EP4077595A1

EP4077595A1 - Use of a catalyst based on izm-2 with a low content of alkali metal for the isomerization of paraffinic feedstocks to middle distillates

Info

Publication number: EP4077595A1
Application number: EP20819768.1A
Authority: EP
Inventors: Christophe Bouchy
Original assignee: IFP Energies Nouvelles IFPEN
Current assignee: IFP Energies Nouvelles IFPEN
Priority date: 2019-12-17
Filing date: 2020-12-09
Publication date: 2022-10-26
Also published as: CN114929841A; FR3104603B1; JP2023506856A; US20230019569A1; BR112022010601A2; FR3104603A1; WO2021122198A1

Abstract

The present invention relates to a process for the isomerization of paraffinic feedstocks operating at a temperature of between 200°C and 500°C, at a total pressure of between 0.45 MPa and 7 MPa, at a hydrogen partial pressure of between 0.3 and 5.5 MPa, at an hourly space velocity of between 0.1 and 10 kilograms of feedstock introduced per kilogram of catalyst and per hour and using a catalyst comprising at least one metal from group VIII of the Periodic Table of the Elements, at least one matrix and at least one IZM-2 zeolite, said catalyst being characterized in that the total weight content of alkali metal and/or alkaline-earth metal elements is less than 200 ppm by weight relative to the total mass of said catalyst, preferably less than 150 ppm, preferably less than 100 ppm, preferably less than 90 ppm by weight, preferably less than 85 ppm by weight, more preferably less than 80 ppm by weight, very preferably less than 75 ppm by weight and more preferably still less than 70 ppm by weight and greater than 20 ppm by weight and preferably greater than 30 ppm by weight.

Description

USE OF AN IZM-2 BASED CATALYST WITH LOW ALKALINE CONTENT FOR ISOMERIZATION OF PARAFFINIC LOADS IN DISTILLATES

MEANS

Technical area

In order to meet the demand for middle distillates, that is to say in cuts that can be incorporated into the kerosene and / or gas oil pool, various methods of producing middle distillates based on the use of oil, natural gas or even renewable resources can be implemented.

Middle distillate bases can thus be produced from a paraffinic feed obtained from a feed obtained from renewable sources, and in particular from vegetable oils or animal fats, crude or having undergone a prior treatment, as well as mixtures of such fillers. In fact, said feeds derived from renewable sources contain chemical structures of the triglyceride or esters or free fatty acids type, the structure and the length of the hydrocarbon chain of the latter being compatible with the hydrocarbons present in the middle distillates. Said feeds from renewable sources produce, after hydrotreatment, paraffinic feeds, free of sulfur compounds and aromatic compounds. These paraffinic fillers are typically composed of linear paraffins having a number of carbon atoms between 9 and 25.

Middle Distillates can also be produced from natural gas, coal, or renewable sources through the Fischer-Tropsch synthesis process. In particular, the so-called low temperature Fischer-Tropsch synthesis using cobalt catalysts makes it possible to produce essentially linear paraffinic compounds having a very variable number of carbon atoms, typically from 1 to 100 carbon atoms or even more. Separation steps can make it possible to recover paraffinic charges having a number of carbon atoms between 9 and 25.

However, these middle distillate bases obtained after hydrotreatment of vegetable oils or after the low temperature Fischer-Tropsch synthesis process cannot generally be incorporated as such into the kerosene or gas oil pool, in particular because of insufficient cold properties. In fact, the high molecular weight paraffins which are linear or very weakly branched and which are present in these middle distillate bases lead to high pour points and therefore to freezing phenomena for uses at low temperature. For example, the pour point of a linear hydrocarbon containing 20 carbon atoms per molecule and the boiling point of which is equal to approximately 340 ° C, i.e. typically included in the middle distillate cut, is approximately + 37 ° C which makes its use impossible, the specification being -15 ° C for diesel. In order to reduce the values of the pour points, these linear paraffins or very little branched must be completely or partially eliminated.

This operation can be carried out by extraction with solvents such as propane or methyl ethyl ketone, this is called dewaxing with propane or with methyl ethyl ketone (MEK). However, these techniques are expensive, long and not always easy to implement.

The selective cracking of the longest linear paraffinic chains which leads to the formation of compounds of lower molecular weight, a part of which can be removed by distillation, constitutes a solution for reducing the values of the pour points. Given their shape selectivity, zeolites are among the most widely used catalysts for this type of process. The most widely used catalyst in the selective cracking dewaxing category is ZSM-5 zeolite, with structure type MFI, which has three-dimensional porosity, with medium pores (opening at 10 oxygen atoms 10MR). However, the cracking caused in such processes leads to the formation of large quantities of products of lower molecular weight, such as butane, propane, ethane and methane, which considerably reduces the yield of the desired products.

Another solution for improving the cold resistance consists in isomerizing the long linear paraffins while minimizing cracking as much as possible. This can be achieved by implementing a hydroisomerization process employing bifunctional catalysts. Bifunctional catalysts involve a Bronsted acid phase (eg zeolite) and a hydro / dehydrogenating phase (eg platinum) and generally a matrix (eg alumina). The appropriate choice of the acid phase helps promote isomerization of long linear paraffins and minimize cracking. Thus the shape selectivity of one-dimensional medium-pore zeolites (10MR) such as zeolites ZSM-22, ZSM-23, NU-10, ZSM-48, ZBM-30 makes their use particularly suitable for obtaining catalysts that are selective towards isomerization. . These examples illustrate the ongoing research carried out to develop ever more efficient catalysts for the isomerization of long linear paraffins, while minimizing the formation of cracking products by the use of appropriate zeolites.

In addition to the selectivity towards isomerization, the activity of the catalyst is also an important parameter. Increasing the activity of the catalyst improves the overall operation of the process from the point of view of its productivity or energy consumption. It is therefore desirable to develop catalysts that are the most active and the most selective as possible towards isomerization. The activity of bifunctional isomerization catalysts is largely dependent on the activity of the Bronsted acid phase (for example a zeolite), and therefore on its acidity, used in said catalysts. The acidity of the zeolitic phase is ultimately a function of the number of Bronsted acid sites in said phase and also of their strength (C. Marcilly, acid-base catalysis, volume 1, 2003). A means of increasing the activity of a bifunctional isomerization catalyst can therefore be to increase the acidity of the zeolitic phase involved in said catalyst by increasing the density of acid sites of the zeolitic phase, all other things being equal.

However, it is also well known that for a bifunctional isomerization catalyst, the ratio between the number of sites of the hydro / dehydrogenating phase and the number of sites of the acid phase has an impact on its isomerization selectivity. Too great a decrease in this ratio results in a decrease in the isomerization selectivity of the catalyst. This has for example been reported for the isomerization of n-decane on catalysts based on platinum and USY zeolite (F. Alvarez et al., Journal of Catalysis, 162, 1996, 179). More recently this has also been reported for the isomerization of n-hexadecane on catalysts based on platinum, USY zeolite or BEA zeolite (P. Mendes et al., AlChE Journal, 63, 7, 2017, 2864).

This has also been reported for the isomerization of n-hexadecane on catalysts based on platinum and ZSM-12 zeolite (S. Mehla et al., Journal of Porous Materials, 20, 2013, 1023). The isomerization selectivity of the catalysts increases when the number of acid sites of the ZSM-12 zeolite decreases (by increasing the Si / Al ratio of the zeolite used). This increase in selectivity is then done to the detriment of the activity of the catalyst. Another means of improving the isomerization selectivity of the catalyst may consist in partially neutralizing the Bronsted acid sites of the zeolite with cations (W. Wang et al., Catalysis Science and Technology, 9, 2019, 4162).

Increasing the activity of the bifunctional catalyst and maximizing its isomerization selectivity therefore require conflicting requirements in terms of the density of acid sites for the zeolite engaged in the catalyst.

Recently, the Applicant in its work has developed a new zeolite, the IZM-2 zeolite as described in application FR 2 918 050 A, as well as a process for converting long paraffinic charges having a number of atoms of carbon included between 9 and 25 using a catalyst comprising said zeolite IZM-2 as described in patent application FR 2 984 911 A, said process making it possible to improve the selectivity towards the production of middle distillates by limiting the production of products light crackers that cannot be incorporated into a diesel and / or kerosene pool. In the illustrative example of patent application FR 2 984 911 A, only an IZM-2 solid having an overall Si / Al molar ratio of 53 is used in the formulation of the catalyst. This overall Si / Al molar ratio was calculated from the results of characterization by X-ray fluorescence. The content of alkalis and / or alkaline-earth metals present in said catalyst is not disclosed.

