1200 N L / L, preferably between 150 and 400 N L / L.

The hydrodesulfurization process according to the invention is carried out in the presence of a rejuvenated catalyst. It can also be carried out in the presence of a mixture of a rejuvenated catalyst and a fresh catalyst or a regenerated catalyst. When the fresh or regenerated catalyst is present, it comprises at least one group VIII metal, at least one group VIB metal and an oxide support, and optionally phosphorus and / or an organic compound as described above .

The active phase and the support of the fresh or regenerated catalyst may or may not be identical to the active phase and the support of the rejuvenated catalyst.

The active phase and the support of the fresh catalyst may or may not be identical to the active phase and the support of the regenerated catalyst.

When the hydrodesulfurization process is carried out in the presence of a rejuvenated catalyst and a fresh or regenerated catalyst, it can be carried out in a reactor of the fixed bed type containing several catalytic beds.

In this case, and according to a first variant, a catalytic bed containing the fresh or regenerated catalyst can precede a catalytic bed containing the rejuvenated catalyst in the direction of the charge circulation.

In this case, and according to a second variant, a catalytic bed containing the rejuvenated catalyst can precede a catalytic bed containing the fresh or regenerated catalyst in the direction of the charge circulation.

In this case, and according to a third variant, a catalytic bed can contain a mixture of a rejuvenated catalyst and a fresh catalyst and / or a rejuvenated catalyst.

In these cases, the operating conditions are those described above. They are generally identical in the various catalytic beds except for the temperature which generally increases in a catalytic bed following the exothermic hydrodesulfurization reactions.

When the hydrodesulfurization process is carried out in the presence of a rejuvenated catalyst and of a fresh or regenerated catalyst in several reactors in series of the fixed bed type or of the bubbling bed type, one reactor may comprise a rejuvenated catalyst while another reactor can comprise a fresh or regenerated catalyst, or a mixture of a rejuvenated catalyst and a fresh and / or regenerated catalyst, and this in any order. We can provide a device for removing the hhS from the effluent from the first hydrodesulfurization reactor before treating said effluent in the second hydrodesulfurization reactor. In these cases, the operating conditions are those described above and may or may not be identical in the different reactors. Selective hydrogenation (optional step)

Alternatively, the gasoline cut is subjected to a selective hydrogenation step before the hydrodesulfurization process according to the invention.

Preferably, the gasoline treated by the hydrodesulfurization process according to the invention is a heavy gasoline resulting from a distillation step aiming to separate a wide cut from the gasoline resulting from a cracking process (or FRCN for Full Range Cracked Naphtha according to Anglo-Saxon terminology) in a light essence and a heavy essence.

Advantageously, the large cut FRCN is subjected to a selective hydrogenation step described below before the distillation step.

Said FRCN cut is previously treated in the presence of hydrogen and of a selective hydrogenation catalyst so as to at least partially hydrogenate the diolefins and carry out a weighting reaction for part of the mercaptan compounds (RSH) present in the feed. as thioethers, by reaction with olefins.

To this end, the large cut FRCN is sent to a selective hydrogenation catalytic reactor containing at least one fixed or mobile bed of catalyst for the selective hydrogenation of diolefins and the weighting of mercaptans. The reaction for the selective hydrogenation of diolefins and the weighting down of mercaptans is preferably carried out on a sulfur catalyst comprising at least one element from group VIII and optionally at least one element from group VIB and an oxide support. The element of group VIII is preferably chosen from nickel and cobalt and in particular nickel. The element of group VIB, when it is present, is preferably chosen from molybdenum and tungsten and very preferably molybdenum.

The catalyst oxide support is preferably chosen from alumina, nickel aluminate, silica, silicon carbide, or a mixture of these oxides. We use, so preferred, alumina and even more preferably, high purity alumina. According to a preferred embodiment, the selective hydrogenation catalyst contains nickel at a content by weight of nickel oxide (in NiO form) of between 1 and 12%, and molybdenum at a content by weight of molybdenum oxide. (in M0O3 form) of between 6% and 18% and a nickel / molybdenum molar ratio of between 0.3 and 2.5, the metals being deposited on a support consisting of alumina and the sulphurization rate of the metals constituting the catalyst being greater than 50%.

