FR3083243A1 - INTEGRATED TWO-STEP HYDROCRACKING PROCESS AND A REVERSE HYDROGEN CIRCULATION HYDROTREATING PROCESS - Google Patents

Abstract

The invention relates to an integrated hydrocracking and hydrotreatment process for DSV and diesel type hydrocarbon feedstocks, implemented in two stages and with reverse hydrogen circulation. The invention allows the production of middle distillates with improved process efficiency and comprises a) hydrocracking (A) of said charges (1) operating, in the presence of a hydrogen flow (18) coming from step g) of gas / liquid separation (G) and at least one hydrocracking catalyst, b) gas / liquid separation (B) of the effluent from step a) (3) to produce a liquid effluent (4) and a gaseous effluent comprising at least hydrogen (20), c) sending the gaseous effluent comprising at least hydrogen (20) in a compression step (C) before its recycling (21) into hydrocracking stage e), d) fractionation (D) of the liquid effluents from stages a) (5) and e) (19) into at least one effluent comprising the converted hydrocarbon products having lower boiling points at 340 ° C (7) (8) (9) and an unconverted liquid fraction (10), e) hydrocracking (E) of said unconverted liquid fraction from step d) (12) op being, in the presence of a flow of hydrogen coming from step c) of compression (21) and of a hydrocracking catalyst, f) hydrotreating (F) of the effluent coming from step e ) (14) mixed with a liquid hydrocarbon feedstock of the diesel fuel type (15), g) the gas / liquid separation (G) of the effluent from step f) (17) to produce a liquid effluent (19) and a gaseous effluent comprising at least hydrogen (18), said gaseous effluent (18) being directed to step a) of hydrocracking in order to provide the cover and the necessary hydrogen makeup.

Description

Field of the invention

Hydrocracking of heavy petroleum fractions is a key refining process which makes it possible to produce, from excess heavy and little recoverable charges, the lighter fractions such as gasolines, jet fuels and light gas oils that the refiner seeks to adapt its production to the request. Certain hydrocracking processes also make it possible to obtain a highly purified residue which can constitute excellent bases for oils or a feedstock which can easily be recovered in a catalytic cracking unit for example. One of the effluents particularly targeted by the hydrocracking process is the middle distillate (fraction which contains the diesel cut and the kerosene cut).

The hydrocracking process of vacuum distillates or DSV makes it possible to produce light cuts (Diesel, Kerosene, naphthas, ...) 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 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. The recycling of the fraction that is not converted at the inlet of the hydrotreatment reactor or at the inlet of the hydrocracking reactor makes it possible both to increase the conversion, but also makes it possible to increase the selectivity in gasoil and kerosene. Another way to increase the conversion while maintaining the selectivity is to add a conversion or hydrocracking reactor on the recycle loop from the unconverted fraction to the high pressure separation section. This reactor and the associated recycle constitutes a second hydrocracking step. This reactor being located downstream of the fractionation section, it operates with little sulfur (H ₂ S) and little nitrogen, which makes it possible to possibly use catalysts less sensitive to the presence of sulfur by increasing the selectivity of the process.

The diesel hydrodesulfurization process makes it possible to reduce the amount of sulfur contained in a diesel cut while minimizing the conversion of the charge into lighter products (gas, naphtha). The charge for hydrodesulfurization can consist of straight run diesel fuel according to English terminology or diesel fuel resulting from the atmospheric fractionation of crude oil, Light Vacuum Gasoil Oil according to English terminology or light vacuum distillate, LCO or distillate from a conversion process (FCC, coker or coking process, unit for converting residues into a bubbling bed of H-Oii type, etc.), from a diesel feedstock resulting from the conversion of biomass (esterification for example), alone or as a mixture, for example.

The partial pressure of hydrogen required for this process is lower than the partial pressure of hydrogen in the hydrocracker. It is common for these two processes to be present in the same refinery without being integrated. However, they are based on very similar process diagrams, consisting of a charging furnace, fixed bed reactors, hydrogen recycle compressors, and more or less complex high pressure separation sections.

The invention consists on the one hand in integrating a hydrocracking of vacuum distillates in two stages with a hydrodesulfurization of gas oils and on the other hand in operating a reverse hydrogen circulation within said integrated complex. The integration of the reaction sections is based on the use of a part of the reactor of the second hydrocracking stage to desulfurize the diesel feedstock in mixture with the effluent of the second hydrocracking stage. The invention allows a significant gain on the number of equipment, the size of the equipment and on investment.

Prior art

In a middle distillate production complex according to the prior art, consisting of a hydrocracking unit of vacuum distillates and of hydrotreating diesel fuel operating separately, each unit has its own recycle compressor.

In particular, within the two-stage hydrocracking process, the recycle compressor provides two hydrogen blankets, one dedicated to the first step and the other dedicated to the second step. The effluents from steps 1 and 2 are mixed and then directed to a high pressure gas / liquid separation section common to the two steps. The separated and hydrogen-rich gas flow has a substantial flow rate. It constitutes the recycle gas for the hydrocracking unit.

Conventionally, the complex therefore comprises two recycle compressors: the first sees the hydrogen blanket circulating necessary for the hydrotreatment of diesel, the second sees two hydrogen blankets circulating each necessary for one or the other step of the hydrocracking of DSV.

US Patent 5,958,218 A describes two units for processing hydrocarbon cuts operating in parallel and with a circulation of hydrogen in series between said units. More particularly, the invention describes a treatment complex operating in two stages, with separation / fractionation sections of the effluents shared between these stages. The circulation of hydrogen in series consists in mixing a flow of rich hydrogen coming from the recycle compressor of the complex with the charge of the second stage, itself coming from the fractionation column. The effluent from the second stage is directed to a separator flask to form on the one hand a gas stream rich in hydrogen, on the other hand a hydroprocessed liquid fraction. The gas stream from this separator is mixed with the hydrocarbon feed from the first step. The effluent from the first stage is directed to a separator to form a gas stream rich in hydrogen and a hydroprocessed liquid fraction. This hydrogen-rich gas flow is mixed with a make-up of hydrogen and, after compression, constitutes the recycle gas of the complex which feeds the second stage. The hydroprocessed liquid fractions from the two stages are fractionated in a pooled column.

