NL1015036C2 - Flexible process for the production of base oils and average distillation products with a conversion hydroisomerization followed by a catalytic dewaxing. - Google Patents

Abstract

In the present invention, there is disclosed a process for preparing oils from hydrocarbon feedstock comprising the following steps of: (a) conversion of the feedstock with simultaneous hydroisomerization of at least a portion of n-paraffins from the feedstock wherein said feedstock contains less than 1000 ppm of sulfur, less than 200 ppm of nitrogen, less than 50 ppm of metals and no more than 0.2 percent of oxygen, wherein the conversion step is carried out at a temperature ranging from 200 to 500 degC, at a pressure of 2 to 25 MPa and space velocity in the range of 0.1-10 he1, in the presence of hydrogen and a catalyst containing at least one noble metal deposited on an amorphous silicate-aluminium support; and (b) catalytic deparaffination of part (preferably all) of the effluent from the step (a) carried out at a temperature ranging from 200 to 500 degC, at a pressure of 1 to 25 MPa and a space velocity in the range of 0.05 to 50 he1 in the presence of hydrogen whose concentration ranges within 50 to 2000 l of hydrogen per 1 liter of effluent from the step (a) and in the presence of a catalyst comprising at least one hydro-dehydrogenating element and at least one molecular sieve.

Description

A00-30030 / TK / AGR

Short designation: Flexible process for the production of base oils and average distillation products with a conversion hydroisomerization followed by a catalytic dewaxing.

The present invention relates to an improved process for the production of very high quality base oils, i.e. having a high viscosity index (VI), good UV stability and a low pour point, starting from 5 hydrocarbon feeds (and preferably starting from from feeds derived from the Fischer-Tropsch process or from hydrocracking residues) with the possible simultaneous production of very high-quality medium distillation products (gas oils, kerosene for example), i.e. those with a low pour point and a high have cetane number.

State of the art

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

These lubricants are usually obtained by a succession of refining steps that allow the improvement of the properties of a petroleum fraction. In particular, treatment of the heavy petroleum fractions with large amounts of linear or slightly branched paraffins is necessary to obtain base oils of good quality and with the best possible yields, according to an operation which aims to remove linear or very slightly branched paraffins from batches which are then used as base oils.

Namely, the high molecular weight alkanes which are linear or very little branched and which are present in the oils lead to high pour points and thus to clotting phenomena for the low temperature applications. In order to reduce the values of the pour points 30, these linear alkanes, which are not or very little branched, must be completely or partially removed.

1015036 * -2-

Another agent is the catalytic treatment in the presence or absence of hydrogen and, taking into account their shape selectivity, the zeolites are among the most widely 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 catalysts currently used in the hydroisomerization are of the bifunctional type which combine an acid function with a hydrogenation function. The acid function is achieved by high surface area carriers (150 to 800 ng .g "1 in general) which have a surface acidity, such as the halogenated (especially chlorinated or fluorinated) aluminum oxides, the phosphorus containing aluminum oxides, the combinations of boron and aluminum oxides, the amorphous silicon alumina and the silica alumina The hydrogenation function is obtained either with one or more Group VIII metals of the Periodic Table of the Elements, such as iron, cobalt, nickel, ruthenium, rhodium, palladium, osmium, iridium and platinum, or by a compound of at least one Group VI metal such as chromium, molybdenum and tungsten and at least one Group VIII metal.

The balance between the two acidic and hydrogenating functions is the basic parameter that controls the activity and selectivity of the catalyst. A low acid function and strong hydrogenation function give catalysts which are less effective and selective for the isomerization, while a strong acid function and a low hydrogenation function give catalysts which are very active and selective for cracking. A third possibility is to use a strong acid function and a strong hydrogenating function to obtain a catalyst which is very effective but also very selective for the isomerization. It is therefore possible, by carefully selecting each of the functions, to match the activity / selectivity torque of the catalyst.

Applicant therefore proposes, according to the method described in the invention, to simultaneously produce average distillation products of very good quality, and base oils with VI and 1015036y -3 pour point at least equal to those obtained with a hydrorefining and / or or hydrocracking process.

Object of the invention 5

The applicant has focused its research efforts on applying an improved process for the production of very high quality lubricating oils and high quality average distillation products from hydrocarbon feeds 10 and preferably from hydrocarbon feeds derived from the Fischer-Tropsch process or starting from hydrocracking residues.

The present invention therefore relates to a series of processes for the joint production of very high quality base oils and very high quality average distillation products (in particular gas oils) starting from petroleum fractions. The oils obtained have a high viscosity index (VI), low volatility, good UV stability and a low pour point.

More particularly, the invention relates to a process for the production of oils from a hydrocarbon feed (of which at least 20% by volume has a boiling temperature of at least 340 ° C), which process comprises the following successive steps comprises: (a) conversion of the feed with simultaneous hydroisomerization of at least a portion of the n-alkanes of the feed, the feed having a sulfur content of less than 1000 wppm, a nitrogen content of less than 200 wt. ppm, having a metal content of less than 50 ppm by weight, having an oxygen content of at most 0.2%, this step being carried out at a temperature of 200-500 ° C, under a pressure of 2-25 MPa, with a spatial rate of 0.1-10 hr -1, in the presence of hydrogen in an amount generally ranging from 100-2000 liters of hydrogen / liter of feed and in the presence of a catalyst depositing at least one precious metal on a 10 1 503 6 ^ -4-amorphous acidic carrier, the noble metal dispersion being between 20-100%.

(b) catalytic dewaxing of at least a portion of the effluent from step a) conducted at a temperature of 200-500 ° C, under a pressure of 1-25 MPa, at a volume parts per hour rate of 0.05-50 hours, in the presence of 50-2000 liters 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 hydrogen treatment step which is generally carried out at a temperature of 200-450 ° C, under a pressure of 2 to 25 MPa, at a spatial speed of 0.1- 6 hours, in the presence of hydrogen in a hydrogen / hydrocarbon volume ratio of 100-2000 liters / liter, and in the presence of an amorphous catalyst containing at least one Group VIII metal and at least one Group VIB metal.

The entire effluent from step (a) can be fed into step (b). Step (a) may optionally be followed by a separation of the light gaseous compounds from the effluent obtained at the exit of step (a).

Preferably, the effluent from the conversion hydroisomerization treatment (a) is subjected to a distillation step (preferably atmospheric) to form the compounds having a boiling point below 340 ° C (gas, gasoline, kerosene, gas oil ) from the products with an initial boiling point greater than at least 340 ° C and which form the residue. It is thus generally separated at least an average distillate fraction having a pour point of at most -20 ° C and a cetane index of at least 50.

