RU2592690C2 - Method of converting hydrocarbon material containing shale oil by hydroconversion in fluidised bed, fractionation using atmospheric distillation and extraction liquid/liquid in heavy fraction - Google Patents

Abstract

FIELD: technological processes.

SUBSTANCE: present invention relates to a method of conversion of shale oil or a mixture of shale oil with nitrogen content at least 1 wt%. Method involves following steps: a) raw material is processed in a part of conversion in presence of hydrogen, wherein said part comprises at least one reactor with fluidised bed, which operates in mode of gaseous and liquid flow and comprising at least one catalyst on support; b) output stream obtained at step a) is fed, at least partially and frequently completely, into fractionation zone, from which, by means of atmospheric distillation, come out gaseous fraction, naphtha fraction, gas oil fraction and fraction heavier than gas oil; c) said naphtha fraction is processed, at least partially and frequently completely, in part for hydrotreatment in presence of hydrogen, wherein said part comprises at least one reactor with fixed layer, containing at least one hydraulic treatment catalyst; and d) said gas oil fraction is processed, at least partially and frequently completely, in other part for hydrotreatment in presence of hydrogen, wherein said part comprises at least one reactor with fixed layer, containing at least one hydraulic treatment catalyst; e) fraction heavier than gas oil fraction is subjected to liquid/liquid extraction to produce purified oil product and extract.

EFFECT: proposed method allows to obtain products of high quality with low content of sulphur and nitrogen.

16 cl, 2 dwg, 2 tbl, 1 ex

Description

The present invention relates to a method for converting shale oil-containing hydrocarbons into lighter products that can be used as fuel and / or petrochemical feedstocks. More specifically, the present invention relates to a method for converting a hydrocarbon feedstock containing shale oil, which comprises a fluidized bed hydroconversion feedstock step, followed by atmospheric distillation fractionation step to obtain a light fraction, a ligroin fraction and a gas oil fraction, and to obtain a heavier fraction, than the gas oil fraction, and the stage of extraction of the liquid / liquid fraction, heavier than the gas oil fraction, and specialized hydrotreatment for each of the ligroin and gas oil fractions. This method makes it possible to convert shale oils into a very high quality fuel base and, more specifically, has an excellent yield.

Due to the high volatility of prices per barrel and reduced detection of conventional areas of oil products, oil companies are turning to non-standard sources. Following oil and gas sands and deep-sea areas, oil shales, although relatively poorly known, are becoming increasingly desirable.

Oil shales are sedimentary rocks that contain an insoluble organic matter called kerogen. At a high temperature in situ or ex situ (“distillation in retort”) in the absence of air, at temperatures from 400 to 500 ° C, these shales give off oil, shale oil, a general form similar to crude oil.

Despite its composition other than crude oil, shale oils can be a substitute for the latter, as well as a source of chemical intermediates.

Shale oils cannot be directly used in place of crude oil. In fact, although these oils are similar to oil in some respects (for example, a similar H / C ratio), they differ in chemical nature and a much higher level of metallic and / or non-metallic impurities, thus making the conversion of this non-standard source much more complex than oil. Shale oils have, in particular, oxygen and nitrogen levels that are much higher than in oil. They may also contain higher concentrations of olefins, sulfur, or metal compounds (especially compounds containing arsenic).

Shale oils obtained by pyrolysis of kerogen contain a large number of olefin compounds obtained as a result of cracking, and this leads to the need for additional hydrogen at the stage of purification. For example, the bromine index, which makes it possible to calculate the concentration by weight of olefinic hydrocarbons (by adding bromine to the ethylene double bond), is usually greater than 30 g / 100 g of hydrocarbon feed for shale oils, while it is from 1 to 5 g / 100 g of hydrocarbon feed for oil residues. The olefin compounds resulting from cracking essentially consist of monoolefins and diolefins. The unsaturations present in olefins are a potential source of instability during polymerization and / or oxidation.

The oxygen content, as a rule, is higher than in heavy oil, and can be almost 8 wt.% From raw materials. Oxygen compounds are often phenols and carboxylic acids. Therefore, shale oils can have a noticeable acidity.

The sulfur content varies from 0.1 wt.% To 6.5 wt.%, Making strong desulfurization treatments necessary to meet the specifications for the fuel base. Sulfur compounds are in the form of thiophenes, sulfides or disulfides. Moreover, the sulfur distribution profile in shale oil may differ from that obtained in conventional oil.

The most distinctive feature of shale oils, however, is the higher nitrogen content, which makes them unsuitable as conventional raw materials for a refinery. Oil typically contains about 0.2 wt.% Nitrogen, while crude shale oils contain, as a rule, about 1 wt.% To about 3 wt.% Or more nitrogen. Moreover, nitrogen compounds present in oil are generally concentrated in relatively higher boiling ranges, while nitrogen compounds present in crude shale oils are generally distributed over all boiling ranges of the material. Nitrogen compounds in oil are mainly minor compounds, while, in general, about half of the nitrogen compounds present in crude shale oils are basic. These basic nitrogen compounds are particularly undesirable in petroleum refining feeds, as these substances often act as catalyst poisoning agents. In addition, product stability is a problem that is common to many products derived from shale oil. Such instability, including photosensitivity, as it turned out, is essentially the result of the presence of nitrogen compounds. Consequently, crude shale oils should typically undergo a strong refining treatment (high total pressure) in order to obtain synthetic crude oil or fuel base products that meet the current conditions.

It is also known that shale oils can contain many traces of metal compounds, generally present in the form of organometallic complexes. Metal compounds include common pollutants such as nickel, vanadium, calcium, sodium, lead or iron, as well as arsenic metal compounds. In fact, shale oils may contain more than 20 ppm of arsenic, while the amount of arsenic in crude oil typically lies in the ppm range (ppm). All of these metal compounds are catalyst poisoners. More specifically, they irreversibly poison hydroprocessing catalysts and hydrogenation catalysts by uniform deposition on the active surface. Conventional metal compounds and part of arsenic are found mainly in heavy fractions, and are removed by precipitation on the catalyst. On the other hand, when products containing arsenic are capable of creating volatile compounds, these compounds can be partially found in lighter fractions and, as a result, can poison the catalysts in subsequent conversion processes, during refining, or in petrochemicals.

In addition, shale oils typically contain sandy sediments originating from areas of tar shale, from which shale oils are extracted. These sand deposits can cause clogging problems, especially in fixed bed reactors.

Finally, shale oils may contain waxes that make their pour point higher than the ambient temperature, thus preventing them from moving in the pipeline.

In view of the significant resources and in view of their assessment as a promising source of oil, there is a true need for turning shale oils into light products that can be used as fuel and / or raw materials for petrochemicals. Methods for the conversion of shale oils are known. Conversion is usually carried out in practice, alternatively by coking, hydrocracking (thermal cracking in the presence of hydrogen) or by hydroconversion (catalytic hydrogenation). Liquid / liquid extraction processes are also known.

