FR2792946A1 - Base oil and middle distillate production comprises successive conversions of hydro-isomerization and catalytic deparaffination - Google Patents

Abstract

The production of high quality base oils and middle distillates, particularly gasoils, comprises successive conversions of hydro-isomerization and catalytic deparaffination. The production of oils comprises: (a) conversion of the charge, with simultaneous hydro-isomerization of n-paraffins, the charge having a sulfur content less than 1000 ppm, a nitrogen content less than 200 ppm, a metal content less than 50 ppm and an oxygen content no more than 0.2%, carried out at 200-500 deg C, 5-25 MPa and VVH of 0.1-5 h<-1>, in the presence of H2 and a catalyst containing a noble metal deposited on an amorphous acid support, the dispersion of the metal being less than 20%; and (b) catalytic deparaffination of at least part of the effluent (preferably all) from (a) at 200-500 deg C, 1-25 MPa and VVH of 0.05-50 h<-1>, in the presence of 50-2000/H2/l of effluent and a catalyst comprising a hydro-dehydrogenating element and a molecular sieve.

Description

The present invention relates to an improved process for the manufacture of oils.

very high quality base, that is to say having a high viscosity index (Vl), good UV stability and a low pour point, from hydrocarbon feeds and preferably from hydrocarbon feeds resulting from the Fischer process -Tropsch, with possibly simultaneously the production of middle distillates (gas oils, kerosene in particular) of very high quality, that is to say

possessing a low pour point and a high cetane number.

Background Art High quality lubricants are of paramount importance for the good

operation of modern machinery, automobiles, and trucks.

These lubricants are most often obtained by a succession of refining steps allowing the improvement of the properties of a petroleum cut. In particular, treatment of heavy petroleum fractions with high linear or slightly branched paraffin content 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 or very thin paraffins. not very 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 oils lead to high pour points and therefore to freezing phenomena for low temperature uses. In order to decrease the values of the pour points, these linear paraffins not or very little connected must be entirely or

partially eliminated.

Another means is the catalytic treatment in the presence or absence of hydrogen and, given their shape selectivity, zeolites are among the

most used catalysts.

Zeolite-based catalysts such as ZSM-5, ZSM-11, ZSM-12, ZSM-

22, ZSM-23, ZSM-35 and ZSM-38 have been described for their use in these

processes.

All the catalysts currently used in hydroisomerization are of the bifunctional type combining an acid function with a hydrogenating function. The acid function is provided by supports of large surfaces (150 to 800 m2.g'1 generally) having a surface acidity, such as halogenated aluminas (chlorinated or fluorinated in particular), phosphorus aluminas, combinations of boron oxides and aluminum, amorphous silica-aluminas and silica-aluminas. The hydrogenating function is provided either by one or more metals from group VIII of the periodic table of the elements, such as iron, cobalt, nickel, ruthenium, rhodium, palladium, osmium, iridium and platinum, or by a combination of at least one group VI metal such as chromium, molybdenum and

tungsten and at least one metal from group VIII.

The balance between the two acid and hydrogenating functions is the fundamental parameter which governs the activity and the selectivity of the catalyst. A weak acid function and a strong hydrogenating function give catalysts which are not very active and selective towards isomerization, whereas a strong acid function and a weak hydrogenating function give catalysts which are very active and selective towards cracking. A third possibility is to use a strong acid function and a strong hydrogenating function in order to obtain a very active catalyst but also very selective towards isomerization. It is therefore possible, by judiciously choosing each of the functions, to adjust the activity / selectivity pair of the catalyst. The Applicant therefore proposes, according to the process described in the invention, to jointly produce middle distillates of very good quality, VIl oil bases and pour point at least equal to those obtained with a process.

hydrorefining and / or hydrocracking.

Object of the invention The Applicant has focused its research efforts on the development of an improved process for manufacturing very high quality lubricating oils and high quality middle distillates from hydrocarbon feedstocks and preferably from

from hydrocarbon feeds resulting from the Fischer-Tropsch process.

The present invention therefore relates to a sequence of processes for the joint manufacture of very high quality base oils and very high quality middle distillates (gas oils in particular). The oils obtained have a high viscosity index (VI), low volatility, good UV stability and a low pour point, from petroleum cuts and preferably from fillers.

hydrocarbons from the Fischer-Tropsch process.

More specifically, the invention relates to a process for the production of oils from a hydrocarbon feed (preferably at least 20% by volume has a boiling point of at least 340 ° C.), said process comprising the following successive steps: (a) conversion of the feed with simultaneous hydroisomerization of the n-paraffins of the feed, said feed having a sulfur content of less than 1000 ppm by weight, a nitrogen content of less than 200 ppm by weight, a metal content less than 50 ppm by weight, an oxygen content of at most 0.2% by weight, said step taking place at a temperature of 200-500 C, under a pressure of 5 MPa, with a space velocity of 0.1 - 5 h - ', in the presence of hydrogen, and in the presence of a catalyst containing at least one noble metal deposited on an amorphous acidic support, the

noble metal dispersion being less than 20%.