The catalytic dewaxing step (b) is therefore applied to at least the residue from the distillation, which contains compounds having a boiling point higher than at least 340 ° C. In another embodiment of the invention, the effluent from step (a) is not distilled 101 503 6 "-5- before being subjected to step (b). At the most it is subjected to a separation of at least a part of the light gases (by flash evaporation ...) and is then subjected to the catalytic dewaxing.

Preferably, step (b) is carried out with a catalyst containing at least one molecular sieve whose microporous system has at least one main type of channels with pore openings having 9 or 10 atoms T, T being selected from the group consisting of Si / Al, P, B, Ti, Fe, Ga, interspersed with an equal number of oxygen atoms, the distance between two openings of the accessible pores comprising up to 9 or 10 atoms T being at most equal is at 0.75 mm, and wherein the sieve in the n-decane test has a 2-methylnonane / 5-methylnonane ratio greater than 5.

Advantageously, the effluent from the dewaxing treatment is subjected to a distillation step which advantageously comprises atmospheric distillation and a distillation under vacuum to separate at least an oil fraction having a boiling point greater than at least 340 ° C. It usually has a pour point of less than -10 ° C and a VI greater than 95, a viscosity at 100 ° C of at least 3 cST (or 3 mm2 / s). This distillation step is essential when there is no distillation between steps (a) and (b).

Advantageously, the effluent from the dewaxing treatment, which may have been distilled, is subjected to a final treatment with hydrogen (hydrofinishing).

Detailed description of the invention The method according to the invention comprises the following steps:

The nutrition;

The hydrocarbon feed from which the oils and optionally the average high quality distillation products are obtained preferably contains at least 20% by volume of compounds boiling above 340 ° C, preferably at least 350 ° C and advantageously at least 380 ° C . This does not mean that the boiling point is 380 ° C and above, but 380 ° C or above.

101503 6ί -6-

The food contains n-alkanes. Preferably, the feed is an effluent from a Fischer-Tropsch unit. Very varied feeds can be treated with the method.

The feed may also consist, for example, of vacuum distillation products from the direct distillation of the unrefined product or from conversion units such as the FCC, the coke factory or the viscosity reduction device, or from aromatic extraction units. compounds, either from the hydrogen treatment or hydrogen reaction of RAT (atmospheric residues) and / or RSV (vacuum residues), or the feed may also be a de-asphalted oil, or also a hydrocracking residue, eg from DSV or any mixture of the aforementioned feedings. The above list is not exhaustive.

Generally, the power supplies intended for oils have an initial boiling point greater than at least 340 ° C and even better greater than at least 370 ° C.

The feed fed in step (a) for the conversion hydroisomerization must be suitable. By suitable feed we mean the feed whose sulfur content is less than 1000 wppm and preferably less than 50 wppm and even more preferably less than 300 wppm or better than 100 wppm. The nitrogen content is less than 200 wppm and preferably less than 100 wppm and even more preferably less than 50 wppm. The metal content of the feed such as nickel and vanadium is particularly low, ie less than 50 wppm and advantageously less than 10 wppm, or better than 2 wppm.

When the amounts of unsaturated or oxygen containing products can lead to a very important deactivation of the catalytic system, the feed (for example from the Fischer-Tropsch process) will be subjected before it is fed to the hydroisomerization zone. to a hydrogen treatment in a hydrogen treatment zone. The hydrogen is reacted with the feed in contact with a hydrotreating catalyst whose function is to reduce the content of unsaturated and oxygen-containing hydrocarbon molecules (for example, formed during the Fischer-101 503 6 ^ -7-

Tropsch synthesis). The oxygen content is thus reduced to a maximum of 0.2% by weight.

When the feed to be treated is unsuitable in the above sense, it is subjected to a preliminary hydrogen treatment step for a first period, in which, in the presence of hydrogen, it is contacted with at least one catalyst containing an amorphous carrier and at least one metal which has a hydro-dehydrogenating effect, which is ensured, for example, by at least one group VIB element 10 and at least one group VIII element, at a temperature between 200 and 450 ° C, preferably 250- 450 ° C, advantageously 330-450 ° C or 360-420 ° C, under a pressure between 5 and 25 MPa or better than 20 MPa, preferably between 5 and 20 MPa, the spatial speed being between 0.1 and 66 hours -1, preferably 0.3-3 hours -1, and the amount of hydrogen supplied is such that the volume ratio of hydrogen / hydrocarbon is between 100 and 2000 liters / liter.

The support is generally based (preferably consists predominantly of) amorphous alumina or silica-alumina; it may also contain boron oxide, magnesium oxide, zirconium oxide, titanium oxide or a combination of these oxides. The hydro-dehydrogenating action is preferably fulfilled by at least one metal or compound of a Group VIII and VIB metal, preferably selected from molybdenum, tungsten, nickel and cobalt.

This catalyst may advantageously contain phosphorus; Namely, it is known in the art that the compound gives two advantages to hydrotreating catalysts: easy preparation during especially impregnation of the nickel and molybdenum solutions, and better hydrogenation activity.

The preferred catalysts are the NiMo and / or NiW on alumina catalysts, also the NiMo and / or NiW on alumina catalysts doped with at least one element from the group of atoms formed by phosphorus, boron, silicon and fluorine, or also the catalysts NiMo and / or NiW on silica-alumina, or on silica-alumina-titanium oxide, doped or not doped with at least one element of the group of atoms, consisting of at least 10 1 50 36 -8 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 in metal oxide between metal (or metals) from group VI to metal (or metals) Group VIII) is preferably between 20 and 1.25 and even more preferably between 10 and 2. The concentration of phosphorus oxide P2 O5 will be less than 15% by weight and preferably less than 10% by weight.

Before feeding in step (a), the product obtained after the hydrotreatment is subjected, if necessary, to an intermediate separation of water (H 2 O, H 2 S, NH 3) to determine the content of water, H 2 S and NH 3 in the feed which is fed to step (a) to values which are respectively less than at most 100 ppm, 200 ppm, 50 ppm. At this point, a possible separation of the products with a boiling point below 340 ° C can be considered to treat only one residue in step (a).

When a hydrocracking residue is treated, a feed which has already been treated with hydrogen and a hydrocracking is treated. The appropriate feed can then be directly treated in step (a).

Hydrocracking generally takes place with a zeolite catalyst, usually based on zeolite Y, and in particular on desaluminated zeolites Y.

The catalyst also contains at least one Group VIII non-noble metal and at least one Group VIB metal.

Step (a): hydroisomerization conversion. The catalyst

Step (a) takes place in the presence of hydrogen and in the presence of a bifunctional catalyst comprising an amorphous acid support (preferably an amorphous silica-alumina) and a hydro-dehydrogenating metallic function guaranteed by at least one noble metal. The spread of precious metal is 20-100%.