The applicant’s research work led me to discover that it is possible to limit ourselves to a single recycle compressor with reduced flow for the entire complex. The invention is based on a reverse hydrogen circulation applied to an integrated hydrocracking unit for vacuum distillates and hydrotreating diesel oils. The advantages of the invention, compared to the processes dedicated to the hydrocracking of a distillate feed under vacuum and to the hydrodesulfurization of gas oils operating separately, are:

- Limit the number of equipment, and in particular reduce the number of hydrogen compressors;

- Reduce the design capacity of the recycle compressor of the integrated complex without degrading the hydrogen coverage of each of the reaction sections;

· Reduce the design capacity of high pressure equipment in the effluent separation section:

- Reduce the initial investment;

- Improve the overall efficiency of the process.

Summary of the invention

The present invention relates to an integrated two-stage hydrocracking process for a vacuum distillate charge and to hydrotreatment of a diesel charge, with reverse hydrogen circulation.

In particular, the present invention relates to a process for hydrocracking 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 following steps:

a) The hydrocracking of said charges operating, in the presence of a gaseous effluent comprising at least hydrogen coming from the separation step g) and at least one hydrocracking catalyst, at a temperature between 250 and 480 ° 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 as the volume ratio liter of hydrogen / liter of hydrocarbon either between 100 and 2000 L / L,

b) The gas / liquid separation of the effluent from step a) to produce a liquid effluent and a gaseous effluent comprising at least hydrogen,

c) The sending of the gaseous effluent comprising at least hydrogen in a compression stage before its recycling in the second hydrocracking stage e),

d) The fractionation of the liquid effluent from step b) of separation and the liquid effluent from step g) of separation into at least one effluent comprising the converted hydrocarbon products having lower boiling points at 340 ° C and an unconverted liquid fraction having a boiling point above 340 ° C,

e) Hydrocracking of at least a portion of said unconverted liquid fraction from step d) of operating fractionation, in the presence of at least a portion of the gaseous effluent comprising at least hydrogen from step c) of compression and of a hydrocracking catalyst, at a 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 to a quantity of hydrogen introduced such that the volume ratio of liter of hydrogen / liter of hydrocarbon is between 100 and 2000 L / L,

f) The hydrotreatment of the effluent from step e) in mixture with a liquid hydrocarbon feed comprising at least 95% by weight of boiling compounds at a boiling temperature between 150 and 400 ° C, said efeipe f) hydrotreatment operating in the presence of hydrogen and at least one hydrotreatment catalyst, at a temperature between 200 and 390 ° C, under a pressure between 2 and 16 MPa, at a space velocity between 0.2 and 5 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 L / L,

g) The gas / liquid separation of the effluent from step f) of hydrotreatment to produce a liquid effluent and a gaseous effluent comprising at least hydrogen and the sending of said gaseous effluent to the first step a) hydrocracking.

An advantage of the present invention is to provide an integrated process allowing the treatment of a charge of vacuum distillates and a charge of diesel oils within the same unit. The integration is based on a co-treatment of the effluent from the second hydrocracking step e) in admixture with a liquid hydrocarbon feedstock of the gas oil type preferably external to said process according to the invention, in a step f) of hydrotreatment, downstream of the hydrocracking step e) and allows a significant reduction in the number of equipment while retaining the selectivity for middle distillates. In particular, the invention makes it possible to limit itself to a single recycle compressor for the entire complex.

Another advantage of the present invention, obtained by the reverse circulation of hydrogen, is to greatly reduce the flow rate of the flow of hydrogen flowing through said compressor without degrading the hydrogen cover of the reaction sections. The invention thus allows a reduction in the dimensioning capacity of certain equipment, more particularly that of the recycle compressor and of the equipment contained in the high pressure separation section of the hydrogen loop.

Another advantage of the present invention is to provide a complex which by the integration of two processes allows the reduction of the initial investment cost and an improvement of the overall efficiency of the process.

Detailed description of the invention

Step a)

According to the invention, the method comprises a step a) of hydrocracking said operating charges, in the presence of a gaseous effluent comprising at least hydrogen from step g) of gas / liquid separation and at least one hydrocracking catalyst, at a temperature between 250 and 480 ° 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 L / L.

Given the reverse mode of circulation of hydrogen, the volume ratio will result from the volume ratio implemented in the second hydrocracking step e).

The operating conditions such as temperature, pressure, hydrogen recycling rate, hourly space velocity, can 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 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, and very preferably between 6 and 20 MPa, at a space speed of between 0.2 and 4 h -1, very preferably between 0.3 and 5 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 L / L.

These operating conditions used in step a) of the process according to the invention generally make it possible to achieve conversions by pass, into products having boiling points below 340 ° C, and better still below 370 ° C, greater than 15% by weight and even more preferably between 20 and 95% by weight.

In accordance with the invention, the hydrocarbon feedstocks treated in the process according to the invention and sent in step a) are chosen from hydrocarbon feedstocks containing at least 20% by volume and preferably at least 80% by volume of boiling compounds. above 340 ° C and preferably between 370 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 Anglo-Saxon or vacuum distillate (DSV) terminology such as for example gas oils obtained from the direct distillation of crude oil or from conversion units such as FCC, coker (or coking process) or visbreaking as well as fillers from aromatic extraction units from lubricating oil bases or from solvent dewaxing of lubricating oil bases, or from distillates from desulphurization or hydroconversion of RAT (atmospheric residues) and / or RSV (residues under vacuum), or the feed can advantageously be a deasphalted oil, or fillers from biomass or any mixture of the fillers previously mentioned . The above list is not exhaustive. In general, said fillers have an initial boiling point greater than 340 ° C, and preferably greater than 370 ^!> C.