(b) catalytic dewaxing of at least part of the effluent from step a), carried out at a temperature of 200 - 500 C, under a pressure of 1-25 MPa, with an hourly volume speed of 0, 05-50h1- ', in the presence of 50-2000 liter of hydrogen / liter of effluent entering step (b) and in the presence of a catalyst comprising at least one hydro-dehydrogenating element and at least one molecular sieve . Step (a) is therefore optionally preceded by a hydrotreatment step generally carried out at a temperature of 200-450 C, under a pressure of 2 to Mpa, with a space velocity of 0.1-6h- ', in the presence of 'hydrogen in the hydrogen / hydrocarbon volume ratio of 100-2000 I / 1, and in the presence of an amorphous catalyst comprising at least one metal from group VIII and at least one metal from group VII B. Step (a) is advantageously followed by separation of the light gases from the effluent

obtained at the end of step (a).

Preferably, the effluent resulting from the hydroisomerization treatment is subjected to a distillation step (preferably atmospheric) so as to separate the compounds having a boiling point of less than 340 ° C. (gas, gasoline, kerosene, gas oil) from the products having an initial boiling point greater than at least 340 C and which form the residue. At least one middle distillate fraction having a pour point of at most -20 ° C. and a cetane number of at least 50 is thus separated. Step (b) of catalytic dewaxing then applies at least to residue at the end of the distillation which contains compounds with a boiling point greater than at least 340 C. In another embodiment of the invention, the effluent resulting from stage (a) is not distilled before carrying out step (b). At most, it undergoes a separation of at least part of the light gases (by flash ....) and it is then subjected

to catalytic dewaxing.

Preferably, step (b) is carried out with a catalyst containing at least one molecular sieve, the microporous system of which has at least one main type of channels with pore openings having 9 or 10 T atoms. T being chosen from the group formed. by Si, Al, P, B, Ti, Fe, Ga, alternating with an equal number of oxygen atoms, the distance between two pore openings accessible to 9 or 10 atoms

T being at most 0.75 nm, and said sieve exhibiting in the n-decane test a 2-

methylnonane / 5-methylnonane greater than 5.

Advantageously, the effluent resulting from the dewaxing treatment is subjected to a distillation step advantageously comprising atmospheric distillation and vacuum distillation so as to separate at least one oil fraction at a boiling point above at least 340 C. It most often has a pour point less than -10 C and a Vl greater than 95, a viscosity at 100 C of at least 3cSt (ie 3mm2 / s). This distillation step is essential when there is no

no distillation between steps (a) and (b).

Detailed description of the invention

The process according to the invention comprises the following steps: The feed The hydrocarbon feed from which the oils and optionally the high quality middle distillates are obtained preferably contains at least 20% by volume boiling above 340 C, of preferably at least 350 C and advantageously at least 380 C. This does not mean that the boiling point

is 380 C or more, but 380 C or more.

The filler contains n-paraffins. Preferably the feed is an effluent from a Fischer-Tropsch unit. A wide variety of loads can be handled by the process. The feed can also be, for example, vacuum distillates resulting from the direct distillation of the crude or from conversion units such as FCC, coker or visbreaking, or coming from aromatic extraction units, or coming from desulfurization or hydroconversion of RAT (atmospheric residues) and / or RSV (vacuum residues), or the feed may be a deasphalted oil, or a hydrocracking residue, for example resulting from DSV or any mixture of

previously cited charges. The above list is not exhaustive.

In general, fillers suitable for the purpose oils have an initial boiling point.

above at least 340 C and better still above at least 370 C.

The feed introduced in the conversion-hydroisomerization step (a) must be clean. By clean feed we mean feeds whose sulfur content is less than 1000 ppm by weight and preferably less than 500 ppm by weight and even more preferably less than 300 ppm by weight or better than 200 ppm by weight. The nitrogen content is less than 200 ppm by weight and preferably less than 100 ppm by weight and even more preferably less than 50 ppm by weight. Content

in metals of the charge such as nickel and vanadium is extremely reduced i.e.

say less than 50 ppm by weight and more advantageously less than 10 ppm

weight, or better still less than 2 ppm by weight.

In the case where the contents of unsaturated or oxygenated products are liable to cause too great a deactivation of the catalytic system, the feed (for example resulting from the Fischer-Tropsch process) must, before entering the hydroisomerization zone, undergo hydrotreatment in a hydrotreatment zone. Hydrogen is reacted with the feed in contact with a hydrotreatment catalyst whose role is to reduce the content of hydrocarbon molecules

unsaturated and oxygenated (produced for example during the Fischer synthesis)

Tropsch).

The oxygen content is thus reduced to at most 0.2% by weight.

In the case where the feed to be treated is not specific in the sense defined above, it is first subjected to a prior hydrotreatment step, 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 VIB and at least one element from group VIII, at a temperature between 200 and 450 C, of preferably 250-450 C, advantageously 330-450 C or 360-420 C, under a pressure of between 5 and 25 MPa or better still less than 20 MPa, preferably between 5 and 20 MPa, the space speed being between 0.1 and 6 h- ', preferably 0.3-3h-', and the quantity of hydrogen introduced is such that the ratio

hydrogen / hydrocarbon volume is between 100 and 2000 liters / liter.

The support is generally based (preferably consisting essentially of) alumina or amorphous silica-alumina; it can also contain boron oxide, magnesia, zirconia, titanium oxide or a combination of these oxides. The hydrodehydrogenating function is preferably filled with at least one metal or metal compound from groups VIII and VIB, preferably chosen from among

; 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: ease of preparation during, in particular, the impregnation of

nickel and molybdenum solutions, and better hydrogenation activity.

