FR3091536A1 - ONE-STEP HYDROCRACKING PROCESS COMPRISING A HYDROGENATION STEP UPSTREAM OR DOWNSTREAM OF THE HYDROCRACKING STEP FOR THE PRODUCTION OF NAPHTA - Google Patents

Abstract

The present invention resides in the implementation of a one-step hydrocracking process for the production of naphtha, comprising a hydrogenation step placed downstream of said hydrocracking step or upstream of said hydrocracking step, on the loop for recycling the unconverted fraction, the hydrogenation step being carried out in the presence of a specific hydrogenation catalyst. In addition, the hydrogenation and hydrocracking stages are carried out under specific operating conditions and in particular under very specific temperature conditions. Figure 1 to publish.

Description

Description

Title of the invention: ONE-STEP HYDROCRACKING PROCESS COMPRISING A HYDROGENATION STEP UPSTREAM OR DOWNSTREAM OF THE HYDROCRACKING STEP FOR THE PRODUCTION OF NAPHTA

Technical area

The invention relates to a one-step hydrocracking process for eliminating heavy polycyclic aromatic compounds (HPNA) without reducing the yield of recoverable products.

Hydrocracking processes are commonly used in refineries to transform hydrocarbon mixtures into easily recoverable products. These methods can be used to transform light cuts such as, for example, essences into lighter cuts (LPG). However, they are usually rather used to convert heavier charges (such as heavy petroleum or synthetic cuts, for example gasoils from vacuum distillation or effluents from a Lischer-Tropsch unit) into petrol or naphtha, kerosene, diesel .

Certain hydrocracking processes also make it possible to obtain a highly purified residue which can constitute excellent bases for oils. One of the effluents particularly targeted by the hydrocracking process is the middle distillate (fraction which contains the diesel cut and the kerosene cut), that is to say cuts with an initial boiling point of at least 150 ° C. and with a final boiling point lower than the initial boiling point of the residue, for example less than 340 ° C, or even less than 370 ° C.

The Light Gasoline Cup (having an initial boiling point above 20 ° C and a final boiling point below 80 ° C), or "Light Naphtha" according to English terminology, and the Gasoline Cup Heavy (having an initial boiling point higher than 70 ° C and a final boiling point lower than 250 ° C), or "Heavy Naphta" according to English terminology, are also sought for uses in fuel bases or for petrochemicals, and certain hydrocracking processes are adapted to maximize the production of the “Heavy Naphtha” cut.

Hydrocracking is a process which derives its flexibility from three main elements which are, the operating conditions used, the types of catalysts used and the fact that hydrocracking of hydrocarbon feedstocks can be carried out in one or in two stages.

In particular, the hydrocracking of vacuum distillates or DSV makes it possible to produce light cuts (Gasoil, Kerosene, Naphtas, ...) more valuable than the DSV itself. This catalytic process does not entirely transform the DSV into light cuts. After fractionation, there remains a more or less significant proportion of fraction of unconverted DSV called UCO or UnConverted Oil according to the English terminology. To increase the conversion, this unconverted fraction can be recycled at the inlet of the hydrotreating reactor or at the inlet of the hydrocracking reactor in the case where it is a hydrocracking process in 1 step or at the inlet of a second hydrocracking reactor treating the fraction not converted at the end of the fractionation step, in the case where it is a hydrocracking process in 2 stages.

It is known that the recycling of said unconverted fraction from the separation step to the hydrocracking step of a one-step process leads to the formation of heavy aromatic (polycyclic) compounds called HPNA during the cracking reactions and thus to the undesirable accumulation of said compounds in the recycling loop, leading to the degradation of the performance of the hydrocracking catalyst and / or to its fouling. A purge is generally installed on the recycle of said unconverted fraction, in general on the line at the bottom of the fractionation, in order to deconcentrate the recycle loop into HPNA compounds, the purge flow being adjusted so as to balance their formation flow. In fact, the heavier the HPNA, the more they tend to stay in this loop, to accumulate, and to get heavier.

However, the conversion of a hydrocracking process in one step is directly linked to the quantity of heavy products purged at the same time as the HPNAs. This purge therefore leads to a loss of recoverable products which are also extracted with the HPNAs via this purge.

Depending on the operating conditions of the process, said purge can be between 0 and 10% by weight of the heavy fraction relative to the incoming DSV mother charge, and preferably between 0.5% and 5% by weight. The yield of recoverable products is therefore reduced accordingly, which constitutes a significant economic loss for the refiner.

Throughout the rest of the text, the HPNA compounds are defined as polycyclic or polynuclear aromatic compounds which therefore comprise several condensed benzene rings or rings. They are usually called PNA, Polynuclear Aromatics according to Anglo-Saxon terminology, for the lightest of them, and HPA or HPNA, Heavy PolyNuclear Aromatics according to Anglo-Saxon terminology, for compounds comprising at least seven aromatic rings (such as for example Coronene, compound with 7 aromatic rings). These compounds formed during undesirable side reactions, are stable and very difficult to hydrocrack. Prior art

There are various patents which relate to methods which seek to specifically address the problem associated with HPNAs so that they do not harm the method both in terms of performance, cycle time, and operability. .

Some patents claim the elimination of HPNA compounds by fractionation, distillation, solvent extraction or adsorption on a capture mass (WO2016 / 102302, US8852404 US9580663, US5464526 and US4775460).

Another technique consists in hydrogenating the effluents containing the HPNAs in order to limit their formation and accumulation in the recycle loop.

US Pat. No. 3,929,618 describes a process for hydrogenating and opening the hydrocarbon charge cycles containing polycyclic hydrocarbons condensed in the presence of a catalyst based on NaY zeolite and exchanged with Nickel.

The patent US4931165 describes a hydrocracking process in one step comprising a hydrocracking step followed by a step of separation of at least part of the unconverted heavy fraction which is sent to a stripper which allows to separate a liquid fraction enriched in HPNA and a fraction comprising traces of HPNA, hydrogen and hydrocarbons. This fraction comprising traces of HPNA is then sent in a hydrogenation stage before being recycled in the hydrocracking stage.

The patent US4618412 describes a hydrocracking process in one step in which the unconverted effluent from the hydrocracking step containing HPNA is sent in a hydrogenation step on a catalyst based on Iron and alkali or alkaline earth metals, at temperatures between 225 and 430 ° C before being recycled in the hydrocracking step.

The patent US5007998 describes a hydrocracking process in one step in which the unconverted effluent from the hydrocracking step containing HPNA is sent in a hydrogenation step on a zeolitic hydrogenation catalyst (zeolite with pore sizes between 8 and 15 A) also comprising a hydrogenation component and a clay.

US5139644 describes a process similar to that of US5007998 with coupling to a step of adsorption of HPNA on an adsorbent.