Said hydrocarbon feedstocks can contain heteroatoms such as sulfur and nitrogen. The nitrogen content is usually between 1 and 8000 ppm by weight, more generally between 200 and 5000 ppm by weight, and the sulfur content between 0.01 and 6. % by weight, more generally between 0.2 and 5% and even more preferably between 0.5 and 4% by weight.

Said charge treated in the process according to the invention and sent in step a) may possibly contain metals. The cumulative nickel and vanadium content of the charges treated in the processes according to the invention is preferably less than 1 ppm by weight.

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

According to the invention, the hydrocracking step a) operates in the presence of at least one hydrocracking catalyst. Preferably, the hydrocracking catalyst is chosen from the conventional hydrocracking catalysts known to those skilled in the art.

The hydrocracking catalysts used in hydrocracking processes are all of the bifunctional type combining an acid function with a hydrogenating function. The acid function is provided by supports of large surfaces (150 to 800 m ² .g-1 generally) having a surface acidity, such as halogenated aluminas (chlorinated or fluorinated in particular), combinations of boron oxides and aluminum, amorphous silica-aluminas and zeolites. The hydrogenating function is provided either by one or more metals from group VIII of the periodic table, or by a combination of at least one metal from group VIB of the periodic table and at least one metal from group VIII.

Preferably, the hydrocracking catalyst or catalysts comprise a hydrogenating function comprising at least one metal from the HIV group chosen from iron, cobalt, nickel, ruthenium, rhodium, palladium and platinum and preferably cobalt and nickel and / or at least one metal from group VIB chosen from chromium, molybdenum and tungsten, alone or as a mixture and preferably from molybdenum and tungsten.

Preferably, the metal content of the HIV group in the hydrocracking catalyst (s) is advantageously between 0.5 and 15% by weight and preferably between 2 and 10% by weight, the percentages being expressed as percentage by weight of oxides.

Preferably, the content of group VIB metal in the hydrocracking catalyst (s) is advantageously between 5 and 25% by weight and preferably between 15 and 22% by weight, the percentages being expressed as percentage by weight of oxides.

The catalyst (s) can also optionally 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 the HAV group (chlorine, fluorine preferred), and optionally at at least one element from group VIIB (preferred manganese), optionally at least one element from group VB (preferred niobium).

Preferably, the hydrocracking catalyst (s) comprise an acid function chosen from alumina, silica alumina and zeolites, preferably chosen from zeolites Y and preferably chosen from silica alumina and zeolites.

A preferred catalyst comprises and preferably consists of at least one group VI metal and / or at least one non-noble group VIII metal, and a zeolite Y and an alumina binder.

An even more preferred catalyst comprises and preferably consists of nickel, molybdenum, a Y zeolite and alumina.

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

In stage a) of the process according to the invention, the conversion, during the first stage, into products having boiling points below 340 ° C., better still below 370 ° C., is greater than 20% and preferably greater than 30% and even more preferably between 30 and 80% and preferably between 40 and 60%.

The hydrocarbon feedstocks treated in the process according to the invention and sent in step a) can optionally be sent in a hydro-treatment step before being sent in step a) of hydrocracking of said process. In the optional hydrotreatment step, said feeds are advantageously desulfurized and denitrogenated.

Preferably, said hydrotreatment step is advantageously carried out under standard hydrorefining conditions and in particular in the presence of hydrogen and a hydrotreatment catalyst and at a temperature between 200 and 400 ° C., under a pressure between 2 and 16 MPa, at a space velocity between 0.2 and 5 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 L / 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 BIV and HIV groups, and most often at least one element of the VIB group and at least one element of the non-noble VIil group.

Preferably, the amorphous support is alumina or silica alumina.

Preferred catalysts are chosen from NiMo catalysts on alumina and NiMo or NIW catalysts on silica alumina.

The effluent resulting from the hydrotreatment step and entering step a) of hydrocracking comprises a nitrogen content preferably less than 300 ppm by weight and preferably less than 50 ppm by weight.

In the case where a hydrotreatment step is implemented, the hydrotreatment step and the hydrocracking step a) can advantageously be carried out in the same reactor or in different reactors. In the case where 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).

Step b)

According to the invention, the method comprises a step b) of gas / liquid separation of the effluent from step a) to produce a liquid effluent and a gaseous effluent comprising at least hydrogen.

Preferably, step b) of gas / liquid separation is implemented in a high pressure high temperature separator operating at a temperature between 50 and 450 ° C, preferably between 100 and 400 ° C, even more preferably between 200 and 300 ° C, and a pressure corresponding to the outlet pressure of a) minus the pressure drops.

Step c)

According to the invention, the method comprises a step c) of sending the gaseous effluent comprising at least hydrogen from step b) of separation in a compression step before its recycling, preferably at least partly and preferably entirely, in the second hydrocracking step e). This step is necessary to allow recycling of the gas upstream, that is to say in step e) of hydrocracking, therefore at higher pressure.

The gaseous effluent comprising at least hydrogen from step b) of separation can advantageously be mixed with make-up hydrogen before or after its introduction into step c) of compression, preferably via a make-up or make-up hydrogen compressor according to Anglo-Saxon terminology.

Optionally, part of the gaseous effluent comprising at least compressed hydrogen from step c) can also advantageously be sent between the catalytic beds of the reactor or reactors in step a) of hydrocracking in order to carry out the hydrocracking reaction quench. According to another option, these same quenches can be supplied with part of the hydrogen-rich gaseous effluent obtained in step g) of gas / liquid separation.