For example, US Pat. No. 4,483,763 discloses a method for converting shale oils by reducing their nitrogen content. This method includes a partial hydrogenation step followed by a liquid / liquid extraction step using a mixture of a polar organic solvent, acid and water. Extraction is carried out either on fractions of middle distillates (400-680 ° F = 204-360 ° C), or on the entire output obtained by hydrogenation.

US5059303 discloses a method for converting shale oils, which comprises a fluidized-bed or fixed-bed hydroconversion step, optionally a fractionation step, a liquid / liquid extraction step on a liquid fraction or on the entire liquid outlet with a solvent, thereby providing extraction of condensed aromatic substances . The refined oil obtained after evaporation of the solvent is then subjected to fractionation to obtain a middle distillate fraction containing up to 1000 ppm nitrogen and a heavier fraction containing from 500 to 3000 ppm nitrogen. US Pat. No. 5,059,303 also discloses a process variant that comprises a fluidized bed hydroconversion step, a gas / liquid separation step without reducing the pressure, a liquid / liquid extraction phase of the liquid phase, and a gaseous phase hydrotreatment step.

Object of the invention

The specific feature of shale oils, consisting of a certain number of metallic and / or non-metallic impurities, makes the conversion of this non-standard source much more difficult than oil. The industrial development of shale oil conversion methods therefore requires the development of methods that are suitable for raw materials that maximize high fuel base output quality. Conventional cleansing treatments known to oil should be adapted to the specific composition of shale oils.

The present invention contributes to the improvement of known methods for the conversion of hydrocarbon materials containing shale oil by increasing, in particular, the yield of the fuel base for a combination of steps having a specific bond and processing corresponding to each fraction obtained from shale oils. Similarly, it is an object of the present invention to provide high quality products having, more specifically, a low content of sulfur, nitrogen and arsenic, preferably as described. Another objective is to provide a method that is simple, that is, it has as few stages as necessary, while remaining efficient, allowing you to limit the cost of investment.

In its broadest form, the present invention relates to a method for the conversion of hydrocarbon feeds containing at least one shale oil having a nitrogen content of at least 0.1%, often at least 1% and very often at least 2 wt.%, Characterized in that it contains the following stages:

a) the feed is treated in a hydroconversion section in the presence of hydrogen, said section comprising at least one fluidized bed reactor operating in a gaseous and liquid ascending mode and containing at least one supported hydroprocessing catalyst;

b) the effluent obtained in stage a) is introduced, at least partially and often completely, into the fractionation zone, from which, through atmospheric distillation, a gaseous fraction, a ligroin fraction, a gas oil fraction and a heavier fraction than gas oil exit;

c) said fraction of naphtha is treated, at least partially and often completely, in a hydrotreatment portion in the presence of hydrogen, said portion comprising at least one fixed bed reactor comprising at least one hydrotreatment catalyst; and

d) said gas oil fraction is treated, at least partially and often completely, in another part for hydrotreatment in the presence of hydrogen, said part comprising at least one fixed-bed reactor containing at least one hydrotreatment catalyst;

e) a fraction heavier than the gas oil fraction is subjected to liquid / liquid extraction to obtain a purified oil product and extract.

In the part for processing in stage a), as a rule, from one to three, preferably two, reactors in series, and the part for processing in stages c) and d) also contains from one to three reactors in series.

The research work carried out by the authors on the conversion of shale oils led to the unexpected discovery that improving existing methods, in terms of fuel base output and in terms of product purity, is possible by combining various stages, connected in a special way, and the subsequent part for processing each fraction obtained by the method.

The first stage contains fluidized bed hydroconversion. The fluidized bed technique, relative to the fixed bed technique, facilitates the processing of raw materials that are heavily contaminated with metals, heteroatoms and sediments, such as shale oils, while exhibiting a conversion rate that is typically greater than 50%. In fact, in this first stage, shale oil turns into molecules that are capable of creating a fuel base in the future. Most metal compounds, residues and heterocyclic compounds are removed. The stream leaving the fluidized bed thus contains most of the stable nitrogen and sulfur compounds, and possibly the volatile arsenic compounds that are present in the lighter components.

The effluent obtained in the hydroconversion stage is then fractionated by atmospheric distillation, creating various fractions for which a treatment specific to each fraction is successively carried out. A key step in the method that is carried out is fractionation by atmospheric distillation before the liquid / liquid extraction step, to individually maximize the lighter fractions (naphtha, gas oil), subsequently making moderate hydrotreatment, which is adapted for each fraction, and minimize the fraction, more heavier than the gas oil fraction, necessitating a more rigorous treatment through liquid / liquid extraction. Thus, atmospheric distillation makes it possible to obtain various desired fractions (ligroin, gas oil) in one step, thus facilitating the downstream hydroprocessing adapted for each fraction and, therefore, the direct production of gas oil or naphtha fuel base products, which satisfy various specifications. Therefore, fractionation after hydroprocessing is not necessary.

Due to the high level of reduction of pollution in the fluidized bed, light fractions (naphtha and gas oil) contain less pollutants and can therefore be processed in parts with a fixed layer, which, as a rule, has improved hydrogenation kinetics compared to the fluidized bed. Similarly, operating conditions can be mild due to the limited pollutant content. Processing for each fraction allows better performance with respect to the desired products. Depending on the selected operating conditions (more or less strict), it is possible to obtain either a fraction that can be introduced into the fuel pool, or a final product that satisfies the current technical specifications (sulfur content, maximum smoke height, cetane, aromatic components, etc.). d.).

Upstream of the hydroprocessing catalyst bed, the fixed-bed hydroprocessing portions preferably contain specific protective layers for any arsenic compounds or silicon compounds contained within the diesel engine and / or naphtha. Arsenic compounds released from the fluidized bed (because they are usually relatively volatile) are captured by the protective layers, thus preventing the poisoning of downstream catalysts and contributing to the production of a very arsenic depleted fuel base.

Atmospheric distillation also promotes the conversion of most residual nitrogen compounds into a fraction heavier than gas oil, thus limiting the amount to be processed by liquid / liquid extraction. The equipment, as well as the amount of solvent required for the liquid / liquid extraction step, is thus minimized.

