Method for preparing catalyst containing nickel active phase and nickel-copper alloy

Abstract

The present invention relates to a process for preparing a catalyst comprising nickel and copper and a porous alumina support, the process comprising the steps of: a) contacting an alumina support with a solution comprising a nickel precursor and a first organic compound having at least one carboxylic acid function; b) drying at a temperature of less than 250 DEG C and then calcining at a temperature of 250 DEG C to 550 DEG C; c) contacting the calcined catalyst precursor obtained at the end of step b) with a solution containing a nickel precursor, a copper precursor and a second organic compound having at least one carboxylic acid functional group; d) drying at a temperature of less than 250 DEG C.

Description

Technical Field

[0001] The present invention relates to a supported metal catalyst based on nickel and copper, intended in particular for the hydrogenation of unsaturated hydrocarbons and more particularly for the selective hydrogenation of polyunsaturated compounds or for the hydrogenation of aromatic compounds. Prior art

[0002] Catalysts for the selective hydrogenation of polyunsaturated compounds or for the hydrogenation of aromatic compounds are usually based on metals from Group VIII of the Periodic Table of Elements, such as nickel. The metal is deposited on a support in the form of nano-metal particles, which may be a refractory oxide. The content of Group VIII metal, the optional presence of a second metal element, the size of the metal particles and the distribution of the active phase in the support, as well as the nature and pore distribution of the support are parameters that may have an influence on the performance of the catalyst.

[0003] The rate of the hydrogenation reaction is determined by multiple criteria, such as the diffusion of reactants to the catalyst surface (external diffusion limitation), the diffusion of reactants to the active sites in the pores of the support (internal diffusion limitation), and the intrinsic properties of the active phase, such as the size of the metal particles and the distribution of the active phase within the support.

[0004] In order to obtain better catalytic performances, in particular better selectivity and / or activity, it is known in the prior art to use additives of the organic compound type to prepare metal catalysts for selective hydrogenation. For example, application FR2984761 discloses a method for preparing a selective hydrogenation catalyst comprising a support and an active phase comprising a metal of group VIII, said catalyst being prepared by a method comprising the steps of impregnating the support with a solution containing a precursor of a metal of group VIII and an organic additive, more particularly an organic compound exhibiting one to three carboxylic acid functional groups, drying the impregnated support and calcining the dried support to obtain the catalyst.

[0005] Furthermore, in order to improve the performance level of selective hydrogenation, it has often been proposed to promote nickel-based catalysts. For example, it is known from US5208405 to use a catalyst based on nickel and silver for C4-C 10 Selective hydrogenation of dienes. In addition, it is known to promote nickel, which is mainly present in the metals of group IB, in particular gold (FR2949077) or tin (FR2499078). Document FR 3011844 discloses a catalyst for carrying out a selective hydrogenation process, comprising a support and an active metal phase deposited on the support, the active metal phase comprising copper and at least one metal of nickel or cobalt, and the molar ratio of Cu:(Ni and / or Co) is greater than 1.

[0006] Finally, before adopting such a catalyst and using it in a hydrogenation process, a step of reduction treatment is carried out in the presence of a reducing gas, so as to obtain a catalyst comprising an active phase at least partly in metallic form. This treatment makes it possible to activate the catalyst and form metallic particles. This treatment can be carried out in situ or ex situ, that is to say after or before the catalyst is loaded into the hydrogenation reactor.

[0007] Document FR3099390A1 discloses a catalyst comprising nickel and copper and an alumina carrier, wherein the proportion of the nickel element relative to the total weight of the catalyst is 1 wt% to 50 wt%, and the proportion of the copper element relative to the total weight of the catalyst is 0.5 wt% to 15 wt%, and the catalyst is obtained via a preparation method comprising the following steps:

[0008] a) contacting an alumina support with at least one solution containing at least one nickel precursor;

[0009] b) contacting the alumina support with at least one solution containing at least one nickel precursor and at least one copper precursor;

[0010] c) contacting the alumina support with at least one solution containing at least one organic compound comprising at least one carboxylic acid functional group, or at least one alcohol functional group, or at least one ester functional group, or at least one amide functional group, or at least one amine functional group,

[0011] It should be understood that:

[0012] - steps a), b) and c) are performed separately in any order; or

[0013] - Steps a) and c) are performed simultaneously, and step b) is performed before or after the combination of steps a) and c);

[0014] - Steps b) and c) are performed simultaneously, and step a) is performed before or after the combination of steps b) and c);

[0015] d) carrying out at least one step of drying the catalyst precursor obtained at the end of steps a) to c) at a temperature of less than 250° C.;

[0016] e) a step of reducing the catalyst precursor obtained at the end of step d) by contacting said catalyst precursor with a reducing gas at a temperature greater than or equal to 150°C and less than 250°C.

[0017] Continuing their research in the field of catalysts for the selective hydrogenation of polyunsaturated compounds or for the hydrogenation of aromatic compounds, the Applicants have now determined that particularly active catalysts can be prepared by carrying out a specific preparation method in which, after depositing an active phase precursor based on nickel and in the presence of a specific organic additive, a metallic phase based on nickel and copper is added to the catalyst.

[0018] Without wishing to be bound by any theory, the Applicant has observed that, during the preparation of the catalyst, the step of bringing the catalyst into contact with a solution containing simultaneously a copper-based metal precursor, a nickel-based metal precursor and a specific organic additive, followed by a drying and reduction step at low temperature (greater than or equal to 150° C. and less than 200° C.) in the presence of a reducing gas, makes it possible to obtain a nickel-copper alloy (reduced form), which unexpectedly makes it possible to greatly improve the reducibility of the nickel active phase on the support, which is supplied in the step preceding the formation of the nickel-copper alloy (reduced form). The preparation method according to the invention thus makes it possible to carry out the step of reducing the metal elements in the presence of a reducing gas, at lower temperatures and shorter reaction times than those commonly used in the prior art. Advantageously, the use of operating conditions less harsh than those of the prior art makes it possible to carry out the reduction step directly in the reactor, wherein the purpose is to carry out the hydrogenation of aromatic compounds. However, the addition of nickel and copper after the addition of the active nickel phase inevitably leads to an increase in the nickel particles and therefore to a significant loss of activity. This is why the Applicant has determined that the addition of a specific organic additive, in a content much higher than that used during the impregnation of the active nickel phase, makes it possible to limit the growth of the nickel particles, or even to avoid it altogether.

[0019] Subject matter of the invention

[0020] A subject of the present invention is a method for preparing a catalyst comprising nickel and copper and a porous alumina support, the proportion of the nickel element relative to the total weight of the catalyst being between 1% and 50% by weight, the proportion of the copper element relative to the total weight of the catalyst being between 0.5% and 15% by weight, the size of the nickel particles in the catalyst measured in oxide form being less than 5 nm, the method comprising at least the following steps:

[0021] a) contacting the alumina support with at least one solution containing at least one first nickel precursor and at least one first organic compound comprising at least one carboxylic acid functional group to obtain a first catalyst precursor;

[0022] b) drying the first catalyst precursor obtained at the end of step a) at a temperature of less than 250° C. and then calcining the dried first catalyst precursor at a temperature ranging from 250° C. to 550° C. to obtain a calcined catalyst precursor;

[0023] c) contacting the calcined catalyst precursor obtained at the end of step b) with at least one solution containing at least one second nickel precursor, at least one copper precursor and at least one second organic compound comprising at least one carboxylic acid functional group, so as to obtain a second catalyst precursor;

[0024] d) drying the second catalyst precursor obtained at the end of step c) at a temperature of less than 250°C.

[0025] According to one or more embodiments, the molar ratio between the organic compound introduced in step a) and the nickel element also introduced in step a) is 0.01 to 5.0 mol / mol.

[0026] According to one or more embodiments, the molar ratio between the organic compound introduced in step c) and the nickel element also introduced in step c) is 0.02 to 5 mol / mol.

[0027] According to one or more embodiments, the molar ratio between the nickel introduced during steps a) and c) and the copper introduced during step c) is between 0.5 and 5 mol / mol.

[0028] According to one or more embodiments, the ratio between the molar ratio of the second organic compound to nickel introduced in step c) and the molar ratio of the first organic compound to nickel introduced in step a) is greater than 1.5.

[0029] According to one or more embodiments, steps a) and b) are performed at least twice before performing step c).

[0030] According to one or more embodiments, the first organic compound of step a) and the second organic compound of step c) are selected from oxalic acid, malonic acid, glycolic acid, lactic acid, tartronic acid, citric acid, tartaric acid, pyruvic acid and levulinic acid.

[0031] According to one or more embodiments, the first organic compound of step a) and the second organic compound of step c) are identical.

[0032] According to one or more embodiments, the copper precursor is selected from the group consisting of copper acetate, copper acetylacetonate, copper nitrate, copper sulfate, copper chloride, copper bromide, copper iodide, and copper fluoride.