Step d)

According to the invention, the method comprises a step d) of fractionation of the liquid effluent from step b) of separation and of liquid effluent from step g) of separation into at least one effluent comprising the products converted hydrocarbons having boiling points below 340 ° C, preferably below 370 ° C and preferred boiling point below 380 ° C and an unconverted liquid fraction having a boiling point above 340 ° C, preferably higher at 370 ° C and preferably higher than 380 ° C also called UCO or "unconverted oii" according to English terminology.

Preferably, the liquid effluent from step b) of separation and the liquid effluent from step g) of separation are mixed upstream of step d) of fractionation.

Preferably, said step d) of fractionation comprises a first separation step comprising a separation means such as for example a separator flask or a steam stripper preferably operating at a pressure between 0.5 and 2 MPa, which aims to achieve a hydrogen sulfide (H ₂ S) separation from at least one hydrocarbon effluent produced during stages a) and e) of hydrocracking and during stage f) of hydrotreatment. The hydrocarbon effluent from this first separation can advantageously undergo atmospheric distillation, and in certain cases the combination of atmospheric distillation and vacuum distillation. The purpose of distillation is to produce a separation between the converted hydrocarbon products, that is to say generally having boiling points below 340 ° C, preferably below 370 ° C and preferably below 38 ° C and an unconverted liquid fraction (residue) (UCO).

According to another variant, the fractionation step consists only of an atmospheric distillation column.

The converted hydrocarbon products having boiling points below 340 ° C, preferably below 370 ° C and preferably below 380 ° C are advantageously distilled at atmospheric pressure to obtain several fractions converted at boiling point of at least plus 340 ° C, and preferably a light gas fraction C1 -04, at least a petrol fraction and at least a medium distillate kerosene and diesel fraction.

The liquid fraction, unconverted residue (UCO) containing products whose boiling point is greater than 340 ° C, preferably greater than 370 ° C, preferably greater than 380 ° C and resulting from distillation is at least partly and preferably entirely introduced in the second hydrocracking step e) of the process according to the invention.

A purge can advantageously be carried out on the residual liquid fraction in order to avoid the accumulation of heavy polyaromatic products (HPNA) present in the loop for recycling heavy cuts. Indeed, the HPNA gradually forms during their recycling in the second hydrocracking step and the recycling of these heavy aromatic components in the loop of the second hydrocracking step e) has the consequence of increasing their molecular weight. The presence of HPNA in said recycle loop ultimately leads to a significant pressure drop. A purge is therefore necessary in order to limit the accumulation of these HPNA products.

Step e)

According to the invention, the method comprises a second step e) of hydrocracking at least a part of said unconverted liquid fraction from step d), optionally purged, operating in the presence of at least one part and preferably all of the gaseous effluent comprising at least hydrogen from step c) of compression and a hydrocracking catalyst, at a 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 that the volume ratio liter of hydrogen / liter of hydrocarbon is between 100 and 2000 L / L .

Preferably, the hydrocracking step e) 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, and so very preferred between 9 and 20 MPa, at a space speed between 0.2 and 3 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 2000 L / L.

These operating conditions used in step e) of the process according to the invention generally make it possible to achieve conversions by pass, into products having boiling points below 340 ° C, preferably below 370Ό and preferably below at 380 ° C., greater than 15% by weight and even more preferably between 20 and 80% by weight.

Nevertheless, the conversion per pass in step e) is kept low in order to maximize the selectivity of the process in product having boiling points between 150 and 370 ° C (middle distillate). Pass conversion is limited by the use of a high recycle rate on the hydrocracking second stage loop. This rate is defined as the ratio between the feed rate of step e) and the rate of charge of step a), preferably this ratio is between 0.2 and 4.10, preferably between 0 , 5 and 2.

According to the invention, the hydrocracking step e) operates in the presence of at least one hydrocracking catalyst. Preferably, the second stage hydrocracking catalyst is chosen from the conventional hydrocracking catalysts known to those skilled in the art. The hydrocracking catalyst used in said step e) may be the same or different from that used in step a) and preferably different.

The hydrocracking catalysts used in hydrocracking processes are all of the bifunctional type combining an acid function with a hydrogenating function. The acid function is provided by large surface supports (150 to 800 mig-1 generally) having a surface acidity, such as halogenated aluminas (chlorinated or fluorinated in particular), the combinations of boron and aluminum oxides, amorphous silica-aluminas and zeolites. The hydrogenating function is provided either by one or more metals from group VIII of the periodic table, or by a combination of at least one metal from group ViB of the periodic table and at least one metal from group VIII.

Preferably, the hydrocracking catalyst (s) used in step e) comprise a hydrogenating function comprising at least one metal from group VIII chosen from iron, cobalt, nickel, ruthenium, rhodium, palladium and platinum and preferably cobalt and nickel and / or at least one metal from group VIB chosen from chromium, molybdenum and tungsten, alone or as a mixture and preferably from molybdenum and tungsten.

Preferably, the content of group VIII metal in the hydrocracking catalyst (s) is advantageously between 0.5 and 15% by weight and preferably between 2 and 10% by weight, the percentages being expressed as percentage by weight of oxides .

Preferably, the content of group VIB metal in the hydrocracking catalyst (s) is advantageously between 5 and 25% by weight and preferably between 15 and 22% by weight, the percentages being expressed as percentage by weight of oxides.

The catalyst (s) used in step e) 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 (chlorine , fluorine preferred), and optionally at least one element from group VIIB (manganese preferred), optionally at least one element from group VB (niobium preferred).

Preferably, the hydrocracking catalyst (s) used in stage e) comprise an acid function chosen from alumina, silica alumina and zeoiiths, preferably chosen from zeoiiths Y and preferably chosen from silica alumina and the zeoiiths.

A preferred catalyst used in step e) preferably comprises at least one group VI metal and / or at least one non-noble group VIII metal, a Y zeolite and alumina.

An even more preferred catalyst comprises and preferably consists of nickel, molybdenum, a Y zeolite and alumina.

