EP1278812B1 - Flexible method for producing oil bases with a zsm-48 zeolite - Google Patents

Abstract

The invention concerns an improved method for making very high quality oil bases optionally with simultaneous production of high quality middle distillates, comprising hydrotreating, hydrocracking preferably on Y or beta zeolite, topping steps. The effluent is subjected to catalytic dewaxing on ZSM-48 zeolite. The method then comprises steps of hydrofinishing to hydrogenate the aromatics, preferably on a catalyst comprising at least a noble metal of group VIII, chlorine and fluorine and steps of vacuum topping. The properties of the oils and middle distillates are enhanced (flow point, viscosity index, aromatic content) resulting even in production of medicinal oils.

Description

The present invention relates to an improved process for manufacturing base oils of very high quality that is to say having a high viscosity index (VI), a low aromatic content, good UV stability and a low pour point from petroleum fractions having a boiling point greater than 340 ° C, possibly with the simultaneous production of middle distillates (especially gas oils, kerosene) of very high quality, that is to say having a low aromatic content and a low pour point. The process according to the invention uses, in catalytic dewaxing, a catalyst based on ZSM-48.

Prior art

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

These lubricants are most often obtained by a succession of refining steps to improve the properties of a petroleum cut. In particular a treatment of heavy petroleum fractions with high levels of linear paraffins or little branched is necessary in order to obtain base oils of good quality and with the best possible yields, by an operation which aims to eliminate linear paraffins or very poorly connected, loads that 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 the oils lead to high pour points and thus to freezing phenomena for low temperature applications. In order to decrease the pour point values, these linear paraffins which are not or very slightly connected must be completely or partially eliminated.

This operation may be carried out by extraction with solvents such as toluene / methyl-ethyl ketone or methyl-isobutyl ketone mixtures, this being known as 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 byproducts, crude paraffins.

Another way is catalytic treatment in the presence or absence of hydrogen and, in view of their selectivity of form, zeolites are among the most used catalysts.
Zeolite catalysts such as ZSM-5, ZSM-11, ZSM-12, ZSM22, ZSM-23, ZSM-35 and ZSM-38 have been described for use in these processes.

International Patent Application WO 98/02503 describes a process for preparing an oil base comprising the dewaxing of a hydrocracked oil, using a dewaxing and hydroisomerization catalyst.

International Patent Application WO 95/10578 describes a process for reducing paraffins from a hydrocarbon feedstock to produce middle distillates. The method comprises contacting the feedstock with a hydrocracking catalyst comprising a carrier, a hydrogenating metal, and a zeolite, and contacting the effluent with a dewaxing catalyst having a crystalline molecular sieve.

French patent application FR 2,785,616 describes a process for producing base oils, and possibly middle distillates, comprising hydrotreatment, hydrocracking and atmospheric distillation.

Object of the invention

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

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

• (a) hydrotraitement réalisé à une température de 330-450°C, sous une pression de 5-25Mpa, avec une vitesse spatiale de 0,1-6h^-1, en présence d'hydrogène dans le rapport volumique hydrogène/hydrocarbure de 100-2000, et en présence d'un catalyseur amorphe comprenant au moins un métal du groupe VIII et au moins un métal du groupe VI B,
• (b) hydrocraquage, sans séparation intermédiaire de l'effluent obtenu à l'issue de l'hydrotraitement, l'hydrocraquage étant réalisé à une température de 340-430°C, sous une pression de 5-25Mpa, avec une vitesse spatiale de 0,1-5h-1, en présence d'hydrogène, et en présence d'un catalyseur contenant au moins une zéolithe et contenant également au moins un élément du groupe VIII et au moins un élément du groupe VI B.
• (c) distillation atmosphérique de l'effluent obtenu à l'issue de l'hydrocraquage pour séparer les gaz du liquide.
• (d) déparaffinage catalytique d'au moins une fraction liquide obtenue par distillation atmosphérique et qui contient des composés à point d'ébullition supérieur à 340°C, déparaffinage à une température de 200-500°C, sous une pression totale de 1-25Mpa, avec une vitesse volumique horaire de 0,05-50 h-1, avec 50-20001 d'hydrogène/l de charge, en présence d'un catalyseur comprenant une zéolithe choisie dans le groupe formé par les zéolithes ZSM-48, EU-2, EU-11 et ZBM-30,
• (e) l'effluent déparaffiné est directement soumis à un traitement d'hydrofinition réalisé à une température de 180-400°C, qui est inférieure à la température du déparaffinage catalytique d'au moins 20°C et d'au plus 200°C, sous une pression totale de 1-25Mpa, avec une vitesse volumique horaire de 0,05-100h^-1, en présence de 50-2000 litre d'hydrogène/litre de charge, et en présence d'un catalyseur amorphe pour l'hydrogénation des aromatiques, comprenant au moins un métal choisi dans le groupe des métaux du groupe VIII et des métaux du groupe VI B,
• (f) l'effluent issu du traitement d'hydrofinition est soumis à une étape de distillation comprenant une distillation atmosphérique et une distillation sous vide de façon à séparer au moins une fraction huile à un point d'ébullition supérieur à 340°C, et qui présente un point d'écoulement inférieur à -10°C, une teneur pondérale en composés aromatiques inférieure à 2 %, et un VI supérieur à 95, une viscosité à 100°C d'au moins 3cSt (soit 3mm²/s) et de façon à séparer éventuellement au moins une fraction distillat moyen présentant un point d'écoulement inférieur ou égal -20°C, une teneur en aromatiques d'au plus 2 % pds et une teneur en polyaromatiques d'au plus 1 % pds.