Application FR 3 074 428 A teaches a process for preparing bifunctional catalysts using an IZM-2 zeolite. Said preparation process makes it possible both to preferentially localize the hydrogenating function on the surface and / or in the microporosity of the IZM-2 zeolite and to distribute the hydrogenating function homogeneously in the catalyst. The alkali and / or alkaline earth content in the catalysts of the examples is not disclosed.

The research work carried out by the applicant has led him to discover that, surprisingly, the use in a process for the isomerization of a paraffinic feedstock of a catalyst comprising at least one IZM-2 zeolite, said catalyst having a reduced alkali and / or alkaline-earth metal content makes it possible to improve the activity of the catalyst while retaining its selectivity for isomerization.

An object of the present invention relates to a process for the isomerization of paraffinic feedstocks, preferably obtained from hydrotreated vegetable and / or animal oils or from the low temperature Fischer-Trospch synthesis, said process using a bifunctional catalyst comprising at least one metal. from group VIII of the Periodic Table of the Elements, at least one matrix and at least one IZM-2 zeolite, said catalyst being characterized in that the total weight content of alkaline and / or alkaline earth elements is less than 200 ppm by weight relative to to the total mass of said catalyst, preferably less than 150 ppm, more preferably less than 100 ppm, preferably less than 90 ppm by weight, more preferably less than 85 ppm by weight, more preferably less than 80 ppm by weight , very preferably less than 75 ppm by weight and even more preferably less than 70 ppm by weight and greater than 20 ppm by weight and preferably greater than 30 ppm by weight. In the remainder of this document, the weight contents provided are considered relative to the dry mass of solid. The dry mass of solid corresponds to the mass of the solid after calcination in air for two hours at 1000 ° C. in a muffle furnace.

For the purposes of the present invention, the various embodiments presented can be used alone or in combination with each other, without limitation of combination when technically feasible.

In the sense of the present invention, the different ranges of parameters for a given step such as the pressure ranges and the temperature ranges can be used alone or in combination. For example, within the meaning of the present invention, a preferred pressure value range can be combined with a more preferred temperature value range.

Summary of the invention

The present invention relates to a process for the isomerization of paraffinic feeds operating at a temperature between 200 ° C and 500 ° C, at a total pressure between 0.45 MPa and 7 MPa, at a partial pressure of hydrogen between 0 , 3 and 5.5 MPa, at an hourly space velocity of between 0.1 and 10 kilogram of feed introduced per kilogram of catalyst and using a catalyst comprising and preferably consisting of at least one metal from group VIII of the classification periodic elements, at least one matrix and at least one IZM-2 zeolite, said catalyst being characterized in that the total weight content of alkali and / or alkaline earth elements is less than 200 ppm by weight relative to the total mass of said catalyst , preferably less than 150 ppm, more preferably less than 200 ppm by weight relative to the total mass of said catalyst, preferably less than 150 ppm, more preferably less than 100 ppm, of preferably less than 90 ppm by weight, more preferably less than 85 ppm by weight more preferably less than 80 ppm by weight, very preferably less than 75 ppm by weight and even more preferably less than 70 ppm by weight and greater than 20 ppm by weight and preferably greater than 30 ppm by weight.

An advantage of the present invention is to provide a process for the isomerization of a paraffinic feed using a catalyst comprising at least one IZM-2 zeolite, said catalyst having a reduced alkali and / or alkaline-earth content making it possible to improve the activity of the catalyst while retaining maximum isomerization selectivity. Throughout the remainder of the text, the total weight content of alkali and / or alkaline earth in said catalyst is measured by atomic absorption spectroscopy on a Flame Atomic Absorption Spectrometer (SAAF) VARIAN Spectr'AA 240FS device after dissolving the solid by mineralization of said solid by wet process. The term “mineralization of the solid” means the dissolution of said solid which is typically carried out in concentrated aqueous solutions of perchloric, hydrofluoric and hydrochloric acid. It can be carried out at temperature on a hot plate or by microwave. List of

Description of the embodiments

In accordance with the invention, the present invention relates to a process for the isomerization of paraffinic feeds operating at a temperature of between 200 ° C and 500 ° C, at a total pressure of between 0.45 MPa and 7 MPa, at a partial pressure of hydrogen between 0.3 and 5.5 MPa, at an hourly space velocity of between 0.1 and 10 kilogram of feed introduced per kilogram of catalyst and per hour and using a catalyst comprising at least one metal from the group VIII of the Periodic Table of the Elements, at least one matrix and at least one IZM-2 zeolite, said catalyst being characterized in that the total weight content of alkaline and / or alkaline earth elements is less than 200 ppm by weight relative to the total mass of said catalyst, preferably less than 150 ppm, more preferably less than 100 ppm by weight relative to the total mass of said catalyst, preferably less than 90 ppm by weight, preferably less ure at 85 ppm by weight more preferably less than 80 ppm by weight, very preferably less than 75 ppm by weight and even more preferably less than 70 ppm by weight and greater than 20 ppm by weight and preferably greater at 30 ppm by weight.

The isomerization process

In accordance with the invention, the isomerization process is carried out at a temperature between 200 ° C and 500 ° C, at a total pressure between 0.45 MPa and 7 MPa, at a partial pressure of hydrogen of between between 0.3 and 5.5 MPa, at an hourly space velocity of between 0.1 and 10 kilograms of feed introduced per kilogram of catalyst and per hour. Preferably, said process is carried out at a temperature between 200 and 450 ° C, and more preferably between 220 and 430 ° C, at a total pressure between 0.6 and 6 MPa, at a partial pressure of hydrogen. between 0.4 and 4.8 MPa, at an hourly space velocity advantageously between 0.2 and 7 h-1 and preferably between 0.5 and 5 h-1. According to the invention, the isomerization process comprises bringing a paraffinic feed into contact with at least said catalyst according to the invention present in a catalytic reactor.

The paraffins of said paraffinic filler have a number of carbon atoms of between 9 and 25, preferably between 10 and 25 and very preferably between 10 and 22. The paraffin content in said filler used in the process according to the invention is advantageously greater than 90% by weight, preferably greater than 95% by weight, even more preferably greater than 98% by weight. Within said paraffins, the percentage by weight of isoparaffins is less than 15%, preferably less than 10% and very preferably less than 5%.

According to a first embodiment, said paraffinic filler used in the process according to the invention can be produced from renewable resources.

Preferably, said paraffinic filler is produced from renewable resources chosen from vegetable oils, algal or algal oils, fish oils and fats of vegetable or animal origin, or mixtures of such fillers.

Said vegetable oils can advantageously be crude or refined, totally or in part, and obtained from plants chosen from rapeseed, sunflower, soya, palm, olive, coconut, copra, castor oil, cotton. , peanut, linseed and crambe oils and all oils obtained, for example, from sunflower or rapeseed by genetic modification or hybridization, this list not being exhaustive. Said animal fats are advantageously chosen from bacon and fats composed of residues from the food industry or from catering industries. Frying oils, various animal oils such as fish oils, tallow, lard can also be used.

The renewable resources from which the paraffinic filler used in the process according to the invention is produced essentially contain chemical structures of the triglyceride type that a person skilled in the art also knows under the name tri ester of fatty acids as well as fatty acids. free, whose fatty chains contain a number of carbon atoms between 9 and 25.

The structure and length of the hydrocarbon chain of the latter are compatible with the hydrocarbons present in gas oil and kerosene, ie the middle distillate cut. A tri fatty acid ester is thus composed of three fatty acid chains. These fatty acid chains in the form of a tri ester or in the form of free fatty acids have a number of unsaturations per chain, also called the number of carbon-carbon double bonds per chain, generally between 0 and 3 but which may be higher in particular for oils obtained from algae which generally have a number of unsaturations per chain of 5 to 6.

The molecules present in said renewable resources used in the present invention therefore exhibit a number of unsaturations, expressed per triglyceride molecule, advantageously between 0 and 18. In these charges, the level of unsaturation, expressed in number of unsaturations per hydrocarbon fatty chain is advantageously between 0 and 6.

Renewable resources generally also contain various impurities and in particular heteroatoms such as nitrogen. The nitrogen contents in vegetable oils are generally between 1 ppm and 100 ppm by weight approximately, depending on their nature. They can reach up to 1% by weight on specific loads.

Said paraffinic filler used in the process according to the invention is advantageously produced from renewable resources according to processes known to those skilled in the art. One possible route is the catalytic transformation of said renewable resources into deoxygenated paraffinic effluent in the presence of hydrogen and in particular hydrotreatment.

Preferably, said paraffinic feed is produced by hydrotreating said renewable resources. These processes for hydrotreating renewable resources are already well known and are described in numerous patents. By way of example, said paraffinic feedstock used in the process according to the invention can advantageously be produced, preferably by hydrotreatment then by gas / liquid separation, from said renewable resources such as for example in patent FR 2 910 483 or in patent FR 2 950895.