[0033] According to one or more embodiments, the first nickel precursor and / or the second nickel precursor is nickel nitrate, nickel chloride, nickel acetate, or nickel hydroxycarbonate.

[0034] According to one or more embodiments, the process further comprises a step e) in which the catalyst obtained at the end of step d) is calcined at a temperature ranging from 250°C to 550°C.

[0035] According to one or more embodiments, the process further comprises a step f) in which the catalyst obtained at the end of step d), optionally at the end of step e), is reduced by contacting said catalyst with a reducing gas at a temperature greater than or equal to 150° C. and less than 250° C.

[0036] A further subject matter according to the invention relates to a catalyst obtainable by the preparation process according to the invention.

[0037] Another subject of the invention relates to a process for the selective hydrogenation of polyunsaturated compounds containing at least 2 carbon atoms per molecule contained in a hydrocarbon feedstock having a final boiling point lower than or equal to 300° C., in the presence of a catalyst according to the invention or obtained by the process for preparation according to the invention, at a temperature ranging from 0° C. to 300° C., at a pressure ranging from 0.1 to 10 MPa, when the process is carried out in the liquid phase, at a hydrogen / (polyunsaturated compound to be hydrogenated) molar ratio ranging from 0.1 to 10 and at a pressure ranging from 0.1 to 200 h / min. -1 or, when the process is carried out in the gas phase, at a hydrogen / (polyunsaturated compound to be hydrogenated) molar ratio of 0.5 to 1000 and a heating rate of 100 to 40000 h / s. -1 It is implemented at a time and space speed of.

[0038] Another subject of the invention relates to a process for hydrogenating at least one aromatic or polyaromatic compound present in a hydrocarbon feedstock having a final boiling point of less than or equal to 650° C., said process being carried out in the presence of a catalyst according to the invention or of a catalyst obtained by the process for preparation according to the invention, in the gaseous or liquid phase, at a temperature ranging from 30 to 350° C., a pressure ranging from 0.1 to 20 MPa, a hydrogen / (aromatic compound to be hydrogenated) molar ratio ranging from 0.1 to 10 and a reaction temperature ranging from 0.05 to 50 ° C. -1 It is implemented at a time and space speed of. DETAILED DESCRIPTION OF THE INVENTION

[0040] 1. Definition

[0041] Subsequently, the family of chemical elements is given according to the CAS classification (CRC Handbook of Chemistry and Physics, published by CRC Press, ed. DRLide, 81st edition, 2000-2001). For example, the VIII (or VIIIB) family according to the CAS classification corresponds to the metals of the 8th, 9th and 10th columns according to the new IUPAC classification.

[0042] In this specification, according to the convention of IUPAC, "micropores" are understood to refer to pores with a diameter less than 2 nm (i.e. 0.002 μm); "mesopores" are understood to refer to pores with a diameter greater than 2 nm (i.e. 0.002 μm) and less than 50 nm (i.e. 0.05 μm), and "macroporos" are understood to refer to pores with a diameter greater than 50 nm (i.e. 0.05 μm).

[0043] According to ASTM D4284-92, at a wetting angle of 140°, for example using Micromeritics TM The brand model is Autopore III TM The total pore volume was measured by mercury porosimetry using an apparatus.

[0044] The BET specific surface area is measured by a nitrogen physical adsorption method according to ASTM D3663-03 standard (the method described in the work “Adsorption by Powders & Porous Solids: Principles, Methodology and Applications” by Rouquerol F., Rouquerol J. and Singh K., Academic Press, 1999).

[0045] The median mesopore diameter is also defined as the diameter such that, among the combined pores that make up the mesopore volume, all pores with a size less than this diameter account for 50% of the total mesopore volume as determined by mercury porosimetry.

[0046] The term "size of nickel particles" is understood to refer to the diameter of nickel crystallites in the form of oxides. The diameter of nickel crystallites in the form of oxides is determined by X-ray diffraction, using the Scherrer relationship, by the width of the diffraction line located at an angle of 2θ = 43° (i.e., along the crystal direction

[200] ). This method is used in X-ray diffraction on polycrystalline samples or powders, which relates the full width at half height of the diffraction peak to the size of the particles, and is described in detail in the following references: Appl. Cryst. (1978), 11, 102-113, "Scherrer after sixty years: A survey and some new results in the determination of crystallite size", JI Langford and AJC Wilson.

[0047] The nickel and copper contents were measured by X-ray fluorescence.

[0048] In this specification, the term "comprising" is synonymous with "including" and "containing" (meaning the same), and is inclusive or open, and does not exclude other elements not specified. It should be understood that the term "comprising" includes the exclusive and closed term "consisting of...". In addition, in this specification, the term "substantially" corresponds to an approximate value of ±10% of a reference value (such as distance, speed, flow, compound content, temperature, pressure, etc.), preferably ±5%, and very preferably ±2%.

[0049] 2. Method for preparing catalyst

[0050] The steps of the preparation method are described in detail below.

[0051] Step a) contacting the support with a first nickel precursor and a first organic compound

[0052] According to the implementation of step a), the deposition of the first nickel precursor and the first organic compound comprising at least one carboxylic acid functional group on the support can be carried out by dry impregnation or overimpregnation, or by deposition-precipitation according to methods well known to those skilled in the art.

[0053] Preferably, step a) is performed by dry impregnation, which comprises contacting the catalyst support with a solution containing at least a first nickel precursor and at least one first organic compound containing carboxylic acid functional groups, the volume of the solution being 0.25 to 1.5 times the pore volume of the support to be impregnated.

[0054] Said step a) is preferably carried out by impregnating the support, for example by contacting said support with at least one solution, aqueous or organic (for example methanol or ethanol or phenol or acetone or toluene or dimethyl sulfoxide (DMSO)), or indeed consisting of a mixture of water and at least one organic solvent, containing at least partly in solution a first nickel precursor and at least a first organic compound comprising a carboxylic acid functional group, or by contacting said support with at least one colloidal solution of at least one nickel precursor and at least one first organic compound comprising a carboxylic acid functional group, said nickel precursor being in oxidized form (nanoparticles of nickel oxide, oxy(hydroxide) or hydroxide) or in reduced form (metallic nanoparticles of nickel in the reduced state). Preferably, the solution is aqueous. The pH of the solution can be varied by the optional addition of an acid or a base.

[0055] Preferably, the first nickel precursor is introduced in the form of an aqueous solution, for example in the form of a nitrate, carbonate, acetate, chloride or oxalate, in the form of a complex formed by a polyacid or an alcoholic acid and its salt, in the form of a complex formed with acetylacetonate, or in the form of any other inorganic derivative soluble in aqueous solution, and the nickel precursor is brought into contact with the support. Preferably, nickel nitrate, nickel chloride, nickel acetate or basic nickel carbonate are advantageously used as the first nickel precursor. Very preferably, the first nickel precursor is nickel nitrate.

[0056] The nickel concentration in the solution is adjusted according to the pore volume of the support still available so as to obtain, for the supported catalyst, a nickel content of 1% to 50% by weight, more preferably of 2% to 40% by weight, and even more preferably of 3% to 35% by weight, and even more preferably of 5% to 28% by weight of the element nickel relative to the total weight of the catalyst.

[0057] The first organic compound comprising at least one carboxylic acid functional group may be a saturated or unsaturated aliphatic organic compound or an aromatic organic compound. Preferably, the saturated or unsaturated aliphatic organic compound comprises 1 to 9 carbon atoms, preferably 2 to 7 carbon atoms. Preferably, the aromatic organic compound comprises 7 to 10 carbon atoms, preferably 7 to 9 carbon atoms.

[0058] The first saturated or unsaturated aliphatic organic compound or the aromatic organic compound comprising at least one carboxylic acid function may be chosen from monocarboxylic acids, dicarboxylic acids, tricarboxylic acids or tetracarboxylic acids.

[0059] Advantageously, the first organic compound comprising at least one carboxylic acid functional group is chosen from oxalic acid (oxalic acid), malonic acid (malonic acid), glutaric acid (glucoamic acid), hydroxyacetic acid (glycolic acid), 2-hydroxypropionic acid (lactic acid), 2-hydroxymalonic acid (succinic acid), 2-hydroxypropane-1,2,3-tricarboxylic acid (citric acid), 2,3-dihydroxysuccinic acid (tartaric acid), 2-oxopropionic acid (pyruvic acid) or 4-oxopentanoic acid (levulinic acid).

[0060] Advantageously, the molar ratio of the first organic compound introduced in step a) to the nickel element also introduced in step a) is 0.01 to 5.0 mol / mol, preferably 0.05 to 2.0 mol / mol, more preferably 0.1 to 1.5 mol / mol and still more preferably 0.3 to 1.2 mol / mol.

