MXPA99004794A - Method for improving the pour-point of paraffin feedstock with a nu-86 zeolite based catalyst - Google Patents

Abstract

The invention concerns a method for improving the pour-point of a feedstock containing paraffin of more than 10 carbon atoms, whereby the feedstock to be treated is contacted with a catalyst containing NU-86 zeolite and at least a hydro-dehydrogenizing element, at a temperature between 170 and 500°C, pressure between 1 and 250 bars and a horary volume velocity between 0.05 and 100 h -1, in the presence of hydrogen at the rate of 50 to 2000 l/l of feedstock. For heavy feedstock, the resulting product is fractionated for producing at least a fraction containing at least a middle distillate with reduced pour-point, and a residue containing the oil bases with reduced pour-point and high viscosity index. Preferably the NU-86 zeolite is dealuminized.

Description

PROCESS FOR IMPROVING THE FLUIDITY POINT OF PARAFFINIC LOADS WITH A CATALYST BASED ON ZEOLITA NU-86 The present invention relates to a process for improving the displacement point of paraffin-containing charges, linear and / or slightly branched, long (more than 10 carbon atoms), in particular to convert, with a good yield, the charges that they have high pour points in at least one cut that has a low pour point. This cut can be a middle distillate and / or an oil base, which then has a high viscosity index.

Previous art High quality lubricants are of paramount importance for the proper functioning of modern machines, cars, and trucks. Meanwhile, the quality of paraffins exiting directly from oil, untreated, and possessing the proper properties to constitute good lubricants is very low with respect to the growing demand in this sector. REF .: 30229 The treatment of heavy oil fractions of large contents of linear or little branched paraffins is necessary in order to obtain base oils of good quality and this with the best possible yields, by an operation that focuses on eliminating linear paraffins or very little ramified, the charges that will be used immediately as base oils or as kerosene or as a carborreactor (jet fuel).

In fact, paraffins with high molecular weights that are linear or very little branched and that occur in oils or in kerosene or carborreactor lead to high pour points and consequently to freezing phenomena for uses based on temperature . In order to decrease the values of the pour points, these linear or little branched paraffins must be completely or partially removed.

This operation can be carried out by solvent extraction such as propane or methyl ethyl ketone, then deparaffinization is discussed with propane or methyl ethyl ketone (MEK). Meanwhile, these techniques are expensive, long and never easy to use.

Another means is a selective thermal decomposition of the longer linear paraffin chains that lead to the formation of lower molecular weight compounds in which a part can be removed by distillation.

Taking into account their selectivity in form, zeolites are among the most used catalysts. The idea that foresees its use is that there are zeolitic structures in which the openings of the pores are such that they allow the entry into their microporosity of long linear paraffins or very little branched but that exclude the branched paraffins, nafteños and aromatics. This phenomenon thus leads to a selective thermal decomposition of linear or very slightly branched paraffins.

Catalysts based on zeolites having intermediate pore sizes such as ZSM-5, ZSM-11, ZSM-12, ZSM22, ZSM-23, ZSM-35 and ZSM-38 have been described for use in these processes.

The processes using certain of these zeolites allow oils to be obtained by thermal decomposition of fillers containing amounts of linear or very little branched paraffins of less than 50% by weight. Meanwhile, for the loads containing higher amounts of these compounds it seems that their thermal decomposition by said zeolites leads to the formation of important quantities of light products of low molecular weights, such as butane, propane, ethane and methane, which considerably reduces the performance on investigated products. Other zeolites (SZM-22 for example) favor an isomerization of these compounds and are more dedicated to the production of oils with high yields.

The applicant has put his research efforts into the preparation of an improved point of flow reduction process thanks to the use of NU-86 zeolite-based catalyst. This process, applied to heavy cuts, allows to produce at the same time distillates means of low pour point and a residue that includes the bases of oils with low pour point and high viscosity index.