According to a second embodiment, said paraffinic feed used in the process according to the invention can also be a paraffinic feed produced by a process involving a step of upgrading by the Fischer-Tropsch route. In the Fischer-Tropsch process, synthesis gas (CO + H2) is catalytically converted into oxygenates and essentially linear hydrocarbons in gaseous, liquid or solid form. Said products obtained constitute the feed for the process according to the invention. Synthesis gas (CO + H2) is advantageously produced from natural gas, coal, biomass, any source of hydrocarbon compounds or a mixture of these sources. Thus, the paraffinic fillers obtained, according to a Fischer-Tropsch synthesis process, from a synthesis gas (C0 + H2) produced from renewable resources, natural gas or coal can be used in the process according to the invention. Preferably, said paraffinic filler produced by Fischer-Tropsch synthesis and used in the process according to the invention mainly comprises n-paraffins. Thus, said filler comprises an n-paraffin content greater than 60% by weight relative to the total mass of said filler. Said feed may also comprise a content of oxygenates preferably less than 10% by weight, a content of unsaturated products, that is to say preferably of olefinic products, preferably less than 20% by weight and an iso-content. paraffins preferably less than 10% by weight relative to the total mass of said filler.

Very preferably, said filler comprises an n-paraffin content greater than 70% by weight and even more preferably greater than 80% by weight relative to the total mass of said filler. The paraffins of said paraffinic filler have a number of carbon atoms between 9 and 25, preferably between 10 and 25 and very preferably between 10 and 22.

Preferably, said paraffinic feed produced by Fischer-Tropsch synthesis is free from heteroatomic impurities such as, for example, sulfur, nitrogen or metals.

Catalyst

The present invention relates to the use of a catalyst comprising, and preferably consisting of, at least one IZM-2 zeolite preferably containing silicon atoms and optionally aluminum atoms, at least one matrix and at least one metal from group VIII of the Periodic Table of the Elements, said catalyst being characterized in that the total weight content of alkali and / or alkaline earth elements in said catalyst is less than 200 ppm by weight relative to the total mass of said catalyst and greater than 20 ppm by weight.

Preferably, said catalyst has a total weight content of alkali and / or alkaline earth elements less than 150 ppm by weight relative to the total mass of said catalyst, preferably less than 100 ppm, preferably less than 90 ppm, preferably less at 85 ppm by weight, preferably less than 80 ppm by weight, more preferably less than 75 ppm by weight and even more preferably less than 70 ppm by weight and preferably greater than 30 ppm by weight. The alkaline and / or alkaline earth elements are preferably chosen from lithium, sodium, potassium, berylium, magnesium, barium, and calcium and preferably sodium and potassium and very preferably sodium.

Preferably, said catalyst has a total weight content of sodium elements less than 150 ppm by weight relative to the total mass of said catalyst, preferably less than 100 ppm, more preferably less than 90 ppm, preferably less than 85 ppm by weight. weight, preferably less than 80 ppm by weight, more preferably less than 75 ppm by weight and even more preferably less than 70 ppm by weight and greater than 20 ppm by weight and preferably greater than 30 ppm by weight .

Preferably, said catalyst does not include added alkali and / or alkaline earth elements, other than those associated with the zeolite and / or with the matrix used in said catalyst.

Said catalyst according to the invention advantageously comprises, and preferably consists of:

- from 1 to 90% by weight, preferably from 3 to 80% by weight and more preferably from 4 to 60% and even more preferably from 6 to 50% by weight of the IZM-2 zeolite relative to the total mass of the catalyst according to the invention,

- 0.01 and 5% by weight, preferably between 0.1 and 4% by weight and very preferably between 0.1 and 2% by weight of at least one metal from group VIII of the periodic table of elements, preferably platinum relative to the total mass of the catalyst,

- optionally from 0.01 to 2%, preferably from 0.05 to 1% by weight of at least one additional metal chosen from the group formed by the metals of groups NIA, IVA and VI IB relative to the total mass of the catalyst,

- optionally a sulfur content, preferably such that the ratio of the number of moles of sulfur to the number of moles of metal (s) of group VIII is between 0.3 and 3,

- With a total weight content of alkali and / or alkaline earth element of less than 200 ppm relative to the total mass of said catalyst, preferably less than 150 ppm, preferably less than 100 ppm, preferably less than 90 ppm by weight, preferably less than 85 ppm by weight more preferably less than 80 ppm by weight, very preferably less at 75 ppm by weight and even more preferably less than 70 ppm by weight and greater than 20 ppm by weight and preferably greater than 30 ppm by weight,

- at least one matrix, preferably alumina, providing 100% complement in the catalyst. Zeolite IZM-2

According to the invention, the catalyst comprises an IZM-2 zeolite. The IZM-2 zeolite has an X-ray diffraction pattern including at least the lines listed in Table 1. IZM-2 has a crystal structure.

Advantageously, the diffraction pattern is obtained by radiocrystallographic analysis using a diffractometer using the conventional powder method with the K _d radiation of copper (l = 1.5406 Å). From the position of the diffraction peaks represented by the angle 2Q, the _{characteristic reticular equidistances d hW} of the sample are calculated by the Bragg relationship. The measurement error A (d _{hk |} ) on d _hW is calculated using the Bragg relation as a function of the absolute error D (2Q) assigned to the measurement of 2Q. An absolute error D (2Q) equal to ± 0.02 ° is commonly accepted. The relative intensity l _rei assigned to each value of d _hki is measured from the height of the corresponding diffraction peak. The X-ray diffraction diagram of the IZM-2 zeolite contained in the catalyst according to the invention comprises at least the lines at the values of d _hki given in Table 1. In the column of d _hki , the mean values of the d hki are indicated. inter-reticular distances in Angstroms (Â). Each of these values must be affected by the measurement error A (d _hki ) between ± 0.6Â and ± 0.01 Â.

Table 1 represents the mean values of the d _hki and relative intensities measured on an X-ray diffraction diagram of the calcined crystalline solid IZM-2.

where FF = very strong; F = strong; m = medium; mf = medium low; f = weak; ff = very low.

The relative intensity l _rei is given in relation to a relative intensity scale where a value of 100 is assigned to the most intense line of the X-ray diffraction pattern: ff <15; £ 15 f <30; 30 £ mf <50; £ 50 <65; £ 65 F <85; FF ³ 85. Said IZM-2 solid advantageously has a chemical composition expressed on an anhydrous basis, in terms of moles of oxides, defined by the following general formula: X02: aY203: bM2 / nO, in which X represents at least one tetravalent element, Y represents at least one trivalent element and M is at least one alkali metal and / or one alkaline earth metal of valence n. In said formula given above, a represents the number of moles of Y203 and a is between 0 and 0.5, very preferably between 0 and 0.05 and even more preferably between and 0.0016 and 0, 02 and b represents the number of moles of M2 / nO and is between 0 and 1, preferably between 0 and 0.5 and even more preferably between 0.005 and 0.5. Preferably, X is chosen from silicon, germanium, titanium and the mixture of at least two of these tetravalent elements, very preferably X is silicon and Y is preferably chosen from aluminum, boron, iron, indium and gallium, very preferably Y is aluminum. M is preferably chosen from lithium, sodium, potassium, calcium, magnesium and the mixture of at least two of these metals and very preferably M is sodium. Preferably, X represents silicon, said crystallized solid IZM-2 is then an entirely silicic solid when the element Y is absent from the composition of said solid IZM-2. It is also advantageous to use as element X a mixture of several elements X, in particular a mixture of silicon with another element X chosen from germanium and titanium, preferably germanium. Thus, when the silicon is present as a mixture with another element X, said crystallized solid IZM-2 is then a crystallized metallosilicate exhibiting an X-ray diffraction pattern identical to that described in Table 1 when it is in its form. calcined. Even more preferably and in the presence of an element Y, X being silicon and Y being aluminum: said crystallized solid IZM-2 is then a crystallized aluminosilicate exhibiting an X-ray diffraction pattern identical to that described in Table 1 when in its calcined form.

More generally, said solid IZM-2 used in the support of the catalyst used in the process according to the invention advantageously exhibits a chemical composition expressed by the following general formula (I): X02: aY203: bM2 / nO : cR: dH20 in which R represents an organic species comprising two quaternary nitrogen atoms, X represents at least one tetravalent element, Y represents at least one trivalent element and M is an alkali metal and / or an alkaline earth metal of valence not ; a, b, c and d respectively representing the number of moles of Y203, M2 / nO, R and H20 and a is between 0 and 0.5, b is between 0 and 1, c is between 0 and 2 and d is between 0 and 2. This formula and the values taken by a, b, c and d are those for which said solid IZM-2 is preferably found in its calcined form.

