EP1157084A1

EP1157084A1 - Adaptable method for producing medicinal oils and optionally middle distillates

Info

Publication number: EP1157084A1
Application number: EP99950885A
Authority: EP
Inventors: Eric Benazzi; Pierre Marion; Alain Billon; Christophe Gueret; Jean-Claude Hipeaux; Jean-Paul Gouzard
Original assignee: IFP Energies Nouvelles IFPEN
Current assignee: IFP Energies Nouvelles IFPEN
Priority date: 1998-11-06
Filing date: 1999-10-29
Publication date: 2001-11-28
Anticipated expiration: 2019-10-29
Also published as: DE69932186T2; CN1333808A; CN100457866C; BR9915120A; CZ303253B6; EP1157084B1; JP2002539277A; WO2000027950A1; ES2267296T3; JP4496647B2; BR9915120B1; KR100603225B1; CZ20011573A3; DE69932186D1; KR20010100987A

Abstract

The invention concerns an improved method for making high-quality basic oils optionally with simultaneous production of high-quality middle distillates, comprising hydrotreatment steps, preferably hydrocracking, on Y or beta zeolite, atmospheric distillation. The effluent (which is not vacuum-distilled) is subjected to catalytic dewaxing, preferably on NU-10, EU-1, EU-13 zeolite or ferrierite. The method then comprises steps of hydrofinishing to hydrogenate the aromatics, preferably on a catalyst comprising at least one noble metal of group VIII, chlorine and fluorine, and steps of atmospheric and vacuum distillation. The properties of the oils and the middle distillates are enhanced (flow point, viscosity index, aromatic content) resulting even in to medicinal oils.

Description

FLEXIBLE PROCESS FOR PRODUCING MEDICINAL OILS AND POSSIBLY MEDIUM DISTILLATES

The subject of the present invention is an improved process for manufacturing very high quality base oils, that is to say having a high viscosity index (VI), a low aromatic content, good UV stability and a low dots. '' flow, from petroleum fractions having a boiling point higher than 340 ° C, with possibly simultaneously the production of middle distillates (gas oils, kerosene in particular) of very high quality, that is to say having a low content in aromatics and a low pour point.

Prior art

High quality lubricants are of paramount importance for the proper functioning of modern machines, automobiles, and trucks.

These lubricants are most often obtained by a succession of refining steps allowing the improvement of the properties of an oil cut. In particular, a treatment of heavy petroleum fractions with high contents of linear or slightly branched paraffins is necessary in order to obtain good quality base oils and this with the best possible yields, by an operation which aims at eliminating linear or very paraffins. poorly connected, fillers which will then be used as base oils.

In fact, high molecular weight paraffins which are linear or very weakly branched and which are present in oils lead to high pour points and therefore to freezing phenomena for uses at low temperature. In order to decrease the pour point values, these linear paraffins with little or no branching must be entirely or partially removed.

This operation can be carried out by extraction with solvents such as toluene / methyl-ethyl ketone or methyl-isobutyl ketone mixtures, this is called methyl ethyl ketone (MEK) or methyl isobutyl ketone (MIBK) dewaxing. ). However, these techniques are expensive, not always easy to implement and lead to the formation of by-products, crude paraffins. Another means is the catalytic treatment in the presence or absence of hydrogen and, taking into account their shape selectivity, zeolites are among the least used catalysts.

Zeolite catalysts such as ZSM-5, ZSM-T1, ZSM-12, ZSM22, ZSM-23, ZSM-35 and ZSM-38 have been described for use in these methods.

Subject of the invention

The Applicant has focused its research efforts on the development of an improved process for manufacturing very high quality lubricating oils.

The present invention therefore relates to a series of processes for the joint production of very high quality base oils and very high quality middle distillates (gas oils). The oils obtained have a high viscosity index VI), a low aromatic content, low volatility, good UV stability and a low pour point, from petroleum fractions having a boiling point above 340 ° C. .

In particular, and unlike the usual process sequences or those originating from the state of the prior art, this process is not limited in the quality of the oil products that it makes it possible to obtain; in particular, a judicious choice of operating conditions makes it possible to obtain medicinal white oils (that is to say of excellent qualities). More specifically, the invention relates to a process for the production of high quality oils and possibly high quality middle distillates from a hydrocarbon feedstock of which at least 20% by volume boils above 340 ° C., process comprising successively the following stages:

(a) hydrotreatment carried out at a temperature of 330-450 ° C, under a pressure of 5-25Mpa, with a space velocity of 0.1-6h ^"1 , in the presence of hydrogen in the hydrogen / hydrocarbon volume ratio of 100 -2000, and in the presence of an amorphous catalyst comprising at least one metal from group VIII and at least one metal from group VI B,

(b) hydrocracking, without intermediate separation of the effluent obtained at the end of the hydrotreatment, the hydrocracking being carried out at a temperature of 340-430 ° C, under a pressure of 5-25Mpa, with a space velocity of 0.1-5h-1, in the presence of hydrogen, and in the presence of a catalyst containing at least one zeolite and also containing at least one element of group VIII and at least one element of group VI B. (c) atmospheric distillation of the effluent obtained after hydrocracking to separate the gases from the liquid.

(d) catalytic dewaxing of at least one liquid fraction obtained by atmospheric distillation and which contains compounds with a boiling point above 340 ° C., dewaxing at a temperature of 200-500 ° C., under a total pressure of 1 -25Mpa, with an hourly volume speed of 0.05-50 h-1, with 50-20001 of hydrogen / l of charge, in the presence of a catalyst also comprising at least one element with hydro-dehydrogenating function, and at at least one molecular sieve whose microporous system has at least one main type of channel with pore openings having 9 or 10 T atoms, T being chosen from the group formed by alternating Si / Ai, P, B, Ti, Fe, Ga with an equal number of oxygen atoms, the distance between two pore openings accessible to 9 or 10 T atoms being at most 0.75 mm, and said sieve having, in the n-decane test, a 2-methylnonane / 5 ratio -nethylnonane greater than 5, (e) the dewaxed effluent is directly subjected is a hydrofinishing treatment carried out at a temperature of 180-400 ° C, which is lower than the temperature of catalytic dewaxing by at least 20 ° C and at most 200 ° C, under a total pressure of 1- 25Mpa, with an hourly volume speed of

0.05-100h ^"1 , in the presence of 50-2000 liters of hydrogen / liter of feed, and in the presence of an amorphous catalyst for the hydrogenation of aromatics, comprising at least one metal chosen from the group of metals of group VIII and metals of group VI B,

(f) the effluent from the hydrofinishing treatment is subjected to a distillation step comprising an atmospheric distillation and a vacuum distillation so as to separate at least one oil fraction at a boiling point above 340 ° C, and which has a pour point of less than -10 ° C, a weight content of aromatic compounds of less than 2%, and an IV of more than 95, a viscosity of

100 ° C of at least 3cSt (i.e. 3mm ² / s) and so as to optionally separate at least one medium distillate fraction having a pour point less than or equal to -20 ° C, an aromatic content of at most 2 % w / w and a polyaromatic content of at most 1% w / w.

