CATALYST WHICH CAN BE USED IN HYDROTREATMENT AND WHICH INCLUDES GROUP VIII METALS AND GROUP VIB METALS, AND PREPARATION THEREOF USING CITRIC ACID AND C1-C4 DIALKYL SUCCINATE

A catalyst, process for its production and its use in the hydroprocessing.

Usually, a hydrotreating catalyst for hydrocarbon cuts aims at eliminating the sulfur compounds or nitrogen contained therein to carry for example a petroleum product specifications required (sulfur content, aromatic content and so on.) for a given application (automotive fuel, petrol or diesel, fuel oil, jet fuel). It can also be pre-processing it to remove impurities prior to conduct different transformation methods to modify the physicochemical properties, such as for example the methods of reforming, hydrocracking vacuum distillates, catalytic cracking, residue hydroconversion atmospheric or vacuum. The composition and the use of hydrotreating catalysts are particularly well described in the article of b. S. Clausen said, Topsoe T H, and P.A.s Massoth, derived from the work of ridges forensic science Technology, 11 (1996) space, SpringerVerlag. After sulfurization, more species present on the carrier, which do not all have good performance for the desired reactions. These species are particularly well described in the publication by Topsoe and Al was published in the 26 of ridges called review forensic science Imaging of 1984, page 395 - 420.

Curing of standards of car pollution in the European community (log official of the European Union, l76, 22 March 2003, directional 2003/70/ce, page l76/19/10 a-l76) has constrained the refiners is dramatically reducing the sulfur content in diesel fuels and gasoline (at most 10 parts per million by weight (ppmw) sulfur at 1^NC january 2009, against 50 ppm at 1^NC january 2005). Furthermore, the refiners are compelled to use fillers increasingly unresponsive hydroprocessing methods on the one hand because the crude are increasingly heavy and therefore contain more and more impurities, on the other hand due to the increased conversion processes in refineries. Indeed, they generate cuts more difficult to hydrotreating that cuts directly from the atmospheric distillation. By way of example, there can be mentioned the gas oil fraction derived from catalytic cracking, also named LCOs (guiding light cycle oil ring) with reference to its high content of aromatic compound. These cuts are coprocessed with the gas oil fraction derived from atmospheric distillation; they require catalysts having different functions and hydrogenating hydrodésulfurantes greatly improved relative to conventional catalysts to reduce the aromatic content to obtain a density and a cetane rating in compliance with the specifications.

Further, the conversion processes such as catalytic cracking or hydrocracking that use catalysts having an acid function, which make them particularly sensitive to the presence of nitrogen impurities, and particularly basic nitrogenous compounds. It is therefore necessary to use catalysts preprocessing said charges to remove these compounds. These hydrotreating catalysts require also a function hydrogenative improved since the first step hydrodenitrogenation is recognized as being a step of hydrogenation of the aromatic ring adjacent the C-N bond.

It is therefore interesting to find means of preparing the hydrotreating catalysts, so as to obtain novel catalysts with improved performance.

Adding an organic compound on the hydrotreating catalysts to enhance their activity is now well known to the skilled person. Many patents protect the use of different ranges of organic compounds, such as polyalcohols mono, di-or optionally etherified (w096/41848, WOOl/76741, us4012340, us3954673, ep601722). Catalysts modified with monoesters in c2 - c14 are described in the referenced applications and EPI046424 ep466568, however these modifications do not always sufficiently improve the catalyst performance for coping with the regarding the sulfur fuels are continually becoming more and more stringent for the refiners.

In order to prevent this Patent w02006/077326 Company proposes the use of the total catalyst comprising metals of group VIB and VIII, a refractory oxide as a carrier, and an organic compound having at least 2 carboxylic ester of formula functions r1-a 0 a-c0-to-r2-to-c0-a 0 a-r1 or r1 - c0 - 0 a-r2-a 0 a-c0-to-r1 wherein each Ri is independently alkyl Cl at cl8, c2 cl8 to alkenyl, aryl c6 to cl8, cycloalkyl c3 to c8, alkylaryl or arylalkyl c7 to c20, Ri 2 or together form a divalent group in c2 to cl8, and r2 is C2 Cl at cl8, c6 cl8 to arylene, cycloalkylene c3 to c7, or a combination thereof, the carbon chain hydrocarbon groups represented by ri and r2 can contain or carry one or more heteroatoms selected from N, S and O, and each of Ri and r2 can carry one or more substituents of formula (=0) - C. 0 to-r1 or - 0 c (=0) - LAN wherein ri is as defined above. One preferred uses the dialkyl succinate c1-to-c4, and particularly dimethyl succinate which is exemplified. These compounds may be introduced in the presence of a solvent (a large list of solvents is cited) or a carboxylic acid. Among the last thirty plus acid namely cited, the acetic acid is present but is not listed among the ten of preferred acids. It should be noted it is already that the citric acid is preferred.

The method for preparing the catalyst as described in U.S. Patent w02006/077326 comprises steps of maturation and heat treatment up to several days, for example 49 days to 115 days, which would very strongly the production of these catalysts and might therefore enhancements.

Other patents in the prior art describe a gain of activity linked to the combined use of an organic acid or an alcohol on a hydrotreating catalyst. Thus, the Patent application published under the n° to JP 1995 - 136523 of 340KK Japon Energy provides a solution comprising:

- prepare according to a first preferred embodiment of the invention a solution containing a catalyst support, one or more metals of group VI of the periodic table of elements, and group VIII, an organic acid. According to a second preferred embodiment of the invention, this solution also includes a phosphor precursor.

- a heat treatment carried out between 200 and 400 °c

- an impregnation of the catalyst obtained previously by an organic acid or an alcohol in a ratio of 0.1 to 2 per mole of metals.

A preferred embodiment of the invention then includes drying at a temperature less than 200 °c, while a second preferred mode includes a final heat treatment at a temperature greater than or equal to 400 °c.

It was found that these catalysts do not have a sufficient activity to meet the new environmental standards loadings increasingly reduced amount of hydrogen which arranges the refiners.

Similarly, the Patent claims a method w02005/035691 activation schematically which allows reducing in crystallised phase type c0m0o4 present on the regenerated catalysts comprising oxides of metals of fluid materials, the method comprising contacting the regenerated catalyst with an acid and an organic additive. To this end, the use of the combination citric acid (AC) and polyethylene glycol (pegylated) was carried out on regenerated catalyst in many instances.