During the optional selective hydrogenation step, the gasoline is brought into contact with the catalyst at a temperature between 50 ° C and 250 ° C, and preferably between 80 ° C and 220 ° C, and again more preferred between 90 ° C and 200 ° C, with a liquid space speed (LHSV) of between 0.5 h ¹ and 20 h ¹ , the unit of the liquid space speed being the liter of feed per liter of catalyst and per hour (L / L. h). The pressure is between 0.4 MPa and 5 MPa, preferably between 0.6 and 4 MPa and even more preferably between 1 and 2 MPa. The optional selective hydrogenation step is typically carried out with a hh / gasoline charge ratio of between 2 and 100 Nm ³ of hydrogen per m ³ of charge, preferably between 3 and 30 Nm ³ of hydrogen per m ³ of charge.

Examples

Example 1 Preparation of a regenerated catalyst A (comparative)

The support for the fresh catalyst is a transition alumina with a specific surface of 140 m ² / g and a pore volume of 1.0 cm ³ / g. The fresh catalyst is prepared by dry impregnation of the support with an aqueous solution of ammonium heptamolybdate and cobalt nitrate, the volume of the solution containing the metal precursors being strictly equal to the pore volume of the support mass. The concentration of metal precursors in aqueous solution is adjusted so as to obtain the desired weight percentage of molybdenum and cobalt on the final catalyst. After dry impregnation on the support, the catalyst is left to mature for 1 h 30 in an enclosure saturated with water, air dried in an oven at 90 ° C for 12 hours and then calcined in air at 450 ° C for 2 hours. The fresh catalyst obtained after calcination has a content of 7.4% by weight of molybdenum (equivalent MOO3) and 2.0% by weight of cobalt (equivalent CoO). This catalyst has a Co / Mo atomic ratio of 0.52.

The fresh catalyst is used to desulfurize a catalytic cracking gasoline (FCC), the characteristics of which are given in Table 1. The reaction is carried out at 270 ° C. for 900 hours in a reactor of the crossed bed type under the following conditions: P = 2 MPa, WH = 4 h ¹ , H ₂ / HC = 300 liters / liters of hydrocarbon feedstock. The catalyst is treated beforehand at 350 ° C. with a feed containing 4% by weight of sulfur in the form of DM DS (dimethyldisulfide) to ensure the sulfurization of the oxide phases. The reaction takes place in an updraft in an isothermal pilot reactor.

Table 1: Characteristics of the FCC petrol cutter used for the aging of the fresh catalyst.

The spent catalyst is taken from the reactor after the hydrodesulfurization of a catalytic cracking gasoline (FCC) described above. The spent catalyst is then washed with toluene in a Soxhlet for 7 hours at 250 ° C.

The regeneration of the spent / washed catalyst is then carried out in a tubular oven in dry air at 450 ° C. for 2 hours and the regenerated catalyst A is obtained. The residual carbon content of catalyst A is zero. Example 2 - Preparation of a regenerated catalyst B (comparative)

The support for catalyst B is a transition alumina with a specific surface area of 205 m ² / g and a pore volume of 0.8 cm ³ / g. The fresh catalyst is prepared by dry impregnation of the support with an aqueous solution of molybdenum oxide, cobalt hydroxide and orthophosphoric acid, the volume of the solution containing the metal precursors being strictly equal to the pore volume of the support mass. The concentration of metal precursors in aqueous solution is adjusted so as to obtain the desired weight percentage of molybdenum, cobalt and phosphorus on the final catalyst. After dry impregnation on the support, the catalyst is left to mature for 1 h 30 in an enclosure saturated with water, air dried in an oven at 90 ° C for 12 hours and then calcined in air at 450 ° C for 2 hours.