In particular and contrary to conventional process sequences or from the state of the prior art, this process is not limited in the quality of the oil products it provides; in particular, a judicious choice of the operating conditions makes it possible to obtain medicinal white oils (that is to say 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 feedstock. hydrocarbon containing at least 20% volume boiling above 340 ° C, the 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 Group VIII metal and at least one Group VI B metal,
• (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 5-25 MPa, 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 group VIII element and at least one group VI B element.
• (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 greater than 340 ° C, dewaxing at a temperature of 200-500 ° C, under a total pressure of 1 25Mpa, with an hourly space velocity of 0.05-50 h -1, with 50-2000 l of hydrogen / l of filler, in the presence of a catalyst comprising a zeolite selected from the group consisting of zeolites ZSM-48, EU-2, EU-11 and ZBM-30,
• (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 catalytic dewaxing temperature of at least 20 ° C and at most 200 ° C, under a total pressure of 1-25 MPa, with an hourly space velocity of 0.05-100h ^-1 , in the presence of 50-2000 liter of hydrogen / liter of feed, and in the presence of an amorphous catalyst for hydrogenation of aromatics, comprising at least one metal selected from the group of Group VIII metals and Group VI B metals,
• (f) the effluent from the hydrofinishing treatment is subjected to a distillation step comprising atmospheric distillation and 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 content by weight of aromatics of less than 2%, and a VI greater than 95, a viscosity at 100 ° C of at least 3cSt (ie 3mm ² / s) and so as to eventually separate at minus an average distillate fraction having a pour point less than or equal to -20 ° C, an aromatic content of not more than 2% by weight and a polyaromatic content of not more than 1% by weight.

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 middle distillates of high quality are obtained contains at least 20% boiling volume above 340 ° C.

Very varied loads can therefore be processed by the process.
The feedstock may be, for example, LCOs (light cycle oil), vacuum distillates obtained from the direct distillation of crude oil or from conversion units such as FCC, coker or visbreaking, or from extraction units. of aromatics, or derived from desulphurization or hydroconversion of RAT (atmospheric residues) and / or RSV (vacuum residues), or the charge may be a deasphalted oil, or any mixture of the aforementioned fillers. The list above is not exhaustive. In general, the fillers suitable for the objective oils have an initial boiling point above 340 ° C, and more preferably above 370 ° C.

The feedstock 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 provided, for example by at least one element of group VI B and at least one element of group VIII, at a temperature of between 330 and 450 ° C, preferably 360-420 ° C, at a pressure of 5 to 25 MPa, preferably lower at 20 MPa, the space velocity being between 0.1 and 6 h ^-1 , preferably 0.3-3 h ^-1 , and the quantity of hydrogen introduced is such that the volume ratio hydrogen / hydrocarbon is between 100 and 2000.

During the first step, the use of a hydrogenation-based catalyst over cracking, used under appropriate thermodynamic and kinetic conditions, allows a significant reduction in the content of condensed polycyclic aromatic hydrocarbons. In these circumstances, most of the Nitrogen and sulfur products from the feed are also processed. This operation makes it possible to eliminate two types of compounds known to be inhibitors of the zeolite catalyst which is used in the following process.