[0061] Step b) Drying and calcination

[0062] The first precursor of the catalyst obtained at the end of step a) is then dried at a temperature of less than 250° C., preferably from 15° C. to 180° C., more preferably from 30° C. to 160° C., still more preferably from 50° C. to 150° C., and in an even more preferred manner at 70° C. to 140° C., for a period of time generally ranging from 0.5 hours to 12 hours, and more preferably from 0.5 hours to 5 hours. Longer times are not excluded, but do not necessarily contribute to any improvement.

[0063] The drying step can be carried out by any technique known to those skilled in the art. It is advantageously carried out under an inert atmosphere or under an oxygen-containing atmosphere or under a mixture of an inert gas and oxygen. It is advantageously carried out under atmospheric pressure or under reduced pressure. Preferably, this step is carried out under atmospheric pressure and in the presence of air or nitrogen.

[0064] After drying, the first dried catalyst precursor is calcined at a temperature of 250° C. to 600° C., preferably 350° C. to 550° C., for a period of time of typically 0.5 to 24 hours, preferably 0.5 to 12 hours, and even more preferably 0.5 to 10 hours, preferably in an inert atmosphere or in an oxygen-containing atmosphere. Longer times are not excluded, but do not necessarily contribute to improvement.

[0065] Step c) contacting the calcined catalyst precursor with a copper precursor, a second nickel precursor and a second organic compound

[0066] The deposition of nickel, copper and the second organic compound comprising at least one carboxylic acid function onto the calcined catalyst precursor obtained at the end of step b) can be carried out by dry impregnation or overimpregnation, or also by deposition-precipitation, according to methods well known to those skilled in the art.

[0067] Preferably, said step c) is carried out by dry impregnation, which comprises contacting the calcined catalyst precursor with a solution comprising, preferably consisting of, at least one nickel precursor, at least one copper precursor and at least one second organic compound comprising at least one carboxylic acid functional group, the volume of which solution is from 0.25 to 1.5 times the pore volume of the support to be impregnated.

[0068] Said step c) is preferably carried out by simultaneously impregnating the calcined catalyst precursor obtained at the end of step b), comprising, for example, contacting said calcined catalyst precursor with at least one solution, said solution being aqueous or organic (for example methanol or ethanol or phenol or acetone or toluene or dimethyl sulfoxide (DMSO)), or consisting of a mixture of water and at least one organic solvent, said organic solvent comprising (preferably consisting of) at least one second nickel precursor at least partially in solution, at least one copper precursor at least partially in solution and one second organic compound comprising at least one carboxylic acid functional group, or contacting said calcined catalyst precursor with at least one colloidal solution comprising (preferably consisting of) at least one nickel precursor and one copper precursor in oxidized form (nanoparticles of nickel and copper oxides, oxy(hydroxides) or hydroxides) or in reduced form (metallic nanoparticles of nickel and copper in the reduced state) and at least one second organic compound comprising at least one carboxylic acid functional group. Preferably, the solution is aqueous. The pH of the solution can be varied by the optional addition of an acid or a base.

[0069] Preferably, the second nickel precursor and the copper precursor are introduced into an aqueous solution.

[0070] When the second nickel precursor is introduced into the aqueous solution, it is advantageous to use a second nickel precursor in the form of a nitrate, carbonate, acetate, chloride, hydroxide, basic carbonate, oxalate, sulfate or formates, in the form of a complex formed by a polyacid or an acid alcohol and its salt, in the form of a complex formed with acetylacetonate, in the form of a tetraamine or hexamine complex, or in the form of any other inorganic derivative soluble in aqueous solution, so that the nickel precursor is contacted with the catalyst precursor. Preferably, nickel nitrate, nickel hydroxide, nickel carbonate, nickel chloride or basic nickel carbonate are advantageously used as the second nickel precursor. Very preferably, the nickel precursor is nickel nitrate, nickel carbonate or nickel hydroxide.

[0071] When the copper precursor is introduced into the aqueous solution, it is advantageous to use the copper precursor in inorganic or organic form. In inorganic form, the copper precursor can be selected from copper acetate, copper acetylacetonate, copper nitrate, copper sulfate, copper chloride, copper bromide, copper iodide or copper fluoride. Very preferably, the copper precursor salt is copper nitrate.

[0072] The second nickel precursor is advantageously supplied in step c) in the desired concentration to obtain on the final catalyst (i.e. obtained at the end of drying / calcination step d) or reduction step e) (if the latter is carried out) a content of nickel element ranging from 0.5% to 10% by weight, preferably from 0.5% to 8% by weight, more preferably from 1% to 7% by weight, even more preferably from 1% to 5% by weight, relative to the total weight of the final catalyst.

[0073] The amount of copper precursor or precursors introduced into the solution according to step c) is chosen so that the total copper content relative to the total weight of the final catalyst (i.e. obtained at the end of drying / calcination step d) or reduction step e), if the latter is carried out, is between 0.5% and 15% by weight, preferably between 0.5% and 12% by weight, preferably between 0.75% and 10% by weight and even more preferably between 1% and 9% by weight of copper element.

[0074] The second organic compound comprising at least one carboxylic acid functional group may be a saturated or unsaturated aliphatic organic compound or an aromatic organic compound. Preferably, the saturated or unsaturated aliphatic organic compound comprises 1 to 9 carbon atoms, preferably 2 to 7 carbon atoms. Preferably, the aromatic organic compound comprises 7 to 10 carbon atoms, preferably 7 to 9 carbon atoms.

[0075] The second saturated or unsaturated aliphatic organic compound or the aromatic organic compound comprising at least one carboxylic acid function may be chosen from monocarboxylic acids, dicarboxylic acids, tricarboxylic acids or tetracarboxylic acids.

[0076] Advantageously, the second organic compound comprising at least one carboxylic acid functional group is chosen from oxalic acid (oxalic acid), malonic acid (malonic acid), glutaric acid (glucoamic acid), hydroxyacetic acid (glycolic acid), 2-hydroxypropionic acid (lactic acid), 2-hydroxymalonic acid (succinic acid), 2-hydroxypropane-1,2,3-tricarboxylic acid (citric acid), 2,3-dihydroxysuccinic acid (tartaric acid), 2-oxopropionic acid (pyruvic acid) or 4-oxopentanoic acid (levulinic acid).

[0077] Advantageously, the molar ratio of the second organic compound introduced in step c) to the nickel element also introduced in step c) is 0.02 to 5 mol / mol, preferably 0.1 to 3 mol / mol, more preferably 0.2 to 2 mol / mol and still more preferably 0.3 to 2 mol / mol.

[0078] Advantageously, the ratio between the molar ratio of the second organic compound and the nickel introduced in step c) and the molar ratio between the first organic compound and the nickel introduced in step a) is greater than or equal to 1.5, preferably between 2 and 5.

[0079] Advantageously, the second organic compound introduced in step c) is identical to the first organic compound introduced in step a).

[0080] Step d) Drying

[0081] The second precursor of the catalyst obtained at the end of step c) is then dried at a temperature of less than 250° C., preferably from 15° C. to 180° C., more preferably from 30° C. to 160° C., still more preferably from 50° C. to 150° C., and in an even more preferred manner at 70° C. to 140° C. for a period of time generally ranging from 0.5 hours to 12 hours, and more preferably from 0.5 hours to 5 hours. Longer times are not excluded, but do not necessarily contribute to an improvement.

[0082] The drying step can be carried out by any technique known to those skilled in the art. It is advantageously carried out under an inert atmosphere or under an oxygen-containing atmosphere or under a mixture of an inert gas and oxygen. It is advantageously carried out under atmospheric pressure or under reduced pressure. Preferably, this step is carried out under atmospheric pressure and in the presence of air or nitrogen.

[0083] Step e) Calcination (optional)

[0084] After drying, the catalyst obtained at the end of step d) is advantageously calcined at a temperature ranging from 250° C. to 600° C., preferably from 350° C. to 550° C., for a period generally ranging from 0.5 to 24 hours, preferably from 0.5 to 12 hours and even more preferably from 0.5 to 10 hours, preferably in an inert atmosphere or under an oxygen-containing atmosphere. Longer times are not excluded, but do not necessarily contribute to the improvement.

[0085] Step f) Reduction by reducing gas (optional)

[0086] In one embodiment according to the invention, before using the catalyst in a catalytic reactor and implementing the hydrogenation process, a reduction treatment step e) is carried out in the presence of a reducing gas, so as to obtain a catalyst comprising nickel at least partially in metallic form. This step is advantageously carried out in situ, that is to say, after the catalyst is loaded into the hydrogenation reactor. This treatment makes it possible to activate the catalyst and form metal particles, in particular nickel in the zero-valent state. The in situ implementation of the catalyst reduction treatment makes it possible to omit the additional step of passivation of the catalyst with oxygen-containing compounds or CO2, which is necessary when the catalyst is prepared by implementing an ex situ reduction treatment (that is, outside the reactor for the hydrogenation of aromatic or polyaromatic compounds). In fact, when the reduction treatment is carried out ex situ, a passivation step must be carried out to maintain the metal phase of the catalyst in the presence of air (during the operations of transport and loading of the catalyst into the hydrogenation reactor), followed by a new step of reducing the catalyst.