The present invention relates to a preparation method thereof and catalyst, the catalyst being usable for hydrotreating and enabling an improvement in the catalytic performances (especially the catalytic activity) relative to prior catalysts. Indeed, it has been shown that the use of the torque c1 - c4 dialkyl succinate, dimethyl and particularly, and citric acid, optionally in the presence of acetic acid over a catalyst precursor dried, calcined or regenerated most unexpectedly results considerably improved catalytic activity.

More specifically, the invention relates to a catalyst comprising a carrier-based amorphous alumina, at least one dialkyl succinate c1-to-c4, citric acid, phosphorous and a hydro deshydrogénante function comprising at least one element of group VIII and at least one element of group VIB, catalyst in which the Raman spectrum comprises the strips to 990 and/or 974 cms and 1 features of at least one heteropolyanion Keggin, characteristic strips of said characteristic strips succinate and citric acid. In a preferred embodiment, the catalyst further comprises acetic acid.

The invention also relates to the sulfided catalyst. It is obtained by sulfurization of the catalyst described in the present application.

The water-dehydrogenating function comprises at least one element of group VIII (preferably a nickel/cobalt) and at least one group VIB metal (preferably molybdenum and/or tungsten). Preferably, the water-dehydrogenating function comprises molybdenum and cobalt and/or nickel.

The obtained catalyst has a characteristic Raman spectrum grouping:

1) characteristic bands of the Keggin-type heteropoly PXYnCLo *' and/or PYnO₄₀^{the X} ' wherein Y is a group VIB metal and X a group VIII metal.

Based Griboval, Coyle, Payen, Fourier, L. Core in ridges (1998) 45 Today of 277 Figure 3 I), alighting structure PCoMonCW are on dried catalyst to 232, 366, 943, 974 cm '¹ and after M T. driveway "NDA HeteropolyIsopolyoxometalates", Springer with Accordance, w 8, these strips are not characteristic of the nature of the atom X or Y, but much of the structure of the heteropolyanion. The higher the web characteristic of this type of heteropolyanion Keggin lacunary lies to 974 cm '¹ .

Based Griboval, Coyle, Gengembre, Payen, Fourier, L. Core, Russell, Journal (1999) 188 of ridges 102, Figure 1 has), alighting of PMonCW are state mass 1 'heteropolyanion, e.g. with cobalt in counter ion to 251, 603, 902, 970, 990 cm' VBE1 the higher the web feature of heteropolyanion Keggin lies at 990 cm 'VBE1 M T. driveway "NDA HeteropolyIsopolyoxometalates", Springer with Accordance, 8 P-, we also taught that these bands are not characteristic of the nature of the atom X or Y, but much of the structure of 1' heteropolyanion Keggin, complete, gap or substituted.

2) the characteristic bands (of) of succinate (O) (O) dialkyl used. The Raman spectrum of the dimethyl succinate constitutes a unique fingerprint of this molecule. In the spectral range 300 - 1800 cm '¹ , this spectrum is characterized by the following series of bands (only the strips the strongest are deferred, in cm '¹ ): 391, 853 (most intense band), 924, 964, 1739 cm '¹ The higher the web. characteristic of the dimethyl succinate is to 853 cm '¹ . The spectrum of the diethyl succinate has in the area this spectral alighting following: 861 (most intense band), 1101, 1117 cm '¹ . As is dibutyl succinate: 843, 1123, 1303, 1439.1463 cm '¹ and for diisopropyl succinate:

833, 876, 1149, 1185, 1469 (most intense band), 1733 cm '¹ .

3) characteristic bands citric acid whose major are: 785, 947, 956, 908 cm '¹ . The strips the strongest characteristics of citric acid are to 785 and 956 cm '¹ .

In a preferred embodiment, the catalyst also comprises acetic acid whose Raman line most intense feature is to 896 cm '¹ . The other bands characteristic of acetic acid are: 448, 623, 896 cm '¹ . The higher the web is to 896 cm '¹ .

The exact position of the bands, their shapes and their relative intensities may vary to some extent depending on recording conditions of the spectrum, while remaining characteristics of this molecule. The Raman spectra of organic compounds are also well documented either in the databases of Raman spectrum (see e.g., spectrally Preserving Database potting another evaluation, http://riodb01.ibase.aist.go.jp/sdbs/cgibin/direct_frame_top.cgi) either by the suppliers of the product (see e.g., www.sigmaaldrich.com).

The Raman spectra were obtained with a dispersive Raman spectrometer equipped with an argon laser (514 nm) ionized. The laser beam is focused on the sample using a microscope having an objective x50 long working distance. The laser power at the sample is of the order of 1 MW in. The Raman signal emitted by the sample is collected by the same objective and is dispersed using an 1800 rpm/min and then network collected by a CCD detector. The spectral resolution obtained is of the order of 0.5 cm '¹ . The spectral range is between 300 and recorded 1800 cm '¹ . The acquisition time was set to 120 s for each Raman spectrum recorded.

The dialkyl succinate is advantageously dimethyl succinate, dibutyl succinate, diisopropyl succinate.

Preferably, the dialkyl succinate used is dimethyl succinate, and the catalyst has in its spectrum Raman strips and/or main to 990 974 cm '¹ (e) the characteristic (of) (e) heteropolyanion Keggin, and 853 cm '¹ characteristic of the dimethyl succinate and 785 and 956 cm '¹ characteristics of citric acid and optionally to 896 cm '¹ characteristic of acetic acid.

Preferably the catalyst of the invention comprises a carrier made of alumina or silica-alumina.

The catalyst according to the invention may also include boron and/or fluorine and/or silicon, preferably boron and/or fluorine.

It is also herein describes a method for preparing the catalyst according to the invention, which comprises at least a step of impregnating a dried catalyst precursor to a temperature below 180 °c containing at least one hydrodehydrogenating element function and optionally phosphorus and an amorphous support, with a solution comprising combining citric acid (optionally with acetic acid) and dialkyl succinate c1 - c4 or without the presence of a phosphorus-containing compound, followed by a maturation step said catalyst precursor containing phosphor impregnated, and then a drying step at a temperature less than 200 °c, without calcination step (heat treatment in air) later; the catalyst obtained is preferably subjected to a sulfidation step.