Objective of the invention The object of the invention is a process for improving the pour point of a paraffinic charge containing paraffins of more than 10 carbon atoms, in which the charge to be treated is contacted with a catalyst based on zeolite Nü-86 and containing at least one hydrodehydrogenating element, at a temperature comprised between 170 and 500 ° C, a pressure between 1 and 250 bar and an hourly volumetric velocity between 0.05 and 100 h_1, in the presence of hydrogen at a ratio of 50 to 2000 1/1 load. In the case of heavy load treatment, the product obtained is fractionated in such a way as to obtain at least one cut that includes at least a medium pour point distillate and a residue that includes the low pour point oil bases. high viscosity index.

The zeolite NU-86, in hydrogenated form, designated by H-NU-86 and obtained by calcination and / or ionic changes of the crude synthesis NU-86 zeolite, used in the process according to the invention as well as its mode of synthesis is described in patent EP-0463768 A2. This zeolite NU-86 is characterized by an X-ray diffraction table that is as follows: X-ray diffraction table of zeolite H-NU-86 I / lo represents the relative intensities of graduated peaks according to the following scale: f = low (I / it comprises between 0 and 20), = medium (I / Io comprises between 20 and 40), F = Large (I / Io comprises between 40 and 60), TF = Very Large (I / it comprises between 60 and 100), (1) indicates that it is a long and asymmetric line that contains a certain number of peaks, among which the largest are those that lie in the reticular equidistance dhkl of 11.80, 11.10 and 10.60. (2) indicates that the line is made up of a doublet. However, in certain cases it can be proved that in the diffractogram the doublet is not solved and that consequently it appears in the form of a single unresolved peak.

The type of this zeolite is not yet officially attributed by the synthesis committee of the IZA (International Zeolite Association). Meanwhile, following the works published in the 9th. International Congress on Zeolites by J.L. Casci, P.A. Box and M.D. Shannon (, Proceedings of the 9th International Zeolite Conference, Montreal 1992, Eds R. Von Ballmoos et al., 1993 by Butterworth) seems that: zeolite NU-86 has a three-dimensional microporous system; This three-dimensional microporous system consists of straight channels in which the pore opening is delimited by 11 T atoms (tetrahedral atoms: Si, Al, Ga, Fe ..), of straight channels delimited alternately by openings of 10 to 12 T atoms and sinusoidal channels delimited alternately by openings of 10 to 12 T atoms.

The term "pore opening" means 10, 11 or 12 tetrahedral atoms (T) of pores consisting of 10, 11 or 12 sides.

It will also be understood in this text by "zeolite NU-86" zeolite NU-86 containing silicon and at least one element T chosen from the group consisting of Al, Fe, Ga, B, and preferably aluminum.

Preferably, the NU-86 zeolite used has been dealuminated or more generally, at least part of the T element has been removed, and then possesses a Global atomic T / N advantageously greater than about 20. Extraction of element T from the zeolitic structure (or network) is preferably carried out by at least one heat treatment, optionally carried out in the presence of steam, followed by at least one acid attack or by a direct acid attack, by at least one solution of a mineral or organic acid.

Preferably, the global atomic Ti / T ratio of said zeolite is greater than about 16 and advantageously greater than about 20, preferably greater than about 22, and even more preferred is from about 22 to about 300, or about 250.

The "dealuminated" zeolite NU-86 is at least partly, preferably almost completely, in acid form, ie in the form of hydrogen (H +). The atomic ratio Na / T is generally lower than 0.7% and preferably lower than 0.6% and even more preferred lower than 0.4%.

Selling this process allows converting a load that has a high pour point into a product that has a lower pour point. This can be a medium distillate cut with reduced pour point (gas oils for example) and / or an oil base with low pour point and high viscosity index.

The charge is composed, among others, of linear and / or slightly branched paraffins having at least 10 carbon atoms, preferably 15 to 50 carbon atoms and advantageously 15 to 40 carbon atoms.

An advantage of the catalyst containing the molecular sieve of NU-86 is that it does not lead to the very important formation of light products.

On the other hand the catalyst has at least one hydro-dehydrogenating function, for example a metal of group VIII or a combination of at least one metal or compound of group VIII and at least one metal or compound of group VI, and the reaction is carried out in the conditions described above.

The use of zeolite NU-86 according to the invention under the conditions described above allow, in particular, the production of products with low pour point and also products with a high viscosity index, with good yields.