The preferred catalysts are NiMo and / or NiW catalysts on alumina, also 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 also NiMo and / or NiW catalysts on silica-alumina, or on silica-alumina-titanium oxide doped or not with at least one element included

in the group of atoms formed by phosphorus, boron, fluorine and silicon.

The total concentration of oxides of metals from groups VIB and VIII is between 5 and 40% by weight and preferably between 7 and 30% and the weight ratio expressed as metal oxide between metal (or metals) of group VI on metal (or metals) of group VIII is preferably between 20 and 1.25 and even more preferably between 10 and 2. The concentration of phosphorus oxide P20s will be lower

at 15% by weight and preferably at 10% by weight.

The product obtained at the end of the hydrotreatment undergoes, if necessary, an intermediate separation of water (H20), H2S and NH3 so as to bring the water, H2S and NH3 contents to values respectively lower than plus 100 ppm, 200 ppm, ppm in the feed introduced in step (a). We can at this level optionally provide for separations of products having a boiling point below 340 C

so as to treat in step (a) only one residue.

Step (a): Hydroisomerization-Conversion The Catalyst Step (a) takes place in the presence of hydrogen and in the presence of a bifunctional catalyst comprising at least one noble metal deposited on an acid support

amorphous, the noble metal dispersion being less than 20%.

During this step, the n-paraffins in the presence of a bifunctional catalyst undergo isomerization and then optionally hydrocracking to lead respectively to the formation of isoparaffins and lighter cracking products.

such as gas oils and kerosene.

Preferably, the fraction of the noble metal particles having a size less than 2

nm represents at most 2% by weight of the noble metal deposited on the catalyst.

Advantageously, at least 70% (preferably at least 80%, and better still at least%) of the noble metal particles have a size greater than 4 nm (% number). The support is amorphous, it does not contain a molecular sieve; the catalyst does not

also does not contain molecular sieve.

The amorphous acidic support is generally chosen from the group formed by a silica-alumina, a halogenated alumina (preferably fluorinated), an alumina doped with silicon (deposited silicon), a mixture of titanium oxide alumina, a sulphated zirconia, a doped zirconia. with tungsten, and their mixtures with one another or with at least one amorphous matrix chosen from the group formed by alumina, titanium oxide,

silica, boron oxide, magnesia, zirconia, clay for example.

Io A preferred catalyst, according to the invention, comprises (preferably consists essentially of) 0.05 to 10% by weight of at least one noble metal of group VIII deposited

on an amorphous silica-alumina support.

The characteristics of the catalyst are in more detail Silica content: the preferred support used for the preparation of the catalyst described in

the scope of this patent is composed of silica SiO2 and Al2O3 alumina from the synthesis.

The silica content of the support, expressed as a percentage by weight, is generally between 1 and 95%, advantageously between 5 and 95% and preferably between 10 and 80% and even more preferably between 20 and 70% or even between 22. and 45%. This content is perfectly measured using X-ray fluorescence. Nature of the noble metal: for this particular type of reaction, the metallic function is provided by at least one noble metal from group VIII of the periodic table.

elements and more particularly platinum and / or palladium.

Noble metal content: the noble metal content, expressed in% by weight of metal relative to the catalyst, is between 0.05 to 10 and more preferably

between 0.1 and 5.

Dispersion of the noble metal: the dispersion, representing the fraction of metal accessible to the reactant relative to the total amount of metal in the catalyst, can be measured, for example, by HJO2 titration. The metal is reduced beforehand, that is to say that it undergoes a treatment under a flow of hydrogen at high temperature under these conditions such that all the platinum atoms accessible to the hydrogen are transformed into metallic form. Then, a flow of oxygen is sent under suitable operating conditions so that all the reduced platinum atoms accessible to oxygen are oxidized in the form of PtO2. By calculating the difference between the quantity of oxygen introduced and the quantity of oxygen leaving, we can access the quantity of oxygen consumed; thus, it is then possible to deduce from this latter value the quantity of platinum accessible to oxygen. The dispersion is then equal to the ratio

quantity of platinum accessible to oxygen over the total quantity of platinum in the catalyst.

In our case, the dispersion is less than 20%, it is generally higher

at 1% or better at 5%.

Particle size measured by Transmission Electron Microscopy: in order to determine the size and distribution of the metal particles we used Transmission Electron Microscopy. After preparation, the catalyst sample is finely ground in an agate mortar and then it is dispersed in ethanol by ultrasound. Samples at different places to ensure good representativeness in size are taken and placed on a copper grid covered with a thin carbon film. The grids are then dried in air under an infrared lamp before being introduced into the microscope for observation. In order to estimate the average size of the noble metal particles, several hundred measurements are taken from several dozen images. All of these

measurements allows a histogram of particle size distribution to be produced.

Thus, we can accurately estimate the proportion of particles corresponding to

each particle size domain.

Distribution of the noble metal: the distribution of the noble metal represents the distribution of

metal inside the catalyst grain, the metal being able to be well or poorly dispersed.

Thus, it is possible to obtain the poorly distributed platinum (for example detected in a ring whose thickness is clearly less than the radius of the grain) but well dispersed, that is to say that all the platinum atoms, located in crown, will be

accessible to reagents. In our case, the distribution of platinum is good, i.e.

say that the platinum profile, measured according to the Castaing microprobe method, has a distribution coefficient greater than 0.1, advantageously greater than

0.2 and preferably greater than 0.5.