More precisely, said solid IZM-2, in its crude synthetic form, advantageously exhibits a chemical composition expressed by the following general formula: X02: aY203: bM2 / nO: cR: dH20 (I) in which R represents an organic species comprising two quaternary nitrogen atoms, X represents at least one tetravalent element, Y represents at least one trivalent element and M is an alkali metal and / or an alkaline earth metal of valence n; a, b, c and d respectively representing the number of moles of Y203, M2 / nO, R and H20 and a is between 0 and 0.5, b is between 0 and 1, c is between 0.005 and 2 and preferably between 0.01 and 0.5, and d is between 0.005 and 2 and preferably between 0.01 and 1.

In formula (I) given above to define the chemical composition of said crystallized solid IZM-2 in its crude synthetic form, the value of a is between 0 and 0.5, very preferably between 0 and 0.05 and even more preferably between 0.0016 and 0.02. Preferably, b is between 0 and 1, very preferably b is between 0 and 0.5 and even more preferably b is between 0.005 and 0.5. The value of c is between 0.005 and 2, advantageously between 0.01 and 0.5. The value taken by d is between 0.005 and 2, preferably between 0.01 and 1.

In its crude synthetic form, that is to say directly resulting from the synthesis and prior to any calcination step (s) well known to those skilled in the art, said solid IZM-2 advantageously comprises at least the species organic R having two quaternary nitrogen atoms such as that described below or its decomposition products or its precursors. According to a preferred embodiment of the invention, in formula (I) given above, the element R is 1,6-bis (methylpiperidinium) hexane. Said organic species R, which acts as a structuring agent, can be eliminated by conventional means known from the state of the art, such as heat and / or chemical treatments.

A process for preparing the IZM-2 zeolite is taught in patent FR 2 918 050 B incorporated here by reference.

Advantageously, in the case where X is silicon and Y is aluminum, an aqueous mixture comprising at least one source of at least one SiO 2 oxide, optionally at least one source of at least one Al 2 O 3 oxide, is reacted. , optionally at least one source of at least one alkali metal and / or alkaline earth metal of valence n, and preferably at least one organic species R comprising two quaternary nitrogen atoms, the mixture preferably having the following molar composition:

SiO 2 / Al 2 O 3: at least 2, preferably at least 20, more preferably 60 to 600,

H2O / SI02: 1 to 100, preferably 10 to 70,

R / Si 02: 0.02 to 2, preferably from 0.05 to 0.5,

M2 / n0 / Si02: 0 to 1, preferably 0.005 and 0.5, where M is one or more alkali metal (s) and / or alkaline earth metal (s) chosen from lithium, sodium, potassium, calcium, magnesium and a mixture of at least two of these metals , preferably M is sodium. Advantageously, the element R is 1,6-bis (methylpiperidinium) hexane.

The Si / Al molar ratio of the IZM-2 zeolite can also be adjusted to the desired value by post-treatment methods of the IZM-2 zeolite obtained after synthesis. Such methods are known to those skilled in the art, and make it possible to carry out dealumination or desilication of the zeolite. Preferably, the Si / Al molar ratio of the IZM-2 zeolite forming part of the composition of the catalyst according to the invention is adjusted by an appropriate choice of the conditions for the synthesis of said zeolite.

Among the IZM-2 zeolites, it is usually preferred to use IZM-2 zeolites whose overall atomic ratio, silicon / aluminum (Si / Al), is greater than about 3 and more preferably IZM-2 zeolites whose Si / Al ratio. Al is between 5 and 200 and even more preferably between 10 and 150.

Also, according to a preferred embodiment of the process for preparing said crystallized solid IZM-2, an aqueous mixture comprising a silicon oxide, optionally alumina, 1,6-bis (methylpiperidinium) hexane dibromide and sodium hydroxide. According to another preferred embodiment of the process according to the invention, an aqueous mixture comprising a silicon oxide, optionally alumina and 1,6-bis (methylpiperidinium) hexane dihydroxide is reacted.

The process for preparing said crystallized solid IZM-2 advantageously consists in preparing an aqueous reaction mixture called a gel and containing at least one source of at least one oxide X02, optionally at least one source of at least one oxide Y203, at least one organic species R, optionally at least one source of at least one alkali metal and / or alkaline earth metal of valence n. The amounts of said reagents are advantageously adjusted so as to confer on this gel a composition allowing its crystallization in crystallized solid IZM-2 in its crude synthetic form of general formula (I) X02: aY203: bM2 / nO: cR: dH20, where a, b, c and d meet the criteria defined above when c and d are greater than 0. The gel is then subjected to a hydrothermal treatment until said crystallized solid IZM-2 is formed. The gel is advantageously placed under hydrothermal conditions under an autogenous reaction pressure, optionally by adding gas, for example nitrogen, at a temperature between 120 ° C and 200 ° C, preferably between 140 ° C and 180 ° C, and even more preferably between 160 and 175 ° C until the formation of crystals of solid IZM-2 under its crude synthetic form. The time required to obtain crystallization generally varies between 1 hour and several months depending on the composition of the reagents in the gel, the stirring and the reaction temperature. Preferably, the crystallization time varies between 2 hours and 21 days. The reaction is generally carried out with stirring or in the absence of stirring, preferably in the presence of stirring.

It may be advantageous to add seeds to the reaction mixture in order to reduce the time required for crystal formation and / or the total crystallization time. It may also be advantageous to use seeds in order to promote the formation of said crystallized solid IZM-2 to the detriment of impurities. Such seeds advantageously comprise crystalline solids, in particular crystals of solid IZM-2. The seed crystals are generally added in a proportion of between 0.01 and 10% of the mass of the oxide X02 used in the reaction mixture.

At the end of the hydrothermal treatment step leading to the crystallization of said solid IZM-2, the solid phase is advantageously filtered, washed, dried and then calcined. The calcination step is advantageously carried out by one or more heating steps carried out at a temperature between 100 and 1000 ° C, preferably between 400 and 650 ° C, for a period of between a few hours and several days, preferably between 3 hours and 48 hours. Preferably, the calcination is carried out in two consecutive heating steps.

At the end of said calcination step, said solid IZM-2 obtained is advantageously that exhibiting the X-ray diffraction diagram including at least the lines listed in Table 1. It is devoid of water as well as of the species. organic R present in the solid IZM-2 in its crude synthetic form. After said calcination step, the IZM-2 zeolite can typically contain from 2000 to 8000 ppm of alkali and / or alkaline earth element and preferably of sodium.

After calcination, in order to reduce the alkali and / or alkaline-earth and preferably sodium content, in said zeolite, the solid IZM-2 entering into the composition of the support of the catalyst according to the invention is advantageously washed with at least one treatment with a solution of at least one ammonium salt so as to obtain the ammonium form of the solid IZM-2. The M / Y atomic ratio is generally advantageously less than 0.1 and preferably less than 0.05 and even more preferably less than 0.01. This washing step can be carried out at any step in the preparation of the catalyst or catalyst support, that is to say after the step of preparing the IZM-2 solid, after the step of shaping the solid. IZM-2, or even after the step of introducing the hydro- metal dehydrogenating. Preferably the washing step is carried out before the step of shaping the solid IZM-2. The washing step is preferably carried out by immersing the solid with stirring in an aqueous solution of at least one ammonium salt. The ammonium salt can be chosen from ammonium nitrate NH4N03, ammonium chloride NH4Cl, ammonium hydroxide NH40H, ammonium bicarbonate NH4HCO3, ammonium acetate NH4H3C202 or else sulphate of Ammonium (NH4) 2SO4. The period of immersion of the solid in the solution can typically vary from 15 minutes to several hours. The concentration of ammonium salt (s) in the solution is typically between 0.1 mol per liter and 10 moles per liter. The washing is preferably carried out at a temperature between room and 100 ° C. The ratio between the volume of solution involved (in ml) and the mass of zeolite involved (in grams) is preferably between 1 and 100. To reduce the content of alkali and / or alkaline earth and preferably sodium to the desired level it it may be necessary to repeat the washing step several times. At the end of the last washing, the solid is filtered off, washed with deionized water and then dried. Finally, the IZM-2 zeolite is calcined in order to obtain it in its proton form. The calcination conditions are typically the same as those used to calcine the solid at the end of the hydrothermal treatment step.

After washing, the zeolite can typically contain less than 200 ppm and preferably more than 20 ppm, or even more than 30 ppm of alkali and / or alkaline earth element and preferably of sodium.

Matrix

According to the invention, the catalyst comprises at least one matrix. Said matrix can advantageously be amorphous or crystalline.

