HYDROGENATION PROCESS USING A CATALYST COMPRISING COPPER AND AN ELEMENT OF COLUMN IIIA

Abstract

Selective hydrogenation process of polyunsaturated compounds containing at least 2 carbon atoms per molecule contained in a hydrocarbon feedstock having a final boiling point of less than or equal to 300°C, in the presence of a catalyst comprising an active phase comprising copper and an element of column IIIA, and an alumina support, the copper content being between 0.5% and 25% by weight as element copper relative to the total weight of the catalyst, the atomic ratio between copper and the element of column IIIA being between 1 and 50 mol / mol, said catalyst being in the form of a powder with a particle size between 20 µm and 500 µm.

Description

Title of the invention: HYDROGENATION PROCESS USING A CATALYST COMPRISING COPPER AND AN ELEMENT OF COLUMN IIIA technical field

[0001] The invention relates to a process for hydrogenating unsaturated hydrocarbons, and more particularly, for the selective hydrogenation of polyunsaturated compounds carried out in the presence of a metallic catalyst in the form of a copper-based powder and an element from column IIIA, chosen from indium and gallium. State of the art

[0002] Monounsaturated organic compounds, such as ethylene and propylene, are the basis for the manufacture of polymers, plastics, and other value-added chemicals. These compounds are obtained from natural gas, naphtha, or diesel fuel that has been treated by steam cracking or catalytic cracking processes. These processes are carried out at high temperatures and produce, in addition to the desired monounsaturated compounds, 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 whose boiling point corresponds to the C5+ gasoline fraction (gasoline containing hydrocarbon compounds having 5 or more carbon atoms), in particular styrenic or indenic compounds.These polyunsaturated compounds are highly reactive and lead to unwanted reactions in the polymerization units. It is therefore necessary to remove them before processing these fragments.

[0003] Selective hydrogenation is the main treatment developed to specifically remove undesirable polyunsaturated compounds from these hydrocarbon feedstocks. It allows the conversion of polyunsaturated compounds to the corresponding alkenes or aromatics while avoiding their total saturation and thus the formation of the corresponding alkanes or naphthenes.

[0004] Selective hydrogenation catalysts are generally based on metals from group VIII of the periodic table, preferably palladium or nickel. The metal is in the form of metallic particles deposited on a support. The metal content, the size of the metal particles, and the distribution of the active phase within the support are among the criteria that are important for the activity and selectivity of the catalysts.

[0005] Palladium-based catalysts are widely used in the selective hydrogenation reactions of light C2-C4 cuts.

[0006] Typically, the palladium content is low, generally less than 1% by weight of palladium relative to the catalyst. The palladium is distributed in a crust on the periphery of the catalyst (egg-shell catalyst according to Anglo-Saxon terminology, for example described in FR2922784 or US2010 / 217052).

[0007] Recent years have seen an increase in the price of noble metals, in particular gold, ruthenium, platinum and palladium, and have led to the search for metallic or multimetallic catalysts containing non-noble metals for the hydrogenation of acetylenics and diolefins.

[0008] Thus, the publication by Wang et al. (Chem. Commun., 2021,57, 7031-7034) describes the use of a catalyst comprising iron supported on a titanium oxide for the selective hydrogenation of butadiene into alkenes at 175°C.

[0009] Patent application CN110433813A (2019) discloses the use of a catalyst containing a CuIn / ZrO2 alloy for the hydrogenation of CO2 to methanol. The catalyst is prepared by co-precipitation of precursors of the three elements.

[0010] Patent application CN114054024A (2021) discloses the preparation of a catalyst for the hydrogenation of dimethyl oxalate containing an active phase based on Cu supplemented by another metal (or in oxide form) selected from Ni, In, Mo, W, Fe and Zn with a ratio of 0.2-1.5 based on the metal on a SiO2 support.