The research carried out by the applicant led him to discover an improved implementation of the hydrocracking process in one step which makes it possible to increase the cycle time of the process by limiting the deactivation of the hydrocracking catalyst. . Another advantage of the present invention makes it possible to minimize the purging and therefore to maximize the recoverable products and in particular the yield of naphtha.

The present invention lies in the implementation of a hydrocracking process in one step for the production of naphtha, comprising a hydrogenation step placed downstream of said hydrocracking step or upstream of said step d hydrocracking, on the recycling loop of the unconverted heavy fraction, the hydrogenation step being carried out in the presence of a specific hydrogenation catalyst. In addition, the hydrogenation and hydrocracking steps are carried out under specific operating conditions and in particular under very specific temperature conditions.

Summary of the invention

In particular, the present invention relates to a process for producing naphtha and in particular “heavy naphtha” from hydrocarbon feedstocks containing at least 20% by volume and preferably at least 80% by volume of compounds boiling over- above 340 ° C, said process comprising and preferably consisting of at least the following steps:

A) A step of hydrotreating said feeds in the presence of hydrogen and at least one hydrotreatment catalyst, at a temperature between 200 and 450 ° C, under a pressure between 2 and 25 MPa, at a space speed between 0.1 and 6 h ¹ and at a quantity of hydrogen introduced such that the volume ratio liter of hydrogen / liter of hydrocarbon is between 100 and 2000 NL / L, [0023] b) a hydrocracking step of at least part of the effluent from step a), hydrocracking step b) operating, in the presence of hydrogen and at least one hydrocracking catalyst, at a TRI temperature between 250 and 480 ° C, under a pressure between 2 and 25 MPa, at a space speed between 0.1 and 6 h ¹ and at a quantity of hydrogen introduced such as the volume ratio liter of hydrogen / liter of hydrocarbon is between 80 and 2000 NL / L,

C) a step of high pressure separation of the effluent from step g) of hydrogenation or from step b) of hydrocracking to produce at least one gaseous effluent and one liquid hydrocarbon effluent,

D) a distillation step of at least part of the liquid hydrocarbon effluent from step c) used in at least one distillation column, step from which it is withdrawn:

- a gaseous fraction,

- At least a fraction comprising the converted hydrocarbon products having at least 80% by volume of products boiling at a temperature below 250 ° C, preferably below 220 ° C, preferably below 190 ° C and more preferably below 175 ° C, and

- An unconverted liquid fraction having at least 80% by volume of products having a boiling point above 175 ° C, preferably above 190 ° C, preferably above 220 ° C and more preferred above 250 ° C,

E) optionally purging at least part of said unconverted liquid fraction containing HPNA, having at least 80% by volume of products having a boiling point above 175 ° C,

F) recycling at least a portion of said unconverted liquid fraction optionally purged, having a boiling point above 175 ° C, in step a) of hydrotreatment and / or in step b) hydrocracking,

G) a hydrogenation step, said step g) being carried out in the presence of hydrogen and a hydrogenation catalyst, at a temperature TR2 of between 150 and 470 ° C, under a pressure of between 2 and 25 MPa, at a space speed between 0.1 and 50 h ¹ and at a quantity of hydrogen introduced such that the volume ratio of liter of hydrogen / liter of hydrocarbon is between 100 and 4000 NL / L, said hydrogenation catalyst comprising at least one group VIII metal chosen from nickel, cobalt, iron, palladium, platinum, rhodium, ruthenium, osmium and iridium alone or as a mixture and a support chosen from refractory oxide supports, and in which the temperature TR2 is at least 10 ° C lower than the temperature TRI,

Said step g) of hydrogenation being placed

- either between said step b) of hydrocracking and said step c) of separation,

- or on said recycle loop of at least part of said unconverted liquid fraction from step d).

The temperature expressed for each step is preferably a weighted average temperature over all of the catalytic bed (s), or the WABT temperature according to English terminology, for example as defined in the book (Hydroprocessing of Heavy Oils and Residua, Jorge Ancheyta, James G. Speight 2007 - Science).

An advantage of the present invention is to provide a hydrocracking process in one step of a DSV charge making it possible both to maximize the overall yield of said so-called "heavy naphtha" cutting process and to increase the duration of process cycle by limiting deactivation of the hydrocracking catalyst. Purge can also be minimized, which maximizes the overall process conversion.

Throughout the rest of the text, the term "heavy naphtha" is understood according to English terminology, the heavy gasoline fraction resulting from atmospheric distillation at the outlet of the hydrocracker. Said fraction advantageously comprises at least 80% by volume of products boiling at a boiling temperature of between 70 and 250 ° C and preferably between 75 and 220 ° C, preferably between 80 and 190 ° C and more preferably between 80 and 175 ° C.

The term "light naphtha" fraction according to English terminology, the light gasoline fraction from atmospheric distillation at the outlet of

1‘cracker. Said fraction advantageously comprises at least 80% by volume of products boiling at a boiling temperature of between 20 and 80 ° C, preferably between 25 and 75 ° C and preferably between 30 and 70 ° C.

Charges

The present invention relates to a process for hydrocracking hydrocarbon feeds called mother feed, containing at least 20% by volume, and preferably at least 80% by volume, of compounds boiling above 340 ° C., preferably above 350 ° C and preferably between 350 and 580 ° C (that is to say corresponding to compounds containing at least 15 to 20 carbon atoms).

Said hydrocarbon feedstocks can advantageously be chosen from VGOs (Vacuum gas oil) according to English terminology or vacuum distillate (DSV) or gas oils, such as for example gas oils obtained from the direct distillation of crude oil or 'conversion units such as LCC (for example LCO or Light Cycle Oil according to English terminology), coking units or visbreaking as well as feeds from aromatic base extraction units lubricating oil or derived from solvent dewaxing of the lubricating oil bases, or still distillates originating from desulphurization or hydroconversion of RAT (atmospheric residues) and / or RSV (vacuum residues), or else the charge can advantageously be a deasphalted oil, or fillers from biomass or any mixture of the fillers previously mentioned and preferably VGOs.

Paraffins from the Lischer-Tropsch process are excluded.

The nitrogen content of the mother feeds treated in the process according to the invention is usually greater than 500 ppm by weight, preferably between 500 and 10,000 ppm by weight, more preferably between 700 and 4,000 ppm by weight and again more preferred between 1000 and 4000 ppm weight. The sulfur content of the mother feeds treated in the process according to the invention is usually between 0.01 and 5% by weight, preferably between 0.2 and 4% by weight and even more preferably between 0.5 and 3% weight.

The load can optionally contain metals. The cumulative nickel and vanadium content of the charges treated in the process according to the invention is preferably less than 1 ppm by weight.