Preferably, said matrix is advantageously chosen from the group formed by alumina, silica, silica-alumina, clays, titanium oxide, boron oxide and zirconia, taken alone or as a mixture or else one can also choose the aluminates. Preferably, alumina is used as a matrix. Preferably, said matrix contains alumina in all its forms known to those skilled in the art, such as, for example, aluminas of the alpha, gamma, eta, delta type. Said aluminas differ by their specific surface and their pore volume. The alkali and / or alkaline earth content of the matrix is variable and depends on the method of obtaining said matrix as is well known for alumina for example (Handbook of Porous Solids, 2008, Wiley-VCH chapter 4.7.2 .). The support for the catalyst used in the invention comprises and preferably consists of said matrix and said IZM-2 zeolite.

The content of alkali and / or alkaline earth element in the matrix can advantageously be adjusted by any method known to those skilled in the art to obtain a catalyst in accordance with the invention. The matrix or the precursor of the matrix can thus be washed by bringing into contact an aqueous solution whose pH is less than or equal to the zero charge point of said matrix, as illustrated for an alumina matrix in Catalysis Supports and Supported Catalysts, Butterworth Publishers (1987). By way of illustration, boehmite can be washed by contacting said solid with an aqueous solution of ammonium nitrate. The duration of immersion of the solid in the solution can typically vary from 15 minutes to several hours. The concentration of ammonium salt (s) in the solution is typically between 0.1 mol per liter and 10 moles per liter. Washing is preferably carried out at a temperature between room and 100 ° C. The ratio between the volume of solution engaged (in ml) and the mass of the boehmite engaged (in grams) is preferably between 1 and 100. To reduce the alkali and / or alkaline earth content to the desired level it may be necessary to necessary to repeat the washing step several times. After the last washing, the solid is filtered, washed with deionized water, then dried and calcined.

When it contains alkaline and / or alkaline earth elements, the matrix can typically contain less than 200 ppm and preferably more than 20 ppm, or even more than 30 ppm, of alkali and / or alkaline earth element and preferably of sodium. .

In accordance with the invention, the catalyst comprises at least one metal from group VIII preferably chosen from iron, cobalt, nickel, ruthenium, rhodium, palladium, osmium, iridium and platinum, of preferably chosen from the noble metals of group VIII, very preferably chosen from palladium and platinum and even more preferably platinum is chosen.

Preferably, said catalyst comprises a group VIII metal content of between 0.01 and 5% by weight relative to the total mass of said catalyst and preferably of between 0.1 and 4% by weight.

In the case where said catalyst comprises at least one noble metal from group VIII, the noble metal content of said catalyst is advantageously between 0.01 and 5% by weight, preferably between 0.1 and 4% by weight and preferably between 0.1 and 4% by weight. very preferably between 0.1 and 2% by weight relative to the total mass of said catalyst. The catalyst of the invention can also advantageously contain at least one metal chosen from metals of groups II IA, IVA and VI IB chosen from gallium, indium, tin and rhenium. In this case, the metal content chosen from the metals of groups NIA, IVA and Vil B is preferably between 0.01 and 2%, preferably between 0.05 and 1% by weight relative to the total mass of said catalyst. .

The dispersion of the metal (s) of group VIII, determined by chemisorption, for example by H2 / 02 titration or by chemisorption of carbon monoxide, is between 10% and 100%, preferably between 20% and 100% and even more preferably between 30% and 100%. The macroscopic distribution coefficient of the metal (s) of group VIII, obtained from its (their) profile determined by Castaing microprobe, defined as the ratio of the concentrations of the metal (s) of group VIII to core of the grain with respect to the edge of this same grain is between 0.7 and 1.3, preferably between 0.8 and 1.2. The value of this ratio, close to 1, testifies to the homogeneity of the distribution of the metal (s) from group VIII in the catalyst.

The catalyst according to the invention can advantageously be prepared according to all the methods well known to those skilled in the art.

Formatting

Advantageously, the various constituents of the support or of the catalyst can be shaped by mixing step to form a paste then extrusion of the paste obtained, or else by mixing powders then pelletizing, or else by any other known agglomeration process. a powder containing alumina. The supports thus obtained can be in different shapes and sizes. Preferably, the shaping is carried out by mixing and extrusion.

During the shaping of the support by mixing and then extrusion, said IZM-2 zeolite can be introduced during the dissolution or suspension of alumina compounds or alumina precursors such as bohemite for example. Said IZM-2 zeolite can be, without this being limiting, for example in the form of powder, ground powder, suspension or suspension which has undergone a deagglomeration treatment. Thus, for example, said zeolite can advantageously be placed in suspension, acidified or not, at a concentration adjusted to the final IZM-2 content targeted in the catalyst according to the invention. This suspension commonly called a slip is then mixed with the alumina compounds or alumina precursors. Furthermore, the use of additives can advantageously be implemented to facilitate shaping and / or improve the final mechanical properties of the supports, as is well known to those skilled in the art. By way of example of additives, mention may in particular be made of cellulose, carboxymethyl-cellulose, carboxy-ethyl-cellulose, tall oil (tall oil), xanthan gums, surfactants, agents. flocculants such as polyacrylamides, carbon black, starches, stearic acid, polyacrylic alcohol, polyvinyl alcohol, biopolymers, glucose, polyethylene glycols, etc.

Water can advantageously be added or removed to adjust the viscosity of the paste to be extruded. This step can advantageously be carried out at any stage of the mixing step.

To adjust the solid matter content of the paste to be extruded in order to make it extrudable, it is also possible to add a predominantly solid compound and preferably an oxide or a hydrate. A hydrate is preferably used and even more preferably an aluminum hydrate is used. The loss on ignition of this hydrate is advantageously greater than 15%.

The extrusion of the paste resulting from the kneading step can advantageously be carried out by any conventional tool, available commercially. The paste resulting from the mixing is advantageously extruded through a die, for example using a piston or a single or twin extrusion screw. The extrusion can advantageously be carried out by any method known to those skilled in the art.

The catalyst supports according to the invention are generally in the form of cylindrical or polylobed extrudates such as bilobed, trilobed, polylobed in straight or twisted shape, but can optionally be manufactured and used in the form of crushed powders, tablets, etc. rings, balls and / or wheels. Preferably, the supports for the catalyst according to the invention are in the form of spheres or extrudates. Advantageously, the support is in the form of extrudates with a diameter of between 0.5 and 5 mm and more particularly between 0.7 and 2.5 mm. The shapes may be cylindrical (which may or may not be hollow) and / or twisted cylindrical and / or multilobed (2, 3, 4 or 5 lobes for example) and / or rings. The multilobed form is advantageously used in a preferred manner.

Drying

The support thus obtained can then be subjected to a drying step. Said drying step is advantageously carried out by any technique known to those skilled in the art. Preferably, the drying is carried out under air flow. Said drying can also be carried out under a flow of any oxidizing, reducing or inert gas. Preferably, the drying is advantageously carried out at a temperature between 50 and 180 ° C, preferably between 60 and 150 ° C and very preferably between 80 and 130 ° C.

Calcination

Said support, optionally dried, then preferably undergoes a calcination step.

Said calcination step is advantageously carried out in the presence of molecular oxygen, for example by carrying out an air sweep, at a temperature advantageously greater than 200 ° C and less than or equal to 1100 ° C. Said calcination step can advantageously be carried out in a traversed bed, in a lickbed bed or in a static atmosphere. For example, the furnace used can be a rotary rotary furnace or be a vertical furnace with radial traversed layers. Preferably, said calcination step is carried out between more than one hour at 200 ° C to less than one hour at 1100 ° C. Calcination can advantageously be carried out in the presence of water vapor and / or in the presence of an acidic or basic vapor. For example, the calcination can be carried out under partial pressure of ammonia.

Post-calcination treatments can optionally be carried out, so as to improve the properties of the support, in particular the textural properties.

Thus, the support of the catalyst according to the present invention can be subjected to a hydrothermal treatment in a confined atmosphere. The term “hydrothermal treatment in a confined atmosphere” means treatment by autoclaving in the presence of water at a temperature above room temperature, preferably above 25 ° C, preferably above 30 ° C.

During this hydrothermal treatment, the support can advantageously be impregnated, prior to its passage in the autoclave (autoclaving being carried out either in vapor phase or in liquid phase, this vapor or liquid phase of the autoclave possibly being acidic. or not). This impregnation, prior to autoclaving, may advantageously be acidic or not. This impregnation, prior to autoclaving, can advantageously be carried out dry or by immersing the support in an acidic aqueous solution. By dry impregnation is meant bringing the support into contact with a volume of solution less than or equal to the total pore volume of the support. Preferably, the impregnation is carried out dry. The autoclave is preferably an autoclave with a rotating basket such as that defined in patent application EP 0 387 109 A. The temperature during autoclaving can be between 100 and 250 ° C for a period of time between 30 minutes and 3 hours.