[0011] The publication by Onyestyak et al. (Catalysis Communications, 2012, 26, 19-24) describes the use of a Culn catalyst on gamma Al₂O₃ comprising between 3 and 20% Cu and between 3-20% In introduced by mechanical mixing for the hydrogenation of organic acids. The catalyst is in powder form. The specific surface area of ​​the support is 203 m² / g.

[0012] The publication by Zhang et al. (Chinese Journal of Catalysis, 2018, 39, 99-108) describes the use of a Culn catalyst on SiO2 for the hydrogenation of methyl acetate to ethanol. The addition of 0.2-2% indium is carried out on a catalyst comprising 30% Cu / SiO2, corresponding to a Cu / In molar ratio greater than 66 mol / mol.

[0013] The publication by Dong et al. (Applied Catalysis B: Environmental, 2018, 244) describes the use of a catalyst comprising 10% Cu on an SBA15 type silica and indium such that the Cu / In ratio is between 0.01 and 15 to hydrogenate acetic acid into ethanol.

[0014] Surprisingly, the Applicant discovered that a catalyst comprising copper and a selected element from column III A, preferably chosen from indium and gallium, and an alumina support in powder form allows for performance in terms of activity in selective hydrogenation of polyunsaturated compounds at least as good, or even better, than known prior art processes. Objects of the invention

[0015] A first object 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 less than or equal to 300°C, which process is carried out at a temperature between 0 and 300°C, at a pressure between 0.1 MPa and 10 MPa, at a molar ratio of hydrogen / (polyunsaturated compounds to be hydrogenated) between 0.1 and 10 and at a volumetric rate per hour between 0.1 and 200 h⁻¹ when the process is carried out in the liquid phase, or at a molar ratio of hydrogen / (polyunsaturated compounds to be hydrogenated) between 0.5 and 1000 and at a volumetric rate per hour between 100 and 40,000 h⁻¹ when the process is carried out in the gas phase, in the presence of a catalyst comprising an active phase including copper and a element of column IIIA, and an alumina support, the copper content being between 0,5% and 25% by weight of copper relative to the total weight of the catalyst, the atomic ratio between copper and the element of column IIIA being between 1 and 50 mol / mol, said catalyst being in the form of a powder with a particle size between 20 µm and 500 µm.

[0016] According to one or more embodiments of the invention, the element of column III A is chosen from indium or gallium.

[0017] According to one or more embodiments of the invention, when element IIIA is indium, the indium content is between 0.02% and 25% by weight of indium element relative to the total weight of the catalyst.

[0018] According to one or more embodiments of the invention, when element IIIA is gallium, the gallium content is between 0.5% and 25% by weight of gallium element relative to the total weight of the catalyst.

[0019] According to one or more embodiments of the invention, the specific surface area of ​​the catalyst used is between 80 and 200 m2 / g.

[0020] Another object according to the invention relates to a process according to the invention in which said catalyst is obtained by a preparation process comprising the following steps:

[0021] a) a catalyst precursor is formed by carrying out the following sequence:

[0022] al) an alumina powder is brought into contact with a solution comprising at least one precursor of the active copper phase;

[0023] a2) the alumina powder is contacted with at least one solution comprising at minus a precursor of the active phase based on an element of column IIIA;

[0024] steps a1) and a2) being carried out separately, in any order, or simultaneously;

[0025] b) the catalyst precursor obtained at the end of step a) is dried at a temp- temperature below 250°C to obtain a dried catalyst precursor.

[0026] According to one or more embodiments of the invention, when steps a1) and a2) are carried out separately, an intermediate drying step is carried out between steps a1) and a2), or between steps a2) and a1), in which the catalyst precursor obtained at the end of step a1), or of step a2), is dried at a temperature below 250°C.

[0027] According to one or more embodiments of the invention, the catalyst precursor obtained at the end of the intermediate drying step is subjected to heat treatment at a temperature between 250°C and 1000°C.

