FR2805542A1 - Production of base oil from hydrocarbon material for lubricant, involves hydrogenating, isomerizing paraffin in charging material in presence of noble metal, and treating effluent formed by contact de-paraffin process - Google Patents

Abstract

The invention relates to an improved process for the production of very high quality base oils and for the simultaneous production of high quality middle distillates, comprising the successive steps of hydroisomerization and catalytic dewaxing. The hydroisomerization takes place in the presence of a catalyst containing at least one noble metal deposited on an amorphous acidic support, the metal dispersion being less than 20%. Preferably the support is an amorphous silica-alumina. The catalytic dewaxing takes place in the presence of a catalyst containing at least one hydro-dehydrogenating element (group VIII) and at least one molecular sieve (preferred zeolite). Preferably the sieve is chosen from zeolite NU-10, EU-1, EU-13 and ferrierite.

Description

The present invention relates to an improved process for producing very high quality base oils, ie having a high viscosity index (VI), a good UV stability and a low pour point, from hydrocarbon feedstocks (and preferably from hydrocarbon feedstocks from the Fischer-Tropsch process or from hydrocracking residues), possibly with simultaneous production of middle distillates (especially gas oils, kerosene) of very high quality, that is to say having a low pour point and a high cetane number. <U> previous </ U> High quality lubricants are of paramount importance for the proper functioning of modern machines, automobiles, and trucks. These lubricants are most often obtained by a series of refining steps to improve the properties of a petroleum cut. In particular a treatment of heavy petroleum fractions with high levels of linear paraffins or little branched is necessary in order to obtain base oils of good quality and with the best possible yields, by an operation which aims to eliminate linear paraffins or very poorly connected, loads that will then be used as base oils. Indeed, paraffins of high molecular weight which are linear or very weakly branched and which are present in the oils lead to high pour points and thus to freezing phenomena for low temperature applications. In order to decrease the pour point values, these linear paraffins which are not or very slightly connected must be completely or partially eliminated. Another means is catalytic treatment in the presence or absence of hydrogen and, given their shape selectivity, zeolites are among the most used catalysts. Zeolite catalysts such as ZSM-5, ZSM-11, ZSM-12, ZSM-22, ZSM-23, ZSM-35 and ZSM-38 have been described for use in these processes. All the catalysts currently used in hydroisomerization are of the bifunctional type associating an acid function with a hydrogenating function. The acid function is provided by supports with large surface areas (typically 150 to 800 m 2 / g) having a surface acidity, such as halogenated alumina (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 a plurality of metals of Group VIII of the Periodic Table of Elements, such as iron, cobalt, nickel, ruthenium, rhodium, palladium, osmium, iridium and platinum, or by a combination less a Group VI metal such as chromium, molybdenum and tungsten and less a Group VIII metal. The equilibrium between the two acid and hydrogenating functions is fundamental parameter which governs the activity and the selectivity of the catalyst. A weak acidic function and a strong hydrogenating function give catalysts which are not very active and selective towards isomerization whereas a strong acid function and a low hydrogenating function give very active and cracking-selective catalysts. 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 couple of the catalyst. The applicant therefore proposes, according to the method described in the invention, to jointly produce middle distillates of very good quality, VI oil bases and pour point at least equal to those obtained with a hydrorefining process and / or hydrocracking. <U> Object of the invention </ U> The applicant has focused his research efforts on the development of an improved process for manufacturing high quality middle quality distillate lubricating oils from fillers. hydrocarbons and preferably from hydrocarbon feeds from the Fischer-Tropsch process or from hydrocracking residues. The present invention therefore relates to a series of processes for the co-production of very high quality base oils and middle distillates (especially gasol) of very high quality from petroleum fractions. The oils obtained have a high viscosity index (VI), low volatility, good UV stabilization and a low pour point. More specifically, the invention relates to a process for the production of oils from a hydrocarbon feedstock (preferably at least 20 volume at a boiling point of at least 340 C), said process comprising the steps following successive steps (a) conversion of the feedstock with simultaneous hydroisomerization n-paraffins of the feed, said feedstock having a sulfur content of less than 1000 ppm wt, a nitrogen content of less than 200 ppm wt, a metal content of less than 50 ppm an oxygen content of at most 0.2 wt.%, said step taking place at a temperature of 200-500 C under a pressure of 5-25 Mpa with a space velocity of 0.1-5 h "", presence of hydrogen, and in the presence of a catalyst containing at least one noble metal deposited on an amorphous acid support, the noble metal dispersion being less than 20% (b) catalytic dewaxing of at least a 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 space velocity of 0.05-50 h -1, in the presence of 50-2000 liter of hydrogen / liter of effluent entering step (b) and in the presence 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 25 MPa, with a space velocity of 0.1 -6 h -1, in the presence of hydrogen in the volume ratio hydrogen / hydrocarbon of 100-2000 III, and in the presence of an amorphous catalyst comprising at least one metal of group VIII and less a metal of group VI B. The totality of the effluent from the step (a) can be sent in step (b). Step (a) is optionally 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 stage (preferably atmospheric) so as to separate the compounds having a boiling point below 340 C (gas, kerosene gasoline, diesel fuel) from the products having an initial boiling point of at least 340 ° C and which form the residue. Thus, at least one middle distillate fraction having a pour point of at most -20 ° C., and a cetane number of at least 50, are generally separated. The catalytic dewaxing step (b) then applies at least to the residue at the distillation end which contains compounds with a boiling point greater than at least 340 ° C. In another embodiment of the invention, the effluent resulting from step (a) has not distilled before to implement step (b). At most, undergoes a separation of at least a portion of the light gases (by flash ....) and then subjected to 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 pore-opening channel having 9 or 10 atoms T. T being selected from the group formed by Si, Al, P, B, Ti, Fe, Ga, alternating with an equal number of oxygen atoms, the distance between two accessible pore openings and comprising 9 or 10 atoms T being at most equal to 0.75 nm, and said sieve having a n-decane test has a ratio 2-methylnonane / 5-methylnonane greater than 5. Advantageously, the effluent from the dewaxing treatment is subjected to a distillation step advantageously comprising an atmospheric distillation and a distillation under vacuum so as to separate at least one oil fraction at a boiling point greater than at least 340 C. It most often has a pour point of less than -10 C and a VI greater than 95, a viscosity at 100 C at least 3cSt (or 3mm2 / s). This distillation step is essential when there is no distillation between steps (a) and (b). Advantageously, the effluent from the dewaxing treatment, optionally distilled, is subjected to a hydrofinishing treatment. <U> Detailed Description of the Invention </ U> The process according to the invention comprises the following steps <U> The feedstock </ U> The hydrocarbon feedstock from which the oils and possibly the middle distillates of high quality, at least 20 volumes of compounds boiling above 340 ° C., preferably at least 350 ° C. and advantageously at least 380 ° C., are preferably obtained. This does not mean that the boiling point is 380 ° C. and higher, but 380 C or more. The feed contains n-paraffins. Preferably the feed is an effluent from a Fischer-Tropsch unit. A wide variety of fillers can be processed by the process.