[0087] The reducing gas is preferably hydrogen. The hydrogen can be used pure or as a mixture (e.g., hydrogen / nitrogen, hydrogen / argon, or hydrogen / methane mixtures). In the case where hydrogen is used as a mixture, any ratio can be envisioned.

[0088] The reduction treatment is carried out at a temperature higher than or equal to 150° C. and lower than 250° C., preferably 160 to 230° C., and more preferably 170 to 220° C. The duration of the reduction treatment is 5 minutes to less than 5 hours, preferably 10 minutes to 4 hours, and even more preferably 10 minutes to 210 minutes.

[0089] The nickel-copper alloy present at least partially in reduced form makes it possible to reduce the nickel active phase using operating conditions less severe than those of the prior art, making it possible to carry out the reduction step directly in the reactor in which the hydrogenation of unsaturated compounds or aromatic compounds is desired.

[0090] Furthermore, the presence of copper in the catalyst makes it possible to maintain a good activity of the catalyst and a good service life of the catalyst when the catalyst is in contact with a hydrocarbon feedstock containing sulfur. In fact, the copper present in the catalyst more easily captures sulfur compounds contained in the feedstock than nickel, which limits the irreversible poisoning of the active sites. The temperature is usually raised slowly to the desired reduction temperature, for example set at 0.1 to 10°C / min, preferably 0.3 to 7°C / min.

[0091] The hydrogen flow rate expressed in liters / hour / gram of catalyst precursor is from 0.01 to 100 liters / hour / gram of catalyst precursor, preferably from 0.05 to 10 liters / hour / gram of catalyst precursor and still more preferably from 0.1 to 5 liters / hour / gram of catalyst precursor.

[0092] 3. Catalyst

[0093] The preparation method according to the present invention makes it possible to obtain a catalyst comprising nickel and copper and a porous alumina carrier, wherein the proportion of nickel element relative to the total weight of the catalyst is 1% to 50% by weight, and the proportion of copper element relative to the total weight of the catalyst is 0.5% to 15% by weight, and the size of the nickel particles measured in the form of oxide in the catalyst is less than 5 nm.

[0094] Preferably, at least a portion of the nickel and copper is in the form of a nickel-copper alloy, advantageously corresponding to the formula Ni x Cu y , wherein x is from 0.1 to 0.9, and y is from 0.1 to 0.9.

[0095] Preferably, the nickel content contained in the copper-nickel alloy is 0.5 to 15 wt %, preferably 1 to 12 wt %, and more preferably 1 to 10 wt % of nickel element relative to the total weight of the catalyst.

[0096] The size of the nickel particles in the catalyst measured in oxide form is less than 5 nm, more preferably less than 4 nm, and even more preferably less than or equal to 3 nm.

[0097] The nickel content in the catalyst is advantageously between 1% and 50% by weight, more preferably between 2% and 40% by weight, and even more preferably between 3% and 35% by weight, and even more preferably between 5% and 25% by weight relative to the total weight of the catalyst.

[0098] The copper content is from 0.5 to 15% by weight, preferably from 0.5 to 12% by weight, preferably from 0.75 to 10% by weight and even more preferably from 1 to 9% by weight of the copper element relative to the total weight of the catalyst.

[0099] The specific surface area of ​​the catalyst is usually 10m 2 / g to 350m 2 / g, preferably 25m 2 / g to 300m 2 / g, more preferably 40m 2 / g to 250m 2 / g.

[0100] The total pore volume of the catalyst is generally 0.1 ml / g to 1 ml / g, preferably 0.2 ml / g to 0.8 ml / g, and particularly preferably 0.3 ml / g to 0.7 ml / g.

[0101] The active phase of the catalyst preferably contains no metals from group VIB. In particular, it contains no molybdenum or tungsten.

[0102] The catalyst (and the support for the preparation of the catalyst) is in the form of particles, and its diameter is advantageously 0.5 to 10 mm. The particles can have any form known to those skilled in the art, such as beads (preferably 1 to 8 mm in diameter), extrudates, sheets or hollow cylinders. Preferably, the catalyst (and the support for the preparation of the catalyst) is in the form of extrudates, and its diameter is 0.5 to 10 mm, preferably 0.8 to 3.2 mm, and very preferably 1.0 to 2.5 mm and a length of 0.5 to 20 mm. The "diameter" of the extrudate is intended to refer to the diameter of the circle enclosed in the cross section of these extrudates. The catalyst can advantageously be presented in the form of cylindrical, multi-lobed, trilobed or quadrilobed extrudates. Preferably, its shape will be trilobed or quadrilobed. The shape of the blade will be able to be adjusted according to all known methods in the prior art.

[0103] 4. Carrier

[0104] The properties of the aluminium oxide mentioned in this section correspond to the properties of the aluminium oxide before being subjected to step a) of the preparation process according to the invention.

[0105] The support is aluminum oxide, that is to say it contains at least 95% by weight, preferably at least 98% by weight and particularly preferably at least 99% by weight of aluminum oxide relative to the weight of the support. The aluminum oxide generally has a crystalline structure of the delta-, gamma- or theta-alumina type, either alone or as a mixture.

[0106] The alumina support may contain impurities, such as oxides of metals from Group IIA, Group IIIB, Group IVB, Group IIB, Group IIIA and Group IVA according to the CAS classification, preferably silicon dioxide, titanium dioxide, zirconium dioxide, zinc oxide, magnesium oxide and calcium oxide, or alkali metals, preferably lithium, sodium or potassium, and / or alkaline earth metals, preferably magnesium, calcium, strontium or barium, or sulfur.

[0107] The specific surface area of ​​alumina is usually 10m 2 / g to 400m 2 / g, preferably 30m 2 / g to 350m 2 / g, more preferably 50m 2 / g to 300m 2 / g.

[0108] The pore volume of the aluminum oxide is generally from 0.1 ml / g to 1.2 ml / g, preferably from 0.3 ml / g to 0.9 ml / g and very preferably from 0.5 ml / g to 0.9 ml / g.

[0109] The median mesopore diameter is advantageously from 3 to 25 nm, preferably from 6 to 20 nm and particularly preferably from 8 to 18 nm.

[0110] 5. Selective hydrogenation method

[0111] Another subject of the present invention is a process for the selective hydrogenation of polyunsaturated compounds containing at least 2 carbon atoms per molecule, such as dienes and / or alkynes and / or alkenyl aromatic compounds (also called styrenes), contained in a hydrocarbon feedstock having a final boiling point lower than or equal to 300° C., in the presence of a catalyst obtained by the preparation process described above, at a temperature ranging from 0° C. to 300° C., at a pressure ranging from 0.1 to 10 MPa, when the process is carried out in the liquid phase, at a hydrogen / (polyunsaturated compound to be hydrogenated) molar ratio ranging from 0.1 to 10 and at a pressure ranging from 0.1 to 200 h. -1 or, when the process is carried out in the gas phase, at a hydrogen / (polyunsaturated compound to be hydrogenated) molar ratio of 0.5 to 1000 and a heating rate of 100 to 40000 h / s. -1 It is implemented at a time and space speed of.

[0112] Monounsaturated organic compounds, such as, for example, ethylene and propylene, are the basis for the preparation of polymers, plastics and other chemicals with added value. These compounds are obtained from natural gas, naphtha or gas oils which have been treated by steam cracking or catalytic cracking processes. These processes are carried out at high temperatures and, in addition to the desired monounsaturated compounds, also produce polyunsaturated organic compounds, such as acetylene, propadiene and methylacetylene (or propyne), 1,2-butadiene and 1,3-butadiene, vinylacetylene and ethylacetylene and other polyunsaturated compounds with boiling points corresponding to the C5+ fraction (hydrocarbon compounds with at least 5 carbon atoms), in particular dienes or styrenes or indenes. These polyunsaturated compounds are highly reactive and lead to side reactions in the polymerized units. It is therefore necessary to remove these polyunsaturated compounds before these fractions can be used economically.

[0113] Selective hydrogenation is the main process developed for the targeted removal of undesirable polyunsaturated compounds from these hydrocarbon feedstocks. It makes it possible to convert the polyunsaturated compounds into the corresponding olefins or aromatics, while avoiding their complete saturation and thus forming the corresponding alkanes or cycloalkanes. In the case of steam cracked gasoline used as feedstock, selective hydrogenation also makes it possible to selectively hydrogenate alkenyl aromatic compounds to produce aromatic compounds, while avoiding hydrogenation of aromatic rings.