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

Step b

According to the invention, the method comprises a step f) of hydrotreating the effluent from step e) in admixture with a liquid hydrocarbon feed comprising at least 95% by weight of boiling compounds at a boiling temperature included between 150 and 400 ° C, preferably between 150 and 380 ° C and preferably between 200 and 380 ° C.

All of the effluent from step e) is therefore co-treated in a hydrotreatment step f) in mixture with a liquid hydrocarbon feed separate from said effluent from the second hydrocracking step e).

Said hydrocarbon-based liquid charge can advantageously be a charge originating from a unit external to said process according to the invention or an internal flow to said process according to the invention, said internal flow being different from said effluent from the second hydrocracking step e). Preferably, said liquid hydrocarbon feedstock is a feedstock coming from a unit external to said process according to the invention.

Preferably, said liquid hydrocarbon feedstock treated in step f) in admixture with the effluent from step e) is advantageously chosen from hydrocarbon liquid feedstocks resulting from direct distillation of a crude oil (or straight run according to Anglo-Saxon terminology) and preferably chosen from ie straight run gasoil, ie Light Vacuum Gasoil Oil (LVGO) according to Anglo-Saxon terminology or light vacuum distillate, and liquid hydrocarbon charges from a coking unit (coking according to Anglo-Saxon terminology), preferably coker gas oil according to Anglo-Saxon terminology or from a coking unit, a visbreaking unit (visbreaking according to Anglo-Saxon terminology), a unit of steam cracking (steam cracking according to English terminology) and / or a catalytic cracking unit (Fluid Catalytic Cracking according to English terminology), preferably the s LCO (light cycle oil) or light gas oils from a catalytic cracking unit, and a gas oil charge from the conversion of biomass (esterification for example), said charges can be taken alone or as a mixture.

Said liquid hydrocarbon feed can also advantageously be a liquid hydrocarbon feed from a boiling bed conversion unit of the H-Oil type.

The proportion of said distinct hydrocarbon liquid charge co-treated with the effluent from step e) in step f) represents between 20% and 80% by weight of the total mass of the total liquid mixture at the inlet of l 'step f) of hydrotreatment, preferably between 30% and 70% by weight and even more preferably between 40% and 60% by weight.

The treatment of the effluent from step e) in admixture with said hydrocarbon liquid feed in a hydrotreatment step f), downstream from the hydrocracking step e), makes it possible in addition to desulfurize said hydrocarbon liquid feed. , minimize the formation of heavy polyaromatic products (HPNA). Minimizing the formation of HPNAs makes it possible to minimize the purge required on the liquid fraction, unconverted residue (UCO) resulting from step d) and therefore to increase the overall conversion of the process. The purge rate, corresponding to the ratio between the mass flow rate of the purge flow and the mass flow rate of the hydrocarbon feedstock entering the process according to the invention is advantageously between 0 and 2%.

According to the invention, said step f) operates in the presence of hydrogen and at least one hydrotreating catalyst, at a temperature between 200 and 390 ° C, under a pressure between 2 and 16 MPa, at a space speed between 0.2 and 5 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 L / L.

Conventional hydrotreatment catalysts can advantageously be used in said step f), preferably which contain at least one amorphous support and at least one hydrodehydrogenating element chosen from at least one element from the non-noble groups VIB and VIII, and preferably at least a group VIB element and at least one non-noble group VIII element.

Preferably, the amorphous support is alumina or silica alumina.

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

Surprisingly, the hydrotreatment step f) also allows the conversion of the unconverted part of the effluent from the hydrocracking step e), which makes it possible to reduce the amount of catalyst used in the step e) hydrocracking with iso conversion by pass of the step constituted by the combination of step e) of hydrocracking and of step f) of hydrotreatment. Furthermore, the presence of the hydrotreatment stage f) increases the amount of hydrogen in the recycle of the unconverted liquid fraction having a boiling point above 340 ° C (UCO) towards stage e) d hydrocracking, which facilitates their conversion in said step e) and thus further decreases the amount of catalyst required in said step (with iso-lifespan).

The hydrocracking step e) and the hydrotreating step f) can advantageously be carried out in the same reactor or in different reactors. In the case where they are carried out in the same reactor, an intermediate injection of the hydrocarbon liquid charge is advantageously implemented between the different catalytic beds. In this case, the reactor comprises several catalytic beds, the first catalytic beds comprising the hydrocracking catalyst (s) and the following catalytic beds comprising the hydrotreating catalyst (s).

Step g)

According to the invention, the method comprises a step g) of gas / liquid separation of the effluent from step f) to produce a liquid effluent and a gaseous effluent comprising at least hydrogen.

Preferably, all of the effluent from step f) of hydrotreatment is sent to step g) of separation.

Preferably, step g) of gas / liquid separation is implemented in a high pressure high temperature separator operating at a temperature between 50 and 450 ° C, preferably between 100 and 400 ° C, even more preferably between 200 and 300 ° C, and a pressure corresponding to the outlet pressure of f) minus the pressure drops.

The hydrogen-rich gaseous effluent from step g) is directed according to the invention to the first step a) of hydrocracking in order to provide the hydrogen cover necessary for this step. Stage g) of separation as well as reaction stages e) and f) located upstream operate at a pressure slightly higher than the pressure of stage a). This configuration allows direct recycle of said gaseous effluent to step a) without intermediate compression.

Thus, the recycle gas first passes from step c) of compression to the second step e) of hydrocracking, then the excess of hydrogen-rich gas from step f) is collected in i ' step g) of separation before being recycled to the first step a) of hydrocracking. The excess hydrogen-rich gas from step a) is then collected in separation step b) to finally close the hydrogen loop via compression step c). This so-called reverse hydrogen circulation mode allows the use of a single hydrogen blanket used in series by the two stages of the integrated process (reaction stages e) and f) initially, stage a) in a second time).