3 5 BET surface: the BET surface of the support is generally between 100 m2 / g and 500 m2 / g and preferably between 250 m2 / g and 450 m2 / g and for I0 supports

based on silica alumina, even more preferably between 310 m2 / g and 450 m2 / g.

Overall pore volume of the support: for supports based on silica alumina, it is generally less than 1.2 ml / g and preferably between 0.3 and 1.1 ml / g and even more advantageously less than 1.05 ml / g. The preparation and shaping of the silica-alumina and of any support in general is carried out by usual methods well known to those skilled in the art. Advantageously, prior to the impregnation of the metal, the support can undergo a calcination such as for example a heat treatment at 300-750 C (600 C preferred) for a period of between 0.25 and 10 hours (2 hours preferred). ) under 0-30%

volume of water vapor (approximately 7.5% preferred for silica-alumina).

The metal salt is introduced by one of the usual methods used to deposit the metal (preferably platinum) on the surface of a support. One of the preferred methods is dry impregnation which consists in introducing the metal salt into a volume of solution which is equal to the pore volume of the mass of catalyst to be impregnated. Before the reduction operation and to obtain the size distribution of the

metal particles, the catalyst undergoes calcination in humidified air at 300-

750 C (550 C preferred) for 0.25-10 hours (2 hours preferred). The partial pressure of H2O during calcination is for example 0.05 bar to 0.50 bar (0.15 bar preferred). Other known treatment methods making it possible to obtain the

dispersion of less than 20% are suitable in the context of the invention.

In this step (a) the conversion is most often accompanied by hydroisomerization of the paraffins. The process has the advantage of flexibility: depending on the degree of conversion, the production is more directed towards oils or distillates

means. The conversion generally varies between 5-90%.

Before use in the conversion reaction, the metal contained in the catalyst is reduced. One of the preferred methods for carrying out the reduction of the metal is the treatment under hydrogen at a temperature of between 150 ° C. and 650 ° C. and a total pressure of between 0.1 and 25 MPa. For example, a reduction consists of a plateau at 150 C for 2 hours then a rise in temperature to 450 C at a rate of 1 C / min then a plateau of 2 hours at 450 C; throughout this reduction step, the hydrogen flow rate is 1000 l hydrogen / catalyst. Let us denote It

also that any ex-situ reduction method is suitable.

The operating conditions under which this step (a) is carried out are important. The pressure will be maintained between 2 and 25 MPa and preferably 2 (or 3) to 20 MPa and advantageously from 2 to 18 MPa, the space speed will be between 0.1 h-1 and h-1 and preferably between 0, 2 and 1 Oh- 'is advantageously between 0.5 and 5.0h-1. And Io a hydrogen rate of between 100 and 2000 liters of hydrogen per liter of load

and preferably between 150 and 1500 liters of hydrogen per liter of feed.

The temperature used in this step is between 200 and 450 C and preferably from 250 C to 450 C, advantageously from 300 to 450 C, and again

more preferably above 340 C, for example between 320-450 C.

The hydrotreatment and conversion steps can be carried out on the two types of catalyst in (two or more) different reactors, or / and on at

at least two catalytic beds installed in the same reactor.

Treatment of the effluent from step (a) The effluent from step (a) of conversion can in its entirety be treated in step (b) of dewaxing. At the most, it can undergo a separation of at least part (and preferably at least a major part) of light gases which comprise the hydrogen, ammonia and hydrogen sulphide optionally formed, and optionally of the gases. compounds with not more than 4 carbon atoms. Hydrogen can be

separated beforehand.

Advantageously, the effluent is distilled so as to separate the light gases and also to separate at least one residue containing the compounds with a boiling point greater than

minus 340 C. This is preferably atmospheric distillation.

One can advantageously distill to obtain several fractions (gasoline, kerosene, gas oil for example), with a boiling point of at most 340 C and a fraction (called residue) with an initial boiling point higher than at least 340 C and better

above 350 C and preferably at least 3700C or 380 C.

According to a preferred embodiment of the invention, this fraction (residue) will then be treated in

the step of catalytic dewaxing, that is to say without undergoing vacuum distillation.

But in another embodiment, vacuum distillation can be used. In an embodiment more focused on an objective of producing middle distillates, and still according to the invention, it is possible to recycle part of the residue

from the separation step to the reactor containing the conversion catalyst

nO hydroisomerization so as to convert it and increase the production of middle distillates. In general, in this text we call middle distillates, the fraction (s) to

initial boiling point of at least 150 C and final up to before the residue, that is

say generally up to 340 C, 350 C or preferably less than 370 C or

380 C.

The effluent from step (a) can undergo, before or after distillation, other treatments

such as for example an extraction of at least part of the aromatic compounds.

Step (b): Catalytic hydrodewaxing At least part of the effluent from step (a), effluent which may have undergone the eVt separations / or treatments described above, is then subjected to a catalytic dewaxing step in the presence hydrogen and a catalyst

hydrodewaxing comprising an acid function, a hydro- metal function

dehydrogenating agent and at least one matrix.

Note that compounds boiling above at least 340 C are always

subjected to catalytic dewaxing.