A fraction heavier than the diesel fraction obtained by the fractionation step is subjected to liquid / liquid extraction with a polar solvent. The solvent used is a solvent for preferential extraction of aromatic compounds. Since stable residual nitrogen is mainly localized in aromatic compounds, the liquid / liquid extraction step therefore contributes to the reduction of aromatic nitrogen compounds that are resistant to hydrodetotization (de-nitration by catalytic hydrogenation). It is also important that, unlike the prior art, liquid / liquid extraction is carried out only for the heavy fraction, in order to avoid loss of fuel base output during the extraction of the solvent after extraction. Products which it is desired to extract from the heavy fraction preferably have a boiling point higher than the boiling point of the solvent in order to avoid any yield loss during separation of the solvent from the refined oil after extraction. The reason is that during the separation of the solvent from the refined oil product, any compound having a boiling point less than the boiling point of the solvent will inevitably go away with the solvent, and therefore a smaller amount of refined oil will be obtained (and therefore a lower fuel base yield) . In the case of furfural, as a solvent for extraction, for example, having a boiling point of 162 ° C, C10 ^- compounds, compounds that represent the gasoline / naphtha fraction will be lost. By treating only the heavy fraction comprising compounds having a boiling point higher than the boiling point of the solvent for extraction, there is no loss of C10 ^- compounds. Moreover, contamination of the solvent with C10 ^- compounds does not occur, and stages of processing of this solvent for recycling are possible. Solvent recovery, therefore, is more efficient and economical.

Another advantage of the method is the fact that the refined oil obtained in the liquid / liquid extraction step e), followed by evaporation of the solvent, is preferably introduced into the catalytic cracking section [step f)], in which it is processed under conditions that contribute to the production of gaseous fraction, gasoline fraction, gas oil fraction and residual heavy fraction, which is referred to as "suspension". This option contributes to the exit of the fuel base to be maximized.

Another advantage is the fact that the extract obtained after liquid / liquid extraction can be at least partially recycled to the hydroconversion step a). Recycling helps increase fuel base output.

DETAILED DESCRIPTION OF THE INVENTION

Hydrocarbon feed

The hydrocarbon feed contains at least one shale oil or a mixture of shale oils. The term "shale oil" is used in this application in its broadest sense and is intended to include any shale oil or a fraction of shale oil that contains nitrogen impurities. It includes crude shale oil, obtained either by pyrolysis, by extraction with a solvent, or other means, or shale oil that has been filtered to remove solids, or which has been treated with one or more solvents, chemicals or other treatments, and which contains nitrogen impurities. The term “shale oil” also contains shale oil fractions obtained by distillation or another fractionation technique.

The shale oils used according to the present invention typically have a Conradson carbon residue of at least 0.1 wt.% And, as a rule, at least 5 wt.%, An asphaltene content (IP143 standard / s C7) of at least 1 %, often at least 2 wt.%. The sulfur content in them, as a rule, is at least 0.1%, often at least 1% and very often at least 2%, and even up to 4% or even 7 wt.%. The amount of metals that they contain is typically at least 5 parts per million, often at least 50 parts per million, and typically at least 100 parts per million, or at least 200 parts by weight per million. The nitrogen content in them, as a rule, is at least 0.5%, often at least 1% and very often at least 2 wt.%. The arsenic content in them, as a rule, is greater than 1 mass parts per million and up to 50 mass parts per million.

The method according to the present invention is intended for the conversion of shale oils. However, the feed may optionally contain, in addition to shale oil, other synthetic liquid hydrocarbons, more particularly those containing a substantial amount of cyclic organic nitrogen compounds. These include oils derived from coal, oils based on heavy resins, tar sands, pyrolytic oils from wood residues such as wood residues, crude oil derived from biomass (“bio-raw materials”), vegetable oils and animal fats.

Other hydrocarbon feedstocks may also provide shale oil. The feedstock is selected from the group consisting of vacuum distillates and direct distillation residues, vacuum distillates and unconverted residues obtained during conversion processes, such as, for example, obtained during distillation to a coke point (coking), products obtained from hydroconversion of heavy fractions with a fixed layer of products obtained from the hydroconversion process of heavy fractions with a fluidized bed, and oils deasphalted using solvents (for example, oils deasphalted with propane, butane and foam tan, occurring during the process of deasphalting of vacuum residues of direct distillation or vacuum residues obtained from hydroconversion processes).

The feed may further comprise light cyclic oil (LCO) of various origins, heavy cyclic oil (LCO) of various origins, and gas oil fractions that originate from catalytic cracking and typically have a distillation range of from about 150 ° C to about 650 ° C . The feed may also contain aromatic extracts obtained from the production of lubricating oils. Raw materials can also be obtained and used in mixtures, in any proportions.

Hydrocarbons added to shale oil or to a mixture of shale oils can comprise from 20% to 60% by weight of all raw materials (shale oil or a mixture of shale oils + added hydrocarbons), or from 10% to 90% by weight.

Hydroconversion

According to the present invention, the feed is primarily subjected to a fluidized bed hydroconversion step [step a)]. Hydroconversion is understood as hydrogenation, hydrotreatment, hydrodesulfurization, hydrodenitrogenation, hydrodemetallization and hydrocracking reactions.

The operation of a fluidized bed catalytic reactor, including the recycling of liquids from the reactor to the top through a stirred catalytic bed, is well known. Fluidized bed techniques employ catalysts on a substrate, typically in the form of extrudates having a diameter of typically about 1 mm or less than 1 mm, for example greater than or equal to 0.7 mm. Catalysts remain inside reactors and are not removed with products. The catalytic activity may remain constant due to the continuous substitution (addition and withdrawal) of the catalyst. Therefore, there is a need to shut down the assembly in order to replace the used catalyst, or to increase the reaction temperature during the cycle to compensate for deactivation. Moreover, working with constant working conditions makes it possible to coordinate product quality and yields obtained per catalyst cycle. Since the catalyst is kept in a state of mixing through substantial liquid recycling, the pressure loss across the reactor remains low and constant, and the heat of reaction is quickly averaged over the catalyst bed, which is therefore almost isothermal and does not require cooling by injection of quenchers. The fluidized bed hydroconversion avoids the problems of catalyst contamination associated with the deposition of impurities naturally present in shale oils.

The conditions in step a) of processing the feed in the presence of hydrogen are standard fluidized bed hydroconversion conditions for a fraction of liquid hydrocarbons. They usually operate at a total pressure of from 2 to 35 MPa, preferably from 10 to 20 MPa, at a temperature of from 300 ° C to 550 ° C and often from 400 ° C to 450 ° C. The hourly average feed rate (HSV) and the partial pressure of hydrogen are important factors that are selected according to the characteristics of the product to be processed and the desired conversion. HSV, as a rule, lies in the range from 0.2 h ^-1 to 1.5 h ^-1 and preferably from 0.4 h ^-1 to 1 h ^-1 . The amount of hydrogen mixed with the feed is typically from 50 to 5000 normal cubic meters (Nm ³ ) per cubic meter (m ³ ) of liquid feed, and typically from 100 to 1000 Nm ³ / m ³ , and preferably from 300 to 500 Nm ³ / m ³ .

This hydroconversion step a) can typically be carried out under the conditions of the T-STAR® process, as described, for example, in Heavy Oil Hydroprocessing, published by AlChE, March 19-23, 1995, Houston, Texas, paper number 42d. It can also be carried out under the conditions of the H-OIL® process, as described, for example, in an article published by NPRA, Annual Meeting, March 16-18, 1997, J.J. Colyar and L.I. Wisdom called The H-Oil® Process, A Worldwide Leader In Vacuum Residue Hydroprocessing.

