EE05783B1 - Method and device for converting hydrocarbon feedstock comprising a shale oil by decontamination, hydroconversion in an ebullating bed, and fractionation by atmospheric distillation - Google Patents

Abstract

Method and device for converting hydrocarbon feedstock comprising a shale oil. The method comprises a decontaminating step, a hydroconversion in an ebullating bed, a fractionation to give light, naphtha, gas-oil and heavier than gas-oil fractions, the naphtha and gas-oil fractions being hydrotreated, the fraction heavier than gas-oil being sent back to the decontaminating step. The method and device aim to maximize the yield of fuel bases.

Description

Technical field

The invention belongs to the field of shale oil processing and relates to a method and a device for processing hydrocarbon feedstock containing shale oil into lighter products suitable for fuels and/or feedstock for the petrochemical industry. More specifically, the invention relates to a method and a device for processing hydrocarbon feedstock containing shale oil, which includes a decontamination step, a step of hydrocracking the decontaminated oil in a fluidized bed, followed by a fractionation step by atmospheric distillation into a gas fraction, a naphtha fraction and a diesel fraction and for separating a heavier fraction from the diesel fraction, and hydrogen treatment of the naphtha and diesel fractions. The method and the device enable shale oil to be processed into fuels of very good quality with excellent yield.

State of the art

Due to the volatility of the barrel price and the decline in the discovery of traditional oil fields, oil companies have turned their attention to alternative sources of oil. Alongside oil sands and deep-sea oil reserves, oil shale, although relatively little known, is of increasing interest.

Oil shale is a sedimentary rock that contains an insoluble organic substance called kerogen. In situ or ex situ thermal processing ("retorting" in Anglo-Saxon terminology) at temperatures between 400 and 500 °C in the absence of air releases shale oil, which is generally similar to petroleum.

Although the composition of shale oil differs from petroleum, shale oil can be used instead of petroleum, and shale oil can also be a source of chemical intermediates.

However, shale oil cannot be used directly as a substitute for petroleum. Although shale oil shares certain properties with petroleum (e.g., similar hydrogen/carbon ratio), they differ in chemical composition, particularly in the higher content of metallic and/or non-metallic compounds, which makes the processing of this alternative oil source even more difficult than petroleum. In particular, shale oil has a much higher oxygen and nitrogen content than petroleum. Shale oil may also contain higher concentrations of olefins, sulfur, and metal compounds (especially arsenic-containing compounds).

Shale oil obtained from kerogen pyrolysis contains a large amount of olefinic compounds formed during cracking, which requires additional hydrogen for processing. Thus, the bromine number, which allows the calculation of the concentration of olefinic hydrocarbons (by the addition of bromine to the ethylenic double bond), is generally higher than 30 g/100 g for a hydrocarbon feed containing shale oil, while for petroleum residues it is in the range of 1 to 5 g/100 g. Olefinic compounds obtained from cracking consist mainly of monoolefins and diolefins. Unsaturated bonds in olefins are a potential source of instability due to polymerization and/or oxidation.

The oxygen content of shale oil is generally higher than that of petroleum and can reach up to 8% by weight of the raw material. The oxygen compounds are often phenols or carboxylic acids. Therefore, shale oil can be significantly acidic.

The sulfur content varies from 0.1 to 6.5 wt%, which is why shale oil requires extensive desulfurization to meet fuel specifications. Sulfur compounds include thiophenes, sulfides, or disulfides. In addition, the sulfur content of shale oil can be different from that obtained from petroleum.

The most characteristic feature of shale oils, however, is their high nitrogen content, which makes them unsuitable as conventional refining feedstocks. Petroleum typically contains about 0.2 wt% nitrogen, while shale oil generally contains 1 to 3 wt% or more nitrogen. In addition, petroleum typically contains higher-boiling nitrogen compounds, while the boiling points of nitrogen compounds in shale oil are generally distributed over the entire boiling range of the material. The nitrogen compounds in petroleum are mainly non-basic compounds, while generally about half of the nitrogen compounds in crude shale oils are basic. The presence of such basic nitrogen compounds in refining feedstocks is highly undesirable, as these compounds often act as catalyst poisons. In addition, a common problem with many products derived from shale oil is product instability. This instability, including photosensitivity, appears to be mainly caused by nitrogen compounds. Therefore, shale oil must undergo refining processing under elevated pressure to produce synthetic crude oil or fuel that meets current specifications.

It is also known that shale oil may contain residues of many metal compounds, usually present as organometallic complexes. Among the metal compounds, mention may be made of nickel, vanadium, calcium, sodium, lead or iron and arsenic compounds. In fact, shale oil may contain arsenic in amounts exceeding 20 ppm, whereas in petroleum the arsenic amounts are generally in the order of ppb (parts per billion). All these metal compounds are catalyst poisons. In particular, they irreversibly damage hydrotreating catalysts and hydrogenation catalysts by progressively depositing on the active surface. The metal compounds and some arsenic compounds are mainly found in the fraction heavier than the diesel fraction and are eliminated by deposition on the catalyst. On the other hand, since arsenic-containing products can form volatile compounds, these compounds may be present in the lighter fractions and therefore can damage the catalysts in subsequent processing processes.

In addition, shale oil generally contains sand sediments originating from the oil shale deposits from which the shale oil is extracted. These sand sediments can cause problems with blockages, especially in fixed-bed reactors.

Finally, shale oil contains impurities that give the shale oil a pour point higher than ambient temperature, which hinders the transport of shale oil in pipes.

Due to its significant reserves and their valorization as a promising oil source, it is necessary to process shale oil into lighter fractions suitable for use as fuels and/or as feedstock for the petrochemical industry. Shale oil processing methods are known. Typically, processing involves either coking or viscosity reduction with hydrogen (hydrothermal cracking) or hydroconversion (catalytic hydrogenation). Liquid-liquid extraction methods are also known.

For example, patent document CA2605056 describes a method for processing heavy crudes with a boiling point above 340 °C, in which the crude is subjected to a deasphalting step and then the resulting raffinate is subjected to hydroconversion in the presence of a dispersed catalyst. The raffinate that is not processed during the hydroconversion is returned to the deasphalting step. The crudes discussed in this document are only atmospheric and vacuum distillation residues obtained from conventional petroleum, the processing of shale oil is not described. Only one desulfurization step is provided for the diesel fraction distilled at atmospheric pressure. One additional step is described in vacuum distillation with recovery of the vacuum residue.

Patent document CA2464796 describes a method for processing heavy feedstocks, which is quite similar to the above-mentioned document CA2605056. Document CA2464796 does not contain any reference to the processing of shale oil; the feedstocks described are limited to residues from atmospheric and vacuum distillation. Furthermore, the vacuum distillation step is optional. It also does not describe the recycling of the residue.

Patent application US2007138058 describes a slurry hydroconversion process in which the feedstock undergoes a preliminary hydrotreatment or deasphalting step. The processed products are subjected to an unspecified final hydrogen treatment. The described process is used for various heavy crudes derived from petroleum. Shale oil is not mentioned.