Also provided is a method for preparing the catalyst according to the invention as described above but from a calcined catalyst precursor, said catalyst precursor having been prepared in the same way as previously but calcined after the drying step at a temperature lower than 180 °c. In the same way as previously, the catalyst obtained is preferably subjected to a sulfidation step.

The calcination (heat treatment under an oxidizing atmosphere) is performed at at least 350 °c during the preparation of a fresh (c'est to say not yet used). The temperature is lower than 600 °c and most often less than 550 °c, for example of 350 to 550 °c, preferably 400 to-520 °, or preferred way of 420 and 520° or 450 and 520 °, at temperatures below 500 °c are often advantageous.

Also provided is a method for preparing the catalyst according to the invention as described above, but from a spent catalyst (which has been used) and regenerated (combustion of the carbon deposited on the catalyst which has been used). Regeneration is conducted generally at temperatures between 350 and 550 °c, and most often between 400 and 520 °c, or between 420 and 520 °c, or alternatively between 450 and 520 °c, temperatures less than 500 or 480 °c is often advantageous.

Other embodiments may be envisaged, that reside in the present invention, for example after the drying step, the catalyst precursor is heat-treated above the drying temperature (which is at most 180 °c) and below the calcination temperature (which is at least 350 °c).

The methods of preparation ease and rapidity, unitary steps with not more than a few hours, lead to better and productivity industrial scale that the methods presented in the past.

Thus, the invention more accurately describes a method for preparing a catalyst comprising the following successive steps:

ab) preparing a catalyst precursor containing the elements of the water-dehydrogenating function, optionally phosphorus, said precursor having undergone at least one heat treatment

c) at least one impregnation step by an impregnation solution comprising at least one dialkyl succinate c1-to-c4, citric acid and at least one phosphorus compound, if the phosphorus was not introduced by impregnation in entirety to step a) and optionally acetic acid,

d) a maturation step,

e) a drying step at a temperature less than 200 °c, without subsequent calcination step.

The heat treatment of step ab) comprises at least one drying step at a temperature of not more than 180 °c. It may further include a step of calcining. It can also be included in a regeneration step.

In one preparation with a catalyst dried and optionally calcined, the inventive method comprises the following successive steps:

a) at least one step of impregnating a support amorphous alumina with at least one solution containing the elements of a hydro-dehydrogenating function, and optionally phosphorus; referred "catalyst precursor"

b) drying at a temperature below 180 °c optionally followed by calcination at a temperature of at least 350 °c, and preferably between 420 and 520 °c; referred the product "dried or calcined catalyst precursor"

c) at least one impregnation step by an impregnation solution comprising at least one dialkyl succinate c1-to-c4, citric acid, at least one phosphorus compound, if the phosphorus was not introduced in entirety to step a) and optionally acetic acid,

d) a maturation step,

e) a drying step at a temperature less than 200 °c, without subsequent calcination step.

The invention also provides a method for preparing a catalyst, from a catalyst precursor which is a spent catalyst comprising. the following successive steps:

'b.' has) regeneration of spent catalyst comprising a function a hydro-dehydrogenating and optionally phosphorus,

c) at least one impregnation step by an impregnation solution comprising at least one dialkyl succinate c1-to-c4, citric acid and optionally (and preferably) at least one phosphorus compound if the phosphorus was not completely inserted into the catalyst for step 'b.'), and optionally acetic acid

d) a maturation step,

e) a drying step at a temperature less than 200 °c, without subsequent calcination step.

Preferably, at the end of step e) undergoes a step f) sulfiding. The invention also relates to the sulfided catalyst.

Thus that will be described later, the method according to the invention is preferably achieved with the following modes taken alone or in combination: the support is made of alumina or silica alumina; the entire function hydrogenative is introduced during step a); all of the phosphorus is introduced during step a); the dialkyl succinate is dimethyl succinate; step c) is carried out in the presence of water and/or ethanol; step d) is performed at a temperature between 17 and 60 °c or 50 °c; step e) is carried out at a temperature between 80 and 180 °c.

In one embodiment, step b) of drying is performed at a temperature below 180 °c without heat treatment or subsequent calcination.

For example, the inventive method comprises the following successive steps:

a) at least one impregnation step to dry said support with a solution containing all of the elements of a hydro-dehydrogenating function, and all of the phosphorus,

b) drying at a temperature between 75 and 130 °c without subsequent heat treatment,

c) at least one step of dry impregnation by an impregnation solution comprising dimethyl succinate and citric acid, and optionally acetic acid,

d) a stage of maturation to 17 above 60 °,

e) a drying step, preferably under nitrogen, at a temperature between 80 and 160 °c, without subsequent heat treatment step.

The catalyst precursor containing the function and a water-dehydrogenating amorphous alumina-based as well as its mode of preparation are described below.

Said catalyst precursor obtained at the end of step a) of the method according to the invention can be prepared in large part by all methods well known to the skilled person.

Said catalyst precursor contains a function a hydro-dehydrogenating. Advantageously, it contains phosphorus and/or boron and/or fluorine as a dopant as well as the amorphous support.

The amorphous support said catalyst precursor is based on alumina. It typically contains more than 25%, even more than 35% and preferably more than 50% by weight alumina more preferred ., it only contains alumina or siüce-alumina with possibly the (e) metal (metals) and/or (e) (e) the dopant that has been fed outside impregnations (introduced e.g. when preparing - kneading, peptizing... of the holder or its shaping).

The support is obtained after shaping (extruding preferably). It is subjected to a calcination, typically between 300 and 600 degrees Celsius.

Preferably, the support is made of alumina. Preferably, the alumina is gamma alumina and preferably said support consists of gamma alumina.

In another preferred case, it is a silica-alumina containing more than 25%, even more than 35% and preferably at least 50% (or more) by weight alumina. The silica content in the medium is at most 50% by weight, most often less than or equal to 45% by weight, preferably less than or equal to 40% by weight. Preferably the support is silica-alumina.

The silicon sources are well known to the skilled person. Include by way of example silicic acid, silica in powder form or colloidal form (silica sol), tetraethylorthosilicate (and OEt) if₄ .

