EP1307526A1

EP1307526A1 - Flexible method for producing oil bases and distillates from feedstock containing heteroatoms

Info

Publication number: EP1307526A1
Application number: EP01958156A
Authority: EP
Inventors: Eric Benazzi; Christophe Gueret; Pierre Marion; Alain Billon
Original assignee: IFP Energies Nouvelles IFPEN
Current assignee: IFP Energies Nouvelles IFPEN
Priority date: 2000-07-26
Filing date: 2001-07-23
Publication date: 2003-05-07
Anticipated expiration: 2021-07-23
Also published as: DE60141519D1; EP1307526B1; KR20030020398A; US20040004021A1; JP2004504479A; BR0112684B1; CZ304523B6; ES2340253T3; FR2812301B1; BR0112684A; NO20030395L; US7250107B2; CZ2003463A3; FR2812301A1; KR100813745B1; NO20030395D0; WO2002008363A1

Abstract

The invention concerns an improved method for making oil bases and in particular of very high quality oils that is having a high viscosity index (VI), low aromatic content, good UV stability, and low flow point, from fractions having an initial boiling point higher than 340 °C, while optionally simultaneously producing very high quality middle distillates ( in particular diesel oil, kerosene), that is having low aromatic content and a low flow point. More precisely, the invention concerns a flexible method for producing oil base and middle distillates from a feedstock containing heteroatoms, that is containing more than 200 ppm by weight of nitrogen and more than 500 ppm by weight of sulphur. The method comprises at least a hydrorefining step, at least a zeolite catalyst dewaxing step, at least a hydrofinishing step.

Description

FLEXIBLE PROCESS FOR PRODUCING OIL BASES AND MEDIUM DISTILLATES FROM FILLERS CONTAINING

HETEROATOMS

The present invention describes 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 pour point. , from petroleum fractions having an initial boiling point above 340 ° C, with possibly simultaneously the production of very high quality middle distillates (gas oils, kerosene), that is to say having a low content of aromatic and a low pour point.

More specifically, the invention relates to a flexible process for the basic production of oils and middle distillates from a feed containing heteroatoms (eg N, S, O ... and preferably free of metals), that is to say containing more than 200 ppm by weight of nitrogen and more than 500 ppm by weight of sulfur. The process comprises at least one hydrorefining step, at least one catalytic dewaxing step on zeolite and at least one hydrofinishing step.

Prior art

The patent US-5, 976, 354 describes a process for the production of oils comprising these 3 stages.

The first step carries out the deazotation and the desulfurization of the feed in the presence of a catalyst based on a non-noble metal from groups VIII and / or VI B and an alumina or silica-alumina support, the preferred catalysts being prepared by impregnation of the support preformed. The effluent obtained, after stripping of the gases, is treated in the catalytic dewaxing step on a catalyst based on zeolite ZSM-5, ZSM-35 or molecular sieve type SAPO, the catalyst also containing at least one hydrogenating catalytic metal. The process ends with a hydrofinishing step to achieve the saturation of the aromatics using a catalyst comprising Pt and Pd oxides on alumina, or using a preferred catalyst based on Y zeolite. In a communication from DV Law at the 7 ^th Refinery Technology Meeting in Bombay, December 6-8, 1993, a process for the production of oils and middle distillates is described.

It comprises a first hydrocracking step carrying out a deactivation, a cracking of the components with low VI (viscosity index) and a rearrangement (saturation of aromatics, opening of naphthenic cycle) producing compounds with high VI. This step is carried out in the presence of a cogel-type catalyst having a high uniform dispersion as a hydrogenating element and a unique distribution of pore sizes. Such catalysts are said to be clearly superior to the catalysts obtained by impregnation of the support. An example is the ICR106 catalyst. The effluent obtained is distilled, the naphtha, jet fuel, diesel cuts are separated as well as the gases, and the remaining fractions (neutral oils and bright stock) are treated by catalytic dewaxing.

In this step, isomerization of the n-paraffins is carried out on an ICR404 catalyst. The process also ends with a hydrofinishing step.

No other information is given on the implementation of the dewaxing and hydrofinishing stages. It is indicated that the VI of the final oil increases according to the wax content of the filler and according to the severity of the hydrocracking.