[0114] The hydrocarbon feedstock treated in the selective hydrogenation process has a final boiling point of less than or equal to 300° C. and contains at least 2 carbon atoms per molecule and comprises at least one polyunsaturated compound. The term “polyunsaturated compound” is understood to mean a compound comprising at least one acetylenic function and / or at least one diene function and / or at least one alkenyl aromatic function.

[0115] More particularly, the feedstock is selected from the group consisting of a C2 steam cracking fraction, a C2-C3 steam cracking fraction, a C3 steam cracking fraction, a C4 steam cracking fraction, a C5 steam cracking fraction and steam cracking gasoline (also called pyrolysis gasoline or C5+ fraction).

[0116] The C2 steam cracking fraction advantageously used for implementing the selective hydrogenation process according to the invention has, for example, the following composition: 40 to 95% by weight of ethylene, and about 0.1 to 5% by weight of acetylene, the remainder being essentially ethane and methane. In some C2 steam cracking fractions, 0.1 to 1% by weight of C3 compounds may also be present.

[0117] The C3 steam cracking fraction advantageously used for carrying out the selective hydrogenation process according to the invention has, for example, the following average composition: about 90% by weight of propylene, and about 1% to 8% by weight of propadiene and methylacetylene, the remainder being essentially propane. In some C3 fractions, 0.1% to 2% by weight of C2 compounds and C4 compounds may also be present.

[0118] The C2-C3 fraction can also be advantageously used for carrying out the selective hydrogenation process according to the invention. It has, for example, the following composition: about 0.1% to 5% by weight of acetylene, about 0.1% to 3% by weight of propadiene and methylacetylene, about 30% by weight of ethylene and about 5% by weight of propylene, the remainder being essentially methane, ethane and propane. The feedstock may also contain 0.1% to 2% by weight of C4 compounds.

[0119] The C4 steam cracking fraction advantageously used for carrying out the selective hydrogenation process according to the invention has, for example, the following average composition by weight: 1% by weight of butane, 46.5% by weight of butene, 51% by weight of butadiene, 1.3% by weight of vinylacetylene and 0.2% by weight of butyne. In some C4 fractions, 0.1% to 2% by weight of C3 compounds and C5 compounds may also be present.

[0120] The C5 steam cracked fraction advantageously used for carrying out the selective hydrogenation process according to the invention has, for example, the following composition: 21% by weight of pentane, 45% by weight of pentenes and 34% by weight of pentadienes.

[0121] The steam cracking gasoline or pyrolysis gasoline advantageously used for the implementation of the selective hydrogenation process according to the invention corresponds to a hydrocarbon fraction having a boiling point generally ranging from 0 to 300° C., preferably ranging from 10 to 250° C. The polyunsaturated hydrocarbons to be hydrogenated present in the steam cracking gasoline are in particular diolefin compounds (butadiene, isoprene, cyclopentadiene, etc.), styrenic compounds (styrene, α-methylstyrene, etc.) and indenic compounds (indene, etc.). The steam cracking gasoline generally contains a C5 to C12 fraction and traces of a C3 fraction, a C4 fraction, a C13 fraction, a C14 fraction and a C15 fraction (for example, for each of these fractions, it is 0.1% to 3% by weight). For example, the feedstock formed from pyrolysis gasoline generally has the following composition: 5 to 30% by weight of saturated compounds (paraffins and cycloalkanes), 40 to 80% by weight of aromatic compounds, 5 to 20% by weight of monoolefins, 5 to 40% by weight of diolefins, and 1 to 20% by weight of alkenyl aromatic compounds, the combined compounds constituting 100%. It also contains 0 to 1000 ppm by weight of sulfur, preferably 0 to 500 ppm by weight of sulfur.

[0122] Preferably, the polyunsaturated hydrocarbon feedstock treated according to the selective hydrogenation process of the present invention is a C2 steam cracking fraction, or a C2-C3 steam cracking fraction, or a steam cracking gasoline.

[0123] The selective hydrogenation process according to the present invention is intended to remove the polyunsaturated hydrocarbons present in the feedstock to be hydrogenated without hydrogenating monounsaturated hydrocarbons. For example, when the feedstock is a C2 fraction, the selective hydrogenation process is intended to selectively hydrogenate acetylene. When the feedstock is a C3 fraction, the selective hydrogenation process is intended to selectively hydrogenate propadiene and methylacetylene. In the case of a C4 fraction, the goal is to remove butadiene, vinyl acetylene (VAC) and butyne; in the case of a C5 fraction, the goal is to remove pentadiene. When the feedstock is steam cracking gasoline, the selective hydrogenation process is intended to selectively hydrogenate the polyunsaturated hydrocarbons present in the feedstock to be treated, thereby partially hydrogenating the diene compounds to produce monoolefins, and thereby partially hydrogenating the styrene compounds and indenes to produce the corresponding aromatic compounds, while avoiding the hydrogenation of aromatic rings.

[0124] The technical implementation of the selective hydrogenation method is implemented by, for example, injecting a polyunsaturated hydrocarbon feedstock and hydrogen into at least one fixed bed reactor in an upflow mode or a downflow mode. The reactor can be isothermal or adiabatic. Adiabatic reactors are preferred. The polyunsaturated hydrocarbon feedstock can be advantageously diluted by one or more re-injections of the effluent obtained by the reactor in which the selective hydrogenation reaction occurs at various points of the reactor between the inlet and the outlet of the reactor to limit the temperature gradient in the reactor. The technical implementation of the selective hydrogenation method according to the present invention can also be advantageously implemented by loading at least the supported catalyst in a reactive distillation column or a reactor-exchanger or in a slurry-type reactor. The hydrogen stream can be introduced simultaneously with the feedstock to be hydrogenated and / or introduced at one or more different points in the reactor.

[0125] The selective hydrogenation of the C2, C2-C3, C3, C4, C5 and C5+ steam cracking fractions can be carried out in the gas phase or in the liquid phase, preferably in the liquid phase for the C3, C4, C5 and C5+ fractions and in the gas phase for the C2 and C2-C3 fractions. Liquid phase reactions make it possible to reduce energy costs and increase the cycle time of the catalyst.

[0126] Typically, the selective hydrogenation of a hydrocarbon feedstock containing polyunsaturated compounds containing at least 2 carbon atoms per molecule and having a final boiling point lower than or equal to 300° C. is carried out at a temperature of 0 to 300° C., a pressure of 0.1 to 10 MPa, for a process carried out in the liquid phase, at a hydrogen / (polyunsaturated compound to be hydrogenated) molar ratio of 0.1 to 10 and a pressure of 0.1 to 200 h -1 The process is carried out at an hourly space velocity (defined as the ratio of the volume flow of the feed to the volume of the catalyst) of 0.5 to 1000, or, for a process carried out in the gas phase, at a hydrogen / (polyunsaturated compound to be hydrogenated) molar ratio of 0.5 to 1000 and a flow rate of 100 to 40000 h / s. -1 It is implemented at a time and space speed of.

[0127] In one embodiment according to the invention, when implementing a selective hydrogenation process in which the feedstock is a steam cracked gasoline containing polyunsaturated compounds, the (hydrogen) / (polyunsaturated compound to be hydrogenated) molar ratio is generally from 0.5 to 10, preferably from 0.7 to 5.0, and still more preferably from 1.0 to 2.0, the temperature is from 0° C. to 200° C., preferably from 20° C. to 200° C., and still more preferably from 30° C. to 180° C., the hourly space velocity (HSV) is generally from 0.5 to 100 h -1 , preferably 1 to 50h -1 , and the pressure is usually 0.3 to 8.0 MPa, preferably 1.0 to 7.0 MPa, and still more preferably 1.5 to 4.0 MPa.

[0128] More preferably, the selective hydrogenation process is carried out in which the feedstock is a steam cracked gasoline containing polyunsaturated compounds, the hydrogen / (polyunsaturated compounds to be hydrogenated) molar ratio is from 0.7 to

[0129] 5.0, temperature is 20℃ to 200℃, hourly space velocity (HSV) is usually 1 to 50h -1 , and pressure is 1.0 to 7.0MPa.

[0130] Still more preferably, the selective hydrogenation process is carried out in which the feedstock is a steam cracked gasoline containing polyunsaturated compounds, the hydrogen / (polyunsaturated compounds to be hydrogenated) molar ratio is from 1.0 to 2.0, the temperature is from 30° C. to 180° C., the hourly space velocity (HSV) is generally from 1 to 50 h -1 , pressure is 1.5 to 4.0MPa.

[0131] The hydrogen flow rate is adjusted so as to have an amount sufficient to theoretically hydrogenate all the polyunsaturated compounds and to maintain an excess of hydrogen at the reactor outlet.