Detailed description of the invention

The method according to the invention comprises the following steps: Step (a): Hydrotreatment

The hydrocarbon feedstock from which the oils and possibly the high quality middle distillates are obtained contains at least 20% volume boiling above 340 ° C.

A wide variety of loads can therefore be treated by the process.

The feed can be, for example, LCOs (light cycle oil), vacuum distillates from the direct distillation of crude oil or from conversion units such as FCC, coker or viscoreduction, or from extraction units. aromatics, or from desulfurization or hydroconversion of RAT (atmospheric residues) and / or RSV (vacuum residues), or the filler can be a deasphalted oil, or any mixture of the charges mentioned above. The above list is not exhaustive. In general, the fillers suitable for the oils objective have an initial boiling point greater than 340 ° C, and better still greater than 370 ° C.

The feed is first subjected to a hydrotreatment, during which it is brought into contact, in the presence of hydrogen, with at least one catalyst comprising an amorphous support and at least one metal having a hydro-dehydrogenating function ensured for example. by at least one element from group VI B and at least one element from group VIII, at a temperature between 330 and 450 ° C, preferably 360-420 ° C, under a pressure between 5 and 25 Mpa, preferably lower at 20 MPa, the space speed being between 0.1 and 6 h ^"1 , preferably 0.3-3 h ^{" 1} , and the quantity of hydrogen introduced is such that the hydrogen / hydrocarbon volume ratio is between 100 and 2000.

During the first step, the use of a catalyst favoring hydrogenation over cracking, used under appropriate thermodynamic and kinetic conditions, allows a significant reduction in the content of condensed polycyclic aromatic hydrocarbons. Under these conditions, most of the nitrogen and sulfur products in the feed are also processed. This operation therefore makes it possible to eliminate two types of compounds which are known to be inhibitors of the zeolitic catalyst which is used in the rest of the process.

This first step allows, by pre-cracking the load to be treated, to adjust the properties of the oil base at the outlet of this first step depending the quality of the oil base that is to be obtained at the end of the process. Advantageously, this adjustment can be made by varying the nature and the quality of the catalyst used in the first step and / or the temperature of this first step, so as to raise the viscosity index for the oil base, fraction of a point. boiling above 340 ° C, at the end of this stage. The viscosity index obtained, before dewaxing, is preferably between 80 and 150, and better still between 90 and 140, or even 90 and 130.

The support generally is based on (preferably consists essentially) of alumina or of amorphous silica-alumina; it can also contain boron oxide, magnesia, zirconia, titanium oxide or a combination of these oxides. The hydro-dehydrogenating function is preferably fulfilled by at least one metal or compound of metal from groups VIII and VI preferably chosen from; molybdenum, tungsten, nickel and cobalt.

This catalyst may advantageously contain phosphorus; in fact, it is known in the prior art that the compound brings two advantages to hydrotreatment catalysts: ease of preparation during in particular the impregnation of nickel and molybdenum solutions, and better hydrogenation activity.

The preferred catalysts are the NiMo and / or NiW catalysts on alumina, also the NiMo and / or NiW catalysts on alumina doped with at least one element included in the group of atoms formed by phosphorus, boron, silicon and fluorine, or else the NiMo and / or NiW catalysts on silica-alumina, or on silica-alumina-titanium oxide doped or not with at least one element included in the group of atoms formed by phosphorus, boron, fluorine and silicon .

The total concentration of oxides of metals from groups VI and VIII is between 5 and 40% by weight and preferably between 7 and 30% and the weight ratio expressed as metal oxide between metal (or metals) of group VI on metal (or metals) of group VIII is preferably between 20 and 1.25 and even more preferably between 10 and 2. The concentration of phosphorus oxide P2O5 will be less than 15% by weight and preferably 10% by weight.

The product obtained at the end of this first stage is sent to a second catalyst in a second stage without intermediate separation of ammonia (NH ₃ ) and hydrogen sulfide (H ₂ S), nor distillation.

Step (b): Hydrocracking

The effluent from the first step (a) is completely introduced onto the catalyst of the second step (b) in the presence of hydrogen where it is hydrocracked in the presence of a bifunctional catalyst comprising a zeolitic acid function and a metallic function hydro-dehydrogenating.

During this stage, the polyaromatic and polynaphthenoaromatic compounds partially and / or totally hydrogenated during the first stage are hydrocracked on the acid sites to lead to the formation of paraffins. These paraffins in the presence of a bifunctional catalyst can undergo isomerization then optionally a hydrocracking to lead respectively to the formation of isoparaffins and lighter cracking products.

The conversion of polyaromatic compounds to several nuclei requires hydrogenation before their cracking.

The second stage catalyst comprises a zeolite, a support and a hydro-dehydrogenating function.

The hydro-dehydrogenating function is advantageously obtained by a combination of metals from groups VI B (for example molybdenum and / or tungsten) and / or metals from group VIII preferably non-noble (for example cobalt and / or nickel) of the classification of the elements. Preferably, this catalyst may also contain at least one promoter element deposited on the surface of the catalyst, element included in the group formed by phosphorus, boron and silicon and advantageously phosphorus.

The total concentration of metals of groups VI B and VIII, expressed as metal oxides relative to the support, is generally between 5 and 40% by weight, preferably between 7 and 30% by weight. The weight ratio (expressed as metal oxides) of group VIII metals to group VI B metals is preferably between 0.05 and 0.8; preferably between 0.13 and 0.5. This type of catalyst can advantageously contain phosphorus, the content of which, expressed as phosphorus oxide P2O5 relative to the support, will generally be less than 15% by weight, preferably less than 10% by weight.

The boron and silicon contents are less than 15% by weight and preferably less than 10% by weight (expressed as oxide).