It is understood by "amorphous support" a medium that does not contain crystalline phases wherein outside that could exist in the alumina or silica-alumina.

The function hvdro-to-deshvdrogênante said catalyst precursor is provided by at least one of the group BLV and by at least one group VIII element.

The total content of hydro-dehydrogenating elements is advantageously greater than 6% by weight of oxide relative to the total weight of the catalyst. The elements of the group VIB molybdenum and tungsten, and molybdenum in particular. The elements of group VIII non-noble elements are preferred and especially cobalt and nickel. Advantageously, the function a hydro-dehydrogenating comprises (and preferably consists of) molybdenum, nickel and/or cobalt.

Advantageously, the hydrogenative function is selected from the group formed by combinations of the elements cobalt-molybdenum, nickel-molybdenum, or nickel-cobalt-molybdenum, nickel-molybdenum-tungsten or.

In the case where a significant activity in hydrodesulfurization, hydrodenitrogenation or and in hydrogenation of aromatics is desired, the function hydro deshydrogénante is advantageously maintained by the association of nickel and molybdenum; a combination of nickel and tungsten in the presence of molybdenum can also be advantageous. In the case of type feeds vacuum distillates or heavier, combinations of cobalt-nickel-molybdenum can be advantageously used.

The precursors of molybdenum which can be used are also well known to the skilled person. For example, sources of molybdenum, may be used oxides and hydroxides, molybdic acids and salts thereof in particular ammonium salts such as ammonium molybdate, ammonium heptamolybdate, phosphomolybdic acid and salts thereof (h3pm012o40), and optionally silicomolybdic acid (h4s1m012o40) and salts. The sources of molybdenum can also be any hétéropolycomposé Keggin-type, polyoxometalate gappy, substituted polyoxometalate, anions, heteropolyanions, Strandberg, for example. The preferred molybdenum trioxide and the heteropolycompounds (Anderson) type Strandberg, polyoxometalate, polyoxometalate gap or substituted polyoxometalate.

The tungsten precursors which can be used are also well known to the skilled person. For example, tungsten sources, can be used oxides and hydroxides, tungstic acids and salts thereof in particular ammonium salts such as ammonium tungstate, ammonium metatungstate, phosphotungstic acid and their salts, and optionally silicotungstic acid (h4s1w12o40) and salts. The sources of tungsten can also be any hétéropolycomposé Keggin-type, polyoxometalate gappy, substituted polyoxometalate, anions, for example. Are preferentially used oxides and ammonium salts such as ammonium metatungstate or the Anderson-Keggin-type, polyoxometalate gap or polyoxometalate susbtitué.

The amount of precursor (e) of (of) element of group VIB (e) is advantageously between 5 and 40% by weight of oxides of group VIB relative to catalyst precursor after heat treatment step ab) or b), preferably between 8 and 35% by weight and most preferably between 10 and 30% by weight.

The precursors of (of) element (e) of group VIII which can be used are advantageously selected from oxides, hydroxides, the alkaline metal, carbonates and nitrates, e.g. the hydroxycarbonate nickel, cobalt carbonate or cobalt hydroxide are used preferably.

The amount of precursor (e) of (of) element (e) of group VIII is advantageously between 1 and 10% by weight of oxides of group VIII with respect to the catalyst precursor after heat treatment step ab) or b), preferably between 1.5 and 9% by weight and most preferably, between 2 and 8% by weight.

The function hydro deshydrogénante said catalyst precursor may be introduced into the catalyst at various levels of the preparation and in various ways. Said function is always water-deshydrogénante introduced, at least in part and preferably wholly, by impregnating the formed carrier. It can also be introduced in part during the forming of said amorphous support.

In the case where the function hydro deshydrogénante is introduced in part during the forming of said amorphous support, it can be inserted in part (for example at most 10% by weight of an element (e) group VIB, for example introduced by kneading) only at the time of kneading with an alumina gel matrix chosen as, the remainder of the (of) element (e) hydrogenating (e) then being introduced later. Most preferably, when the function hydro deshydrogénante is introduced to part at the time of kneading, the proportion of component (e) of group VIB introduced in this step is less than 5% by weight of the total amount of component (e) of the Virulence group introduced on the final catalyst. Most preferably, at least one (or all) of group VIB is introduced at the same time as at least one (or all) of group VIII, regardless of the mode of input. These methods and amounts for the introduction of elements are used especially in the case where the water-dehydrogenating function consists in Como.

In the case where the function a hydro-dehydrogenating is introduced at least partially and preferably totally, after patterning said amorphous support, introducing said water-deshydrogénante function on the amorphous. can be advantageously carried out by one or more impregnation is excess solution on the support shaped and calcined, or preferably by one or more dry impregnation and, preferably, by a dry impregnation of said molded support and calcined, with solutions containing the precursor salts of metals. Very preferably, the function a hydro-dehydrogenating is introduced in its entirety after patterning said amorphous support, by a dry impregnation from said support with an impregnation solution containing the precursor salts of metals. Introducing said water-deshydrogénante function can also be advantageously carried out by one or more impregnation of the molded support and calcined, by a solution of the (or) precursors) of the active phase. In the case where the elements are introduced in several impregnation of corresponding precursor salts, an intermediate drying step of the catalyst is generally performed, at a temperature between 50 and 180 °c, most preferably between 60 and 150 °c and most preferably between 75 and 130 °c.

Phosphorus is also introduced into the catalyst. Flax other catalyst doping can also be introduced which is preferably selected from boron, fluorine or mixed. The dopant is an element added, which in itself does not have any catalytic character but which increases the catalytic activity of the (of) metal (metals).

The boron source can be boric acid, preferably orthoboric acid h3bo3, the biborate or ammonium pentaborate, boron oxide, boric esters. The boron can be introduced for example by a boric acid solution in a water/alcohol or in a mixture of water/ethanol amine.

The phosphorus source is preferred h3po4 orthophosphoric acid, its salts and esters as but ammonium phosphates are also suitable. The phosphorus may also be introduced concurrently with the (O) element of group VIB (O) in the form of heteropolyanions Keggin, polyoxometalate gap, or substituted polyoxometalate Strandberg type.