The charge may optionally contain asphaltenes. The asphaltenes content is generally less than 3000 ppm by weight, preferably less than 1000 ppm by weight, even more preferably less than 200 ppm by weight.

In the case where the filler contains compounds of the resins and / or asphaltenes type, it is advantageous to pass the filler beforehand over a bed of catalyst or adsorbent different from the hydrocracking or hydrotreating catalyst.

Step a)

According to the invention, the method comprises a step a) of hydrotreating said charges in the presence of hydrogen and at least one hydrotreatment catalyst, at a temperature between 200 and 450 ° C, under a pressure between 2 and 25 MPa, at a space velocity between 0.1 and 6 h ¹ and at a quantity of hydrogen introduced such that the volume ratio liter of hydrogen / liter of hydrocarbon is between 100 and 2000 NL / L.

The operating conditions such as temperature, pressure, hydrogen recycling rate, hourly space velocity, may be very variable depending on the nature of the feed, the quality of the desired products and the facilities available to the refiner.

Preferably, step a) of hydrotreatment according to the invention operates at a temperature between 250 and 450 ° C, very preferably between 300 and 430 ° C, under a pressure between 5 and 20 MPa , at a space speed between 0.2 and 5 h ¹ , and at a quantity of hydrogen introduced such that the volume ratio of liter of hydrogen / liter of hydrocarbon is between 300 and 1500 NL / L.

Conventional hydrotreatment catalysts can advantageously be used, preferably which contain at least one amorphous support and at least one hydro-dehydrogenating element chosen from at least one element from the non-noble groups VIB and VIII, and most often at at least one element from group VIB and at least one element from group VIII which is non-noble.

Preferably, the amorphous support is alumina or silica-alumina.

Preferred catalysts are chosen from NiMo, NiW or CoMo catalysts on alumina and NiMo or NiW on silica-alumina.

The effluent from the hydrotreatment step and part of which enters step b) of hydrocracking generally comprises a nitrogen content preferably less than 300 ppm by weight and preferably less than 50 ppm by weight.

Step b)

According to the invention, the method comprises a step b) of hydrocracking at least part of the effluent from step a), and preferably all, said step b) operating, presence of hydrogen and at least one hydrocracking catalyst, at a temperature TRI between 250 and 480 ° C, under a pressure between 2 and 25 MPa, at a space speed between 0.1 and 6 h ¹ and to a quantity of hydrogen introduced such that the volume ratio liter of hydrogen / liter of hydrocarbon is between 80 and 2000 NL / L.

Preferably, step b) of hydrocracking according to the invention operates at a temperature between 320 and 450 ° C, very preferably between 330 and 435 ° C, under a pressure between 3 and 20 MPa , at a space speed between 0.2 and 4 h ¹ , and at a quantity of hydrogen introduced such that the volume ratio liter of hydrogen / liter of hydrocarbon is between 200 and 2000 NL / L.

In one embodiment making it possible to maximize the production of “heavy naphtha”, the operating conditions used in the process according to the invention generally make it possible to achieve conversions by pass, into products having at least 80% by volume of products having boiling points below 250 ° C, preferably below 220 ° C, preferably below 190 ° C, and more preferably below 175 ° C, above 15% by weight and even more preferred between 20 and 95% by weight.

The hydrocracking step b) according to the invention covers the pressure and conversion domains ranging from mild hydrocracking to high pressure hydrocracking. Mild hydrocracking is understood to mean hydrocracking leading to moderate conversions, generally less than 40%, and operating at low pressure, preferably between 2 MPa and 6 MPa. High pressure hydrocracking is generally carried out at higher pressures between 5 MPa and 25 MPa, so as to obtain conversions greater than 50%.

Step a) hydrotreating and step b) hydrocracking can advantageously be carried out in the same reactor or in different reactors. If they are produced in the same reactor, the reactor comprises several catalytic beds, the first catalytic beds comprising the hydrotreatment catalyst (s) and the following catalytic beds comprising the hydrocracking catalyst (s).

Catalyst from step b) of hydrocracking

According to the invention, step b) of hydrocracking operates in the presence of at least one hydrocracking catalyst.

The hydrocracking catalyst (s) used in hydrocracking step b) are conventional hydrocracking catalysts known to those skilled in the art, of bifunctional type combining an acid function with a hydro-dehydrogenating function and optionally at least one binding matrix. The acid function is provided by large surface supports (150 to 800 m2.g ¹ generally) having a surface acidity, such as halogenated aluminas (chlorinated or fluorinated in particular), combinations of boron and aluminum oxides, amorphous silica-aluminas and zeolites. The hydro-dehydrogenating function is provided by at least one metal from group VIB of the periodic table and / or at least one metal from group VIII.

Preferably, the hydrocracking catalyst (s) used in step b) comprise a hydro-dehydrogenating function comprising at least one group VIII metal chosen from iron, cobalt, nickel, ruthenium, rhodium , palladium and platinum, and preferably from cobalt and nickel. Preferably, the said catalyst (s) also comprise at least one metal from group VIB chosen from chromium, molybdenum and tungsten, alone or as a mixture, and preferably from molybdenum and tungsten. Hydro-dehydrogenating functions of the NiMo, NiMoW, NiW type are preferred.

Preferably, the metal content of group VIII in the hydrocracking catalyst (s) is advantageously between 0.5 and 15% by weight and preferably between 1 and 10% by weight, the percentages being expressed in weight percent of oxides relative to the total mass of catalyst.

Preferably, the metal content of group VIB in the hydrocracking catalyst (s) is advantageously between 5 and 35% by weight, and preferably between 10 and 30% by weight, the percentages being expressed as a percentage weight of oxides relative to the total mass of catalyst.

The hydrocracking catalyst (s) used in step b) can also optionally comprise at least one promoter element deposited on the catalyst and chosen from the group formed by phosphorus, boron and silicon, optionally at least one element from group VIIA (preferred chlorine, fluorine), optionally at least one element from group VIIB (preferred manganese), and optionally at least one element from group VB (preferred niobium).

Preferably, the hydrocracking catalyst (s) used in step b) comprise at least one porous amorphous or poorly crystallized mineral matrix of oxide type chosen from aluminas, silicas, silica-aluminas, aluminates, boron alumina-oxide, magnesia, silica-magnesia, zirconia, titanium oxide, clay, alone or as a mixture, and preferably aluminas or silica-aluminas, alone or mixed.

Preferably, the silica-alumina contains more than 50% by weight of alumina, preferably more than 60% by weight of alumina.