The feedstock may also be, for example, distillates from the direct distillation of the crude or from conversion units such as FCC, coker or visbreaking, or from aromatics extraction units, or from desulphurization or hydroconversion of RAT (atmospheric residues) and / or RSV (vacuum residues), or the charge may be a deasphalted oil, or a hydrocracking residue for example derived from or any mixture of the aforementioned fillers . The above list is not exhaustive. In general, the feedstocks suitable for the objective oils have an initial boiling point of at least 340 ° C. and more preferably greater than or equal to at least 370 ° C. The feedstock introduced into the conversion-hydroisomerization step (a) must be clean. . By "clean load" we mean the fillers 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 still, 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. The metal content of the filler such as nickel and vanadium is extremely low, ie less than 50 ppm by weight and more advantageously less than 10 ppm by weight, or better still less than 2 ppm by weight. In the case where the contents of unsaturated or oxygenated products are likely to cause excessive deactivation of the catalytic system, the feedstock (for example from the Fischer-Tropsch process) must, before entering the hydroisomerisation zone, undergo a hydrotreatment in a hydrotreating zone. Hydrogen is reacted with the feedstock in contact with a hydrotreatment catalyst whose role is to reduce the content of unsaturated and oxygenated hydrocarbon molecules (produced, for example, during Fischer-Tropsch synthesis). The oxygen content is thus reduced to at most 0.2% by weight. In the case where the charge to be treated is not specific to the meaning defined above, it is first subjected to a preliminary 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 group VIB element and at least one group VIII element, at a temperature of between 200 and 450 ° C., preferably 250-450 C advantageously 330-450 C or 360-420 C, at a pressure of 5 and 25 MPa or better less than 20 MPa, preferably between 5 and 20 MPa, the space velocity being between 0.1 and 6 h -1, preferably 0.3-3 h -1, and the amount of hydrogen introduced is such that the volume ratio of hydrogen to hydrocarbon is between 100 and 2000 liters / liter. The support is generally based (preferably essentially consisting of) of alumina or amorphous silica-alumina; it may also contain boron oxide, magnesia, zirconia, titanium oxide or a combination of these oxides. The hydro-dehydrogenating function is preferably filled with at least one metal or group VIII metal compound and VIB preferably selected from molybdenum, tungsten, nickel and cobalt. This catalyst may advantageously contain phosphorus; in fact, it is known in the prior art that the compound provides two advantages to hydrotreatment catalysts: an ease of preparation, especially when impregnating the nickel and molybdenum solutions, and a better hydrogenation activity.

The preferred catalysts are the NiMo and / or NiW catalysts on alumina, also the NiMo and / or NiW catalysts on alumina doped with at least one element included in the group of atoms formed by phosphorus, boron, silicon and fluorine, or still the NiMo and / or NiW catalysts on silica-alumina, on silica alumina-titanium oxide doped or not by at least one element included in the group of atoms formed by phosphorus, boron, fluorine and silicon. The total concentration of metal oxides of groups VIB and VIII is between 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) Group VIII is preferably between 20 and 1.25 and even more preferably between 10 and 2. The concentration of phosphorus oxide P205 will be less than 15% by weight and preferably 10% by weight. The product obtained at the end of the hydrotreatment undergoes, if necessary, an intermediate separation of water (H2O), H2S and NH3 so as to bring the contents of water, H2S and NH3 to values respectively lower than plus 100 ppm, 200 ppm in the feed introduced in step (a). It is possible at this level to possibly provide separations of the products having a boiling point of less than 340.degree. C. in order to treat in step (a) only one residue. Step (a): Hydroisomerization-Conversion <U> The catalyst </ U> The step takes place in the presence of hydrogen and in the presence of a bifunctional catalyst comprising at least one noble metal deposited on an amorphous acid support, dispersion in noble metal being less than 20%. During this step, the n-paraffins in the presence of a bifunctional catalyst are subjected to 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 of 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 more preferably at least 90%), noble metal particles have a size greater than 4 nm (% number). The support is amorphous, it does not contain molecular sieve; the catalyst does not contain molecular sieves either.

