FR2735492A1 - PROCESS FOR THE CATALYTIC TRANSFORMATION OF HYDROCARBONS INTO AROMATIC COMPOUNDS WITH A CATALYST CONTAINING LANTHANIDES AND SILICON - Google Patents

Abstract

The electronic computer has a printed circuit board(12) carrying several electronic components (13) carried on support plates (11). A connector (14) at one edge of the computer allows connection to the external devices. The circuit board is enclosed (15) in a synthetic material applied after the components have been assembled. The synthetic material is chosen to have good thermal properties so it cools the electronic components and also to have good mechanical properties, so it provides mechanical protection for the circuit. The enclosure is sealed to isolate the components from the environment. Cooling is aided by forming recesses (16) in the enclosing layer immediately above components, the reduced thickness of material aiding heat removal.

Description

PROCESS FOR CATALYTIC TRANSFORMATION
OF HYDROCARBONS IN AROMATIC COMPOUNDS, WITH A
CATALYST CONTAINING LANTHANIDES AND SILICON.

 The present invention relates to a process for converting hydrocarbons into aromatic compounds using a solid catalyst which contains a matrix comprising at least one transition alumina selected from the group consisting of transition alumina y and transition alumina, at least a noble metal, at least one promoter metal, at least one halogen, silicon and at least one element selected from the group of lanthanides.

 Catalysts containing platinum and another metal deposited on a chlorine alumina support have long been known and widely used in the refining industry.

 These catalysts are bifunctional because they associate the acid function of chlorinated alumina with the dehydrogenating function of platinum. They have been the subject of many improvements. Many works have in particular sweat the dehydrogenating function of these catalysts and more precisely on the nature and manner of introduction of the metal added to platinum. This second metal has the main effect of promoting the dehydrogenating activity of platinum. In some cases, this second metal or promoter also has the effect of limiting the dispersion loss of the platinum atoms on the surface of the support.

This loss of dispersion is partly responsible for the deactivation of the catalyst.

 Among all the promoter metals studied, two metals play a predominant role: rhenium and tin. Indeed, these two metals are likely to provide the best platinum promotion effects.

 Thus, the use of rhenium has made it possible, in particular, to increase the stability of the catalyst with respect to its deactivation by coke deposition. This type of catalyst is used most often in fixed bed units. And thanks to this gain in stability, the duration of the reaction cydes between two regenerations, could be increased.

 Tin, meanwhile, has improved the performance of these catalysts when used at low pressure. This improvement, combined with their lower cracking activity, made it possible to obtain improved reformate yields, especially in continuous regeneration processes operating at low operating pressure.

 Despite the many improvements already made, it remains interesting to look for new catalysts giving even better yields while increasing their life.

 Conventionally, these catalysts are used either in fixed bed processes or in moving bed processes.

 In moving bed processes, the catalysts undergo a large number of regenerations. These treatments which consist, among other things, in shining the coke deposited on the catalyst, take place at high temperature and in the presence of water vapor.

Unfortunately, these conditions are favorable for the degradation of the catalyst. It is therefore important to seek to increase the resistance of the catalysts under these conditions.

 In addition, these catalysts are in the form of extrudates or beads of a sufficient size so as to allow a relatively easy passage to the reactants and gaseous products. The wear of these catalysts, particularly by friction in the moving bed units, causes the formation of dust and finer grains. These finer grains disturb the gas flow and force to increase the input pressure reagents or in some cases to stop the operation of the unit. In addition, in mobile bed units, this progressive wear has the effect of disrupting the circulation of the catalyst and necessitating the frequent addition of fresh catalyst.

 It is therefore obvious that all the improvements enabling the catalyst to retain its properties are essential to increase the life of these catalysts. Of course these improvements should not affect the performance of the catalyst.

 In fixed bed processes, the number of regenerations is much lower; the problem of the stability of the catalysts is therefore less important. It is then sought to use a catalyst which has a maximum level of activity for hydrocarbon conversion but, in addition, which activates this transformation with the greatest possible selectivity. In particular, losses of hydrocarbons in the form of light products containing from 1 to 4 carbon atoms must be limited. The acid function is necessary for aromatic and octane-improving reactions.

Unfortunately, this function is also responsible for cracking reactions that lead to the formation of light products. Therefore, it is clear that the optimization of the quality of this acid function is important to gain further selectivity without, however, reducing the activity of the catalyst.

 The preparation of catalysts consisting of chlorinated alumina containing platinum and a second metal can be carried out in two ways. A first way is to introduce the metals before shaping. A second way is to deposit the noble metal of the platinum family, the promoter metal and the chlorine on the preformed matrix.

The preparation and shaping of the matrix can thus be the first step in the preparation of these catalysts. The matrices generally used are chosen from the refractory oxides of metals of groups II, III and IV of the periodic table of elements. Most often aluminum oxide of general formula A1203, nH2O is used. Its specific surface is between 150 and 400 m2 / g. This oxide, in which n is between 0 and 0.6, is conventionally obtained by controlled dehydration of hydroxides in which 1 n zon <3. These amorphous hydroxides are themselves prepared by precipitation in aqueous medium of aluminum salts with alkaline salts. Precipitation and ripening conditions determine several forms of hydroxides, the most common being boehmite (n = 1), gibbsite and bayerite (n = 3). Depending on the hydrothermal treatment conditions, these hydroxides give several transition oxides or aluminas. There are thus the forms p, y, zE, x, 0, 6, K and a which are essentially differentiated by the organization of their crystalline structure,
During heat treatments, these different forms are susceptible to change between them, according to a complex parentage that depends on the operating conditions of the treatment. The form, which has a surface area and almost zero acidity, is the most stable at high temperatures. For reforming catalysts, shape transition alumina is most often used because of the compromise between its acidity and thermal stability properties.