Detailed description of the invention Zeolite NU-86 has an atomic Si / T ratio (Preferred) comprised between 8 and 1000 and in particular between 8.5 and 16 by the zeolites obtained for synthesis, and an atomic ratio Si / T of more than 16 and advantageously of more than 20 for the zeolites in which at least one part of the element T has been removed.

To prepare the dealuminated NU-86 zeolite according to the invention, in the preferred case where T is Al, two dealumination methods can be employed, starting from the crude synthesis NU-86 zeolite containing organic structure. They described below. But any other method known to the person skilled in the art also falls within the scope of the invention, as well as any method applicable when T is different from Al.

The first method that speaks of direct acid attack comprises a first stage of calcination under dry air flow, at a temperature generally comprised between approximately 450 and 550 ° C, which has the purpose of eliminating the organic structure present in the microporosity of the zeolite , followed by a treatment step by an aqueous solution of a mineral acid such as HN03 or HCl or organic such as CH3C02H. This last stage can be repeated as many times as necessary in order to obtain the desired level of dealumination. Between these two steps it is possible to make one or more ionic changes by at least one solution of NH4N03, so as to eliminate at least partially, preferably practically completely, the alkali cation, in particular sodium. Also, for the purpose of dealumination treatment by direct acid attack, it is possible to make one or more ionic changes by at least one solution of NH4N03, so as to eliminate residual alkali cations and in particular sodium.

To reach the desired Si / Al ratio, it is necessary to choose the operating conditions well; from this point of view the most critical parameters are the treatment temperature for the aqueous acid solution, the concentration of the latter, its nature, the ratio between the amount of acid solution and the mass of zeolite treated, the duration of the treatment and the number of treatments performed.

The second method that talks about heat treatment (in particular with water vapor or "vaporization") + acid attack, comprises, at first, the calcination under dry air flow, at a temperature generally comprised between approximately 450 and 550 ° C, which aims to eliminate the organic structure occluded in the microporosity of the zeolite.

Then the solid thus obtained is subjected to one or more ionic changes with at least one solution of NH4N03, so as to eliminate at least partially, preferably practically completely, the alkaline cation, in particular sodium, present in the cationic position in the zeolite. The zeolite thus obtained is subjected to at least one cycle of dealumination of the structure, comprising at least one thermal treatment carried out, optionally and preferably in the presence of steam, at a temperature generally comprised between 550 and 900 ° C, and optionally followed by at least one acid attack by an aqueous solution of a mineral or organic acid. The calcination conditions in the presence of water vapor (temperature, water vapor pressure and duration of treatment) as well as post-calcination acid attack conditions (duration of attack, acid concentration, nature of the acid used and the relationship between the volume of acid and the mass of zeolite), are adapted in order to obtain the desired level of dealumination. With the same purpose you can also play with the number of thermal treatment-acid attack cycles that are carried out.

In the preferred case where T is Al, the dealumination cycle of the structure, which contains at least one thermal treatment step, optionally carried out and preferably in the presence of water vapor, and at least one etching step in an acid medium of the NU-86 zeolite can be repeated as many times as necessary to obtain the dealuminated NU-86 zeolite having the desired characteristics. Also, after the thermal treatment, optionally carried out and preferably in the presence of water vapor, several successive acid attacks can be operated with the acid solutions in different concentrations.

A variant of this second calcination method may consist in carrying out the heat treatment of the zeolite NU-86 containing the organic structure, at a temperature generally comprised between 550 and 850 ° C, optionally and preferably in the presence of water vapor. In this case, the calcination stages of the organic structure and the dealumination of the structure are carried out simultaneously. Then, the zeolite is optionally treated with at least one aqueous solution of a mineral acid (for example HN03 or HCl) or organic acid (CH3C02H for example). Finally, the solid thus obtained can optionally be subjected to at least one ion exchange with at least one NH4N03 solution, so as to eliminate practically any alkali cation, in particular sodium, present in the cationic position in the zeolite.

The sieve (zeolite NU-86) generally contains at least one hydrodehydrogenating element, for example at least one metal of group VIII, preferably a noble metal and advantageously chosen from the group consisting of Pt or Pd, which is It is introduced into the molecular sieve for example by dry impregnation, for ion exchange or any other method known to the person skilled in the art.