The fluoride sources which can be used are well known to the skilled person. For example, the fluoride anions can be introduced in the form of hydrofluoric acid or its salts. These salts are formed with alkali metals, ammonium or an organic compound. In the latter case, the salt is advantageously formed in the reaction mixture by reaction between the organic compound and hydrofluoric acid. The fluorine can be introduced for example by impregnation of an aqueous solution of hydrofluoric acid, ammonium fluoride or ammonium bifluoride or otherwise.

The dopant is advantageously introduced into the catalyst precursor in an amount of oxide of said dopant to the catalyst precursor after heat treatment step ab) or b):

- 40% weight of between 0 and, preferably between 0 and 30% by weight and more preferably between 0 and 20% by weight, preferably between 0 and 15% by weight and more preferably between 0 and 10% weight when said dopant is boron; when boron is present, preferably the minimum amount is 0.1% or 0.5%.

- between 0.1 to 20% (or 0.5%), preferably between 0.1 and 15% (or 0.5%) and even more preferably between 0.1 and 10% (or 0.5%), when said dopant is phosphorus. This amount represents the amount of phosphorus introduced by impregnation, and for the preparation of the fresh catalyst, it represents the amount which is impregnated during step a) and step c) if the latter has not been impregnated or has not been impregnated in entirety to step a). In the regenerated catalyst, it represents the amount of phosphorus present on the spent catalyst after regeneration more than impregnated during step c). The phosphorus present on the regenerated catalyst comes from the impregnation which took place during the preparation of this catalyst in a fresh state.

0 - 20% range and weight, preferably between 0 and 15 % weight and even more preferably between 0 and 10% by weight, when said dopant is fluorine; when the fluorine is present, preferably the minimum amount is 0.1% or 0.5%.

The phosphor is always present. The phosphor is usually introduced in the impregnation of the support with at least one of the function elements are water-dehydrogenating (step a) of the process) and/or is introduced during the impregnation with succinate and (e) (e) acid (step c) of the method). Preferably it is completely inserted into step a) c'est to say on the catalyst precursor.

Advantageously, the phosphorus is, in whole or in part, in admixture with the precursors (e)) of the water-dehydrogenating function, on the amorphous support shaped, preferably extruded alumina or silica-alumina, by a dry impregnation of said amorphous support with a solution containing the precursor salts of the metals and the (e) (e) of the precursor (of) doping (e).

Most preferably, the same applies for other dopants. The dopant may also be introduced when the synthesis of the support. It may also be introduced just before or just after the peptization of the chosen template, such as for example and preferably aluminum oxyhydroxide (boehmite alumina) alumina precursor. However, phosphorus should be introduced on the formed carrier, preferably by impregnation, and advantageously by dry impregnation.

More preferably, the "catalyst precursor" in step a) of the method according to the invention is prepared with an impregnating solution comprising at least one precursor of each of the water-dehydrogenating function, in the presence of a phosphor precursor, the amorphous support being made of alumina or silica alumina.

Introducing said water-deshydrogénante function and optionally a dopant in or on the calcined support shaped is then advantageously followed by a step b) drying during which the solvent metal salts precursors (or) metal oxides (to) (solvent which is typically water) is removed, at a temperature between 50 and 180 °c, most preferably 150 °c or between 60 and 65 and 145 °c and most preferably between 70 and 140 °c or between 75 and 130 °c.

In a method according to the invention, the step of drying the "dried catalyst precursor" thus obtained is never followed by a step of heat treatment in air at a temperature greater than 200 °c. Advantageously, it takes place in these temperature ranges to a temperature of at most 150 °c.

Thus, generally in step a) of the method according to the invention, said "catalyst precursor" is obtained by dry impregnation of a solution comprising a precursor (or) (e) of the water-dehydrogenating function, and phosphorus on a support amorphous alumina calcined shaped, followed by drying at a temperature below 180 °c.

It is thus obtained is a "dried catalyst precursor" at the end of step b).

In another method of preparation, after step a), the catalyst precursor is dried and then calcined at a temperature of at least 350 °c. The calcination temperature is less than 600 °c and most often less than 550 °c, for example of 350 to 550 °c, and preferably between 400 and 520 °c, or most preferably between 420 and 520 °c or between 450 and 520 °c, temperatures below 500 °c are often advantageous.

In another method of preparation, the spent catalyst (containing the function a hydro-dehydrogenating and phosphorus) is regenerated (step called 'b.'). This method will be detailed further. The regenerated catalyst obtained is subjected to steps hereinafter described.

In accordance with the step Cl of the method according to the invention, said dried or calcined catalyst precursor or regenerated is impregnated with an impregnating solution comprising at least one dialkyl succinate c1 - c4 (and in particular the dimethyl succinate) and citric acid and optionally acetic acid.

Compounds are advantageously introduced into the impregnating solution in step c) of the method according to the invention in an amount corresponding (relative to the catalyst precursor after heat treatment step ab) or b):

- at a molar ratio of dialkyl succinate (e.g. dimethyl) by element of group VIB (e) impregnated with the catalyst precursor of between 0.15 to 2 moles/moles, preferably between 0.3 to 1.8 moles/moles, most preferably between 0.5 and 1.5 moles/mole and very preferably, between 0.8 and 1.2 moles/moles, and

- at a molar ratio of citric acid by element of group VIB (e) impregnated with the catalyst precursor in the range 0.05 to 5 moles/moles, preferably between 0.1 or 0.5 to 4 moles/moles, most preferably between 1.3 and 3 moles/mole and very preferably, between 1.5 and 2.5 moles/moles,

- and, when the acetic acid is present, at a molar ratio of acetic acid by element of group VIB (e) impregnated with the catalyst precursor of between 0.1 to 6 moles/moles, preferably 0.5 to 5 molar range/moles, most preferably between 1.0 and 4 moles/mole and very preferably, between 1.5 and 2.5 moles/moles,

- the molar ratio of citric acid + acetic acid by element of group VIB (e) impregnated with the catalyst precursor of between 0.15 to 6 moles/moles.

According to step c) of the method according to the invention, the combination dialkyl succinate and citric acid (optionally with acetic acid) is introduced onto the catalyst precursor (dried, calcined, regenerated) by at least one impregnation step and preferably by a single impregnation step an impregnation solution on said catalyst precursor.

This combination can advantageously be deposited in one or more steps either by impregnation in slurry, either by impregnation in excess, either by dry impregnation, or by any other means known to the skilled person.

