FR2815041A1 - MODERATE PRESSURE HYDRO-CRACKING DIESEL PRODUCTION PROCESS - Google Patents

Abstract

The invention concerns a moderate pressure hydrocracking method (that is partial hydrogen pressure higher than 70 bars up to a maximum of 100 bars) with conversion of at least 80 % by volume, of a feedstock having a temperature T5 ranging between 250 and 400 DEG C and a temperature T95 of not more than 470 DEG C (T5 and T95 measured according to ASTM-D2887), so as to produce a diesel fuel having a 95 % distillation point less than 360 DEG C, a sulphur content of not more than 50 ppm and a cetane index higher than 51. The method operates with or without recycling the liquid effluent. It can advantageously be integrated in a refinery configuration comprising catalytic cracking. The invention also concerns an installation for implementing said method.

Description

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The invention relates to a process with moderate pressure hydrocracking, for the production of very high quality diesel with high yields.

The invention also relates to a process including said hydrocracking process and a catalytic cracking process, as well as the installation that can be used for carrying out said method.

The refining industry must now find refining schemes to adapt to the stringent fuel quality standards that will be in force in Europe in 2005. The maximum sulfur content of diesel fuel must be at most 50 ppm. The 95% distillation point (ASTM D-86) of diesel, currently 360oC, will probably be reduced, for example by 10oC, which would currently represent for a refinery a decrease of 5% in volume of diesel produced It is also envisaged to at least halve the current polyaromatics contents of about 11% by mass. The cetane number required would, at the same time, be increased beyond 51, for example from the current value of 51 to 52.

At the same time, diesel demand is steadily growing and demand increases are expected to be around 20% in the decade.

The distillation of the crude is not sufficient to cover the production of diesel, diesel is currently produced by high pressure hydrocracking processes (generally at least 120 bar hydrogen partial pressure) dealing with heavy loads which are fillers having a T95 temperature most often of the order of at least 500oC, T95 being the temperature of the 95% volume point obtained by simulated distillation (ASTM-D28 87). Heavy compounds are cracked into lighter compounds, some of which is found in the middle distillate cut (diesel and kerosene) of hydrocracking distillation. Such high pressure methods are conventional.

To reach the new standards, crude distillation diesel will have to undergo deep hydrodesulfurization. In addition, high pressure hydrocracking is a solution that can be expensive. A more advantageous solution has therefore been sought which, moreover, could be integrated into the current units in order to make the best use of the existing resources of the refinery.

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Le procédé exposé dans la présente demande est un procédé d'hydrocraquage fonctionnant à des pressions modérées (au-delà de 70 bars et d'au plus 100 bars en pression partielle hydrogène) qui permet d'obtenir directement un diesel répondant au spécifications 2005 à partir de charges relativement légères dans des conditions plus économiques que l'hydrocraquage haute pression.

The process described in the present application is a hydrocracking process operating at moderate pressures (above 70 bar and at most 100 bar hydrogen partial pressure) which makes it possible to directly obtain a diesel that meets the 2005 specifications. from relatively light loads under more economical conditions than high pressure hydrocracking.

hydrocarbonées ayant une température T 5 comprise entre 250 et 400oC et une température T95 d'au plus 470oC, ledit procédé comprenant un hydrotraitement puis un hydrocraquage sous une pression partielle d'hydrogène supérieure à 70 bars et d'au plus 100 bars, à une température d'au moins 320oC, avec un rapport volumique H2/charge d'au moins 200 NI/NI, une vitesse volumique horaire de 0, 15-7h-1 et le procédé réalisant une conversion d'au moins 80% volume et l'effluent liquide obtenu par hydrocraquage étant distillé pour séparer le diesel. De préférence, le résidu de distillation est recyclé dans le procédé après purge. More specifically, the invention relates to a process for producing a diesel having a distillation point 95% below 360oC, a sulfur content of at most 50 ppm and a cetane number greater than 51, said process treating the feedstocks.

hydrocarbons having a temperature T 5 of between 250 and 400 ° C. and a temperature T95 of at most 470 ° C., said process comprising hydrotreatment and then hydrocracking under a hydrogen partial pressure of greater than 70 bar and at most 100 bar, at a temperature of a temperature of at least 320 ° C., with a H 2 / charge ratio of at least 200 Nl / Ni, an hourly space velocity of 0.15-7 hr -1 and the process achieving a conversion of at least 80% by volume and hydrocracking liquid effluent being distilled to separate the diesel. Preferably, the distillation residue is recycled to the process after purging.

Fillers, hydrotreating, hydrocracking The feedstocks treated in the process have a point T5 of between 250 and 400.degree. C. and preferably between 280 and 370.degree. Point T5 represents the temperature of the 5% volume point obtained by simulated distillation (ASTM-D28 87).

Generally, the charges have a T5 point between 320-400oC or between 320-370oC. Very advantageously can be added to these loads a fraction of diesel, for example heavy diesel from the atmospheric distillation of the crude, which most often has a T5 point of the order of at least 280oC. This heavy diesel fraction can just as easily be obtained directly in the atmospheric residue.

This provision (diesel addition) is particularly advantageous. Indeed, it allows to treat with a hydrotreatment followed by hydrocracking at a moderate pressure a heavy part of the diesel fraction which is loaded with nitrogen compounds and sulfur most difficult to hydrotreat. Therefore, conventional hydrotreating can be used to treat the remaining diesel fraction, and there is no need for expensive investment.

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Moreover, by treating this heavy part of the diesel in the process according to the invention, the hydrodesulfurization of the heavy fraction is carried out with an improvement in its qualities (cetane number higher than that which would have been obtained by severe hydrotreatment alone). .

Usable fillers also have a T95 temperature of not more than 470oC, more preferably not more than 450oC, or better still within the range of 390-430oC, T95 being the 95% point temperature obtained by simulated distillation (ASTM-D28 87 Light vacuum distillates, a light fraction of a conventional vacuum gas oil (VGO) (for example, the lightest half), heavy atmospheric gas oils (HGO), mixtures of the said fillers or mixtures of said feeds with at least one diesel fraction for example from the distillation of crude or a unit of FCC (catalytic cracking).

The hydrocarbon feedstocks treated generally have sulfur contents of 0.2 to 4% by mass and nitrogen of 100 to 3500 ppm by weight. They are therefore generally previously hydrotreated before being hydrocracked so as to lower the contents of organic nitrogen (that is to say of nitrogen forming part of organic molecules) below 80 ppm, or better still 50 ppm and preferably below 10 ppm, and the organic sulfur contents (ie, sulfur being part of organic molecules) below 200 ppm and preferably below 50 ppm. These hydrotreated loads (called clean) can then be subjected to hydrocracking.