The amorphous or poorly crystallized support is chosen from the group formed by alumina, silica, silica alumina, alumina-boron oxide, magnesia, silica-magnesia, zirconia, titanium oxide, l clay, alone or in mixtures.

The zeolite is advantageously chosen from the group formed by the zeolite Y (structural type FAU, faujasite) and the beta zeolite (structural type BEA) according to the nomenclature developed in "Atlas of zeolites structure types", WM Meier, DH Oison and Ch. Baerlocher, 4 ^{, h} revised Edition 1996, Elsevier.

The zeolite content by weight is between 2 and 80% and preferably between 3 and 50% relative to the final catalyst, and advantageously between 3-25%.

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

A particularly advantageous acidic zeolite HY is characterized by different specifications: a Siθ2 Al2θ3 molar ratio of between approximately 6 and 70 and preferably between approximately 12 and 50: a sodium content of less than 0.15% by weight determined on the calcined zeolite at 1100 ° C; a crystalline parameter has elementary mesh ranging between 24.58 x 10 ^" 10 m and 24.24 x 10 m and so

-10 -10 preferred between 24.38 x 10 m and 24.26 x 10 m; a CNa capacity for taking up sodium ions, expressed in grams of Na per 100 grams of modified zeolite, neutralized then calcined, greater than about 0.85; a specific surface determined by the B.E.T. greater than approximately 400 m ^ / g and preferably greater than 550 rn ^ / g, a water vapor adsorption capacity at 25 ° C for a partial pressure of 2.6 torrs (i.e. 34.6 MPa), greater than about 6%, a porous distribution, determined by physisorption of nitrogen, comprising between 5 and 45% and preferably between 5 and 40% of the total pore volume of the zeolite contained

-10 -10 in pores with a diameter between 20 x 10 m and 80 x 10 m, and between 5 and 45% and preferably between 5 and 40% of the total pore volume of the zeolite contained in

-10 pores with a diameter greater than 80 x 10 m and generally less than 1000 x

-10

10 m, the rest of the pore volume being contained in the pores of smaller diameter

-10 to 20 x 10 m.

A preferred catalyst essentially contains at least one group VI metal, and / or at least one non-noble group VIII metal, zeolite Y and alumina.

An even more preferred catalyst essentially contains nickel, molybdenum, a Y zeolite as defined above and alumina.

The operating conditions under which this second step (b) is carried out are important.

The pressure will be maintained between 5 and 25 MPa, advantageously between 5 and 20 MPa and preferably 7 to 15 MPa, the space speed will be between 0.1 h "1 and 5 h" 1 and preferably between 0.5 and 4 , 0 h "1.

The temperature is adjusted in the second step (b), so as to obtain the viscosity and the V.l. desired. It is between 340 and 430 ° C, and in general it is advantageously between 370 and 420 ° C.

These two stages (a) and (b) can be carried out on the two types of catalysts in (two or more) different reactors, or and preferably on at least two catalytic beds installed in the same reactor.

From the effluent leaving the hydrocracker, the hydrogen is separated, the effluent is then subjected directly to atmospheric distillation (step c) so as to separate the gases (such as ammonia and hydrogen sulfide ( H ₂ S) formed, as well as the other light gases which would be present, possibly hydrogen ...). At least one liquid fraction containing products with a boiling point above 340 ° C. is obtained.

It is advantageously possible to distil at atmospheric pressure to obtain several fractions (petrol, kerosene, diesel for example), with a boiling point of at most 340 ° C. and a fraction (called residue) with an initial boiling point of more than 340 °. C (and better above 370 ° C). This fraction has a VI, before dewaxing, between 95 and 165 and preferably at least 110.

According to the invention, this fraction (residue) will then be treated in the catalytic dewaxing step, that is to say without undergoing vacuum distillation.

In a variant of the process, the residue is subjected, before being catalytically dewaxed, to an extraction of the aromatic compounds (constituting a step (C).

This extraction is carried out by any known means, the most widely used solvents are ie furfurol and N-methylpyrolidone.

The naphthenoaromatic compounds are thus extracted, and the raffinate obtained has a higher viscosity index than that of the residue entering the extraction step. By this operation, an further increases the VI of the product obtained at the end of the hydrofinishing step.

In another embodiment more focused on the objective of producing middle distillates, the cutting point is lowered, and instead of cutting at 340 ° C. as previously, it is possible for example to include gas oils and possibly kerosene in the fraction containing compounds boiling above 340 ° C. For example, a fraction with an initial boiling point of at least 150 ° C. is obtained.

On the other hand, the residue can be extracted from the aromatic compounds before being catalytically dewaxed. This extraction is carried out by any known means, furfurol being most often used. Visual operating conditions are used.

The raffinate obtained has a viscosity index higher than the index of the incoming residue. The VI of the product obtained at the end of the hydrofinishing is thus further increased.

The fraction thus obtained containing the said compounds will be handled directly by catalytic dewaxing, the other fractions (150 ° C ^") being or not being treated separately in catalytic dewaxing, in this embodiment.

Generally speaking, in this text, middle distillates are called the initial boiling point fraction (s) of at least 150 ° C. and final going before the residue, that is to say generally say up to 340 ° C, or preferably 370 ° C.

An advantage of this conversion process (hydrotreating and hydrocracking) described (therefore using a zeolitic type catalyst) is that it generally makes it possible to manufacture bases of lubricating oils having a viscosity greater than that obtained by an amorphous catalyst at the same conversion. During the hydrocracking process, the viscosity at 100 ° C of the fraction of boiling point greater than 340 ° C which is not converted, and preferably greater than 370 ° C, is a decreasing function of the level of conversion obtained.

When this conversion level is high (above 70%), the viscosity of the residue obtained with an amorphous catalyst is such that it cannot be used to produce the most viscous grades of lubricating oils (500 N and Bright Stock). This limitation disappears when the zeolitic catalyst described above is used.

Thus, the ratio between the viscosity at 100 ° C of the hydrocracking residue 370 ° C +, obtained by a process using only non-zeolitic catalysts (V _100A ) and the viscosity at 100 ° C of the hydrocracking residue 370 ° C +, obtained by our process (iooz) and at the same conversion, this ratio (V _I OO _A / IOOZ) is strictly less than 1, preferably between 0.95 and 0.4.

Step (d): Catalytic hydrodewaxing (HDPC)

The fraction containing the compounds boiling above 340 ° C., as defined above, resulting from the second step and from atmospheric distillation (c) is then subjected, at least in part, and preferably in total, to a catalytic dewaxing step in the presence of hydrogen and a hydrodewaxing catalyst comprising an acid function and a metal hydrodehydrogenating function and at least one matrix.