The hydrogen required for hydroconversion (and subsequent hydrotreatment operations) can come from steam reforming of hydrocarbons (methane) or from gas obtained from oil shale during the production of shale oils.

The catalyst in step a) is preferably a conventional granular hydroconversion catalyst containing, on an amorphous support, at least one metal or metal compound having (having) a hydrodehydrogenation function. Generally speaking, the catalyst is used whose pore distribution is suitable for processing raw materials containing metals.

The hydrodehydrogenation function may be provided by at least one group VIII metal selected from the group consisting of nickel and / or cobalt, optionally in combination with at least one group VIB metal selected from the group consisting of molybdenum and / or tungsten . It is possible, for example, to use a catalyst containing from 0.5% to 10 wt.% Nickel and preferably from 1% to 5 wt.% Nickel (in the form of nickel oxide, NiO) and from 1% to 30 wt.% Molybdenum, preferably from 5 % to 20 wt.% molybdenum (in the form of molybdenum oxide, MoO ₃ ), on an amorphous inorganic substrate. The total amount of metal oxides of groups VIB and VIII is often from 5% to 40 wt.% And in general from 7% to 30 wt.%. The mass ratio, expressed as a Group VI metal oxide (or metals) to a Group VIII metal oxide (or metals), is typically from about 20 to about 1 and, as a rule, from about 10 to about 2.

The catalyst support will be selected, for example, from the group consisting of alumina, silica, aluminosilicates, magnesium oxide, clays and mixtures of at least two of these minerals. This substrate may also include other compounds, for example, oxides selected from the group consisting of boron oxide, zirconium oxide, titanium oxide and phosphoric anhydride. Typically, an alumina support is used, and very often an alumina support doped with phosphorus and, if necessary, boron. In this case, the concentration of phosphoric anhydride, P ₂ O ₅ , is usually less than about 20 wt.% And usually less than about 10 wt.%, And at least 0.001 wt.%. The concentration of boron trioxide, B ₂ O ₃ , as a rule, is from about 0% to about 10 wt.%. The alumina used is typically γ (gamma) or η (this) alumina. This catalyst is typically used in the form of an extrudate. The catalyst in step a) is preferably based on nickel and phosphorus doped molybdenum and on an alumina support. An HTS 458 catalyst sold by Axens may be used, for example.

Prior to the introduction of the feed, the catalysts used in the process of the present invention are preferably subjected to a sulfurization treatment to convert at least a portion of the metal groups to sulfides before they come into contact with the feed to be treated. This activating treatment by sulfurization is well known to specialists in this field of technology and can be carried out by a method already described in the literature, either in situ, i.e. inside the reactor, or ex situ.

The spent catalyst is often replaced with a fresh catalyst by withdrawing from the bottom of the reactor and introducing fresh or new catalyst at the top of the reactor, at regular intervals, for example by conventional or quasi-continuous addition. It is possible, for example, to introduce a fresh catalyst every day. The replacement level of the spent catalyst with a fresh catalyst can be, for example, from about 0.05 kg to about 10 kg per m ^{3 of} feedstock. This conclusion and this substitution are carried out using devices that provide continuous operation of this stage of hydroconversion. The assembly typically comprises a recirculation pump to maintain the fluidized bed catalyst by continuously recirculating at least a portion of the liquid removed from the top of the reactor and re-entering it at the bottom of the reactor. It is also possible to transport spent catalyst discharged from the reactor to a regeneration zone in which the carbon and sulfur that it contains are removed, and then introduce this regenerated catalyst back to the hydroconversion step a).

Operating conditions associated with catalytic activity provide possible degrees of conversion of the feed from 50% to 95%, preferably from 70% to 95%. The above conversion is defined as the mass fraction of the feed at the beginning of the reaction minus the mass fraction, the heavy fraction having a boiling point of more than 343 ° C, at the end of the reaction, this value being divided by the mass fraction of the feed at the beginning of the reaction.

The fluidized bed technique allows the processing of raw materials that are heavily contaminated with metals, sediments and heteroatoms without the problems of pressure loss or clogging problems that are known when using a fixed layer. Metals, such as nickel, vanadium, iron and arsenic, are largely removed from the feed by precipitation on the catalysts during the reaction. Removable (volatile) arsenic will be removed at the hydrotreatment stages using specific protective layers. Sediments present in shale oils are also removed by replacing the catalyst in a fluidized bed without disrupting hydroconversion reactions. These stages also provide removal, hydrodenitrogenation, of the main part of nitrogen, leaving only the majority of stable nitrogen compounds.

The hydroconversion in step a) makes it possible for the resulting output stream to contain no more than 3,000 mass parts per million nitrogen, preferably no more than 2,000 mass parts per million nitrogen.

Atmospheric distillation fractionation

The effluent obtained from the hydroconversion stage is introduced at least partially, and preferably completely, into the fractionation zone from which the gaseous fraction, naphtha, gas oil fraction and a fraction heavier than the gas oil fraction are separated by atmospheric distillation.

The effluent obtained in stage a) is preferably fractionated by atmospheric distillation into a gaseous fraction having a boiling point of less than about 50 ° C, a naphtha boiling from about 50 ° C to about 150 ° C, a gas oil fraction boiling from about 150 ° C to about 370 ° C, and a fraction that is heavier than the gas oil fraction, and which typically boils at a temperature above 340 ° C, preferably at a temperature above 370 ° C.

Ligroin and diesel fractions are then separately introduced into the parts for hydroprocessing. The heavy fraction is subjected to liquid / liquid extraction.

The gaseous fraction contains gases (H ₂ , H ₂ S, NH ₃ , H ₂ O, CO ₂ , CO, C ₁ -C ₄ hydrocarbons, etc.). It can preferably be purified to recover hydrogen and to recycle it into the hydroconversion part in step a) or the hydrotreatment part in steps c) and d). After purification, C ₃ and C ₄ hydrocarbons can be used to form LPG (liquefied petroleum gas) products. Non-condensed gases (C ₁ -C ₂ ) are typically used as internal fuel for heating furnaces in hydroconversion and / or hydrotreatment reactors.

Hydrotreating ligroin and gas oil fractions

The ligroin and gas oil fractions are then separately hydrotreated with a fixed bed [steps c) and d)]. Hydrotreating refers to hydrodesulfurization, hydrodenitrogenation and hydrodemetallization reactions. The task, depending on the working conditions, which are chosen more or less strict, is to obtain various fractions according to the technical conditions (sulfur content, maximum height of the non-soaking flame, cetane, aromatic content, etc.) or to obtain synthetic crude oil. Processing ligroin in one part for hydroprocessing and a fraction of gas oil in another part for hydroprocessing provides improved performance in terms of operating conditions, so as to ensure that each fraction meets the required technical conditions with a maximum output and in one stage per fraction. Thus, fractionation after hydroprocessing is not necessary. The difference between the two parts for hydroprocessing is more based on differences in operating conditions than on the choice of catalyst.