The conditions of the hydrotreatment are generally: pressure of 5-25 MPa, with a hydrogen partial pressure of greater than 70 bars and a maximum of 100 bars, preferably of at least 80 bars, or at least 100 bars. 85 bar, temperature of at least 320oC, generally at least 350oC and at most 450oC most often, or even at most 430oC, H2 volume ratio / load of at least 100 NI / 1, and most often between 100-
2000 NI / 1 or 300-2000 Nit /),

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vitesse volumique horaire de 0, 1-10h-1, de préférence 0, 15-7h-1, et avantageusement 0, 05-4h-1.

hourly volume velocity of 0, 1-10h-1, preferably 0, 15-7h-1, and preferably 0, 05-4h-1.

The conversion carried out in the hydrotreatment is generally at least 10% by volume and less than 40% by product boiling below 350oC.

The hydrotreatment can be carried out either in the hydrocracking reactor and in at least one bed preceding the first bed of the hydrocracking catalyst, in the direction of flow of the feedstock, or in an independent reactor preceding the reactor. hydrocracking. There is or there is no intermediate separation of the regenerated gases by the hydrotreatment. The first mode (same reactor) without Intermediate separation is preferred. Also included in the process is an embodiment in which the hydrotreatment is carried out in the refinery very upstream of the hydrocracking, intermediate treatments may also be performed.

The intrinsic charge is, at least in part, in the presence of hydrogen brought into contact with at least one hydrocracking catalyst under the following operating conditions: hydrogen partial pressure greater than 70 bar and at most 100 bar reference temperature of at least 80 bar or at least 85 bar, temperature of at least 320 ° C., generally at least 350 ° C. and at most 450 ° C. most often, or even at most 430 ° C. , H2 volume ratio / load of at least 200NI / NI and most often between 300-2000NI / NI.

- Hourly volume velocity 0, 15-7h-1, preferably 0, 05-4h-1.

The process can operate with or without recycling the distillation residue of the hydrocracking effluent (unconverted fraction). When recycling is carried out, it is carried out to the hydrocracking reactor if it is separated from that of hydrotr alation, for example, or else to the feedstock entering the reactor where hydrotreatment and hydrocracking are carried out.

Under these conditions, at the level of the process as a whole, the conversion to products boiling below 350 ° C. is at least 80% by volume, and more generally at least 90% by volume, or at least 95% by volume. .

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Hydrotreating catalysts Conventional catalysts can be used which contain at least one amorphous support and at least one hydro-dehydrogenating element (generally at least one group VIB and VI non-noble element, and most often at least one a group VIB element and at least one non-noble group V element!).

Very advantageously, a hydrotreatment catalyst comprises at least one matrix, at least one hydro-dehydrogenating element chosen from the group formed by the elements of the group VIS and group VIII of the periodic table, optionally at least one promoter element deposited on the catalyst and selected from the group formed by phosphorus, boron and silicon, optionally at least one element of group VIIA (preferred chlorine, fluorine), and optionally at least one element of group VIlS (preferred manganese), optionally at least minus one element of the VB (preferred niobium) group.

In general, the hydrotreatment catalyst contains: 5-40% by weight of at least one element of the non-noble VIS and VIII groups (% oxide) - 0-20% of at least one promoter element chosen from phosphorus boron, silicon (% oxide), preferably 0.1-20%; advantageously boron and / or silicon are present, and possibly phosphorus.

- 0-20% of at least one VIlS group element (manganese for example) - 0-20% of at least one group VIIA element (eg fluorine, chlorine) - 0-60% of at least one element VB group (niobium for example) - 0, 1-95% of at least one matrix, and preferably alumina Preferably, this catalyst contains boron and / or silicon as a promoter element, with possibly in addition phosphorus as another promoter element. The contents of boron, silicon and phosphorus are then from 0.1 to 20%, preferably from 0.1 to 15%, and still more preferably from 0.1 to 10%.

The matrices that can be used alone or as a mixture are, by way of nonlimiting example, alumina, halogenated alumina, silica, silica-alumina, clays (for example, natural clays such as kaolin or bentonite), magnesia, titanium oxide, boron oxide, zirconia, aluminum phosphates, titanium phosphates, zirconium phosphates, coal, aluminates. It is preferred to use matrices containing alumina, in all these known forms

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de l'Homme du métier, et de manière encore plus préférée les alumines, par exemple l'alumine gamma.

those skilled in the art, and even more preferably the aluminas, for example gamma alumina.

The role of hydro-dehydrogenating function is preferably filled by at least one metal or metal compound of non-noble groups VIII and VI preferably selected from molybdenum, tungsten, nickel and cobalt. Preferably, this role is ensured by the combination of at least one element of Group VIII (Ni, Co) with at least one element of the group VIS (Mo, W).

This catalyst may advantageously contain phosphorus; in fact, it is known in the prior art that this compound provides two advantages to hydrotreatment catalysts: an ease of preparation, especially when impregnating solutions of nickel and molybdenum, and a better hydrogenation activity.

In a preferred catalyst, the total concentration of metal oxides of groups V and VIII is between 5 and 40% by weight and preferably between 7 and 30% and the weight ratio expressed as metal oxide between metal (or metals) of the group VIS on metal (or metals) group VIII is preferably between 20 and 1.25 and even more preferred between 10 and 2. The concentration of phosphorus oxide P205 will be less than 15% by weight and preferably 10% by weight.

Another preferred hydrotreatment catalyst which contains boron and / or silicon (and preferably boron and silicon) generally contains, in% by weight with respect to the total mass of the catalyst, at least one metal selected from the following groups and with the following contents: 3 to 60%, preferably 3 to 45% and even more preferably 3 to 30% of at least one metal of the VIS group and optionally 0 to 30%, preferably 0 to 30%; at 25% and even more preferably from 0 to 20% of at least one metal of the Veil group, the catalyst additionally containing at least one support selected from the following groups with the following contents: 0 to 99%, advantageously 0.1 to 99%, preferably 10 to 98% and even more preferably 15 to 95% of at least one amorphous or poorly crystallized matrix, said catalyst being characterized in that it also contains,

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- 0, 1 à 20%, de préférence de 0, 1 à 15% et de manière encore plus préférée de 0, 1 à 10% de bore et/ou 0,1 à 20%, de préférence de 0,1 à 15% et de manière encore plus préférée de 0,1 à 10% de silicium. et éventuellement, - 0 à 20%, de préférence de 0,1 à 15% et de manière encore plus préférée de 0,1 à
10% de phosphore, et éventuellement encore, - 0 à 20%, de préférence de 0,1 à 15% et de manière encore plus préférée de 0,1 à
10% d'au moins un élément choisi dans le groupe VIIA, de préférence le fluor.