Preferably, the hydrocracking catalyst (s) used in step b) also optionally comprise a zeolite chosen from Y zeolites, preferably from US Y zeolites, alone or in combination, with other zeolites among the beta zeolites, ZSM-12, IZM-2, ZSM-22, ZSM-23, SAPO-11, ZSM-48, ZBM-30, alone or as a mixture. Preferably the zeolite is the USY zeolite alone.

In the case where said catalyst comprises a zeolite, the zeolite content in the hydrocracking catalyst (s) is advantageously between 0.1 and 80% by weight, preferably between 3 and 70% by weight, the percentages being expressed as a percentage of zeolite relative to the total mass of catalyst.

A preferred catalyst comprises and preferably consists of at least one group VIB metal and optionally at least one non-noble group VIII metal, at least one promoter element, and preferably phosphorus , at least one Y zeolite and at least one alumina binder.

An even more preferred catalyst comprises, and preferably consists of, nickel, molybdenum, phosphorus, a USY zeolite, and optionally also a beta zeolite, and alumina.

Another preferred catalyst comprises, and preferably consists of, nickel, tungsten, alumina and silica-alumina.

Another preferred catalyst comprises, and preferably consists of, nickel, tungsten, a USY zeolite, alumina and silica-alumina.

Step c)

According to the invention, the method comprises a step c) of high pressure separation of the effluent from step g) of hydrogenation or step b) of hydrocracking, to produce at least a gaseous effluent and a liquid hydrocarbon effluent.

In the case where step g) of hydrogenation is placed between said step b) of hydrocracking and said step c) of separation, the effluent entering step c) of separation is the effluent from of said step g) of hydrogenation.

In the case where step g) of hydrogenation is placed on said recycle loop f) of at least a portion of said unconverted liquid fraction from step d) of distillation, the effluent entering in step c) of separation is the effluent from said step b) of hydrocracking.

Said separation step advantageously comprises a separation means such as for example a series of high pressure separator flasks operating between 2 and 25 MPa, the aim of which is to produce a flow of hydrogen which is recycled via from a compressor to at least one of steps a), b) and / or g), and a hydrocarbon effluent which is preferably sent to a steam stripping step operating preferably at a pressure between 0.5 and 2 MPa, which aims to achieve a separation of hydrogen sulfide (H ₂ S) dissolved in at least said hydrocarbon effluent.

Step c) allows the production of a liquid hydrocarbon effluent which is then sent to step d) of distillation.

Step d)

According to the invention, the method comprises a step d) of distilling the effluent from step c) into at least one gaseous fraction comprising the light gases C1-C4, a fraction comprising the converted hydrocarbon products having at least 80% by volume, preferably at least 95% by volume, of products boiling at a temperature below 250 ° C, preferably below 220 ° C, preferably less than 190 ° C and more preferably below 175 ° C, and an unconverted liquid fraction having at least 80% by volume and preferably at least 95% by volume of products having a boiling point above 175 ° C, preferably above 190 ° C, more preferably greater than 220 ° C and more preferably greater than 250 ° C.

Fractions whose boiling point is between the boiling points of the "heavy naphtha" fraction and the unconverted fraction can also be separated.

Step e) optional

The method can optionally comprise a step e) of purging at least a portion of said unconverted liquid fraction containing HPNA, resulting from the distillation step d), preferably before its recycling in step a ) hydrotreatment and / or in step b) hydrocracking or its passage in step g) hydrogenation.

Said purge is between 0 to 10% by weight of the unconverted liquid fraction relative to the feedstock entering said process, and preferably between 0 to 5% by weight and very preferably between 0 and 3% by weight.

Step f)

According to the invention, the method comprises a step f) of recycling in said step a) of hydrotreatment and / or in said step b) of hydrocracking, of at least a part and preferably of the whole of said optionally purged unconverted liquid fraction, having at least 80% by volume of products having a boiling point above 175 ° C. This recycle stream can advantageously be introduced either upstream of step a) of hydrotreating, or upstream of step b) of hydrocracking.

Step g)

According to the invention, the method comprises a step g) of hydrogenation of heavy aromatic compounds, said step g) being carried out in the presence of hydrogen and a hydrogenation catalyst, at a temperature TR2 between 150 and 470 ° C, under a pressure between 2 and 25 MPa, at a space speed between 0.1 and 50 h ¹ and at a quantity of hydrogen introduced such as the volume ratio liter of hydrogen / liter of hydrocarbon is between 100 and 4000 NL / L, said hydrogenation catalyst comprising and preferably consisting of at least one metal from group VIII of the periodic table of elements chosen from nickel, cobalt, iron, palladium, platinum, rhodium, ruthenium, osmium and iridium, alone or as a mixture and of a support chosen from refractory oxide supports, and in which the temperature TR2 of step g) hydrogenation is at least 10 ° C lower than the TRI temperature of step b) hydrocracking, said step g) of hydrogenation being placed

- either between said step b) of hydrocracking and said step c) of separation,

- or on said recycle loop of at least part of said unconverted liquid fraction.

Preferably, said step g) of hydrogenation operates at a temperature TR2 between 150 and 380 ° C, preferably between 180 and 320 ° C, under a pressure between 3 and 20 MPa, and very preferably between 9 and 20 MPa, at a space speed between 0.2 and 10 h ¹ and at a quantity of hydrogen introduced such that the volume ratio liter of hydrogen / liter of hydrocarbon is between 200 and 3000 NL / L .

Preferably, the volume ratio of liter of hydrogen / liter of hydrocarbon in step g) is greater than that in step b) of hydrocracking.

Preferably, step g) is carried out at a temperature TR2 which is at least 20 ° C lower than the temperature TRI, preferably at least 50 ° C and preferably at least 70 ° C.

It is important to note that the temperatures TRI and TR2 are chosen in the intervals mentioned above so as to respect the temperature delta according to the present invention, namely that TR2 must be at least 10 ° C lower than the temperature TRI, preferably at least 20 ° C, preferably at least 50 ° C and even more preferably at least 70 ° C.

The technological implementation of step g) of hydrogenation is carried out according to any implementation known to a person skilled in the art, for example by injection, in ascending or descending current, of the hydrocarbon charge and hydrogen in at least one fixed bed reactor. Said reactor can be of the isothermal type or of the adiabatic type. An adiabatic reactor is preferred. The hydrocarbon charge can advantageously be diluted by one or more re-injection (s) of the effluent, coming from said reactor where the hydrogenation reaction takes place, at various points of the reactor, situated between the inlet and the outlet of the reactor in order to limit the temperature gradient in the reactor. The hydrogen flow can be introduced at the same time as the feed to be hydrogenated and / or at one or more different points of the reactor.

Preferably, the group VIII metal used in the hydrogenation catalyst is chosen from nickel, palladium and platinum, alone or as a mixture, and preferably nickel and platinum, alone or as a mixture. Preferably, said catalyst not comprising a group VIB metal and preferably said hydrogenation catalyst does not comprise molybdenum or tungsten.