Note that compounds boiling above 340 ° C are always subjected to catalytic dewaxing.

The acid function is ensured by at least one molecular sieve whose microporous system has at least one main type of channels whose openings are formed of rings which contain 10 or 9 T atoms. The T atoms are the tetrahedral atoms constituting the molecular sieve and can be at least one of the elements contained in the following set of atoms (Si, Al, P, B, Ti, Fe, Ga). In the constituent rings of the channel openings, the T atoms, defined above, alternate with an equal number of oxygen atoms. It is therefore equivalent to say that the openings are formed of rings which contain 10 or 9 oxygen atoms or formed of rings which contain 10 or 9 -T atoms.

The molecular sieve used in the composition of the hydrodewaxing catalyst may also include other types of channels but whose openings are formed of rings which contain less than 10 T atoms or oxygen atoms.

The molecular sieve entering into the composition of the catalyst also has a bridge width, distance between two pore openings, as defined above, which is at most 0.75 nm (1 nm = 10-9 m) preferably included between 0.50 nm and 0.75 nm, even more preferably between 0.52 nm and 0.73 nm.

The Applicant has indeed discovered that one of the determining factors for obtaining good catalytic performances in the third step (hydrodewaxing step) is the use of molecular sieves having a bridge width of at most 0.75 nm, preferably between 0.50 nm and 0.75 nm, preferably between 0.52 nm and 0.73 nm.

The bridge width measurement is carried out using a graphic design and molecular modeling tool such as Hyperchem or Biosym, which makes it possible to construct the surface of the molecular sieves in question and, taking into account the ionic rays of the elements present in the framework of the sieve, measure the bridge width.

The catalyst suitable for this process is characterized by a catalytic test called standard test for transformation of pure n-decane which is carried out under a partial pressure of 450 kPa of hydrogen and a partial pressure of nC ₁₀ of 1.2 kPa, ie a pressure total of 451.2 kPa in a fixed bed and with a constant flow of nC ₁₀ of 9.5 ml / h, a total flow of 3.6 l / h and a mass of catalyst of 0.2 g. The reaction is carried out in downward flow. The conversion rate is controlled by the temperature at which the reaction takes place. The catalyst subjected to said test consists of pure pelletized zeolite and 0.5% by weight of platinum.

The n-decane in the presence of the molecular sieve and of a hydro-dehydrogenating function will undergo hydroisomerization reactions which will produce products isomerized to 10 carbon atoms, and hydrocracking reactions leading to the formation of products containing less than 10 carbon atoms. Under these conditions, a molecular sieve used in the hydrodewaxing step according to the invention must have the physico-chemical characteristics described above and lead, for a yield of isomerized products of nC ₁₀ of the order of 5% by weight ( the conversion rate is regulated by temperature), at a 2-methylnonane / 5-methylnonane ratio greater than 5 and preferably greater than 7.

The use of molecular sieves thus selected, under the conditions described above, from the many molecular sieves already existing, allows in particular the production of products with low pour point and high viscosity index with good yields in the context of method according to the invention.

The molecular sieves which can enter into the composition of the catalytic hydrodewaxing catalyst are, by way of example, the following zeolites: Ferrierite, NU-10, EU-13, EU-1 and zeolites of the same structural type.

Preferably, the molecular sieves used in the composition of the hydrodewaxing catalyst are included in the assembly formed by ferrierite and EU-1 zeolite.

The content by weight of molecular sieve in the hydrodewaxing catalyst is between 1 and 90%, preferably between 5 and 90% and even more preferably between 10 and 85%. The matrices used to carry out the shaping of the catalyst are, by way of example and without limitation, alumina gels, aluminas, magnesia, amorphous silica-aluminas, and their mixtures. Techniques such as extrusion, pelletizing or coating, can be used to carry out the shaping operation.

The catalyst also includes a hydro-dehydrogenating function provided, for example, by at least one element of group VIII and preferably at least one element included in the assembly formed by platinum and palladium. The content by weight of non-noble metal from group VIII, relative to the final catalyst, is between 1 and 40%, preferably between 10 and 30%. In this case, the non-noble metal is often associated with at least one metal from group VIB (Mo and W preferred). If it is at least one noble metal from group VIII, the weight content, relative to the final catalyst, is less than 5%, preferably less than 3% and even more preferably less than 1.5 %.

In the case of the use of group VIII noble metals, platinum and / or palladium are preferably located on the matrix, defined as above.

The hydrodewaxing catalyst according to the invention can also contain from 0 to 20%, preferably from 0 to 10% by weight (expressed as oxides) phosphorus. The combination of Group VI B metal (s) and / or Group VIII metal (s) with phosphorus is particularly advantageous.

The hydrocracking residue (ie the fraction with an initial boiling point greater than 340 ° C.) which obtained in step (c) of the process according to the invention and which is to be treated in this step ( d) hydrodewaxing, has the following characteristics: it has an initial boiling point greater than 340 ° C and preferably greater than 370 ° C, a pour point of at least 15 ° C, a content of nitrogen less than 10 ppm by weight a sulfur content less than 50 ppm by weight or better than 10 ppm by weight, a viscosity index of 35 to 165 (before dewaxing), preferably at least equal to 110 and even more preferably less than 150, an aromatic content less than 10% by weight, a viscosity at 100 ° C greater than or equal to 3 cSt (mm ² / s).

These characteristics are also those of the residue which would be obtained by atmospheric distillation of a sample of a liquid fraction containing the compounds with a boiling point greater than 340 ° C., said fraction having an initial boiling point less than or equal to 340 ° C and being subjected to catalytic dewaxing.

The operating conditions under which the hydrodewaxing step of the process of the invention takes place are as follows:

- The reaction temperature is between 200 and 500 ° C and preferably between 250 and 470 ° C, advantageously 270-430 ° C;

- the pressure is between 0.1 and 25 MPa (10 ⁶ Pa) and preferably between 1.0 and 20 MPa; - the hourly space velocity (vvh expressed in volume of charge injected per unit volume of catalyst and per hour) is between approximately 0.05 and approximately 50 and preferably between approximately 0.1 and approximately 20 h ⁻¹ and so even more preferred between 0.2 and 10 h ^"1 .

They are chosen to obtain the desired pour point.