This first step makes it possible, by performing a precracking of the feedstock to be treated, to adjust the properties of the oil base at the outlet of this first step as a function of the quality of the oil base that is to be obtained at the outlet of the process. . Advantageously, this adjustment can be made by varying the nature and quality of the catalyst used in the first step and / or the temperature of this first step, so as to raise the viscosity number for the oil base, point fraction. boiling above 340 ° C, at the exit of this step. The viscosity index obtained, before dewaxing, is preferably between 80 and 150, and more preferably between 90 and 140, or even 90 and 130.
The support generally is based on (preferably consists essentially of) alumina or amorphous silica-alumina; it may also contain boron oxide, magnesia, zirconia, titanium oxide or a combination of these oxides. The hydro-dehydrogenating function is preferably filled with at least one metal or group VIII and VI metal compound 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 provides two advantages to hydrotreatment catalysts: an ease of preparation, especially when impregnating the nickel and molybdenum solutions, and a 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 alternatively NiMo and / or NiW catalysts on silica-alumina, or on silica-alumina-titanium oxide doped or not doped with at least one element included in the group of atoms formed by phosphorus, boron, fluorine and silicon .

The total concentration of metal oxides of 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 and 2. The concentration of phosphorus oxide P ₂ O ₅ will be less than 15% by weight and preferably 10% by weight.

The product obtained at the end of this first step is sent to a second catalyst in a second step 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 entirely 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 metal function hydrodehydrogenating.

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

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

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 Group VI B metals (for example molybdenum and / or tungsten) and / or preferably non-noble Group VIII metals (for example cobalt and / or nickel) of the classification. periodic elements. Preferably, this catalyst may also contain at least one promoter element deposited on the surface of the catalyst, element comprised 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, of 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 may advantageously contain phosphorus, the content of which, expressed as phosphorus oxide P ₂ O ₅ 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, silica, clay, alone or in mixtures.

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

The weight content of zeolite 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 metal elements such as, for example, rare earth metals, especially lanthanum and cerium, or noble or non-noble metals of group VIII, such as platinum, palladium or ruthenium, rhodium, iridium, iron and other metals such as manganese, zinc, magnesium.

A particularly advantageous HY acid zeolite is characterized by various specifications: an SiO ₂ / Al ₂ O ₃ molar ratio of between about 6 and 70 and preferably between about 12 and 50: a sodium content of less than 0.15% by weight on zeolite calcined at 1100 ° C; a crystalline parameter has elementary mesh of between 24.58 x 10 ^-10 m and 24.24 x 10 ^-10 m, and preferably between 24.38 x 10 ^-10 m and 24.26 x 10 ^-10 m; a sodium recovery CNa capacity, expressed in grams of Na per 100 grams of modified zeolite, neutralized and then calcined, greater than about 0.85; a specific surface area determined by the BET method of greater than about 400 m ² / g and preferably greater than 550 m ² / g, a water vapor adsorption capacity at 25 ° C for a partial pressure of 2.6 torr (ie 34.6 MPa), greater than about 6%, a porous distribution, determined by nitrogen physisorption, comprising between 5 and 45% and preferably between 5 and 40% of the total pore volume of the zeolite contained in pores with a diameter of between 20 x 10 ^-10 m and 80 x 10 ^-10 m, and between 5 and 45% and preferably between 5 and 40% of the total pore volume of the zeolite contained in pores with a diameter greater than 80 × 10 ^-10 m and generally less than 1000 × 10 ^-10 m, the remainder of the pore volume being contained in pores with a diameter of less than 20 x 10 ^-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, zeolite Y as previously defined and alumina.

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

These two steps (a) and (b) can be performed on both types of catalysts in (two or more) different reactors, 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 an atmospheric distillation (step c) so as to separate the gases (such as ammonia and hydrogen sulphide ( H ₂ S) formed, as well as other light gases that would be present, possibly hydrogen ...). At least one liquid fraction containing products whose boiling point is greater than 340 ° C. is obtained.

It is advantageously possible to distil at atmospheric pressure to obtain several fractions (gasoline, kerosene, gas oil for example), with a boiling point of not more than 340 ° C. and a fraction (called residue) with an initial boiling point greater than 340 ° C. C (and better than 370 ° C).

This fraction has a VI, before dewaxing, of between 95 and 165 and preferably of 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 distillation under vacuum.