[0132] In another embodiment according to the present invention, when implementing a selective hydrogenation process in which the feedstock is a C2 steam cracked fraction and / or a C2 to C3 steam cracked fraction containing polyunsaturated compounds, the (hydrogen) / (polyunsaturated compound to be hydrogenated) molar ratio is generally from 0.5 to 1000, preferably from 0.7 to 800, the temperature is from 0° C. to 300° C., preferably from 15 to 280° C., the hourly space velocity (HSV) is generally from 100 to 40000 h -1 , preferably 500 to 30000h -1 , and the pressure is usually 0.1 to 6.0 MPa, preferably 0.2 to 5.0 MPa.

[0133] 6. Hydrogenation method of aromatic compounds

[0134] Another subject of the invention is a process for hydrogenating at least one aromatic or polyaromatic compound contained in a hydrocarbon feedstock having a final boiling point lower than or equal to 650° C., generally ranging from 20° C. to 650° C. and preferably ranging from 20° C. to 450° C. The hydrocarbon feedstock containing at least one aromatic or polyaromatic compound may be chosen from the following petroleum or petrochemical fractions: reformates from catalytic reforming, kerosene, light gas oils, heavy gas oils, cracked distillates, such as FCC recycle oils, coker unit gas oils or hydrocracked distillates.

[0135] The content of aromatic or polyaromatic compounds contained in the hydrocarbon feedstock treated in the hydrogenation process according to the invention is generally from 0.1% to 80% by weight, preferably from 1% to 50% by weight, and particularly preferably from 2% to 35% by weight, the percentages being based on the total weight of the hydrocarbon feedstock. The aromatic compounds present in the hydrocarbon feedstock are, for example, benzene or alkylaromatic compounds, such as toluene, ethylbenzene, o-xylene, m-xylene or p-xylene, or aromatic compounds having several aromatic rings (polyaromatic compounds), such as naphthalene.

[0136] The sulfur or chlorine content in the feedstock is generally less than 5000 ppm by weight, preferably less than 100 ppm by weight, and particularly preferably less than 10 ppm by weight of sulfur or chlorine.

[0137] The technical implementation of the method for hydrogenating aromatic or polyaromatic compounds is implemented by, for example, injecting hydrocarbon feedstock and hydrogen upflow or downflow into at least one fixed bed reactor. The reactor may be of isothermal or adiabatic type. Adiabatic reactors are preferred. The hydrocarbon feedstock may advantageously be diluted by one or more reinjections of the effluent obtained from the reactor in which the hydrogenation reaction of aromatic compounds occurs at various points of the reactor located between the inlet and the outlet of the reactor to limit the temperature gradient in the reactor. The technical implementation of the method for hydrogenating aromatic compounds according to the present invention may also advantageously be implemented by loading at least the supported catalyst in a reactive distillation column or a reactor-exchanger or in a slurry-type reactor. The hydrogen stream may be introduced simultaneously with the feedstock to be hydrogenated and / or at one or more different points in the reactor.

[0138] The hydrogenation of aromatic or polyaromatic compounds can be carried out in the gas phase or in the liquid phase, preferably in the liquid phase. Typically, the hydrogenation of aromatic or polyaromatic compounds of a hydrocarbon feedstock containing aromatic or polyaromatic compounds and having a final boiling point lower than or equal to 650°C, typically 20°C to 650°C, and preferably 20°C to 450°C is carried out at a temperature of 30°C to 350°C, preferably 50°C to 325°C, at a pressure of 0.1 to 20 MPa, preferably 0.5 to 10 MPa, a hydrogen / (aromatic compound to be hydrogenated) molar ratio of 0.1 to 10, and at a temperature of 0.05 to 50 h -1 , preferably 0.1 to 10h -1It is carried out at a time and space speed of .

[0139] The hydrogen flow rate is adjusted so as to have an amount sufficient to theoretically hydrogenate all the aromatic compounds and to maintain an excess of hydrogen at the reactor outlet.

[0140] The conversion of the aromatic or polyaromatic compounds is generally greater than 20 mol%, preferably greater than 40 mol%, more preferably greater than 80 mol%, and particularly preferably greater than 90 mol% of the aromatic or polyaromatic compounds contained in the hydrocarbon feedstock. The conversion is calculated by dividing the difference between the total number of moles of aromatic or polyaromatic compounds in the hydrocarbon feedstock and the total number of moles of aromatic or polyaromatic compounds in the product by the total number of moles of aromatic or polyaromatic compounds in the hydrocarbon feedstock.

[0141] According to a particular variant of the process according to the invention, a process for hydrogenating benzene in a hydrocarbon feedstock, such as a reformate produced by a catalytic reforming unit, is carried out. The benzene content in the hydrocarbon feedstock is generally from 0.1% to 40% by weight, preferably from 0.5% to 35% by weight, and particularly preferably from 2% to 30% by weight, the weight percentages being based on the total weight of the hydrocarbon feedstock.

[0142] The content of sulfur or chlorine in the feedstock is generally less than 10 ppm by weight, and preferably less than 2 ppm by weight, of sulfur or chlorine, respectively.

[0143] The hydrogenation of benzene contained in the hydrocarbon feedstock can be carried out in the gas phase or the liquid phase, preferably in the liquid phase. When it is carried out in the liquid phase, a solvent such as cyclohexane, heptane or octane may be present. Typically, the hydrogenation of benzene is carried out at a temperature of 30 to 250° C., preferably 50 to 200° C., and more preferably 80° C. to 180° C., at a pressure of 0.1 to 10 MPa, preferably 0.5 to 4 MPa, a hydrogen / (benzene) molar ratio of 0.1 to 10, and at a temperature of 0.05 to 50 h -1 , preferably 0.5 to 10h -1 It is carried out at a time and space speed of .

[0144] The conversion of benzene is usually greater than 50 mol %, preferably greater than 80 mol %, more preferably greater than 90 mol %, and particularly preferably greater than 98 mol %.

[0145] The invention will now be illustrated by the following examples, which are not limiting in any way. Example

[0146] For all catalysts mentioned in the examples mentioned below, the support was alumina A with a specific surface area of ​​180 m 2 / g, the pore volume is 0.7 ml / g, and the median mesopore diameter is 10 nm.

[0147] Example 1: Preparation of an aqueous solution S1 of a first Ni precursor and a first organic compound

[0148] By mixing 58g of nickel nitrate (NiNO3 from Strem Supply) and 14.35g malonic acid (CAS 141-82-2; The aqueous solution S1 was prepared by dissolving (supplied) in 42 ml of distilled water. The solution was heated to 60° C. to promote the dissolution of nickel nitrate. The additive / Ni molar ratio was fixed at 0.4 mol / mol. Solution S1 was obtained.

[0149] Example 2: Preparation of an aqueous solution S2 of a NiCu alloy (5 wt% Ni) precursor but without a second organic compound

[0150] An aqueous solution (solution S2) of a precursor of a NiCu alloy for preparing a NiCu-containing catalyst was prepared by mixing 14.5 g of nickel nitrate (NiNO3, supplier: Strem ) was dissolved in a volume of 13 ml of distilled water. A solution having a nickel concentration of 116.6 g Ni per liter of solution was obtained. A copper nitrate precursor was then added to give a Ni / Cu molar ratio of 1.

[0151] Solution S2 is obtained. This makes it possible to introduce a precursor of a NiCu alloy whose Ni content, relative to the weight of the final catalyst, is 5% by weight, relative to the total weight of the catalyst.

[0152] Example 3: Preparation of an aqueous solution S3 of a NiCu alloy precursor and a second organic compound (5 wt % Ni)

[0153] The aqueous solution of NiCu alloy precursor (solution S3) for preparing the NiCu-containing catalyst was prepared by mixing 14.5 g of nickel nitrate (NiNO3, supplier Strem ) was dissolved in 13 ml of distilled water. A solution having a Ni concentration of 116.6 g Ni per liter of solution was obtained. A copper nitrate precursor was then added to give a Ni / Cu molar ratio of 1. Malonic acid was also added to the solution to give an additive / Ni molar ratio of 0.90 mol / mol.

[0154] A solution S3 is obtained. It makes it possible to introduce a precursor of a NiCu alloy in which the weight content of Ni, relative to the final catalyst, is 5% by weight of the total weight of the catalyst.

[0155] Example 4: Preparation of Catalyst A (not according to the invention—without second organic compound)

[0156] 10 g of aluminum oxide A were dry impregnated with 7.1 ml of solution S1. The catalyst precursor obtained was subsequently dried in an oven at 120° C. for 12 hours and then calcined at 450° C. for 2 hours under a dry air stream of 1 l / h / g catalyst. Next, dry impregnation was carried out by dropwise addition of 10 ml of solution S2 prepared in Example 2. The solid thus obtained was subsequently dried in an oven at 120° C. for 12 hours and then calcined at 450° C. for 2 hours under a dry air stream of 1 l / h / g catalyst.