'The contact between the feed entering dewaxing and the catalyst is carried out in the presence of hydrogen. The rate of hydrogen used and expressed in liters of hydrogen per liter of charge is between 50 and approximately 2000 liters of hydrogen per liter of charge and preferably between 100 and 1500 liters of hydrogen per liter of charge.

A person skilled in the art knows that the improvement in the pour point of oil bases, whether obtained by the solvent dewaxing process (DPS) or by a catalytic hydrodewaxing process (HDPC), causes a drop. viscosity index (VI).

One of the characteristics of the process according to the invention is that:

the variation in VI during the catalytic hydrodewaxing stage (HDPC) is preferably greater than or equal to 0, for the same pour point, or

- when a decrease in the VI is observed during the catalytic hydrodewaxing stage (HDPC) this reduction is smaller than that which can be observed in the case of a dewaxing with solvent (DPS) to obtain the same point of flow. Thus the ratio between the variation of VI, of the oil base, during the catalytic dewaxing step, and the variation of VI, of the oil base, during the solvent dewaxing step, ΔVI _HD PC / ΔVI _DPS is strictly less than 1 for the same pour point.

Step (e): Hydrofinishing

The effluent at the outlet of the catalytic hydrodewaxing stage is, in its entirety and without intermediate distillation, sent to a hydrofinishing catalyst in the presence of hydrogen so as to carry out a thorough hydrogenation of the aromatic compounds which adversely affect the stability oils and distillates. However, the acidity of the catalyst must be low enough not to lead to the formation of cracking product with a boiling point below 340 ° C. so as not to degrade the final yields, in particular of oils. The catalyst used in this step comprises at least one metal from group VIII and / or at least one element from group VIB of the periodic table. The strong metallic functions: platinum and / or palladium, or nickel-tungsten, nickel-molybdenum combinations will advantageously be used to carry out a thorough hydrogenation of the aromatics.

These metals are deposited and dispersed on a support of amorphous or crystalline oxide type, such as, for example, aluminas, silicas, silica-aluminas.

The hydrofinishing catalyst (HDF) can also contain at least one element from group VII A of the periodic table. Preferably, these catalysts contain fluorine and / or chlorine.

The contents by weight of metals are between 10 and 30% in the case of non-noble metals and less than 2%, preferably between 0.1 and 1.5%, and even more preferably between 0.1 and 1.0% in the case of noble metals.

The total amount of halogen is between 0.02 and 30% by weight, advantageously 0.01 to 15%, or even 0.01 to 10%, preferably 0.01 to 5%.

Mention may be made, among the catalysts which can be used in this HDF step, and which lead to excellent performance, and in particular for obtaining medicinal oils, catalysts containing at least one noble metal from group VIII (platinum for example) and at least one halogen (chlorine and / or fluorine), the combination of chlorine and fluorine being preferred.

The operating conditions under which the hydrofinishing step of the process of the invention takes place are as follows:

- The reaction temperature is between 180 and 400 ° C and preferably between 210 and 350 ° C, preferably 230-320 ° C; the pressure is between 0.1 and 25 MPa (10 ⁶ Pa) and preferably between 1.0 and 20 MPa; the hourly space velocity (vvh expressed in volume of charge injected per unit volume of catalyst and per hour) is between approximately 0.05 and approximately 100 and preferably between approximately 0.1 and approximately 30 h -1.

Contact between the feed and the catalyst is carried out in the presence of hydrogen. The rate of hydrogen used and expressed in liters of hydrogen per liter of charge is between 50 and approximately 2000 liters of hydrogen per liter of charge and preferably between 100 and 1500 liters of hydrogen per liter of charge.

One of the characteristics of the process according to the invention is that the temperature of the HDF stage is lower than the temperature of the catalytic hydrodewaxing stage (HDPC). The difference T _HDPC -T _HDF is generally between 20 and 200, and preferably between 30 and 100 ° C.

The effluent leaving the HDF stage is sent to the distillation train, which incorporates atmospheric distillation and vacuum distillation, which aims to separate the conversion products from boiling point below 340 ° C and preferably less than 370 ° C, (and including in particular those formed during the catalytic hydrodewaxing stage (HDPC)), of the fraction which constitutes the oil base and whose initial boiling point is greater than 340 ° C and preferably higher than 370 ° C.

In addition, this vacuum distillation section allows the different grades of oils to be separated.

The base oils obtained according to this process have a pour point of less than -10 ° C, a weight content of aromatic compounds of less than 2%, a VI of more than 95, preferably more than 110 and even more preferably more at 120, a viscosity of at least 3.0 cSt at 100 ° C., an ASTM color of less than 1 and a UV stability such that the increase in the ASTM color is between 0 and 4 and preferably between 0, 5 and 2.5.

The UV stability test, adapted from ASTM D925-55 and D1148-55, provides a quick method for comparing the stability of lubricating oils exposed to a source of UV light. The test chamber consists of a metal enclosure provided with a turntable which receives the oil samples. A ampoule producing the same ultraviolet rays as those of sunlight and placed at the top of the test chamber is directed downwards on the samples. Among the samples is included a standard oil with known UN characteristics. The ASTM D1500 color of the samples is determined at t = 0 and then after 45 h of exposure at 55 ° C. The results are transcribed for the standard sample and the test samples as follows: a) initial color ASTM D1500, b) final color ASTM D1500, c) increase in color, d) haze, e) precipitate.

Another advantage of the process according to the invention is that it is possible to achieve very low aromatic contents, less than 2% by weight, preferably 1% by weight and better still less than 0.05% by weight) and even go as far as the production of white oils of medicinal quality having aromatic contents lower than 0.01% by weight. These oils have UV absorbance values at 275, 295 and 300 nanometers respectively less than 0.8, 0.4 and 0.3 (ASTM D2008 method) and a Saybolt color between 0 and 30.

In a particularly advantageous manner therefore, the method according to the invention also makes it possible to obtain medicinal white oils. White medical oils are mineral oils obtained by a refined refining of petroleum, their quality is subject to various regulations which aim to guarantee their harmlessness for pharmaceutical applications, they are devoid of toxicity and are characterized by their density and viscosity. Medicinal white oils mainly contain saturated hydrocarbons, they are chemically inert and their aromatic hydrocarbon content is low. Particular attention is paid to aromatic compounds and in particular to 6 polycyclic aromatic hydrocarbons (PAH for the Anglo-Saxon abbreviation of polycyclic aromatic hydrocarbons) which are toxic and present at concentrations of one part per billion by weight of aromatic compounds in l white oil. The total aromatics content can be checked by the ASTM D 2008 method, this UV adsorption test at 275, 292 and 300 nanometers makes it possible to control an absorbance less than 0.8, 0.4 and 0.3 respectively (that is to say that the white oils have aromatic contents of less than 0.01% by weight). These measurements are performed with concentrations of 1g of oil per liter, in a tank of 1 cm. The white oils sold are differentiated by their viscosity but also by their crude origin which can be paraffinic or naphthenic, these two parameters will induce differences both in the physicochemical properties of the white oils considered but also in their composition chemical.