From 0.1 to 20%, preferably from 0.1 to 15% and even more preferably from 0.1 to 10% boron and / or 0.1 to 20%, preferably from 0.1 to 15%; and even more preferably 0.1 to 10% silicon. and optionally, 0 to 20%, preferably 0.1 to 15% and even more preferably 0.1 to
10% phosphorus, and optionally still, - 0 to 20%, preferably 0.1 to 15% and even more preferably 0.1 to
10% of at least one element selected from group VIIA, preferably fluorine.

In general, the following atomic ratios are preferred: a group VIII metal / Group VIB metal atomic ratio between 0 and 1, a B atomic ratio / Group VIB metals between 0.01 and 3, a Si / Group VIB atomic ratio of between 0.01 and 1.5, a P / Group VIB atomic ratio of between 0.01 and 1, an elemental atomic ratio of the VilA group. Group VIB metals between
0.01 and 2.

Such a catalyst has an activity in hydrogenation of aromatic hydrocarbons and in hydrodenitrogenation and in hydrodesulphurization more important than the catalyst formulas without boron and / or silicon, and also has a greater hydrocracking activity and selectivity than the catalytic formulas known in the art. prior art. The catalyst with boron and silicon is particularly interesting. Without wishing to be bound by any theory, it seems that this particularly high activity of the catalysts with boron and silicon is due to the strengthening of the acidity of the catalyst by the joint presence of boron and silicon on the matrix which induces on the one hand an improvement of the hydrogenating, hydrodesulphurizing and hydrodenitrogenating properties and, on the other hand, an improvement of the hydrocracking activity with respect to the catalysts usually used in the hydroconversion hydrorefining reactions.

The preferred catalysts are the NiMo and / or NiW catalysts on alumina, also the NiMo and / or NiW catalysts on alumina doped with at least one element included in the group of atoms formed by phosphorus, boron, silicon and fluorine, or else NiMo and / or NiW catalysts on silica-alumina, or on silica-

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alumine-oxyde de titane dopée ou non par au moins un élément compris dans le groupe des atomes formés par le phosphore, le bore, le fluor et le silicium.

alumina-titanium oxide doped or not by at least one element included in the group of atoms formed by phosphorus, boron, fluorine and silicon.

Another type of catalyst of particular interest (especially in improved activity) in hydrotreating, contains a partially amorphous Y zeolite which will be described later in the hydrocracking catalysts.

Prior to the injection of the feedstock, the catalysts used in the process according to the present invention are preferably subjected beforehand to a sulphurization treatment making it possible, at least in part, to convert the metal species into sulphide before they come into contact with the feedstock. load to be processed. This activation treatment by sulfurization is well known to those skilled in the art and can be performed by any method already described in the literature either in-situ, that is to say in the reactor, or ex-situ A method conventional sulfurization known to those skilled in the art consists of heating in the presence of hydrogen sulfide (pure or for example under a stream of a hydrogen / hydrogen sulfide mixture) at a temperature between 150 and 800oC, preferably between 250 and 600oC, usually in a crossed-bed reaction zone.

Hydrocracking catalysts A preferred catalyst comprises at least one zeolite Y, at least one matrix and a hydro-dehydrogenating function. Optionally, it may also contain at least one element chosen from boron, phosphorus and silicon, at least one element of G VIIA (chlorine, fluorine for example), at least one element of group VIIB (manganese for example), with least one element of the group VB (niobium for example).

The catalyst contains at least one porous or poorly crystallized oxide type mineral matrix. By way of non-limiting example, mention may be made of aluminas, silicas, silica-aluminas, aluminates, alumina-boron oxide, magnesia, silica magnesia, zirconia, titanium oxide and clay. , alone or in mixture.

The hydro-dehydrogenating function is generally provided by at least one element of group VI B (for example molybdenum and / or tungsten) and / or at least one element of group V! ! ! non-noble (eg cobalt and / or nickel) classification

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périodique des éléments. Un catalyseur préféré contient essentiellement au moins un métal du groupe VI, eUou au moins un métal du groupe V ! ! ! non noble, la zéolithe Y et de l'alumine. Un catalyseur encore plus préféré contient essentiellement du nickel, du molybdène, une zéolithe Y et de l'alumine.

periodic elements. A preferred catalyst essentially contains at least one Group VI metal, or at least one Group V metal! ! ! non-noble, zeolite Y and alumina. An even more preferred catalyst essentially contains nickel, molybdenum, zeolite Y and alumina.

The catalyst optionally contains at least one element selected from the group formed by boron, silicon and phosphorus. Advantageously, the catalyst optionally contains at least one element of group VIIA, preferably chlorine and fluorine, optionally at least one element of group VIIB (manganese for example), optionally at least one element of group VB (niobium for example) Boron, silicon or phosphorus may be in the matrix, the zeolite or are preferably deposited on the catalyst and then mainly localized on the matrix. A preferred catalyst contains B and / or Si as a promoter element deposited with preference for more phosphorus promoter. The quantities introduced are 0.1-20% by weight of catalyst calculated as oxide.

The element introduced, and in particular silicon, mainly located on the matrix of the support can be characterized by techniques such as the Castaing microprobe (distribution profile of the various elements), transmission electron microscopy coupled with an X analysis of the components of the catalysts, or even by establishing a distribution map of the elements present in the catalyst by electron microprobe.

In general, a preferred hydrocracking catalyst advantageously contains: - 0.1% to 80% by weight of zeolite Y - 0.1 - 40% by weight of at least one element from groups VIB and VIII (% oxide) - 0, 1-99.8% weight of matrix (% oxide) - 0-20% by weight of at least one element selected from the group consisting of P, B, Si (% oxide), preferably 0.1-20 % - 0-20% weight of at least one element of the group Vt! A, preferably 0.1-20% - 0-20% by weight of at least one group VIlS element, preferably 0.1-20% - 0-60% by weight of at least one group VB element, preferably 0.1-60%

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 For silicon, in the range 0-20% it is counted only the added silicon and not that of the zeolite.

The zeolite may optionally be doped with metal elements such as, for example, rare earth metals, especially lanthanum and cerium, or noble or non-noble metals of group VIII, such as platinum, palladium or ruthenium, rhodium, iridium, iron and other metals such as manganese, zinc, magnesium.