[0157] Catalyst A was obtained, which contained 24 wt% of nickel element (including 5 wt% of nickel element in the NiCu alloy) relative to the total weight of the catalyst. The characteristics of the catalyst A thus obtained are given in Table 1 below.

[0158] Example 5: Preparation of Catalyst B (not according to the invention—without second organic compound)

[0159] 10 g of aluminum oxide A are dry impregnated with 7.1 ml of solution S1. The catalyst precursor obtained is subsequently dried in an oven at 120° C. for 12 hours and then calcined at 450° C. for 2 hours under a dry air stream of 1 l / h / g catalyst. The intermediate catalyst impregnated again is then dried with 7.1 ml of solution S1. The catalyst precursor obtained is subsequently dried in an oven at 120° C. for 12 hours and then calcined at 450° C. for 2 hours under a dry air stream of 1 l / h / g catalyst. Next, dry impregnation is carried out by dropwise addition of 10 ml of solution S2 prepared in Example 2. The solid thus obtained is subsequently dried in an oven at 120° C. for 12 hours and then calcined at 450° C. for 2 hours under a dry air stream of 1 l / h / g catalyst.

[0160] Catalyst B was obtained, which contained 27 wt% of nickel element (including 5 wt% of nickel element in the NiCu alloy) relative to the total weight of the catalyst. The characteristics of the catalyst B thus obtained are given in Table 1 below.

[0161] Example 6: Preparation of Catalyst C (according to the present invention)

[0162] 10 g of aluminum oxide A were dry impregnated with 7.1 ml of solution S1. The catalyst precursor obtained was subsequently dried in an oven at 120° C. for 12 hours and then calcined at 450° C. for 2 hours under a dry air stream of 1 l / h / g catalyst. Next, dry impregnation was carried out by dropwise addition of 10 ml of solution S3 prepared in Example 3. The molar ratio between the second organic compound / Ni (NiCu solution, solution S2) and the first organic compound / Ni molar ratio (active Ni solution S1) was 2.25. The solid thus obtained was subsequently dried in an oven at 120° C. for 12 hours and then calcined at 450° C. for 2 hours under a dry air stream of 1 l / h / g catalyst.

[0163] Catalyst C was obtained, which contained 24 wt% of nickel element (including 5 wt% of nickel element in the NiCu alloy) relative to the total weight of the catalyst. The characteristics of the catalyst C thus obtained are given in Table 1 below.

[0164] Example 7: Preparation of Catalyst D (According to the Invention—Double Impregnation)

[0165] 10 g of aluminum oxide A were dry impregnated with 7.1 ml of solution S1. The catalyst precursor obtained was subsequently dried in an oven at 120° C. for 12 hours and then calcined at 450° C. for 2 hours under a dry air stream of 1 l / h / g catalyst. The intermediate catalyst impregnated again was then dried with 7.1 ml of solution S1. The catalyst precursor obtained was subsequently dried in an oven at 120° C. for 12 hours and then calcined at 450° C. for 2 hours under a dry air stream of 1 l / h / g catalyst. Dry impregnation was then carried out by dropwise addition of 10 ml of solution S3 prepared in Example 3. The molar ratio between the second organic compound / Ni (NiCu solution, solution S2) and the first organic compound / Ni molar ratio (active Ni solution S1) was 2.25. The solid thus obtained was subsequently dried in an oven at 120° C. for 12 hours and then calcined at 450° C. for 2 hours under a dry air stream of 1 l / h / g catalyst.

[0166] Catalyst D was obtained, which contained 27 wt% of nickel element (including 5 wt% of nickel element in the NiCu alloy) relative to the total weight of the catalyst. The characteristics of the catalyst D thus obtained are given in Table 1 below.

[0167] Example 8: Preparation of Catalyst E (not according to the invention—without NiCu and without second organic compound)

[0168] 10 g of aluminum oxide A are dry-impregnated with 7.1 ml of solution S1. The catalyst precursor obtained is subsequently dried in an oven at 120° C. for 12 hours and then calcined at 450° C. for 2 hours under a dry air stream of 1 l / h / g catalyst. The re-impregnated intermediate catalyst is then dried with 7.1 ml of solution S1. The catalyst precursor thus obtained is subsequently dried in an oven at 120° C. for 12 hours and then calcined at 450° C. for 2 hours under a dry air stream of 1 l / h / g catalyst.

[0169] Catalyst E was obtained, which contained 22% by weight of nickel element relative to the total weight of the catalyst. The characteristics of the catalyst E thus obtained are given in Table 1 below.

[0170] Table 1

[0171] catalyst Second organic compound Ni°(wt%)* Particle size (nm) A (not according to the invention) none 19 6 B (not according to the invention) none 22 9 C (according to the present invention) have 19 2.5 D (according to the present invention) have 22 3 E (not according to the invention) None (NiCu free) 22 5

[0172] *Ni 0 Excluding NiCu alloys

[0173] Example 9: Characterization

[0174] The amount of alloy obtained after the calcination step and then the reduction step is determined by X-ray diffraction (XRD) analysis on a sample of the catalyst in powder form.

[0175] The amount of nickel obtained in metallic form after the reduction step was determined by X-ray diffraction (XRD) analysis on a sample of the catalyst in powder form. Between the reduction step and the entire process of characterization by XRD, the catalyst was never returned to open air. The nickel content was determined by using a conventional powder method with the aid of a diffractometer, using copper Kα1 radiation. The diffraction pattern was obtained by radioactive crystal analysis.

[0176] The Ni concentrations located near 52° 2θ in all diffraction patterns of each catalyst sample analyzed were calculated. 0 The degree of reduction is then calculated by subtracting the signal (caused by alumina) present below the 52° line as soon as ambient temperature is reached from the area of ​​the line.

[0177] Table 2 below summarizes the reduction degree or nickel metal Ni characterized by XRD after all catalysts A to E were reduced under hydrogen flow at 170° C. for 190 minutes. 0 The contents of Ni (expressed in wt. % relative to the total weight of "active" Ni not constituting an alloy) are also compared with the degree of reduction obtained for Catalyst E (nickel only) after a conventional reduction step, i.e. at a temperature of 400° C. for 15 hours under a stream of hydrogen.

[0178] At ambient temperature, delta and theta alumina as well as large CuO and NiO lines were detected on all copper- and nickel-containing catalysts after calcination.

[0179] In addition, the corresponding Ni 0.76 Cu 0.24 In the form of alloy wire.

[0180] In order to evaluate the degree of reduction and thus Ni 0 The formation of Ni near 52°2θ in all diffraction patterns was measured. 0 The area of ​​the line is determined by subtracting the signal (caused by alumina) that appears below the 52° line as soon as ambient temperature is reached. 0 The relative percentage of .

[0181] Table 2

[0182]

[0183] *Nickel is in the form of NiO.

[0184] For Catalyst E (22% Ni / alumina only), the degree of nickel reduction was 0% after the reduction treatment under hydrogen in exactly the same manner as Catalysts A, B, C, and D. It was necessary to reduce Catalyst E at 400°C to reduce the nickel oxide to Ni 0 The degree of reduction is about 80%.

[0185] Example 10: Catalytic Test: Selective Hydrogenation Performance of a Mixture Containing Styrene and Isoprene (A HYD1 )

[0186] Catalysts A to E described in the above examples were tested for the selective hydrogenation of a mixture containing styrene and isoprene.

[0187] The composition of the feedstock to be selectively hydrogenated was as follows: 8 wt% styrene (supplier Sigma Purity 99%), 8 wt% isoprene (supplier Sigma Purity 99%) and 84 wt% n-heptane (solvent) (supplier Purity>99% ChromanormHPLC). This composition corresponds to the initial composition of the reaction mixture. This mixture of model molecules represents pyrolysis gasoline.

[0188] The selective hydrogenation reactions were carried out in a 500 ml stainless steel autoclave equipped with a magnetically driven mechanical stirrer and capable of operating at a maximum pressure of 100 bar (10 MPa) and a temperature range of 5°C to 200°C.

[0189] 214 ml of n-heptane (from Supply, purity> 99% Chromanorm HPLC) and 3ml amount of catalyst are added to the autoclave. Close the autoclave and purge. Then the autoclave is pressurized under 35 bar (3.5MPa) of hydrogen. First, at 170 ℃, under a hydrogen stream of 1l / h / g, catalyst A to catalyst E are in situ reduced for 90 minutes (temperature gradient is 1 ℃ / minute) (this is equivalent to step f of one embodiment of the preparation method according to the present invention). Then the autoclave is brought to the test temperature, which is equal to 30 ℃. At time t=0, about 30g of a mixture containing styrene, isoprene, n-heptane, pentamethylene mercaptan and thiophene is introduced into the autoclave. Then, the reaction mixture has the above composition and starts stirring at 1600rpm. The pressure in the autoclave is kept constant at 35 bar (3.5MPa) using a gas storage tank located upstream of the reactor.