Currently, the oil fractions, whether they come from the direct distillation of crude oil followed by an extraction of the aromatic compounds by a solvent, or whether they come from the catalytic hydrorefining or hydrocracking process, still contain significant quantities of aromatic compounds. Under the current legislative framework of the majority of industrialized countries, so-called medicinal white oils must have an aromatic content below a threshold imposed by the legislation of each country. The absence of these aromatic compounds in the oil cuts results in a Saybolt color specification which must be substantially at least 30 (+30), a maximum specification of UN adsorption. which must be less than 1.60 to 275 nm on a pure product in a tank of 1 cm and a maximum specification for absorption of the extraction products by DMSO which must be less than 0.1 for the American market (Food and Drug Administration, standard No. 1211145). This last test consists in specifically extracting polycyclic aromatic hydrocarbons using a polar solvent, often DMSO, and in controlling their content in the extract by measuring UV absorption in the 260-350 nm range.

The middle distillates obtained have improved pour points (less than or equal to -20 ° C.), low aromatic contents (at most 2% by weight), polyaromatic contents (di and more) less than 1% by weight and for gas oils, a cetane number greater than 50, and even greater than 52.

Another advantage of the process according to the invention is that the total pressure can be the same in all the reactors, hence the possibility of working in series and of using a single unit and therefore of generating cost savings.

The process is illustrated in FIGS. 1 and 2, FIG. 1 representing the treatment of the entire liquid fraction in hydrodewaxing and FIG. 2 that of a hydrocracking residue.

In FIG. 1, the charge enters via the line (1) into a hydrotreatment zone (2) (which can be composed of one or more reactors, and include one or more catalytic beds of one or more catalysts) in which enters hydrogen (for example by line (3)) and where step (a ) hydrotreatment.

The hydrotreated charge is transferred via line (4) into the hydrocracking zone (5) (which can be composed of one or more reactors, and include one or more catalytic beds of one or more catalysts) where is carried out, in the presence of hydrogen hydrocracking step (b).

The effluent from zone (5) is sent via a line (6) into a flask (7) for separation of the hydrogen which is extracted via a line (8), the effluent is then distilled at atmospheric pressure in the column (9) from which the gaseous fraction is extracted at the head by the pipe (10). Step (c) of the process is thus carried out.

A liquid fraction containing the compounds with a boiling point above 340 ° C. is obtained at the bottom of the column. This fraction is evacuated via line (11) to the catalytic dewaxing zone (12).

The catalytic dewaxing zone (12) (comprising one or more reactors, one or more catalytic beds of one or more catalysts) also receives hydrogen via a line (13) to carry out step (d) of the process.

The effluent leaving this zone via a pipe (14) is sent directly to the hydrofinishing zone (15) (comprising one or more reactors, one or more catalytic beds of one or more catalysts) from which it emerges by a line (16). Hydrogen can be added if necessary in the zone (15) where step (e) of the process is carried out.

The effluent obtained is separated in a distillation train (step f of the process) comprising, in addition to the flask (17) for separating the hydrogen by a line (18), an atmospheric distillation column (19) and a vacuum column ( 20) which processes the atmospheric distillation residue transferred via line (21), residue with an initial boiling point greater than 340 ° C.

It is obtained as products at the end of the distillations, an oil fraction (line 22) and lower boiling fractions, such as gas oil (line 23), kerosene (line 24) petrol (line 25); the light gases being eliminated by the pipe (26) from the atmospheric column and the gases being eliminated by the column (27) in vacuum distillation.

In order not to weigh down the figure, hydrogen recycling has not been shown, either at the level of the balloon (7) towards the hydrotreating and / or hydrocracking, and / or at the level of the balloon (17) towards the dewaxing and / or hydrofinishing.

We recognize in Figure 2 the marks of Figure 1. The difference is in the distillation of the effluent from the hydrocracking step (b) which leaves through the pipe (6). After separation of the hydrogen in the flask (7), it is separated by atmospheric distillation in a column (9) from the gases which are extracted via the line (10). The distillation is carried out so as to obtain a residue with an initial boiling point greater than 340 ° C. leaving via the line (11), and to obtain the diesel (line 28), kerosene (line 29) and gasoline (line 30) fractions. ).

Only the residue is treated in the dewaxing zone (12).

The recycling described later is completely transposable.

We have schematized here the conversion assembly with 2 reactors without recycling of the effluent leaving the hydrocracker (5).

It is also possible to recycle part of this effluent to the hydrotreatment stage carried out in zone (2) and / or to the hydrocracking stage carried out in zone (5).

The operator will adapt the recycling rate to its "products" objective to encourage obtaining oils or rather that of middle distillates.

It is also frequent that the hydrotreating and hydrocracking zones are in the same reactor. Consequently, the transfer of the hydrotreated effluent takes place directly in the absence of a pipe (4). Effluent recycling is always possible either to the hydrotreating zone (upstream of a catalyst bed) or to the hydrocracking zone. In another embodiment of this conversion step (hydrocracking in two steps), the residue leaving via line (11) and which has an initial boiling point greater than 340 ° C. (as shown in FIG. 2) is sent , at least in part, in an additional hydrocracking zone (32), different from zone (5) (comprising one or more reactors, one or more catalytic beds of one or more catalysts). This other hydrocracking zone can contain the same catalyst as zone (5) or another catalyst.

The resulting effluent is recycled to the atmospheric distillation stage.

The other part of the residue with an initial boiling point above 340 ° C. is transferred to the catalytic dewaxing stage.

In Figure 3, we have schematized these possible modalities of the conversion assembly by taking the common reference points with Figure 2 and which will not be described again.

The residue leaving the column (9) via the pipe (11) is sent to the other hydrocracking zone (32), from which an effluent emerges in a pipe (33) which is recycled in the column (9) . By a pipe (34) connected to the pipe (11) leaves the residue which is sent to ia dewaxing zone (12).