Patent application US2004163996 relates to a method for processing atmospheric distillation residue or vacuum distillation residue, in which said residue is subjected to a deasphalting step and then hydroconversion is carried out separately with the deasphalted oil (raffinate) and asphalt (extract) fractions using a fluidized bed method. The application does not refer to the processing of shale oil or to treatments suitable for each fraction obtained from shale oil.

Patent application US 2009166253 provides for the combination of several deasphalting steps, followed by one or more hydrocracking steps of the deasphalted oil, followed by fractionation. The method is used for various feedstocks, including shale oil, but it is a complex process in which not every fraction contained in the shale oil is appropriately treated.

The essence of the invention

The presence of a certain amount of metallic and/or non-metallic impurities inherent in shale oil makes the processing of this alternative oil source much more difficult compared to petroleum. Thus, the aim of industrially used shale oil processing methods is to develop methods adapted to hydrocarbon feedstock containing shale oil in order to obtain maximum yields of good quality fuels. The processing methods known for petroleum can therefore be adapted to the specific composition of shale oil.

The aim of the present invention is to improve the efficiency of known processing methods for hydrocarbon raw materials containing shale oil, more specifically to increase the yield of fuels by means of a combination of specifically interconnected stages and a treatment adapted to each fraction obtained from shale oil. The aim of the present invention is also to obtain good quality fuels and products, which would have, in particular, a low content of sulfur, nitrogen and arsenic in accordance with the specifications. Another aim is to propose a simple, i.e. with the fewest necessary stages, but at the same time effective method, which allows to limit investment costs.

In its broadest form and according to a first aspect, the present invention is defined as a method for processing a hydrocarbon feedstock containing at least one shale oil having a nitrogen content of 0.1 - 3.0 wt%, characterized in that it comprises the following steps:

a) decontamination is carried out on hydrocarbon raw materials containing shale oil, resulting in a residual fraction and decontaminated oil,

b) the decontaminated oil is directed to a hydroconversion zone in the presence of hydrogen, said zone comprising at least one fluidized bed reactor operating in a rising gas-liquid flow and comprising at least one supported hydroconversion catalyst,

c) in step b), the obtained liquid product is partially or completely directed to a fractionation zone, where the gas fraction, oil fraction, diesel fraction and fraction heavier than the diesel fraction are collected by atmospheric distillation,

d) said petroleum fraction is partially or completely treated in the presence of hydrogen in a first hydrotreating zone, said first zone comprising at least one first fixed bed reactor containing at least one hydrotreating catalyst, and

e) said diesel fraction is partially or completely treated in a second hydrotreating zone in the presence of hydrogen, said second zone comprising at least one second fixed bed reactor comprising at least one second hydrotreating catalyst.

Typically, the hydrogen conversion zone of step b) comprises one to three, preferably two, consecutive reactors, and the first and second hydrotreatment zones of steps c) and d) typically comprise one to three consecutive reactors, independently of each other.

Preferably, the method comprises an additional step f), in which the fraction heavier than diesel is returned to step a) for decontamination.

The study of shale oil processing carried out by the patent applicants has shown that it is possible to improve the efficiency of existing methods in terms of fuel yield and product purity by combining different stages that are interconnected in a specific way. Each fraction obtained by the method according to the invention is then directed to a processing zone.

In the first phase, the hydrocarbon feedstock containing shale oil is subjected to decontamination, preferably by deasphalting using a solvent that is exclusively C3-C5 hydrocarbons or a mixture thereof. The solvent is chosen to separate the asphalt, which contains heavy aromatic compounds insoluble in the solvent. The extraction step also allows to reduce the proportion of heat-resistant aromatic nitrogen compounds that are stable to hydrogen deazotization (deazotization by catalytic hydrogenation), to remove solid particles and minerals originating from the oil shale and to get rid of a large part of heavy organometallic compounds containing metals such as vanadium or nickel. These heavy organometallic compounds may contain porphyrin chains responsible for binding metals. Deasphalting is carried out on the entire hydrocarbon feedstock containing shale oil in order to extract as much of the aromatic nitrogen compounds as possible, which are present in fractions ranging from LPG to a fraction heavier than diesel. Deasphalting of all hydrocarbon feedstocks containing shale oil prior to hydroconversion allows the removal of a large portion of the metallic catalyst poisons present in the feedstock, specifically arsenic, as well as heavy nitrogen compounds, which are generally aromatic. Thus, the degree of regeneration of the hydroconversion catalyst is reduced and the need for hydrogen is limited due to the lower presence of the compounds to be treated in the deasphalted oil. Examples of aromatic nitrogen compounds that may be present in feedstocks suitable for treatment by the method of the invention include pyridines, pyrimidines, pyrazines, quinolines, isoquinolines, pyrroles, imidazoles and other mono- or polycyclic aromatic heterocyclic nitrogen compounds. These aromatic nitrogen compounds may be substituted with various hydrocarbon chains that may contain heteroatoms such as nitrogen, oxygen and sulfur.

The second stage involves hydrogen conversion in a fluidized bed. Unlike the fixed bed technology, the fluidized bed technology allows the processing of hydrocarbon feedstock containing shale oil heavily contaminated with metals, heteroatoms and sediments, while providing conversion levels of over 50%. In essence, this second stage processes the shale oil into a liquid product, from which fuels can then be obtained. A large part of the metal compounds, sediments and also heterocyclic compounds are removed. The liquid product separated from the fluidized bed therefore contains the most stable nitrogen and sulfur compounds and may contain volatile arsenic compounds.

The liquid product obtained in the hydrogen conversion step is then fractionated by atmospheric distillation, resulting in different fractions, which are then subjected to specific processing of each fraction. Atmospheric distillation allows the production of different desired fractions (oil, diesel) in one step, which facilitates subsequent hydrogen treatment adapted to each fraction, and which directly produces fuels meeting different specifications. After hydrogen treatment, fractionation is therefore not necessary.

Due to the significant reduction of undesirable impurities in the fluidized bed, the lighter fractions (oil and diesel) contain fewer undesirable impurities and can therefore be processed in a fixed bed zone, where hydrogenation rates are generally higher compared to the fluidized bed. The processing conditions can also be milder due to the lower content of undesirable impurities. The fact that a treatment is provided for each fraction allows the best processing according to the desired products. Depending on the selected processing conditions, either a fraction that can be sent to fuel tanks or a product that meets the applicable specifications (sulfur content, smoke point, cetane number, aromatics content, etc.) can be obtained.

The fixed bed hydrotreating zones preferably contain trap beds upstream of the hydrotreating catalytic beds that are specific for arsenic and silicon compounds that may be present in the petroleum and/or diesel fraction. Arsenic compounds that could not be separated in the fluidized bed (as they are usually relatively volatile) are bound in the trap beds, which prevents damage to downstream catalysts and allows fuels with significantly reduced arsenic content to be obtained.