Subject of the invention

The Applicant has focused its research efforts on the development of an improved process for manufacturing lubricating oils and in particular very high quality 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), from petroleum fractions having an initial boiling point greater than 340 ° C. The oils obtained have a high viscosity index VI, a low aromatic content, low volatility, good UV stability and a low point. flow.

The present application proposes an alternative process to the processes of the prior art which, by a particular choice of catalysts and conditions, makes it possible to produce oils and middle distillates of good quality, under mild conditions and with long cycle times. .

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 oils and middle distillates from a charge containing more than 200 ppm by weight of nitrogen and more than 500 ppm by weight of sulfur, and of which at least 20% by volume boils above 340 ° C, comprising the following stages:

(a) hydrorefining of the charge, carried out at a temperature of 330 ° -450 ° C, under a pressure of 5-25Mpa, with a space speed of 0.1-1 Oh ^'1 , in the presence of hydrogen in the ratio hydrogen / hydrocarbon volume of 100-2000, and in the presence of an amorphous catalyst comprising a support and at least one non-noble metal from group VIII, at least one metal from group VI B, and at least one doping element chosen from the group formed by phosphorus, boron and silicon, (b) from the effluent obtained in step (a) separation of at least the gases and the compounds with a boiling point below 150 ° C,

(c) catalytic dewaxing of at least part of the effluent at the end of step (b) and which contains compounds with a boiling point higher than

340 ° C, carried out at a temperature of 200-500 ° C, under a total pressure of 1 -25MPa, with an hourly volume speed of 0.05-50h ^"1 , with 50-

2000I of hydrogen / l of charge, and in the presence of a catalyst comprising at least one hydro-dehydrogenating element and at least one molecular sieve,

(d) hydrofinishing at least part of the effluent from step (c) carried out at a temperature of 180-400 ° C, under a pressure of 1-25MPa, with an hourly volume speed of 0.05 -100h ^"1 , in the presence of 50-20001 of hydrogen / l of charge, and in the presence of an amorphous catalyst for the hydrogenation of aromatics comprising at least one hydro-dehydrogenating metal and at least one halogen.

(E) separation of the effluent obtained in step (d) to obtain at least one oil fraction.

Generally 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 with an initial boiling point above 340 ° C., which preferably has a pour point of less than -10 ° C, a weight content of aromatic compounds of less than 2%, and a VI 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 medium distillate fraction preferably, having a pour point less than or equal to -10 ° C and preferably -20 ° C, an aromatic content of at most 2% by weight and a polyaromatic content of at most 1% by weight.

Detailed description of the invention

The method according to the invention comprises the following steps:

Step (a): Hydrorefining

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, vacuum distillates from the distillation. direct from crude oil or from conversion units such as FCC, coker or visbreaking, or from desulphurization or hydroconversion of RAT (atmospheric residues) and / or RSV (vacuum residues), hydrocracking residues or the filler can be a deasphalted oil, or even any mixture of the aforementioned fillers. The above list is not exhaustive. In general, fillers suitable for the oil objective have an initial boiling point greater than 340 ° C, and better still greater than 370 ° C.

The nitrogen content of the feed is generally greater than 200 ppm by weight, preferably greater than 400 ppm by weight and even more preferably greater than 500 ppm by weight. The sulfur content of the feed is generally greater than 500 ppm by weight and most often greater than 1% by weight.

The feed, optionally comprising a mixture of the fillers mentioned above, is first subjected to a hydrorefining, 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 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 pressure between 5 and 25 Mpa, preferably less than 20 Mpa, the space speed being between 0.1 and 10 h ^'1 and advantageously between 0.1 and 6 h, preferably between 0.3-3h ^"1 , and the amount 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 largely eliminate two types of compounds; aromatic compounds and organic nitrogen compounds initially present in the feed.

Given the presence of organic sulfur and nitrogen present in the charging the catalyst of step (a) will operate in the presence of non-negligible quantities of NH ₃ and of H ₂ S originating respectively from the hydrodenitrogenation and from the hydrodesulfurization of the organic nitrogen and organic sulfur compounds present in the charge.