The fixed-bed hydroprocessing portions preferably comprise upstream specific catalyst layers for the arsenic compounds (arsenic containing compounds) and silicon compounds that are optionally present in naphtha and / or diesel fractions. Compounds containing arsenic released from the fluidized bed (being, as a rule, relatively volatile) are captured by the protective layers, thus preventing the poisoning of catalysts located downstream and making it possible to obtain a fuel base that is very depleted in arsenic

Protective layers that remove arsenic and silicon from fractions of naphtha or gas oil are well known to those skilled in the art. They contain, for example, an absorbent material containing nickel deposited on an appropriate substrate (silica, magnesium oxide or alumina), as described in FR 2617497, or else an absorbent material containing copper on a substrate, as described in FR 2762004. mention protective layers supplied by Axens: ACT 979, ACT 989, ACT 961, ACT 981.

The operating conditions in each hydroprocessing unit are adapted for the raw material to be processed. The operating conditions for hydrotreatment of naphtha are generally milder than the operating conditions for hydrotreating a gas oil fraction.

At the hydrotreatment stage, ligroin [stage c)] is usually operated at absolute pressure from 4 to 15 MPa, often from 10 to 13 MPa. The temperature during this step c) is usually from 280 ° C to 380 ° C, often from 300 ° C to 350 ° C. This temperature is usually set in accordance with the desired level of hydrodesulfurization. The hourly average feed rate (HSV) is typically in the range from 0.1 h ^-1 to 5 h ^-1 , and preferably from 0.5 h ^-1 to 1 h ^-1 . The amount of hydrogen mixed with the feed is typically from 100 to 5000 normal cubic meters (Nm ³ ) per cubic meter (m ³ ) of liquid feed, and typically from 200 to 1000 Nm ³ / m ³ , and preferably from 300 to 500 Nm ³ / m ³ . It is useful to work in the presence of hydrogen sulfide (for sulfurization of the catalyst), and the partial pressure of hydrogen sulfide is usually from 0.002 times to 0.1 times, and preferably from 0.005 times to 0.05 times the total pressure.

At the hydroprocessing stage, gas oil fractions [stage d)] usually operate at an absolute pressure of from 7 to 20 MPa, often from 10 to 15 MPa. The temperature during this step c) is usually from 320 ° C to 450 ° C, often from 340 ° C to 400 ° C. This temperature is usually set in accordance with the desired level of hydrodesulfurization. Mass hourly consumption ((feed time / hour) / catalyst time) is from 0.1 to 1 h ^-1 . The hourly average feed rate (HSV) is typically in the range from 0.2 h ^-1 to 1 h ^-1 and preferably from 0.3 h ^-1 to 0.8 h ^-1 . The amount of hydrogen mixed with the feed is typically from 100 to 5000 normal cubic meters (Nm ³ ) per cubic meter (m ³ ) of liquid feed, and typically from 200 to 1000 Nm ³ / m ³ , and preferably from 300 to 500 Nm ³ / m ³ . It is useful to work in the presence of hydrogen sulfide (for sulfurization of the catalyst), and the partial pressure of hydrogen sulfide is usually from 0.002 times to 0.1 times, and preferably from 0.005 times to 0.05 times the total pressure.

In parts for hydroprocessing, an ideal catalyst should have a high hydrogenating ability so as to produce thoroughly refined products and achieve a significant reduction in sulfur and nitrogen. In a preferred embodiment of the present invention, the hydroprocessing parts operate at a relatively low temperature, which facilitates careful hydrogenation and limits coking of the catalyst. The use of one catalyst or two or more different catalysts, simultaneously or sequentially, in parts for hydroprocessing will not go beyond the scope of the present invention. The hydrotreatment in steps c) and d) is usually carried out industrially in one or more liquid downstream reactors.

In two parts, the same type of catalyst is used for the hydrotreatment [steps c) and d)]; the catalysts in each part may be the same or different. At least one fixed bed of a conventional hydrotreating catalyst is used, comprising, on an amorphous substrate, at least one metal or metal compound having a hydrodehydrogenation function.

The hydrodehydrogenation function may be provided by at least one group VIII metal selected from the group consisting of nickel and / or cobalt, optionally in combination with at least one group VIB metal selected from the group consisting of molybdenum and / or tungsten . It is possible, for example, to use a catalyst containing from 0.5% to 10 wt.% Nickel and preferably from 1% to 5 wt.% Nickel (in the form of nickel oxide, NiO) and from 1% to 30 wt.% Molybdenum, preferably from 5 % to 20 wt.% molybdenum (in the form of molybdenum oxide, MoO ₃ ), on an amorphous inorganic substrate. The total amount of metal oxides of groups VIB and VIII is often from 5% to 40 wt.% And in general from 7% to 30 wt.%. The mass ratio, expressed as a Group VI metal oxide (or metals) to a Group VIII metal oxide (or metals), is typically from about 20 to about 1 and, as a rule, from about 10 to about 2.

The catalyst support will be selected, for example, from the group consisting of alumina, silica, aluminosilicates, magnesium oxide, clays and mixtures of at least two of these minerals. This substrate may also include other compounds, for example, oxides selected from the group consisting of boron oxide, zirconium oxide, titanium oxide and phosphoric anhydride. Typically, an alumina support is used, and very often an alumina support doped with phosphorus and, if necessary, boron. In this case, the concentration of phosphoric anhydride, P ₂ O ₅ , is usually less than about 20 wt.% And usually less than about 10 wt.% And at least 0.001 wt.%. The concentration of boron trioxide, B ₂ O ₃ , as a rule, is from about 0% to about 10 wt.%. The alumina used is typically γ (gamma) or η (this) alumina. This catalyst is typically used in the form of extrudates.

Prior to introducing the feed, the catalysts used in the process of the present invention may be subjected to a sulfurization treatment to convert, at least in part, the metal groups to sulfides before they come into contact with the feed to be treated. This activating treatment by sulfurization is well known to specialists in this field of technology and can be carried out by a method already described in the literature, either in situ, i.e. inside the reactor, or ex situ.

Hydrotreating in step c) of the ligroin fraction results in a fraction containing not more than 1 parts by weight per million nitrogen, preferably not more than 0.5 parts by weight per million nitrogen, and not more than 5 parts by weight per million sulfur, preferably not more than 0.5 parts by weight parts per million sulfur.

The hydrotreatment in step d) of the gas oil fraction results in a fraction containing not more than 100 parts by mass per million nitrogen, and not more than 20 parts by mass of nitrogen, and not more than 50 parts by mass of sulfur, preferably not more than 10 parts by mass parts per million sulfur.