Atmospheric distillation also allows the concentration of the most stable nitrogen compounds in the heavier fraction of the diesel fraction, which is directed in step f) to step a) for decontamination, for example deasphalting. This recovery step therefore allows the reduction of the proportion of the heavier fraction of the diesel fraction and thus reduces the problems associated with the valorization and economic viability of this fraction. The heavier fraction of the diesel fraction can be directed to step a) at least in part, preferably in its entirety.

Asphalt is used in the production of heavy fuel oils and bitumen.

Detailed description

Hydrocarbon feedstock containing shale oil

A hydrocarbon feedstock containing shale oil comprises at least one shale oil or a mixture of shale oils. The term "shale oil" is used herein in its broadest sense and includes all shale oils or fractions of shale oils that contain nitrogen impurities. These include shale oil that may be obtained by pyrolysis, solvent extraction or other means, or shale oil that has been filtered to remove solids or has been treated with one or more solvents, chemical products or other means and that contains nitrogen impurities. The term "shale oil" also includes fractions of shale oil that have been obtained by distillation or other fractionation methods.

The shale oils used in the present invention generally have a Conradson coke number of at least 0.1 wt% and generally at least 5 wt%, an asphaltene content (according to IP143/C7) of at least 1 wt%, often at least 2 wt%. The sulfur content is generally at least 0.1 wt%, often at least 1 wt% and very often at least 2 wt% and even up to 4 wt% or even 7 wt%. The metal content is generally at least 5 ppm by weight, often at least 50 ppm by weight and typically at least 100 ppm by weight or at least 200 ppm by weight. The nitrogen content is generally at least 0.5 wt%, often at least 1 wt% and very often at least 2 wt%. The arsenic content is generally greater than 1 ppm by weight and up to 50 ppm by weight.

The method according to the invention is intended for processing shale oil. However, the hydrocarbon feedstock containing shale oil may also include other liquid synthetic hydrocarbons in addition to shale oil, especially those containing significant amounts of organic cyclic nitrogen compounds. These include oils obtained from coal, oils obtained from heavy tars, oil sands, oils obtained from the pyrolysis of lignin-containing residues such as wood residues, crude oils obtained from biomass ("biocrudes"), vegetable oils and animal fats.

The hydrocarbon feedstock containing shale oil may also be supplemented with other hydrocarbon feedstocks. These feedstocks are selected from the group consisting of vacuum distillates and straight-run distillation residues, vacuum distillates and crude residues obtained by processing methods such as distillation to coke (coking), products obtained from fixed-bed hydrocracking of heavy fractions, products obtained from fluidized-bed hydrocracking of heavy fractions, and solvent-deasphalted oils (e.g., oils deasphalted with propane, butane, and pentane, derived from the deasphalting of straight-run vacuum residues or vacuum residues obtained from hydrocracking). The hydrocarbon feedstocks may also include light cycle oil (LCO) from various sources, heavy cycle oil (HCO) from various sources, and also diesel fractions obtained from catalytic cracking, which typically have a distillation range of about 150 °C to about 650 °C. The hydrocarbon feedstocks may also include aromatic extracts obtained from the production of lubricating oils. The feedstocks may be prepared and used as mixtures in any ratio.

The hydrocarbons added to the shale oil or shale oil mixture may constitute 20 to 60% by weight of the total hydrocarbon feedstock (shale oil or shale oil mixture and added hydrocarbons) or even 10% by weight to 90% by weight.

Decontamination

The hydrocarbon feedstock containing shale oil is fed to a decontamination step [step a)]. The purpose of this step is to extract unwanted compounds. These unwanted compounds are compounds rich in heteroatoms such as nitrogen, oxygen and sulfur, as well as most of the metal-rich compounds.

One preferred decontamination method is deasphalting.

Decontamination can be carried out by solvent extraction or ultrafiltration on a membrane, for example Zr carbon, for example in the presence of supercritical CO2 (C. Rodriguez et al. Desalination 144(2002), 173-178).

Solvent deasphalting is carried out under conditions well known to those skilled in the art. For example, methods such as Solvahl from Axens or Rose from KBR can be used.

Deasphalting is usually carried out with an aliphatic solvent, generally C3-C7, preferably C3-C5, alkane or cycloalkane, or mixtures thereof in any ratio.

The decontamination of step a) is carried out with a solvent selected from the group consisting of propane, n-butane, isobutane, n-pentane, cyclopentane, 2-methylbutane, 2,2-dimethylpropane and mixtures thereof in any ratio.

Deasphalting can be carried out by any method known to those skilled in the art. Extraction is generally carried out in a mixer-decanter or an extraction column. Preferably, extraction is carried out in an extraction column.

The processing conditions are generally a solvent/feed ratio of 3/1 to 8/1 vol%/vol%, preferably 4/1 to 6/1 vol%/vol%, and a temperature between 60 and 250°C, preferably between 60°C and 200°C. The processing pressure must be maintained above the critical pressure of the solvent used. It is preferably between 4 and 5 MPa.

In a preferred embodiment, a mixture comprising a hydrocarbon feed containing shale oil and a first portion of a solvent amount is introduced into the extraction column, wherein the volume ratio of the solvent amount to the hydrocarbon feed is referred to as the solvent content introduced with the hydrocarbon feed. The purpose of this step is to mix the feed thoroughly with the solvent entering the extraction column. A second portion of the solvent amount may be introduced into the bottom of the extractor in the settling zone, wherein the volume ratio of the second solvent amount to the hydrocarbon feed is referred to as the solvent content introduced from the bottom of the extractor. The volume of the hydrocarbon feed in the settling zone is generally the same as that introduced into the extraction column. The sum of the two volumes of each solvent amount to the hydrocarbon feed is referred to as the overall solvent content. Asphalt settling involves countercurrent washing of an asphalt emulsion in a solvent-oil mixture with a pure solvent. This is facilitated by increasing the solvent content (in effect, the treatment involves replacing the solvent-oil medium with a pure solvent medium) and reducing the temperature.

The solvent can be recovered either by solvent evaporation (multi-stage evaporators with pressure reduction and temperature increase), generally followed by vapor separation, or by treating the solvent or solvent-deasphalted oil mixture at a pressure above the critical pressure to separate the solvent, which reduces the energy consumption of evaporation.

The extraction yields a yield with a nitrogen content reduced to approximately half that of the hydrocarbon feedstock containing shale oil. At least a portion, and preferably all, of the deasphalted oil is fed to a fluidized bed reactor for hydrogen conversion in the presence of hydrogen. The fluidized bed contains a supported hydrogen conversion catalyst.

According to a preferred embodiment, the asphalt is fed to a gasification zone with oxygen and steam, where it is converted into a gas containing hydrogen and carbon monoxide. This gas mixture can be used for the synthesis of methanol or for the synthesis of hydrocarbons using the Fischer-Tropsch reaction. According to the present invention, this mixture is preferably fed to a steam conversion zone (shift conversion), where it is converted into hydrogen and carbon dioxide in the presence of steam. The hydrogen obtained can be used in steps b), d) and e) of the method according to the invention. The asphalt obtained in step e) can also be used as a solid fuel or, after liquefaction, as a liquid fuel or added to the composition of bitumens (after an optional purge step) and/or heavy fuel oils.