In a variant of the process, the residue undergoes, before being catalytically dewaxed, an extraction of the aromatic compounds (constituting a step (c ') .This extraction is carried out by any known means, the most used solvents are furfurol and N-methylpyrrolidone.
The naphthenoaromatic compounds are thus extracted, and the raffinate obtained has a viscosity index greater 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 an objective of producing middle distillates, the cutting point is lowered, and instead of cutting at 340 ° C as before, it can for example include gas oils and possibly kerosene in the fraction containing compounds boiling above 340 ° C. For example, an initial boiling fraction 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. The usual operating conditions are employed.
The raffinate obtained has a viscosity index higher than the index of the incoming residue. This further increases the VI of the product obtained after the hydrofinition.

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

Generally, in this text middle distillates, the fraction (s) with initial boiling point of at least 150 ° C and final up to the residue, ie generally say up to 340 ° C, or preferably 370 ° C.
An advantage of this conversion process (hydrotreating and hydrocracking) described (thus using a zeolitic type catalyst) is that it generally makes it possible to manufacture lubricating oil bases 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 above 340 ° C unconverted, and preferably above 370 ° C, is a decreasing function of the conversion level obtained.
When this conversion level is high (above 70%), the viscosity of the resulting residue with an amorphous catalyst is such that it can not be used to produce the most viscous grades of lubricating oils (500 N and Bright Stock). This limitation disappears when using the zeolitic catalyst described above.

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 (V _100Z ) and at the same conversion, this ratio (V _100A / V _100Z ) 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 stage and the atmospheric distillation (c) is then subjected, at least in part, and preferably entirely, to a catalytic dewaxing step in the presence of hydrogen and a hydrodewaxing catalyst comprising an acid function and a hydro-dehydrogenating metal function and at least one matrix.

It should be noted that compounds boiling above 340 ° C are still subjected to catalytic dewaxing.

The acid function is provided by at least one zeolite selected from the group consisting of zeolites ZSm-48, EU-2, EU-11 and ZBM-30.

The use of said zeolites allows in particular the production of low pour point and high viscosity index products with good yields in the context of the process according to the invention.

The weight content of molecular sieves 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 examples and in a nonlimiting manner, alumina gels, aluminas, magnesia, amorphous silica-aluminas, and mixtures thereof. Techniques such as extrusion, pelletizing or coating may be used to perform the shaping operation.

The catalyst also comprises a hydro-dehydrogenating function ensured, for example, by at least one group VIII element and preferably at least one element comprised in the group consisting of platinum and palladium. The weight content of non-noble metal of 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 Group VIB metal (Mo and W preferred). If it is at least one noble metal of 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 noble metals of group VIII, platinum and / or palladium are preferably located on the matrix, defined as above.

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

The hydrocracking residue (that is to say the fraction with an initial boiling point greater than 340 ° C.) obtained in step (c) of the process according to the invention and which is to be treated in this stage ( d) of 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 weight a sulfur content of less than 50 ppm by weight, or better still 10 ppm by weight, a viscosity number of 35 to 165 (before dewaxing), preferably at least 110 and even more preferably less than 150, a content in aromatic compounds 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, the said fraction having an initial boiling point of less than or equal to 340 ° C and being catalytically dewaxed.

• la température de réaction est comprise entre 200 et 500°C et de préférence entre 250 et 470°C, avantageusement 270-430°C ;
• la pression est comprise entre 0,1 et 25 MPa (10⁶ Pa) et de préférence entre 1,0 et 20 MPa ;
• la vitesse volumique horaire (wh exprimée en volume de charge injectée par unité de volume de catalyseur et par heure) est comprise entre environ 0,05 et environ 50 et de préférence entre environ 0,1 et environ 20 h^-1 et de manière encore plus préférée entre 0,2 et 10 h^-1.

Elles sont choisies pour obtenir le point d'écoulement recherché.The operating conditions in which the hydrodeparaffinization 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, preferably 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 volume velocity (wh expressed as volume of feed injected per unit volume of catalyst per hour) is between about 0.05 and about 50 and preferably between about 0.1 and about 20 h ^-1 and still most 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 level of hydrogen used and expressed in liters of hydrogen per liter of filler is between 50 and about 2000 liters of hydrogen per liter of filler and preferably between 100 and 1500 liters of hydrogen per liter of filler.

It is known to those skilled in the art that the oil base pour point improvement, whether obtained by the solvent dewaxing (DPS) method or a catalytic hydrodewaxing (HDPC) process, causes a decrease in of the viscosity index (VI).