In this first step, which performs hydrodenitrogenation, hydrodesulfurization, hydrogenation of aromatics and cracking of the feed to be treated, the feed is purified while simultaneously allowing the properties of the oil base to be adjusted at the outlet of this first step. depending on 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 increase the cracking and therefore the viscosity index of the oil base. . If we consider the fraction of initial boiling point greater than 340 ° C (or even 370 ° C), at the end of this step, its viscosity index obtained after dewaxing with solvent (methyl isobutyl ketone) at about -20 ° C is preferably between 80 and 150, and better still between 90 and 140, or even 90 and 135. To obtain such indices, in general the conversion of the charge into cracked products, with boiling points below 340 °. C (see 370 ° C) is at most equal to about 60% by weight, or even at most 50% by weight.

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. Preferably, the support is acidic. 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 at least one element included in the assembly formed by the phosphorus, boron and silicon elements.

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, or else the NiMo and / or NiW catalysts on silica-alumina, or on silica-alumina-titanium oxide doped with at least one element included in the group of atoms formed by phosphorus, boron and silicon .

Even more preferred catalysts are those containing phosphorus, those containing phosphorus and boron, those containing phosphorus, boron and silicon, as well as those containing boron and silicon. The catalysts which are suitable for implementing the process according to the invention may also advantageously contain at least one element from the group VB (Niobium for example) and / or at least one element from the group VII A (fluorine for example) and or at least an element of the Vil B group (rhenium, manganese for example).

Preferably, phosphorus, boron, silicon are introduced as a promoter element.

The promoter element and, in particular the silicon introduced onto the support according to the invention, is mainly located on the matrix of the support and may be characterized by techniques such as the Castaing microprobe (distribution profile of the various elements), transmission electron microscopy coupled with an X analysis of the components of the catalyst, or even by establishing a distribution map of the elements present in the catalyst by electron microprobe. These local analyzes will provide the location of the various elements, in particular the location of the promoter element, in particular the location of the amorphous silica due to the introduction of the silicon onto the matrix of the support. The location of the silicon in the framework of the zeolite contained in the support is also revealed. In addition, a quantitative estimate of the local contents of silicon and other elements can be carried out. On the other hand, the NMR of the solid of ²⁹ Si rotating at the magic angle is a technique which makes it possible to detect the presence of amorphous silica introduced into the catalyst.

The total concentration of metal oxides of groups VIB (W, preferred Mo) and VIII (Co, Ni preferred) is between 1-40%, even 5 and 40% by weight and preferably between 7 and 30% and the ratio by weight expressed as oxide metallic between metal (or metals) of group VIB on metal (or metals) of group VIII is preferably between 20 and 1.25 and even more preferred between 10 and 2. The content of doping element in the catalyst is at least 0, 1% by weight and is less than 60%. The phosphorus (oxide) content of the catalyst is generally at most 20% by weight, preferably 0.1-15%, the boron (oxide) content is generally at most 20% by weight, preferably 0 , 1-15%, and the silicon content (oxide and non-matrix) is generally at most 20% by weight, preferably 0.1-15%.

The content of Group VII A element in the catalyst is at most 20% by weight, preferably 0.1-15%, the content of Group VII B element is at most 50% by weight, preferably 0 , 01-30% and the VB Group element content of at most 60% by weight, preferably 0.1-40%.

Advantageous catalysts according to the invention thus contain at least one element chosen from Co and Ni, at least one element chosen from Mo and W, and at least one doping element chosen from P, B, Si, said elements being deposited on a support. . Other preferred catalysts contain as doping elements phosphorus and boron deposited on an alumina-based support.

Other preferred catalysts contain as doping elements boron and silicon deposited on an alumina-based support.

Other preferred catalysts also contain phosphorus, in addition to boron and / or silicon. Preferably, all of these catalysts contain at least one element of GVIII chosen from Co and Ni, and at least one element of GVIB chosen from W and Mo.

Step (b): Separation step of the products formed

The effluent obtained at the end of this first stage is sent (stage b) to a separation train comprising a means for separating the gases (for example a gas-liquid separator) making it possible to separate gases such as hydrogen, hydrogen sulfide (H ₂ S), ammonia (NH ₃ ) formed, as well as gaseous hydrocarbons up to 4 carbon atoms. At least one effluent is then recovered containing the products with a boiling point above 340 ° C. Advantageously, after the gas-liquid separation, the effluent undergoes a separation of the compounds with a boiling point below 150 ° C. (gasoline), generally carried out by stripping and / or atmospheric distillation. Preferably, the separation step (b) ends with vacuum distillation.