The amorphous acid support is generally chosen from the group formed by a silica-alumina, a halogenated alumina (preferably fluorinated), a silicon-doped alumina (deposited silicon), a titanium oxide alumina mixture, a tungsten-doped zirconia zirconia zirconia. and mixtures thereof with one another or with at least one amorphous matrix chosen from the group formed by alumina, titanium oxide, silica, boron oxide, magnesia, zirconia and clay, for example. A preferred catalyst according to the invention comprises (preferably consists essentially of) from 0.05 to 10% by weight of at least one Group VIII noble metal deposited on an amorphous silica-alumina support. The characteristics of the catalyst are more detailed <U> Silica content </ U>: the preferred support used for the production of the catalyst described in the context of this patent is composed of silica SiO 2 and alumina Al 2 O 3 synthesis. The silica content of the support, expressed as a weight percentage, 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 80%. 45%. This content is perfectly measured using X-ray fluorescence. <U> Nature noble metal </ U>: for this particular type of reaction, the metal function is provided by at least one noble metal of group VIII of the periodic table. elements and more particularly platinum and / or palladium. <U> noble metal content </ U>: the content of noble metal, expressed in% weight of metal relative to the catalyst, is between 0.05 to 10 and more preferably between 0.1 and 5. <U > Dispersion of the noble metal </ U>: the dispersion, representing the fraction of metal accessible to the reagent relative to the total amount of metal of the catalyst, can be measured, for example, by H2 / 02 titration. The metal is reduced beforehand, that is to say that it undergoes a high temperature underflow treatment of hydrogen under these conditions such that all the platinum atoms accessible to hydrogen are converted 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 PtO 2 form. By calculating the difference between the quantity of oxygen introduced and the quantity of oxygen leaving, the quantity of oxygen consumed is reached; ai *, we can then deduce from this last value the amount of platinum accessible to oxygen. The dispersion is then equal to the ratio of the quantity of platinum accessible to oxygen to the total amount of platinum of the catalyst. In our case, the dispersion is less than 20%, it is generally greater than 1% or more preferably 5%. <U> Size of </ U> particles <U> measured by Microscopy </ U> Electronics <U> to Transmission: </ U> in order to determine the size and distribution of the metal particles we used the Electron Microscopy to Transmission. After preparation, the catalyst sample is finely ground in an agate mortar and is then ethanol-dispersed. Samples at different locations to ensure good representativeness in size are made and deposited on a copper grid covered with a thin carbon film. Grids are then air dried under infrared lamp before being introduced into the microscope for observation. In order to estimate the average size of noble metal particles, several hundred measurements are made from dozens of shots. All of these measurements make it possible to produce a histogram of distribution of the particle size. Thus, we can accurately estimate the proportion of particles corresponding to each particle size domain. Distribution <U> of the noble metal </ U>: the distribution of the noble metal represents the distribution of the metal inside the catalyst grain, metal being able to be well or badly dispersed. Thus, it is possible to obtain the distributed plate I (for example detected in a ring whose thickness is much smaller 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 the reagents. In our case, the distribution of platinum is good, that is to say that the platinum profile, measured according to the method of the microprobe of Castaing, has a distribution coefficient greater than 0.1 advantageously greater than 0, 2 and preferably greater than 0.5. <U> Surface </ U> BET: BET surface area of the support is generally between 100 M2 / g and 500 M2 / g preferably between 250 m2 / g and 450M21g and for silica-based alumina supports, still more preferred between 310 M2 / g and 450 M2 / g. <U> Overall pore volume of the support </ U>: for supports based on silica-alumina, i is generally less than 1.2 ml / g and preferably of between 0.3 and 1.1 mmol, and even more advantageously less than 1.05 mllg. The preparation of the silica-alumina and any support in general is made by conventional methods well known to those skilled in the art. Advantageously, prior to the impregnation of the metal, the support may undergo calcination, 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 (about 7.5% preferred for an ice-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 of introducing the metal salt into a volume of solution which is equal to the pore volume of the catalyst mass to be impregnated. Prior to the reduction operation and to obtain the size distribution of the metal particles, the catalyst is calcined in humidified air at-750 ° C (550 ° C preferred) for 0.25-10 hours (preferred 2 hours). The partial pressure of H 2 O during the calcination is, for example, 0.05 bar to 0.50 bar (0.15 bar preferred). Other known methods of treatment making it possible to obtain the dispersion of less than 20% are suitable within the scope of the invention. In this step (a) the conversion is most often accompanied by a hydroisomerization of paraffins. The process has the advantage of flexibility: depending on the degree of conversion, production is more directed to oils or middle distillates. The conversion usually varies between 5-90%. Before use in the hydroisomerization-conversion reaction, the metal contained in the catalyst is reduced. One of the preferred methods for conducting the reduction of the metal is the treatment in 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 and then a rise in temperature up to 450 ° C. at a rate of 1 ° C./min and then a 2-hour plateau at 450 ° C. throughout this reduction step, the hydrogen flow rate of 1000 I hydrogen / 1 catalyst. Note 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 20 MPa and preferably 2 to 18 MPa, the space velocity will be between 0.1 h-1 and 10 h and preferably between 0.2 and 10h - 'is advantageously between 5 and 5.0h-1 and hydrogen content of between 100 and 2000 liters of hydrogen per liter of feedstock and preferably between 150 and 1500 liters of hydrogen per liter of feedstock. this step is between 200 and 450 ° C. and preferably from 250 ° C. to 450 ° C., advantageously from 300 ° to 450 ° C., and even more advantageously above 340 ° C., for example between 320 ° C. and 450 ° C., hydrotreating and hydroisomerization steps. The conversion can be carried out on both types of catalysts in (two or more) different reactors, and / or on at least two catalytic beds installed in one and the same reactor, as has been shown in US Patent No. 5,879,539. use of the catalyst The process described below in step (a) has the effect of increasing the viscosity index (VI) by + 10 points. More generally, it is found that the increase VI is at least 2 points, the VI being measured on a solvent-dewaxed charge (residue) and on the product resulting from the step (a) also dewaxed with solvent, aiming at a pour point temperature between -15 and -20 C.

An increase of VI of at least 5 points is usually obtained, and often more than 5 points or more than 10 points. It is possible to control the increase of VI, especially from the measurement of the conversion. It will thus be possible to optimize the production of high-VI oils or higher oil yields, but with lower VIs. <U> Treatment of the effluent from step (a) </ U> In a preferred embodiment, the effluent from step (a) of hydroisomerization-conversion can be completely treated in step (b) of dewaxing. In a variant, it may undergo a separation of at least a portion of at least a major part of light gases which comprise hydrogen and optionally also hydrocarbon compounds with at most carbon atoms. Hydrogen can be separated beforehand. The embodiment (except variant), with passage in step (b) of the entire effluent step (a), is economically interesting, since only one distillati unit used at the end of the process. In addition, at the final distillation (after catalytic dewaxing or subsequent treatments) a cold cold gas oil is obtained. Advantageously, in another embodiment, the effluent from step (a) is distilled so as to separate the light gases and also separate at least one residue containing the compounds with a boiling point greater than at least 340 ° C. It is preferably an atmospheric distillation. It can advantageously be distilled to obtain several fractions (gasoline, kerosene, diesel 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, that is to say without undergoing vacuum distillation. In another variant, vacuum distillation can be used.