The mixture of the matrix and the shaped IZM-2 zeolite constitutes the catalyst support. The alkali and / or alkaline earth content of the support can also be adjusted by any method known to those skilled in the art to obtain a catalyst in accordance with the invention.

Preferably, washing treatments can also be carried out in order to reduce the alkali and / or alkaline earth content of the support. The operating conditions for washing are typically the same as those described for washing the zeolite. The support is then again calcined after washing, preferably under the same conditions as those described for washing the zeolite.

Deposition of the metallic phase

For the deposition of the metal from group VIII of the Periodic Table of the Elements, all the deposition techniques known to those skilled in the art and all the precursors of such metals may be suitable. Dry impregnation deposition techniques or in excess of a solution containing the metal precursors can be used, in the presence of competitors or not. The introduction of the metal can be carried out at any stage of the preparation of the catalyst: on the IZM-2 zeolite and / or on the matrix, in particular before the shaping step, during the shaping step, or after the shaping step, on the catalyst support. Preferably, the deposition of the metal takes place after the shaping step.

The control of certain parameters implemented during the deposition, in particular the nature of the precursor of the group VIII metal (s) used (s), makes it possible to orient the deposition of the said metal (s) ( ux) mainly on the matrix or on the zeolite.

Thus, to introduce the metal (s) from group VIII, preferably platinum and / or palladium, mainly on the matrix, an anion exchange can be carried out with hexachloroplatinic acid and / or hexachloropalladic acid, preferably in the presence of a competing agent, for example hydrochloric acid, the deposition generally being followed by calcination, for example at a temperature between 350 and 550 ° C and for a period of between 1 and 4 hours. With such precursors, the metal (s) of group VIII is (are) deposited mainly on the matrix and the said metal (s) present (s) a good dispersion and a good macroscopic distribution across the grain of catalyst. It is also possible to envisage depositing the metal (s) from group VIII, preferably platinum and / or palladium, by cation exchange so that the said metal (s) are themselves (in ) t deposited mainly on the zeolite. Thus, in the case of platinum, the precursor can for example be chosen from:

- ammonia compounds such as the platinum (II) tetramine salts of formula Pt (NH3) 4X2, the platinum (IV) hexamine salts of formula Pt (NH3) 6X4; halopentamine platinum (IV) salts of formula (PtX (NH3) 5) X3; the N-tetrahalodiamine platinum salts of formula PtX4 (NH3) 2; and

- halogenated compounds of formula H (Pt (acac) 2X);

X being a halogen chosen from the group formed by chlorine, fluorine, bromine and iodine, X preferably being chlorine, and "acac" representing the acetylacetonate group (of gross formula C5H702), derived from acetylacetone . With such precursors, the metal (s) of group VIII is (are) deposited (s) mainly on the zeolite and the said metal (s) present (s) a good dispersion and a good macroscopic distribution across the grain of catalyst.

The impregnation solution can advantageously also comprise at least one ammonium salt chosen from ammonium nitrate NH4N03, ammonium chloride NH4Cl, ammonium hydroxide NH40H, ammonium bicarbonate NH4HC03, acetate ammonium NH4H3C202 alone or as a mixture, the molar ratio between the ammonium salt and the noble metal of the precursor being between 0.1 and 400.

In the case where the catalyst of the invention also contains at least one metal chosen from the metals of groups NIA, IVA and VI IB, all the techniques for depositing such a metal known to those skilled in the art and all the precursors such metals may be suitable.

The metal (s) from group VIII and that (those) from groups NIA, IVA and VII B can be added, either separately or simultaneously in at least one unitary step. When at least one metal from groups NIA, IVA and VII B is added separately, it is preferable that it is added after the metal from group VIII.

The additional metal chosen from metals from groups NIA, IVA and VII B can be introduced via compounds such as, for example, chlorides, bromides and nitrates of metals from groups NIA, IVA and VII B. For example in in the case of indium, nitrate or chloride is advantageously used and in the case of rhenium, perrhenic acid is advantageously used. The additional metal chosen from the metals of groups NIA, IVA and VIIB can also be introduced in the form of at least one compound organic chosen from the group consisting of complexes of said metal, in particular polyketone complexes of the metal and hydrocarbylmetals such as alkyls, cycloalkyls, aryls, alkylaryls and arylalkyls of metals. In the latter case, the introduction of the metal is advantageously carried out using a solution of the organometallic compound of said metal in an organic solvent. Organohalogen compounds of the metal can also be employed. As organic compounds of metals, there may be mentioned in particular tetrabutyltin, in the case of tin, and triphenylindium, in the case of indium.

If the additional metal chosen from the metals of groups NIA, IVA and VII B is introduced before the metal of group VIII, the compound of the metal NIA, IVA and / or VIIB used is generally chosen from the group consisting of the halide, the metal nitrate, acetate, tartrate, carbonate and oxalate. The introduction is then advantageously carried out in aqueous solution. But it can also be introduced using a solution of an organometallic compound of the metal, for example tetrabutyltin. In this case, before proceeding with the introduction of at least one metal from group VIII, calcination in air will be carried out.

In addition, intermediate treatments such as, for example, calcination and / or reduction can be applied between the successive deposits of the different metals.

Before its use in an isomerization process, the catalyst according to the invention is preferably reduced. This reduction step is advantageously carried out by treatment under hydrogen at a temperature of between 150 ° C and 650 ° C and a total pressure of between 0.1 and 25 MPa. For example, a reduction consists of a plateau at 150 ° C for two hours then a rise in temperature to 450 ° C at a rate of 1 ° C / min then a plateau of two hours at 450 ° C; throughout this reduction step, the hydrogen flow rate is 1000 normal m3 of hydrogen per tonne of catalyst and the total pressure kept constant at 0.2 MPa. Any ex-situ reduction method can advantageously be envisaged. A prior reduction of the final catalyst ex situ, under a stream of hydrogen, can be carried out, for example at a temperature of 450 ° C. to 600 ° C., for a period of 0.5 to 4 hours.

Said catalyst also advantageously comprises sulfur. In the case where the catalyst of the invention contains sulfur, the latter can be introduced at any stage of the preparation of the catalyst: before or after the shaping stage, and / or drying and / or calcination, before and / or after the introduction of the metal (s) mentioned above, or alternatively by sulfurization in situ and / or ex situ before the catalytic reaction. In the case of in situ sulfurization, the reduction, if the catalyst has not been reduced beforehand, takes place before the sulfurization. In the case of ex situ sulfurization, the reduction and then the sulfurization are also carried out. The sulfurization is preferably carried out in the presence of hydrogen using any sulfurizing agent well known to those skilled in the art, such as, for example, dimethyl sulfide or hydrogen sulfide.

The catalysts according to the invention come in different shapes and sizes. They are generally used in the form of cylindrical and / or polylobed extrudates such as bilobed, trilobed, polylobed of straight and / or twisted shape, but can optionally be manufactured and employed in the form of crushed powders, tablets, rings, balls and / or wheels. Preferably, the catalysts used in the process according to the invention have the form of spheres or extrudates. Advantageously, the catalyst is in the form of extrudates with a diameter of between 0.5 and 5 mm and more particularly between 0.7 and 2.5 mm. The shapes may be cylindrical (which may or may not be hollow) and / or twisted cylindrical and / or multilobed (2, 3, 4 or 5 lobes for example) and / or rings. The multilobed form is advantageously used in a preferred manner. The deposition of the metal does not change the shape of the support.

The following examples illustrate the invention without, however, limiting its scope.

EXAMPLES

Example 1: synthesis of the IZM-2 zeolite

The IZM-2 zeolite was synthesized in accordance with the teaching of patent FR 2 918 050 B. A colloidal suspension of silica known under the trade name Ludox HS-40 marketed by Aldrich, is incorporated into a solution composed of soda (Prolabo). , 1.6bis (methylpiperidinium) hexane dibromide structuring agent, aluminum hydroxide (Aldrich) and deionized water. The molar composition of the mixture is as follows: 1 SiO 2; 0.0042 AI203; 0.1666 Na20; 0.1666 1.6bis (methylpiperidinium) hexane; 33.3333 H2O. The mixture is stirred vigorously for half an hour. The mixture is then transferred, after homogenization, into an autoclave of the PARR type. The autoclave is heated for 5 days at 170 ° C. with stirring in the spit (30 revolutions / min). The product obtained is filtered, washed with deionized water to reach a neutral pH and then dried overnight at 100 ° C. in an oven. The solid is then introduced into a muffle furnace to be calcined there in order to remove the structuring agent. The calcination cycle includes a rise in temperature up to 200 ° C, a plateau at this temperature of two hours, a rise in temperature up to 550 ° C followed by a plateau of eight hours at this temperature and finally a return at room temperature. The temperature rises are carried out with a ramp of 2 ° C / min. The The solid thus obtained after calcination contains a sodium content measured by atomic absorption of 3695 ppm.