Different zeolites Y can be used.

spécifications : un rapport molaire gtoba ! Si02/A < 203 compris entre environ 6 et 70 et de manière préférée entre environ 12 et 50 : une teneur en sodium Inférieure à 0,15 % poids déterminée sur la zéolithe calcinée à 1 100 C ; un paramètre cristallin a de la maille élémentaire compris entre 24,58 x 10-10 m et 24,24 x 10 m et de manière -10-10 préférée entre 24,38 x 10 m et 24,26 x 10 m ; une capacité CNa de reprise en ions sodium, exprimée en gramme de Na par 100 grammes de zéolithe modifiée, neutralisée puis calcinée, supérieure à environ 0,85 ; une surface spécifique déterminée par la méthode B. E. T. supérieure à environ 400 m2/g et de préférence supérieure à 550 m2/g, une capacité d'adsorption de vapeur d'eau à 25 C pour une pression partielle de 2,6 torrs (soit 34,6 MPa), supérieure à environ 6 %, et avantageusement, la zéolite présente une répartition poreuse, déterminée par physisorption d'azote, comprenant entre 5 et 45 % et de préférence entre 5 et 40 % du volume poreux total de la zéolithe contenu dans des pores de diamètre situé entre -10-10 20 x 10 m et 80 x 10 m, et entre 5 et 45 % et de préférence entre 5 et 40 % du volume poreux total de la zéolithe contenu dans des pores de diamètre supérieur à - 10 -1

80 x 10 m et généralement inférieur à 1000 x 10 m, le reste du volume poreux - 10 étant contenu dans les pores de diamètre inférieur à 20 x 10 m. A particularly advantageous HY acid zeolite is characterized by different

specifications: a molar ratio gtoba! SiO2 / A <203 between about 6 and 70 and preferably between about 12 and 50: a sodium content below 0.15% by weight determined on the zeolite calcined at 1100 C; a crystalline parameter has elemental mesh of between 24.58 x 10-10 m and 24.24 x 10 m and preferably -10-10 between 24.38 x 10 m and 24.26 x 10 m; a sodium recovery CNa capacity, expressed in grams of Na per 100 grams of modified zeolite, neutralized and then calcined, greater than about 0.85; a specific surface area determined by the BET method of greater than about 400 m 2 / g and preferably greater than 550 m 2 / g, a water vapor adsorption capacity at 25 C for a partial pressure of 2.6 torr (ie 34 , 6 MPa), greater than about 6%, and advantageously, the zeolite has a porous distribution, determined by nitrogen physisorption, comprising between 5 and 45% and preferably between 5 and 40% of the total pore volume of the zeolite content in pores of diameter between -10-10 20 x 10 m and 80 x 10 m, and between 5 and 45% and preferably between 5 and 40% of the total pore volume of the zeolite contained in pores with a diameter greater than - 10 -1

80 x 10 m and generally less than 1000 x 10 m, the remainder of the pore volume being contained in pores less than 20 x 10 m in diameter.

A preferred catalyst using this type of zeolite contains a matrix, at least one dealuminated zeolite Y having a crystalline parameter of between 2.424 nm and 2.455 nm, preferably between 2.426 and 2.388 nm, an overall SiO 2 / AlO 3 molar ratio of greater than 8, cation content of the alkaline-earth or alkaline metals and / or rare-earth cations such that the atomic ratio (n × M n +) / Al is less than 0.8, preferably less than 0.5 or even 0.1, a specific surface area determined by the BE T method greater than 400 m 2 / g, preferably greater than 550 m 2 / g, and a water adsorption capacity at 25 C for a P / Po value of 0.2,

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 greater than 6% by weight, said catalyst also comprising at least one hydro-dehydrogenating metal, and silicon deposited on the catalyst.

In an advantageous embodiment according to the invention, a catalyst comprising a partially amorphous Y zeolite is used for hydrocracking.

The term "partially amorphous Y zeolite" means a solid having: a peak level which is less than 0.40, preferably less than about 0.30, a crystalline fraction expressed relative to a reference Y zeolite under sodium form (Na) which is less than about 60%, preferably less than about 50%, and determined by X-ray diffraction.

Preferably, the partially amorphous Y solids zeolites used in the composition of the catalyst according to the invention have at least one (and preferably all) of the following other characteristics: n / a global Si / Al ratio greater than 15, preferably greater than 20 and less than 150; IV / a Si / AlIV ratio of framework greater than or equal to the overall Si / Al ratio; vi a pore volume at least equal to 0.20 ml / g of solid, a fraction of which , between 8% and 50%, consists of pores having a diameter of at least 5 nm (nm) or 50 Å.

 Specific surface area of 210-800 m 2 / g, preferably 250-750 m 2 / g and advantageously 300-600 m 2 / g. Peak levels and crystalline fractions are determined by X-ray diffraction, using a Procedure Derived from ASTM Method D3906-97 Determination of Relative X-ray Diffraction Intensities of Faujasite-Type-Containing Materials. This method may be referred to for the general conditions of application of the procedure and, in particular, for the preparation of samples and references.

A diffractogram is composed of the characteristic lines of the crystallized fraction of the sample and of a background, caused mainly by the diffusion of the amorphous fraction or microcrystalline of the sample (a weak diffusion signal is linked to the apparatus, air , sample holder, etc.) The peak rate of a zeolite is the ratio,

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 in a predefined angular zone (typically 8 to 400 when copper Ka radiation is used, 1 = 0, 154 nm), the zeolite line area (peaks) on the overall area of the diffractogram (peaks + background). This ratio plcs / (peaks + bottom) is proportional to the amount of crystallized zeolite in the material. To estimate the crystalline fraction of a sample of zeolite Y, the peak levels of the sample will be compared to that of a reference considered as 100% crystallized (NaY for example). The peak rate of a perfectly crystalline NaY zeolite is in the range of 0.55 to 0.60.

The peak level of a conventional USY zeolite is 0.45 to 0.55, its crystalline fraction relative to a perfectly crystalline NaY is from 80 to 95%. The peak level of the solid which is the subject of the present invention is less than 0.4 and preferably less than 0.35. Its crystalline fraction is therefore less than 70%, preferably less than 60%.

The partially amorphous zeolites are prepared according to the techniques generally used for dealumination, from commercially available Y zeolites, that is to say which generally have high crystallinities (at least 80%). More generally, zeolites having a crystalline fraction of at least 60%, or at least 70%, may be used.

The Y zeolites generally used in hydrocracking catalysts are manufactured by modifying commercially available Na-Y zeolite. This modification leads to zeolites said stabilized, ultra-stabilized or dealuminated. This modification is carried out by at least one of the dealumination techniques, and for example the hydrothermal treatment, the acidic attack. Preferably, this modification is carried out by combining three types of operations known to those skilled in the art. Hydrothermal treatment, ionic exchange and acid attack Another particularly interesting zeolite is a zeolite which is not dealuminized globally and is very acidic.

By zeolite not dealuminated globally is meant a zeolite Y (structural type FAU, faujasit) according to the nomenclature developed in "Atlas of zeolites structure types", W. M. Meier, D. H. Oison and Ch. Baerlocher, 4th revised Edition 1996, Elsevier.