In the case where said step g) of hydrogenation is placed between said step b) of hydrocracking and said step c) of separation, the hydrogenation catalyst preferably comprises a non-noble group VIII metal chosen from nickel, cobalt, and iron, alone or in admixture.

In the case where said step g) of hydrogenation is placed on the recycle loop f) of at least part of said unconverted liquid fraction, the hydrogenation catalyst preferably comprises a noble metal from group VIII chosen from palladium, platinum, rhodium, ruthenium, osmium and iridium, alone or as a mixture.

Preferably, when the metal of group VIII is a non-noble metal, preferably nickel, the content of metallic element of group VIII in said catalyst is advantageously between 5 and 65% by weight, more preferably between 8 and 55% by weight, and even more preferably between 12 and 40% by weight, and even more preferably between 15 and 30% by weight, the percentages being expressed as a percentage by weight of metallic element relative to the total mass of the catalyst. Preferably, when the group VIII metal is a noble metal, preferably palladium and platinum, the content of group VIII metal element is advantageously between 0.01 and 5% by weight, preferably between 0.05 and 3% by weight, and even more preferably between 0.08 and 1.5% by weight, the percentages being expressed as a percentage by weight of metallic element relative to the total mass of the catalyst.

Said hydrogenation catalyst can also comprise at least one additional metal chosen from group VIII metals, group IB metals and / or tin. Preferably, the additional metal from group VIII is chosen from platinum, ruthenium and rhodium, as well as palladium (in the case of a nickel-based catalyst) and nickel or palladium (in the case of '' a platinum-based catalyst). Advantageously, the additional metal of group IB is chosen from copper, gold and silver. The said additional metal (s) of group VIII and / or group IB is (are) preferably present in a content representing from 0.01 to 20% by weight of the mass of the catalyst, preferably from 0.05 to 10% by weight of the mass of the catalyst and even more preferably from 0.05 to 5% by weight of the mass of said catalyst. Tin is preferably present in a content representing from 0.02 to 15% by weight of the mass of the catalyst, so that the Sn / metal (ux) ratio of group VIII is between 0.01 and 0.2, preferably between 0.025 to 0.055, and even more preferably between 0.03 to 0.05.

The support for said hydrogenation catalyst is advantageously formed from at least one refractory oxide preferably chosen from metal oxides of groups IIA, IIIB, IVB, IIIA and IVA according to the CAS notation of the periodic classification of the elements. Preferably, said support is formed of at least one simple oxide chosen from alumina (A1 ₂ O ₃ ), silica (SiO ₂ ), titanium oxide (TiO ₂ ), cerine (CeO ₂ ) , zirconia (ZrO ₂ ) or P ₂ O ₅ . Preferably, said support is chosen from aluminas, silicas and silica-aluminas, alone or as a mixture. Very preferably, said support is an alumina or a silica-alumina, alone or as a mixture, and even more preferably an alumina. Preferably, the silica-alumina contains more than 50% by weight of alumina, preferably more than 60% by weight of alumina. Alumina can be present in all possible crystallographic forms: alpha, delta, theta, chi, rho, eta, kappa, gamma, etc., taken alone or as a mixture. Preferably, the support is chosen from delta, theta, gamma alumina.

The catalyst of step g) of hydrogenation may optionally comprise a zeolite chosen from Y zeolites, preferably USY zeolites, alone or in combination with other zeolites from beta, ZSM-12, IZM zeolites -2, ZSM22, ZSM-23, SAPO-11, ZSM-48, ZBM-30, alone or as a mixture. Preferably the zeolite is the USY zeolite alone.

Preferably, the catalyst of step g) does not contain a zeolite.

A preferred catalyst is a catalyst comprising, and preferably consisting of, nickel and alumina.

Another preferred catalyst is a catalyst comprising, and preferably consisting of, platinum and alumina.

Preferably, the catalyst of step g) of hydrogenation is different from that used in step a) of hydrotreatment and that used in step b) of hydrocracking.

According to the invention, said step g) of hydrogenation is placed:

- either between said step b) of hydrocracking and said step c) of separation,

- either on the recycle loop of at least part of said unconverted liquid fraction from step d), that is to say between said distillation step d) and either said step a) hydrotreatment or said step b) of hydrocracking.

In the case where said step g) of hydrogenation is placed between said step b) of hydrocracking and said step c) of separation, the charge of said step g) comprises and preferably consists of at least one part and preferably all of the effluent from said hydrocracking step b). In this case, it is the hydrogenated effluent from step b) of hydrocracking which is sent in part and preferably in whole in said step c) of separation. This case is said to be “downstream” because step g) of hydrogenation is placed downstream of said step b) of hydrocracking. In this case, the nitrogen content in step g), whether it is the organic nitrogen dissolved in the mother feed and in the unconverted heavy liquid fraction or the NH ₃ present in the gas phase depends mainly on the content of nitrogen in the mother charge. The partial pressure of NH ₃ in step g) and preferably greater than 200 ppm by weight, preferably greater than 500 ppm by weight ppm, more preferably greater than 1000 ppm by weight. In this case, the equivalent sulfur content is greater than 100 ppm by weight, preferably greater than 200 ppm by weight, more preferably greater than 500 ppm by weight.

In the case where said step g) of hydrogenation is placed on the recycling loop f) of at least part of said unconverted liquid fraction, said step g) is placed between said distillation step d) and either said step a) of hydrotreating or said step b) of hydrocracking.

In this case, the charge of said step g) comprises and preferably consists of at least part and preferably all of said unconverted liquid fraction, optionally purged. This case is said to be “upstream” because step g) of hydrogenation is placed upstream of said step b) of hydrocracking.

In this case, the nitrogen content in step g), whether the organic nitrogen dissolved in said unconverted liquid fraction or the NH ₃ present in the gas phase, is low, preferably less than 200 ppm by weight, preferably less than 100 ppm by weight, more preferably less than 50 ppm by weight. In this case, the partial pressure of H ₂ S of step g) is low, preferably the equivalent sulfur content is less than 800 ppm by weight, preferably between 10 and 500 ppm by weight, more preferably between 20 and 400 ppm weight

Step g) of hydrogenation can advantageously be carried out by using one or more hydrogenation catalysts, placed in the same reactor comprising one or more catalytic beds or in different reactors.

In the two alternatives according to the invention, “downstream” or “upstream” case, step b) of hydrocracking and step g) of hydrogenation can advantageously be carried out in the same reactor or in different reactors. If they are produced in the same reactor, the reactor comprises several catalytic beds,

The first catalytic beds comprising the hydrocracking catalyst (s) and the following catalytic beds (that is to say downstream) comprising the hydrogenation catalyst (s), in the “downstream” case,

The first catalytic beds comprising the hydrogenation catalyst (s) and the following catalytic beds (that is to say downstream) comprising the hydrocracking catalyst (s), in the "upstream" case.