According to a preferred embodiment of step c) of the method of preparation according to the invention, step c) is a single impregnation step to dry.

According to step c) of the method according to the invention, the impregnating solution of step c) comprises at least the combination of the dialkyl succinate c1 - c4 (in particular dimethyl) and citric acid. Preferably it also contains acetic acid.

The impregnating solution utilized in step c) of the method according to the invention may be aided by any non-protic solvent known to those skilled in the including toluene, xylene.

The impregnating solution utilized in step c) of the method according to the invention may be aided by any polar solvent known to the skilled person. Wherein said polar solvent is advantageously selected from the group consisting of methanol, ethanol, water, phenol, cyclohexanol, taken alone or as a mixture. Said polar solvent used in step c) of the method according to the invention may also advantageously be selected from the group consisting of propylene carbonate, DMSO (dimethyl sulfoxide) or sulpholane, singly or in combination. Most preferably, a polar protic solvent is used. A list of the usual polar solvents and their dielectric constant can be found in the book " DNA in solvent based solvent effects levels in-Biologique joining technology, Reichardt's C, Wiley Interscience-to-HCV, 3eme editing, 2003, page 472 - 474).

Preferably, the step c) is carried out in the presence of water and/or ethanol. Preferably, it contains pure dialkyl succinate and citric acid and optionally acetic acid, as well as water and/or ethanol.

The dialkyl succinate used is preferably comprised in the group consisting of dimethyl succinate, diethyl succinate, dipropyl succinate, succinate diisopropyie and dibutyl succinate. Most preferably, the dialkyl succinate c1 - c4 used is dimethyl or diethyl succinate. Very preferably, the dialkyl succinate c1 - c4 used is dimethyl succinate. At least one dialkyl succinate c1 - c4 is used, preferably a single, and preferably dimethyl succinate.

In accordance with step d) of the method the preparation according to the invention, the catalyst precursor or the regenerated catalyst impregnated from step c) is subjected to a maturation step. It is advantageously carried out under atmospheric pressure. The temperature is generally between 17 °c and 60 °c or 50 °c and 17 °c. Generally the maturing time is ten minutes and forty eight hours and preferably between thirty minutes and five hours, is sufficient. Longer durations are not excluded. A simple means of adjusting the maturing time is characterizing the formation of heteropolyanions Keggin by Raman spectroscopy in the catalyst precursor dried impregnated from step c) of the method according to the invention. Very preferably, to increase the productivity without changing the amount of heteropolyanions reformed, the aging period is thirty minute to four hours. More preferably, the aging period is between thirty minutes to three hours.

In accordance with the step heptene and method the preparation according to the invention, the catalyst precursor or catalyst obtained in step d) is subjected to a drying step.

The purpose of this step is to obtain a catalyst a transportable, storable, and handleable, designed for loading of the hydrotreater. It is advantageously, according to the embodiment of the invention selected, removing all or part of the optional solvent having allowed the introduction of the combination of the dialkyl succinate c1 - c4 (in particular dimethyl) and citric acid. In all cases, and particularly in the case where the combination c1 - c4 dialkyl succinate (in particular dimethyl) and citric acid is used alone, it is to give a high dry as catalyst, in order to prevent the extruded does adhere to each other during steps of transportation, storage, handling or loading.

Step e) of drying the method according to the invention is advantageously carried out by any technique known to the skilled person. It is advantageously carried out at atmospheric pressure or reduced pressure. This step is preferably carried out at atmospheric pressure.

This step e) is advantageously carried out at a temperature less than 200 °c, usually from about 50 °c to less than 200 °c, preferably between 60 and 190 °c and most preferably, between 80 and 180 °c. Advantageously, it takes place in these temperature ranges and without subsequent heat treatment at a temperature higher than 200 °c.

It is advantageously carried out in the tunnel kiln. fluidized bed, fluidized bed vibrated, fluidized-bed exchangers, in traversed bed or any technology for drying and/or calcining preferably fluidized bed. preferably, the gas used is either air, or an inert gas such as argon or nitrogen. Very preferably the drying is carried out under nitrogen.

Preferably, this step has a duration of between 30 minakeda TES and 4 hours and preferably between 45 minutes and 3 hours.

Upon completion of step e) of the method according to the invention, there is obtained a dried catalyst, which is not subjected to any subsequent calcination step or subsequent heat treatment at a temperature higher than 200 °c.

The catalyst obtained after step d) or step e) has a Raman spectrum comprising the bands most severe to 990 and 974 cm '¹ (anderson Keggin-type), the bands corresponding succinate (dimethyl succinate for the higher the web is to 853 cm^-1 ), and characteristic strips of citric acid, of which the strongest to 785 and 956 cm '¹ and optionally the strips of acetic acid which is most intense 896 cm '¹

As described above, in another embodiment, the catalyst precursor on which the succinate and the acid (or acids) are impregnated on spent catalyst regenerated hydrogenative whose function is provided by at least one element of group VIB and by at least one group VIII element. Their contents and characteristics corresponding to those previously mentioned. The supports are also the same. Advantageously, the catalyst contains phosphorus, which preferably has been introduced by impregnation during the preparation of this catalyst in a fresh state.

Said regenerated catalyst has undergone a heat treatment step called "regeneration" in the presence of oxygen, pure or diluted. This step to overcome at least part of the coke present on the catalyst by combustion, there is not a chemical treatment during this step.

The regeneration treatment can be performed at a temperature between 350 and 550 °c, and generally between 450 and 520 °c, or between 420 and 520 °c, or between 400 and 520 °c. It is made preferably between 420 and 500 °c, or between 450 and 520 °c depending on the nature of the carbon burning. Those skilled in the optimizes the temperature required for burning coke (or precursor thereof) while avoiding or minimizing the sintering of the catalyst.

During this step a temperature monitoring is necessary so as to enable the combustion of the coke but not to exceed 550 °c on the catalyst, including locally. The overshooting of the temperature of 550 °c could for example have coevolvedmillimetersth to damage its porosity. This check is known to the skilled person. The temperature within the bed during the regeneration phase may be controlled by any technique known to the skilled person, such as the arrangement of thermocouples in the mass of the catalyst.