The fresh catalyst obtained after calcination has a content of 15.2% by weight of molybdenum (equivalent M0O3), 2.9% by weight of cobalt (equivalent CoO) and 2.5% of phosphorus (equivalent P2O5). This catalyst has a Co / Mo atomic ratio of 0.37 and a P / Mo atomic ratio of 0.33.

The spent catalyst is taken from the reactor after the hydrodesulfurization of a catalytic cracking gasoline (FCC) described above. The spent catalyst is then washed with toluene in a Soxhlet for 7 hours at 250 ° C. (deoiling).

The regeneration of the spent / washed catalyst is then carried out in a tubular oven in dry air at 450 ° C. for 2 hours and the regenerated catalyst B is obtained. The residual carbon content of the regenerated catalyst B is 0.3% by weight. Example 3 Preparation of Rejuvenated Catalysts A1 and A2 by Adding Citric Acid (According to the Invention)

Catalyst A1 is prepared by dry impregnation of regenerated catalyst A with an aqueous solution of citric acid, the volume of the solution being strictly equal to the pore volume of the mass of catalyst A. The concentration of citric acid in aqueous solution is adjusted so as to obtain a molar ratio of citric acid to molybdenum already present on the regenerated catalyst A of 0.2 mol / mol. After dry impregnation on the regenerated catalyst A, the catalyst A1 is left to mature for 1 h 30 in an enclosure saturated with water, dried in air in an oven at 90 ° C. for 12 hours. The catalyst A2 is obtained in a similar manner, but using an aqueous solution of citric acid, the concentration of which is adjusted so as to obtain a molar ratio of citric acid to molybdenum already present on the regenerated catalyst A of 1.

Example 4 Preparation of a Rejuvenated Catalyst A3 by Adding Ascorbic Acid (According to the Invention) Catalyst A3 is prepared by dry impregnation of the regenerated catalyst A with an aqueous solution of ascorbic acid, the volume of the solution being strictly equal to the pore volume of the mass of the regenerated catalyst A. The concentration of ascorbic acid in aqueous solution is adjusted so as to obtain a molar ratio of ascorbic acid to molybdenum already present on the regenerated catalyst A of 0.8 mol / mol. After dry impregnation on the regenerated catalyst A, the catalyst A3 is left to mature for 1 h 30 in an enclosure saturated with water, dried in air in an oven at 120 ° C. for 12 hours.

Example 5 Preparation of a Rejuvenated Catalyst A4 by Adding Triethylene Glycol (According to the Invention)

Catalyst A4 is prepared by dry impregnation of regenerated catalyst A with an aqueous solution of triethylene glycol, the volume of the solution being strictly equal to the pore volume of the mass of regenerated catalyst A. The concentration of triethylene glycol in aqueous solution is adjusted so as to obtain a triethylene glycol molar ratio on molybdenum already present on the regenerated catalyst A of 0.6 mol / mol. After dry impregnation on the regenerated catalyst A, the catalyst A4 is left to mature for 1 h 30 in an enclosure saturated with water, dried in air in an oven at 160 ° C. for 12 hours.

Example 6 Preparation of a Rejuvenated Catalyst A5 by Additions of Citric Acid and Urea (According to the Invention)

Catalyst A5 is prepared by dry impregnation of regenerated catalyst A with an aqueous solution of citric acid and urea, the volume of the solution being strictly equal to the pore volume of the mass of regenerated catalyst A. Concentrations of citric acid and in urea in aqueous solution are adjusted so as to obtain a respective ratio of the moles of citric acid and of urea to moles of molybdenum already present on the regenerated catalyst A of 0.3 and 1.5. After dry impregnation on the regenerated catalyst A, the catalyst A5 is left to mature for 1 h 30 in an enclosure saturated with water, dried in air in an oven at 110 ° C. for 12 hours.