This configuration implies a significant reduction in the flow rate of recycle gas from the complex compared to the two-stage hydrocracking configuration according to the prior art; it also implies a higher partial pressure hydrogen operation in the second stage compared to the first stage.

Finally, in addition to limiting the flow rate of the recycle compressor, the invention makes it possible, with a single recycle compressor, to treat two separate petroleum fractions: the distillate charge under vacuum within the hydrocracking stages a) and e) hydrocracking and ia diesel fuel charge in step f) of hydrotreatment.

Description of the figure

FIG. 1 illustrates a particular embodiment of the invention.

The DSV or VGO type hydrocarbon feedstock (1) is mixed with a hydrogen-rich stream (18) coming from a gas / liquid separator flask G of step g). The mixture flow (2) enters a hydrocracking section A of step a) corresponding to the first hydrocracking step. Said section may include one or two hydrocracking reactors R1 and / or R2 (not shown in the figure). The effluent (3) from step a) is sent to a gas / liquid separator B from step b) used to isolate a gas flow comprising hydrogen (20). The gaseous effluent (20) is sent to a recycle compressor C, it is mixed with a hydrogen make-up stream (22) and then sent to the hydrocracking reactor E of the second hydrocracking step e) via the flow (21).

The liquid effluent (4) from the separator B of step b) is mixed with the liquid effluent (19) from the separator G of step g); the mixture (5) of the liquid effluents feeds a fractionation column D of step d).

An effluent comprising light cuts (6), a gasoline cut (7), a kerosene cut (8) and a diesel cut (9) are separated in the fractionation column. An unconverted liquid fraction cutter called UCO (UnConverted-Oil) (10) is also separated and then sent via the stream (12) to a second hydrocracking section E of step e). The UCO charge (12) is mixed with a stream of hydrogen (21) from the compressor C before sending the mixture (13) in step e). Said hydrocracking section E comprises a hydrocracking reactor R3 (not shown in the figure). A purge (11) is carried out on the flow of the non-converted liquid fraction from step d).

A liquid hydrocarbon feedstock (15) of the diesel type external to the process according to the invention is injected downstream of the hydrocracking section E of the UCO and is treated in a hydrodesulfurization section F of step f) as a mixture with the effluent from the hydrocracking section E, ie the hydrocracked UCO (14),

The effluent (17) from step f) is sent to a gas / liquid separator G from step g) used to isolate a gas flow comprising hydrogen (18).

The gaseous effluent (18) constitutes the hydrogen cover of the first step a) and is mixed with the DSV feed (1). The liquid effluent (19) from the separator G is mixed with the liquid effluent (4) from the separator B and then feeds the fractionation D.

The examples illustrate the invention without limiting its scope.

Examples:

Example 1: comparison: dedicated processes

This example is a comparative base case in which the hydrocracking processes of DSV or VGO and hydrodesulfurization of gas oils (GO) are implemented in two separate dedicated processes.

The hydrocracking unit processes a vacuum diesel fuel charge (VGO) and the diesel HDS unit processes a diesel fuel charge (GO). The characteristics of the charges are described in table 1:

Type VGO GO Debit t / h 49 51 Density t / m ³ 0.92 0.83 PI TBP ° C 300 47 PF TBP ° C 552 416 S wt% 2.18 0.68 NOT wtppm 1800 210

Table 1

Main operating conditions

Diesel hydrotreatment

The GO charge is injected into a hydrotreatment reactor under the conditions set out in Table 2:

Reactor H DS GO Temperature ° C 336 Total pressure (reactor inlet) MPa 4.8 Partial pressure H ₂ (reactor outlet) MPa 3.0 H ₂ / HC reactor inlet (excluding make-up and quench) Nm ³ / Sm ³ 150 CoMo on alumina Catalyst HR1246 WH h-1 1.05

Table 2

The catalyst used is a CoMo catalyst on alumina of the HR1246 type sold by the company Axens.

The diesel HDS process is then composed of a heat recovery train then of high pressure separation including a recycle compressor and allowing to separate on the one hand the hydrogen, the sulfur and nitrogen compounds and on the other share the desulphurized effluent feeding a steam stripper in order to separate the hydrogen sulfide and the naphtha.

The final diesel effluent has the following properties set out in Table 3:

Type GO Debit t / h 46 Density t / m3 0.82 PI TBP ° C 151 PF TBP ° C 450 S wtppm 10.00 NOT wtppm 2

Table 3

The characteristics of the recycle compressor dedicated to the diesel HDS unit are as follows:

Recycle compressor HDS GO Debit under operating conditions m3 / h 810 DP MPa 2.0 Power kW 520

Table 4

Two stage hydrocracker

The VGO charge is injected in a first hydrocracking step consisting of two reactors

R1 and R2. The first reactor R1 contains hydrotreatment catalyst operated under the conditions set out in Table 5:

Reactor R1 Temperature VS 385 Total pressure (reactor inlet) MPa 16.2 H2 / HC (excluding make-up and quench) Nm ³ / Sm ³ 600 CoMo on alumina Catalyst HR1058 WH h-1 1.55

Table 5

The catalyst used is a NiMo catalyst on alumina of the HR1058 type sold by the company Axens.

The effluent from this reactor is then mixed with a stream of hydrogen to be cooled and is then injected into a second reactor known as hydrocracking R2 operating under the conditions of Table 6:

Reactor ; R2 Temperature ° C ί 390 Partial pressure H ₂ (reactor outlet) MPa 13.0 Metal on zeolite Catalyst HYK753 WH h-1 3.3

Table 6

The catalyst used is a metal catalyst on zeolite of the HYK753 type sold by the company Axens.