The separation train can therefore be produced in different ways. It may for example include a stripper to separate the gasoline formed during step (a) and the resulting effluent is sent to a vacuum distillation column to recover at least one oil fraction and also the middle distillates.

In another embodiment, the separation train can comprise, before the vacuum distillation, an atmospheric distillation of the effluent from the separator or the stripper.

At the level of atmospheric distillation, at least one middle distillate fraction is recovered. At least one gasoline fraction is obtained at the stripper or at atmospheric distillation. The atmospheric distillation residue is sent for vacuum distillation. Vacuum distillation makes it possible to obtain the oil fraction (s) of different grades according to the needs of the operator.

There is thus obtained at least one oil fraction whose initial boiling point is greater than 340 ° C, and better still greater than 370 ° C, or even 380 ° C, or even 400 ° C.

This fraction has, after solvent dewaxing (methyl-isobutyl ketone) at around -20 ° C, a VI of at least 80 and generally between 80 and 150 and better between 90 and 140, even 90 and 135.

According to the invention, this fraction (residue) will then be treated alone or as a mixture with one or more other fractions in the catalytic dewaxing step.

Step (a) also leads to the production of compounds having lower boiling points which can be advantageously recovered during separation step (b). They include at least one gasoline cut and at least one medium distillate cut (for example 150-380 °) which generally has a pour point below -20 ° C and a cetane number greater than 48.

In another embodiment more focused on the objective of producing middle distillates with a very low pour point, the cutting point is lowered, and for example instead of cutting at 340 ° C., it is possible for example to include gas oils and optionally the kerosene in the fraction containing the compounds boiling above 340 ° C. For example, a fraction with an initial boiling point of at least 150 ° C. is obtained. This fraction will then be sent for dewaxing.

Generally speaking, in this text, middle distillates are called the fraction (s) with an initial boiling point of at least 150 ° C. and the final fraction going before the oil (the residue), c that is, generally up to 340 ° C, or preferably about 380 ° C.

Stage (c): Catalytic hydrodewaxing (HDPC) At least one fraction containing the compounds boiling above 340 ° C., as defined above, resulting from stage (b) is then subjected alone or in mixture with d other fractions resulting from the sequence of steps (a) and (b) of the process according to the invention, to a catalytic dewaxing step in the presence of hydrogen and a hydrodewaxing catalyst comprising an acid function and a function hydro-dehydrogenating metal and at least one matrix.

Note that the compounds boiling above 340 ° C. are preferably always subjected to catalytic dewaxing, whatever the mode of separation chosen in step (b).

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

The bridge width measurement is carried out using a graphics and molecular modeling tool such as Hyperchem or Biosy, 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 n-Cio of 1, 2 kPa or total pressure of 451.2 kPa in a fixed bed and with a constant n-Cιrj flow rate of 9.5 ml / h, a total flow rate 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 a hydro-dehydrogenating function will undergo hydroisomerization reactions which will produce isomerized products with 10 carbon atoms, and reactions hydrocracking leading to the formation of products containing less than 10 carbon atoms.

Under these conditions, a molecular sieve used in the hydrodewaxing stage according to the invention must have the physicochemical characteristics described above and lead, for a yield of isomerized products of n-Cio 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, ZSM-48 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.

If we consider the fraction of the effluent with an initial boiling point greater than 340 ° C. which can be obtained at the end of steps (a) and (b) of the process according to the invention and which is to be treated in this hydrodewaxing stage (c), it has the following characteristics: 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, preferably less than 20 ppm, or better still at 10 ppm by weight, a viscosity index obtained after dewaxing with solvent (methyl isobutyl ketone) at approximately - 20 ° C, which is at least equal to 80, preferably between 80 and 150, and better still between 90 and 140, or even 90 and 135, an aromatic content less than 15% and preferably less than 10% by weight, a viscosity at 100 ° C greater than or equal to 3 cSt (mm7s).