The catalyst The acid function is provided by at least one molecular sieve and preferably a molecular sieve whose microporous system has at least one main type of channels whose openings are formed of rings which contain 9 or 10 T atoms. are the tetrahedral atoms constituting the molecular sieve and may be at least one of the elements contained in the following set of atoms (Si, Al, P, B, Ti, Fe, Ga). In the rings that make up 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 9 or 10 oxygen atoms or formed of rings which contain 9 or 10 T atoms. The molecular sieve entering into the composition of the hydrodewaxing catalyst can also have other types of channels but whose openings are formed

rings that contain less than 10 T atoms or oxygen atoms.

The molecular sieve entering into the composition of the preferred catalyst also has a bridge width, distance between two pore openings, as defined above, which is at most 0.75 nm (lnm = 10-9 m) preferably between 0.50 nm and 0.75 nm, even more preferably between 0.52 nm and 0.73 nm; such sieves make it possible to obtain good catalytic performance in

the hydrodewaxing step.

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

of the elements present in the frame of the screen, to measure the width of the bridge.

The preferred catalyst suitable for this process can also be characterized by a catalytic test called the standard test for conversion of pure n-decane which is carried out under a partial pressure of 450 kPa of hydrogen and a partial pressure of n-Clo of 1, 2. kPa i.e. a total pressure of 451.2 kPa in a fixed bed and with a constant flow of n-C10 of 9.5 ml / h, a total flow of 3.6 I / h and a mass of catalyst of 0.2 g . The reaction is carried out in a descending flow. The conversion rate is controlled by the temperature at which the reaction takes place. The catalyst subjected to said test is

consisting of pure pelletized zeolite and 0.5% by weight of platinum.

N-decane in the presence of the molecular sieve and of a hydro-

dehydrogenating will undergo hydroisomerization reactions which will produce isomerized products with 10 carbon atoms, and hydrocracking reactions

leading to the formation of products containing less than 10 carbon atoms.

Under these conditions a molecular sieve used in the hydrodewaxing step

with the preferred catalyst according to the invention must have the physical characteristics

chemicals described above and lead, for a yield of isomerized products of n-C10 of the order of 5% by weight (the conversion rate is controlled by the temperature), to 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 below

above, among the many molecular sieves already existing, allows in particular the production of products with a low pour point and high viscosity index with

good yields in the context of the process according to the invention.

The molecular sieves which may enter into the composition of the preferred catalytic hydrodewaxing catalyst are, by way of example, the following zeolites:

Ferrierite, NU-10, EU-13, EU-1.

Preferably, the molecular sieves entering into the composition of the hydrodewaxing catalyst are included in the group formed by ferrierite and

EU-1 zeolite.

In general, the hydrodewaxing catalyst comprises a zeolite chosen from the group formed by NU-10, EU-1, EU-13, ferrierite, ZSM-22, Theta-1,

ZSM-50, NU-23, ZSM-35, ZSM-38, ZSM-23, ISI-1, KZ-2, ISI-4, KZ-1.

The molecular sieve content by weight in the hydrodewaxing catalyst is between 1 and 90%, preferably between 5 and 90% and even more.

preferred 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 can be used to achieve

the shaping operation.

The catalyst also comprises a hydro-dehydrogenating function provided, for example, by at least one element from group VIII and preferably at least one noble element included in the group 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 metal not

noble 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 so

even more preferred 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.

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

phosphorus is particularly advantageous.

The treatment A residue obtained at the end of stage (a) and of the distillation and which is interesting to treat in this hydrodewaxing stage (b), 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 viscosity index of 35 to 165 (before dewaxing), preferably at least equal to 110 and even more preferably less than 150, a viscosity at 100 C greater than or equal to 3 cSt (mm2 / s), an aromatic content less than 10% by weight, a nitrogen content less than 10 ppm by weight, a sulfur content less than 50 ppm weight or better at 10

ppm wt.

The operating conditions under which the catalytic step of the process of the invention takes place are as follows: the reaction temperature is between 200 and 500 C and preferably between 250 and 470 C, advantageously 270-430 C; - The pressure is between 0.1 and 25 MPa (106 Pa) and preferably between 1.0 and 20 MPa; - the hourly volume speed (wvvh expressed in volume of feed injected per unit volume of catalyst and per hour) is between approximately 0.05 and approximately and preferably between approximately 0.1 and approximately 20 h - 'and even more more

preferred between 0.2 and 10 hrs.

They are chosen to obtain the desired pour point.

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 feed is between 50 and approximately 2000 liters of hydrogen per liter of feed and

preferably between 100 and 1500 liters of hydrogen per liter of feed.

The effluent obtained The effluent at the outlet of hydrodewaxing step (b) is sent to the distillation train, which preferably incorporates atmospheric distillation and vacuum distillation, the purpose of which is to separate the products of conversion of a boiling point of less than 340 C and preferably less than 370 C, (and including in particular those formed during the catalytic hydrodewaxing step), and of separating the fraction which constitutes the oil base and of which the initial point boiling point is greater than at least

340 C and preferably greater than or equal to 370 C.

In addition, this vacuum distillation section makes it possible to separate the different

grades of oils.