To reduce the sodium content, the solid thus obtained is then refluxed for 2 hours in an aqueous solution of ammonium nitrate (10 ml of solution per gram of solid, ammonium nitrate concentration of 3 M). This refluxing step is carried out four times with a fresh solution of ammonium nitrate, then the solid is filtered, washed with deionized water and dried in an oven overnight at 100 ° C. Finally, to obtain the zeolite in its acid form (protonated H +), a calcination step is carried out at 550 ° C for ten hours (temperature rise ramp of 2 ° C / min) in a crossed bed in dry air (2 normal liters per hour and per gram of solid). The solid thus obtained was analyzed by X-ray diffraction and identified as being constituted by zeolite IZM-2. The solid thus obtained contains a sodium content measured by atomic absorption of 142 ppm.

The IZM-2 / alumina support is obtained by mixing and extruding the IZM-2 zeolite prepared according to Example 1 with a first batch of boehmite supplied by the company AXENS containing 287 ppm by weight of sodium. The kneaded dough is extruded through a trilobed die with a diameter of 1.8 mm. After drying in an oven overnight at 110 ° C, the extrudates are calcined at 550 ° C for two hours (temperature rise ramp of 5 ° C / min) in a crossed bed in dry air (2 normal liters per hour and per gram solid). The support does not undergo a washing step. The weight content of the IZM-2 zeolite in the support after calcination is 24% by weight. The sodium content in the support measured by atomic absorption is 252 ppm by weight.

Example 3 (not in accordance with the invention): preparation of an isomerization catalyst A.

Catalyst A is a catalyst comprising an IZM-2 zeolite, platinum, and an alumina matrix. This catalyst is prepared by dry impregnation of the IZM-2 / alumina support prepared according to Example 2 with an aqueous solution containing platinum nitrate tetramine Pt (NH3) 4 (NO3) 2. Typically 20 grams of support is used, which is dry impregnated in a bezel. After impregnation, the solid is left to mature for at least five hours in laboratory air then left to dry overnight in an oven at 110 ° C and a calcination step is finally carried out under a flow of dry air (1 normal liter per hour and per hour. gram of solid) in a tube furnace under the following conditions: temperature rise to ambient to 150 ° C at 5 ° C / min, hold for one hour at 150 ° C,

- rise from 150 ° C to 450 ° C at 5 ° C / min,

- one hour level at 450 ° C,

- descent to ambient.

The Pt content measured by FX on the calcined catalyst is 0.3% by weight relative to the total mass of said catalyst, its distribution coefficient measured by Castaing microprobe of 0.6. The catalyst obtained does not undergo a washing step with an ammonium nitrate solution. The sodium content by weight in the catalyst measured by atomic absorption is 255 ppm.

The textural properties of catalyst A were characterized by nitrogen porosimetry at 196 ° C on a Micromeritics ASAP 2010 device. Before nitrogen adsorption, the solid is degassed under vacuum at 90 ° C for one hour then at 350 ° C. for four hours. The total pore volume corresponds to the volume of nitrogen adsorbed at a relative pressure of 0.97. The specific surface of the solid is calculated by the BET method and the median pore diameter calculated according to the BJH adsorption model corresponds to the diameter for which half the volume of nitrogen is adsorbed. Catalyst A has a specific surface area of 294 m ² / g, a total pore volume of 0.64 ml / g and a median diameter of 14 nm.

This support is obtained by washing the first IZM-2 / alumina support described in Example 2. The IZM-2 / alumina support described in Example 2 is washed with an aqueous solution of ammonium nitrate. The support is placed in contact with an aqueous solution of ammonium nitrate in an Erlenmeyer flask on a stirring table for 24 hours. The volume of solution is set at 8 ml per gram of support and the ammonium nitrate concentration is set at 0.15 M. After 24 hours the solution is withdrawn and then the solid is rinsed with twice the exchange volume d distilled water then left to dry overnight in an oven at 110 ° C. The solid is then calcined in a crossed bed under dry laboratory air (1 normal liter per hour and per gram of solid) in a tube furnace under the following conditions:

- temperature rise to ambient to 150 ° C at 5 ° C / min,

- one hour level at 150 ° C,

- rise from 150 to 250 ° C at 5 ° C / min,

- level of one hour at 250 ° C, - rise from 250 to 350 ° C at 5 ° C / min,

- one hour level at 350 ° C,

- rise from 350 to 520 ° C at 5 ° C / min,

- two hour level at 520 ° C,

- drop to ambient temperature.

The sodium content in the support measured by atomic absorption is 40 ppm by weight.

Example 5 (according to the invention): preparation of an isomerization catalyst B.

Catalyst B is a catalyst comprising an IZM-2 zeolite, platinum, and an alumina matrix. This catalyst is prepared by dry impregnation of the IZM-2 / alumina support prepared according to Example 4 with an aqueous solution containing platinum nitrate tetramine Pt (NH3) 4 (NO3) 2. Typically 20 grams of carrier is used which is dry impregnated in a bezel. After impregnation, the solid is left to mature for at least five hours in laboratory air then left to dry overnight in an oven at 110 ° C and a calcination step is finally carried out under a flow of dry air (1 normal liter per hour and per hour. gram of solid) in a tube furnace under the following conditions:

- temperature rise to ambient to 150 ° C at 5 ° C / min;

- one hour hold at 150 ° C;

- rise from 150 ° C to 450 ° C at 5 ° C / min;

- one hour hold at 450 ° C;

- descent to ambient.

The Pt content measured by FX on the calcined catalyst is 0.3% by weight relative to the total mass of catalyst, its distribution coefficient measured by Castaing microprobe of 0.5. The catalyst obtained does not undergo a washing step with an ammonium nitrate solution. The sodium content in the catalyst measured by atomic absorption is 42 ppm by weight.

The textural properties of catalyst B were characterized by nitrogen porosimetry at 196 ° C on a Micromeritics ASAP 2010 device. Before nitrogen adsorption, the solid is degassed under vacuum at 90 ° C for one hour then at 350 ° C. for four hours. The total pore volume corresponds to the volume of nitrogen adsorbed at a relative pressure of 0.97. The specific surface of the solid is calculated by the BET method and the median pore diameter calculated according to the BJH adsorption model corresponds to the diameter for which half of the volume of nitrogen is adsorbed. Catalyst B has a specific surface of 300 m ² / g, a total pore volume of 0.65 ml / g and a median diameter of 13 nm.

Catalyst C is a catalyst comprising an IZM-2 zeolite, platinum, and an alumina matrix. Catalyst D is a catalyst comprising an IZM-2 zeolite, platinum, and an alumina matrix. This catalyst is prepared by impregnating in excess of the IZM-2 / alumina support prepared according to Example 2 with an aqueous solution containing hexachloroplatinic acid. The concentration of hexachloroplatinic acid in the solution is 2.55 10-3 mol / l.

20 grams of support are used, the pore volume of which is filled with distilled water and the solid is allowed to mature for one hour at room temperature. The solid is then immersed in 80 ml of a hydrochloric acid HCl solution of concentration 3.52 10-1 mol / l in an Erlenmeyer flask then the whole is stirred on a stirring table (100 revolutions / min ) at room temperature for one hour. The hydrochloric acid solution is then withdrawn then the solid is immersed in 80 ml of the hexachloroplatinic acid solution described above, then the whole is stirred on a stirring table (100 revolutions / min) at room temperature for 24 hours. The impregnation solution is then drawn off and the solid is rinsed with 160 ml of distilled water. The solid is then placed to dry in a ventilated oven overnight at 110 ° C. and a calcination step is finally carried out under a flow of dry air (2 normal liters per hour and per gram of solid) in a tube furnace under the conditions following:

- temperature rise to ambient to 500 ° C at 5 ° C / min,

- two hour hold at 500 ° C,

- descent to ambient.

The Pt content measured by FX on the calcined catalyst is 0.2% by weight relative to the total mass of catalyst, its distribution coefficient measured by Castaing microprobe of 1.0. The catalyst obtained does not undergo a washing step with an ammonium nitrate solution. The sodium content in the catalyst measured by atomic absorption is 180 ppm by weight.