The crystalline parameter of this zeolite may have decreased by extraction of aluminum from the structure or framework during the preparation but the ratio

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SIO2/AI203 global n'a pas changé car les aluminiums n'ont pas été extraits chimiquement Une telle zéolithe non désaluminée globalement a donc une composition en silicium et aluminium exprimée par le rapport SiO2/Al2O3 global équivalent à la zéolithe Y non désaluminée de départ. Les valeurs des paramètres (rapport SIO2/AI2O3 et paramètre cristallin sont données plus loin.). Cette zéolithe Y non désaluminée globalement peut être sous la forme hydrogène soit être au moins partiellement échangée avec des cations métalliques, par exemple à l'aide de cations des métaux alcalino-terreux et/ou des cations de métaux de terres rares de numéro atomiques 57 à 71 inclus. On préférera une zéolithe dépourvue de terres rares et d'alcalino-terreux, de même pour le catalyseur.

Overall SIO2 / Al203 has not changed because the aluminas have not been chemically extracted. Such a zeolite, which is not dealuminated overall, therefore has a composition of silicon and aluminum expressed by the overall SiO 2 / Al 2 O 3 ratio equivalent to the non-dealuminated starting Y zeolite. . The values of the parameters (SIO2 / AI2O3 ratio and crystalline parameter are given below). This zeolite Y not dealuminated globally can be in the hydrogen form or be at least partially exchanged with metal cations, for example using alkaline earth metal cations and / or atomic number rare earth metal cations. to 71 included. A zeolite devoid of rare earths and alkaline earths is preferable, as is the catalyst.

The zeolite Y not globally dealuminated generally has a crystalline parameter greater than 2.438 nm, an overall SiO 2 / AJ 2 O 3 ratio of less than 8, a SiO 2 / Al 2 O 3 molar ratio of framework less than 21 and greater than the overall SiO 2 / AbO 3 ratio. The zeolite globally not dealuminated. can be obtained by any treatment that does not extract the aluminum from the sample, such as, for example, steam treatment, treatment with SiCl4, etc.

Another type of catalyst that is advantageous for hydrocracking contains an amorphous acid oxide matrix of phosphorus doped alumina type, a non-dealuminated Y zeolite which is globally and highly acidic, and optionally at least one group VIIA element and in particular fluorine.

The invention is not limited to the cited and preferred Y zeolites, but other types of Y zeolites may be used in this process.

Prior to the injection of the feedstock, the catalyst is subjected to a sulfurization treatment making it possible, at least in part, to transform the metal species into sulfide before they come into contact with the feedstock to be treated. This activation treatment by sulfurization is well known to those skilled in the art and can be performed by any method already described in the literature either in-situ, that is to say in the reactor, or ex-situ.

A conventional sulphurization method well known to those skilled in the art consists of heating in the presence of hydrogen sulphide (pure or for example under a stream of a hydrogen / hydrogen sulphide mixture) at a temperature of between 150 and 8000.degree. C., preferably between 250 and 6000C, generally in a crossed-bed reaction zone.

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Lorsque les catalyseurs d'hydrotraitement et d'hydrocraquage sont dans le même réacteur ou dans deux réacteurs sans séparation intermédiaire, ils sont sulfurés dans le même temps.

When the hydrotreatment and hydrocracking catalysts are in the same reactor or in two reactors without intermediate separation, they are sulphurized at the same time.

Separation and products The liquid effluent from the hydrocracking is then distilled to separate a naphtha cut, a diesel cut, possibly a kerosene cut (which may sometimes be included at least partly in the diesel cut), LPG light gases. There remains a liquid residue which can be advantageously recycled in the process after purging generally.

It is obvious that the hydrogen has also been previously separated from the liquid effluent, which could subsequently be stripped before being distilled.

Unexpectedly, it has been found that with the process according to the invention, diesels of very good quality are obtained directly which meet the specifications and without any additional treatment (severe hydrodesulphurisation, hydrogenations, etc.) being necessary to improve his qualities.

Thus, the process makes it possible to directly produce a diesel having a distillation point 95% volume lower than 3600C, and generally this point is at most 350 C or even more than 3400C, having a sulfur content of at most 50 ppm, and generally at most 10 ppm, having a cetane number of at least 52 and most generally at least 54 and preferably having a polyaromatic content of at most 6% wt. plus 1%, and preferably a pour point less than -10 C, and preferably an aromatics content of less than 15 wt%.

It is also produced in this process a good quality kerosene having a smoke point greater than 20 mm, preferably greater than 22 mm, and having a sulfur content of less than 50 ppm, preferably less than 10 ppm. Kerosene may possibly be at least partly sent to the diesel pool, depending on the needs of the operator.

It is quite remarkable to obtain such qualities of diesel without further treatment and for a much lower investment than a high pressure hydrocracking, while allowing the valuation of "light" loads of the refinery such as

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que les gazoles actuels qui, du fait de la sévérisation des spécifications, se retrouveront soit en excès soit devoir subir des traitements ultérieurs sévères.

current gas oils which, because of the severity of the specifications, will find themselves either in excess or have to undergo subsequent severe treatments.

As for the yields of middle distillate (kerosene + diesel) produced, they are at least 60% volume, most often at least 65% volume. The other products formed are LPG light gases (represent at most 10% by weight and more generally at most 5% by weight) and naphtha (generally at least 20% by volume).

The Figures Hereinafter will be described briefly the method with reference to the figures. Figure 1 shows an embodiment of the moderate pressure hydrocracking process.

FIGS. 2B, 2C and 3,4 illustrate an integration of this method in a catalytic cracking installation, FIG. 2A showing the prior art.

The process for hydrocracking at moderate pressure is shown schematically in FIG. 1. The feedstock to be treated enters via line 1, it is in this figure, added with the recycling of the hydrocracking residue via line 2 and hydrogen via line 3. It passes through a heat exchanger 4 mixed with the recycled hydrogen brought by the pipe 5, then through a heater 6 before being introduced into the reactor (or zone) 7 hydrocracking at moderate pressure possibly containing upstream the hydrotreating zone (s).

The reactor 7 contains at least one catalytic bed 8 of at least one hydrocracking catalyst. Preferably, it may contain upstream of the first bed 8 at least one hydrotreatment catalyst. The liquid effluent from the reactor and exiting through line 9 passes through exchanger 4 and then into a gas-liquid separator 10 separating hydrogen which is recycled via line 5 to the hydrocracking reactor 7.

The separated liquid effluent exiting through line 11 is preferably sent to a stopper 12 which separates naphtha and light gases through line 13 and a resulting effluent exiting through line 14 is distilled in the atmospheric distillation column 15. This arrangement schematically illustrates an embodiment of distillation. Any other provision known to those skilled in the art resulting in the separation of the same products is also suitable.