When this step is carried out with a mixture comprising oxygen, the diluent may be selected from nitrogen or other inert gas. The oxygen content can be fixed throughout the treatment or variable during the regeneration process. For example, the temperature will evolve during the treatment according to several phases, the temperatures will vary from room temperature to the final temperature coke combustion, always less than 550 °c. The duration of the regeneration step will depend on the amount of catalyst to be treated and the nature and quantity of the coke present. This duration may vary in practice of 0.1 hours to a few days. Most often, it is between 1 hour and 20 hours.

The method for preparing the catalyst according to the latter mode then comprises the following steps that are the same as other embodiments:

c) at least one step of dry impregnation by an impregnation solution comprising the dialkyl succinate c1 - c4 (preferably diméthyie) and citric acid, and optionally acetic acid,

d) a maturation step, typically at a temperature between 17 and 60 °c,

e) a drying step, preferably under nitrogen, to a temperature below 200 °c, usually at least 80 °c, preferably between 80 and 180 °, without subsequent calcination step.

Prior to use, it is advantageous to convert the dried catalyst (after step e) in a sulfided catalyst to form its active species. This activation phase or sulfurization is by well known to the skilled artisan, and advantageously in an atmosphere sulpho-reducing in the presence of hydrogen and hydrogen sulfide.

Upon completion of step e) of the method according to the invention (regardless of the dried, calcined, regenerated... of the catalytic precursor), said dried catalyst thus obtained is advantageously subjected to a step f) of sulfurization, without intermediate calcination step. It is obtained a sulfided catalyst, according to the invention.

Said catalyst is advantageously dried sulfurated manner off-site or in-situ. The agents sulphuring are the H range₂ S or any other sulfur-containing compound used for the activation of hydrocarbon feedstocks for sulfiding the catalyst. Said sulfur containing compounds are advantageously chosen from alkyldisulfures such as for example dimethyl disulfide (RMD), the alkylsulfures, such as for example dimethyl sulfide, the nbutylmercaptan, the polysulfides tertiononylpolysulfure type compounds such as for example the TPS and 37 or the TPS and 54 by the company ARKEMA, or any other compound known to the skilled person to achieve good sulfurization of the catalyst. Preferred manner the catalyst is sulfided in-situ in the presence of an agent and a hydrocarbon feed. Very preferably the catalyst is sulfided in-situ in the presence of a hydrocarbon feed additivated dissulfure of dimethyl.

Finally, another object of the invention is a process for hydrotreating of hydrocarbon feedstocks using the catalyst according to the invention. Such methods are for example hydrodesulfurization process, hydrodenitrogenation, for determining a criterion, hydrogenation of aromatic and hydroconversion.

Dried the catalysts obtained by the method according to the invention and preferably having previously been step f) sulfiding are advantageously used for the hydroprocessing reactions of hydrocarbon feeds such as petroleum fractions, coal or cuttings from the produced hydrocarbons from natural gas and more particularly for hydrogenation reactions, hydrodenitrogenation, hydrodearomatization, hydrodesulfurization, for determining a criterion or hydroconversion of hydrocarbon feeds.

In these uses, the catalysts obtained by the process according to the invention and preferably having previously been step f) sulfiding show improved activity compared to catalysts previously known. These catalysts can also advantageously be used in pre-processing loads of the hydrodesulfurization catalytic cracking or residues or the hydrodesulfurization pushing the gas oils (ultra-low wheel ULSD sulfide a diesel).

The charges used in hydrotreating processes are for example oils, gas oils, vacuum gas oils, atmospheric resids, vacuum resids, atmospheric distillates, vacuum distillates, heavy fuels, oils, waxes and paraffins, waste oil, deasphalted residues or of crudes, loads from processes for thermal or catalytic conversions, taken alone or in mixtures. The charges that are processed, and in particular those cited above, generally contain heteroatoms such as sulfur, oxygen and nitrogen and, for heavy loads, they contain most often also metals.

The process conditions used in the methods using the reactions for hydrotreating of hydrocarbon feedstocks described above generally are the following: the temperature is advantageously between 180 and 450 °c, and preferably between 250 and 440 °c, the pressure is advantageously between 0.5 and 30 mpa, and preferably between 1 and 18 mpa, the hourly space velocity is advantageously between 0.1 and 20 hr '¹ and preferably between 0.2 and 5 hr "¹ , and the hydrogen/feedstock ratio expressed as volume hydrogen, measured under standard conditions of temperature and pressure, by the volume of liquid feed is advantageously between 50 l/l to 2000 l/l.

The examples that follow demonstrate the gain important activity on the catalysts prepared according to the method of the invention compared to catalyst prior and specify the invention without however limiting its scope.

Example 1: preparation of comparative b1 b2 and regenerated catalyst

A matrix composed ultrathin tabular boehmite or alumina gel, from the company Condéa GmbH on generating chemiluminescence was used. The gel was mixed with an aqueous solution containing nitric acid at 66% (7% by weight of acid per gram of dry gel), then kneaded during 15 min. At the end of this kneading, the paste obtained is passed through a die having cylindrical holes of diameter equal to 1.6 mm. The extruded are then dried overnight at 120 °c, then calcined at 600 °c during 2 hours in moist air containing 50 g of water per kg of dry air. This provides extruded support only composed of low crystallinity cubic gamma alumina.

On the alumina carrier described above is formed into the extruded shape is added cobalt, molybdenum and phosphorus. The impregnating solution is prepared by dissolving hot molybdenum oxide (24.34 grams) and cobalt hydroxide (5.34 gm) in the phosphoric acid solution (7.47 gm) in aqueous solution. After dry impregnation, the extrudates are allowed to mature at room temperature (20 °c) water-saturated atmosphere for 12 hr, then they are dried overnight to 90 °c and calcined at 450 °c during 2 hours. Obtained the calcined catalyst A. the final composition of the catalyst has expressed in oxide form is then as follows: m0o3=22.5 ± 0.2 (% by weight), COOalkyl=4.1 ± 0.1 (% by weight) and P₂ 0₅ =4.0 ± 0.1 (% by weight).