The metal content thus introduced, expressed in % by weight with respect to the mass of the molecular sieve, is generally less than 5%, preferably less than 3% and in general from 0.5% to 1% by weight.

In the case of treatment of a real load the molecular sieve according to the invention is previously formed, according to a first variant, the molecular sieve can be subjected to the deposit of at least one metal of group VIII preferably chosen from the group formed by platinum and palladium, and is formed by any technique known to the person skilled in the art. It is possible in particular to mix in a matrix, generally amorphous, for example in a moist powder of alumina gel. The mixture is then shaped, for example by extrusion through a row. The content in the molecular sieve of the mixture thus obtained is generally between 0.5 and 99.9% and advantageously between 5 and 90% powder with respect to the mixture (molecular sieve + matrix).

From now on the text will be designated by the term support the mixture molecular sieve + matrix.

The formation can be carried out with other matrices such as alumina, such as for example magnesia, amorphous silica-aluminas, natural clays (kaolin, bentonite, sepiolite, attapulgite), silica, titanium oxide, boron oxide, zirconia, aluminum phosphates, titanium phosphates, zirconium phosphates, carbon and their mixtures. Other techniques such as extrusion, such as pelletizing or peeling, can be useful.

The hydrogenating metal of group VIII, preferably Pt and / or Pd, can also be deposited on the support for any process known to the person skilled in the art and allowing the deposition of the metal in the molecular sieve. The cation exchange technique can be used with competition where the competitor is preferably ammonium nitrate, the competition ratio which is equal to at least about 20 and advantageously about 30 to 200. In the case of platinum or palladium, it is used usually a platinum tetramine complex or a palladium tetramine complex: the latter will then be deposited almost entirely on the molecular sieve. This cation exchange technique can also be used to directly deposit the metal on the molecular sieve powder, which has its optional mixture with a matrix.

The deposit of the metal (or metals) of group VIII is generally followed by a calcination with air or oxygen, usually between 300 and 600 ° C for 0.5 to 10 hours, preferably between 350 ° C and 550 ° C for 1 to 4 hours. It is possible to proceed immediately with a reduction under hydrogen, generally at a temperature between 300 and 600 ° C for 1 to 10 hours, preferably between 350 ° C and 550 ° C for 2 to 5 hours.

Platinum and / or palladium can also be deposited not directly on the molecular sieve, but on the matrix (the aluminum bond), before or after the forming step, which uses an anion exchange with hexachloroplatinic acid, the acid hexachloropaládico and / or the palladium chloride in the presence of a competitor agent, for example hydrochloric acid. In general after deposition of platinum and / or palladium, the catalyst as before is subjected to a calcination and then reduced in hydrogen as indicated above.

The hydrodehydrogenating element can also be a combination of at least one metal or compound of group VI (for example molybdenum or tungsten) and at least one metal or compound of group VIII (for example nickel or cobalt). The total metal concentration of groups VI and VIII, expressed in metal oxides with respect to the support, is generally between 5 and 40% by weight, preferably between 7 and 30% by weight. The weight ratio (expressed in metal oxides) metals of group VIII on metals of group VI is preferably between 0.05 and 0.8; preferably between 0.13 and 0.5.

The above preparation methods are useful for depositing these metals.

This type of catalyst can advantageously contain phosphorus, wherein the content, expressed as phosphorus oxide P205 with respect to the support, will generally be less than 15% by weight, preferably less than 10% by weight.

The fillers that can be treated according to the process of the invention are advantageously the fractions that possess the relatively high pour points in which it is desired to decrease the value.

The process according to the invention can be used to treat the varied fillers having relatively light fractions such as kerosenes and carborreactors up to the charges having higher boiling points such as middle distillates, vacuum residues, gas oils.