Example 7 Preparation of a Rejuvenated Catalyst B1 by Adding Diethanolamine (According to the Invention)

Catalyst B1 is prepared by dry impregnation of regenerated catalyst B with an aqueous diethanolamine solution, the volume of the solution being strictly equal to the pore volume of the mass of regenerated catalyst B. The concentration of diethanolamine in aqueous solution is adjusted so to obtain a diethanolamine / molybdenum molar ratio already present on the regenerated catalyst A of 2.1 mol / mol. After dry impregnation on the regenerated catalyst B, the catalyst B1 is left to mature for 1 h 30 in an enclosure saturated with water, dried in air in an oven at 110 ° C. for 12 hours.

Example 8 Preparation of a Rejuvenated Catalyst B2 by Additions of Citric Acid and of Y-Ketovaleric Acid (According to the Invention) Catalyst B2 is prepared by dry impregnation of the regenerated catalyst B with an aqueous solution of citric acid and g-ketovaleric acid, the volume of the solution being strictly equal to the pore volume of the mass of the regenerated catalyst B. concentrations of citric acid and of g-ketovaleric acid in aqueous solution are adjusted so as to obtain a respective ratio of the moles of citric acid and of y-ketovaleric acid to moles of molybdenum already present on the regenerated catalyst A of 0.5 and 0.8. After dry impregnation on the regenerated catalyst B, the catalyst B2 is left to mature for 1 h 30 in an enclosure saturated with water, dried in air in an oven at 110 ° C. for 12 hours.

Example 9 - Evaluation of the catalytic performances of catalysts A, A1, A2, A3, A4, and A5

A model charge representative of a catalytic cracking gasoline (FCC) containing 10% by weight of 2,3-dimethylbut-2-ene and 0.33% by weight of 3-methylthiophene (i.e. 1000 ppm by weight of sulfur in the charge) is used for the evaluation of the catalytic performances of the various catalysts. The solvent used is heptane.

The hydrodesulfurization reaction (H DS) is carried out in a fixed-bed reactor traversed under a total pressure of 1.5 MPa, at 210 ° C., at WH = 6 fr ¹ (WH = volume flow rate of charge / volume of catalyst ), and a H2 / feed volume ratio of 300 N l / l, in the presence of 4 mL of catalyst. Prior to the HDS reaction, the catalyst is sulfurized in situ at 350 ° C for 2 hours under a stream of hydrogen containing 15 mol% of H2S at atmospheric pressure.

Each of the catalysts is placed successively in said reactor. Samples are taken at different time intervals and are analyzed by gas chromatography in order to observe the disappearance of the reagents and the formation of the products.

The catalytic performances of the catalysts are evaluated in terms of catalytic activity and selectivity. The hydrodesulfurization activity (H DS) is expressed from the rate constant for the HDS reaction of 3-methylthiophene (kHDS), normalized by the volume of catalyst introduced and assuming order 1 kinetics with respect to to the sulfur compound. The olefin hydrogenation activity (HydO) is expressed from the rate constant of the hydrogenation reaction of 2,3-dimethylbut-2-ene, normalized by the volume of catalyst introduced and assuming kinetics of order 1 relative to the olefin.

The selectivity of the catalyst is expressed by the normalized ratio of the rate constants kHDS / kHydO. The kHDS / kHydO ratio will be higher the more selective the catalyst. The values obtained are normalized by taking catalyst A as a reference (relative H DS activity and relative selectivity equal to 100). Performance is therefore relative H DS activity and relative selectivity.

Table 2

The rejuvenated catalysts A1, A2, A3, A4 and A5 exhibit improved activities and selectivities in hydrodesulfurization compared to the hydrogenation of olefins greater than that of comparative catalyst A (regenerated).

This improvement in the selectivity of the catalysts is particularly advantageous in the case of implementation in a process for the hydrodesulfurization of gasoline containing olefins for which it is sought to limit as much as possible the loss of octane due to the hydrogenation of the olefins.