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There is thus obtained a diesel evacuated by line 16 and a residue recycled via line 2 to the hydrocracking reactor, except for purging via line 17.

Optionally, a kerosene is obtained.

Thus, the product separation zone separates a hydrocracking residue having a boiling point greater than at least 535 ° C, and comprises a purge pipe for said residue and optionally a pipe for recycling said purged residue to the zone or reactor of hydrocracking.

To facilitate the reading of the figure, it has not shown the compressors and utilities that are known to those skilled in the art.

The hydrocracking process described here can very advantageously be integrated into the refinery at the level of a catalytic cracking process (generally FCC: fluidized catalytic cracking).

The result is a combined process producing both good quality diesel and naphtha (for gasoline production).

une température T95 d'au plus 4700C, au moins une zone d'hydrotraitement de ladite charge ou de ladite fraction, au moins une zone d'hydrocraquage à pression modérée de ladite fraction, ladite pression étant supérieure à 70 bars et d'au plus 100 bars, au moins une zone de séparation des produits permettant d'obtenir un diesel ayant un point de distillation 95% inférieur à 360 C, une teneur en soufre d'au plus 50 ppm et un indice de cétane supérieur à 51. The invention also relates to an installation for carrying out the method described above. This installation comprises: a distillation column of a hydrocarbon feedstock making it possible to separate at least one fraction having a temperature T5 of between 2500 ° C. and 4000 ° C. and

a temperature T95 of at most 4700C, at least one hydrotreatment zone of said charge or fraction, at least one hydrocracking zone at moderate pressure of said fraction, said pressure being greater than 70 bar and at most 100 bar, at least one product separation zone to obtain a diesel having a distillation point 95% below 360 ° C, a sulfur content of at most 50 ppm and a cetane number greater than 51.

In a more particular embodiment shown below, the plant comprises: an atmospheric distillation column of said raw feedstock for separating at least naphtha, diesel and an atmospheric residue; a vacuum distillation column for treating said residue; atmospheric, and for separating at least one vacuum distillate fraction and a vacuum residue, wherein the atmospheric distillation column or the vacuum distillation column comprises at least one pipe recovering a fraction.

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 having a temperature T5 between 2500C and 400 C and a T95 temperature of at most 470 C, the installation also comprises at least one hydrotreatment zone of said fraction followed by at least one hydrocracking zone at moderate pressure and at least one product separation zone and making it possible to obtain a diesel having a distillation point 95% lower than 3600C, a sulfur content of at most 50 ppm and a cetane number greater than 51.

To better understand the invention and its interest, it has been schematized in Figure 2A the prior art and Figure 2B the invention, and the method of the invention will be described using these figures.

Figure 2A shows a current installation. The crude hydrocarbon feedstock (or crude oil) which arrives via the pipe 20 is distilled in the atmospheric column 21. It is separated from one (this term will generally be understood also to be at least one) naphtha fraction (line 22), a jet fuel fraction ( 23), a diesel fraction (line 24).

The atmospheric residue exiting through line 25 is distilled under vacuum in column 26 of vacuum distillation. A vacuum distillate fraction is separated (line 27) and a vacuum residue remains (line 38).

Said vacuum distillate is sent to a catalytic cracking unit 28 (generally in a fluidized bed) which, by this process, produces, among others, naphtha discharged via line 29, a strongly aromatic diesel type fraction (light cycle oil LCO). discharged through line 30, and a "slurry" or residue exiting through line 31.

Most often, the vacuum residue is processed in a visbreaking unit 39, which produces, among others, naphtha (line 40) and diesel (line 41) which are of poor quality. The visbreaking residue (line 42) is only usable as fuel and slurry, a portion of the LCO can be used to flow this fuel.

FIG. 2B shows the process and the installation according to the invention, associating a hydrocracking with moderate pressure and a catalytic cracking.

The markings of FIG. 2A are recognized, and in order not to weigh down the diagram, the visor reducer has not been represented, but it is generally present in the installation.

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L'installation selon l'invention (figure 2B) comprend en plus de celle de l'art antérieur (figure 2A), l'unité d'hydrocraquage 32 à pression modérée qui reçoit une fraction légère issue de la distillation sous vide amenée dans la conduite 33 L'unité 32 comprend le (s) réacteur (s) ou zone (s) d'hydrocraquage à pression modérée et les séparations associées permettant de sortir entre autres, par une conduite 34 un diesel de haute qualité, par la conduite 35 un naphta et par une conduite 36 la purge du résidu d'hydrocraquage. Habituellement, l'unité 32 comprend également une zone d'hydrotraitement avant hydrocraquage.

The plant according to the invention (FIG. 2B) comprises, in addition to that of the prior art (FIG. 2A), the hydrocracking unit 32 at moderate pressure which receives a light fraction obtained from the vacuum distillation fed into the reactor. The unit 32 comprises the reactor (s) or zone (s) of hydrocracking at moderate pressure and the associated separations making it possible to exit, inter alia, via a pipe 34 a high quality diesel, via the pipe 35. a naphtha and a line 36 purge the hydrocracking residue. Usually, the unit 32 also comprises a hydrotreatment zone before hydrocracking.

The hydrocracking residue can at least partly be sent to catalytic cracking (unit 28) but not required. The purge of the hydrocracking process is advantageously sent to the unit 28.

The recycling of the purged residue to the hydrocracking zone, or to the hydrocracking reactor also comprising the hydrotreatment zone is not shown here.

Recycling and venting in FCC can be done separately or together.

In the context of the process according to the invention, as illustrated for example in FIG. 2B with an FCC, during atmospheric distillation the cutting point for the distilled diesel cut (line 24) is chosen by the operator.

The atmospheric residue, which therefore contains at least a portion of the heavy atmospheric gas oil, is distilled under vacuum in at least a light fraction (distillate) and at least a heavy fraction (distillate), and a residue remains under vacuum.

Said light fraction to be treated by hydrocracking has a temperature T5 which is between 250 and 400oC and a temperature T95 which is at most 4700C. It is a light vacuum diesel fuel (LVGO). The final boiling point is chosen by the operator according to the column at his disposal and according to the valuation required by the products.

Said light fraction has the other characteristics of the hydrocarbon feeds treated by the process according to the invention and previously described.

In general, this light pressure hydrocracking vacuum distillate treatment can be implemented when the production and / or the quality of the diesel need to be increased, regardless of the type of treatment reserved for the distillate (s). heavy (s) and residue of vacuum distillation.

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In another embodiment, instead of fractioning the atmospheric residue into light (s) and heavy (s) fraction (s) by vacuum distillation, and sending the light fraction (s) into the hydrocracking, it takes (if the type of column allows) the heavy gas oil cut having substantially the same temperatures T5 and T95 at the atmospheric distillation. This mode is illustrated in FIG. 2C, where the markings of the preceding figures are recognized and where the charge at unit 32 is an atmospheric gas oil brought by line 37. In this figure, line 33 no longer exists. In this case, the residue The atmospheric boiling over the heavy gas oil is distilled under vacuum, the vacuum distillation also produces a residue and at least a vacuum distillate fraction here called heavy.