The textural properties of catalyst C were characterized by nitrogen porosimetry at 196 ° C on a Micromeritics ASAP 2010 device. Before nitrogen adsorption, the solid is degassed under vacuum at 90 ° C for one hour then at 350 ° C. for four hours. The total pore volume corresponds to the volume of nitrogen adsorbed at a relative pressure of 0.97. The specific surface of the solid is calculated by the BET method and the median pore diameter calculated according to the BJH adsorption model corresponds to the diameter for which half the volume of nitrogen is adsorbed. Catalyst C has a specific surface area of 292 m ² / g, a total pore volume of 0.65 ml / g and a median diameter of 14 nm.

Example 7 (according to the invention): preparation of an isomerization catalyst D.

Catalyst D is a catalyst comprising an IZM-2 zeolite, platinum, and an alumina matrix. Catalyst D is a catalyst comprising an IZM-2 zeolite, platinum, and an alumina matrix. This catalyst is prepared by impregnating excess IZM-2 / alumina support prepared according to Example 4 with an aqueous solution containing hexachloroplatinic acid. The concentration of hexachloroplatinic acid in the solution is 2.55 10-3 mol / l.

20 grams of support are used, the pore volume of which is filled with distilled water and the solid is allowed to mature for one hour at room temperature. The solid is then immersed in 80 ml of a hydrochloric acid HCl solution of concentration 3.52 10-1 mol / l in an Erlenmeyer flask then the whole is stirred on a stirring table (100 revolutions / min ) at room temperature for one hour. The hydrochloric acid solution is then withdrawn then the solid is immersed in 80 ml of the hexachloroplatinic acid solution described above, then the whole is stirred on a stirring table (100 revolutions / min) at room temperature for 24 hours. The impregnation solution is then drawn off and the solid is rinsed with 160 ml of distilled water. The solid is then left to dry in a ventilated oven overnight at 110 ° C. and a calcination step is finally carried out under a flow of dry air (2 normal liters per hour and per gram of solid) in a tube furnace under the conditions following:

- temperature rise to ambient to 500 ° C at 5 ° C / min,

- two hour hold at 500 ° C,

- descent to ambient.

The Pt content measured by FX on the calcined catalyst is 0.2% by weight relative to the total mass of the catalyst, its distribution coefficient measured by Castaing microprobe of 1.0. The catalyst obtained does not undergo a washing step with an ammonium nitrate solution. The sodium content in the catalyst measured by atomic absorption is 37 ppm by weight.

The textural properties of catalyst D were characterized by nitrogen porosimetry at 196 ° C on a Micromeritics ASAP 2010 device. Before nitrogen adsorption, the solid is degassed under vacuum at 90 ° C for one hour and then at 350 ° C for four hours. The total pore volume corresponds to the volume of nitrogen adsorbed at a relative pressure of 0.97. The specific surface area of the solid is calculated by the BET method and the median pore diameter calculated according to the BJH adsorption model corresponds to the diameter for which half the volume of nitrogen is adsorbed. Catalyst D has a specific surface area of 285 m ² / g, a total pore volume of 0.65 ml / g and a median diameter of 13 nm.

Example 8: Evaluation of the catalytic properties of catalysts C, B and D in accordance with the invention and A not in accordance with the invention, in isomerization of a paraffinic feed.

The catalysts were tested for isomerization of a paraffinic feed composed of n-hexadecane. The tests were carried out in a micro-unit implementing a fixed bed reactor and working in downdraft without recycling. The analysis of hydrocarbon effluents is carried out online by gas chromatography. Once loaded into the unit, the catalyst undergoes a first drying step under nitrogen under the following conditions:

- nitrogen flow: 2 normal liters per hour and per gram of catalyst,

- total pressure: 0.1 MPa,

- ambient temperature rise ramp to 150 ° C: 5 ° C / min,

- stop at 150 ° C for 30 minutes.

After drying, the nitrogen is replaced by hydrogen and a reduction step under a flow of pure hydrogen is then carried out under the following conditions:

- hydrogen flow rate: 5 normal liters per hour and per gram of catalyst,

- total pressure: 1.1 MPa,

- temperature rise ramp from 150 to 450 ° C: 5 ° C / min,

- level at 450 ° C for 1 hour.

After the reduction step, the temperature has dropped to 230 ° C., and the catalyst is contacted with n-hexadecane under the following conditions:

- hourly space velocity of 2 grams of n-hexadecane per hour and per gram of catalyst,

- partial pressure of hydrogen of 1.0 MPa,

- total pressure of 1.1 MPa. The conversion is changed by varying the temperature; and at each temperature level two analyzes of the effluent are carried out, which makes it possible to calculate the catalytic performance and to verify the stability of the catalytic performance for said temperature level. Typically, the temperature is varied between 230 and 350 ° C in a temperature step of 5 ° C. The effluent analysis is carried out entirely through an on-line GC system. The temperature necessary to achieve 50% conversion acts as a descriptor of the activity of the catalyst while the maximum yield obtained in hexadecane isomers acts as a descriptor of the isomerizing properties of the catalyst. Table 2 represents the catalytic performances of catalysts A, B, C and D in hydroconversion of n-hexadecane.

Catalysts A and B are distinguished only by their residual sodium content, while the deposition protocol and the amount of platinum deposited are the same. It can be seen that the decrease in the sodium content from 255 ppm to 42 ppm in the catalyst makes it possible to significantly improve its catalytic activity: the temperature necessary to reach 50% conversion is 11 ° C lower for catalyst B than for catalyst B. catalyst A. Remarkably, the isomerization selectivity of the two catalysts is the same since the maximum isomer yield is identical (85%). Decreasing the sodium content increases the catalytic activity while retaining the isomerizing properties of the catalyst.

Catalysts C and D are distinguished only by their residual sodium content, while the deposition protocol and the amount of platinum deposited are the same. It is noted that the reduction in the sodium content from 180 ppm to 37 ppm in the catalyst allows significantly improve its catalytic activity: the temperature necessary to achieve 50% conversion is 8 ° C lower for catalyst B than for catalyst A. Remarkably, the isomerization selectivity of the two catalysts is the same since the yield maximum in isomers is the same (83%). The reduction in the sodium content makes it possible to increase the catalytic activity while retaining the isomerizing properties of the catalyst.

The Pt deposition methods and the Pt contents deposited on catalysts A and B and on catalysts C and D are different. It can be seen that regardless of the method of deposition of Pt and its content on the catalyst, the decrease in the sodium content on the catalyst has the same effect: increase in catalytic activity and retention of isomerizing properties.

Claims

1. Process for isomerization of paraffinic feeds operating at a temperature between 200 ° C and 500 ° C, at a total pressure between 0.45 MPa and 7 MPa, at a partial pressure of hydrogen between 0.3 and 5.5 MPa, at an hourly space velocity of between 0.1 and 10 kilogram of feed introduced per kilogram of catalyst and per hour and using a catalyst comprising at least one metal from group VIII of the Periodic Table of the Elements, at minus one matrix and at least one IZM-2 zeolite, said catalyst being characterized in that the total weight content of alkaline and / or alkaline earth elements is less than 200 ppm by weight relative to the total mass of said catalyst, and greater than 20 ppm by weight.

2. The isomerization process according to claim 1 wherein said paraffinic filler is produced from renewable resources chosen from vegetable oils, algal or algal oils, fish oils and fats of vegetable or animal origin, or mixtures of such fillers.

3. Method according to one of claims 1 or 2 wherein said paraffinic feed is produced by hydrotreating said renewable resources.

4. The method of claim 1 wherein said paraffinic feed is a paraffinic feed produced by a process involving a step of upgrading by the Fischer-Tropsch route.

5. Method according to one of claims 1 to 4 wherein said catalyst has a total weight content of alkali and / or alkaline earth elements of less than 150 ppm by weight relative to the total mass of said catalyst.

6. The method of claim 5 wherein said catalyst has a total weight content of alkali and / or alkaline earth elements less than 100 ppm by weight relative to the total mass of said catalyst.

7. The method of claim 6 wherein said catalyst has a total weight content of alkali and / or alkaline earth elements less than 90 ppm by weight relative to the total mass of said catalyst.

8. The method of claim 7 wherein said catalyst has a total weight content of alkali and / or alkaline earth elements less than 80 ppm by weight relative to the total mass of said catalyst.

9. The method of claim 7 wherein said catalyst has a total weight content of alkali and / or alkaline earth elements of less than 70 ppm by weight relative to the total mass of said catalyst.

10. Method according to one of claims 1 to 9 wherein the alkaline and / or alkaline earth elements are chosen from lithium, sodium, potassium, berylium, magnesium, barium, and calcium and preferably sodium. .

11. A method according to one of claims 1 to 10 wherein the group VIII element is platinum.

12. Method according to one of claims 1 to 11 wherein said matrix is advantageously chosen from the group formed by alumina, silica, silica-alumina, clays, titanium oxide, boron oxide. and zirconia, taken alone or as a mixture.