Example 10 - Evaluation of the catalytic performances of catalysts B, B1 and B2

Catalysts B (comparative), B1 and B2 (according to the invention) are tested under the conditions described in Example 9 above. Table 3

The rejuvenated catalysts B1 and B2 have improved hydrodesulfurization activities and selectivities compared to the hydrogenation of olefins greater than that of comparative catalyst B (regenerated). This improvement in the selectivity of the catalysts is particularly advantageous in the case of implementation in a process for the hydrodesulfurization of gasoline containing olefins for which it is sought to limit as much as possible the loss of octane due to the hydrogenation of the olefins.

Example 1 1 - Preparation of a regenerated catalyst C (comparative) The support for the fresh catalyst is a transition alumina with a specific surface 140 m ² / g and a pore volume of 1.0 cm ³ / g. The fresh catalyst is prepared by dry impregnation of the support with an aqueous solution of ammonium heptamolybdate and cobalt nitrate, the volume of the solution containing the metal precursors being strictly equal to the pore volume of the support mass. The concentration of metal precursors in aqueous solution is adjusted so as to obtain the desired weight percentage of molybdenum and cobalt on the final catalyst. After dry impregnation on the support, the catalyst is left to mature for 1 h 30 in an enclosure saturated with water, air dried in an oven at 90 ° C for 12 hours and then calcined in air at 450 ° C for 2 hours.

The fresh catalyst obtained after calcination has a content of 10.4% by weight of molybdenum (equivalent MOO3) and 3.1% by weight of cobalt (equivalent CoO). This catalyst has a Co / Mo atomic ratio of 0.57. The fresh catalyst is used to desulfurize a catalytic cracking gasoline (FCC), the characteristics of which are given in Table 1. The reaction is carried out at 270 ° C. for 900 hours in a reactor of the crossed bed type under the following conditions: P = 2 MPa, WH = 4 h ¹ , H ₂ / HC = 300 liters / liters of hydrocarbon feedstock. The catalyst is treated beforehand at 350 ° C. with a feed containing 4% by weight of sulfur in the form of DM DS (dimethyldisulfide) to ensure the sulfurization of the oxide phases. The reaction takes place in an updraft in an isothermal pilot reactor.

Table 4

The regeneration of the spent / washed catalyst is then carried out in a tubular oven in dry air at 450 ° C. for 2 hours and the regenerated catalyst C. is obtained. Example 12- Preparation of rejuvenated catalysts C1 and C2 by adding citric acid (according to l 'invention)

Catalyst C1 is prepared by dry impregnation of regenerated catalyst C with an aqueous solution of citric acid, the volume of the solution being strictly equal to pore volume of the mass of catalyst C. The concentration of citric acid in aqueous solution is adjusted so as to obtain a molar ratio of citric acid to molybdenum already present on the regenerated catalyst C of 0.3 mol / mol. After dry impregnation on the regenerated catalyst C, the catalyst C1 is left to mature for 1 h 30 in an enclosure saturated with water, dried in air in an oven at 90 ° C. for 12 hours. Catalyst C1 has a specific surface of 127 m ² / g and a volume of 0.86 cm ³ / g. The residual carbon and sulfur contents of catalyst C1 are 0.16 wt% and 0.59 wt% respectively.

Catalyst C2 is obtained in a similar manner, but using an aqueous solution of citric acid, the concentration of which is adjusted so as to obtain a molar ratio of citric acid to molybdenum already present on the regenerated catalyst C of 0.9. Catalyst C2 has a specific surface of 130 m ² / g and a volume of 0.86 cm ³ / g. The residual carbon and sulfur contents of catalyst C2 are 0.19 wt% and 0.58 wt% respectively. Example 13 - Preparation of a rejuvenated catalyst C3 by adding ascorbic acid (according to the invention)