The vacuum distillation residue (line 38), which generally has a temperature T5 of at least 535 ° C, of at least 55 ° C. preferably, or even at least 56 ° C. or 57 ° C., may for example be subjected to visbreaking (shown in FIG. Figure 1) or a residue hydroconversion or coking.

In all cases, at least one so-called heavy vacuum distillate fraction, located between the light fraction, having a T95 temperature of at most 4700C, and the residue under vacuum, is subjected to catalytic cracking.

FIG. 3 represents an installation and a process in which the heavy fraction obtained from vacuum distillation and which is subjected to catalytic cracking, is, before said cracking, subjected to a hydrotreatment in an area 43. The references of the previous figures are taken over right here.

This hydrotreatment before the FCC takes place in the presence of at least one amorphous catalyst. All the conventional hydrotreatment catalysts can be used. Catalysts containing at least one non-noble group VIII element (Co, NI for example) and at least one element of the group VIS (Mo, W for example) deposited on a support preferably based on alumina or silica are mentioned. -alumina. The particularity of this step lies in its operating conditions: a hydrogen partial pressure between 25 and 90 bar, preferably less than 85 bar, or even lower than 80 bar, or even lower than 70 bar, and a temperature of 350.degree. 450 C, preferably 370-430 C adjusted so as to maintain a conversion of at least 10% and preferably less than 40% in products boiling below 350 C and preferably 15-30%.

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Il est ainsi produit un naphta (conduite 44) et un diesel (conduite 45) mais de qualité moyenne et destiné soit à un usage de fuel domestique soit au pool diesel.

It is thus produced a naphtha (pipe 44) and a diesel (pipe 45) but of average quality and intended either for use of domestic fuel oil or diesel pool.

The hydrotreated effluent then passes into the catalytic cracking unit 28.

FIG. 4 diagrammatically shows a contribution of heavy diesel fraction in the unit 32 where the hydrocracking is carried out at moderate pressure. In this embodiment, it is obtained in atmospheric distillation, in addition to the naphtha cuts (line 22), kerosene (line 23), a light diesel fraction LGO (line 46) and a heavy diesel fraction HGO (line 47). This heavy diesel fraction is sent to unit 32 where it will undergo hydrotreatment and then hydrocracking at moderate pressure.

Thus, the present application describes a process for the production of diesel and naphtha, the production of diesel being carried out by a moderate pressure hydrocracking process as explained above, and the production of naphtha being obtained essentially by catalytic cracking. . Preferably, the hydrocracking purge is sent by catalytic cracking.

A preferred embodiment of this type of process has been disclosed, but other embodiments, other arrangements of the methods for achieving the same purpose are possible.

To illustrate the interest of the invention, it is hereinafter encrypted the production of a current refining scheme, a current scheme for a production of diesel specifications 2005 and a scheme according to the invention. In the scheme of Figure 2A (current scheme specifications 2000) for a treatment of 10 Mt / yr of North Sea crude, we have (Figure 1).

- naphtha 3, 17 man-carburettor 0, 73 Mt / yr - Diesel 2, 32 Mt / yr - Domestic fuel 1, 5 man - Fuel from a residue 565OC + subjected to a visbreaking: 1.42 Mt / yr of fuel 40 cst (diluted by LCO and including slurry) The diesel has a cetane number of 49 and a sulfur content of 2100 ppm. To be in specification (51 cetane and 350 ppm sulfur), it must undergo a conventional desulfurization.

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Sans changement dans le schéma de raffinerie, mais avec des qualités diesel aux spécifications 2005 (point 95% pris à 3400C), on a (schéma 2) : - naphta 3,32 Mt/an - coupe carburéacteur 0,82 Mt/an - diesel 2, 13 man - Fuel domestique 1, 36 man - Fuel 40cst à partir du résidu 565OC+ 1,43 Mt/an Le diesel a un indice de cétane de seulement 48 et doit donc subir une hydrodésulfuration et une hydrogénation extrêmement sévères qu'il n'est pas possible de réaliser dans les unités actuelles.

No change in the refinery scheme, but with diesel qualities to the 2005 specifications (95% point taken at 3400C), we have (scheme 2): - naphtha 3.32 Mt / yr - carburettor fraction 0.82 Mt / y - diesel 2, 13 man - Domestic fuel 1, 36 man - Fuel 40cst from residue 565OC + 1.43 Mt / year The diesel has a cetane number of only 48 and must therefore undergo extremely severe hydrodesulfurization and hydrogenation it is not possible to perform in the current units.

The naphtha pool would have a sulfur content of 270 ppm, which would require severe subsequent treatments to reduce it to 10-50 mass ppm. To avoid costly investments, the naphtha fraction from the FCC will be treated separately in severe hydrodesulphurization, with the disadvantage of lowering the octane number. The other naphtha fractions (for example from the visbreductor, from the crude distillation) will be sent to the reforming and possibly an isomerization unit after hydrotreatment.

- naphta 3, 06 man - carburéacteur 0,84 Mt/an - diesel 2,57 Mt/an - fuel domestique 1,40 Mt/an - fuel 40 cst à partir du résidu 565OC+ 1,36 Mt/an Le cétane du diesel reste à environ 48. Le naphta de FCC a une teneur de 15 ppm en soufre, et dans le pool naphta la teneur en soufre peut alors être abaissée aussi bas que 5,5 ppm environ, et ce sans perte d'octane sensible. The addition to Scheme 2 preceding a hydrotreatment before catalytic cracking (as shown in FIG. 3 but under hydrocracking) has the consequence (Scheme 3):

- naphtha 3, 06 man - jet fuel 0.84 Mt / yr - diesel 2.57 Mt / yr - heating oil 1.40 Mt / yr - fuel oil 40 cst from residue 565OC + 1.36 Mt / yr Diesel cetane It remains at about 48. The FCC naphtha has a sulfur content of 15 ppm, and in the naphtha pool the sulfur content can then be lowered as low as about 5.5 ppm, without substantial loss of octane.

With a scheme 4 preferred according to the invention (Figure 3) including hydrocracking at moderate pressure, we obtain (scheme 4): - naphtha 2.90 Mt / year - carburetor 0.86 Mt / year - diesel 2.82 Mt / year - domestic fuel 1,44 Mt / yr

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- fuel 40 cst 1, 34 Mt/an Dans ce cas, la distillation sous vide sépare, une fraction légère 350-4100C, une fraction lourde 41 0-565OC et un résidu 565OC+.