Deasphalting of shale oil-containing hydrocarbon feedstock thus allows the extraction of stable aromatic compounds containing nitrogen and unwanted impurities (metals), as well as solid particles and sediments, which sometimes constitute 0.2% by weight of shale oil-containing hydrocarbon feedstock. Carrying out a previous deasphalting step on the feedstock allows the saving of the hydroconversion catalyst used in the next step and the minimization of the continuous addition of catalyst.

Hydrogen conversion

After decontamination by deasphalting, the resulting raffinate (deasphalted oil or DAO or hydrocarbon feedstock containing decontaminated shale oil) is subjected to a fluidized bed hydroconversion step [step b)]. Hydroconversion refers to the reactions of hydrogenation, hydrotreating, hydrodesulfurization, hydrodeazotization, hydrometallization and hydrocracking.

The use of a fluidized bed catalytic reactor, which involves the upward recirculation of the reactor fluids through a stirred catalyst bed, is generally well known. Fluidized bed technologies generally employ catalysts on extruded supports, which typically have a diameter of the order of 1 mm or less, for example greater than or equal to 0.7 mm. The catalysts remain in the reactors and are not removed with the products. The catalytic activity can be kept constant by continuously replacing (adding and removing) the catalyst. Thus, it is not necessary to stop the plant to change the catalyst in use or to increase the reaction temperatures to compensate for deactivation during the cycle. In addition, operation under constant conditions allows for a uniform quality and constant yield of product throughout the catalyst cycle. Since the catalyst is continuously stirred in a strong fluid circulation, the pressure drop in the reactor remains low and constant, and the heat of reaction is rapidly equalized in the catalytic bed, which is therefore almost isothermal and does not require cooling by the addition of quenchers. Carrying out the hydroconversion in a fluidized bed avoids the problems of catalyst fouling caused by natural compounds in shale oil.

In step b) the conditions for treating the feedstock in the presence of hydrogen are those known for the hydroconversion of a liquid hydrocarbon fraction in a fluidized bed. The treatment is usually carried out at a pressure of 2 to 35 MPa, preferably 10 to 20 MPa, at a temperature of 300 °C to 550 °C and often 400 °C to 450 °C. The weight hourly space velocity (WHSV) and the hydrogen partial pressure are important factors which are selected depending on the properties of the product to be treated and the desired treatment. Most often the WHSV is in the range of 0.2 h-1 to 1.5 h-1 and preferably 0.4 h-1 to 1 h-1. The amount of hydrogen mixed with the shale oil-containing hydrocarbon feedstock is typically 50 to 5000 normal cubic meters (Nm3) per cubic meter (m3) of liquid feedstock, typically 100 to 1000 Nm3/m3, and preferably 300 to 500 Nm3/m3.

This hydroconversion step b) can typically be carried out under the conditions of the T-STAR® process, as described, for example, in the publication Heavy Oil Hydroprocessing, published by l'Aiche, March 19-23, 1995, HOUSTON, Texas, document number 42d. It can also be carried out under the conditions of the H-OIL® process, as described, for example, in the publication The H-Oil®Process, A Worldwide Leader In Vacuum Residue Hydroprocessing, by JJ. Colyar and L.I. Wisdom, at the NPRA Annual Meeting, March 16-18, 1997.

The hydrogen required for hydroconversion (and other subsequent hydrogen treatments) can be obtained from steam conversion of hydrocarbons (methane) or from gas obtained from oil shale.

The catalyst of step b) is preferably a granular hydrogenation catalyst consisting of at least one metal or metal compound having hydrogenation-dehydrogenation activity supported on an amorphous support. Generally, a catalyst with a porosity suitable for the treatment of hydrocarbon feedstocks containing metals is used.

The hydrogenation-dehydrogenation effect can be obtained by at least one Group VIII metal selected from nickel and cobalt, optionally in combination with at least one Group VIB metal selected from molybdenum and tungsten. For example, a catalyst can be used comprising 0.5 to 10 wt% nickel and preferably 1 to 5 wt% nickel (expressed as nickel oxide NiO), and 1 to 30 wt% molybdenum, preferably 5 to 20 wt% molybdenum (expressed as molybdenum oxide MoO3), on an amorphous inorganic support. The total content of Group VIB and Group VIII metal oxides is often 5 to 40 wt% and generally 7 to 30 wt%. The weight ratio of Group VIB metal (or metals) to Group VIII metal (or metals), expressed as metal oxide, is generally 20 to 1 and most often 10 to 2.

The catalyst support is selected, for example, from alumina, silica, aluminosilicates, magnesia, clays and mixtures of at least two of these minerals. This support may also contain other compounds, for example oxides selected from boric oxide, zirconium oxide, titania and phosphorous anhydride. Typically, an alumina support is used and very often an alumina support supplemented with phosphorus and optionally boron. In this case, the concentration of phosphorous anhydride P2O5 is typically below about 20% by weight and most often below about 10% by weight and at least 0.001% by weight. The concentration of boron trioxide B2O3 is typically from 0 to about 10% by weight. The alumina used is typically γ (gamma) or n (eta) alumina. The catalyst is typically in extruded form. Preferably, the catalyst of step b) is based on nickel and molybdenum supplemented with phosphorus and is on an alumina support. For example, the HTS 458 type catalyst sold by AXENS can be used.

Before introducing the deasphalted oil, sulfurization can be carried out with the catalysts used in the process according to the present invention, by which it is possible to convert the metal species at least partially into sulfides before they are brought into contact with the raw material to be processed. This activating sulfurization is well known to those skilled in the art and can be carried out using any of the methods described in the literature, either in situ, i.e. in a reactor, or ex situ.

The spent catalyst is partially replaced by fresh catalyst by removing it through an opening in the bottom of the reactor and introducing fresh or new catalyst from the top of the reactor at regular intervals, for example in a single injection or in a semi-continuous manner. For example, fresh catalyst can be added every day. The rate of replacement of the spent catalyst with fresh catalyst can be, for example, from about 0.05 kg to about 10 kg per m3 of feedstock. This removal and replacement is carried out by means of equipment that allows this hydrogenation step to be carried out continuously. The equipment usually includes a circulation pump that allows the catalyst to be kept in continuous circulation in the fluidized bed by removing at least a portion of the liquid from the upper part of the reactor and re-introducing it from the lower part of the reactor. It is also possible to direct the spent catalyst removed from the reactor to a regeneration zone, where the carbon and sulfur deposited on it are removed, after which the regenerated catalyst is returned to the hydrogenation reactor of step b).

The processing conditions, combined with the catalytic activity, allow for a degree of processing of the shale oil-containing hydrocarbon feedstock, which may range from 50 to 95%, preferably from 70 to 95%. The aforementioned degree of processing is defined as the mass fraction of the shale oil-containing hydrocarbon feedstock entering the reaction zone minus the mass fraction of the fraction heavier than the diesel fraction, which has a boiling point above 343 °C when leaving the reaction zone, divided by the mass fraction of the feedstock fraction entering the reaction zone.