The research work carried out by the Applicant led her to discover that, surprisingly, catalysts containing:
a matrix consisting of at least one transition alumina chosen from the group
formed by the transition alumina t1 and the transition alumina y at a rate of 0 to 100%
the weight of transition alumina z1, the complement at 100% by weight of the matrix being
the transition alumina y,
and with respect to the weight of catalyst:
from 0.001 to 2% by weight of silicon,
from 0.001 to 10% of at least one element selected from the group of lanthanides.

from 0.1 to 15% of at least one halogen selected from the group consisting of fluorine,
chlorine, bromine and iodine,
from 0.01 to 2% of at least one noble metal of the platinum family,
from 0.005 to 10% of at least one promoter metal selected from the group consisting of
tin, germanium, indium, gallium, thallium, antimony, lead,
rhenium, manganese, chromium, molybdenum and tungsten, makes it possible to obtain catalytic performances in hydrocarbon conversion reactions to aromatic compounds, in particular reforming and aromatics production reactions, which are significantly improved compared to those of the catalysts of the prior art.

 The catalyst matrix preferably comprises at least one transition alumina, said transition alumina being of γ-form and the alumina weight composition ranging from 0 to 99% or rather up to 84%, preferably 3 to 70%. and more preferably from 5 to 50%, the complement at 100% by weight of the matrix being transition alumina y.

 In a preferred embodiment of the invention, the matrix consists of 0.1 to 84% by weight of transition alumina ra, the complement at 100% by weight being alumina.

 The transition alumina 10 is obtained by calcining bayerite in dry air, at atmospheric pressure, between 250 and 500 ° C and preferably between 300 and 450 ° C. The specific surface area which depends on the final calcination temperature is between 300 and 500 m 2 / g. The alumina comes from boehmite by calcination in air at a temperature of between 450 and 600 ° C. The specific surface area of the alumina obtained therein is between 100 and 300 m 2 / g.

 These two transition aluminas have close but distinct crystalline structures.

The X-ray diffraction technique makes it possible to differentiate them. Their structures are of the spinel type with defects, their networks deviating slightly from the cubic symmetry. This quadratic deformation is minimal for the form 10 and clearly marked for alumina r whose mesh parameters are as follows: a = b = 7.95 A and c = 7.79 A.

The process for preparing the catalyst used in the process according to the invention, said catalyst containing at least one transition alumina and metals, comprises:
a) preparation, possibly by mixing and then shaping a matrix in
transitional alumina, of transition alumina or of a mixture of alumina
transition y and preferably in the proportions mentioned above).

b) deposits on at least one transition alumina selected from the group consisting of
transition alumina y and transition alumina 10 of at least
relate to the total weight of the catalyst):
from 0.001 to 2% by weight of silicon,
from 0.001 to 10% of at least one element selected from the group of
lanthanides.

from 0.1 to 15% of at least one halogen selected from the group consisting of
fluorine, chlorine, bromine and iodine,
from 0.01 to 2% of at least one noble metal of the platinum family,
from 0.005 to 10% of at least one promoter metal selected from the group
consisting of tin, germanium, indium, gallium, thallium,
Antimony, lead, rhenium, manganese, chromium, molybdenum and
tungsten,
steps a) and b) can be performed in any order, but
preferably step a) is performed before step b) and the deposits of step b) can
in part only before step a) and may be carried out in
any order.

 Optionally, it is incius treatment at high temperature in the presence of water and optionally halogen.

When the catalyst is used in a fixed bed process, a preferred method of preparing the catalyst comprises incorporating at least one promoter metal selected from the group consisting of rhenium, manganese, chromium, molybdenum, tungsten ,
Indium and thallium.

When the catalyst is used in a moving bed process, a preferred method of preparing the catalyst comprises incorporating at least one promoter metal selected from the group consisting of tin, germanium, indium, gallium, thallium,
Antimony and lead.

 The shaping of an alumina or of the mixture of these two aluminas can be carried out by using the catalyst shaping techniques known to those skilled in the art, such as, for example: extrusion, drop coagulation, coating, spray drying or pelleting.

The silicon may be deposited via compounds such as, for example, alkyl tetraorthosilicates, silicon alkoxides, quaternary ammonium silicates, silanes, disilanes, silicones, siloxanes, silicon halides, halosilicates and silicon in the form of microspheres of colloidal silica. In the case where the silicon precursor is a fluorosilicate of a cation of formula M2 / XSiF6 M is a metal or non-metallic cation having the valence x and chosen from the following cations: NH4 +, alkyls ammonium, K +, Na +, Li + , Ba2 +, Mg2 +, Cd2 +, Cu +, Cu2 +
Ca2 +, Cs +, Fe2 +, Co2 +, Pb2 +, Mn2 +, Rb +, Ag +, Sr2 +, Zn2 +, Tl + and H +.