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 (or 0.2) and 25 MPa (10 ⁸ Pa) and preferably between 0.5 (1.0) and 20 MPa; - the hourly volume speed (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 and even more preferred between 0.2 and 10 h.

They are chosen so as 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.

Stage (d): Hydrofinishing (Hydrofinishing) The effluent leaving the catalytic hydrodewaxing stage is, preferably in its entirety and without intermediate distillation, sent to a hydrofinishing catalyst in the presence of hydrogen so as to produce advanced hydrogenation of aromatic compounds which affect the stability of oils and distillates. However, the acidity of the catalyst must be low enough not to lead to the excessive formation of cracking products with a boiling point below 340 ° C. so as not to degrade the final yields, in particular in 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 support does not contain a zeolite.

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. A preferred catalyst consists of noble metal, chlorine, fluorine and alumina.

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 220-320 ° C; the pressure is between 0.1 and 25 MPa (10 ⁶ Pa) and preferably between 1.0 and 20 MPa; the hourly volume speed (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.

Generally the temperature of the HDF stage is lower than the temperature of the catalytic hydrodewaxing stage (HDPC). The THDPC-THDF difference is generally between 20 and 200, and preferably between 30 and 100 ° C. Step (e): Separation

The effluent leaving the HDF stage is sent to a separation or distillation train, which comprises a separation of the gases (for example by means of a gas-liquid separator) making it possible to separate the liquid products from the gases such as hydrogen and gaseous hydrocarbons having from 1 to 4 carbon atoms. This separation train can also comprise a separation of the compounds with a boiling point below 150 ° C. (gasoline) formed during the preceding stages (for example stripping and / or atmospheric distillation). The separation step (e) ends with vacuum distillation to recover at least one oil fraction. The middle distillates formed during the preceding stages are also recovered during the separation of stage (e).

The separation train can be produced in different ways. It may for example include a stripper to separate the gasoline formed during step (a) and the resulting effluent is sent to a vacuum distillation column to recover at least one oil fraction and also the middle distillates.

At the atmospheric distillation, at least one middle distillate fraction is recovered (these are the distillates formed during the preceding steps). At least one gasoline fraction is obtained at the stripper or at atmospheric distillation. The atmospheric distillation residue is sent for vacuum distillation.

Vacuum distillation makes it possible to obtain the oil fraction (s) of different grades according to the needs of the operator.

All combinations are possible, the cutting points being adjusted by the operator according to his needs (product specifications for example). This separation also makes it possible to refine the characteristics of the oil fraction such as, for example, NOACK, viscosity, by choosing the cutting point between the diesel oil and the oil fraction.

The base oils obtained according to this process most often have a pour point less than -10 ° C, a content by weight of aromatic compounds less than 2%, an VI greater than 95, preferably greater than 105 and even more preferably greater than 120, a viscosity of at least 3 , 0 cSt at 100 ° C., an ASTM D1500 color less than 1 and preferably less than 0.5, and a UV stability such that "color increase ASTM D1500 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 ultraviolet rays. The test chamber consists of a metal enclosure provided 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. Among the samples is included a standard oil with known UV 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 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 English abbreviation of polycyclic aromatic hydrocarbons) which are toxic and present in concentrations of one part per billion by weight of aromatic compounds in 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 . These measurements are carried out with concentrations of 1 g of oil per liter, in a 1 cm tank. 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 physico-chemical properties of the white oils considered but also in their chemical composition .

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 for UV adsorption which must be less than 1.60 to 275 nm on a pure product in tanks of 1 cm and a maximum specification of absorption of the extraction products by DMSO which must be less than 0.1 for the American market (Food and Drug Administration, standard n ° 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.

In addition, medicinal white oils must also pass the carbonizable material test (ASTM D565). It consists of heating and stirring a mixture of white oil and concentrated sulfuric acid. After decantation of the phases, the acid layer must have a less intense coloring than that of a colored reference solution or that resulting from the combination of two yellow and red colored glasses.

Middle distillates from the sequence of process steps according to the invention have pour points less than or equal to -10 ° C and generally at -20 ° C, low aromatic contents (at most 2% by weight), poly aromatic contents (di and more) lower 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 of stages (c) and (d) hence the possibility of working in series and therefore of generating cost savings.