In the “downstream” case, the temperature difference between the two stages b) of hydrocracking and g) of hydrogenation can be advantageously managed by one or more heat exchangers or by one or more quench (such as by example of hydrogen or liquid injection quench) in order to have a temperature of at least 10 ° C difference with the temperature of step b).

In the “upstream” case, the exotherm generated by step g) of hydrogenation advantageously helps to raise the temperature to reach the temperature of step b) of hydrocracking

The main objective of step g) of hydrogenation using a hydrogenation catalyst under operating conditions favorable to the hydrogenation reactions is to hydrogenate part of the aromatic or polyaromatic compounds contained in the feedstock entering said step and in particular to decrease the content of HPNA compounds. However, desulfurization, denitrogenation, olefin hydrogenation or mild hydrocracking reactions are not excluded. The conversion of aromatic or polyaromatic compounds is generally greater than 20%, preferably greater than 40%, more preferably greater than 60%, and particularly preferably greater than 80% of the aromatic or polyaromatic compounds contained in the feed entering in said step. The conversion is calculated by dividing the difference between the quantities of aromatic or polyaromatic compounds in the hydrocarbon charge and in the product by the quantities of aromatic or polyaromatic compounds in the hydrocarbon charge (the hydrocarbon charge being the incoming charge in said step g) of hydrogenation according to the two alternatives according to the invention, and the product being the effluent from step g).

In the presence of step g) of hydrogenation according to the invention, the hydrocracking process has an extended cycle time and / or an improved “heavy naphtha” yield List of figures

[0126] [fig. 1] Figure 1 illustrates the variant of the invention in which step g) of hydrogenation is placed downstream of step b) of hydrocracking.

The VGO type charge is sent via the line (1) in a step a) of hydrotreatment. The effluent from step a) is sent via line (2) in a hydrocracking step b). The effluent from step b) is sent via line (3) in a step g) of hydrogenation. The hydrogenated effluent from step g) is sent via line (4) in a step c) of high pressure separation to produce at least one gaseous effluent (not shown in the figure) and a liquid hydrocarbon effluent which is sent via line (5) in step d) of distillation. It is withdrawn from stage d) of distillation:

[0128] - a gaseous fraction (6),

- optionally a light gasoline fraction having at least 80% by volume of products having a boiling point of between 20 and 80 ° C, (7) and

- a fraction comprising the converted hydrocarbon products having at least 80% by volume of products boiling at a temperature below 250 ° C (8) and

[0131] - an unconverted liquid fraction having at least 80% by volume of products having a boiling point above 175 ° C (9)

At least part of the unconverted liquid fraction containing HPNA is purged via line (10).

The non-purged part (11) is recycled in step b) of hydrocracking.

[Fig-2] Figure 2 illustrates the variant of the invention in which step g) of hydrogenation is placed upstream of step b) of hydrocracking, on the recycle loop of the fraction unconverted liquid.

The VGO type charge is sent via the line (1) in a step a) of hydrotreatment. The effluent from step a) is sent via line (2) in a hydrocracking step b). The effluent from step b) is sent via line (3) in a step c) of high pressure separation to produce at least one gaseous effluent (not shown in the figure) and one liquid hydrocarbon effluent which is sent via line (4) in stage d) of distillation. It is withdrawn from stage d) of distillation:

A gas fraction (5),

- optionally a light petrol fraction having at least 80% by volume of products having a boiling point of between 20 and 80 ° C (6), and

- a fraction comprising the converted hydrocarbon products having at least 80% by volume of products boiling at a temperature below 250 ° C (7) and

[0139] - an unconverted liquid fraction having at least 80% by volume of products having a boiling point above 175 ° C (8)

At least part of the unconverted liquid fraction containing HPNA is purged via line (9).

The non-purged part (10) is sent to a hydrogenation g) before being recycled via the line (11) in step b) of hydrocracking.

Examples

Example No. 1 not in accordance with the invention: basic case of a one-step hydrocracking process not including a hydrogenation step

A hydrocracking unit processes a vacuum diesel fuel charge (VGO) described in Table 1:

[0145] [Tables 1]

Type VGO Debit t / h 37 Density - 0.91 Initial boiling point (PI TBP) ° c 297 Final boiling point (PP TBP) ° c 548 S content % wt 0.53 N content ppm wt 1146

Table 1

The VGO charge is injected in a preheating step then in a hydrotreatment reactor under the following conditions set out in Table 2:

[0148] [Tables2]

Reactor RA Temperature ° C 385 Total pressure MPa 14 Catalyst - NiMo on alumina WH h ¹ 1.67

Table 2

The effluent from this reactor is then injected into an RB hydrocracking reactor operating under the conditions of Table 3:

[0151] [Tables3]

Reactor RB Temperature (TRI) ° C 360 Total pressure MPa 14 Catalyst - Metal / zeolite WH h ¹ 1.5

Table 3

The RB effluent is then sent in a separation step composed of a heat recovery train then of high pressure separation including a recycle compressor and making it possible to separate on the one hand the hydrogen, the sulfide of hydrogen and ammonia and on the other hand the liquid hydrocarbon effluent supplying a stripper then an atmospheric distillation column in order to separate streams concentrated in H ₂ S, a light gasoline cut “Light Naphta” (of which 97% in volume of the compounds have a boiling point between 27 and 80 ° C), a heavy petrol cut “Heavy Naphta” (of which 96% by volume of the compounds have a boiling point between 80 and 175 ° C) and a unconverted liquid fraction (UCO) ”(of which 97% by volume of the compounds have a boiling point above 175 ° C). A purge corresponding to 3% by mass of the flow rate of the VGO charge is taken at the bottom of the distillation on the unconverted liquid fraction. The purged unconverted liquid fraction is then re-injected upstream of the RB hydrocracking reactor.

Example No. 2 in accordance with the invention:

Example 2 is in accordance with the invention insofar as it is a hydrocracking process in one step maximizing the production of the "Heavy" fraction

Naphtha "in which the effluent from the hydrocracking stage is sent to a hydrogenation stage in the presence of a hydrogenation catalyst comprising Ni and an alumina support and in which the temperature TR2 in stage d hydrogenation is at least 10 ° C lower than the TRI temperature in the hydrocracking step.

The hydrotreating steps in RA and hydrocracking in RB are carried out on the same charge and under the same conditions as in Example 1. A step of hydrogenation of the effluent from RB is carried out in an RH reactor downstream from RB. The operating conditions for RH are set out in Table 4. In this case, TR2 is 80 ° C lower than TRI.