• la variation de VI lors de l'étape d'hydrodéparaffinage catalytique (HDPC) est de préférence supérieure ou égale à 0, pour un même point d'écoulement,
  ou
• lorsque on observe une diminution du VI lors de l'étape d'hydrodéparaffinage catalytique (HDPC) cette baisse est plus faible que celle qui peut être observée dans le cas d'un déparaffinage au solvant (DPS) pour obtenir le même point d'écoulement. Ainsi le rapport entre la variation de VI, de la base huile, lors de l'étape de déparaffinage catalytique, et la variation de VI, de la base huile, lors de l'étape de déparaffinage au solvant, ΔVI_HDPC/ ΔVI_DPS est strictement inférieur à 1 pour un même point d'écoulement.

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

• the variation of VI during the catalytic hydrodewaxing step (HDPC) is preferably greater than or equal to 0, for the same pour point,
  or
• when a decrease in VI is observed during the catalytic hydrodewaxing step (HDPC), this decrease is lower than that which can be observed in the case of solvent dewaxing (DPS) to obtain the same pour point . 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 _HDPC / ΔVI _DPS is strictly less than 1 for the same pour point.

Step (e): Hydrofinishing

The effluent leaving the catalytic hydrodewaxing step 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 boiling point below 340 ° C so as not to degrade the final yields including oils.

The catalyst used in this step comprises at least one Group VIII metal and / or at least one Group VIB element of the Periodic Table. The strong metal 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 an amorphous or crystalline oxide type support, such as, for example, aluminas, silicas, silica-aluminas.

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

The weight contents 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 wt.%, Advantageously 0.01 to 15 wt.%, Or even 0.01 to 10 wt.%, Preferably 0.01 to 5 wt.

Among the catalysts that can be used in this HDF step, and leading to excellent performance, and especially for obtaining medicinal oils, catalysts containing at least one noble metal of group VIII (platinum for example) and at least one halogen (chlorine and / or fluorine), the combination of chlorine and fluorine being preferred.

• la température de réaction est comprise entre 180 et 400°C et de préférence entre 210 et 350°C, avantageusement 230-320°C ;
• la pression est comprise entre 0,1 et 25 MPa (10⁶ Pa) et de préférence entre 1,0 et 20 MPa;
• la vitesse volumique horaire (wh exprimée en volume de charge injectée par unité de volume de catalyseur et par heure) est comprise entre environ 0,05 et environ 100 et de préférence entre environ 0,1 et environ 30 h^-1.

The operating conditions in 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 volume velocity (wh expressed as the volume of feed injected per unit volume of catalyst per hour) is from about 0.05 to about 100 and preferably from about 0.1 to about 30 h ^-1 .

The contact between the feedstock and the catalyst is carried out in the presence of hydrogen. The level of hydrogen used and expressed in liters of hydrogen per liter of filler is between 50 and about 2000 liters of hydrogen per liter of filler and preferably between 100 and 1500 liters of hydrogen per liter of filler.

One of the characteristics of the process according to the invention is that the temperature of the HDF step is lower than the temperature of the catalytic hydrodewaxing step (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, the purpose of which is to separate the conversion products with a boiling point below 340. ° C and preferably below 370 ° C, (and including in particular those formed during the catalytic hydrodewaxing step (HDPC)), the fraction which constitutes the oil base and whose initial boiling point is greater than 340 ° C and preferably greater than 370 ° C.

Moreover, this vacuum distillation section makes it possible to separate the different grades of oils.

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 greater than 95, preferably greater than 110 and even more preferably higher than 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 color ASTM is between 0 and 4 and preferably between 0, 5 and 2.5.

• a) couleur initiale ASTM D1500,
• b) couleur finale ASTM D1500,
• c) accroissement de la couleur,
• d) trouble,
• e) précipité.

The UV stability test, adapted from ASTM D925-55 and D1148-55, provides a quick method for comparing the stability of lubrication oils exposed to a source of ultraviolet rays. The test chamber consists of a metal enclosure equipped with a turntable which receives the oil samples. A bulb producing the same ultraviolet rays as those of sunlight and placed at the top of the test chamber is directed downwards on the samples. Included in the samples is a standard oil with known UV characteristics. The ASTM D1500 color of the samples is determined at t = 0 and after 45 hours 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) ASTM D1500 final color,
• c) increase in color,
• d) trouble,
• e) precipitated.