 The deposition of silicon on the matrix of the catalyst of the present invention is feasible according to all techniques known to those skilled in the art and can intervene at any time during the preparation of the catalyst. For example, silicon can also be introduced in the liquid or gaseous phase. In the case where the silicon is deposited after forming the alumina or possibly containing other metals, the methods used may be for example dry impregnation, impregnation with excess solution or ion exchange. . On an already shaped matrix, a preferred method of introducing this additional element is the impregnation in an aqueous medium using an excess of solution. In order to eliminate the impregnating solvent, this impregnation is followed by drying. and calcining in air at a temperature of, for example, 300 to 900 ° C.

 The group of lantanides or rare earths is made up of elements of the lanthanum family in the Mendeleef periodic grading and whose atomic numbers are between 57 and 71. The element or elements chosen from this group, for example lanthanum, cerium, neodymium or praseodymium, may be deposited via compounds such as, for example, the halides, nitrates, carbonates, acetates, sulphates or oxalates of said elements.

 The deposition of at least one element of the lanthanum family on the matrix of the catalyst used in the present invention can be carried out according to all the techniques known to those skilled in the art, and can be carried out at any time during the preparation of the catalyst. For example, in the case where this element of the group of lanthanides or rare earths is deposited after the shaping of the alumina or possibly containing other metals, the dry impregnation, the impregnation by excess of solution or by ion exchange. On an already shaped matrix, a preferred method of introducing this additional element is the impregnation in an aqueous medium using an excess of solution. In order to remove the impregnating solvent, this impregnation is followed by drying and calcination in air at a temperature of, for example, between 300 and 900 ° C.

 The deposits of silicon and at least one element selected from the group of lanthanides can be made independently of each other and, or on a transition alumina or on the unformatted matrix, said matrix comprising 0 99% by weight of transition alumina and the complement to 100% by weight of transition alumina y, or else on the preformed matrix, the latter method being preferred.

 In the context of this description, the term "matrix" therefore refers to alumina or the mixture of aluminas, and will be called "support" the set formed by the matrix and at least one other element.

 A preferred support thus consists of a matrix comprising 0 to 100% by weight of transition alumina rE, the complement at 100% by weight of the matrix being transition alumina y of 0.001 to 2.7%. weight of silicon relative to the support, and from 0.001 to 13.7% by weight relative to the support of at least one element selected from the group of lanthanides.

 Advantageously, the matrix consists of 0 to 99%, advantageously 0 to 84%, preferably 3 to 70%, and more preferably 5 to 50% by weight of transition alumina Tl, and the support contains 0.001 to 2.7. %, preferably 0.01 to 1.35% by weight of silicon, and from 0.001 to 13.7% of at least one member selected from the group of lanthanides, preferably 0.001 to 0.65% and more preferably 0, 0.1 to 0.65% when the catalyst is used in a fixed-bed process, preferably more than 0.5 to 13.7% more preferably more than 0.5 to 5.5% by weight or 0.7 to 5.5% when the catalyst is used in a moving bed process.

 Deposition of at least one noble metal of the platinum family can occur at any time during the preparation of the catalyst. At least one noble metal of the platinum family and at least one promoter metal according to the invention is used for the impregnation, ie a common solution of at least two of the metals which it is desired to introduce, either distinct solutions. When several solutions for the impregnation of metals are used, dryings and / or intermediate calcinations can be carried out. It is usually terminated by calcination, for example between 300 and 900 ° C., preferably in the presence of molecular oxygen, for example by conducting an air sweep.

 At least one noble metal of the platinum family may be deposited on the matrix by impregnation of said matrix with a solution, aqueous or not, containing a salt or a noble metal compound. Platinum is generally introduced into the matrix in the form of chloroplatinic acid, but for any noble metal may also be used ammonia compounds or compounds such as for example ammonium chloroplatinate, platinum dicarbonyl dichioride, hexahydroxyplatinic acid , palladium chloride, palladium nitrate.

The use in the present invention of at least one noble metal of the platinum family can be exemplified by the use of ammonia compounds. In the case of platinum, mention may be made, for example, of hexamines IV platinum salts of formula Pt (NH 3) eX 4, platinum IV halopentamine salts of formula (RX (NHi 5) X 3, platinum tetrahalogenodiamine salts of formula PtX 4 (NH 3 ) 2, platinum complexes with halogen-polyketones and halogenated compounds of formula H (Pt (aca) 2) o.
X is a halogen selected from the group consisting of chlorine, fluorine, bromine and iodine, and preferably chlorine.The aca group represents the radical of formula C5H702 derived from acetylacetone. The introduction of the noble metal of the platinum family is preferably carried out by impregnation with an aqueous or organic solution of one of the organometallic compounds mentioned above. Among the organic solvents that can be used, mention may be made of paraffinic, naphthenic or aromatic hydrocarbons, and halogenated organic compounds having, for example, from 1 to 12 carbon atoms per molecule. For example, n-heptane, methylcyclohexane, toluene and chloroform may be mentioned. Solvent mixtures can also be used.

 After introduction of at least one noble metal of the platinum family, the product obtained is optionally dried and then calcined preferably at a temperature between 400 and 700 ° C.

 The promoter metal (s) selected from the group consisting of tin, germanium, indium, gallium, thallium, antimony, lead, rhenium, manganese, chromium, molybdenum and tungsten may be introduced at any time during the preparation of the catalyst. Deposition may be effected for example by means of compounds such as halides, nitrates, acetates, tartrates, citrates, carbonates and oxalates of these metals. Any other salt or oxide of these metals soluble in water, acids, or other suitable solvent is also suitable for introducing at least one of these promoter metals. Mention may be made, for example, of menates, chromates, molybdates and tungstates. The introduction of at least one promoter metal may be carried out before or after the deposition of at least one noble metal of the platinum family. when we chose, of course, to deposit these two types of metals separately. In this case, it is possible to introduce, for example, at least one promoter metal by mixing an aqueous solution of one of its precursor compounds with the alumina before shaping. In this case, before proceeding with the introduction of at least one noble metal, calcination is carried out under air at a temperature between 400 and 900 C.