Catalyst C3 is prepared by dry impregnation of regenerated catalyst C with an aqueous solution of ascorbic acid, the volume of the solution being strictly equal to the pore volume of the mass of regenerated catalyst C. The concentration of ascorbic acid in aqueous solution is adjusted so as to obtain an ascorbic acid to molybdenum molar ratio already present on the regenerated catalyst C of 0.5 mol / mol. After dry impregnation on the regenerated catalyst C, the catalyst C3 is left to mature for 1 h 30 in an enclosure saturated with water, dried in air in an oven at 120 ° C. for 12 hours. Catalyst C3 has a specific surface of 127 m ² / g and a volume of 0.86 cm ³ / g. The residual carbon and sulfur contents of catalyst C3 are 0.17 wt% and 0.59 wt% respectively. Example 14 Preparation of a C4 Rejuvenated Catalyst by Adding Triethylene Glycol (According to the Invention)

Catalyst C4 is prepared by dry impregnation of regenerated catalyst C with an aqueous solution of triethylene glycol, the volume of the solution being strictly equal to the pore volume of the mass of regenerated catalyst C. The concentration of triethylene glycol in aqueous solution is adjusted so as to obtain a triethylene glycol to molybdenum molar ratio already present on the regenerated catalyst C of 0.6 mol / mol. After dry impregnation on the regenerated catalyst C, the catalyst C4 is left to mature for 1 h 30 in an enclosure saturated with water, dried in air in an oven at 140 ° C. for 12 hours.

Catalyst C4 has a specific surface of 126 m ² / g and a volume of 0.86 cm ³ / g. The residual carbon and sulfur contents of catalyst C4 are 0.16 wt% and 0.57 wt% respectively.

Example 15 Preparation of a C5 Rejuvenated Catalyst by Adding Citric Acid and Urea (According to the Invention)

Catalyst C5 is prepared by dry impregnation of regenerated catalyst C with an aqueous solution of citric acid and urea, the volume of the solution being strictly equal to the pore volume of the mass of regenerated catalyst C. Concentrations of citric acid and in urea in aqueous solution are adjusted so as to obtain a respective ratio of the moles of citric acid and of urea to moles of molybdenum already present on the regenerated catalyst C of 0.2 and 1.25. After dry impregnation on the regenerated catalyst C, the catalyst C5 is left to mature for 1 h 30 in an enclosure saturated with water, dried in air in an oven at 110 ° C. for 12 hours.

Catalyst C5 has a specific surface of 127 m ² / g and a volume of 0.87 cm ³ / g. The residual carbon and sulfur contents of catalyst C5 are 0.14 wt% and 0.59 wt% respectively. Example 16 - Evaluation of the catalytic performances of catalysts C, C1, C2, C3, C4 and C5

Catalysts C (comparative), C1 and C2 (according to the invention) are tested under the conditions described in Example 9 above. Table 5

The rejuvenated catalysts C1, C2, C3, C4 and C5 exhibit improved activities and selectivities in hydrodesulfurization compared to the hydrogenation of olefins greater than that of comparative catalyst C (regenerated).

Claims

1. Process for hydrodesulfurization of an olefinic gasoline cut containing sulfur in which said gasoline cut is brought into contact with hydrogen and a rejuvenated catalyst, said hydrodesulfurization process being carried out at a temperature between 200 and 400 ° C, a total pressure between 1 and 3 MPa, an hourly volume speed, defined as the volume flow rate of charge relative to the volume of catalyst, between 1 and 10 h ¹ , and a hydrogen / gasoline volume ratio between 100 and 1200 NL / L, said rejuvenated catalyst resulting from a hydrotreatment process and comprises at least one group VIII metal, at least one group VIB metal, an oxide support and at least one organic compound containing 1 oxygen and / or nitrogen and / or sulfur.

2. Method according to the preceding claim, in which the organic compound containing oxygen and / or nitrogen and / or sulfur is chosen from a compound comprising one or more chemical functions chosen from a carboxylic, alcohol, thiol function , thioether, sulfone, sulfoxide, ether, aldehyde, ketone, ester, carbonate, amine, nitrile, imide, oxime, urea, amide or the compounds including a furanic cycle or sugars.