Liquid / Liquid Extraction

A fraction heavier than the gas oil fraction that leaves the fractionation portion by atmospheric distillation is then sent to the liquid / liquid extraction step [step e)]. The objective of this stage is the extraction of aromatic compounds, including residual nitrogen, from the heavy fraction, to obtain a refined oil product, which can be used as raw material for catalytic cracking in a unit for catalytic cracking with a fluidized bed. This makes it possible to maximize the output of the fuel base. Accordingly, liquid / liquid extraction provides a value obtained from a fraction that is typically very resistant to hydrotreatment.

The extraction is carried out by means of a solvent, which is known for the predominant extraction of aromatic compounds. As a solvent, it is possible to use furfural, N-methyl-2-pyrrolidone (NMP), sulfolane, dimethylformamide (DMF), dimethyl sulfoxide (DMSO), phenol or a mixture of these solvents in equal or different proportions.

Liquid / liquid extraction may be carried out by methods known to those skilled in the art. Extraction is usually carried out in a mixer-settler or in an extraction column. The extraction is preferably carried out in an extraction column.

Operating conditions, as a rule, is the ratio of solvent / raw materials equal to from 1/1 to 3/1, preferably from 1/1 to 1.8 / 1, the temperature profile from ambient temperature to 150 ° C, preferably from 50 ° C to 150 ° C. The pressure is between atmospheric pressure and 2 MPa, preferably between atmospheric pressure and 1 MPa.

The solvent has a boiling point that is high enough to allow the heavy fraction obtained after fractionation to liquefy without evaporation, and the heavy fraction is usually carried out at temperatures from 200 ° C to 300 ° C.

After the solvent contacts the heavy fraction, two phases form: (i) an extract consisting of parts of the heavy fraction which are insoluble in the solvent (and with a high concentration of aromatic substances containing residual nitrogen), and (ii) a refined oil product consisting of solvent and soluble fraction, which is the raw material from which the product can be obtained by catalytic cracking to increase the yield of the fuel base. The solvent is separated by distillation from the soluble parts and recycled within the liquid / liquid extraction process; solvent handling is known to those skilled in the art.

By extraction, a refined oil product is obtained containing not more than 1500 ppm, preferably not more than 1000 ppm, of nitrogen. At least a portion, and preferably a total volume, of the refined oil obtained from liquid / liquid extraction is preferably introduced to the catalytic cracking step.

According to a preferred embodiment, at least part and preferably the entire volume of the extract obtained in the liquid / liquid extraction step e) is recycled to the beginning of step a).

According to another embodiment of the present invention, the extract is introduced into the part of the vapor-oxygen gasification, in which 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 through the Fischer-Tropsch reaction. This mixture, in the context of the present invention, is preferably introduced into the “shear” conversion section (steam conversion), in which, in the presence of steam, it is converted to hydrogen and carbon dioxide. The obtained hydrogen can be used in stages a), c) and d) of the method according to the present invention. The extract obtained in step e) can also be used as a solid fuel or, after fluxing, as a liquid fuel, or may form part of a composition of bitumen (after an optional purge step) and / or heavy fuel oils.

The liquid / liquid extraction of the heavy fraction, therefore, makes it possible to extract stable aromatic compounds containing nitrogen and pollutants (metals). The implementation of extraction only in relation to the heavy fraction makes it possible to prevent losses of raw materials for catalytic cracking and, thus, increase the overall yield of the method. The recycling of the extract to the hydroconversion stage a) also provides an increase in yield.

Catalytic cracking

Finally, according to the aforementioned embodiment, in catalytic cracking [step f)], at least a portion, preferably an entire volume, of the refined oil obtained in step e) can be introduced, after evaporation of the solvent, into a portion for conventional catalytic cracking, in which The refined oil product is processed in the usual way, under conditions well known to a person skilled in the art, to obtain a gaseous fraction, a gasoline fraction, a gas oil fraction and a fraction heavier than the gas oil mentioned as a "suspension". The gas oil fraction will, for example, be at least partially introduced into the fuel tanks (pools) and / or recycled, at least partially, or even completely, to the gas oil hydrotreatment step d). A fraction heavier than gas oil will, for example, be at least partially or even completely introduced into the heavy fuel oil reservoir (pool) and / or recycled, at least partially, or even completely, to the catalytic cracking step f) . In the context of the present invention, the expression “conventional catalytic cracking” encompasses cracking methods that comprise at least one stage of catalyst regeneration by partial combustion, and methods that comprise at least one stage of catalyst regeneration by complete combustion, and / or methods comprising at least one stage of partial combustion, and at least one stage of complete combustion.

For example, a general description of catalytic cracking (the first industrial use of which occurred in 1936 (the Houdry process) or in 1942 when using a catalyst in a fluidized bed) can be found in Ullmans Encyclopedia of Industrial Chemistry Volume A 18, 1991, pages 61-64. It is common to use standard catalysts containing a matrix, optionally an additive and at least one zeolite. The amount of zeolite varies, but usually ranges from about 3% to about 60 wt.%, Often from about 6% to about 50 wt.%, And from about 10% to 45 wt.% Are usually used. Zeolite is usually dispersed in a matrix. The amount of additive is usually from about 0% to about 30 wt.%. The amount of matrix is the residue necessary to achieve 100 wt.%. The additive is typically selected from the group consisting of metal oxides from group IIA of the periodic table of elements, such as magnesium oxide or calcium oxide, rare earth oxides and metal titanates from group IIA. The matrix is typically silica, alumina, aluminosilicate, magnesium silicate, clay, or a mixture of two or more of these products. The most commonly used zeolite is zeolite Y. Cracking is carried out in a substantially vertical reactor, in either upflow or downflow mode. The choice of catalyst and operating conditions depends on the target products, depending on the raw materials being processed, as described, for example, in M. Marcilly article, pages 990-991 published in Institut Francais du Petrole, Nov.-Dec. 1975, pages 969-1006. Usually operate at temperatures from 450 ° C to 600 ° C with a residence time of less than 1 minute, often from about 0.1 to about 50 seconds.

The catalytic cracking step f) may also be a catalytic cracking stage with a fluidized bed, for example, according to the method designated R2R. This step can be carried out in the usual manner, as is known to those skilled in the art, under suitable cracking conditions to produce low molecular weight hydrocarbon products. A description of the mode and catalysts that can be used in the context of fluidized bed cracking in this step e) are described, for example, in patent documents US-A-5286690, US-A-5324696 and EP-A-699224.

The catalytic cracking reactor with a fluidized bed can operate in upstream mode or in a downward flow mode.

Although this is not a preferred embodiment of the present invention, in a similar manner, it is possible to consider the implementation of catalytic cracking in a moving bed reactor. Particularly preferred catalytic cracking catalysts are catalysts containing at least one zeolite, usually in admixture with a suitable matrix, such as, for example, alumina, silica or aluminosilicate.