101 5036 ï -9-

The support is called amorphous, i.e. without a molecular sieve, and in particular without a zeolite, as well as the catalyst. The amorphous acidic carrier is advantageously an amorphous silica-alumina, but other carriers can be used.

When it is a silica-alumina, the catalyst generally does not contain added halogen, except that which may have been supplied for impregnation, for example, the noble metal.

During this step, the n-alkanes in the presence of a bifunctional catalyst are subjected to an isomerization, then optionally hydrocracking, to form isoalkanes and much lighter cracking products such as the gas oils and kerosene, respectively. The conversion generally ranges between 5 and 90%, but is generally at least 20% or greater than 20%.

In a preferred embodiment of the invention, a catalyst is used which comprises a particular silica-alumina which makes it possible to obtain catalysts which are very effective but also very selective in the isomerization of feeds such as those described above.

A preferred catalyst comprises (and preferably mainly consists of) 0.05-10 wt% of at least one Group VIII noble metal supported on an amorphous silica-alumina support (which preferably contains 5-70 wt% silica) ) which has a specific surface area BET of 100-500 m2 / g and has the catalyst 25: an average diameter of the mesopores between 1-12 nm, a pore volume of the pores whose diameter lies between the average diameter as described previously, minus 3 nm and the mean diameter, as previously described, plus 3 nm, greater than 40% of the total pore volume, a distribution of the precious metal between 20-100%, a distribution coefficient of the precious metal greater than 0, 1.

The properties of the catalyst according to the invention are in particular: 101503 6 ^ -10-

Silica content: The support which is preferably used for the preparation of the catalyst described under this patent consists of SiO 2 silica and Al 2 O 3 alumina. The silicon oxide content of the support, expressed in weight percent, is generally between 1 and 95%, advantageously between 5 and 95%, and more preferably between 10 and 80%, and even more preferably between 20 and 70. % and between 22 and 75%. This silicon oxide content is best measured by X-ray fluorescence.

10

Nature of the precious metal: For this particular type of reaction, the metal function is obtained with a Group VIII noble metal of the periodic table of the elements and more particularly platinum and / or palladium.

15

Precious metal content: The precious metal content, expressed in weight percent of the metal relative to the catalyst, is between 0.05 and 10, more preferably between 0.1 and 5.

20 Distribution of the precious metal; the dispersion representing the metal fraction accessible to the reagent relative to the total amount of the metal of the catalyst can be measured, for example, by H 2/02 titration. The metal is pre-reduced, ie it is subjected to a treatment under a stream of hydrogen at a high temperature under conditions such that the platinum atoms accessible to hydrogen are converted to the metal form. Thereafter, a stream of oxygen is supplied under suitable operating conditions so that all the reduced platinum atoms accessible to oxygen are oxidized in the PtO2 form. By calculating the difference between the amount of oxygen supplied and the amount of oxygen that flows out, the amount of oxygen consumed is obtained; it is thus possible to derive the amount of platinum accessible to oxygen from the latter value.

The dispersion is then equal to the ratio of the oxygen-accessible amount of platinum to the total amount of platinum of the catalyst. In our case, the spread is between 20% and 100% and preferably between 30% and 100%.

10 1 503 6-1 -11-

Noble Metal Distribution: The noble metal distribution represents the dispersion of the metal in the catalyst grain, where the metal may be well or poorly dispersed. Thus it is possible to obtain poorly distributed platinum (for example observed in a crown the thickness of which is clearly less than the radius of the grain), but well distributed, ie all platinum atoms placed in the crown are accessible for the reagents. In our case, the distribution of platinum is good, ie the profile of the platinum, measured by the Castaing microprobe method, has a distribution coefficient greater than 0.1 and preferably greater than 0.2.

BET surface: the BET surface of the support is between 100 m2 / g 15 and 500 m2 / g and preferably between 250 m2 / g and 450 m2 / g and for the supports based on alumina, more preferably between 310 m2 / g and 450 m2 / g.

Average Pore Diameter: For the preferred catalysts, based on silica-alumina, the average diameter of the catalyst pores is measured from the pore distribution profile obtained using a mercury porosimeter. The average diameter of the pores is determined as the diameter corresponding to the elimination of the derivative curve obtained from the mercury porosity curve. The average diameter of the pores, thus determined, is between 1 nm (lxlO'9 meters) and 12 nm (12x10 "9 meters) and preferably between 1 nm (lxl0 ~ 9 meters) and 11 nm (11x10" 9 meters). and even more preferably between 3 nm (4x109 meters) and 10.5 nm (10.5x109 meters).

30

Pore distribution: The preferred catalyst referred to in this patent has a pore distribution such that the porous volume of the pores whose diameter is between the average diameter, as previously determined, less 3 nm and the average diameter as previously determined, enlarged by 3 nm (or the mean diameter ± 3 nm) is greater than 40% of the total pore volume and preferably is between 50% and 90% of the 1015036 -12 total pore volume and with still more advantage between 50% and 70% of the total pore volume.

Global pore volume of the support: for the catalyst, which is preferably based on silica-alumina, it is generally less than 1.0 ml / g and is preferably between 0.3 and 0.9 ml / g and with even more advantage less than 0.85 ml / g.

The preparation and shaping of the support, and in particular of silica-alumina (especially used in the preferred embodiment), takes place according to conventional methods known to the person skilled in the art. Advantageously, prior to impregnating the metal, the support can be subjected to a calcination such as, for example, a heat treatment at 300-750 ° C (preferably 600eC) for 0.25-10 hours (preferably 2 hours) under 0-30% by volume water vapor (for the silica-alumina preferably 7.5%).

The precious metal salt is fed by any of the conventional methods used to deposit the metal (preferably platinum and / or palladium, even more preferred platinum) on the surface of a support. One of the preferred methods is dry impregnation, which consists of feeding the metal salt in an amount of solution equal to the pore volume of the catalyst mass to be impregnated. To effect the reduction, the catalyst can be subjected to a calcination such as, for example, a dry air treatment at 300-750 ° C (preferably 520 ° C) for 0.25-20 hours (preferably 2 hours).

Before use in the hydroisomerization conversion reaction, the metal present in the catalyst must be reduced. One of the preferred methods for carrying out the reduction of the metal is the treatment under hydrogen at a temperature between 150 ° C and 650 ° C and a total pressure between 0.1 and 25 MPa. For example, a reduction consists of a flat path at 150 ° C for 2 hours, then a temperature rise to 450 ° C at a rate of 1 ° C / min, then a flat path for 2 hours at 450 ° C; wherein during the entire reduction step the hydrogen flow rate is 1000 1015036 * -13-liter hydrogen / liter catalyst. It is also noted that any ex-situ reduction method is suitable.