The load to be treated is in most cases a C10 + cut of initial boiling point greater than about 175 ° C, preferably a cut of the initial boiling point above at least 280 ° C. For the production of oils, heavy loads are used, ie constituted by at least 80% by volume of compounds with boiling points of at least 350 ° C, preferably between 350-580 ° C, and advantageously at least 380 ° C . The process according to the invention is particularly adapted to treat paraffinic distillates such as middle distillates that include gas oils, kerosenes, carborreactors, to treat vacuum residues and other fractions in which the pour point and the viscosity must be adapted to enter the framework of the specifications, and for example the middle distillates from FCC (LCO and HCO) and the hydrodecomposition waste.

The fillers that can be treated according to the process of the invention can contain paraffins, olefins, naphthenes, aromatics and also heterocycles and with an important proportion of high molecular weight n-paraffins and very little branched paraffins also of high molecular weight.

Typical fillers that can be advantageously treated according to the invention generally have a pour point above 0 ° C. The products resulting from the treatment according to the process have pour points lower than 0 ° C and preferably lower than approximately -10 ° C.

These charges have contents of n-paraffins, of more than 10 carbon atoms, of high molecular weights and of paraffins, of more than 10 carbon atoms, very little branched also of high molecular weights, greater than 30% and up to approximately 90 %, even in certain cases greater than 90% by weight. The process is particularly interesting when this ratio is at least 60% by weight.

Examples which may be mentioned are other fillers which are treatable according to the invention and are not limiting, the bases for lubricating oils, the synthesis paraffins from the Fischer-Tropsch process, the high-melting polyalphaolefins, the synthesis oils, etc. The process can also be applied to other compounds containing an n-alkane chain as defined above, for example the n-alkylcycloalkane compounds, which contain at least one aromatic group.

The operating conditions in which the process of the invention is operated are the following: the reaction temperature is between 170 and 500 ° C and preferably between 180 and 470 ° C, advantageously 190-450 ° C; the pressure is between 1 to 250 bar and preferably between 10 and 200 bar; the hourly volumetric velocity (vvh expressed in injected load volume per unit volume of catalyst per hour) is between about 0.05 and about 100 and preferably between 0.1 and about 30 h -1.

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

The charge to be treated preferably has a nitrogen compound content of less than about 200 ppm and preferably less than 100 ppm by weight. The sulfur content is less than 1000 ppm by weight, preferably less than 500 ppm and even more preferably less than 200 ppm by weight. The metal content of the filler, such as Ni or V, is extremely low, ie less than 50 ppm by weight, preferably less than 10 ppm by weight and even more preferably less than 2 ppm by weight.

In the case where a heavy load is treated to supply an oil base, the product obtained, after treatment of the heavy load with the zeolite-based catalyst NU-86, is fractionated into at least one cut including at least one low pour point distillate, and in a residue that includes the base oils of low pour point and high viscosity index.

The middle distillate can be a kerosene (a cut generally considered to be boiling points 150 - less than 250 ° C), a diesel (heavier cut than kerosene, generally considered to be at least 250 ° C and less than 400 ° C , or less than 380 ° C). The oil is then between the 380+ or 400+ residue. The cut-off points can be more or less variable according to the operator's constraints.

The following examples illustrate the invention without limiting the scope in any way.

Example 1 The material used first is a zeolite NU-86, which is prepared according to example 2 of the EP patent 0 463768 A2 and has a global atomic Si / Al ratio equal to 10.2 and an atomic ratio Na / Al equal to 0.25.

This Nu-86 zeolite first undergoes a calcination called dry at 550 ° C under dry air flow for 9 hours. Then the solid obtained is subjected to four ion exchanges in a solution of NH4N03 ION, at approximately 100 ° C for 4 hours for each exchange. The solid thus obtained is referenced NH4-NU-86/1 and has a Si / Al ratio = 10.4 and a Na / Al ratio = 0.013. Its other physicochemical characteristics are grouped in Table 1.

The values were determined as follows: From X-ray diffraction diagrams, for each sample, the total surface of the signal is measured on an angular surface (2) from 6 to 40 °, then, in the same area, the striped surface in number of pulses for a step-by-step recording of 3 seconds with steps of 0.02 ° (2). The ratio of these two values, Stripe surface / Total surface, is characteristic of the amount of crystallized matter in the sample. This relationship or "peak rate" is immediately compared, for each treated sample, with the peak rate of a reference standard arbitrarily considered as totally (100%) crystallized. The crystallinity rate is therefore expressed as a percentage with respect to a reference, which is important to choose, because the relative intensity of the rays varies according to the nature, proportion and position of the different atoms in the unit. the structure, and in particular the cations and the structure. In the case of the measurements made in the examples of the present description, the chosen reference is the form calcined under dry air and changed 3 times, successively, by a solution of ammonium nitrate of the zeolite NU-86.