In an embodiment more focused on a medium distill production objective, and still according to the invention, it is possible to recycle a portion of the residue from the separation step to the reactor containing the hydroisomerization conversion catalyst so as to convert it and increase the production of middle distillates. In general terms, the term "fraction (s)" in this text mean distillates having an initial boiling point of at least 150 ° C and a final value up to before the residue, that is to say generally up to 340 C, 350 C or preferably below 370 C or 380 C. The effluent from step (a) may undergo, before or after distillation, other treatments such as for example an extraction of at least a part of the aromatic compounds. Step (b): Catalytic Hydrodewaxing A part less of the effluent from step (a), effluent having optionally undergone the separations and / or treatments described above, is then subjected to a catalytic dewaxing step in the presence of hydrogen of a hydrodewaxing catalyst having an acid function, a hydro-dehydrogenating metal function and at least one matrix. It should be noted that compounds boiling above at least 340 ° C are still subjected to catalytic dewaxing. <U> The catalyst </ U> The acidic function is ensured by at least one molecular sieve and preferably a molecular sieve whose microporous system has at least one main type of channel whose openings are formed by rings containing 9 or 10 atoms T. atoms are the constituent tetrahedral atoms of the molecular sieve 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 constituting the channel openings, the atoms T, defined above, alternate with an equal number of oxygen atoms. It is therefore equivalent to say the openings are formed of rings which contain 9 or 10 oxygen atoms or rings which contain 9 or 10 atoms T. The molecular sieve used in the composition of the hydrodewaxing catalyst may also comprise other types of channels but whose openings are formed of rings which contain less than 10 atoms T or oxygen atoms. The molecular sieve used in 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 (1 nm = 10-9 m) of 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 performances in the hydrodewaxing stage. The bridge width measurement is carried out using a graphing and molecular modeling tool such as Hyperchem or Biosym, which allows to build the surface of the molecular sieves in question and, taking into account the ionic rays of the elements present in the framework of the sieve , to measure the bridge width. The preferred catalyst that is suitable for this process may also be characterized by a catalytic test called a standard test for converting pure n-decane which is carried out under a partial pressure of 450 kPa of hydrogen and a partial pressure of n = 1.2 kPa or a total pressure of 451.2 kPa in a fixed bed with a flow rate of n-constant of 9.5 ml / h, a total flow rate of 3.6 l / h and a catalyst mass of 0 g. The reaction is carried out in downflow. The conversion rate is set at the temperature at which the reaction takes place. The catalyst subjected to said test consisting of pure pelletized zeolite and 0.5% by weight of glati N-decane in the presence of the molecular sieve and a hydro-dehydrogenating function will undergo hydroisomerisation reactions which will produce isomerized products to 10 carbon atoms, and hydrocracking reactions leading to the formation of products containing less than 10 carbon atoms. Under conditions, a molecular sieve used in the hydrodewaxing step with the preferred catalyst according to the invention must have the physicochemical characteristics described above and, for a yield of isomerized products of nC, of the order of 5% by weight (the degree of conversion is regulated by the temperature), at a ratio of 2-methylnonane / 5-methylnonane greater than 5 and preferably greater than 7. The use of molecular sieves thus selected, under the conditions described hereinabove. above, among the many existing molecular sieves already, allows in particular the production of low pour point and high viscosity index products with good yields in the context of the process according to the invention. The molecular sieves which may be included in the composition of the preferred catalyst for catalytic hydrodewaxing are, by way of examples, the following zeolites Ferrierite, NU-10, EU-13, EU-1. Preferably the molecular sieves used in the composition of the hydrodewaxing catalyst are included in the group formed by ferrierite and zeolite EU-1. In general, the hydrodewaxing catalyst comprises a zeolite selected from the group consisting of NU-10, EU-1, -13, ferrierite, ZSM-22, Theta-1, ZSM-50, NU-23, ZSM. -35, ZSM-38, ZSM-23, ISI-1, -2, ISI-4, KZ-1. The weight content of molecular sieves in the hydrodewaxing catalyst is between 1 and 90%, preferably between 5 and 90% and even more preferably between 10 and 85%. The matrices used to carry out the shaping of the catalyst are, by way of examples and in a nonlimiting manner, luminescent gels, aluminas, magnesia, amorphous silica-aluminas, and mixtures thereof. Techniques such as extrusion, pelletizing or coating may be used to perform the shaping operation. The catalyst also comprises a hydro-dehydrogenating function ensured, for example, by at least one group VIII element and preferably at least one noble element comprised in the group consisting of platinum and palladium. The weight content of non-noble metal of group VIII, relative to the final catalyst, is between 1 and 40%, preferably between 1 and 30%. In this case, the non-noble metal is often associated with at least one Group VIB metal (Mo and W preferred).

If it is at least one noble metal of group VIII, the weight content, relative to the final catalyst, is less than 5%, preferably less than 3% and even more preferably less than 1.5. %. In the case of the use of Group VIII noble metals, platinum and / or palladium are preferably located on the matrix. The hydrodewaxing catalyst according to the invention may also contain from 0 to 20%, preferably from 0 to 10% by weight (expressed as oxides) of phosphorus. The combination of Group VIB metal (s) and / or Group VIII metal (s) with phosphorus is particularly advantageous. <U> The treatment </ U> A residue obtained at the end in step (a) and distillation and which is interesting to treat in this step (b) hydrodewaxing, has the following characteristics: it presents , 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 (before dewaxing), preferably at least 110 ° C. still more preferred less than 150, a higher viscosity at 100 C of 3 cSt (mm 2 / s), an aromatic content of less than 10 wt%, a nitrogen content of less than 10 ppm wt, a sulfur content of less than 50 ppm by weight or at 10 ppm by weight. The operating conditions in 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 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 velocity (vvh expressed as volume of feed injected per unit volume of catalyst per hour) is from about 0.05 to about 50 and preferably from about 0.1 to about 20 hours and more preferably more preferred between 0.2 and 10 hours. They are chosen to obtain the desired pour point. The contact between the feedstock and the catalyst is carried out in the presence of hydrogen. The level of hydrogen used and expressed in liters of hydrogen per liter of filler is between 50 and about 2000 liters of hydrogen per liter of filler and preferably between 100 and 1500 liters of hydrogen per liter of filler. <U> 'Effluent obtained </ U> The effluent leaving the hydrodewaxing step (b) is sent to the distillation train, which preferably incorporates atmospheric distillation and vacuum distillation, which has the following effect: the purpose of separating the conversion products of int boiling below 340 C and preferably below 370 C (and including in particular those formed during the catalytic hydrodewaxing stage), and to separate the fraction which constitutes the base oil and whose initial 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 various oil grades. Preferably, before being distilled, the effluent leaving the catalytic hydrodewaxing stage (b) is, at least in part and preferably, in its entirety, sent on a hydrofinishing catalyst (hydrofinition) in the presence of hydrogen so as to carry out advanced hydrogenation aromatic compounds which adversely affect the stability of oils and distillates. However, the acidity of the catalyst must be sufficiently low not to lead to the formation of cracking product boiling point below 340 C so as not to degrade the final yields including oils. The catalyst used in this step comprises at least one metal group VIII and / or at least one element of group VIB of the periodic table. The strong metal functions: platinum and / or palladium, or nickel-tungsten, nickel-molydbene combinations will advantageously be used to carry out a thorough hydrogenation of the aromatics. These metals are deposited and dispersed on an amorphous or crystalline oxide type support, such as, for example, aluminas, silicas, silica-aluminas. The hydrofinishing catalyst (HDF) may also contain at least one element of group VII A of the periodic table of elements. Preferably, these catalysts contain fluorine and / or chlorine. The weight contents of metals are between 10 and 30% in the case of non-noble metals and less than 2%, preferably between 0.1 and 1.5%, and even more preferably between 0.1 and 1.0 in the case of metals. The total amount of halogen is between 0.02 and 30%, preferably 0.01 to 15%, or even 0.01 to 10%, preferably 0.01 to 5%. Among the catalysts that can be used in this stage, hydrofinishing, and leading excellent performance, and in particular for obtaining medicinal oils, catalysts containing at least one noble metal group VIII (platinum example) and at least one halogen (chlorine and / or fluorine) the combination of chlorine fluorine being preferred. The operating conditions in which the hydrofinishing step of the process of the invention takes place are the following: the reaction temperature is between 180 and 400 ° C. and preferably between 210 and 350 ° C., advantageously between 230 ° C and 320 ° C .; the pressure is between 0.1 and 25 MPa (106 Pa) and preferably between 1.0 and 20; the hourly volume velocity (vvh expressed as the volume of feed injected per unit of lume of catalyst per hour) is between about 0.05 and about 100 and preferably between about 0.1 and about 30 h -1. The contact between the feedstock and the catalyst is carried out in the presence of hydrogen. The level of hydrogen used and expressed in liters of hydrogen per liter of filler is between 50 and about 2000 liters of hydrogen per liter of filler and preferably between 100 and 1500 liters of hydrogen per liter of filler. Advantageously, the temperature of the hydrofiniton step (HDF) is lower than the temperature of the catalytic chydrodéparaffinage (HDPC) step. The difference THDPc-THDF is generally between 20 and 200, and preferably between 30 and 100 C.