The operating conditions under which this step (a) is performed are important.

5 The pressure will generally be maintained between 2 and 25 MPa (usually at least 5 MPa) and preferably 2 (or 3) to 20 MPa and suitably from 2 to 18 MPa, the spatial velocity will usually be between 0.1 hours' 1 and 10 hours' 1 and preferably between 0.2 and 10 hours' 1 and expediently between 0.1 or 0.5 hours' 1 and 5.0 hours' 1, and the hydrogen content is generally between 100 and 2000 liters of hydrogen per liter of food and preferably between 150 and 1500 liters of hydrogen per liter of food.

The temperature used in this step is usually between 200 and 500 ° C (or 450 ° C) and preferably from 250 ° C to 450 ° C, advantageously from 300 to 450 ° C, and even more efficiently above 340 ° C, for example between 320-450 ° C.

The two steps of hydrogen treatment and hydro-isomerization conversion can be carried out with the two kinds of catalysts in (two or more) different reactors, or / and on at least two catalytic beds placed in the same reactor.

As shown in U.S. Patent No. 5,879,539, the use of the catalyst described below in step (a) has the effect of increasing the viscosity index (VI) by +10 points. More generally, it is observed that the magnification of the VI is at least 2 points, the VI being measured with a feed (residue) dewaxed with solvent and with the product from step (a) which is also solvent has been dewaxed to obtain a temperature of pour point 30 between -15 and -20 ° C.

Generally, an increase in the VI of at least 5 points is obtained, and usually more than 5 points, for example more than 10 points.

It is possible to control the magnification of the VI especially based on the degree of conversion. It will thus be possible to optimize production for oils with high VI or for much higher oil yields but with less higher VI.

1015036- -14-

In addition to the magnification of the VI, a pour point decrease is usually obtained which can range from a few degrees to 10-15 ° C as above (e.g. 25 ° C). The magnitude of the decrease varies as a function of the conversion and therefore of the operating conditions and of the feed.

Treatment of the effluent from step (a) In a preferred embodiment, the effluent from step (a) of the hydroisomerization conversion as a whole can be treated in the dewaxing step (b). In a variant, it can be subjected to a separation of a portion of at least (and preferably at least a major portion) of the light gases comprising hydrogen and optionally also hydrocarbon compounds with up to 4 carbon atoms. The hydrogen can be separated beforehand. The embodiment (excluded variant), with passage in stage (b) of the entire effluent from stage (a), is economically interesting because a single distillation unit is used at the end of the process. In addition, in the final distillation (after catalytic dewaxing or later treatments) a gas oil suitable for strong cold is obtained.

Advantageously, in another embodiment, the effluent from step 25 (a) is distilled to separate the light gases and also separate at least one residue containing the compounds having a boiling point higher than at least 340 ° C. It is preferably atmospheric distillation.

It is advantageous to distill to obtain different 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 greater than at least 340 ° C and better greater than 350 ° C and preferably at least 370 ° C or 380 ° C.

According to a preferred variant of the invention, this fraction (residue) will then be treated in the catalytic dewaxing step, i.e. without being subjected to the vacuum distillation. In another variant, however, one can use a vacuum distillation.

1015036 * -15-

In an embodiment more focused on the production of average distillation products, and still according to the invention, it is possible to return part of the residue from the separation step to the reactor 5 containing the hydroisomerization catalyst to converting it and increasing the production of average distillation products.

Generally in this text, average distillation products are referred to as the fraction (s) with initial boiling point of at least 150 ° C and which finally go to the residue, i.e. generally 10 to 340 ° C, 350 ° C or preferably lower than 370 ° C or 380 ° C.

The effluent from step (a) may, before or after distillation, be subjected to other treatments, such as, for example, an extraction of a portion of at least the aromatics.

15

Step (b): catalytic dewaxing with hydrogen

A portion of at least the effluent from step (a), with the effluent optionally subjected to the separations and / or treatments described above, is then subjected to a catalytic dewaxing step in the presence of hydrogen and a dewaxing catalyst. with hydrogen comprising an acidic function, a hydro-dehydrogenating metallic function and at least one matrix.

It is noted that the compounds boiling above at least 340 ° C are always subjected to catalytic dewaxing.

The catalyst. The acidic function is ensured with at least one molecular sieve and preferably a molecular sieve whose microporous system has at least one major type of channels whose openings are formed of rings containing 10 or 9 T atoms. The atoms T are tetrahedral atoms that form the molecular sieve and can be at least one of the elements present in the following system of atoms (Si, Al, P, B, Ti, Fe, Ga). In the constituent rings of the channel openings, the atoms T previously determined are alternated with the same number of 1015036 * 16 oxygen atoms. It can therefore also be said that the openings are formed from rings containing 10 or 9 oxygen atoms or formed from rings containing 10 or 9 T atoms.

The molecular sieve contained in the hydrogen dewaxing catalyst composition may also contain other types of channels, but the apertures are formed of rings containing less than 10 T atoms or oxygen atoms.

The molecular sieve present in the composition of the preferred catalyst additionally has a bridging quantity, distance between two pore openings, as previously described, which is at most 0.75 nm (1 nm = 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 allow to obtain good catalytic yields in the hydrogen dewaxing step.

The bridging quantity is measured using a graphical and molecular modeling tool such as Hyperchem or Biosym, which allows to construct the area of 20 molecular sieves concerned and taking into account ion beams of the elements present in the lattice of the sieve, to measure the bridge quantity.

The preferred catalyst suitable for this process can also be characterized by a catalytic test called standard test for the conversion of pure n-decane performed under a hydrogen partial pressure of 450 kPa and a n-C10 partial pressure of 1 , 2 kPa or a total pressure of 451.2 kPa in a fixed bed and with a constant flow rate of n-C10 of 9,5 ml / h, a total flow rate of 3.6 l / h and a catalyst mass of 0, 2 g. The reaction is run in a downward flow. The conversion number is controlled by the temperature at which the reaction takes place. The catalyst subjected to this test consisted of pure zeolite in the form of tablets and 0.5% by weight of platinum.

N-decane in the presence of the molecular sieve and having a hydro-dehydrogenating action is subjected to hydro-isomerization reactions that will form isomerized products with 10 carbon atoms, and hydrocracking reactions that lead to to the formation of products containing less than 10 carbon atoms.

Under these conditions, a molecular sieve used in the hydrogen dewaxing stage with the preferred catalyst of the invention must have and direct the above-described physicochemical properties for an isomerized n-CIO product yield of about 5 wt% ( the conversion number is controlled by the temperature), to a ratio of 2-methylnonane / 5-methylnonane which is greater than 5 and preferably greater than 7.