The present invention also relates to an installation which can be used for implementing the method described above. The installation includes:

- a hydrorefining zone (2) containing a hydrorefining catalyst, and having at least one line (1) for bringing the feed to be treated - a separation train comprising at least one gas separation means (4) provided with '' a pipe (3) bringing the effluent from the zone (2), said means being provided with at least one pipe (5) for the evacuation of gases, at least one means (7) for separating the compounds to boiling point below 150 ° C, said means being provided with at least one line (8) for the outlet of the fraction containing the compounds boiling below

150 ° C, and at least one line (9) for discharging an effluent containing compounds boiling at at least 150 ° C, said train also comprising at least one vacuum distillation column (10) for treating said effluent, said column being provided with at least one line (11) for the outlet of at least one oil fraction,

- a catalytic dewaxing zone (15) for treating at least one oil fraction, and provided with at least one line (16) for discharging the dewaxed effluent,

- a hydrofinishing zone (17) for treating the dewaxed effluent from the pipe (16), and provided with at least one pipe (18) for discharging the hydrofini effluent,

- a final separation train comprising at least one gas separation means (19) provided with at least one pipe (18) bringing the hydrofini effluent, said means being provided with at least one pipe (20) for the evacuation of gas, at least one means (22) for separating the compounds with a boiling point below 150 ° C., said means being at least one pipe (24) for the outlet of the fraction containing the compounds boiling below 150 ° C, and at least one line (25) for discharging an effluent containing compounds boiling at at least 150 ° C, said train also comprising at least one vacuum distillation column (26) for treating said effluent, said column being provided with at least one line (28) for the outlet of at least one oil fraction.

We will follow the description better from Figure 1.

The feedstock enters via the line (1) into the hydrorefining zone (2) which comprises one or more catalytic beds of hydrorefining catalyst, arranged in one or more reactors.

The effluent leaving via line (3) of the hydrorefining zone is sent to a separation train. According to Figure 1, this train comprises a separation means (4) for separating the light gases (H ₂ S, H ₂ , NH ₃ ... C1-C4) evacuated by the pipe (5).

The “degassed” effluent is brought by line (6) into a means for separating the compounds with a boiling point below 150 ° C., which is for example a stripper (7) provided with a line (8) for evacuate the fraction 150- and from a line (9) to bring the stripped effluent into a column (10) for vacuum distillation.

Said column makes it possible to separate at least one oil fraction discharged, for example by line (11) and by at least one line (12), it leaves at least one medium distillate fraction. Optionally, according to the needs of the operator, it can be separated from the light oil fractions of different grades leaving in FIG. 1 in the pipes (13) (14).

The oil fraction obtained in line (11) is sent to the catalytic dewaxing zone (15) which comprises one or more catalytic beds of catalytic dewaxing catalyst, arranged in one or more reactors.

The oil fractions of the pipes (13) (14) can also be sent in the area (12), alone or mixed with each other or with the heavier oil in the pipe (11).

The dewaxed effluent thus obtained is discharged in its entirety from the zone (15) via the pipe (16). It is then treated in the hydrofinishing zone (17) which comprises one or more catalytic beds of hydrofinishing catalyst, arranged in one or more reactors.

The hydrofini effluent thus obtained is discharged through line (18) to the final separation train. In FIG. 1, this train comprises a separation means (19) for separating the light gases discharged through the line (20).

The “degassed” effluent is brought through line (21) into a distillation column. In Figure 1, this is an atmospheric distillation column

(22) to separate one or more middle distillate fractions discharged by, for example, a pipe (23) and possibly a petrol fraction discharged through a pipe (24).

In Figure 1, the residue from atmospheric distillation exited through the pipe

(25) is sent to a vacuum distillation column (26) which separates one or more light oil fractions (according to the needs of the operator) discharged through at least one line, for example, a line (27) and makes it possible to recover a base oil fraction via line (28).

In Figure 2, another embodiment of the separation has been shown.

We will not describe all the elements that we will recognize from the reference signs, but only the separations. In FIG. 2, the effluent from zone (2) which has been degassed is brought via line (6) into a distillation column (30) which is here an atmospheric distillation column.