The calcined catalyst is loaded into a drive has traversed bed and sulfided by a straight run gas oil with added 2% by weight of dimethyl disulfide. A test HDS a mixture of straight run gas oil and a gas oil from the catalytic cracking process is then conducted for 300 hours. After testing, the spent catalyst is discharged, collected and washed with toluene at reflux and then separated into two batches. The first batch is regenerated combustion furnace controlled by introducing for each bearing temperature increasing amounts of oxygen, thereby limiting the exotherm linked to coke combustion. The final step of regeneration is 450 °c. The regenerated catalyst is analyzed as DRX, noting the absence of peak at 26° characteristic of the presence of c0m0o4 crystallized. This catalyst will be subsequently noted ΔBL. The second batch of washed spent catalyst is regenerated in the muffle furnace at 450 °c without control of the exotherm of coke burn. The timers are performed after regeneration analysis shows the presence of a fine line 26 degrees, characteristic of the presence of c0m0o4 crystallized. Further, this catalyst be now noted b2 bright blue has a very pronounced.

The catalyst is prepared by impregnation of Cl drying of a solution of citric acid and dimethyl succinate-diluted in ethanol at b1 catalyst. The contents target citric acid (AC) and dimethyl succinate-(DMSU) are 10% and 15% respectively (either ac/mo=0, 50 mole/mole and DMSU mole/mole/mo=0, 44). After a maturing time of 24 hours for retorting at room temperature, the catalyst is dried under a stream of nitrogen (1 nl/g/g) during 1 hour.

The catalyst Cl has been analyzed by Raman spectroscopy. It has the band including the main strip of the AHP Keggin to 990 cm '¹ characteristic strips and citric acid and dimethyl succinate-respectively to 785 cm^-1 and 851 cm '¹ .

The catalyst is prepared by impregnation c2 drying of a solution of citric acid dimethyl succinate and acetic acid diluted in ethanol at b2 catalyst which has a phase c0m0o4 crystallized. The contents target citric acid (AC), in dimethyl succinate-(DMSU) and acetic acid (A.A) are respectively of 15%, 10% and 20% weight (either ac/mo=0, 50 mole/mole, DMSU/mo=0, 44 mole/mole and ΑΑ / Μο=2, 13/mole mole). After a maturing time of 24 hours for retorting at room temperature, the catalyst is dried under a stream of nitrogen (1 nl/g/g) during 1 hour.

The catalyst c2 was analyzed by Raman spectroscopy. It has the band including the main strip of the AHP Keggin to 990 cm '¹ characteristic strips and citric acid, dimethyl succinate and acetic acid respectively to 785 cm '¹ , 851 cm '¹ and 896 cm '¹ .

The catalyst is prepared in the same way as in the example 3 but from the regenerated catalyst ΔBL.

The catalyst is prepared in the same way as in the example 2 but from the regenerated catalyst b2.

Example 4 : Comparative test catalysts ΔBL. 2 Β. LC. C2. LC bis and c2bis in hydrogenation of toluene in cyclohexane under pressure and in the presence of hydrogen sulfide.

The catalysts previously described, sulfided in-situ dynamic in the fixed-bed tube reactor traversed from a master type Microcat (manufacturer: company Da Vinci), the fluids flowing from top to bottom, the activity measurements are performed immediately after the hydrogenative sulphidation under pressure and recirculating air with the hydrocarbon feedstock which has served to sulfurize the catalysts.

The sulfurization and load test is composed of 5.8% of dimethyldisulphide (RMD), 20% toluene and cyclohexane 74.2% (by weight).

The sulfidation carried out on room temperature to 350 °c, with a temperature ramp of 2 °c/min., a Whr=4l¹ and H₂ Hc=450 nl/1 /. The test is carried out at 350 °c to catalytic Whr=2:00^{1 _} and H₂/ HC-equivalent to that of the sulfurizing, with minimal sample 4 recipes which are analyzed by gas chromatography.

This gives a measurement of the catalytic activities stabilized equal volumes of catalysts in the hydrogenation reaction of toluene.

The conditions detailed activity measurement are as follows:

- Total pressure: 6.0 mpa

- Pressure of toluene: 0.37 mpa

Cyclohexane - pressure: 1.42 mpa

- 0.22 Mpa pressure methane

- Hydrogen pressure: 3.68 mpa

H2s - pressure:

- Catalyst volume:

between 2 and 4 mm)

- Hourly space velocity:

0.22 Mpa

4 cm³ (extradited of length

- Temperature sulfidation and test: 350 °c

The liquid effluent samples are analyzed by gas chromatography. The determination of the molar toluene unconverted (T-) and hydrogenation products thereof concentrations (methylcyclohexane (MCC6), the éthylcyclopentane (EtCC5) and the diméthylcyclopentanes (DMCC5)) compute a hydrogenation rate of toluene XHYD defined by:

ν ^ (c/o) - 100 χ

MCC6 + Andc PK + DMCCS

T + mcc6 EtCCSDMCCS + +

The hydrogenation reaction of toluene being of order 1 under the test conditions used and the reactor which behaves as an ideal plug flow reactor, activity is calculated hydrogenative Afjyj) catalysts by applying the formula:

Ahyd~

100

100 X

HÏD/

Table 1 compares the relative hydrogenating activities and b2 b1 catalysts (non-compliant), and catalysts Cl and c2 (inventive) equal to the ratio of the activity of the catalyst on the catalyst activity b2 (non-compliant) taken as a reference (100% activity).

The regenerated catalyst under uncontrolled conditions b2 (non-compliant) has less activity than the regenerated catalyst b1 (non-compliant).

The table 1 shows that the catalyst containing the additives of Cl (compliant) prepared by adding 15% by weight citric acid (AC) and 10% dimethyl succinate-(DMSU) at catalyst b1 have enhanced activity relative to the starting catalyst of 16%, the addition of acetic acid causes the gain to 20% (Clbis catalyst).

The table 1 shows that the catalyst additived c2 the bis (compliant) prepared by adding 15% by weight citric acid (AC) and 10% dimethyl succinate-(DMSU) at catalyst b2 have enhanced activity relative to the starting catalyst of 24%, the addition of acetic acid causes the gain to 37% (catalyst c2).

These results show the effect particular catalytic and surprising combination citric acid (CA) and dimethyl succinate (DMSU) on regenerated catalyst (according to the invention) and in particular to a regenerated catalyst which would if b2 crystalline phases). This effect is further enhanced by the addition of acetic acid.