The effluent at the outlet of HDF is sent into the distillation train. <U> The products </ U> The base oils obtained according to this process have a pour point of less than 10 C, a VI greater than 95, preferably greater than 1 and even more preferably greater than 120, a viscosity of at least 3.0 to 100 C, an ASTM color of less than 1 and UV stability such that the ASTM color increase is 0 to 4 and preferably 0.5 to 2.5. The UV stability test, adapted from the ASTM D925- and D1148-55 methods, provides a quick method for comparing the stability of lubricating oils exposed to a source of ultraviolet light. The test chamber consists of a metal enclosure equipped with a turntable which receives the oil samples. A bulb producing the same ultraviolet rays as that of sunlight and placed at the top of the test chamber is directed downwards on the samples. Included in the samples is a standard oil with known U.V characteristics. The ASTM D1500 color of the samples is determined at t = 0 and after 45 hours of exposure at 55 C. The results are transcribed for the standard sample and the test samples as follows: a) initial color ASTM D1500, b) final color ASTM D1500, c) increased color, d) cloudiness, e) precipitate. Another advantage of the process according to the invention is that it is possible to achieve very low aromatic contents, less than 2% by weight, preferably 1% and better still less than 0.05% by weight. 'to the production of medicinal grade white oils with aromatic contents of less than 0.01 weight. These oils have UV absorbance values at 275, 295 and 300 nanometers respectively less than 0.8, 0.4 and 0.3 (ASTM D2008 method) and a Saybolt color between 0 and 30.

In a particularly interesting way, therefore, the process according to the invention also makes it possible to obtain medicinal white oils. Medical white oils are mineral oils obtained through advanced petroleum refining, their quality is subject to various regulations aimed at ensuring their safety for pharmaceutical applications, they are devoid of toxicity and characterized by their density and viscosity. White medicinal oils essentially comprise saturated hydrocarbons, they are chemically inert and their content of aromatic hydrocarbons is low. Particular attention is paid to aromatic compounds and in particular to 6 polycyclic aromatic hydrocarbons (PAHs for the abbreviation of polycyclic aromatic hydrocarbons) which are toxic and present at concentrations of one billion parts by weight of aromatic compounds in the oil. white. The control of the total aromatic content can be carried out by the ASTM D 2008 method, this UV adsorption test at 275, 292 and 300 nanometers makes it possible to control an absorbance less than 0.8, 0.4 and 0.3 respectively ( that is, the white oils have aromatic contents of less than 0.01% by weight). These measurements are carried out with concentrations of 1 g of oil per liter, in a 1 cm tank. The white oils marketed differ in their viscosity but also in their original crude which can be paraffinic or naphthenic, these two parameters will induce differences both in the physicochemical properties of the white oils considered but also in their chemical composition . At present, oil cuts, whether from direct distillation of a crude oil followed by extraction of the aromatic compounds by a solvent, or from catalytic hydrorefining or hydrocracking processes, still contain significant amounts of aromatic compounds. In the current legislative framework of the majority of the industrialized countries, the so-called medicinal white oils must have an aromatic content lower than a threshold imposed by the legislation of each country. The absence of these aromatic compounds in the oil cuts results in a Saybolt color specification which must be substantially at least 30 (+30), a maximum UV adsorption specification which must be less than 1.60-275. nm on a pure product in vat of centimeter and a maximum specification of absorption of the product of extraction by DMSO which must be lower than 0,1 for the American market (Food and Drug Administration, norm n 1211145). This last test consists of specifically extracting polycyclic aromatic hydrocarbons using a polar solvent, often DMSO, and controlling their content in the extract by UV absorption measurement in the range 260-350 nm. <U> Figures </ U> The invention will be illustrated with FIGS. 1 to 3, representing different embodiments for the treatment according to the invention of a load, for example, resulting from the Fischer-Tropsch process or from a hydrocracking residue. 1, the charge enters the line (1) in a hydrotreatment zone (which may be composed of one or more reactors, and comprise one or more catalytic beds of one or more catalysts) in which hydrogen enters (for example via line (3)) and where the hydrotreating step is carried out. The hydrotreated feedstock is transferred via the 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) where, in the presence of hydrogen, step (a) of hydroisomerization. the hydrogen can be brought via the pipe (8). In this figure, before being introduced into the zone (7), the charge to be hydroisomerized is freed of a large part of its water in the flask (5), the water leaving via the pipe (6) and optionally of the ammonia and hydrogen sulphide HZS, in the case where the charge entering through line 1 contains sulfur and nitrogen. The effluent from the zone (7) is sent via a pipe (9) into a flask (10) for separating the hydrogen which is extracted via a pipe (11), the effluent is then distilled at atmospheric pressure in the column (12) from which extracted through the pipe (13) a light fraction containing the compounds' at most 4 carbon atoms and those boiling below. It is also obtained at least one gasoline fraction (14) and at least one middle distillate fraction (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 to the catalytic dewaxing zone (18). catalytic dewaxing zone (18) (comprising one or more reactors, one or more catalytic beds of one or more catalysts) also receives hydrogen via a line (19) to carry out step (b) of the process. The effluent obtained leaving the line (20) is separated in a distillation train comprising, in addition to the balloon (21), a line (22) separating the hydrogen, an atmospheric distillation column (23) and a sub-column (24). which treats the residual atmospheric distillation transferred via line (25), which has an initial boiling point of greater than 340 ° C. It is obtained as products after distillations, an oil fraction (line 26) and boiling fractions more low, such as gas oil (line 27), kerosene (gas line (line 29), the light gases being eliminated through the line (30) of the atmospheric column and through the line (31) of the vacuum distillation column. The effluent leaving the pipe (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). can be added if needed in this area. The outgoing effluent is then transferred into the flask (21) and the described distillation train. To reduce the figure, hydrogen recycling has not been represented, whether it is the level of the flask (10) towards hydrotreatment and / or hydroisomerization, and / or at the level of the flask (21) towards the dewaxing and / or hydrofinishing. <U> Figure 2 </ U> We will recognize the references of Figure 1 here recovery. In an embodiment, all of the effluent from the conversion hydroisomerization zone (7) (step a) passes directly through line (9) into the catalytic dewaxing zone (18) (step b). <U> Figure 3 </ U> In the same way as above, the references of Figure 1 have been retained. In this embodiment, the effluent from the hydroisomerization-conversion zone (7) (step a) undergoes in the flask (32) a separation of at least a portion of the light gases (hydrogen and hydrocarbon compounds at plus 4 carbon atoms) for example by flash. The separated gases are removed via line (33) and the residual effluent is sent via line (34) to the catalytic dewaxing zone (18). It will be noted that in FIGS. 1, 2 and 3 a separation has been provided on the effluent from the catalytic dewaxing zone 1. This separation may not be implemented when said effluent is subsequently treated in a zone of hydrofinition, the separation having then well after said treatment.