Another advantage of the process according to the invention is that it is possible to achieve very low aromatics contents, less than 2% by weight, preferably 1% by weight and better still less than 0.05% by weight, and even of go to the production of medicinal grade white oils with aromatic contents of less 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 interesting way, therefore, the process according to the invention also makes it possible to obtain medicinal white oils. Medical white oils are mineral oils obtained by advanced petroleum refining, their quality is subject to various regulations that aim to ensure their safety for pharmaceutical applications, they are devoid of toxicity and are characterized by their density and viscosity. White medicinal oils mainly comprise saturated hydrocarbons, they are chemically inert and their content of aromatic hydrocarbons is low. Particular attention is paid to aromatic compounds and in particular to 6 polycyclic aromatic hydrocarbons (PAHs for the abbreviation of polycyclic aromatic hydrocarbons) which are toxic and present at concentrations of one part per billion by weight of aromatic compounds in the form of polycyclic aromatic hydrocarbons. white oil. The control of the total aromatic content can be carried out 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, the white oils have aromatic contents of less than 0.01% by weight). These measurements are carried out with concentrations of 1 g of oil per liter, in a 1 cm tank. The white oils marketed differ in their viscosity but also in their original crude 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 chemical composition .
At present, oil cuts, whether from direct distillation of a crude oil followed by extraction of the aromatic compounds by a solvent, or from catalytic hydrorefining or hydrocracking processes, still contain significant amounts of aromatic compounds. In the current legislative framework of the majority of the industrialized countries, the so-called medicinal white oils must have an aromatic content lower than 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 UV adsorption specification which must be less than 1.60-275. nm on a 1 centimeter pure vessel product and a maximum specification of DMSO extraction product absorption which must be less than 0.1 for the US market (Food and Drug Administration, standard 1211145). This last test consists of specifically extracting polycyclic aromatic hydrocarbons using a polar solvent, often DMSO, and controlling their content in the extract by a UV absorption measurement in the domain 260-350 nm.

The average distillates obtained have improved pour points (less than or equal to -20 ° C.), low aromatics contents (at most 2% by weight), polyaromatic (di and more) contents of 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 reactors hence the possibility of working in series and use a single unit and thus generate 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 feed enters via the pipe (1) in a hydrotreatment zone (2) (which may be composed of one or more reactors, and comprise one or more catalytic beds of one or more catalysts) in which between hydrogen (for example via line (3)) and where the hydrotreating step (a) is carried out.

The hydrotreated feed is transferred via line (4) to the hydrocracking zone (5) (which may be composed of one or more reactors, and comprise one or more catalytic beds of one or more catalysts) where, in the presence of hydrogen is hydrocracking step (b).

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

A liquid fraction containing the compounds with a boiling point greater than 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 through a line (13) to perform 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 from driving (16). Hydrogen may 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 (process step f) comprising in addition to the flask (17) to separate the hydrogen by a line (18), an atmospheric distillation column (19) and a vacuum column ( 20) which treats the atmospheric distillation residue transferred via line (21), which has an initial boiling point of greater than 340 ° C.
Distillations are obtained as an oil fraction (line 22) and lower boiling fractions, such as gas oil (line 23), kerosene (line 24) gasoline (line 25); the light gases eliminated by the pipe (26) of the atmospheric column and the gases removed by the column (27) in vacuum distillation.

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

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

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

The recycling described later is entirely transferable.

The conversion set with 2 reactors without recycling of the effluent leaving the hydrocracker (5) is schematized here.

It is also possible to recycle a portion of this effluent to the hydrotreating step performed in zone (2) and / or to the hydrocracking step carried out in zone (5).

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

It is also common for the hydrotreating and hydrocracking zones to be in the same reactor. Therefore, the transfer of the hydrotreated effluent is done directly in the absence of pipe (4). Recycling the effluent is still possible either to the hydrotreatment 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 the line (11) and having 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 the zone (5) (comprising one or more reactors, one or more catalytic beds of one or more catalysts). This other hydrocracking zone may contain the same catalyst as zone (5) or another catalyst.

The resulting effluent is recycled to the atmospheric distillation step.
The remaining portion of the initial boiling point residue greater than 340 ° C is transferred to the catalytic dewaxing step.

In FIG. 3, these possible modalities of the conversion assembly have been schematized by taking the reference points common to FIG. 2 and which will not be redescribed.