In this case, the vacuum distillation separates, a light fraction 350-4100C, a heavy fraction 41 0-565OC and a residue 565OC +.

In hydrocracking, the conversion is almost complete (98%), the H2 consumption of 1.85% wt, the pressure is 90 bar ppH2.

La comparaison de ces chiffres montre l'excellente qualité du diesel obtenu par un schéma selon l'invention, qualité jamais atteinte directement auparavant. Diesel obtained point 95% 3400C flash point> 600C cetane 56 sulfur <10 ppm polyaromatic <1% wt

The comparison of these figures shows the excellent quality of the diesel obtained by a scheme according to the invention, quality never reached directly before.

Compared to conventional hydrocracking, for the same product qualities, it has been possible to achieve a saving of 50 bars in hydrogen pressure, which considerably lowers the costs.

In terms of productivity, the quantities of the products are similar to those of the diagram 3, but on the other hand the comparison with the diagram 2 (current refinery put in the specifications 2005) shows significant gains, for the same quantity of crude oil in: diesel + 32.4% kerosene 4.9% The diesel / naphtha balance could thus be adjusted to more high quality diesel, while reducing fuel oil production by some 40cst (-6.3%), adapting the refinery to the needs of the market. In addition, the FCC unit does not work at full capacity, the operator can very advantageously introduce a charge supplement able to be treated in FCC (such as an atmospheric residue). This addition will preferably be carried out in the feed entering the vacuum distillation column (dotted line in FIG. 3).

Claims (21)

80% volume and the liquid effluent obtained by hydrocracking being distilled to separate the diesel. T5 between 250 and 400 ° C. and a T95 temperature of at most 4700 ° C., said process comprising a hydrotreatment and then a hydrocracking at moderate pressure, said hydrocracking operating under a hydrogen partial pressure greater than 70 bar and at most 100 bar , at a temperature of at least 3200C, with a volume ratio H2 / load of at least 200 NI / NI, an hourly volume velocity of 0.15-7h-1, the process converting at least Claims 1 Process for producing a diesel having a distillation point 95% below 360 ° C, a sulfur content of at most 50 ppm and a cetane number greater than 51, said process treating hydrocarbon feeds having a temperature The process of claim 1 wherein the conversion is at least 95% volume. 3 Process according to one of the preceding claims wherein the hydrocarbon feed has a temperature Tgs between 390-430 C. 4 Process according to one of the preceding claims wherein the hydrocarbon feedstock has a temperature T5 between 320 and 3700C. 5. Method according to one of the preceding claims wherein the hydrocarbon feedstock is selected from the group consisting of heavy atmospheric gas oils or light fractions of gas oils in vacuo, the distillates in light voids, the mixtures of said charges together, mixtures said charges with a diesel fraction. 6. Method according to one of the preceding claims wherein the hydrotreating and hydrocracking are carried out in the same reactor and without intermediate separation of the gases produced by the hydrotreatment. Process according to one of the preceding claims, in which the hydrocracking residue is recycled after purging in the process. <Desc / Clms Page number 24>

8 Process according to one of the preceding claims wherein the diesel obtained has a 95% point of at most 3400C, a sulfur content of at most 10 ppm and cetane number of at least 54. Process according to one of the preceding claims, in which the filler having a temperature T5 of 250 to 4000 ° C and a temperature T95 of at most 47 ° C. is a light fraction originating from the vacuum distillation of an atmospheric residue. The process according to claim 9 wherein the vacuum distillation also produces a vacuum residue boiling at least 535 ° C and at least one heavy fraction between said light fraction and the residue, said heavy fraction being subjected to less in part, catalytic cracking. 11. Process according to one of the preceding claims, in which the hydrocarbon feedstock to be treated by moderate pressure hydrocracking is a heavy atmospheric atmospheric diesel fuel, the atmospheric residue boiling over said gas oil is distilled under vacuum, and at least one fraction Heavy vacuum distillate is catalytically cracked and a vacuum residue is obtained. Process according to one of the preceding claims, in which the purge of the hydrocracking at moderate pressure is subjected to catalytic cracking. Process according to one of the preceding claims, in which, before being subjected to catalytic cracking, the heavy vacuum distillate fraction is hydrotreated under a hydrogen partial pressure of 25-90 bar, at a temperature of

 temperature of 350-430 C, with a conversion of at least 10% and less than 40% volume in products boiling below 3500C. Process according to one of the preceding claims wherein the vacuum residue is subjected to a treatment by a process selected from the group consisting of visbreaking processes, residue hydroconversion processes, coking processes. Apparatus for the production of diesel comprising a distillation column of a hydrocarbon feedstock for separating at least one fraction having a temperature T5 of between 2500 ° C. and 4000 ° C. and a temperature T95 of at most 47 ° C. <Desc / Clms Page number 25>  at least one hydrotreatment zone of said feedstock or said fraction, at least one hydrocracking zone at moderate pressure of said fraction, said pressure being greater than 70 bars and at most 100 bars, at least one product separation zone to obtain a diesel having a distillation point 95% below 360 ° C, a sulfur content of not more than 50 ppm and a cetane number greater than 51.

16 Installation for the production of diesel according to claim 15, from a crude hydrocarbon feedstock comprising: - an atmospheric distillation column of said raw feedstock for separating at least naphtha, diesel and an atmospheric residue, a distillation column under vacuum to treat said atmospheric residue, and to separate at least one vacuum distillate fraction and a vacuum residue, - installation in which the atmospheric distillation column or the vacuum distillation column comprises at least one pipe recovering a fraction having a temperature T5 between 2500C and 4000C and a temperature T95 of at most 4700C, - the installation also comprises at least one hydrotrolement zone of said fraction followed by at least one hydrocracking zone at moderate pressure, and at least one product separation zone for obtaining a diesel having a distillation point 95% below 3600C, a sulfur content of not more than 50 ppm and a cetane number greater than 51. 17 Installation according to one of claims 15 or 16 comprising a hydrotreating zone before the hydrocracking zone and located in the same reactor. 18 Installation according to one of claims 15 to 17 wherein the zone of

 separation of the products separates a hydrocracking residue boiling point greater than at least 535OC, and comprises a purge pipe of said residue and optionally a recycle line of said purged residue to the zone or the hydrocracking reactor. 19 Apparatus according to one of claims 15 to 18 comprising a catalytic cracking zone for treating at least a fraction of vacuum distillate located between the fraction having a T95 temperature of at most 4700C and the residue under vacuum. <Desc / Clms Page number 26>

 20. Installation according to one of claims 15 to 19 comprising a pipe causing the purge to the catalytic cracking zone. Installation according to one of claims 15 to 20 comprising a hydrotreating zone before the catalytic cracking zone.