Exemple 2 : Evaluation du catalyseur A1 en hydroisomérisation d'une charge Fischer-Tropsch suivi d'une séparation et d'un déparaffinage catalytique Le catalyseur dont la préparation est décrite dans l'exemple 1 est utilisé afin d'hydroisomériser une charge de paraffines issues de la synthèse Fischer-Tropsch dans le but d'obtenir des huiles. Afin de pouvoir directement utiliser les catalyseurs d'hydroisomérisation, la charge a été préalablement hydrotraitée et la teneur en oxygène amenée en dessous de 0,1 % poids. Les principales caractéristiques de la charge hydrotraitée sont les suivantes point initial 170 C point 10% 1970C point 50% 3500C point 90% 537 C point final 674 C fraction 380+ (% poids) 42 point d'écoulement + 73 C densité (<I>20I4)</I> 0,787 L'unité de test catalytique comprend un réacteur en lit fixe, à circulation ascendante de la charge ("up-flow"), dans lequel est introduit 80 ml de catalyseur. Le catalyseur est alors soumis à une atmosphère d'hydrogène pur à une pression de 10 MPa afin d'assurer la réduction de l'oxyde de platine en platine métallique puis la charge est enfin injectée. La pression totale est de 10 MPa, le débit d'hydrogène est de 1000 litres d'hydrogène gazeux par litre de charge injectée, la vitesse volumique horaire est de 2 h-' et la température de réaction de 350 C. Après réaction, les effluents sont fractionnés en produits légers (essence PI-150 C), distillats moyens (150- 380 C) et résidu (380+ C). Le résidu est alors déparaffiné dans un second réacteur à circulation ascendante de la charge ("up-flow"), dans lequel est introduit 80 ml de catalyseur contenant 80% poids d'une zéolithe Ferrierite de rapport Si/AI=10,2 et 20% poids d'alumine ainsi que 0,6% poids de Pt. Le catalyseur est alors soumi à une atmosphère d'hydrogène pur à une pression de 10 MPa afin d'assurer la réduction de l'oxyde de platine en platine métallique puis la charge est enfin injectée. La pression totale est de 10 MPa, le débit d'hydrogène est de 1000 litres d'hydrogène gazeux par litre de charge injectée, la vitesse volumique horaire est de 1 h-' et la température de réaction de 350 C. Après réaction, les effluents sont fractionnés en produits légers (essence PI-150 C), distillats moyens (150-380 C) et résidu (380+ C). This is the separation carried out in the flasks or columns 21, 24. EXAMPLE 1 Preparation of the Catalyst A1 According to the Invention The support is a silica-alumina used in the form of extrudates. It contains 29.3 weight SiO 2 silica and 70.7% Al 2 O 3 alumina. The silica-alumina, before addition of the noble metal has a surface of 330 M 21 g and its total pore volume is 0.87 cm 3 / g. The corresponding catalyst A is obtained after impregnation of the noble metal on the support. The platinum salt Pt (NH 3) 4 Cl 2 is dissolved in a solution flush corresponding to the total pore volume to be impregnated. The solid is then calcined for 2 hours in humidified air (H20 partial pressure = 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 cm 3 / g, the BET surface area, measured on the catalyst, equal to 287 m 2 / g and the mean diameter of the mesopores, measured on the catalyst, of 7 nm. The pore volume corresponding to the pores whose diameter is between 4 nm and 10 nm is 0.37 cm3 / g or 44% of the total pore volume. The platinum dispersion measured by H2 / 02 titration is 19%. The results obtained by local analyzes on Transmission Electron Microscopy snapshots indicate a distribution of noble metal particles whose fraction less than 2 nm represents traces of Pt, at most 2% weight of metal. The histogram of the fraction of particles larger than 2 nm is shown in the figure below. This histogram shows that particles having a size in the size range 13 6 nm represent at least 70% of the number of particles.

EXAMPLE 2 Evaluation of the Catalyst A1 in Hydroisomerization of a Fischer-Tropsch Filler followed by Catalytic Separation and Dewaxing The catalyst, the preparation of which is described in Example 1, is used to hydroisomerize a load of paraffins from of the Fischer-Tropsch synthesis in order to obtain oils. In order to be able to directly use the hydroisomerization catalysts, the feedstock was previously hydrotreated and the oxygen content brought below 0.1% by weight. The main characteristics of the hydrotreated feed are the following initial point 170 C point 10% 1970C point 50% 3500C point 90% 537 C end point 674 C fraction 380+ (% weight) 42 pour point + 73 C density (<I > 20I4) </ I> 0.787 The catalytic test unit comprises a fixed-bed reactor with up-flow of the charge ("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 platinum metal and the charge is finally injected. The total pressure is 10 MPa, the flow rate of hydrogen is 1000 liters of hydrogen gas per liter of feed injected, the hourly space velocity is 2 h -1 and the reaction temperature of 350 C. After reaction, the Effluents are fractionated into light products (PI-150 C gasoline), middle distillates (150- 380 C) and residue (380+ C). The residue is then dewaxed in a second upflow reactor, into which 80 ml of catalyst containing 80% by weight of a Ferrierite zeolite of Si / Al ratio = 10.2 and 20% by weight of alumina and 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 platinum oxide to platinum metal and then the load is finally injected. The total pressure is 10 MPa, the flow rate of hydrogen is 1000 liters of hydrogen gas per liter of feed injected, the hourly volume velocity is 1 hour and the reaction temperature of 350 C. After reaction, the Effluents are fractionated into light products (PI-150 C gasoline), middle distillates (150-380 C) and residue (380+ C).