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

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

The conversion assembly of FIG. 3 can thus substitute for the conversion assembly of FIG. 2, the hydrodewaxing, hydrofinishing and distillation train stages being unchanged. All the complementary possibilities (recycling H2 ..) are transposable.

In another variant of FIGS. 2 or 3, the residue leaving the pipe (11) is sent to the aromatics 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 flows into the catalytic dewaxing zone (12).
This variant (corresponding to step (c ') of the process) is shown in FIG. 4. The upstream and downstream treatments are those of the process such as for example illustrated in FIGS. 2 or 3.

• ◇ au moins une zone d'hydrotraitement (2) contenant au moins un catalyseur d'hydrotraitement et munie d'au moins une conduite (1) pour l'introduction de la charge et d'au moins une conduite (3) pour l'introduction de l'hydrogène,
• ◇ au moins une zone d'hydrocraquage (5) contenant au moins un catalyseur d'hydrocraquage, pour traiter l'effluent hydrotraité issu de la zone (2), l'effluent hydrocraqué sortant de la zone (5) par une conduite (6),
• ◇ au moins une colonne de distillation atmosphérique (9) pour traiter l'effluent hydrocraqué, et munie d'au moins une conduite (10) pour la sortie de la fraction gazeuse, d'au moins une conduite (11) pour la sortie d'une fraction liquide (résidu) contenant les composés à points d'ébullition supérieur à 340°C, d'au moins une conduite (28, 29 ou 30) pour la sortie d'au moins un distillat,
• ◇ au moins une unité d'extraction des composés aromatiques (35) pour traiter le résidu munie d'au moins une conduite (35) pour amener le solvant, d'au moins une conduite (36) pour sa sortie, et d'au moins une conduite (38) pour la sortie du raffinat,
• ◇ au moins une zone de déparaffinage catalytique (12) contenant au moins un catalyseur de déparaffinage, dans laquelle entre le raffinat , et par au moins une conduite (13) est admis de l'hydrogène, la zone (12) étant munie d'au moins une conduite (14) pour la sortie de l'effluent déparaffiné,
• ◇ au moins une zone d'hydrofinition (15) pour traiter l'effluent déparaffiné par un catalyseur d'hydrofinition, l'effluent sortant par au moins une conduite (16),
• ◇ au moins une zone de distillation comprenant au moins une colonne de distillation atmosphérique (19) et au moins une colonne de distillation sous vide (20), la colonne (19) étant munie d'au moins une conduite (26) pour la sortie des gaz légers, au moins une conduite (23, 24, ou 25) pour la sortie d'au moins un distillat, et au moins une conduite (21) pour récupérer un résidu, la colonne (20) comportant au moins une conduite (22) pour la sortie de la fraction huile et au moins une conduite (27) pour la sortie des autres composés.

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

• At least one hydrotreating zone (2) containing at least one hydrotreatment catalyst and provided with at least one pipe (1) for introducing the feedstock and at least one pipe (3) for introduction of hydrogen,
• At least one hydrocracking zone (5) containing at least one hydrocracking catalyst, for treating the hydrotreated effluent from zone (2), the hydrocracked effluent leaving the zone (5) via a pipe (6) )
• ◇ at least one atmospheric distillation column (9) for treating the hydrocracked effluent, and provided with at least one conduit (10) for the exit of the gaseous fraction, from at least one pipe (11) for the exit of a liquid fraction (residue) containing compounds with boiling points greater than 340 ° C, of at least one line (28, 29 or 30) for the outlet of at least one distillate,
• At least one aromatics extraction unit (35) for treating the residue provided with at least one line (35) to convey the solvent, at least one line (36) for its exit, and from at least one line (38) for the raffinate outlet,
• At least one catalytic dewaxing zone (12) containing at least one dewaxing catalyst, in which between the raffinate and at least one pipe (13) hydrogen is admitted, the zone (12) being provided with at least one pipe (14) for the outlet of the dewaxed effluent ,
• At least one hydrofinishing zone (15) for treating the dewaxed effluent with a hydrofinishing catalyst, the effluent exiting through at least one pipe (16),
• 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 the output of the oil fraction and at least one line (27) for the output of the other compounds.

In another embodiment, there is described an installation, in which the zones (2) and (3) are located in the same reactor provided with at least one pipe (1) for the entry of the charge, of at least one pipe (3) for the entry of hydrogen, and at least one pipe (6) for the outlet of the hydrocracked effluent, said plant further comprising at least one additional hydrocracking zone (32). ) provided with at least one pipe (11) for the admission of the residue from the atmospheric distillation column (9), and at least one pipe (33) for the outlet of the hydrocracked effluent, said pipe (33) ) opening into the pipe (6) for recycling said effluent, and further the installation comprises at least one pipe (34) located on the pipe (11) for transferring the residue to the extraction unit (35).