 The introduction of the promoter metal or metals can also be carried out using a solution of an organometallic compound of said metals in an organic solvent.

In this case, after depositing at least one noble metal of the platinum family and calcining the solid, the introduction of at least one second metal, optionally preceded by a reduction with hydrogen at high temperature, is carried out, for example between 300 and 500 ° C. These organometallic compounds are chosen from the group consisting of complexes of said promoter metal, in particular polyketone complexes and hydrocarbylmetals such as alkyls, cycioalkyls, aryls, alkylaryls and arylalkyls. It is also possible to use organohalogen compounds. In particular, tetrabutyltin may be mentioned in the case where the second metal is tin, tetraethylplomb in the case where this metal is lead and triphenylindium in the case where the metal is indium The impregnating solvent is selected from the group consisting of paraffinic, naphthenic or aromatic hydrocarbons containing from 6 to 12 atoms of carbon per molecule and halogenated organic compounds containing from 1 to 12 carbon atoms per molecule. For example, n-heptane, methylcyclohexane and chloroform may be mentioned. It is also possible to use mixtures of the solvents defined above.

 The halogen and preferably the chlorine can be introduced from at least one of the halides of the platinum family of metals or at least one of the halides of the second metal, in the case where these metals are introduced from halides. A complementary method may consist in impregnating the matrix or the support with an aqueous solution containing an acid or a halogenated salt. For example, chlorine can be deposited using a hydrochloric acid solution. Another method may consist of calcination at a temperature generally of between 400 and 900 ° C., in the presence of an organic compound containing halogen, such as, for example, Cl 14, CH 2 Cl 2, CH 3 Cl, etc.

 The metals, silicon and at least one halogen can be deposited on at least one of the transition aluminas by impregnation. We use either a single solution containing all these elements, or separate solutions for each element. When several solutions are used, dryings and / or intermediate calcinations can be carried out.

 The mixture of the two aluminas may be carried out before or after deposition of a part of the silicon on at least one transition alumina. If mixing (before shaping) is performed after the deposition. said deposition is carried out at least partly (and better still) preferably on the transition alumina r. In the same way, the mixture of the two aluminas may be carried out before or after the deposition of at least a portion of at least one element selected from the group of lanthanides on at least one transition alumina. If the mixing is performed after the deposition, said deposition is carried out in part (and better still) preferably on the transition alumina 10.

 In the same way, the mixture of the two aluminas can be carried out before or after the deposition of the metals and at least one halogen. The mixture is advantageously carried out before depositing the metals and at least one halogen.

 Finally, the preparation of these catalysts comprising halogenated alumina containing at least one noble metal of the platinum family and at least one promoter metal, usually ends with calcination for example between about 300 and 1000 ° C.

 The order in which the silicon is deposited, at least one element selected from the group of lanthanides, at least one noble metal of the platinum family, at least one promoter metal and at least one halogen, before or after the shaping , does not matter.

But preferably, a preparation process, which we detail below, comprises for example the following successive steps:
a) shaping of the catalyst matrix, comprising at least one alumina of
transition chosen in the group formed by alumina and alumina 10.

b) introduction (deposition) on this shaped matrix of silicon and at least one
element selected from the group consisting of lanthanides,
c) depositing at least one promoter metal chosen from tin, germanium, indium,
gallium, thallium, antimony, lead, rhenium, manganese, chromium,
molybdenum and tungsten,
d) depositing at least one element selected from the group consisting of fluorine, chlorine,
bromine and iodine,
e) depositing at least one noble metal of the platinum family,
After forming the matrix and depositing all the constituents, it is possible to carry out a final heat treatment between 300 and 1000 ° C., which may comprise only one step at a temperature of 400 to 900 ° C. preferably, and in an atmosphere containing oxygen, and preferably in the presence of free oxygen or air.This treatment generally corresponds to the secahecalcination following the deposition of the last component.

 After forming the matrix and depositing all the constituents, a heat treatment is preferably carried out which can be complementary to the preceding treatment which can be carried out at a temperature of 300 to 1000 ° C., preferably 400 to 700 ° C. in a gaseous atmosphere containing water vapor and optionally a halogen such as chlorine.

 This treatment can be carried out in bed traversed by a stream of gas or in a static atmosphere. The gaseous atmosphere used is for example based on air, oxygen, argon or nitrogen, or their mixtures. This atmosphere contains water and possibly at least one halogen. The molar content of water is between 0.05 and 100%, preferably between 1 and 50%. The molar content of halogen is between 0 and 20%, advantageously between 0 and 10% and preferably between 0 and 2%. The duration of this treatment is variable depending on the conditions of temperature, partial pressure of water and amount of solid. This value is advantageously between one minute and 30 hours, preferably from 1 to 10 hours.

 In some cases, the role of this high temperature treatment in the presence of water is important. As shown in the examples described hereinafter, the presence of silicon and at least one element selected from the lanthanide group preserves the alumina matrix (s) from its loss of specific surface area during the various regenerative treatments.