[0190] Another test was performed on Catalyst E, but the catalyst reduction temperature was 400°C for 15 hours.

[0191] The progress of the reaction is monitored by sampling the reaction medium at regular intervals: styrene is hydrogenated to produce ethylbenzene, without hydrogenating the aromatic rings, and isoprene is hydrogenated to produce methylbutene. If the reaction is prolonged beyond the necessary time, the methylbutene is in turn hydrogenated to produce isopentane. The consumption of hydrogen is also monitored over time by the decrease in pressure in a gas tank located upstream of the reactor. The catalytic activity is expressed in moles of H2 consumed per minute and per gram of Ni.

[0192] Table 3 below reports the measured catalytic activities of Catalysts A to E. They are compared with the catalytic activity (A) measured for Catalyst E prepared under conventional reduction conditions (reduction at a temperature of 400° C. under a hydrogen stream for 15 hours). HYD1 ) is associated with.

[0193] Example 11: Catalytic test: Toluene hydrogenation performance (A HYD2 )

[0194] Catalysts A to E described in the above examples were also tested for the hydrogenation of toluene. The selective hydrogenation reaction was carried out in the same autoclave as described in Example 10.

[0195] 214 ml of n-heptane (from The catalyst (supplied by Chromanorm HPLC, purity> 99%) and 3 ml of the catalyst were added to the autoclave. The autoclave was closed and purged. The autoclave was then pressurized under 35 bar (3.5 MPa) of hydrogen. First, at 170° C., under a hydrogen flow of 1 l / h / g, catalysts A to E were in situ reduced for 90 minutes (temperature gradient of 1° C. / min) (this corresponds to step f of one embodiment of the preparation method according to the present invention). After adding 216 ml of n-heptane (supplied by After purity >99% Chromanorm HPLC), the autoclave was closed, purged, then pressurized at 35 bar (3.5 MPa) of hydrogen and brought to the test temperature, equal to 80° C. At time t=0, about 26 g of toluene (supplier Purity> 99.8%) was introduced into the autoclave (initial composition of the reaction mixture was 6 wt% toluene / 94 wt% n-heptane) and stirring was started at 1600 rpm. The pressure in the autoclave was kept constant at 35 bar (3.5 MPa) using a gas tank located upstream of the reactor.

[0196] The progress of the reaction is monitored by sampling the reaction medium at regular time intervals: toluene is completely hydrogenated to produce methylcyclohexane. The consumption of hydrogen is also monitored over time by the decrease in pressure in a gas tank located upstream of the reactor. The catalytic activity is expressed in moles of H2 consumed per minute and per gram of Ni.

[0197] Table 3 below reports the measured catalytic activities of Catalysts A to E. They are compared with the catalytic activity (A) measured for Catalyst E prepared under conventional reduction conditions (reduction at a temperature of 400° C. under a hydrogen stream for 15 hours). HYD1 ) is associated with.

[0198] Table 3

[0199]

[0200]

[0201] These results clearly show that the A of catalysts C and D obtained by the preparation method according to the invention is higher than that of catalysts A, B and E not according to the invention. HYD1 and A HYD2 The performance is significantly improved. For catalysts A and B, nickel oxide is reduced by 90% at 170°C and its particles grow during the NiCu impregnation step without the presence of a second organic compound. The activity of catalyst E is reduced due to the lack of NiCu, so the reducibility of NiO at 170°C is almost zero. Compared to the precursor with the addition of nickel active phase, catalysts C and D maintain small nickel particles due to the addition of malonic acid (second organic compound) during the post-treatment of adding NiCu.

Claims

1. A method for preparing a catalyst comprising nickel and copper and a porous alumina carrier, wherein the proportion of nickel element relative to the total weight of the catalyst is 1 wt % to 50 wt %, and the proportion of copper element relative to the total weight of the catalyst is 0.5 wt % to 15 wt %, and the size of the nickel particles in the catalyst measured in the form of oxide is less than 5 nm, the method comprising at least the following steps: a) contacting the alumina support with at least one solution containing at least one first nickel precursor and at least one first organic compound comprising at least one carboxylic acid functional group to obtain a first catalyst precursor; b) drying the first catalyst precursor obtained at the end of step a) at a temperature of less than 250° C. and then calcining the dried first catalyst precursor at a temperature ranging from 250° C. to 550° C. to obtain a calcined catalyst precursor; c) contacting the calcined catalyst precursor obtained at the end of step b) with at least one solution containing at least one second nickel precursor, at least one copper precursor and at least one second organic compound comprising at least one carboxylic acid functional group, so as to obtain a second catalyst precursor; d) drying the second catalyst precursor obtained at the end of step c) at a temperature of less than 250°C.

2. The method as claimed in claim 1, wherein the molar ratio between the organic compound introduced in step a) and the nickel element also introduced in step a) is 0.01 to 5.0 mol / mol.

3. A process as claimed in one of claims 1 and 2, wherein the molar ratio between the organic compound introduced in step c) and the nickel element also introduced in step c) is 0.02 to 5 mol / mol.

4. A process as claimed in any one of claims 1 to 3, wherein the molar ratio between the nickel introduced during steps a) and c) and the copper introduced in step c) is from 0.5 to 5 mol / mol.

5. A process as claimed in any one of claims 1 to 4, wherein the ratio between the molar ratio between the second organic compound introduced in step c) and the nickel and the molar ratio between the first organic compound introduced in step a) and the nickel is greater than 1.

5.

6. A process as claimed in any one of claims 1 to 5, wherein steps a) and b) are carried out at least twice before carrying out step c).

7. A process as claimed in any one of claims 1 to 6, wherein the first organic compound of step a) and the second organic compound of step c) are selected from oxalic acid, malonic acid, glycolic acid, lactic acid, tartronic acid, citric acid, tartaric acid, pyruvic acid and levulinic acid.

8. A process as claimed in any one of claims 1 to 7, wherein the first organic compound of step a) and the second organic compound of step c) are identical.

9. A method as claimed in any one of claims 1 to 8, wherein the copper precursor is selected from copper acetate, copper acetylacetonate, copper nitrate, copper sulfate, copper chloride, copper bromide, copper iodide and copper fluoride.

10. A method as claimed in any one of claims 1 to 9, wherein the first nickel precursor and / or the second nickel precursor is nickel nitrate, nickel chloride, nickel acetate or nickel hydroxycarbonate.

11. A process as claimed in any one of claims 1 to 10, further comprising a step e) in which the catalyst obtained at the end of step d) is calcined at a temperature ranging from 250°C to 550°C.

12. A process as claimed in any one of claims 1 to 11, further comprising a step f) in which the catalyst obtained at the end of step d), optionally at the end of step e), is reduced by contacting the catalyst with a reducing gas at a temperature greater than or equal to 150°C and less than 250°C.

13. A catalyst obtained by the process as claimed in any one of claims 1 to 12, the catalyst comprising nickel and copper and a porous alumina carrier, the proportion of nickel element relative to the total weight of the catalyst being 1 wt% to 50 wt%, and the proportion of copper element relative to the total weight of the catalyst being 0.5 wt% to 15 wt%, the size of the nickel particles in the catalyst measured in oxide form being less than 5 nm.

14. A process for the selective hydrogenation of polyunsaturated compounds having at least 2 carbon atoms per molecule contained in a hydrocarbon feedstock having a final boiling point lower than or equal to 300° C., in the presence of a catalyst as claimed in claim 13 or a catalyst obtained by a preparation process as claimed in any one of claims 1 to 12, at a temperature of 0° C. to 300° C., a pressure of 0.1 to 10 MPa, when the process is carried out in the liquid phase, at a hydrogen / (polyunsaturated compound to be hydrogenated) molar ratio of 0.1 to 10 and a pressure of 0.1 to 200 h. -1 or, when the process is carried out in the gas phase, at a hydrogen / (polyunsaturated compound to be hydrogenated) molar ratio of 0.5 to 1000 and a heating rate of 100 to 40000 h / s. -1 It is implemented at a time and space speed of.

15. A process for hydrogenating at least one aromatic or polyaromatic compound contained in a hydrocarbon feedstock having a final boiling point lower than or equal to 650° C., in the presence of a catalyst as claimed in claim 13 or a catalyst obtained by a preparation process as claimed in any one of claims 1 to 12, in the gas phase or liquid phase, at a temperature of 30 to 350° C., a pressure of 0.1 to 20 MPa, a hydrogen / (aromatic compound to be hydrogenated) molar ratio of 0.1 to 10 and a reaction temperature of 0.05 to 50 h. -1 It is implemented at a time and space speed of.

Images