Fluidized bed technology allows the processing of hydrocarbon feedstock containing shale oil, which is heavily contaminated with metals, sediments and heteroatoms, without the feedstock loss or plugging problems associated with the use of a fixed bed. Metals such as nickel, vanadium, iron and arsenic are largely removed from hydrocarbon feedstock containing shale oil by their precipitation onto catalysts during the reaction. Residual arsenic (volatile) is removed by specific trap layers during the hydrotreating stages. Sediment contained in shale oil is also removed by catalyst replacement in the fluidized bed without disturbing the hydroconversion reactions. These stages also allow the removal of the majority of nitrogen by hydrodeazotization, leaving only the most stable nitrogen compounds.

By means of the hydrocracking of step b), it is possible to obtain a liquid product containing not more than 0.3% by weight, preferably not more than 0.2% by weight, of nitrogen.

Fractionation by atmospheric distillation

The liquid product obtained in the hydrogen conversion step b) is partially or completely directed to a fractionation zone, where the gas fraction, oil fraction, diesel fraction and fraction heavier than diesel are collected by atmospheric distillation.

Preferably, the liquid product obtained in step b) is fractionated by atmospheric distillation into a gas fraction boiling below 50°C, a petroleum fraction boiling between about 50°C and 150°C, a diesel fraction boiling between about 150°C and 370°C, and a fraction heavier than the diesel fraction boiling generally above 340°C, preferably above 370°C.

The oil and diesel fractions are then sent to separate hydrotreating zones. The fraction heavier than the diesel fraction is sent to the decontamination unit in stage a) where it is mixed with the hydrocarbon feedstock containing shale oil.

The gas fraction contains gases (H2, H2S, NH3, H20, CO2, CO, C1-C4 hydrocarbons, etc.). It can be preferably purified for hydrogen recovery and reuse in the hydrogen conversion zone of step b) or in the hydrotreatment zones of steps d) and e). The C3 and C4 hydrocarbons can be used after purification to produce liquefied petroleum gas (LPG) products. Non-condensable gases (C1-C2) are typically used as internal fuels in the heating furnaces of hydrocracking and/or hydrotreatment reactors. The C1-C4 hydrocarbons isolated from the gas fraction can optionally be used to carry out the decontamination step a). The conditions for carrying out the decontamination (pressure, temperature, solvent/feed ratio) vary according to the properties of the hydrocarbon feedstock containing shale oil and are adapted to the desired purification parameters.

Hydrotreatment of petroleum fraction and diesel fraction

The oil and diesel fractions are then separately hydrotreated in a fixed bed [steps d) and e)]. Hydrotreating refers to the reactions of hydrodesulfurization, hydrodesulfurization and hydrometallization. Depending on the chosen processing conditions, the aim is to bring the different fractions to specifications (sulfur content, smoke point, cetane number, aromatics content, etc.) or to produce synthetic oil. Treating the oil fraction in one hydrotreating zone and the diesel fraction in another hydrotreating zone allows for improved processing so that each fraction can be brought to the required specifications with maximum yield in only one step per fraction. Fractionation after hydrotreating is therefore not necessary. The difference between these two hydrotreating zones lies more in the different processing conditions than in the choice of catalyst.

Stationary bed hydrotreating zones preferably contain specific trap beds upstream of the hydrotreating catalytic beds for arsenic (arsenide-containing compounds) and silicon compounds that may be present in the petroleum and/or diesel fraction. Arsenic compounds that could not be separated in the fluidized bed (as they are usually relatively volatile) are fixed on the trap beds, which allows to avoid damage to downstream catalysts and to obtain fuels with a significantly reduced arsenic content.

The capture layers with which it is possible to remove arsenic and silicon from petroleum or diesel fractions are known to those skilled in the art. They consist, for example, of an absorbent comprising nickel deposited on a suitable support (silica, magnesium oxide or alumina), as described in patent document FR2617497, or of an absorbent comprising copper on a support, as described in patent document FR2762004. The capture layers sold by AXENS may also be mentioned: ACT 979, ACT989, ACT961, ACT981.

The processing conditions are adapted to the shale oil-containing hydrocarbon feedstock being processed in each hydroprocessing zone. The hydroprocessing conditions for the oil fraction are generally milder than those used for the diesel fraction.

In the step of hydrotreating the petroleum fraction [step d)], the treatment is usually carried out at a pressure of 4 to 15 MPa, often 10 to 13 MPa. In this step d), the temperature is usually 280°C to 380°C, often 300°C to 350°C. This temperature is usually adjusted according to the desired level of hydrodesulfurization. The weight hourly space velocity (WHSV) is usually in the range of 0.1 h-1 to 5 h-1 and preferably 0.5 h-1 to 1 h-1. The amount of hydrogen mixed with the shale oil-containing hydrocarbon feedstock is usually 100 to 5000 normal cubic meters (Nm3) per cubic meter (m3) of liquid feedstock, usually 200 to 1000 Nm3/m3 and preferably 300 to 500 Nm3/m3. Treatment in the presence of hydrogen sulfide (for sulfurization of the catalyst) and at a partial pressure of hydrogen sulfide, typically 0.002 times to 0.1 times and preferably 0.005 times to 0.05 times the pressure, is suitable.

In the step of hydrotreating the diesel fraction [step e)], treatment at a pressure of 7 to 20 MPa, often 10 to 15 MPa, is suitable. In this step e), the temperature is usually 320°C to 450°C, often 340°C to 400°C. This temperature is usually adjusted according to the desired level of hydrodesulfurization. The mass hourly space velocity is between 0.1 h-1 and 1 h-1. Typically, the mass hourly space velocity (WHSV) is between 0.2 h-1 and 1 h-1 and preferably between 0.3 h-1 and 0.8 h-1. The amount of hydrogen mixed with the shale oil-containing hydrocarbon feedstock is typically 100 to 5000 normal cubic meters (Nm3) per cubic meter (m3) of liquid feedstock, typically 200 to 1000 Nm3/m3 and preferably 300 to 500 Nm3/m3. Treatment in the presence of hydrogen sulfide and at a partial pressure of hydrogen sulfide typically 0.002 times to 0.1 times, and preferably 0.005 times to 0.05 times the pressure, is suitable.

In the hydrotreating zones, the ideal catalyst should have a strong hydrogenation capacity to perform a thorough product treatment and significantly reduce the sulfur and nitrogen content. In a preferred embodiment, the hydrotreating zones operate at a relatively low temperature, which promotes thorough hydrogenation and limits catalyst coking. The use of a single catalyst or several different catalysts in the hydrotreating zones in a continuous or sequential manner is within the scope of the invention. Typically, the hydrotreating in steps d) and e) is carried out industrially, in one or more reactors in a descending liquid flow.