1 schematically shows a method according to the present invention. Figure 2 schematically shows a variant of the method, which includes the stage of catalytic cracking.

According to FIG. 1, a feed containing shale oil (1) to be treated is introduced via line (21) to the fluidized bed hydroconversion section (2) in the presence of hydrogen (3), and hydrogen (3) is introduced via line ( 33). The stream leaving the fluidized bed hydroconversion section (2) is introduced via line (23) into the atmospheric distillation column (4), at the end of which a gaseous fraction (30), a ligroin fraction (25), a gaseous fraction (27) exit and fraction (29), heavier than the ligroin fraction. The gaseous fraction (30) containing hydrogen can be purified (not shown) to recycle hydrogen and introduce it into the fluidized-bed hydroconversion section (2) along line (33) and / or the hydroprocessing section (6) and / or (8) along the lines (35) and (37). The naphtha fraction (25) is introduced into the hydrotreatment unit with a fixed layer (6), at the end of which the naphtha fraction (13) comes out, depleted in impurities. The gas oil fraction (27) is introduced into the hydrotreatment section with a fixed layer (8), at the end of which the gas oil fraction (15) is depleted of impurities. Two parts for hydroprocessing (6) and (8) are fed with hydrogen along lines (35) and (37). The fraction heavier than the ligroin fraction (29) is sent to the liquid / liquid extraction stage (10) to extract aromatic substances. This extraction step is carried out by means of a solvent (not shown) and results in a purified oil product (17) and an extract (19). Extract (19), along line (39), can be used as fuel or to power the gasification unit for the production of hydrogen and energy. It can also be recycled to the hydroconversion unit (2) along line (31).

In Fig.2, the stages of hydroconversion, separation and hydroprocessing (and reference symbols) are identical to those shown in Fig.1. The refined oil product (17) obtained in the liquid / liquid extraction step can be sent to the catalytic cracking unit (12). The stream leaving this part is sent via line (43) to the fractionation part (14), preferably by atmospheric distillation, from which fuel or middle distillate fractions containing at least one gasoline fraction (45), one gas oil fraction ( 47) and one heavy fraction (51). The gas oil fraction (47) is introduced at least partially into the fuel tanks (pools) and / or recycled, at least partially or even completely, to the gas oil hydrotreatment stage d) (8) via line (49). The heavy fraction (“suspension”) (51), for example, at least partially or even completely, is introduced into the tank for heavy fuel oil (pool) and / or recycled, at least partially or even completely, to the catalytic cracking stage (12 ) along line (53).

Example

Process shale oil, which has the characteristics shown in Table 1.

Table 1 Characteristics of oil based on shale oil Density 15/4 - 0.951 Hydrogen wt.% 10.9 Sulfur wt.% 1.9 Nitrogen wt.% 1.8 Oxygen wt.% 2.7 Asphaltenes wt.% 3.7 Conradson carbon residue wt.% 4.5 Metals Ppm 236

Shale oil is treated in a fluidized bed reactor containing Axens industrial catalyst HTS458. The operating conditions are as follows:

- Temperature in the reactor: 425 ° C

- Pressure: 195 bar (19.5 MPa)

- The ratio of hydrogen / raw materials: 400 Nm ³ / m ³

- Total HSV: 0.3 h ^-1

Liquid products obtained from the reactor are fractionated by atmospheric distillation to obtain a naphtha fraction (C5 + - 150 ° C), a gas oil fraction (150-370 ° C) and a residual fraction of 370 ° C +.

The ligroin fraction is subjected to fixed-bed hydroprocessing using a NiMo catalyst on alumina. The operating conditions are as follows:

- Temperature in the reactor: 320 ° C

- Pressure: 50 bar (5 MPa)

- The ratio of hydrogen / raw materials: 400 Nm ³ / m ³

- Total HSV: 1 h ^-1

The gas oil fraction is subjected to fixed-bed hydroprocessing using a NiMo catalyst on alumina. The operating conditions are as follows:

- Temperature in the reactor: 350 ° C

- Pressure: 120 bar (12 MPa)

- The ratio of hydrogen / raw materials: 400 Nm ³ / m ³

- Total HSV: 0.6 h ^-1

The residual fraction is subjected to liquid / liquid extraction using furfural, with a solvent / feed ratio of 1.8 / 1, at a temperature of 100 ° C and at atmospheric pressure. This provides a refined oil product and extract.

The refined oil is then subjected to catalytic cracking using a catalyst containing 20 wt.% Zeolite Y and 80 wt.% Aluminosilicate matrix. This feedstock, preheated to 135 ° C, is introduced at the bottom of a vertical reactor with a catalyst from a regenerator, the catalyst being regenerated under hot conditions. The inlet temperature of the catalyst in the reactor is 720 ° C. The ratio of the catalyst flow rate to the feed flow rate is 6.0. The thermal contribution of the catalyst at 720 ° C promotes the evaporation of the feed and the cracking reaction, and both are endothermic. The average residence time of the catalyst in the reaction zone is about 3 seconds. The working pressure is 1.8 absolute bar. The temperature of the catalyst, measured at the end of a step-up controlled (vertical) fluidized bed reactor, is 525 ° C. Cracked hydrocarbons and the catalyst are separated by cyclones located in the distillation zone (evaporation column), in which the catalyst is distilled off. The catalyst, which is charged with coke during the reaction and then distilled off in the distillation zone, is then introduced into the regenerator. The coke solids content (delta coke) at the beginning of the regenerator is 0.85%. This coke is burned by air introduced into the regenerator. Combustion, which is highly exothermic, raises the temperature of a solid from 525 ° C to 720 ° C. The hot regenerated catalyst exits the reactor and again enters the bottom of the reactor.

Hydrocarbons separated from the catalysts leave the stripping zone. They are sent to the main fractional distillation column, at the top of which gases and gasoline fractions exit, and then, at the bottom of the column, to increase the boiling point, the LCO and HCO fractions and suspension (370 ° C +) exit.