The characteristics of the oil obtained are measured. The following table shows the yields for the different fractions and the characteristics of the oils obtained directly with the feedstock and with the effluents hydroisomerized on catalyst A1 (in accordance with the invention) and then catalytically dewaxed.

<SEP> Load <SEP> Effluent <SEP> and <SEP>
<tb> hydrotreated <SEP><U> w <SEP> paraffin </ U><SEP> catal <SEP> ti <SEP>
<tb> Catalyst <SEP> I <SEP> A1
<tb> Dewaxing <SEP> with <SEP> solvent <SEP> - <SEP> dewaxed <SEP> catalytically
<tb> 20 C * <SEP> according to <SEP><U> the example </ U>
<tb> Density <SEP> of <SEP> effluents <SEP> to <SEP> 15 C <SEP> 0.790 <SEP> 0,
<tb> weight <SEP> 380- / <SEP> effluents <SEP> 58
<tb> weight <SEP> 380 + / <SEP> effluents <SEP> 42
<tb> Quality <SEP> of <SEP> residue <SEP> 380+
<tb> Yield <SEP> of <SEP> 6
<tb> dewaxing <SEP>% <SEP><U> weight) </ U>
<tb> Yield <SEP> oil <SEP> / <SEP> load <SEP> 2.5 <SEP> 18,
<tb> Quality <SEP> of <SEP> oil
<tb> I <SEP>(<SEP>Index> of <SEP> Viscosity <SEP> 143 <SEP> 1
<tb> Breakdown <SEP> by <SEP> cuts
<tb> I-150 <SEP> 0
<tb> 1 <SEP> -380 <SEP> 58
<tb> 42
<tb> Convert <SEP> net <SEP> to <SEP> 380- <SEP> I <SEP> 2
<tb> * <SEP> solvent <SEP> used <SEP> is <SEP> the <SEP> methyl isobutyl ketone. It is very clearly noted that the non-hydroisomerized and dewaxed feedstock at -20 ° C exhibits an extremely low oil yield, whereas after the hydroisomerization and catalytic dewaxing operation, the oil yield is higher. Example 3 Evaluation of Catalyst A1 During a Test Performed to Produce Middle Distillates The procedure is the same as in Example 2, on the same charge, but the operating conditions on the first reactor containing the catalyst A1 are modified. The total pressure is 9 MPa, the flow rate of hydrogen is 1000 liters of hydrogen gas per liter of feed injected, the hourly space velocity is 9 h -1 and the reaction temperature of 355 C. After reaction, the effluents are fractionated light products (gasoline PI-150 C), kerosene (150-250 C), diesel (250-380 C) and residue (380+).

The following are the yields and the characteristics for the different fractions of the effluents hydroisomerized on catalyst A1.

Weight distribution) PI - 150 C: 18 150 - 250 C: 29 250 - 380 C: 43 380+: 10 Quality of the distillates: 150 - 250 C Smoke point: 48 mm Freezing point: - 31 C 250 - 380 C Cetane number: 62 Pour point: - 20 C The catalyst makes it possible to obtain good yields of middle distillates (weight fraction 150-250 C + weight fraction 250-380 C = 72% weight) starting from a load of paraffins from the Fischer-Tropsch synthesis and the middle distillates obtained are of very good quality. EXAMPLE 4 The hydrocracking residue whose characteristics are given in the table below is introduced into a reactor containing a fixed bed of catalyst, of hydroisomerisation-conversion as well as of hydrogen under a total pressure of 12 MPa and in a volume ratio H2 / HC = 1000 NI / NI. The space velocity is then 1 h -1 on this catalyst. The reaction temperature is 340 C.

Catalyst A2 contains a carrier having 28 wt% SiO 2 and 72 wt% Al 2 O 3 on which 0.5 wt% Pt has been deposited. The Pt dispersion is 15%.

The effluent is recovered and is then distilled under vacuum so as to recover a 380 C + fraction whose characteristics are reported in the table below.

The fraction 250-380 C which corresponds to a gas oil fraction and which results in the hydroisomerization converting hydrocracking residue has a pour point of -20 C and a cetane number of 57, which makes it an excellent gas oil. The 380 C + fraction prepared above is then introduced into a reactor containing a fixed bed of hydrodewaxing catalyst as well as hydrogen at a pressure of 14 MPa and in a volume ratio of H2IHC = 1000 NI / NI. The space velocity is then 1 h -1 on this catalyst. The reaction temperature is 315 C. The hydrodewaxing catalyst contains 0.5% Pt deposited on a support containing 75% ferrierite and% alumina. In a second reactor, a hydrofinishing catalyst containing 1% by weight of Pt, 1% by weight F and 1% by weight of CI on alumina is fed to a second reactor. The product from the hydrodewaxing reactor is introduced into this reactor which is maintained at a temperature of 220 ° C. The pressure is 14 MPa and the product circulates at a space velocity of 0.5 h -1.

The effluent is recovered and then distilled. The characteristics of the 380 C + residue are given in the table below. This example demonstrates the combination of a conversion-hydroisomerization step (step a) and a catalytic dewaxing step, resulting in products of high quality. In particular, it shows that step (a) makes it possible to increase the viscosity number of the oil fraction (380 C +) from 124 to 136 without sufficiently lowering the pour point (see table, columns 1 and 2). . This transformation carried out during step (b) makes it possible to reach a pour point of -20 ° C. on the catalytic dewaxing catalyst and a Saybolt color of +30 which gives the product the quality of medicinal oil ( see table, columns 2 and 3).