The use of molecular sieves thus selected, under the conditions described above, from the numerous pre-existing molecular sieves, in particular allows production of low pour point and high viscosity index products with good yields in the context of the process of the invention.

The molecular sieves which may be present in the preferred catalyst composition for catalytic dewaxing with hydrogen are, for example, the following zeolites: ferrierite, NU-10, EU-13, EU-1. Preferably, the molecular sieves present in the hydrogen dewaxing catalyst composition are present in the system formed by ferrierite and zeolite EU-1.

In general, the hydrogen dewaxing catalyst comprises a zeolite selected from the group consisting of NU-10, EU-1, EU-13, ferrierite, ZSM-22, Theta-1, ZSM-50, ZSM -23, NU-23, ZSM-35, ZSM-38, ZSM-48, ISI-1, KZ-2, ISI-4, KZ-1.

The weight amount of molecular sieve in the hydrogen dewaxing catalyst is between 1 and 90%, preferably between 5 and 90%, and even more preferably between 10 and 85%.

The matrices used to form the catalyst are exemplary and non-limiting, the alumina gels, the alumina, magnesia, the amorphous silica-alumina, and their mixtures. Techniques such as extrusion, tabletting or dragee making can be used to perform the molding.

The catalyst also includes a hydro-dehydrogenating function, which is assured, for example, by at least one Group VIII 1015 θ 36--18 element and preferably at least one noble group element consisting of platinum and palladium. The weight content of Group VIII non-noble metal, relative to the final catalyst, is between 1 and 40%, preferably between 10 and 30%. In this case, the non-noble metal is usually bonded to at least one group VIB metal (preferably Mo and W). With respect to at least one Group VIII noble metal, the weight content, relative to the final catalyst, is less than 5%, preferably less than 3%, and even more preferably less than 1.5%.

When using Group VIII noble metals, platinum and / or palladium are preferably applied to the matrix.

The hydrogen dewaxing catalyst of the invention may further contain 0 to 20 wt%, preferably 0 to 10 wt% (expressed as oxides) of phosphorus. The combination of Group VIB metal (s) and / or Group VIII metal (s) with phosphorus is particularly advantageous.

The treatment 20

A residue obtained at the end of step (a) and of the distillation, which is important to treat in this step (b) of hydrogen dewaxing, has the following properties: 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), a content of aromatics of less than 10 wt%, a nitrogen content of less than 10 wtppm, a sulfur content of less than 50 wppm, or better than 10 wppm.

The operating conditions in which the catalytic step of the process according to the invention is carried out are the following: 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 (106 Pa) and preferably between 1.0 and 20 MPa; 1015038 ^ -19- the rate per volume part per hour (wh, expressed in volume of the injected feed per unit of catalyst volume and per hour) is between about 0.05 and about 50, and preferably between about 0.1 and about 20 hours 1 and even more preferably between 0.2 and 10 o'clock.

They are chosen to obtain the desired pour point.

The contact between the feed and the catalyst is carried out in the presence of hydrogen. The hydrogen content used and expressed in liters of hydrogen per liter of feed is between 50 and about 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 end of step (b) of dewaxing with hydrogen is fed into the distillation chain, which preferably comprises atmospheric distillation and a distillation under vacuum, which serves to convert the reaction products with a boiling point below 340 ° C and preferably separating below 370eC (and especially comprising those formed during the catalytic step of dewaxing with hydrogen), and separating the fraction forming the base oil having an initial boiling point greater than at least 340 ° C and preferably greater than or equal to 370 ° C.

Incidentally, this part of the distillation under vacuum makes it possible to separate different qualities of oils.

Preferably, before distilling, the effluent is passed over a hydro-finishing (hydrogen finish) catalyst in the presence of hydrogen (at least in part and preferably in its entirety) after step (b) of the catalytic dewaxing with hydrogen. of hydrogen to perform a vigorous hydrogenation of the aromatic compounds which are detrimental to the stability of oils and distillation products. However, the acidity of the catalyst must be low enough not to lead to the formation of cracking products having a boiling point below 340 ° C so as not to reduce the final yields, especially of oils.

The catalyst used in this step contains at least one Group VIII metal and / or and at least one Group VIB element

1015035 ^ -20- of the periodic table. The strong metal functions: platinum and / or palladium, or nickel-tungsten, nickel-molybdenum combinations are advantageously used to effect vigorous hydrogenation of the aromatics.

These metals are deposited and dispersed on an amorphous or crystalline oxide-type support such as, for example, the aluminum oxides, the silicon oxides, the silicon oxide-aluminum oxides.

The hydro-finishing catalyst (HDF) may also contain at least one element of Group VII A of the periodic table elements. These catalysts preferably contain fluorine and / or chlorine.

The weight content of metals is between 10 and 30% in the case of non-precious 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 the precious metals.

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

As catalysts which can be used in this hydrofinishing step and which lead to excellent yields, and in particular for obtaining medicinal oils, one can mention the catalysts which contain at least one Group VIII noble metal (platinum and VIII for example). and contain at least one halogen (chlorine and / or fluorine), the combination of chlorine and fluorine being preferred.

The operating conditions under which the hydro-finishing step of the process according to the invention is carried out are the following: 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 20 MPa; the volume rate per hour (wh, expressed in volume parts of the injected feed per unit volume of the catalyst and per hour) is between about 0.05 and about 100, and preferably between about 0.1 and about 30 hours. 1.

1 0 1 u ü o c ί -21-

The contact between the feed and the catalyst is carried out in the presence of hydrogen. The hydrogen content, which is used and expressed in liters of hydrogen per liter of feed, is between 50 and about 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 hydro-finishing stage (HDF) is lower than the temperature of the catalytic dewaxing stage with hydrogen (HDPC). The difference ThdpC-Thdf is generally between 20 and 200, and preferably between 30 and 100eC. The effluent at the end of HDF is then sent into the distillation chain.

The products. The base oils obtained by this method have a pour point less than -10 ° C, a VI 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 a stability against UV such that the increase of the ASTM color is between 0 and 4 and preferably between 0.5 and 2.5.

The UV stability test, suitable for the ASTM D925-55 and D1148-55 methods, provides a rapid method to compare the stability of lubricating oils exposed to a source of ultraviolet rays. The test chamber consists of a metal space 25 provided with a turntable which obtains the oil samples. An incandescent lamp that forms the same ultraviolet rays as that of the sunlight and is placed in the top of the test chamber is directed downwards on the samples. The samples include a standard oil with known U.V. characteristics. The ASTM D1500 color of the 30 samples was determined at t = 0, then after exposure at 55 ° C for 45 hours. The results were converted in the following manner for the standard sample and the test samples: a) initial color ASTM D1500, b) final color ASTM D1500, 35 c) increase in color, d) cloudy, e) precipitated.