It is also possible to estimate the microporous volume from the amount of nitrogen adsorbed at 77 K for a partial pressure P / Po equal to 0.19, by way of indication.

Table 1 The crystallites of zeolite NU-86 are in the form of crystals in which the size varies from 0.4 μm to 2 μm.

The zeolite NH4-NU-86/1 is kneaded with the alumina of type SB3 provided by the company Condéa. The kneaded dough is then extruded through a row with a diameter of 1.2 mm. The extrudates are then calcined at 500 ° C for 2 hours with air and then dry impregnated with a solution of platinum chloride tetramine [Pt (NH3) 4] Cl2, and finally calcined with air at 550 ° C. The content of platinum in the final catalyst Cl thus obtained is 0.7% by weight and the content of zeolite expressed with respect to the mass group of the catalyst is 20% by weight.

Example 2: Evaluation of the catalyst Cl The Cl catalyst was evaluated to treat a hydrodecomposition residue left from a vacuum distillate.

The characteristics of this load are the following: The catalyst Cl in which the preparation described in Example 1 is used to prepare a base oil from the filler described above.

The catalyst is pre-reduced in hydrogen at 450 ° C before catalytic testing in situ in the reactor. This reduction is effected by stopping from time to time. It consists of a stage at 150 ° C for 2 hours, then an increase in temperature up to 450 ° C at the speed of 1 ° C / min, then a 2 hour stage at 450 ° C. During this reduction protocol, the hydrogen flow is 1000 liters of H2 per liter of catalyst, The reaction is carried out at 265 ° C, under a total pressure of 12 MPa, an hourly volumetric velocity of 2 h "1 and a hydrogen flow of 1000 liters of H2 per liter of charge.The fractionation of the effluent makes it possible to collect a base oil as well as the residue and an average distillate cut-off of boiling point of 150-400 ° C (400 ° C which is excluded) and the light products.In these operating conditions the net conversion to compounds 400"(which they have a boiling point lower than 400 ° C) is 25% by weight and the yield in base oil is 75% by weight.

The characteristics of the obtained oil are reported in the following table.

The pour point of the diesel is -33 ° C This example shows all the interest there is in using a catalyst according to the invention, which allows to lower the pour point of the initial charge, in this case a hydrodecomposition residue, always maintaining a high viscosity index (VI).

Example 3 The zeolite of example 1 is used.

This zeolite NU-86 first undergoes a calcination called dry at 550 ° C under dry air flow for 9 hours. Then the solid obtained is subjected to four ion exchanges in a solution of NH4N03 ION, at approximately 100 ° C for 4 hours for each exchange. The solid thus obtained is referenced NH4-NU-86/1 and has a Si / Al ratio = 10.4 and a Na / Al ratio = 0.013. Its other physicochemical characteristics are grouped in Table 1. The zeolite NU-86 is then subjected to a treatment with a 6N nitric acid solution, at approximately 100 ° C, for 5 hours. The volume V of the nitric acid solution involved (in me) is equal to 10 times the weight of P of the dry NU-86 zeolite (V / P = 10).

At the exit of these treatments, the zeolite obtained was referenced NH4-NU-86/2. It has a global Si / Al ratio equal to 34, and an atomic ratio Na / Al equal to 0.005. These crystallographic and adsorption characteristics are reported in table 2, below.

Table 2 The zeolite is kneaded with alumina of type SB3 provided by the company Condéa. The kneaded dough is then extruded through a row with a diameter of 1.2 mm. The extrudates are then calcined at 500 ° C for 2 hours with air and then dry impregnated with a solution of platinum chloride tetramine [Pt (NH3) 4] Cl2, and finally calcined with air at 550 ° C. The content of platinum in the final catalyst thus obtained is 0.7% by weight and the content of zeolite expressed with respect to the mass group of the catalyst is 30% by weight.