The same type of catalyst is used in the two hydrotreating zones [steps d) and e)]; the catalysts may be identical or different in each zone.

At least one hydrotreating catalyst is used, which comprises at least one metal or metal compound on an amorphous support having a hydrogenating-dehydrogenating effect.

The hydrogenation-dehydrogenation effect can be obtained by at least one Group VIII metal selected from nickel and cobalt, optionally in combination with at least one Group VIB metal selected from molybdenum and tungsten. For example, a catalyst can be used comprising 0.5 to 10 wt% nickel and preferably 1 to 5 wt% nickel (expressed as nickel oxide NiO), and 1 to 30 wt% molybdenum, preferably 5 to 20 wt% molybdenum (expressed as molybdenum oxide MoO3), on an amorphous inorganic support. The total content of oxides of Group VIB and Group VIII metals is often 5 to 40 wt% and generally 7 to 30 wt%, and the weight ratio of Group VIB metal (or metals) to Group VIII metal (or metals), expressed as metal oxide, is generally 20 to 1 and most often 10 to 2.

The support is selected, for example, from alumina, silica, aluminosilicates, magnesia, clays and mixtures of at least two of these minerals. This support may also contain other compounds, for example oxides selected from boric oxide, zirconium oxide, titania and phosphorous anhydride. Typically, an alumina support is used, and very often an alumina support supplemented with phosphorus and optionally boron. In this case, the concentration of phosphorous anhydride P2O5 is typically less than about 20% by weight and most often less than about 10% by weight and at least 0.001% by weight. The concentration of boron trioxide B2O3 is typically from 0 to about 10% by weight. The alumina used is typically γ (gamma) or n (eta) alumina. This catalyst is typically in the form of pellets or extruded forms.

Before introducing the hydrocarbon feedstock containing shale oil, sulfurization is carried out with the catalysts used in the method according to the present invention, by which it is possible to convert the metal species at least partially into sulfides before they are brought into contact with the feedstock to be processed. This activating sulfurization is well known to those skilled in the art and can be carried out using any of the methods described in the literature, either in situ, i.e. in a reactor, or ex situ.

The treatment of the petroleum fraction with hydrogen in step d) yields a fraction containing not more than 0.0001 wt% nitrogen, preferably not more than 0.00005 wt% nitrogen, and not more than 0.0005 wt% sulfur, preferably not more than 0.00005 wt% sulfur.

The hydrogenation of the diesel fraction in step e) yields a fraction containing not more than 0.01 wt% nitrogen, preferably not more than 0.002 wt% nitrogen, and not more than 0.005 wt% sulfur, preferably not more than 0.001 wt% sulfur.

Catalytic cracking

Finally, according to one variant, the method according to the invention may comprise a catalytic cracking step [step g)], in which at least part and preferably all of the heavier diesel fraction obtained in step c) is directed to a catalytic cracking zone, in which said heavier diesel fraction is processed in a manner well known to those skilled in the art to obtain a second gas fraction, a second oil fraction, a second diesel fraction and a second heavier diesel fraction, called pulp (slurry). The second diesel fraction is directed, for example, partly or entirely to fuel reservoirs (tanks) and/or partly or entirely to step e) for the treatment of diesel with hydrogen. The second heavier diesel fraction is directed, for example, partly or entirely to a heavy fuel oil reservoir (tank) and/or partly or entirely to step g) for catalytic cracking. At least part of the second heavier diesel fraction obtained in step g) is directed to step a) for decontamination. Within the scope of the present invention, the expression "catalytic cracking" refers to cracking processes that include at least one catalyst regeneration step by partial combustion, and those that include at least one catalyst regeneration step by complete combustion, and/or those that include both at least one partial combustion step and at least one complete combustion step.

A brief description of catalytic cracking (the first industrial implementation of which dates back to 1936 (Houdry method) or 1942 for the use of a catalyst in a fluidized bed) can be found in Ullmans Encyclopedia of Industrial Chemistry Volume A 18, 1991, pages 61 to 64. Typically, a known catalyst is used, which comprises a matrix, optionally an additive and at least one zeolite. The amount of zeolite varies, but is usually about 3 to 60% by weight, often about 6 to 50% by weight and usually about 10 to 45% by weight. Typically, the zeolite is dispersed in the matrix. The amount of additive is usually about 0 to about 30% by weight. The amount of matrix makes up the remainder up to 100% by weight. The additive is generally selected from metal oxides of Group IIA of the Periodic Table of the Elements, such as magnesium oxide or calcium oxide, rare earth oxides and titanates of Group IIA metals. The matrix is usually silica, alumina, aluminosilicate, magnesium silicate, clay or a mixture of two or more of these compounds. The most commonly used zeolite is zeolite Y. The cracking is carried out mainly in a vertical reactor, either in upflow or downflow. The choice of catalyst and the conditions of use depend on the desired products and the shale oil-containing hydrocarbon feedstock to be processed, as described, for example, in the article by M. Marcilly on pages 990-991, published by Revue de 1'Institut Francais du Petrole., Nov.-Dec. 1975, on pages 969-1006. The processing is usually carried out at temperatures of 450°C to 600°C and the residence time in the reactor is up to 1 minute, often from about 0.1 to about 50 seconds.

The catalytic cracking step g) may be a catalytic cracking step in a fluidized bed, for example according to the process known as R2R. This step may be carried out in a manner known to those skilled in the art under suitable cracking conditions to produce products with lower molecular weight. Descriptions of the fluidized bed cracking process in this step g) and the catalysts used are described, for example, in the patent documents US-A-5286690, US-A-5324696 and EP-A-699224.

The fluidized bed catalytic cracking reactor may be operated in an upflow or downflow mode. Although not a preferred embodiment of the present invention, catalytic cracking may also be carried out in a fluidized bed reactor. Particularly preferred catalytic cracking catalysts are those comprising at least one zeolite, typically mixed with a suitable matrix such as alumina, silica, aluminosilicate.

According to a penultimate aspect, the invention relates to the preparation of a synthetic crude oil by a method according to any of the preceding aspects.

According to a final aspect, the invention relates to a device for processing hydrocarbon feedstock containing shale oil, in which a method according to any of the preceding aspects is used.

This device includes:

- decontamination zone for processed hydrocarbon raw materials containing shale oil,

- a hydrogen conversion zone in the presence of hydrogen, comprising a fluidized bed reactor operating in a rising gas and liquid flow and comprising at least one supported hydrogen conversion catalyst,

- fractionation zone in atmospheric distillation,

- a hydrotreating zone in the presence of hydrogen, comprising a fixed bed reactor containing at least one hydrotreating catalyst,

- a second hydrotreating zone in the presence of hydrogen, comprising at least one fixed bed reactor comprising at least one hydrotreating catalyst.

These elements are combined together to perform the method according to the invention.

For this, for example:

- a decontamination zone connected to a hydroconversion zone to supply the hydroconversion zone with hydrocarbon feedstock containing shale oil processed in the decontamination zone,

- the hydrogen conversion zone is connected to the fractionation zone so that the fractionation zone is supplied with liquid products obtained in the hydrogen conversion zone,

- one connection (pipe) connects the fractionation zone to one of the two hydrotreating zones, the other connection (pipe) connects the fractionation zone to the other of the two hydrotreating zones.