[0157] [Tables4]

Reactor RH Temperature (TR2) ° C 280 Total pressure MPa 14 Catalyst - Ni / Alumina WH h ¹ 2

Table 4

The catalyst used in the RH reactor has the following composition: 28% w / w Ni on gamma alumina.

The hydrogenated effluent from RH is then sent to the high pressure separation step and then to the distillation step. A purge corresponding to 3% by mass of the flow rate of the VGO charge is taken at the bottom of the distillation on the unconverted liquid fraction. The purged unconverted liquid fraction is then re-injected upstream of the RB hydrocracking reactor.

Example No. 3 in accordance with the invention

Example 3 is in accordance with the invention insofar as it is a hydrocracking process in one step maximizing the production of the "Heavy Naphtha" fraction in which the effluent from the hydrocracking step is sent to a hydrogenation step in the presence of a hydrogenation catalyst comprising Ni and an alumina support and in which the temperature TR2 in the hydrogenation step is at least 10 ° C lower at the TRI temperature in the hydrocracking step.

The hydrotreatment steps in RA and hydrocracking in RB are carried out on the same charge and under the same conditions as in Example 1. A step of hydrogenation of the effluent from RB is carried out in an RH reactor downstream from RB. The operating conditions for RH are set out in Table 5. In this case, TR2 is 80 ° C lower than TRI.

[0164]

[Tables5]

Reactor RH Temperature (TR2) ° C 280 Total pressure MPa 14 Catalyst - Ni / Alumina WH h ¹ 2

Table 5

The catalyst used in the RH reactor has the following composition: 28% w / w Ni on gamma alumina.

The hydrogenated effluent from RH is then sent to the high pressure separation step and then to the distillation step. A purge corresponding to 1.5% by mass of the flow rate of the VGO charge is taken at the bottom of the distillation on the unconverted liquid fraction. The purged unconverted liquid fraction is then re-injected upstream of the RB hydrocracking reactor.

Example 0 conforming

Example 4 is in accordance with the invention insofar as it is a hydrocracking process in one step maximizing the production of the "Heavy Naphtha" fraction in which the unconverted liquid fraction from the distillation and purged is sent to a hydrogenation stage in the presence of a hydrogenation catalyst comprising Pt and an alumina support and in which the temperature TR2 in the hydrogenation stage is at least 10 ° C. lower at the TRI temperature in the hydrocracking step.

The hydrotreating steps in RA and hydrocracking in RB are carried out on the same charge and under the same conditions as in Example 1. A purge corresponding to 3% by mass of the flow rate of the VGO charge is taken at the bottom of the distillation on the unconverted liquid fraction.

The unconverted liquid fraction from the distillation and purged is sent in a hydrogenation step implemented in an RH reactor placed on the recycle mouth. This hydrogenation step is carried out in the presence of 20 ppm equivalent sulfur and 2 ppm equivalent nitrogen, which come from H ₂ S and NH ₃ present in the hydrogen and sulfur and nitrogen compounds still present in the liquid fraction. not converted. The operating conditions for RH are set out in Table 6. In this case, TR2 is 70 ° C lower than TRI.

[0172]

[Tablesô]

Reactor RH Temperature (TR2) ° C 290 Total pressure MPa 14 Catalyst - Pt / Alumina WH h ¹ 2

Table 6

The catalyst used in the RH reactor has the following composition: 0.3% by weight Pt on gamma alumina.

The hydrogenated effluent from RH is then re-injected upstream of the hydrocracking reactor RB.

Example No. 5 compliant

Example 5 is in accordance with the invention insofar as it is a hydrocracking process in one step maximizing the production of the "Heavy Naphtha" fraction in which the unconverted liquid fraction from the distillation and purged is sent to a hydrogenation stage in the presence of a hydrogenation catalyst comprising Pt and an alumina support and in which the temperature TR2 in the hydrogenation stage is at least 10 ° C. lower at the TRI temperature in the hydrocracking step.

The hydrotreatment steps in RA and hydrocracking in RB are carried out on the same charge and under the same conditions as in Example 1. This time, a purge corresponding to 1.5% by mass of the flow rate of the VGO charge is taken at the bottom of the distillation on the non-converted liquid fraction.

The unconverted liquid fraction from the distillation and purged is sent in a hydrogenation step implemented in an RH reactor placed on the recyle mouth. This hydrogenation step is carried out in the presence of 20 ppm equivalent sulfur and 2 ppm equivalent nitrogen, which come from H ₂ S and NH ₃ present in the hydrogen and sulfur and nitrogen compounds still present in the liquid fraction. not converted. The operating conditions for RH are set out in Table 7. In this case, TR2 is 70 ° C lower than TRI.

[0180]

[Paintings?]

Reactor RH Temperature (TR2) ° C 290 Total pressure MPa 14 Catalyst - Pt / Alumina WH h ¹ 2

Table?

The catalyst used in the RH reactor has the following composition: 0.3% wt wt on gamma alumina.

The hydrogenated effluent from RH is then re-injected upstream of the RB hydrocracking reactor.

Example 6: Performance of the process

Table 8 summarizes the performance of the processes described in Examples 1 to 5 in terms of yield in “Heavy Naphtha”, cycle time of the process and overall conversion of the process. The conversion of coronene (HPNA with 7 aromatic rings) carried out in the hydrogenation stage is also postponed.

[0186]

[Tables8]

Examples 1 (non-compliant ) 2 (consistent) 3 (consistent) 4 (compliant) 5 (consistent) Diagram RB alone RB + RH (downstream) RB + RH (downstream) RH + RB (upstream) RH + RB (upstream) Catalyst in R3 ___ 28% Ni / alumina 28% Ni / alumina 0.3% Pt / alumina 0.3% Pt / alumina Purge (%) 3 3 1.5 3 1.5 TRI (° C) 360 360 360 360 360 TR2 (° C) ___ 280 280 290 290 Coronene conversio n (%) (D 0 64 64 67 67 Yield in "Heavy Naphta" Based Based Base + 1.5 points Based Base + 1.5 points Cycle time Based Basic + 4 months Basic + 2 months Basic + 4 months Basic + 2 months Global Conversio n (%) 97 97 98.5 97 98.5

Table 8

The conversion of coronene is calculated by dividing the difference of the quantities of coronene measured upstream and downstream of the hydrogenation reactor by the amount of coronene measured upstream of this same reactor. The amount of coronene is measured by high pressure liquid chromatography coupled to a UV detector (HPLC-UV), at a wavelength of 302 nm for which the coronene has maximum absorption.

These examples illustrate the advantage of the method according to the invention which makes it possible to obtain improved performance in terms of cycle time, yield in “Heavy Naphtha”, or overall conversion of the method.