In this column are separated one or more gasoline and / or middle distillate fractions leaving via the pipes (31), (32) in FIG. 2, and the residue containing the heavy products (boiling point generally higher than

340 ° C, or even at 370 ° C or more) is evacuated through line (33). This residue is, according to FIG. 2, sent to a vacuum distillation column (10) from which an oil fraction is separated by the line (11) and possibly by one or more lines (34) (35) for example leaving a or light oil fractions of different grades, when the operator has requested them.

In FIG. 2, the final separation train comprises a gas separation means (19) in which enters the hydrofinished effluent through the pipe (18) and leaves it “degassed” through the pipe (21). This degassed effluent is sent to a stripper (36) provided with a pipe (37) for discharging the 150 ^" fraction and a pipe (38) through which the stripped effluent exits. Said effluent is sent to a distillation column under vacuum (26) which makes it possible to separate an oil-based fraction via the line (28) and at least one lighter fraction. Here, these lighter fractions are for example light oils discharged through the lines (39) (40) and a single fraction discharged through line (41) and containing petrol and middle distillates.

It will be understood that all the combinations of the separation trains are possible provided that the train includes a means for evacuating the light gases, a means for separating the fraction 150 ^′ (stripper, atmospheric distillation) and vacuum distillation to separate the fraction containing the products with a boiling point above 340 ° C (oil fraction or oil base). Generally, the vacuum columns used directly after the stripper are adjusted to separate at the top fractions with a boiling point below 340 ° C, or at 370 ° C or more (380 ° C for example). In fact, the operator will adjust the cutting points according to the products to be obtained and for example if he wants to produce light oils.

The more conventional sequence of separator, atmospheric distillation column and vacuum distillation column is more often used for the final separation train. The combination of FIG. 1 is particularly advantageous in terms of the quality of the separation (and therefore of the products obtained) for a very low cost. optimized (economy of a column).

Claims

claims

1. Process for the production of oils and middle distillates from a feed containing more than 200 ppm by weight of nitrogen and more than 500 ppm by weight of sulfur, and at least 20% of which boils above 340 ° C. , the feedstock is chosen from the group formed by vacuum distillates from direct distillation of crude oil or from conversion units, hydrocracking residues, vacuum distillates from desulfurization or hydroconversion of atmospheric residues or residues under vacuum, deasphalted oils or their mixtures, comprising the following stages:

(a) hydrorefining of the charge, carried out at a temperature of 330 ° -450 ° C, under a pressure of 5-25Mpa, with a space speed of 0.1-1 Oh ^'1 , in the presence of hydrogen in the ratio hydrogen / hydrocarbon volume of 100-2000, in the presence of an amorphous catalyst comprising a support and at least one non-noble metal from group VIII, at least one metal from group VI B, and at least one doping element chosen from the group formed by phosphorus, boron and silicon, the conversion being at most 60% by weight,

(b) from the effluent obtained in step (a) separation of the gases and the compounds with a boiling point below 1δ0 ° C, followed by a separation of the compounds with a boiling point below 1δ0 ° VS,

(c) catalytic dewaxing of at least part of the effluent at the end of step (b) and which contains compounds with a boiling point above 340 ° C., carried out at a temperature of 200 -00 ° C, under a total pressure of 1-25MPa, with an hourly volume velocity of 0.05-δ0h ^'1 , with 50-

2000I of hydrogen / l of feed, and in the presence of a catalyst comprising at least one hydro-dehydrogenating element and at least one molecular sieve,

(d) hydrofinishing at least part of the effluent from step (c) carried out at a temperature of 180-400 ° C, under a pressure of 1 -25MPa, with an hourly volume speed of 0.05 -100h ^'1 , in the presence of 50-20001 of hydrogen / l of charge, and in the presence of an amorphous catalyst at least one hydro-dehydrogenating metal and at least one halogen.

2. Method according to claim 1, in which the hydrorefining catalyst contains at least one element chosen from Co and Ni, at least one element chosen from Mo and W, and at least one doping element chosen from P, B, Si, said elements being deposited on a support.

3. Method according to one of claims 1 or 2, wherein the hydrorefining catalyst contains as doping elements phosphorus and boron deposited on an alumina-based support.