Preferably, before being distilled, the effluent at the outlet of catalytic hydrodewaxing step (b) is, at least in part and preferably in its entirety, sent to a hydrofinishing catalyst (hydrofinishing) in presence of hydrogen so as to achieve a thorough hydrogenation of aromatic compounds which adversely affect the stability of oils and distillates. However, the acidity of the catalyst must be low enough not to lead to the formation of a cracking product with a boiling point below 340 ° C. so as not to

degrade the final yields, in particular for 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 metal functions: platinum and / or palladium, or nickel-

tungsten, nickel-molydbene will be advantageously used to produce a

advanced hydrogenation of aromatics.

These metals are deposited and dispersed on a support of amorphous or crystalline oxide type, such as, for example, aluminas, silicas, silica-aluminas. The hydrofinishing catalyst (HDF) can also contain at least one element from group VII A of the Periodic Table of the 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% by weight, advantageously

0.01 to 15%, or alternatively to 0.01 to 10%, preferably 0.01 to 5%.

Among the catalysts that can be used in this hydrofinishing step, and leading to excellent performance, and in particular for obtaining medicinal oils, mention may be made of catalysts containing at least one noble metal from group VIII (platinum for example) and at least one halogen (chlorine and / or fluorine), the combination

chlorine and fluorine being preferred.

The operating conditions under which the hydrofinishing step of the process of the invention takes place are as follows: the reaction temperature is between 180 and 400 C and preferably between 210 and 350 C, advantageously 230-320 C ; - The pressure is between 0.1 and 25 Mpa (106 Pa) and preferably between 1.0 and Mpa; - the hourly volume speed (vvh expressed as volume of feed injected per unit volume of catalyst and per hour) is between approximately 0.05 and approximately

and preferably between about 0.1 and about 30 hrs.

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 feed is between 50 and approximately 2000 liters of hydrogen per liter of feed and

preferably between 100 and 1500 liters of hydrogen per liter of feed.

Advantageously, the temperature of the hydrofiniton (HDF) step is lower than the

temperature of the catalytic hydrodewaxing (HDPC) step. The THDPC- difference

THOF is generally between 20 and 200, and preferably between 30 and 100 C.

The effluent at the HDF outlet is sent to the distillation train.

The products The base oils obtained according to this process have a pour point of less than -10 C, a Vl greater than 95, preferably greater than 110 and even more preferably greater than 120, a viscosity of at least 3 , 0 cSt at 100 C, an ASTM color less than 1 and UV stability such as increased

ASTM color is between 0 and 4 and preferably between 0.5 and 2.5.

The UV Stability Test, adapted from ASTM D925-55 and Dl114855 methods, provides a quick method to compare the stability of lubricating oils exposed to a source of ultraviolet light. The test chamber consists of a metal enclosure fitted with a turntable which receives the oil samples. A bulb that produces the same ultraviolet rays as sunlight and

placed at the top of the test chamber is facing downward on the samples.

Among the samples is included a standard oil with known U.V characteristics.

The ASTM D1500 color of the samples is determined at t = 0 then after 45 h of exposure to 55 C. The results are transcribed for the standard sample and the test samples as follows: a) initial ASTM D1 500 color, b) ASTM D1500 final color, c) color enhancement, d) cloudiness,

e) precipitated.

The middle distillates obtained have improved pour points (at most -20 C),

a cetane number greater than 50, and even greater than 52.

Figure 1 The method is illustrated in Figure 1 showing the treatment of a load, by

example, from the Fischer-Tropsch process.

In Figure 1, the feed enters through line (1) into a hydrotreatment zone (2) (which may be composed of one or more reactors, and include one or more catalytic beds of one or more catalysts) into which enters hydrogen

(for example via line (3)) and the hydrotreatment step is carried out.

The hydrotreated feed is transferred via line (4) to the hydroisomerization zone (7) (which may be composed of one or more reactors, and comprise one or more catalytic beds of one or more catalysts) o is carried out, in the presence of hydrogen, step (a) of hydroisomerization. Hydrogen

can be brought through the pipe (8).

In this figure, before being introduced into zone (7), the feedstock to be hydroisomerized is freed of a large part of its water in the tank (5), the water leaving through the pipe (6) and possibly of ammonia and hydrogen sulfide H2S, in the

case where the feed which enters via line 1 contains sulfur and nitrogen.

The effluent from zone (7) is sent through a pipe (9) to a balloon (10) for separation of the hydrogen which is extracted through a pipe (11), the effluent is then distilled at atmospheric pressure in column (12) o is extracted at the top through line (13) a light fraction containing compounds with at most 4 atoms of

carbon and those boiling below (NH3, H2S etc ...).

It is also obtained at least one gasoline fraction (14) and at least one fraction

middle distillate (kerosene (15) and gas oil (16) for example).

A fraction containing the compounds with a boiling point greater than at least 340 C. is obtained at the bottom of the column. This fraction is discharged through the pipe.

(17) to the catalytic dewaxing zone (18).

The catalytic dewaxing zone (18) (comprising one or more reactors, one or more catalytic beds of one or more catalysts) also receives

hydrogen via a pipe (19) to carry out step (b) of the process.