Unfortunately, at the same time, when at least one element selected from the group of lanthanides is present in large excess relative to the silicon (that is, to read when the molar ratio of the element or elements selected from the group of lanthanides on the silicon is greater than or equal to 3), this presence causes the degradation of the catalytic performances. Unexpectedly, and in the presence of this large excess of element (s) chosen (s) in the group of lanthanides relative to silicon, a severe heat treatment in the presence of water applied to this type of catalyst has the effect of maintain the least loss of specific surface area while improving catalytic performance.

The catalyst used in the process of the present invention thus contains in weight, in addition to the matrix:
from 0.01 to 2.00% and preferably from 0.10 to 0.80% of at least one noble metal of the
platinum family,
from 0.005 to 10.00% and preferably from 0.01 to 1.00% of at least one promoter metal
selected from the group consisting of tin, germanium, indium, gallium,
thallium, antimony, lead, rhenium, manganese, chromium, molybdenum and
tungsten. If the catalyst is used in a moving bed process, the metal
promoter is preferably selected from the group consisting of tin,
germanium, indium, gallium, thallium, antimony and lead, and preferably
still, at least one promoter metal is tin. If the catalyst is used in a
fixed-bed method, the promoter metal is preferably selected from the group
consisting of rhenium, manganese, chromium, molybdenum, tungsten,
Indium and thallium, and more preferably at least one promoter metal is the
In the case where the catalyst contains a single promoter metal, its content is
between 0.005 and 0.90% and preferably between 0.01 and 0.80%,
from 0.10 to 15.0% and preferably from 0.20 to 10.0% of at least one halogen chosen from
group consisting of fluorine, chlorine, bromine and iodine,
from 0.001 to 2.0% and preferably from 0.01 to 1.0% of silicon,
and from 0.001 to 10.0% of at least one additional element selected from the group of
lanthanides, preferably between 0.001 and 0.5% and more preferably between 0.01 and
0.50% when the catalyst is used in a fixed bed process, preferably between
more than 0.5% and 10% or 4% and more preferably between 0.501 and 10% or 4%, and
best between 0.7% and 4% when the catalyst is used in a moving bed process.

 At the end of the preparation according to the invention, the calcined catalyst used in the process according to the invention can advantageously undergo an activation treatment under hydrogen at high temperature, for example between 300 and 550 ° C. The hydrogen treatment consists for example in a slow rise in temperature under a stream of hydrogen up to the maximum reduction temperature, generally between 300 and 5500C and preferably between 350 and 450ex, followed by maintenance at this temperature for a duration generally between 1 and 6 hours.

 The invention relates to a process using the catalyst described above, in hydrocarbon conversion reactions to aromatic compounds and more particularly in the reforming reactions of gasolines and production of aromatics. The reforming processes make it possible to increase the octane number of the gasoline fractions derived from the distillation of crude oil and / or other refining processes. The aromatics production processes provide the bases (benzene, toluene and xylenes) that can be used in petrochemicals. These processes are of additional interest in contributing to the production of large quantities of hydrogen essential for refinery hydrotreatment processes. These two processes are distinguished by the choice of operating conditions and the composition of the feedstock.

The typical feedstock treated by these processes contains paraffinic, naphthenic and aromatic hydrocarbons containing 5 to 12 carbon atoms per molecule. This load is defined, among other things, by its density and its weight composition. This filler is brought into contact with the catalyst of the present invention at a temperature between 400 and 700 C. The mass flow of treated filler per unit mass of catalyst may vary from 0.1 to 10 kg / kg / h. The operating pressure can be set between atmospheric pressure and 4 MPa, preferably 0.1 to 0.9 MPa, in a moving bed process and 1 to 2
MPa in a fixed-bed process.A portion of the hydrogen produced is advantageously recycled according to a molar recycling ratio of between 0.1 and 8.0. This rate is the molar ratio of recycled hydrogen flow rate to the feed rate.

 The following examples specify the invention without limiting its scope.

Example 1: Formatting matrices
The matrix A is prepared by extrusion of an alumina powder whose specific surface area is 220 m 2 / g. The matrix B is prepared by mechanical mixing of powders of the same alumina and alumina with a specific surface area of 320 m 2 / g and which has been prepared by calcination of bayerite. The proportion of alumina n is 40% by weight. This mixture is then shaped by extrusion. The two extruded matrices A and B are calcined under a stream of dry air at 520 ° C. for 3 hours.

Example 2: Silicon Deposition
After cooling, sample B is brought into contact with an ethanolic solution of tetraethyl orthosilicate Si (OC 2 H 5) 4. The concentration of this solution is 2.5 g of silicon per liter. This contact is carried out at room temperature for 2 hours with stirring. The solvent is then evaporated under reduced pressure. The impregnated extrudates are then dried at 1200 ° C. for 15 hours and calcined at 5 ° C. under a stream of dry air for 2 hours. The sample thus obtained is named C.

Example 3: lanthanum deposit
Part of the sample C is contacted with an aqueous solution of lanthanum nitrate La (NO 3) 96H 2 O. The concentration of this solution is 42.0 g of lanthanum per liter. This contact is carried out at room temperature for 2 hours. The support thus impregnated is then dried at 1200 ° C. for 15 hours and calcined at 5 ° C. under a stream of dry air for 2 hours. This sample is named E.

Another portion of Sample C is impregnated in the same manner but using a solution containing 21.0 grams of lanthanum per liter. The calcined sample is named
H.