Table 2 summarizes the properties of the various feedstocks at each stage, as well as the yields obtained at various sites, and the total yield. Therefore, it is observed that, based on 100% by weight of shale oil, 87.2% by weight of products (LPG, naphtha, middle distillates) are obtained that meet Euro V specifications.

table 2 Knot Fluidized bed Extraction Refined Oil Product Extract Total FCC Raw Raw Material Properties Shale oil Heavy fluidized bed fraction Refined Oil Product Extract starting point
fractions (° C) ° C C5 + 360+ 360+ 360+ Total shale oil yield wt.% one hundred 15.0 8.1 6.9 Density 15/4 - 0.951 0.926 0.899 0.960 Sulfur wt.% 1.9 0.25 0.12 0.40 Total nitrogen wt.% 1.8 0.60 0.11 1.14 Output of each node (liquefied petroleum gas, LPG) wt.% 2.4 10.0 naphtha wt.% 23.0 55.0 Middle distillates wt.% 55.5 14.0 Unconverted oil wt.% 15.0 Total shale oil yield (liquefied petroleum gas, LPG) wt.% 2.4 0.8 3.2 naphtha wt.% 23.0 4.4 27.4 Middle distillates wt.% 55.5 1.1 56.6 Total liquid fuel base wt.% 80.9 6.3 87.2

Claims (16)

1. The method of conversion of shale oil or a mixture of shale oils having a nitrogen content of at least 1 wt. %, characterized in that it contains the following stages:
a) the feedstock is processed in the hydroconversion section in the presence of hydrogen, said section comprising at least one fluidized bed reactor operating in a gaseous and liquid ascending mode and containing at least one supported catalyst;
b) the effluent obtained in stage a) is introduced, at least partially and often completely, into the fractionation zone, from which, through atmospheric distillation, a gaseous fraction, a ligroin fraction, a gas oil fraction and a heavier fraction than the gas oil fraction exit ;
c) said fraction of naphtha is treated, at least partially and often completely, in a hydrotreatment portion in the presence of hydrogen, said portion comprising at least one fixed bed reactor comprising at least one hydrotreatment catalyst; and
d) said gas oil fraction is treated, at least partially and often completely, in another part for hydrotreatment in the presence of hydrogen, said part comprising at least one fixed-bed reactor containing at least one hydrotreatment catalyst;
f) a fraction heavier than the gas oil fraction is subjected to liquid / liquid extraction to obtain a purified oil product and extract. 2. The method according to p. 1, in which shale oil or a mixture of shale oils have a nitrogen content of at least 2 wt. % 3. The method of claim 1, wherein the effluent obtained in step a) is fractionated by atmospheric distillation into a gaseous fraction having a boiling point of less than 50 ° C., a naphtha fraction boiling at a temperature of from about 50 ° C. to about 150 ° C, a gas oil fraction boiling at a temperature of from about 150 ° C to about 370 ° C, and a fraction that is heavier than the gas oil fraction, and which boils, as a rule, at a temperature above 370 ° C. 4. The method according to claim 1, wherein the solvent in the liquid / liquid extraction step e) is selected from the group consisting of furfural, N-methyl-2-pyrrolidone, sulfolane, dimethylformamide, dimethyl sulfoxide, phenol, or mixtures of these solvents in equal or different proportions. 5. The method of claim 1, wherein the liquid / liquid extraction step e) is carried out at a solvent / feed ratio of from 1/1 to 3/1, preferably from 1/1 to 1.8 / 1, at a temperature of ambient temperature to a temperature of 150 ° C and at a pressure from atmospheric pressure to a pressure of 2 MPa, preferably from atmospheric pressure to a pressure of 1 MPa. 6. The method according to claim 1, in which the parts for hydroprocessing with a fixed layer in stages c) and / or d) contain, upstream of the catalytic layers of the hydroprocessing, specific protective layers for arsenic compounds and silicon compounds. 7. The method according to claim 1, in which at least a portion of the refined oil obtained in the liquid / liquid extraction step e), after evaporation of the solvent, is introduced into the catalytic cracking part, denoted part f), in which it is processed under conditions conducive to obtaining a gaseous fraction, a gasoline fraction, a gas oil fraction and a heavy fraction. 8. The method of claim 7, wherein at least a portion of the heavy fraction obtained from the catalytic cracking step f) is recycled to the beginning of step f). 9. The method of claim 7, wherein at least a portion of the gas oil fraction obtained from the catalytic cracking step f) is recycled to the gas oil hydrotreatment step d). 10. The method of claim 1, wherein at least a portion of the extract obtained in the liquid / liquid extraction step e) is recycled to the beginning of step a). 11. The method according to p. 1, in which the hydroconversion stage a) is carried out at a temperature of from 300 ° C to 550 ° C, preferably from 400 ° C to 450 ° C, with a total pressure of 2 to 35 MPa, preferably from 10 to 20 MPa, with a mass hourly flow rate ((feed time / hour) / catalyst time) of 0.2 to 1.5 h ^-1 , preferably 0.3 to 1 h ^-1 and with a hydrogen / feed ratio of 50 to 5000 Nm ³ / m ³ preferably from 100 to 1000 Nm ³ / m ³ . 12. The method according to p. 1, in which the stage of hydroprocessing of the ligroin fraction c) is carried out at a temperature of from 280 ° C to 380 ° C, preferably from 300 ° C to 350 ° C, at a total pressure of 4 to 15 MPa, preferably from 10 up to 13 MPa, with a mass hourly flow rate ((feed time / hour) / catalyst time) equal to from 0.1 to 5 h ^-1 , preferably from 0.5 to 1 h ^-1 , and with a hydrogen / feed ratio from 100 to 5000 Nm ³ / m ³ , preferably from 200 to 1000 Nm ³ / m ³ . 13. The method according to p. 1, in which the stage of hydroprocessing of the gas oil fraction d) is carried out at a temperature of from 320 ° C to 450 ° C, preferably from 340 ° C to 400 ° C, with a total pressure of from 7 to 20 MPa, preferably from 10 up to 15 MPa, with a mass hourly flow rate ((feed time / hour) / catalyst time) equal to from 0.1 to 1 h ^-1 , preferably from 0.3 to 0.8 h ^-1 , and with a hydrogen / feed ratio from 100 to 5000 Nm ³ / m ³ , preferably from 200 to 1000 Nm ³ / m ³ . 14. The method according to p. 1, in which the catalyst in the hydroconversion stage a) contains a metal of group VIII selected from the group consisting of Ni and / or Co, optionally a metal of group VIB selected from the group consisting of Mo and / or W , on an amorphous substrate selected from the group consisting of alumina, silica, aluminosilicates, magnesium oxide, clays and mixtures of at least two of these minerals. 15. The method according to p. 1, in which the catalyst in the hydroprocessing stages c) and d) comprises a metal of group VIII selected from the group consisting of Ni and / or Co, optionally a metal of group VIB selected from the group consisting of Mo and / or W, on an amorphous substrate selected from the group consisting of alumina, silica, aluminosilicates, magnesium oxide, clays and mixtures of at least two of these minerals. 16. The method according to any one of the preceding paragraphs, in which shale oil or a mixture of shale oils is provided from hydrocarbon raw materials selected from the group consisting of oils derived from coal, oils derived from heavy resins and tar sand, vacuum distillates and direct distillation residues , vacuum distillates and unconverted residues obtained from the processing of fuel oil, oils deasphalted with solvents, light cyclic oils, heavy cyclic oils, gas oil fractions originating from ataliticheskogo cracking and having usually, a temperature range of boiling fractions of about 150 ° C to about 650 ° C, aromatic extracts obtained in the production of lubricating oils, or mixtures of such materials.

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