The effluent obtained leaving through line (20) is separated in a distillation train comprising, in addition to the flask (21) for separating the hydrogen via a line (22), an atmospheric distillation column (23) and a vacuum column (24) which treats the atmospheric distillation residue transferred via line (25), a residue with an initial boiling point greater than 340 C. It is obtained as products at the end of the distillations, an oil fraction (line 26) and lower boiling fractions, such as diesel fuel (line 27), kerosene (line 28) gasoline (line 29); the light gases being eliminated through line (30) of the atmospheric column and through line (31) of the vacuum distillation column. The effluent leaving through line (20) can advantageously be sent to a hydrofinishing zone (not shown) (comprising one or more reactors, one or more catalytic beds of one or more catalysts). Hydrogen can be added if needed in this area. The outgoing effluent is then transferred to the flask

(21) and the distillation train described.

In order not to overwhelm the figure, the recycling of hydrogen has not been shown, whether at the level of the flask (10) towards the hydrotreatment and / or the hydroisomerization, and / or the

level of the balloon (21) towards the dewaxing and / or the hydrofinishing.

Example 1 Preparation of catalyst A1 in accordance with the invention The support is a silica-alumina used in the form of extrudates. It contains 29.3% by weight of silica SiO2 and 70.7% by weight of alumina Al O3. The silica-alumina, before adding the noble metal, has a surface area of 330 m2 / g and its total pore volume is 0.87 cm3 / g. The corresponding catalyst A is obtained after impregnation of the noble metal on the support. The platinum salt Pt (NH3) 4Cl2 is dissolved in a volume of solution corresponding to the total pore volume to be impregnated. The solid is then calcined for 2 hours in humidified air (partial pressure of H2O = 0.15 bar) at 550 C. The platinum content is 0.60% by weight. The pore volume, measured on the catalyst, is equal to 0.82 cm3 / g, the BET surface area, measured on the catalyst, equal to 287 m2 / g and the mean diameter of the mesopores, measured on the catalyst, is 7 nm. The pore volume corresponding to the pores whose diameter is between 4 nm and 10 nm is 0.37 cm3 / g, ie 44% of the total pore volume. The dispersion of the platinum measured by HOO 2 titration is 19%. The results obtained by local analyzes on Transmission Electron Microscopy images indicate a distribution of noble metal particles whose fraction less than 2 nm represents traces of Pt, at most 2% by weight of metal. The histogram of the fraction of particles larger than 2 nm in size is shown in the figure below. This histogram shows that particles with a size in the size range 13 + 6 nm

represent at least 70% of the number of particles.

Histogram of Pt particles on catalyst A z 4 - 2 - CDCD0 C 0ao O aO> 0 Size in A Example 2: Evaluation of catalyst Ai in hydroisomerization of a Fischer-Tropsch feed followed by separation and dewaxing catalytic The catalyst, the preparation of which is described in Example 1, is used in order to hydroisomerize a charge of paraffins obtained from the Fischer-Tropsch synthesis in order to obtain oils. In order to be able to use the hydroisomerization catalysts directly, the feed was hydrotreated beforehand and the oxygen content brought below 0.1% by weight. The main characteristics of the hydrotreated load are as follows: initial point 170 C 10% point 197 C 50% point 350 C 90% point 537 C end point 674 C fraction 380+ (% weight) 42 pour point + 73 C density (20/4) 0.787 The catalytic test unit comprises a fixed bed reactor, with up-flow of the feed ("up-flow"), into which 80 ml of catalyst is introduced. The catalyst is then subjected to an atmosphere of pure hydrogen at a pressure of 10 MPa in order to ensure the reduction of the platinum oxide to metallic platinum, then the feed is finally injected. The total pressure is 10 MPa, the hydrogen flow rate is 1000 liters of gaseous hydrogen per liter of feed injected, the hourly volume speed is 2 h "'and the reaction temperature is 350 C. After reaction, the effluents are fractionated into light products (gasoline Pl-150 C), middle distillates (150-380 C) and

residue (380 C).

The residue is then dewaxed in a second reactor with ascending flow of the feed ("up-flow"), into which is introduced 80 ml of catalyst containing 80% by weight of a Ferrierite zeolite of Si / Al ratio = 10.2 and 20% by weight of alumina as well as 0.6% by weight of Pt. The catalyst is then subjected to an atmosphere of pure hydrogen at a pressure of 10 MPa in order to ensure the reduction of the platinum oxide to metallic platinum then the load is finally injected. The total pressure is 10 MPa, the hydrogen flow rate is 1000 liters of gaseous hydrogen per liter of feed injected, the hourly volume speed is 1 h - 'and the reaction temperature is 350 C. After reaction, the effluents are divided into light products (petrol PI-150 C), distillates

medium (150-380 C) and residue (380 'C).

The characteristics of the oil obtained are measured.

The table below shows the yields for the various fractions and the characteristics of the oils obtained directly with the feed and with the effluents hydroisomerized on catalyst A1 (in accordance with the invention) then catalytically dewaxed. Load Catalytically paraffinized hydroisomerized and hydrotreated effluent Catalyst A1 Solvent waxing -20 C * catalytically dewaxed _______ _ according to the example Density of effluents at 15 C 0.790 0.779% weight 380 / effluents 58 69% weight 380 + / effluents 42 31 Quality of residue 380 'Dewaxing yield 6 59 (% by weight) Oil yield / feed 2.5 18.3 Oil quality VI (Viscosity index) | 143 140 Breakdown by cuts

PI-150 0 12

-380 58 57

* 380 '42 31

Net conversion to 380 '(%) 26.2

* the solvent used is methyl isobutyl ketone.