Example 4 Platinum, Promoter Metal and Chlorine Deposition
The platinum, rhenium and chlorine deposition is carried out on part of the samples A, E and H. The platinum is deposited during a first impregnation of the support with an aqueous solution containing per liter:
8.20 g of chlorine in the form of HCI,
1.00 g platinum in the form of H 2 PtCl 6.

The solution is left in contact with the support for 2 hours. After wringing and drying for 4 hours at 1200 ° C., the impregnated support is calcined at 530 ° C. for 3 hours under a stream of dry air and the rhenium is then deposited by a second impregnation with an aqueous solution containing per liter:
4.20 g of chlorine in the form of HCI,
1.50 g of rhenium in the form of ReCl3.

After drying, the impregnated support is calcined at 530 ° C. for 2 hours under a stream of dry air After the deposition of the metals and chlorine, the samples are respectively named D, F and I.

The deposition of platinum, tin and chlorine is carried out on part of the support samples A, E and H. The protocol used consists of impregnating the support with a chlorinated aqueous solution containing per liter:
0.81 g of platinum in the form of H 2 PtCl 6,
0.96 g of tin as SnC12.

The solution is left in contact with the support for 2 hours. After drying and drying for 4 hours at 1200 ° C., the impregnated support is calcined at 530 ° C. for 3 hours under a stream of dry air After the metals and chlorine have been deposited, the samples are respectively designated J, K and L
Example S: heat treatment in the presence of water and chlorine
Sample F is treated at 510 ° C. for 2 hours under a current of 2000 dm3 / h of air per 1 kg of solid. This air contains water and chlorine injected into a preheating zone located upstream of the solid bed. The molar concentrations of water and chlorine are respectively 1% and 0.05%. The sample thus treated is called G.

 Sample K is treated at 500 ° C for 2 h under a current of 2000 dm3 / h of air per 1 kg of solid This air contains water and chlorine injected into a preheating zone upstream of The molar concentrations of water and chlorine are equal to 1.5% and 0.02%, respectively.

Finally, the characteristics of the catalyst samples containing the rhenium promoter metal are as follows:

<tb><SEP> proportion <SEP> content <SEP> in <SEP> content <SEP> in <SEP> content <SEP> in <SEP> content <SEP> in <SEP> content <SEP> in
<tb> sample <SEP> alumina <SEP> T '<SEP> platinum <SEP> rhenium <SEP> chlorine <SEP> silicon <SEP> lanthanum
<tb><SEP>%<SEP> weight) <SEP> (% <SEP> weight) <SEP> (% <SEP> weight) <SEP> (% <SEP> weight) <SEP> (% <SEP> weight) <SEP> (% <SEP> weight)
<tb> D <SEP> 0 <SEP> 0.23 <SEP> 0.25 <SEP> 1.12 <SEP> 0 <SEP> 0
<tb> G <SEP> 40 <SEP> 0.23 <SEP> 0.24 <SEP> 1, <SEP> 8 <SEP> 0.028 <SEP> 0.47
<tb><SEP> 40 <SEP> 0.22 <SEP> 0.24 <SEP> 1.09 <SEP> 0.028 <SEP> 0.11
<Tb>
And the characteristics of the catalyst samples containing as the tin-promoting metal are as follows:

<tb><SEP> proportion <SEP> surface <SEP> content <SEP> in <SEP> content <SEP> in <SEP> content <SEP> in <SEP> content <SEP> in <SEP> content <SEP> in
<tb> sample <SEP> alumina # <SEP> specific <SEP> platinum <SEP> tin <SEP> chlorine <SEP> silicon <SEP> lanthanum
<tb><SEP> (% wt) <SEP> (m2 / g) <SEP> (% wt) <SEP> (wt%) <SEP> (wt%) <SEP> (wt%) <SEP> ( %weight)
<tb> J <SEP> 0 <SEP> 219 <SEP> 0.25 <SEP> 0.18 <SEP> 1.15 <SEP> 0 <SEP> 0
<tb> M <SEP> 12 <SEP> 229 <SEP> 0.24 <SEP> 0.16 <SEP> 1.13 <SEP> 0.11 <SEP> 1.70
<tb> L <SEP> 12 <SEP> - <SEP> 231 <SEP> 0.24 <SEP> 0.16 <SEP> 1.08 <SEP> 0.13 <SEP> 0.82
<Tb>
Example 6 Catalyst Performance
6.1 catalysts D, G and I
Catalyst samples D, G and I, the preparation of which has been described previously, have been tested in charge transformation, the characteristics of which are as follows:
density at 20 C 0.742 kg / dm3
research octane number - 41
paraffin content 52.2% weight
Naphthenes content 32.4% by weight
aromatic content 15.4% by weight
The following operating conditions were used:
temperature 490
total pressure 1.4 MPa
mass flow rate (in kg.h-1) per 3.0 h-1
kilogram of catalyst
The performances of the catalysts are reported in the table below, and are
expressed in the weight efficiencies and the research octane number of the
reformate.