1015036- -22-

Another advantage of the method according to the invention is that it is possible to obtain very low amounts of aromatic compounds (less than 2% by weight, preferably 1% by weight and more preferably less than 0.05% by weight) and even produce 5 pure medicinal grade oils having amounts of aromatics less than 0.01 wt%. These oils have UV absorption values at 275, 295 and 300 nanometers that are less than 0.8, 0.4 and 0.3 respectively (ASTM D2008 method) and a

Saybolt color that is between 0 and 30.

In a particularly interesting manner, the method according to the invention therefore also makes it possible to obtain pure medicinal oils. The pure medicinal oils are mineral oils obtained by vigorous refining of the petroleum, their quality is subject to various regiments aimed at guaranteeing their harmlessness for pharmaceutical applications, they have no toxicity and are characterized by their density and their viscosity. The pure medicinal oils mainly comprise saturated hydrocarbons, they are chemically inert and their aromatic hydrocarbon content is low. Particular importance is attached to aromatics and in particular to 6 polycyclic aromatic hydrocarbons (P.A.H. for the Anglo-Saxon abbreviation for polycyclic aromatic hydrocarbons) which are toxic and present in concentrations of one part by weight per billion of the aromatic compounds in the pure oil. The control of the total content of aromatics can be carried out according to the method ASTM D2008, this UV absorption test at 275, 292 and 300 nanometers allows to check a lower absorption at 0.8, 0.4 and 0.3 respectively (ie the pure oils have amounts of aromatics less than 0.01 wt%). These measurements are performed with concentrations of 1 g of oil per liter, in a 1 cm container. The pure oils marketed are different in their viscosity but also in their crude origin which may be paraffinic or naphthenic, these two parameters may give differences both in the physicochemical properties of the respective pure oils but also in their chemical composition .

1015036 * -23-

Currently, the oil fractions, which come either from the direct distillation of a crude oil followed by an extraction of the aromatics with a solvent, or from the catalytic hydrorefining or hydrocracking, still contain 5 negligible amounts of aromatics. In the current legislative framework of most industrial countries, the said medicinal pure oils must have a content of aromatic compounds below a threshold set by the legislation of each country. The absence of these 10 aromatic compounds in the oil fractions is evidenced by a specification of the Saybolt color which must be substantially at least 30 (+30), a maximum UV absorption specification which must be less than 1.60 at 275 nm for a pure product in a 1 cm well and a maximum absorption specification of the extraction products 15 with DMSO should be less than 0.1 for the US market (Food and Drug Administration, Standard No. 1211145). The latter test consists of extracting polycyclic aromatic hydrocarbons specifically using a polar solvent, usually DMSO, and checking their extract content with a UV absorption measurement in the range of 260-350 nm.

The invention will be illustrated with Figures 1 to 3, which illustrate various embodiments for the treatment of a feed, for example, from the Fischer-Tropsch process or from a hydrocracking residue.

25

Figure 1

In Figure 1, the feed enters via line (1) into a hydrotreating zone (2) (which may consist of one or more reactors, and may comprise one or more catalytic beds of one or more catalysts) in which the hydrogen flows in (e.g. via line (3)) and where the hydrotreating step is carried out.

The hydrotreated feed is transferred via line (4) to the hydroisomerization zone (7) (which may consist of one or more reactors and include one or more catalytic beds of one or more catalysts) where, in the presence of hydrogen, the 1n1503 6 * -24- hydroisomerization step (a) is performed. We hydrogen can be supplied through line (8).

In this figure, before the feed to be hydro-isorerized is fed into zone (7), it is freed from a large portion of its water in flask (5), the water draining off via line (6) and possibly ammonia and hydrogen sulphide H2S, when the feed entering through line 1 contains sulfur and nitrogen.

The effluent from zone (7) is fed through a line (9) into a hydrogen separation flask (10) which is withdrawn through line (11), the effluent is then distilled at atmospheric pressure in column (12) where in the top a line is withdrawn via line (13) containing the compounds with a maximum of 4 carbon atoms and those with a lower boiling point.

At least one gasoline fraction (14) and at least a fraction of an average distillation product (kerosene (15) and gas oil (16) for example) are also obtained.

A fraction containing the compounds having a boiling point higher than at least 340 ° C is obtained in the bottom of the column. This fraction is discharged via line (17) to zone (18) for catalytic dewaxing.

Catalytic de-paraffinization zone (comprising one or more reactors, one or more catalytic beds of one or more catalysts) also receives hydrogen via line (19) to perform step (b) of the process.

The resulting effluent flowing out through line (20) is separated into a distillation chain which, in addition to hydrogen separation flask (21) through line (22), includes an atmospheric distillation column (23) and a vacuum column (24) which line (25) treats transferred residue from the atmospheric distillation, which residue has an initial boiling point greater than 340 ° C.

At the end of the distillations, the products are obtained as an oil fraction (line 26) and lower boiling fractions, such as gas oil (line 27), kerosene (line 28), petrol (line 29); the light gases being removed through line (30) from the atmospheric column and through line (31) from the vacuum distillation column.

The effluent draining from line (20) can also advantageously be fed into a hydro-finishing zone (not shown 1015036 -25-) (comprising one or more reactors, one or more catalytic beds of one or more catalysts) before it is injected into the separation chain Hydrogen can be added in this zone if necessary The effluent that flows out is then transferred to a flask (21) and the described distillation chain.

In order not to burden the figure, the return of hydrogen, which takes place from the flask (10) to the treatment with hydrogen and / or hydroisomerization, and / or from the flask (21) to the dewaxing and / or is not shown. hydro-finishing.

10

Figure 2

It can be seen that the reference numerals of FIG. 1 have been repeated here. In this embodiment, the entire effluent from zone (7) of the hydroisomerization conversion (step a) goes directly through line (9) to catalytic dewaxing zone (step b).

Figure 3 20

In the same manner as above, the reference numerals of FIG. 1 are quoted. In this embodiment, the effluent from the hydroisomerization conversion zone (7) (step a) in flask (32) is separated from at least a portion of the light gases (hydrogen and hydrocarbon compounds with at most 4 carbon atoms), for example, by flash evaporation. The separated gases are withdrawn via line (33) and the residual effluent is fed via line (34) into the catalytic dewaxing zone (18).

It can be seen that in Figures 1, 2 and 3 a separation is provided for the effluent from zone (18) for the catalytic dewaxing. This separation cannot be performed if the effluent is later treated in a hydro-finishing zone, where the separation takes place or after this treatment.