A catalytic cracking zone may be provided, with a second connection (pipe) connecting the fractionation zone to this catalytic cracking zone.

The device may further include one or more circulation pipes for directing different fractions to the decontamination zone or catalytic cracking zone.

Fig. 1 schematically shows the method according to the invention. Fig. 2 schematically shows a variant of the method comprising a catalytic cracking step.

According to Fig. 1, the hydrocarbon feedstock (1) containing shale oil to be processed enters the decontamination zone (3) via a pipe (2). This step (3) is deasphalting, which is carried out using a solvent (not shown), in which deasphalted oil (4) and a residue (5) are obtained. The residue (5), which is separated via a pipe (6), can be used as a fuel or to feed a gasification unit for the production of hydrogen and energy.

The deasphalted oil (4) is fed through a line (7) to a fluidized bed hydroconversion zone (8) in the presence of hydrogen (9), with hydrogen (9) being introduced through a line (10). The liquid product from the fluidized bed hydrocracking zone (8) is fed through a line (11) to an atmospheric distillation column (12), at the outlet of which a gas fraction (13), a naphtha fraction (14), a diesel fraction (15) and a fraction heavier than the diesel fraction (16) are collected. The hydrogen-containing gas fraction (13) may be purified (not shown) for hydrogen recovery and recirculation to the fluidized bed hydrocracking zone (8) through a line (10) and/or to the hydrotreating zones (17) and/or (18) through lines (23) and (24). The oil fraction (14) is directed to a stationary bed hydrotreating zone (17), from the outlet of which the oil fraction (21) freed from impurities is collected. The diesel fraction (15) is directed to a stationary bed hydrotreating zone (18), from the outlet of which the diesel fraction (22) freed from impurities is collected. The two hydrotreating zones (17) and (18) are supplied with hydrogen via pipes (23) and (24). The fraction (16) heavier than the diesel fraction is directed to the deasphalting zone (3) via pipe (25).

In Fig. 2, the liquid-liquid extraction, hydrogen conversion, separation and hydrotreating steps (and designations) are identical to Fig. 1. The heavier than diesel fraction (16) from the atmospheric distillation step may be directed to a catalytic cracking zone (26) via a line (27). The liquid product from this zone (26) is directed via a line (28) to a fractionation zone (29), preferably by atmospheric distillation, from which a fuel or diesel fraction is collected, comprising at least one second petroleum fraction (30), a second diesel fraction (31) and a second heavier than diesel fraction (32), also referred to as slurry. The second diesel fraction (31) is directed at least partially to fuel reservoirs (tanks) and/or is directed partially or completely via a line (33) to the diesel hydrotreating zone (18) in step e). The second fraction heavier than diesel (slurry) (32) is, for example, partially or completely directed to a heavy fuel oil reservoir (tank) and/or partially or completely directed back to the catalytic cracking stage (26) via a line (34). The second fraction heavier than diesel (32) is optionally partially or completely directed to the deasphalting unit (3) via a line (35).

Example

The hydrocarbon feedstock containing shale oil is processed, the properties of which are presented in Table 1.

Table 1: Properties of hydrocarbon feedstock containing shale oil

Shale oil, from which hydrocarbons containing less than 5 carbon atoms (C5) have been separated, is first subjected to atmospheric distillation, which separates the volatile products, diesel, kerosene and naphtha, which are processed in the refining chain according to their properties. The atmospheric distillation of shale oil also produces an atmospheric distillation residue, which mainly contains compounds with a boiling point above 350 °C. The atmospheric distillation residue in this example constitutes 40% by weight of the feedstock. This feedstock is deasphalted with propane at a solvent/feedstock ratio of 5/1, at a temperature of 100 °C and 4 MPa. The deasphalted oil and residue are obtained.

The deasphalted oil is processed in a fluidized bed reactor containing the commercial catalyst HOC 458 from Axens. The processing conditions are as follows:

- Reactor temperature: 425 °C

- Pressure: 19.5 MPa

- Hydrogen/raw ratio: 400 Nm3/m3

- Overall WHSV: 0.6 h-1

The liquid products obtained from the reactor are fractionated by atmospheric distillation into a petroleum fraction (hydrocarbons containing more than five carbons) (below 150 °C), a diesel fraction (150 °C - 370 °C) and a fraction heavier than diesel (above 370 °C), which forms a fraction heavier than diesel.

The petroleum fraction is hydrotreated in a fixed bed using a NiMo catalyst on alumina. The treatment conditions are as follows:

- Reactor temperature: 320 °C

- Pressure: 5 MPa

- Hydrogen/raw ratio: 400 Nm3/m3

- Overall WHSV: 1 h-1

The diesel fraction is hydrotreated in a fixed bed using a NiMo catalyst on alumina. The treatment conditions are as follows:

- Reactor temperature: 350 °C

- Pressure: 12 MPa

- Hydrogen/raw ratio: 400 Nm3/m3

- Overall WHSV: 0.6 h-1

The fraction heavier than the diesel fraction is then subjected to catalytic cracking using a catalyst containing 20 wt.% zeolite Y and 80 wt.% aluminosilicate matrix. This feedstock, previously heated to 135 °C, is brought into contact with the catalyst from the regenerator in the lower part of a vertical reactor, the catalyst having been regenerated by heating. The catalyst temperature at the reactor inlet is 720 °C. The catalyst flow rate to feedstock flow rate ratio is 6.0. The heat released by the catalyst at 720 °C enables endothermic feedstock vaporization and cracking reactions. The average residence time of the catalyst in the reaction zone is approximately 3 seconds. The pressure during processing is 0.18 MPa. The measured catalyst temperature at the end of the fluidized bed reactor with upward flow (riser) is 525 °C. The cracked hydrocarbons and the catalyst are separated by cyclones in the stripping zone, where the catalyst is removed. The catalyst, on which coke is deposited during the reaction, is sent to the regenerator after separation in the stripping zone. The solid coke (delta coke) content entering the regenerator is 0.85%. The coke is burned by air introduced into the reactor. The combustion, which is highly exothermic, raises the temperature of the solid from 525 °C to 720 °C. The hot regenerated catalyst leaves the regenerator and is returned to the bottom of the reactor.

The hydrocarbons separated from the catalyst exit the unloading zone. They are directed to the main fractionation tower, from the upper part of which the gas and oil fractions exit, then from the base of the tower in increasing boiling point order the second diesel fraction (LCO and HCO) and the second fraction heavier than the diesel fraction (slurry) (above 370 °C) exit.

Table 2 shows the properties of the different feedstocks in each stage, as well as the yields and total yields obtained in the different zones. Thus, it was found that starting from 100 wt% shale oil, 86.2 wt% fractions meeting Euro V commercial specifications (LPG, oil fraction, diesel fraction) are obtained.