<U> Tab </ U>
<tb> 1 <SEP> 2
<tb> * Load <SEP> = <SEP> Residue <SEP> Step <SEP> (a) <SEP> Step <SEP> (b)
<tb> Hydrocracking <SEP> i. <SEP> e. <SEP> Hydrofinition
<tb> Hydroisomerization <SEP> i
<tb> conversion <SEP> Dewaxing
<tb> Catalytic <SEP> +
<tb> h <SEP> drofinition
<tb> Temperature <SEP> of <SEP> I <SEP> 340 <SEP> 315 <SEP> 220
<tb> reacti <SEP> C
<tb> P <SEP> total <SEP> bars <SEP> 120 <SE> 140 <SE> 140
<tb> Conversion <SEP> to <SEP> / <SEP> 45 <SEP> /
<tb> 380 C- <SEP> weight)
<tb> Sulfur <SEP> m <SEP><U> weight) </ U><SEP> 9 <SEP> /
<tb> Nitrogen <SEP> pm <SEP><U> weight) </ U><SEP> 1 <SEP> /
<tb> d1 <SEP> the <SEP> charge <SEP> 0.8421 <SEP> 0.8134 <SEP> 0 <SEP> 17
<tb> or <SEP><SEP> kill <SEP> total
<tb> Content <SEP> in <SEP> 380 C + <SEP> 88.5 <SEP><I> I <SEP> I </ I>
<tb> in <SEP> the <SEP><U> load </ U>
<tb> Fraction <SEP> 380 C +
<tb> Point <SEP>'flow<SEP> +42 <SEP> +38 <SEP> -20
<tb> (C
<tb> Coul <SEP> ASTM <SEP> 2.7 <SEP> / <SEP> /
<tb> D1500
<tb> Fraction <SEP> 380 C + '<SEP> Fraction <SEP> 380 C + <SEP> of <SEP> Fraction <SEP> 380 C + <SEP> of <SEP> Fraction <SEP> 380 C + <SEP> from
<tb> after <SEP> treatment <SEP> hydroisomerized <SEP> residue <SEP> and <SEP> hydroisomerized,
demineralized <SEP><SEP> hydrocracking <SEP> and <SEP> dewaxed <SEP> and
<tb> dewaxed <SEP> with <SEP> solvent <SEP> hydrofinish
<tb> solvent <SEP> catalytically
<tb> VI <SEP> 124 <SEP> 136 <SEP> 1
<tb> V1 <SEP> mm2 / s <SEP> 4.95 <SEP> 4.82 <SEP> 4,
<tb> Point <SEP>'flow<SEP> -18 <SEP> -18 <SEP> -20
<tb> C)
<tb> i
<tb> Coul <SEP> Saybolt <SEP> I <SEP> / <SEP> +30

i
<tb> Absorption <SEP> UV
<tb>; (D2008)
<tb> 260-280 <SEP> nm <SEP><I> I <SEP> I </ I><SEP> 0.0006
<tb> 280-290 <SEP> nm <SEP> / <SEP> I <SEP> 0.0005
<tb> 290-300 <SEP> nm <SEP> / <SEP> / <SEP> 0.0004
<tb> 300-360 <SEP> nm <SEP><I> I <SEP> I </ I><SEP> 0.0002
<tb> 360-400 <SEP> nm <SEP> / <SEP> I <SEP><0.0001
<tb><U> 300-330 <SEP> nm </ U><SEP> / <SEP> / <SEP> 0.0003
<tb> 330-350nm <SEP><I> I <SEP> I </ I><SEP><0.0001
<tb> Solvent <SEP> = <SEP> MIBK <SEP> (methyl isobutyl <SEP> ketone)
<tb> * Residue <SEP> from <SEP> of a <SEP><SEP> hydrocracking process <SEP> with <SEP> a <SEP> hydrotreatment <SEP> followed
<tb> of a <SEP> hydrocracking <SEP> zeolite.

Claims (18)

A process for producing medicinal oils having aromatic contents of less than 0.01 wt% from a hydrocarbon feedstock, said process comprising the following successive steps: (a) feed conversion with simultaneous hydroisomerization of n-paraffins of the feed, said feedstock having a sulfur content of less than 1000 ppm wt, a nitrogen content of less than 200 ppm wt, a metal content of less than 50 ppm wt, an oxygen content of not more than 0.2 wt% said step being carried out at a temperature of 200-500 C under a pressure of -25 MPa, with a space velocity of 0.1 - 5h- ', in the presence of hydrogen, presence of a catalyst containing at least one noble metal deposited amorphous acid support, the noble metal dispersion is less than 20%, (b) catalytic dewaxing of at least a portion of the effluent from step (a), "at a temperature of 200 - 500 C under a pressure of 1- 25, with an hourly space velocity of 0.05-50h-1, in the presence of 50-2000 liter of hydrogen / liter of effluent entering step b and in the presence of catalyst comprising at least one hydro-dehydrogenating element less a molecular sieve. 2. The method of claim 1 wherein the entire effluent of the step is ité in step (b). 3. Method according to 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 subjected to step (b). 4. Method according to one of the preceding claims wherein the effluent from step (b) is distilled to separate an oil containing compounds boiling point greater than at least 340 C. 5. Process according to claim 4 comprising atmospheric distillation followed by vacuum distillation of the atmospheric residue. 6. Method according to one of the preceding claims wherein the feedstock subjected to step (a) has previously undergone hydrotreatment and 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 the noble metal particles having a size less than 2 nm represents at most 2% by weight of the noble metal deposited on I 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 selected from the group consisting of a silica-alumina, a logenated alumina, a silicon-doped alumina, a mixture alumina-titanium oxide zirconia sulfated, a zirconia tungsten-doped, alone or in a mixture. 10. The method of claim 9 characterized in that the support further comprises at least one amorphous matrix selected from the group consisting of 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. Process according to one of the preceding claims, characterized in that the noble metal of the catalyst of step (a) and the hydro-dehydrogenating metal catalyst of step (b) are chosen from the group formed by platinum and palladium. 14. The method as claimed in one of the preceding claims, in which the catalyst in step (b) comprises at least one molecular sieve whose microporous system has at least one main type of pore-opening channel having 9 1 T. being selected from the group consisting of Si, Al, P, B, Ti, Fe, alternating with an equal number of oxygen atoms, the distance between two accessible pore openings at 9 or 10 T atoms is at most 0.75 nm, said sieve having in the n-decane test a 2-methylnonane / 5-methylnonane ratio greater than 5. The process according to claim 14 wherein the sieve is a zeolite selected from the group consisting of Nu-10, EU-1, EU-13, ferrierite, ZSM-22, theta-1, ZSM-ZSM-23, Nu- 23, ZSM-35, ZSM-38, ISI-1, KZ-2, ISI-4, KZ-1. 16. Method according to one of the preceding claims wherein the effluent from step <B> (</ B> b) is subjected to a hydrofinition step before being distilled. 17. Method according to one of the preceding claims wherein the treated hydrocarbon feedstock contains at least 20% volume of compounds boiling above 340 C. 18. Method according to one of the preceding claims wherein the treated hydrocarbon feedstock is selected from the group consisting of effluents from Fischer-Tropsch unit, vacuum distillates from the direct distillation of the crude, vacuum distillates from conversion units, vacuum distillates from aromatics extraction units, vacuum distillates from desulphurisation or hydroconversion of atmospheric residues and / or vacuum residues, desulfurized oils, hydrocracking or any mixture said charges.