Claims (1)

[Claim 1] Claims Process for the production of naphtha from hydrocarbon feedstocks containing at least 20% by volume and preferably at least 80% by volume of compounds boiling above 340 ° C., said process comprising and preferably consisting of at least the steps following: a) A step of hydrotreating said feeds in the presence of hydrogen and at least one hydrotreatment catalyst, at a temperature between 200 and 450 ° C, under a pressure between 2 and 25 MPa, at a space speed between 0.1 and 6 h ¹ and at a quantity of hydrogen introduced such that the volume ratio liter of hydrogen / liter of hydrocarbon is between 100 and 2000 NL / L, b) a hydrocracking step at least part of the effluent from step a), step b) of hydrocracking operating, in the presence of hydrogen and at least one hydrocracking catalyst, at a temperature TRI between 250 and 480 ° C, under a pressure between 2 and 25 MPa, at a space velocity between be 0.1 and 6 h ¹ and at a quantity of hydrogen introduced such that the volume ratio of liter of hydrogen / liter of hydrocarbon is between 80 and 2000 NL / L, c) a step of high pressure separation of the effluent from step g) of hydrogenation or from step b) of hydrocracking to produce at least one gaseous effluent and one liquid hydrocarbon effluent, d) a step of distillation of at least part of l liquid hydrocarbon effluent from step c) used in at least one distillation column, step from which it is withdrawn: - a gaseous fraction, - at least a fraction comprising the converted hydrocarbon products having at least 80% by volume of products boiling at a temperature below 250 ° C, preferably below 220 ° C, preferably below 190 ° C and more preferably below 175 ° C, and - an unconverted liquid fraction having at least 80% by volume of products having a boiling point greater than 175 ° C, preferably greater than 190 ° C, preferably greater than 220 ° C and more preferably greater than 250 ° C, e) optionally purging at least a portion of said unconverted liquid fraction containing HPNA, having at least 80% by volume of products having a boiling point above 175 ° C, f) recycling at least part of said unconverted liquid fraction, optionally purged, having a boiling point above 175 ° C., in step a) of hydrotreatment and / or in step b) d hydrocracking, g) a hydrogenation step, said step g) being carried out in the presence of hydrogen and a hydrogenation catalyst, at a temperature TR2 of between 150 and 470 ° C, under a pressure of between 2 and 25 MPa, at a space speed between 0.1 and 50 h ¹ and at a quantity of hydrogen introduced such that the volume ratio of liter of hydrogen / liter of hydrocarbon is between 100 and 4000 NL / L, said hydrogenation catalyst comprising at least one group VIII metal chosen from nickel, cobalt, iron, palladium, platinum, rhodium, ruthenium, osmium and iridium alone or as a mixture and a support chosen from refractory oxide supports, and in which the temperature TR2 is at least 10 ° C lower than the temperature re TRI, said step g) of hydrogenation being placed - either between said step b) of hydrocracking and said step c) of separation, - or on said recycle loop of at least part of said unconverted liquid fraction from from step d). [Claim 2] Process according to Claim 1, in which the said hydrocarbon feedstocks are chosen from VGOs according to English terminology or vacuum distillates (DSV) or gas oils, such as gas oils obtained from the direct distillation of crude oil or from conversion units such as LCC, coking or visbreaking units as well as feeds from aromatic extraction units from lubricating oil bases or from solvent dewaxing of lubricating oil bases, or from distillates from desulfurization or hydroconversion of RAT (atmospheric residues) and / or RSV (vacuum residues), or among deasphalted oils, or fillers from biomass or any mixture of the fillers previously mentioned. [Claim 3] Process according to either of Claims 1 and 2, in which the hydrotreatment stage a) operates at a temperature between 300 and 430 ° C, under a pressure between 5 and 20 MPa, at a space speed between 0, 2 and 5 h *, and at a quantity of hydrogen introduced such that the volume ratio liter of hydrogen / liter of hydrocarbon is between 300 and 1500 NL / L. [Claim 4] Method according to one of claims 1 to 3 in which the hydrocracking step b) operates at a temperature between 330 and 435 ° C, under a pressure between 3 and 20 MPa, at a space speed between 0, 2 and 4 h ¹ , and at a quantity of hydrogen introduced such that the volume ratio liter of hydrogen / liter of hydrocarbon is between 200 and 2000 NL / L. [Claim 5] Method according to one of claims 1 to 4 wherein it is withdrawn from step d) of distillation at least a fraction comprising the converted hydrocarbon products having at least 80% by volume of products boiling at a temperature below 190 ° C , and an unconverted liquid fraction having at least 80% by volume of products having a boiling point above 190 ° C. [Claim 6] Method according to one of claims 1 to 5 wherein it is withdrawn from step d) of distillation at least a fraction comprising the converted hydrocarbon products having at least 80% by volume of products boiling at a temperature below 175 ° C, and an unconverted liquid fraction having at least 80% by volume of products having a boiling point above 175 ° C. [Claim 7] Process according to one of Claims 1 to 6, in which the said hydrogenation step g) operates at a temperature TR2 of between 180 and 320 ° C, under a pressure of between 9 and 20 MPa, at a space speed of between 0 , 2 and 10 h ¹ and at a quantity of hydrogen introduced such that the volume ratio liter of hydrogen / liter of hydrocarbon is between 200 and 3000 NL / L. [Claim 8] Method according to one of claims 1 to 7 wherein step g) is carried out at a temperature TR2 at least 20 ° C lower than the temperature TRI. [Claim 9] The method of claim 8 wherein step g) is carried out at a temperature TR2 at least 50 ° C lower than the temperature TRI. [Claim 10] The method of claim 9 wherein step g) is carried out at a temperature TR2 at least 70 ° C lower than the temperature TRI. [Claim 11] Method according to one of claims 1 to 10 wherein, in the case where said step g) of hydrogenation is placed between said step b) of hydrocracking and said step c) of separation, the charge of said step g) comprises at least part and preferably all of the effluent from said hydrocracking step b). [Claim 12] Method according to one of claims 1 to 10 wherein in the case where said step g) of hydrogenation is placed on the recycle loop of at least part of said unconverted liquid fraction, said step g) is placed between said distillation step d) and either said step a) of hydrotreatment or said step b) of hydrocracking, and the feed of said step g) comprises at least part and preferably all of said liquid fraction not converted, optionally purged. [Claim 13] Process according to one of Claims 1 to 12, in which the hydrogenation stage g) is carried out in the presence of a catalyst comprising, and preferably consisting of, nickel and alumina. [Claim 14] Process according to one of Claims 1 to 12, in which the hydrogenation stage g) is carried out in the presence of a catalyst comprising, and preferably consisting of, platinum and alumina. 1/1