Example 4 The catalyst was evaluated in a hydrodecomposition residue left from a vacuum distillate to prepare a base oil.

The characteristics of the load used are those reported below: The catalyst is pre-reduced in hydrogen at 450 ° C before catalytic testing in situ in the reactor. This reduction is effected by stopping from time to time. It consists of a stage at 150 ° C for 2 hours, then an increase in temperature up to 450 ° C at the speed of 1 ° C / min, then a 2 hour stage at 450 ° C. During this reduction protocol, the hydrogen flow is 1000 liters of H2 per liter of catalyst.

The reaction is carried out at 300 ° C, under a total pressure of 12 MPa, an hourly volumetric velocity of 1.8 h "1 and a hydrogen flow of 1000 liters of H2 per liter of charge, under these operating conditions the conversion Net in compounds 400"is 27% by weight and the yield in base oil is 73% by weight.

The characteristics of the obtained oil are reported in the following table This example shows all the interest there is in using a catalyst according to the invention, which allows lowering the pour point of the initial load, in this case a hydrodecomposition residue, always maintaining a high viscosity index (VI).

It is noted that in relation to this date, the best method known to the applicant to carry out the aforementioned invention, is that which is clear from the present description of the invention.

Having described the invention as above, the content of the following is claimed as property.

Claims (15)

1. Process for improving the pour point of a charge containing paraffins of more than 10 carbon atoms, characterized in that the charge to be treated is contacted with a catalyst based on zeolite NU-86 and at least one hydrodehydrogenating element , at a temperature between 170 and 500 ° C, a pressure between 1 and 250 bar and an hourly volumetric speed between 0.05 and 100 h_1, in the presence of hydrogen at a rate of 50 to 2000 1/1 of charge.

2. Process according to claim 1, characterized in that the catalyst is based on zeolite NU-86 containing silicon and at least one element T chosen from the group consisting of aluminum, iron, gallium and boron, in which at least part of the Element T was removed and has a global atomic Si / T ratio greater than 20.

3. Process according to claim 1, characterized in that the hydrodehydrogenating element belongs to group VIII.

4. Process according to claim 1, characterized in that the hydr-dehydrogenating element is a combination of at least one metal or a compound of group VI and at least one metal or a compound of group VIII.

5. Process according to one of claims 1 to 3, characterized in that the element T is aluminum.

6. Process according to one of claims 1 to 4, characterized in that the molar ratio Si / T is greater than 22.

7. Process according to one of claims 1 to 5, characterized in that the molar ratio Si / T is between 22 and 300.

8. Process according to one of claims 1 to 6, characterized in that the zeolite is partly in acid form.

9. Process according to claim 1, characterized in that the catalyst contains at least one matrix chosen from the elements of the group consisting of clays, magnesia, alumina, silica, titanium oxide, boron oxide, zirconia, aluminum phosphates, titanium phosphates , zirconium phosphates and silicas-aluminas and carbon.

10. Process according to one of the preceding claims, characterized in that the content of zeolite in the catalyst is between 0.5 and 99.9% by weight.

11. Process according to one of the preceding claims, characterized in that the filler has an initial boiling point greater than 175 ° C.

12. Process according to one of the preceding claims, characterized in that the filler has an initial boiling point of at least 280 ° C.

13. Process according to one of the preceding claims, characterized in that the filler is constituted by at least 80% by volume of compounds with a boiling point of at least 350 ° C.

14. Process according to one of the preceding claims, characterized in that the compound to be treated is present in a hydrocarbon charge chosen from the group formed by kerosenes, carborreactores, gasóleos, vacuum residues, hydrodecomposition residues, paraffins exits Fischer-Tropsch process , synthetic oils, middle distillates derived from FCC, bases for oils, polyalphadefines.

15. Process according to claim 13, characterized in that the product obtained, after the treatment of the heavy load by the catalyst based on zeolite NU-86, is fractionated in at least one cut that includes a middle distillate of low pour point, and a residue including the base oils of low pour point and high viscosity index.