<Tb>

<SEP> yield <SEP> yield <SEP> yield <SEP> yield <SEP> c4- <SEP>
<tb> aromatic <SEP> reformat <SEP> hydrogen <SEP> aromatic <SEP> Cl <SEP> catalyst
<tb><SEP> (% <SEP> weight) <SEP> (% <SEP> weight) <SEP> (% <SEP> weight) <SEP> (% <SEP> weight)
<tb> D <SEP> 84.4 <SEP> 3.0 <SEP> 58.4 <SEP> 12.6 <SEP> 0.22
<tb> (comparative)
<tb> G (according to <SEP> 86.0 <SEP> 3.2 <SEP> 58.9 <SEP> 10.8 <SEP> 0.18
<tb><SEP> the invention)
<tb><SEP> I (according to <SEP> 85.2 <SEP> 3.2 <SEP> 59.2 <SEP> 11.6 <SEP> 0.20
<tb><SEP> the invention)
<Tb>
Comparing the performances of the catalysts G and D on the one hand, and those of the catalysts I and D, on the other hand, it is found that the catalysts G and I used in a process according to the invention have clearly improved performances. relative to the catalyst D of the prior art.

 In fact, the yields of C4 light cracking products obtained during the test of the two catalysts G and I according to the invention are very significantly lower than those observed on the comparative catalyst D.

 Thus, it can be seen that the ratio of yields of cracking products C on the yields of aromatic compounds, called C4- / aromatics in the table above, is lower for the two catalysts according to the invention G and I. The selectivity of the Catalysts vis-à-vis the desired aromatic products will be all the stronger as this ratio is low.

 The catalysts G and I according to the invention, which additionally contain, relative to the comparative catalyst D, alumina, silicon and lanthanum, have improved characteristics compared with the comparative catalyst D, in particular selectivities of cracking products. lower, and thus selectivities in improved aromatic products.

6.2 catalysts J, M and L
The J, M and L catalyst samples whose preparation has been described previously have been tested in a charge transformation whose characteristics are as follows:
density at 20 ° C 0.736 kg / dm3
research octane number -38
paraffin content 54.8% by weight
Naphthenes content 33.1% by weight
aromatic content 12.1% by weight
The following operating conditions were used:
temperature 500 "C
total pressure 0.40 MPa
charge rate 2.0 kg per kg of catalyst
duration 100 h
At the end of the operating time, the deactivated catalyst is regenerated by controlled combustion of the coke and adjustment of its chlorine content to about 1.10% by weight.

The specific surface of the support is measured after this regeneration. Then after high temperature activation of the catalyst with hydrogen, the charge is injected for a new period of operation. Thus, each catalyst was subjected to 5 operation-regeneration cycles. The specific surfaces corresponding to the beginning of the first and the last cycle and the performances obtained after 15 hours of operation in each of these two cycles are reported in the table below.

<Tb>

<SEP> surface <SEP> yield <SEP> index <SEP> yield <SEP> yield
<tb> sample <SEP> cycle <SEP> specific <SEP> reformat <SEP> octane <SEP> aromatic <SEP> C <SEP>
<tb><SEP> (m2l9) <SEP> (% <SEP> weight) <SEP> search <SEP> (% <SEP> weight) <SEP>% <SEP> weight)
<tb> J <SEP> 1 <SEP> 219 <SEP> 88.2 <SEP> 100.9 <SEP> 70.5 <SEP> 8.5
<tb><SEP> 5 <SEP> 194 <SEP> 89.4 <SEP> 98.6 <SEP> 67.8 <SEP> 7.5
<tb> M <SEP> 1 <SEP> 229 <SEP> 90.0 <SEP> 101.0 <SEP>, <SEP><SEP> 71.7 <SEP> 6.5
<tb><SEP> 5 <SEP> 224 <SEP> 90.8 <SEP> 100.1 <SEP> 71.1 <SEP> 5.7
<tb> L <SEP> 1 <SEP> 231 <SEP> 89.2 <SEP> 101.4 <SEP> 71.8 <SEP> 7.2
<tb><SEP> 5 <SEP> 222 <SEP> 90.2 <SEP> 100.3 <SEP> 70.8 <SEP> 6.4
<Tb>
Sample J is the comparative catalyst prepared according to the methods of the prior art. Samples M and L have been prepared according to the present invention, that is to say that they contain, inter alia, alumina, silicon and at least one element of the group of lanthanides and that they have possibly undergone a high temperature treatment in the presence of chlorine and water.

 Comparing the performance of samples M and L with those of sample J, we find that they have the best yields of aromatics and octane numbers of the reformate. We also note that these gains are made without reformat yields being affected.

 If we now consider the evolution during the 5 cycles, it appears that the fall of the specific surfaces of the samples M and L is much smaller than that of the comparative sample J. This lower drop is accompanied by a better maintenance of the aromatic yields and octane numbers.

 The process according to the invention thus makes it possible to substantially improve the results obtained by transforming hydrocarbons into aromatic compounds in terms of selectivity and stability during the reaction cycles.

Claims (35)