R1 and R2 constitute the first stage of the hydrocracker, the effluent of R2 is then sent in a separation stage composed of a heat recovery train then of high pressure separation including a recycle compressor and making it possible to separate d on the one hand hydrogen, hydrogen sulphide and ammonia and on the other hand the liquid effluent supplying a stripper then an atmospheric fractionation column in order to separate flows concentrated in H ₂ S, naphtha, kerosene, diesel has the desired specification, and an unconverted heavy flow. This unconverted heavy flow is injected into a hydrocracking reactor R3 constituting the second hydrocracking step. This R3 reactor is operated under the conditions set out in Table 7:

Reactor R3 Temperature ° C 370 Total pressure (reactor inlet) MPa 15.6 Partial pressure H ₂ (reactor outlet) MPa 13.4 H2 / HG ; (excluding make-up and quench) Nm ³ / Sm ³ 900 Metal on amorphous silica-alumina Catalyst HDK766 WH h-1 1.4

Table 7

The catalyst used is a metal catalyst on amorphous silica-alumina of the HDK766 type sold by the company Axens.

The R3 effluent is then injected into the high pressure separation step downstream from the first hydrocracking step. The mass flow at the inlet of the reactor R3 is equal to the mass flow of the VGO charge, a purge corresponding to 1% by mass of the flow of the VGO charge is taken at the bottom 15 of fractionation on the flow of unconverted oil.

The diesel cut produced in the hydrocracker and recovered from the fractionation column conforms to the Euro V specifications, in particular it has less than 10 ppm by weight of sulfur.

The characteristics of the recycle compressor dedicated to the VGO hydrocracking unit are as follows:

Recycle compressor HCK DSV Debit under operating conditions m ^J / h 1270 DP MPa 3.0 Power kW 1420

Table 8

Example 2: According to the invention

This example is a diagram in accordance with the invention in which hydrodesulfurization of gas oils takes place in co-processing with the second stage e) hydrocracking effluent (therefore with hydrocracked UCO) and within which the circulation of hydrogen is reversed. This scheme therefore consists of a single two-stage hydrocracker (there is no dedicated process for hydrodesulfurization of diesel).

The second hydrocracking step e) consists of the reactor R3 and treats an unconverted heavy flow originating from an atmospheric fractionation column (stage d) as a mixture with a hydrogen flow originating from the compression stage c). The mass flow at the inlet of reactor R3 is equal to the mass flow of the VGO or DVS charge, a purge corresponding to 1% by mass of the flow of the VGO charge is taken at the bottom of the fractionation on the flow of unconverted oil . The reactor R3 operates under operating conditions identical to those of Example 1, described in Table 8.

According to the invention, the effluent from reactor R3 is then mixed with a charge GO identical to that of example 1 described in table 1, and external to the process according to the invention. This GO charge was previously preheated by a means known to those skilled in the art, by thermal integration with another process flow. The effluent mixture from reactor R3 and the GO charge is then injected into a hydrotreatment reactor R4 (step f) whose target is the desulphurization of the GO charge. The operating conditions of this reactor are the following set out in Table 9:

Reactor ; R4 ί Temperature ° C | 385 Partial pressure ; h ₂ MPa 12.0 NiMo on alumina Catalyst HR 1058 WH h-1 5.0

Table 9

The catalyst used is a NiMo catalyst on alumina of the HR1058 type sold by the company Axens.

The effluent from reactor R4 (step f) is then injected into the high pressure separation step g), making it possible to isolate a gaseous effluent rich in hydrogen. This gaseous effluent is directed to the first hydrocracking step a) in order to supply the necessary hydrogen.

The first hydrocracking step a) is supplied with gaseous effluent rich in hydrogen according to the invention by the gas / liquid separator g) located downstream of the second hydrocracking step. R1 and

R2 operate on the VGO or DSV charge described in Table 1. The operating conditions of these two reactors are modified by the new mode of circulation of hydrogen and detailed in Tables 10 and 11.

Reactor R1 Temperature ° C 385 Total pressure (reactor inlet) MPa 14.0 H ₂ / HC (excluding quench) Nm7Sm " 1,000 CoMo on alumina Catalyst HR1058 WH h-1 1.20

Table 10 Reactor R2 Temperature ° C ί 390 Partial pressure H ₂ (reactor outlet) MPa 11.5 Metal on zeolite Catalyst HYK753 WH h-1 3.0

Table 11

The pressure of the first stage is reduced compared to Table 5 of the conforming example. According to the invention, this pressure corresponds to the inlet pressure of the second stage minus the pressure drops from the reactors R3, R4 and the various equipment allowing the thermal integration of the complex.

Conversely, the hydrogen coverage of the first stage is increased compared to the non-conforming example. It results from the cover imposed in second stage; this second effect partially counterbalances the absolute pressure drop.

At iso-performance, the WH is slightly decreased in order to compensate for the decrease in partial pressure of hydrogen resulting from the combined effects of pressure drop / increase in hydrogen coverage.

The R2 effluent is sent in a separation step b) composed of a heat recovery train then of high pressure separation making it possible to separate on the one hand the hydrogen, the hydrogen sulfide and the ammonia and on the other hand the liquid effluent from the first hydrocracking step.

The gaseous effluent is directed to the compression step c) of the complex and constitutes the recycle gas 20 from the unit sent first to the hydrocracking step e).

The liquid effluents from the two hydrocracking stages feed from the gas / liquid separators

b) and g) a stripper then an atmospheric fractionation column (step d). This step d) makes it possible to isolate the following streams: gas stream concentrated in H ₂ S, naphtha, kerosene, gazoie, and an unconverted heavy liquid fraction (UCO) having a boiling point above 380 ° C. and constituart ia charge of the second hydrocracking step e). The diesel cut produced recovered from the fractionation column complies with the Euro V specifications, in particular it has less than 10 ppm by weight of sulfur.