35 This concerns the separation that is carried out in the flasks or columns 21, 23, 24.

1015036 ^ -26-

Example 1: Preparation of catalyst A1 according to the invention

Catalyst A1 is prepared from a silica-alumina support which is used in the form of extruded particles. It contains 29.3 wt.% SiO 2 silica and 70.7 wt.% Alumina Al 2 O 3. The silica-alumina, before noble metal addition, has a surface area of 330 m2 / g and its total pore volume is 0.87 ml / g.

Catalyst Al is obtained after impregnating the precious metal on the support. Platinum salt H2PtCl6 is dissolved in an amount of solution corresponding to the total pore volume to be impregnated. The solid is then calcined for 2 hours under dry air at 500 ° C. The platinum content is 0.60% by weight. Measured with the catalyst, the BET surface area is 312 m2 / g. The platinum spread measured by H2 / 02 titration is 99%. It is difficult to detect platinum with transmission electron microscopy. When visualized, it is present as very small particles from 0.7 to 1.0 nm.

Example 2: Evaluation of catalyst Al in the hydroisomerization of a Fischer-Tropsch feed followed by a separation and catalytic dewaxing

The catalyst the preparation of which is described in Example 1 is used to hydroisomerize a feed of alkanes from the Fischer-Tropsch synthesis to obtain oils. To directly use the hydroisomerization catalysts, the feed was previously hydrotreated and the oxygen content adjusted to less than 0.1% by weight. The main properties of the hydrotreated feed 30 are as follows:

starting point 170 ° C

point 10% 197 ° C

point 50% 350eC

35 point 90% 537 ° C

end point 674 ° C

fraction 380+ (wt%) 42

pour point + 73 ° C

1015036 * -27- density (20/4) 0.787

The catalytic test unit includes a fixed bed reactor, with increasing feed circulation ("up-flow"), into which 80 ml of catalyst are introduced. The catalyst is then subjected to an atmosphere of pure hydrogen at a pressure of 10 MPa to ensure the reduction of the platinum oxide to metallic platinum, after which the feed is finally injected. The total pressure is 10 MPa, the hydrogen flow rate is 1000 liters of gaseous hydrogen per liter of injected feed, the rate per volume part per hour is 2 hours and the reaction temperature is 350 ° C. After the reaction, the effluents are fractionated into light products (gasoline PI-150 ° C), medium distillation products (150-380 ° C) and residue (380 * ° C).

The residue is then dewaxed in a second reactor with increasing feed circulation ("up-flow") into which 80 ml of catalyst containing 80 wt.% Of a ferrierite zeolite with Si / Al ratio = 10.2 and 20 wt. % alumina as well as 0.6 wt% Pt. The catalyst is then subjected to an atmosphere of pure hydrogen at a pressure of 10 MPa to ensure the reduction of platinum oxide to metallic platinum, after which the feed is finally injected. The total pressure is 10 MPa, the hydrogen flow rate is 1000 liters of gaseous hydrogen per liter of injected feed, the rate per volume part per hour is 2 hours and the reaction temperature is 350 ° C. After the reaction, the effluents are fractionated into light products (gasoline PI-150 ° C), average distillation products (150-380 ° C) and residue (380 + oC).

The properties of the obtained oil have been measured.

The table below shows the yields for the different fractions and the properties of the oils obtained directly with the feed and with the hydroisomerized effluents with catalyst A1 (according to the invention) which has subsequently been catalytically dewaxed.

35 1015036 ^ -28- Hydrotreated Hydroisomerized and Feed Catalytic Dewaxed Effluent

Catalyst / Al

Solvent dewaxing -20 ° C * catalytic dewaxed according to the example

Density of the effluents at 0.790 0.781

15 ° C

wt% 380 / effluents 58 67 wt% 380 + / effluents 42 33

Quality of the residue 380+

Yield of dewaxing 6 53 (wt%)

Yield oil / food 2.5 17.5

Oil quality VI (viscosity index) 143 137

Division into fractions _____ _ - _____ _ - W 42 32

Net conversion to 380 "(%) / 21.4 *. The solvent used is methyl isobutyl ketone. It is very clearly seen that the feed which is not hydroisomerized and dewaxed at -20 ° C has a particularly low yield of oil, while after the hydroisomerization and catalytic dewaxing operation the oil yield is much higher.

10

Example 3; production of high quality oil

The hydrocracking residue described in the table below is fed into a reactor containing a bed of a hydrotent 50 3R <-29 isomerization catalyst A2 and hydrogen under a total pressure of 7 MPa and in a volume ratio of H2 / HC = 600 Nl / NL. The spatial speed is then 1 hour on this catalyst. The reaction temperature is 326 ° C.

Catalyst A2 contains a support with 28 wt.% SiO2 and 72 wt.%

Al2 O3 on which 0.6 wt% Pt was deposited. The spread of Pt is 56%.

The effluent is collected, then it is distilled under vacuum to recover a fraction of 380 ° C *, the properties of which are listed in the following table.

The fraction 250-380 ° C corresponding to a gas oil fraction resulting from conversion hydroisomerization of the hydrocracking residue has a pour point of -20 ° C and a cetane index of 58, which is in fact an excellent gas oil.

The 380 ° C + fraction prepared above is then fed into a reactor containing a bed of a hydrogen dewaxing catalyst (0.5% Pt deposited on a support containing 75% ferrierite and 25% Al 2 O 3) and hydrogen under a pressure of 14 MPa and in an H2 / HC volume ratio = 1000 Nl / Nl. Spatial velocity is then 1 hour on this catalyst. The temperature of the reaction is 315 ° C.

A hydrofinishing catalyst containing 1 wt.% Pt, 1 wt.% F and 1 wt.% Is introduced into a second reactor placed after the first reactor. /% Cl on alumina. The product leaving the first reactor is fed into the second reactor, which is kept at a temperature of 220 ° C. The pressure is 14 MPa and the product circulates at a spatial speed of 0.5 hours.

The effluent is collected, then it is distilled under vacuum. The properties of the 380 ° C * residue are shown in the table.

This example demonstrates that the combination of a conversion hydroisomerization step (step a) and a catalytic dewaxing step results in higher quality products. In particular, it shows that step (a) allows to increase the viscosity of the oil fraction (380 ° C +) from 98 to 131 without lowering the pour point sufficiently (see table, columns 1 and 2). This reduction is achieved during step (b) with the catalytic dewaxing catalyst and yields a pour point of -18eC as well as a Saybolt color of +30 which gives the t 0 i üucl (λ j -30- product the quality of medicinal oil (see table, columns 2 and 3).