FIG. 3 also shows the production in the same reactor (31) of the hydrotreating and (5) hydrocracking zones (2), but separate zones are quite possible in combination with the additional zone (32) d 'hydrocracking.

The conversion assembly of FIG. 3 can thus replace the conversion assembly of FIG. 2, the steps hydrodewaxing, hydrofinishing, and the distillation train being unchanged. All the additional possibilities (recycling H2 ..) can be transposed.

In another variant of FIGS. 2 or 3, the residue leaving the pipe (11) is sent to the aromatic compound extraction unit (35) provided with a pipe (36) for the entry of the solvent, d a line (37) for the exit of the solvent and a line (38) through which the raffinate leaves which is sent to the catalytic dewaxing zone (12).

This variant (corresponding to step (c ') of the method) is shown in FIG. 4. The upstream and downstream treatments are those of the method such as for example illustrated in FIGS. 2 or 3.

Thus, the invention also relates to an installation for the production of high quality oils and possibly high quality middle distillates, comprising:

0 at least one hydrotreatment zone (2) containing at least one hydrotreatment catalyst and provided with at least one line (1) for the introduction of the charge and at least one line (3) for the introduction of hydrogen,

0 at least one hydrocracking zone (5) containing at least one hydrocracking catalyst, for treating the hydrotreated effluent coming from the zone (2), the hydrocracked effluent leaving the zone (5) via a pipe (6 ),

0 at least one atmospheric distillation column (9) for treating the hydrocracked effluent, and provided with at least one pipe (10) for the outlet of the gaseous fraction, at least one pipe (1 1) for the outlet a liquid fraction (residue) containing the compounds with boiling points above 340 ° C, at least one line (28, 29 or 30) for the outlet of at least one distillate,

0 at least one aromatic compound extraction unit (35) for treating the residue provided with at least one line (35) for supplying the solvent, at least one line (36) for its outlet, and at least minus a pipe (38) for leaving the raffinate,

0 at least one catalytic dewaxing zone (12) containing at least one dewaxing catalyst, into which the raffinate, and through at least one line (13), is admitted with hydrogen, the zone (12) being provided with at least one line (14) for the outlet of the dewaxed effluent, 0 at least one hydrofinishing zone (15) for treating the dewaxed effluent with a hydrofinishing catalyst, the effluent leaving through at least one line ( 16),

0 at least one distillation zone comprising at least one atmospheric distillation column (19) and at least one vacuum distillation column (20), the column (19) being provided with at least one pipe (26) for the outlet light gases, at least one line (23, 24, or 25) for the outlet of at least one distillate, and at least one line (21) for recovering a residue, the column (20) comprising at least one line ( 22) for ia outlet of the oil fraction and at least one line (27) for the outlet of the other compounds.

In another embodiment, the invention therefore also relates to an installation, in which the zones (2) and (3) are located in the same reactor provided with at least a line (1) for the entry of the charge, at least one line (3) for the entry of hydrogen, and at least one line (6) for the exit of the hydrocracked effluent, said installation further comprising at least one additional hydrocracking zone (32) provided with at least one pipe (11) for admitting the residue from the atmospheric distillation column (9), and at least one pipe (33 ) for the outlet of the thus hydrocracked effluent, said pipe (33) opening into the pipe (6) to recycle said effluent, and furthermore the installation comprises at least one pipe (34) located on the pipe (11) for transfer the residue to the extraction unit (35).

Example 1:

The hydrocracking residue is obtained by hydrocracking a vacuum distillate whose composition is given in Table 1.

In a reactor containing an amorphous catalyst bed (15% Mo03, 5% NiO, 80% alumina), the charge described in Table 1 and hydrogen are introduced under a pressure of 14 MPa and in a volumetric ratio H ₂ / HC = 1000Ni / Ni. The space speed is then 0.75h-1 on the amorphous catalyst. The reaction temperature is 380 ° C.

A catalyst 12% MoO3, 4% NiO, 20% zeolite Y on alumina is charged to a second reactor located after this first reactor. The product from the first reactor is introduced into the second reactor. The pressure is 14 MPa and the product circulates at a spatial speed of 1.5 hr ^-1 . The effluent is recovered and then distilled under vacuum. The characteristics of the residue 375 ° C ⁺ are given in Table 1.

Example 2

The residue 375 ° C ⁺ obtained in Example 1 is then introduced into a reactor containing a bed of hydrodewaxing catalyst (0.5% Pt, 80% ferrierite, the remainder being Al ₂ 0 ₃ ) and hydrogen under a pressure of 14 MPa and in a volumetric ratio H ₂ / HC = 1000Ni / Ni. The space speed is then 1h-1 on this catalyst. The reaction temperature is 315 ° C.

Is loaded into a second reactor located after this first reactor, a catalyst containing 1% by weight of pt, 1% by weight of Cl on alumina. The product from the first reactor is introduced into the second reactor which is maintained at a temperature of

220 ° C. The pressure is 14 MPa and the product circulates at a space speed of 0.5h ^" ¹ . The effluent is collected and then distilled under vacuum. The characteristics of the residue 375 ° C ⁺ are reported in Table 1.

The test of carbonisable materials on the dewaxed and hydrofinished residue produced in Example 2 obeys the standard in force.

Furthermore, the UV absorption at 275 nm on pure product, in a 1 cm tank, is 1.2, therefore less than the standard.

Consequently, the dewaxed and hydrofine residue produced in Example 2 constitutes a medicinal oil.