Claims (8)

1. Process for the production of oils and optionally high quality middle distillates from a hydrocarbon feedstock including at least 20% volume boil above 340°C, process that successively comprises the following stages:

   (a) Hydrotreatment carried out at a temperature of 330-450°C, under a pressure of 5-25 MPa, with a volumetric flow rate of 0.1-6 h^-1, in the presence of hydrogen in the hydrogen/hydrocarbon volumetric ratio of 100-2000, and in the presence of an amorphous catalyst that comprises at least one metal of group VIII and at least one metal of group VI B,

   (b) Hydrocracking, without intermediate separation of the effluent that is obtained at the end of the hydrotreatment, whereby the hydrocracking is carried out at a temperature of 340-430°C, under a pressure of 5-25 MPa, with a volumetric flow rate of 0.1-5 h^-1, in the presence of hydrogen, and in the presence of a catalyst that contains at least one zeolite and that also contains at least one element of group VIII and at least one element of group VI B,

   (c) atmospheric distillation of the effluent that is obtained at the end of the hydrocracking to separate the gases from the liquid, and to recover at least one liquid fraction that contains compounds with a boiling point of higher than 340°C,

   (d) whereby said fraction is treated directly by catalytic dewaxing at a temperature of 200-500°C, under a total pressure of 1-25 MPa, with an hourly volumetric flow rate of 0.05-50 h^-1, with 50-2000 1 of hydrogen/l of feedstock, in the presence of a catalyst that also comprises at least one element with a hydro-dehydrogenating function and at least one zeolite that is selected from the group that is formed by zeolites ZSM-48, EU-12, EU-11 and ZBM-30,

   (e) the dewaxed effluent is directly subjected to a hydrofinishing treatment that is carried out at a temperature of 180-400°C, which is lower than the catalytic dewaxing temperature by at least 20°C and at most 200°C, under a total pressure of 1-25 MPa, with an hourly volumetric flow rate of 0.05-100 h^-1, in the presence of 50-2000 liters of hydrogen/liter of feedstock, and in the presence of an amorphous catalyst for the hydrogenation of aromatic compounds, comprising at least one metal that is selected from the group of metals of group VIII and metals of group VI B,

   (f) the effluent that is obtained from the hydrofinishing treatment is subjected to a distillation stage that comprises an atmospheric distillation and a vacuum distillation so as to separate at least one oil fraction at a boiling point of higher than 340°C and that has a pour point of lower than -10°C, a content by weight of aromatic compounds of less than 2% and a VI of greater than 95, a viscosity at 100°C of at least 3cSt (or 3 mm²/s) and so as optionally to separate at least one middle distillate fraction that has a pour point of less than or equal to -20°C, a content of aromatic compounds of at most 2% by weight and a content of polyaromatic compounds of at most 1% by weight.
2. Process according to one of the preceding claims, wherein the hydrofinishing catalyst of stage (e) comprises an amorphous substrate, at least one noble element of group VIII, chlorine and fluorine.
3. Process according to one of the preceding claims, wherein hydrotreatment stages (a) and hydrocracking stages (b) are carried out in the same reactor.
4. Process according to one of the preceding claims, wherein hydrotreatment stages (a) and hydrocracking stages (b) are carried out in different reactors.
5. Process according to one of the preceding claims, wherein during stage (c) of atmospheric distillation, a residue with an initial boiling point of higher than 340°C is obtained that then undergoes the catalytic dewaxing of stage (d).
6. Process according to claim 5, wherein the hydrocracking residue is recycled at least in part in the hydrotreatment stage and/or in the hydrocracking stage.
7. Process according to claim 5, wherein at least a portion of the hydrocracking residue undergoes an additional hydrocracking stage that is different from stage (b), whereby the effluent that is obtained is recycled to atmospheric distillation stage (c), and the other portion of the residue is treated in dewaxing stage (d).
8. Process according to one of claims 5 to 7, wherein the residue that is obtained from the atmospheric distillation of stage (c) is subjected to an extraction of aromatic compounds (stage c'), and the raffinate that is obtained is catalytically dewaxed in stage (d).

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