Table 2

Claims (20)

1. A method for processing a hydrocarbon feedstock containing shale oil or a mixture of shale oils, with a nitrogen content of 0.1-3.0 wt%, characterized in that the method comprises the following steps: a) the feedstock is decontaminated, resulting in a residual fraction and a decontaminated oil, b) the decontaminated oil is directed to a hydroconversion zone in the presence of hydrogen, said zone comprising at least one fluidized bed reactor operating in an ascending gas and liquid flow and comprising at least one supported hydroconversion catalyst, c) the liquid product obtained in step b) is directed in part or in full to a fractionation zone, where a gas fraction, a petroleum fraction, a diesel fraction and a fraction heavier than a diesel fraction are obtained by atmospheric distillation, d) said petroleum fraction is treated in part or in full in a hydrotreatment zone in the presence of hydrogen, said zone comprising at least one fixed bed reactor comprising at least one hydrotreatment catalyst, and e) said diesel fraction is partially or completely treated in a second hydrotreating zone in the presence of hydrogen, said zone comprising at least one fixed bed reactor containing at least one hydrotreating catalyst. 2. The method according to claim 1, characterized in that the hydrotreating zone in step d) is different from the hydrotreating zone in step e) and the treatment conditions in the hydrotreating zone in step e) are different from the treatment conditions in the hydrotreating zone in step d). 3. The method according to claim 1, characterized in that the decontamination in step a) is carried out by deasphalting. 4. The method according to claim 1, characterized in that the nitrogen content of the hydrocarbon feedstock is 1 - 3 wt%. 5. The method according to claim 1, characterized in that the nitrogen content of the hydrocarbon feedstock is 2 - 3 wt%. 6. The method according to claim 1, characterized in that it further comprises a step f), in which the fraction heavier than diesel is partially or completely directed to step a) for decontamination. 7. A method according to any preceding claim, characterized in that the liquid product obtained in step b) is fractionated by atmospheric distillation into a gas fraction boiling below 50 °C, a petroleum fraction boiling between 50 °C and 150 °C, a diesel fraction boiling between 150 °C and 370 °C, and a fraction heavier than the diesel fraction boiling above 340 °C, preferably above 370 °C. 8. The method according to any preceding claim, characterized in that the decontamination in step a) is carried out with a solvent selected from the group consisting of propane, n-butane, isobutane, n-pentane, cyclopentane, 2-methylbutane, 2,2-dimethylpropane and mixtures thereof in any ratio. 9. The method according to any preceding claim, characterized in that the decontamination in step a) is carried out with a solvent/raw material ratio of 3/1 to 8/1, preferably 4/1 to 6/1, at a temperature between 60 °C and 250 °C, preferably between 60 °C and 200 °C, and at a pressure between 4 MPa and 5 MPa. 10. A method according to any preceding claim, characterized in that the fixed bed hydrotreating zones in step d) and step e) comprise a trap layer specific for arsenic compounds and silicon compounds upstream of the hydrotreating catalytic layers. 11. A method according to any preceding claim, characterized in that the fraction heavier than diesel is directed, in part or in whole, to a catalytic cracking zone, referred to as step g), where it is treated under conditions allowing the production of a second gas fraction, a second oil fraction, a second diesel fraction and a second fraction heavier than diesel. 12. The method according to claim 11, characterized in that the second fraction heavier than diesel obtained in step g) is partially or completely directed to step g). 13. The method according to claim 11, characterized in that the second diesel fraction obtained in step g) is partially or completely directed to step e) for the treatment of diesel with hydrogen. 14. The method according to claim 11, characterized in that the second fraction heavier than diesel obtained in step g) is partially or completely directed to step a) for decontamination. 15. The method according to any preceding claim, characterized in that the hydrogen conversion of step b) is carried out at a temperature in the range of 300 °C to 550 °C, preferably in the range of 400 °C to 450 °C, at a pressure in the range of 2 to 35 MPa, preferably in the range of 10 to 20 MPa, at a mass flow rate per hour in the range of 0.2 to 1.5 h-1 and at a hydrogen/raw material ratio in the range of 50 to 5000 Nm3/m3, preferably in the range of 100 to 1000 Nm3/m3. 16. The method according to any preceding claim, characterized in that the hydrotreating of the petroleum fraction in step d) is carried out at a temperature between 280 °C and 380 °C, preferably between 300 °C and 350 °C, at a pressure between 4 and 15 MPa, preferably between 10 and 13 MPa, at a mass flow rate per hour between 0.1 and 5 h-1, preferably between 0.5 and 1 h-1, and at a hydrogen/crude ratio between 100 and 5000 Nm3/m3, preferably between 100 and 1000 Nm3/m3. 17. The method according to any preceding claim, characterized in that the hydrogenation of the diesel fraction of step e) is carried out at a temperature between 320 °C and 450 °C, preferably between 340 °C and 400 °C, at a pressure between 7 and 20 MPa, preferably between 10 and 15 MPa, at a mass flow rate per hour between 0.1 and 1 h-1, preferably between 0.3 and 0.8 h-1, and at a hydrogen/crude ratio between 100 and 5000 Nm3/m3, preferably between 200 and 1000 Nm3/m3. 18. The method according to any preceding claim, characterized in that the catalysts for the hydrogen conversion of step b) and the hydrogenation of steps d) and e) are independently selected from the group of catalysts comprising a Group VIII metal selected from Ni and Co on an amorphous support selected from alumina, silica, aluminosilicates, magnesia, clays and mixtures thereof. 19. A method according to any preceding claim, characterized in that a hydrocarbon feedstock comprising shale oil or a mixture of shale oils is added to a hydrocarbon feedstock selected from the group consisting of oils obtained from coal, oils obtained from heavy tars and oil sands, vacuum distillates and straight-run distillation residues, vacuum distillates and crude residues obtained from residue treatment methods, solvent-deasphalted oils, light fraction oils, heavy fraction oils, diesel fractions obtained from catalytic cracking, the distillation range of which is 150 °C to 650 °C, aromatic extracts obtained from the production of lubricating oils, oils obtained from the pyrolysis of lignin-containing residues, crude oils obtained from biomass ("biocrudes"), vegetable oils and animal fats or mixtures of these hydrocarbon feedstocks. 20. Apparatus for processing a hydrocarbon feedstock containing shale oil, characterized in that the apparatus comprises: - a decontamination zone for the hydrocarbon feedstock containing shale oil to be processed, - a hydrogen conversion zone in the presence of hydrogen, comprising a fluidized bed reactor operating in an ascending gas-liquid flow and comprising at least one supported hydrogen conversion catalyst, - an atmospheric distillation fractionation zone, - a hydrogen treatment zone in the presence of hydrogen, comprising a fixed bed reactor comprising at least one hydrotreatment catalyst, - a second hydrogen treatment zone in the presence of hydrogen, comprising at least one fixed bed reactor comprising at least one hydrotreatment catalyst, these elements being operatively interconnected to carry out the method according to any one of claims 1 to 19.