3. Method according to one of the preceding claims, in which the organic compound containing oxygen and / or nitrogen and / or sulfur is chosen from γ-valerolactone, 2-acetylbutyrolactone, triethylene glycol, diethylene glycol, ethylene glycol, ethylenediaminetetraacetic acid, maleic acid, malonic acid, citric acid, gluconic acid, a C1-C4 dialkyl succinate, glucose, fructose, sucrose, sorbitol, xylitol, g-ketovaleric acid, dimethylformamide, 1-methyl-2-pyrrolidinone, propylene carbonate, 2-methoxyethyl 3-oxobutanoate, bicine, tricine, 2-furaldehyde, 5-hydroxymethylfurfural, 2-acetylfuran, 5-methyl-2-furaldehyde, ascorbic acid, butyl lactate, ethyl 3-hydroxybutanoate, ethyl 3-ethoxypropanoate, acetate 2 -ethoxyethyl, 2-butoxyethyl acetate, 2-hydroxyethyl acrylate, 1-vinyl-2-pyrrolidinone, 1, 3-dimethyl-2-imidazolidinone, 1- (2-hydroxyethyl) -2- pyrrolidinone, 1- (2-hydroxyethyl) -2,5-pyrrolidinedione, 5- methyl-2 (3H) -furanone, 1-methyl-2-piperidinone and 4-aminobutanoic acid.

4. Method according to one of the preceding claims, in which the rejuvenated catalyst has a group VI B metal content of between 1 and 40% by weight of oxide of said group VI B metal relative to the total weight of the rejuvenated catalyst and a group VIII metal content of between 0.1 and 10% by weight of oxide of said group VIII metal relative to the total weight of the rejuvenated catalyst.

5. Method according to one of the preceding claims, wherein the rejuvenated catalyst further contains phosphorus, the phosphorus content being between 0.3 and 10% by weight expressed as P ₂ O ₅ relative to the total weight of the rejuvenated catalyst and the phosphorus / (group VI B metal) molar ratio in the regenerated catalyst is between 0.1 and 0.7.

6. Method according to one of the preceding claims, wherein the rejuvenated catalyst is characterized by a specific surface of between 20 and 200 m ² / g, preferably between 30 and 180 m ² / g.

7. Method according to one of the preceding claims, in which the oxide support of the rejuvenated catalyst is chosen from aluminas, silica, alumina silicas or alternatively titanium or magnesium oxides used alone or in mixture with alumina or silica alumina.

8. Method according to one of the preceding claims, wherein in the rejuvenated catalyst contains residual carbon at a content of less than 2% by weight relative to the total weight of the rejuvenated catalyst.

9. Method according to one of the preceding claims, wherein in the rejuvenated catalyst contains contains contains residual sulfur at a content of less than 5% by weight relative to the total weight of the rejuvenated catalyst.

10. Method according to one of the preceding claims, in which the rejuvenated catalyst comes from a hydrodesulfurization process of an olefinic gasoline cut containing sulfur.

11. Method according to one of the preceding claims, in which the rejuvenated catalyst is subjected to a sulfurization step before or during the hydrodesulfurization process.

12. Method according to one of the preceding claims, wherein the gasoline cut is a gasoline from a catalytic cracking unit.

13. Method according to one of the preceding claims, which is carried out in a catalytic bed of a reactor of the fixed bed type containing several catalytic beds, at least one other catalytic bed upstream or downstream of the catalytic bed containing the rejuvenated catalyst in the direction of flow of the charge contains at least partly a fresh catalyst and / or a regenerated catalyst.

14. Method according to one of the preceding claims, which is carried out in at least two reactors in series of the fixed bed type or of the bubbling bed type, at least one of the reactors contains a rejuvenated catalyst while another reactor contains a fresh catalyst or a regenerated catalyst, or a mixture of a rejuvenated catalyst and a fresh and / or regenerated catalyst, and this in any order, with or without removal of at least part of the hhS from the effluent from the first reactor before treating said effluent in the second reactor.