The characteristics of the recycle compressor of the integrated complex according to the invention are:

Recycle compressor HCK DSV integrated Debit under operating conditions m3 / h 635 DP MPa 5.0 Power kW 1420

Table 12

Table 12 shows in comparison with the non-conforming example a reduction by a factor of two in the gas flow circulating in the iso-power reaction loop of the recycle compressor.

Unexpectedly, the implementation of the reactor R4 of step f) under the stated operating conditions associated with a reverse hydrogen circulation makes it possible, with respect to the dedicated methods of example 1, to:

- Reduce the catalytic volume necessary for hydrotreating the diesel cut;

- Limit the number of equipment, and in particular be limited to a single recycle compressor for the entire complex;

- Reduce the design capacity of the recycle compressor of the integrated complex without degrading the hydrogen coverage of each of the reaction sections;

- Reduce the design capacity of high pressure equipment in the effluent separation section;

- Reduce the initial investment;

- Improve the overall efficiency of the process.

Claims (11)

1. Hydrocracking process of hydrocarbon feedstocks (1) containing at least 20% by volume and preferably at least 80% by volume of compounds boiling above 340 ° C., said process comprising at least the following steps: a) Hydrocracking (A) of said charges operating, in the presence of a gaseous effluent comprising at least hydrogen from separation step g) (18) and at least one hydrocracking catalyst, a temperature between 250 and 480 ° 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 L / L, b) The gas / liquid separation (B) of the effluent from step a) (3) to produce a liquid effluent (4) and a gaseous effluent comprising at least hydrogen (20), c) Sending the gaseous effluent comprising at least hydrogen in a compression step (C) before its recycling (21) in the second hydrocracking step e) (E), d) The fractionation (D) of the liquid effluent from step b) of separation (4) and of the liquid effluent from step g) of separation (19) into at least one effluent comprising the products converted hydrocarbons having boiling points below 340 ° C (7) (8) and (9) and an unconverted liquid fraction having a boiling point above 340 ° C (10), e) Hydrocracking (E) of at least part of said unconverted liquid fraction from step d) of fractionation (12) operating, in the presence of at least part of the gaseous effluent comprising at least hydrogen from step c) of compression (21) and a hydrocracking catalyst, at a 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 that the volume ratio of liter of hydrogen / liter of hydrocarbon is between 100 and 2000 L / L, f) The hydrotreatment (F) of the effluent from step e) (14) in mixture with a liquid hydrocarbon feed comprising at least 95% by weight of boiling compounds at a boiling temperature of between 150 and 40 ° C (15), said hydrotreatment step f) operating in the presence of hydrogen and at least one hydrotreatment catalyst, at a temperature between 200 and 390 ° C, under a pressure between 2 and 16 MPa, at a space velocity 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 100 and 2000 L / L, g) The gas / liquid separation of the effluent from step f) of hydrotreatment (17) to produce a liquid effluent (19) and a gaseous effluent comprising at least hydrogen (18) and sending from said gaseous effluent to the first hydrocracking step a). 2. Method according to claim 1 wherein the hydrocarbon feedstocks (1) treated in said process and sent in step a) are chosen from hydrocarbon feedstocks containing at least 80% by volume of compounds boiling between 370 and 580 ° C. 3. Method according to one of claims 1 or 2 wherein the hydrocarbon feedstocks (1) treated in said process and sent in step a) are chosen from vacuum distillates (DSV) chosen from gas oils obtained from distillation direct from the crude oil or from conversion units and the distiilates originating from desulfurization or hydroconversion of atmospheric residues and / or vacuum residues, deasphalted oils, and the charges derived from biomass or any mixture of the charges mentioned above. 4. Method according to one of claims 1 to 3 wherein the hydrocracking step a) operates at a temperature between 320 and 450 ° C, under a pressure between 3 and 20 MPa, at a 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 L / L. 5. Method according to one of claims 1 to 4 wherein said hydrocarbon feedstocks treated (1) in said process are sent in a hydrotreatment step before being sent in said step a) of hydrocracking (A), said hydrotreatment stage operating in the presence of hydrogen and a hydrotreatment catalyst and at a temperature between 200 and 400 ^!> C, under a pressure between 2 and 16 MPa, at a space velocity between 0.2 and 5 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 L / L. 6. Method according to one of claims 1 to 5 wherein the method comprises a step d) of fractionating the liquid effluent from step b) into at least one effluent comprising the converted hydrocarbon products having points of boiling below 380 ° C (7) (8) and (9) and an unconverted liquid fraction having a boiling point above 38 ° C (10). 7. Method according to one of claims 1 to 6 wherein a purge is carried out on the unconverted liquid fraction having a boiling point above 340 ° C. 8. Method according to one of claims 1 to 7 wherein the hydrocracking step e) (E) operates at a temperature between 320 and 450 ° C, under a pressure between 3 and 20 MPa, at a 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 L / L. 9. Method according to one of claims 1 to 8 wherein the liquid hydrocarbon feed used in step f) (15) comprises at least 95% by weight of boiling compounds at a boiling temperature between 150 and 380 ° C. . 10. Method according to one of claims 1 to 9 wherein said liquid hydrocarbon feedstock 70 treated in step f) (15) mixed with the effluent from step e) (14) is chosen from diesel straight run, Light Vacuum Gasoil Oil (LVGO) according to Anglo-Saxon terminology or light vacuum distillate, and liquid hydrocarbon charges from a coking unit (coking according to Anglo-Saxon terminology), preferably diesel coker, a visbreaking unit (visbreaking according to Anglo-Saxon terminology), a 75 steam cracking unit (steam cracking according to Anglo-Saxon terminology) and / or a catalytic cracking unit (Fluid Catalytic Cracking according to Anglo-Saxon terminology), preferably LCOs (light cycle oil) or light diesel oils from a catalytic cracking unit, and a diesel charge from the conversion of biomass. 11. Method according to one of claims 1 to 10 wherein the liquid hydrocarbon feedstock 80 used in step f) (15) is external to said process.