Table ΐ 2 3 feed = residue step (a) step (b) + hydrocracking hydro (hydroisomerization) finishing (catalytic dewaxing + hydro-finishing)

Temperature of the / 326 315 220 reaction ° C ____

Total (bar) 80 140 140

Conversion to 380 ° C- / 45 / (wt%) ____

Sulfur (wppm) 150 / /

Nitrogen (ppm by weight) 9 II

dl5 / 4 of the feed 0.8535 0.8360 / thing or the total effluent____

Content at 380 ° C + 81 / / in the diet____

Fraction 380 ° C +

Pour point (° C) +40 +26 ° 8

Color ASTM Dl 500 3 ^ 0 7

Fraction 380 ° C + after Fraction 380 ° C + of Fraction 380 ° C + of Fraction 380 ° C + treatment the residue of the hydro-isomerism of the hydro-hydrocracking and seren and de-isopheromization, ka-de-paraffinizing veneers with solution-analytical dewaxing -Veneers with solvent veneers and hydrofinishing VI 98 131 129

Pour point (° C) -15 -15 -18

Saybolt Color / / +30 UV Absorption / / (D2008) ____ 260-280 nm / / 0.0007 280-290 nm 7 7 0.0006 290-300 nm 7 7 0.0004 ______ _. 0.0002 _______. - <0.0001 101 503 6 ^ -31- - 2 3 300-330 nm 1 / 0.0002 _____ - _ <0.0001

This process also proves to be a very flexible process and makes it possible to obtain a wide range of yields and grades of oils and gas oils due to the ability to convert the viscosity index (or conversion) with the catalyst of step (a). adjust the hydroisomerization conversion and at the same time the presence or not of a distillation after step (a).

Thus, step (a) makes it possible to raise the VI to a higher level and thus partially compensate for the loss of VI formed during the catalytic dewaxing step.

1015036 ^

Claims (22)

A process for the production of oils from a hydrocarbon feed, the process comprising the following successive steps: 5 (a) conversion of the feed with simultaneous hydroisomerization of at least a portion of the n-alkanes of the feed, the feed having a sulfur content of less than 1000 wppm, a nitrogen content of less than 200 wppm, a metal content of less than 50 wppm, an oxygen content of at most 0.2%, this step being carried out at a temperature of 200-500 ° C, under a pressure of 2-25 MPa, at a spatial speed of 0.1-10 hr -1, in the presence of hydrogen and in the presence of a catalyst which deposited at least one precious metal on contains an amorphous acid carrier, the distribution of precious metal being between 20-100%. (b) catalytic dewaxing of at least a portion of the effluent from step <a), conducted at a temperature of 200-500 ° C, under a pressure of 1-25 20 MPa, at a volume parts per hour rate from 0.05-50 hours -1, in the presence of 50-2000 liters 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. The process according to claim 1, wherein for step (a) a catalyst is used which contains at least one precious metal deposited on an amorphous silica-alumina. 3. Process according to any one of the preceding claims, wherein for step (a) a catalyst is used which mainly consists of 0.05-10 wt.% Of at least one group VIII noble metal, deposited on an armorphous support of silica-alumina containing 5-90 wt% silicon oxide and having a specific surface BET of 100-500 m2 / g and the catalyst having an average pore diameter between 1-12 nm, 35. a porous volume of the pores whose diameter is between the mean diameter as previously determined less 3 nm 1 0 1 503 -33- and the mean diameter previously determined plus 3 nm greater than 40% of the total porous volume, a distribution of the precious metal between 20-100%, a distribution coefficient of the precious metal greater than 0.1. The process according to any of the preceding claims, wherein the noble metal of the catalyst of step (a) is platinum and / or palladium. The method of any preceding claim, wherein the entire effluent from step (a) is treated in step (b). The process according to any of claims 1 to 4, wherein the effluent from step (a) is distilled to separate the light gases and at least one residue containing the compounds having a boiling point higher than at least 340 ° C, the residue is subjected to step (b). The method of any preceding claim, wherein the effluent from step (b) is distilled to separate an oil containing the compounds having a boiling point greater than at least 340 ° C. 8. A method according to claim 7, comprising an atmospheric distillation followed by a distillation under vacuum of the atmospheric residue. 9. A method according to any one of the preceding claims, wherein the feed subjected to step (a) is previously subjected to a treatment with hydrogen, then optionally a separation of water, ammonia, and hydrogen sulfide. The process according to any of the preceding claims, wherein the catalyst of step (b) comprises at least one molecular sieve whose microporous system has at least one major type of channels with openings of pores having 9 or 10 atoms of T 30, wherein T is selected from the group consisting of Si, Al, P, B, Ti, Fe, Ga, interspersed with the same number of oxygen atoms, the distance between two accessible openings of pores with 9 or 10 T not exceeding 0.75 mm , and wherein said screen in the n-decane test has a 2-methylnonane / 5-methylnonane ratio greater than 5. The method of claim 10, wherein the screen is a zeolite selected from the group consisting of NU-10, EU-1, EU-13, 1015036¾ -34-ferrierite, ZSM-22, Theta-1, ZSM-50 , ZSM-23, NU-23, ZSM-35, ZSM-38, ZSM-48, ISI-1, KZ-2, ISI-4 and KZ-1. The method of claim 10 or 11, wherein the catalyst of step (b) further contains a noble metal selected from platinum 5 and / or palladium. The method of claim 12, wherein the precious metal is deposited on a support. The process according to any of claims 10 to 13, wherein the catalyst further contains a Group VI B metal. The method of any of claims 10 to 14, wherein the catalyst further contains phosphorus. A method according to any of the preceding claims, wherein the effluent from step (b) is subjected to a hydrofinishing step before being distilled. The method of claim 16, wherein the hydrofinishing catalyst contains platinum, chlorine and fluorine. A method according to claim 16 or 17, wherein the difference between THDPC (= temperature of the catalytic dewaxing stage) and Tjjcf (= temperature of the hydrofinishing stage) is between 20 ° and 200 ° C. The method of claim 18, wherein the difference is between 30 ° and 100 ° C. 20. A method according to any preceding claim, wherein the treated hydrocarbon feed contains at least 20% by volume of compounds boiling above 340 ° C. 21. A method according to any preceding claim, wherein the treated hydrocarbon feed is selected from the group consisting of the effluents from a Fischer-Tropsch unit, the vacuum distillation products from the direct distillation of the crude product, the vacuum distillation products from the of conversion units, the vacuum distillation products from units for the extraction of aromatics, the vacuum distillation products from the desulfurization or reaction with hydrogen of atmospheric residues and / or vacuum residues, disasphalted oils, hydrocracking residues or any mixture of the said feeds . 1015030¾ -35- Medicinal lubricating oil, obtained according to a method according to one or more of claims 16 to 21, which has a content of aromatic compounds of less than 0.1% by weight. ^ 0 1 50 3 6 ί