4. Method according to one of claims 1 or 2, wherein the hydrorefining catalyst contains as doping elements boron and silicon deposited on a base based alumines.

δ. The method of claim 4 in which the catalyst also contains phosphorus.

6. Method according to one of the preceding claims wherein the support of the hydrorefining catalyst is an acid support.

7. Method according to one of the preceding claims, in which the hydrorefining catalyst also contains at least one element chosen from the group formed by elements of group VB, elements of group VIIA and elements of group VIIB.

8. The method of claim 7 wherein the hydrorefining catalyst contains at least one element selected from niobium, fluorine, manganese, rhenium.

9. Method according to one of the preceding claims, in which the molecular sieve of step (c) is chosen from the group of zeolites formed by ferrierite, NU-10, EU-13, EU-1, ZSM-48 and zeolites of the same structural type.

10. Method according to one of the preceding claims, in which the hydrofinishing catalyst contains at least one group VIII metal and / or at least one group VIB metal, a support devoid of zeolite and at least one group VIIA element.

11. The method of claim 10 wherein the catalyst contains platinum, chlorine and fluorine.

12. Method according to one of the preceding claims wherein in the hydrorefining step, the conversion into products with boiling points below 340 ° C is at most equal to δ0% by weight.

13. Method according to one of the preceding claims wherein step (b) and / or step (e) is carried out by gas-liquid separation, then stripping followed by vacuum distillation.

14. The method of claim 13 wherein step (b) and / or step (e) is carried out by gas-liquid separation, then atmospheric distillation followed by vacuum distillation.

1 δ. Process according to one of the preceding claims, in which the feedstock is chosen from the group formed by vacuum distillates from direct distillation of crude oil or from conversion units, hydrocracking residues, vacuum distillates from desulfurization or hydroconversion of atmospheric residues or residues under vacuum or their mixtures.

16. Installation for the production of oils and middle distillates comprising: - a hydrorefining zone (2) containing a hydrorefining catalyst, and having at least one line (1) for bringing the feed to be treated

- a separation train comprising at least one gas separation means (4) provided with a pipe (3) bringing the effluent from the zone (2), said means being provided with at least one pipe (5) for the evacuation of gases, at least one means (7) for separating the compounds with a boiling point below 150 ° C., said means being provided with at least one line (8) for the outlet of the fraction containing the compounds boiling below 1δ0 ° C, and at least one line (9) for discharging an effluent containing compounds boiling at at least 1δ0 ° C, said train also comprising at least one vacuum distillation column (10) for treating said effluent, said column being provided with at least one pipe (11) for the outlet of at least one oil fraction,

- a catalytic dewaxing zone (1δ) for treating at least one oil fraction, and provided with at least one line (16) for discharging the dewaxed effluent,

- a final separation train comprising at least one gas separation means (19) provided with at least one pipe (18) bringing the hydrofini effluent, said means being provided with at least one pipe (20) for the gas evacuation, at least one means (22) for separating the compounds with a boiling point below 1 δ0 ° C, said means being at least one line (24) for the outlet of the fraction containing the compounds boiling at - Below 1δ0 ° C, and at least one line (25) for discharging an effluent containing compounds boiling at at least 150 ° C, said train also comprising at least one vacuum distillation column (26) for treating said effluent, said column being provided with at least one pipe (28) for the outlet of at least one oil fraction.

17. Installation according to claim 16 wherein the gas separation means (4) (19) is a gas-liquid separator.

18. Installation according to one of claims 16 or 17 in which the separation means (7) of the compounds with a boiling point below 150 ° C is a stripper and that the stripped effluent discharged through the pipe (9) is sent to a vacuum distillation column (10), provided with at least one line (11) for discharging at least one oil fraction and at least one line (12) for the outlet of at least one medium distillate fraction .

19. Installation according to one of claims 16 or 17 in which the separation means (22) of the compounds with a boiling point below 150 ° C is an atmospheric distillation, provided with at least one pipe (23) for evacuating at least one middle distillate fraction, at least one line (24) for discharging at least one gasoline fraction, and at least one line

(25) for the outlet of the residue, the said being sent to a vacuum distillation column (26) separating at least one oil fraction discharged through at least one line (28).