It is noted, very clearly, that the feed not hydroisomerized and dewaxed in solvent at -20 C, exhibits an extremely low oil yield while after the hydroisomerization and catalytic dewaxing operation, the oil yield

is higher.

Example 3: Evaluation of catalyst A1 during a test carried out for

I (produce middle distillates.

The operation is carried out in the same way as in Example 2, on the same load, but the operating conditions on the first reactor containing catalyst A1 are modified. The total pressure is 9 MPa, the hydrogen flow rate is 1000 liters of gaseous hydrogen per liter of injected feed, the hourly volume speed is 1 h - 'and the reaction temperature is 355 C. After reaction, the effluents are split into light products (gasoline Pl-150 C), kerosene (150-250 C), diesel (250- 380 C) and

residue (380 *).

The yields and characteristics for the different fractions of the hydroisomerized effluents on catalyst A1 are given below. Distribution by cuts: (% weight)

PI - 150 C: 18

- 250 C: 29

250 - 380 C: 43

380: 10

Quality of distillate products: - 250 C Smoke point: 48 mm Freezing point: - 31 C 250 - 380 C Cetane number: 62 Pour point: - 20 C Catalyst A1 provides good yields of middle distillates (fraction weight 150-250 C + fraction weight 250-380 C = 72% weight) from a charge of paraffins obtained from the Fischer-Tropsch synthesis and the middle distillates obtained

are of very good quality.

Claims (16)

1. Process for the production of oils from a hydrocarbon feed said process comprising the following successive steps: (a) conversion of the feed with simultaneous hydroisomerization of the n-paraffins of the feed, said feed having a sulfur content less than 1000 ppm by weight, a nitrogen content less than 200 ppm by weight, a metal content less than 50 ppm by weight, an oxygen content of at most 0.2% by weight, said step taking place at a temperature of 200- 500 C, under a pressure of 5 - 25 MPa, with a space speed of 0.1 - 5 h ', in the presence of hydrogen, and in the presence of a catalyst containing at least one noble metal deposited on an amorphous acidic support, the noble metal dispersion is less than 20%, (b) catalytic dewaxing of at least part of the effluent from step (a), carried out at a temperature of 200 - 500 C, under a pressure of 1 -25 Mpa, with an hourly volume speed of 0.05-50h-1, in the presence of 50-2000 liter of hydrogen / liter effluent entering step b and in the presence of a catalyst comprising at least one hydro-dehydrogenating element and at minus a molecular sieve. 2. The method of claim 1 wherein all of the effluent from step (a) is treated in step (b). 3. The method of claim 1 wherein the effluent from step (a) is distilled so as to separate the light gases and at least one residue containing the compounds with a boiling point greater than at least 340 C, said residue being submitted to step (b). 4. Method according to one of the preceding claims wherein the effluent from step (b) is distilled so as to separate an oil containing the compounds to boiling point greater than at least 340 C. 5. The method of claim 4 comprising atmospheric distillation followed by vacuum distillation of the atmospheric residue. 6. Method according to one of the preceding claims wherein the load subjected to step (a) has previously undergone a hydrotreatment and then optionally separation of water, ammonia and hydrogen sulfide. 7. Method according to one of the preceding claims characterized in that in the catalyst of step (a) the fraction of noble metal particles having a size less than 2 nm represents at most 2% by weight of the noble metal deposited on the catalyst. 8. Method according to one of the preceding claims characterized in that in the catalyst of step (a) at least 70% of the noble metal particles have a size greater than 4 nm. 9. Method according to one of the preceding claims characterized in that the support is chosen from the group formed by a silica-alumina, a halogenated alumina, an alumina doped with silicon, a mixture of titanium aluminaoxide, a sulfated zirconia, a zirconia doped with tungsten, alone or as a mixture. 10. The method of claim 9 characterized in that the support further comprises at least one amorphous matrix chosen from the group formed by alumina, titanium oxide, silica, boron oxide, magnesia, zirconia, clay. 11. Method according to one of the preceding claims characterized in that the support consists of an amorphous silica-alumina. 12. Catalyst according to one of the preceding claims characterized in that the support contains 1 - 95% by weight of silica and the catalyst 0.05 - 10% by weight of noble metal. 13. Method according to one of the preceding claims characterized in that the noble metal of the catalyst of step (a) and the hydro-dehydrogenating metal of the catalyst of step (b) are selected from the group formed by platinum and palladium. 14. Method according to one of the preceding claims, wherein the catalyst of step (b) comprises at least one molecular sieve, the microporous system of which has at least one main type of channels with pore openings having 9 or T atoms. T being chosen from the group formed by Si, Al, P, B, Ti, Fe, Ga, alternating with an equal number of oxygen atoms, the distance between two pore openings accessible to 9 or 10 T atoms being at most 0.75 nm, and said sieve exhibiting in the n-decane test a ratio 2-methylnonane / 5- methylnonane greater than 5. 15. The method of claim 14 wherein the sieve is a selected zeolite in the group formed by Nu-10, EU-1, EU-13, ferrierite, ZSM-22, theta-1, ZSM- 50, ZSM-23, Nu-23, ZSM-35, ZSM-38, IS1I-1, KZ-2, ISI-4, KZ-1. 16. Method according to one of the preceding claims wherein the effluent from step (b) is subjected to a hydrofinishing step before being distilled.