1- Process for the catalytic conversion of hydrocarbons into aromatic compounds, characterized in that the catalyst comprises:  a matrix constituting at least one selected transition alumina  in the group formed by the transition alumina n and the alumina of  transition y at from 0 to 100% weight of transition alumina Tl, the  complement to 100% by weight of the matrix being transition alumina y,  and relative to the total weight of catalyst ::  from 0.001 to 2% by weight of silicon,  from 0.001% to 10% by weight of at least one element selected from the group  lanthanides,  from 0.1 to 15% by weight of at least one halogen chosen from the group  consisting of fluorine, chlorine, bromine and iodine,  from 0.01 to 2% by weight of at least one noble metal of the platinum family,  from 0.005 to 10% by weight of at least one promoter metal chosen from  group consisting of tin, germanium, indium, gallium,  thallium, antimony, lead, rhenium, manganese, chromium,  molybdenum and tungsten. 2. Process according to claim 1, in which the catalyst matrix comprises 0 to 84% by weight of transition alumina T1. 3. Process according to one of claims 1 and 2 wherein the catalyst matrix comprises from 3 to 70% by weight of transition alumina R1. 4. Process according to one of claims 1 to 3 wherein the catalyst matrix comprises from 5 to 50% by weight of transition alumina T1. 5. Method according to one of claims 1 to 4 wherein the silicon content in the catalyst is 0.01 to 1% by weight. 6. Process according to one of claims 1 to 5 wherein the halogen content in the catalyst is from 0.2 to 10% by weight. 7- Method according to one of claims 1 to 6 wherein the noble metal content in the catalyst is 0.1 to 0.8% by weight. 8- Method according to one of claims 1 to 7 wherein at least one catalyst-promoting metal is selected from the group consisting of rhenium, manganese, chromium, molybdenum, tungsten, indium, thallium. 9- Method according to one of claims 1 to 8 wherein at least one promoter metal of the catalyst is rhenium. 10- Method according to one of claims 1 to 7 wherein at least one catalyst-promoting metal is selected from the group consisting of tin, germanium, indium, antimony, lead, thallium, gallium. 11. The process as claimed in claim 1, wherein at least one catalyst-promoting metal is tin. 12- Method according to one of claims 1 to 11 wherein the promoter metal content in the catalyst is 0.01 to 1% by weight. 13- Method according to one of claims 1 to 12 comprising 0.005 to 0.9% by weight of a single promoter metal in the catalyst. The process of claim 13 wherein the promoter metal content in the catalyst is from 0.01 to 0.8% by weight. 15. Process according to one of claims 8, 9 and 12 to 14 wherein the lanthanide content in the catalyst is from 0.001 to 0.5% by weight. 16- Method according to one of claims 8, 9 and 12 to 15 wherein the lanthanide content in the catalyst is 0.01 to 0.5% by weight. 17- Method according to one of claims 10 to 14 wherein the lanthanide content in the catalyst is more than 0.5% to 10% by weight. 18. Process according to one of claims 10 to 14 and 17 wherein the content of lanthanides in the catalyst is from 0.501 to 4% by weight. 19- Method according to one of claims 1 to 18 wherein the catalyst comprising at least one transition alumina and metals defined below is prepared according to the process comprising:  a) preparation, possibly by mixing and then shaping a  transition alumina matrix y, in transition alumina T1 or in  transition alumina mixture y and Ti,  (b) deposits on at least one transition alumina selected in  group consisting of transition alumina y and transition alumina  at least, based on the total weight of the catalyst,  0.001 to 2% by weight of silicon,  - 0.001 to 10% weight of at least one element selected from the group  lanthanides,  0.1 to 15% by weight of at least one halogen chosen from the group  consisting of fluorine, chlorine, bromine and iodine,  0.01 to 2% by weight of at least one noble metal of the family of  platinum,  0.005 to 10% by weight of a promoter metal selected from the group  consisting of tin, germanium, indium, gallium, thallium,  Antimony, lead, rhenium, manganese, chromium,  molybdenum and tungsten,  steps a) and b) can be performed in any order,  and the deposits of step b) can only be completed in part  before step a) and can be done in any order. 20- The method of claim 19 wherein to prepare the catalyst is formed the matrix comprising at least one transition alumina and then depositing the silicon and at least one lanthanide then depositing at least one promoter metal and then deposited at least one halogen then depositing at least one noble metal and then carrying out a heat treatment at a temperature of between 300 and 1000 C. 21 - Method according to one of claims 19 to 20, wherein the resulting product is subjected to a final heat treatment of a duration between 1 minute and 30 hours, at a temperature between 300 and 1000 "C under a gas atmosphere comprising water whose molar content is between 0.05 and 100%. 22. The process as claimed in claim 21, in which the catalyst comprises a molar ratio of lanthanides to silicon greater than or equal to 3. 23 - Method according to one of claims 19 to 22 wherein the molar content of water is between 1 and 50%. 24 - Method according to one of claims 19 to 23 wherein the treatment time is between 1 and 10 hours. 25 - Method according to one of claims 19 to 24 wherein the gaseous atmosphere comprises at least one halogen. 26 - Method according to one of claims 19 to 25 wherein the molar content of halogen is between 0 and 20%. 27 - Method according to one of claims 19 to 26 wherein the molar content of halogen is between 0 and 10%. 28 - Method according to one of claims 19 to 27 wherein the molar content of halogen is between 0 and 2%. 29 - Process according to one of claims 19 to 28 wherein the product obtained is subjected to a final heat treatment carried out at a temperature between 400 and 900 ° C. 30 - The method of claim 29 wherein the final heat treatment is carried out in the presence of free oxygen. 31 - Process according to one of claims I to 30 such that the treated feed contains paraffinic, naphthenic and aromatic hydrocarbons containing 5 to 12 carbon atoms per molecule and said feedstock is contacted with the catalyst at a temperature between 400 and 700 ° C and a pressure between atmospheric pressure and 4 MPa. 32 - Method according to one of claims 8 and 31 such that the pressure is between 1 and 2 MPa. 33 - Method according to one of claims 10 and 31 such that the pressure is between 0.1 and 0.9 MPa. 34 - Method according to one of claims 1 to 33 applied to reforming gasoline. 35 - Process according to one of claims 1 to 33 applied to the production of aromatic compounds from paraffinic and naphthenic hydrocarbons.