Table 1

Claims

Process for the production of medicinal oils and possibly high-quality middle distillates from a hydrocarbon feedstock of which at least 20% by volume boils above 340 ° C., the medicinal oils having a Saybolt color of substantially at least 30 , a maximum adsorption value of UN. less than 1.60 to 275 nm on a pure product in a tank of 1 cm and a maximum value of absorption of the extraction products by DMSO less than 0.1, a process comprising successively the following steps:

(a) hydrotreatment carried out at a temperature of 330-450 ° C, under a pressure of 5-25Mpa, with a space velocity of 0.1-6h ^"1 , in the presence of hydrogen in the hydrogen / hydrocarbon volume ratio of 100 -2000, and in the presence of an amorphous catalyst comprising at least one metal from the group

VIII and at least one metal from group VI B,

(b) hydrocracking, without intermediate separation of the effluent obtained at the end of the hydrotreatment, the hydrocracking being carried out at a temperature of 340-430 ° C, under a pressure of 5-25Mpa, with a spatial speed of 0.1-5h ^"1 , in the presence of hydrogen, and in the presence of a catalyst containing at least one zeolite and also containing at least one element of group VIII and at least one element of group VI B,

(c) atmospheric distillation of the effluent obtained at the end of hydrocracking to separate the gases from the liquid, (d) catalytic dewaxing of at least one liquid fraction obtained by atmospheric distillation and which contains point compounds boiling above 340 ° C, dewaxing at a temperature of 200-500 ° C, under a total pressure of 1-25Mpa, with an hourly volume speed of 0.05-50 hr ^"1 , with 50-20001 of hydrogen / l of feedstock, in the presence of a catalyst also comprising at least one element with a hydro-dehydrogenating function, and at least one molecular sieve whose microporous system has at least one main type of channels with pore openings having 9 or 10 T atoms , T being chosen from the group formed by Si / Ai, P, B, Ti, Fe, Ga, alternating with an equal number of oxygen atoms, the distance between two pore openings accessible to 9 or 10 T atoms being at most 0.75 mm, and said sieve presenting in test n- decane a 2-methylnonane / 5-nethylnonane ratio greater than 5, (e) the dewaxed effluent is directly subjected to a hydrofinishing treatment carried out at a temperature of 180-400 ° C, which is lower than the temperature of the catalytic dewaxing by at least 20 ° C and at most 200 ° C, under a total pressure of 1-25Mpa, with an hourly volume speed of 0.05-100h ^"1 , in the presence of 50-2000 liter of hydrogen / liter of charge, and in the presence of an amorphous catalyst for l hydrogenation of aromatics, comprising at least one metal chosen from the group of metals from group VIII and metals from group VI B,

(f) the effluent from the hydrofinishing treatment is subjected to a distillation step comprising an atmospheric distillation and a vacuum distillation so as to separate at least one oil fraction at a boiling point above 340 ° C, and which has a pour point of less than -10 ° C, a weight content of aromatic compounds of less than 2%, and an IV of more than 95, a viscosity at 100 ° C of at least 3cSt (i.e. 3mm ² / s) and so as to optionally separate at least one middle distillate fraction having a pour point of less than or equal to -20 ° C., an aromatic content of at most 2% by weight and a polyaromatic content of at most 1% by weight.

2. The method of claim 1 wherein the molecular sieve of the dewaxing step (d) is selected from the group consisting of ferrierite zeolites, NU-10, EU-1, EU-13.

3. Method according to one of the preceding claims, in which for the dewaxing catalyst of step (d), the element with a hydro-dehydrogenating function is chosen from the group formed by the elements of group VIII and the elements of the group VI B, said catalyst further containing phosphorus.

4. Method according to one of the preceding claims, wherein the hydrofinishing catalyst of step (e) comprises an amorphous support, at least one noble element of group VIII, chlorine and fluorine.

5. Method according to one of the preceding claims, in which the steps (a) of hydrotreating and (b) of hydrocracking are carried out in the same reactor.

6. Method according to one of claims 1 to 4 wherein the steps (a) of hydrotreating and (b) of hydrocracking are carried out in different reactors.

7. Method according to one of the preceding claims, wherein during step (c) of atmospheric distillation, there is obtained a residue with an initial boiling point greater than 340 ° C and which then undergoes catalytic dewaxing of l 'step (d).

8. The method of claim 7 wherein the hydrocracking residue is recycled at least in part in the hydrotreating step and / or in the hydrocracking step.

9. The method of claim 7 wherein at least part of the hydrocracking residue undergoes an additional hydrocracking step different from step (b), the effluent obtained being recycled to step (c) of atmospheric distillation , the other part of the residue being treated in step (d) of dewaxing.

10. Method according to one of claims 7 to 9 wherein the residue from the atmospheric distillation of step (c) is subjected to an extraction of aromatic compounds (step c '), and the raffinate obtained is catalytically dewaxed in step (d).

11. Method according to one of the preceding claims for the production of white oils having aromatic contents of less than 0.01% by weight.

12. Installation for the production of high quality oils and possibly high quality middle distillates, comprising:

0 at least one hydrotreatment zone (2) containing at least one hydrotreatment catalyst and provided with at least one line (1) for the introduction of the charge and at least one line (3) for the introduction of hydrogen, 0 at least one hydrocracking zone (5) containing at least one hydrocracking catalyst, to treat the hydrotreated effluent from zone (2), the hydrocracked effluent leaving zone (5 ) by a pipe (6), 0 at least one atmospheric distillation column (9) for treating the hydrocracked effluent, and provided with at least one pipe (10) for the outlet of the fraction gas, at least one line (11) for the outlet of a liquid fraction (residue) containing the compounds with boiling points above 340 ° C, and at least one line (28, 29 or 30) for the output of at least one distillate, 0 at least one aromatic compound extraction unit (35) for treating the residue provided with at least one line (35) for supplying the solvent, with at least one line ( 36) for its outlet, and at least one pipe (38) for the outlet of the raffinate,

0 at least one catalytic dewaxing zone (12) containing at least one dewaxing catalyst, into which the raffinate, and through at least one line (13), is admitted with hydrogen, the zone (12) being provided with at least one line (14) for the outlet of the dewaxed effluent,

0 at least one hydrofinishing zone (15) for treating the dewaxed effluent with a hydrofinishing catalyst, the effluent leaving by at least one line (16), 0 at least one distillation zone comprising at least one column of atmospheric distillation (19) and at least one vacuum distillation column

(20), the column (19) being provided with at least one pipe (26) for the exit of light gases, at least one pipe (23, 24, or 25) for the exit of at least one distillate, and at least one line (21) for recovering a residue, the column (20) comprising at least one line (22) for the outlet of the oil fraction and at least one line (27) for the outlet of the other compounds.

13. Installation according to claim 12, in which the zones (2) and (3) are located in the same reactor provided with at least one line (1) for the entry of the load, at least one line ( 3) for the entry of hydrogen, and at least one line (6) for the exit of the hydrocracked effluent, said installation further comprising at least one additional hydrocracking zone (32) provided with at least one line (11) for the admission of the residue from the atmospheric distillation column (9), and at least one line (33) for the outlet of the thus hydrocracked effluent, said line (33) opening into the line (6 ) to recycle said effluent, and in addition the installation comprises at least one pipe (34) located on the pipe (11) for transferring the residue to the extraction unit (35).