[0028] According to one or more embodiments of the invention, steps a1) and a2) are carried out simultaneously.

[0029] According to one or more embodiments of the invention, the precursor of the active copper phase is chosen from copper acetate, copper acetylacetonate, copper nitrate, copper sulfate, copper chloride, copper bromide, copper iodide or copper fluoride.

[0030] According to one or more embodiments of the invention, element IIIA of the active phase is indium, and wherein the indium precursor is selected from indium acetate, indium acetylacetonate, indium nitrate, indium sulfate, indium sulfide, indium chloride, indium mercaptoacetate, indium bromide, indium iodide, indium fluoride, indium oxide, indium phosphide, indium hydroxide.

[0031] According to one or more embodiments of the invention, element IIIA of the active phase is gallium, and in which the gallium precursor is chosen gallium acetylacetonate, gallium nitrate, gallium sulfate, gallium sulfide, gallium chloride, gallium bromide, gallium iodide, gallium oxide, gallium nitride, gallium phosphide, gallium perchlorate, organics such as gallium triethyl and gallium trimethyl. Detailed description of the invention Definitions

[0032] In the following, the groups of chemical elements are given according to the CAS classification (CRC Handbook of Chemistry and Physics, publisher CRC press, editor-in-chief DR Lide, 81st edition, 2000-2001). For example, group IIIA according to the CAS classification corresponds to the metals of column 13 according to the new IUPAC classification.

[0033] The BET specific surface area is measured by nitrogen physisorption. The BET specific surface area is measured by nitrogen physisorption according to ASTM D3663-03 as described in Rouquerol F.; Rouquerol J.; Singh K. “Adsorption by Powders & Porous Solids: Principle, methodology and applications”, Academie Press, 1999.

[0034] The total pore volume is measured by mercury porosimetry according to ASTM D4284-92 with a wetting angle of 140°, for example using an Autopore® III model device from Microméritics®.

[0035] The size of the support and / or catalyst grains is measured using laser scattering particle size analysis. This analytical method utilizes the principle of light scattering (Mie theory) and / or diffraction (Fraunhofer and Mie theories). Particles illuminated by laser light deflect the light from its principal axis. The amount of light deflected and the magnitude of the deflection angle allow for the precise measurement of particle size.

[0036] The copper, indium, and gallium contents are measured by X-ray fluorescence. Catalyst active phase of the catalyst

[0037] The catalyst comprises an active phase comprising copper and an element from column IIIA, an alumina support in powder form, the copper content being between 0.5% and 25% by weight as element copper relative to the total weight of the catalyst, the atomic ratio between copper and the element from column IIIA being between 1 and 50 mol / mol.

[0038] The copper content in the catalyst is between 0.5% and 25% by weight of copper element relative to the total weight of the catalyst, preferably between 1 and 20% by weight, more preferably between 2 and 18% by weight, more preferably between 3 and 15% by weight, even more preferably between 5 and 15% by weight.

[0039] Preferably the element in column IIIA is chosen from indium or gallium.

[0040] The content of the element from column III A in the catalyst is preferably between 0.02% and 25% by weight in column III A element relative to the total weight of the catalyst, preferably between 0.05% and 20% by weight, and even more preferably between 0.1% and 15% by weight.

[0041] When element IIIA is indium, the indium content is preferably between 0.02% and 25% by weight of indium element relative to the total weight of the catalyst, more preferably between 0.05% and 20% by weight, and even more preferably between 0.1% and 15% by weight.

[0042] When element IIIA is gallium, the gallium content is preferably between 0.5% and 25% by weight of element gallium relative to the total weight of the catalyst, more preferably between 0.5% and 20% by weight, and even more preferably between 1% and 15% by weight.

[0043] The atomic ratio between copper and the element in group III A is between 1 and 50 mol / mol, preferably between 10 and 45 mol / mol, and more preferably between 15 and 45 mol / mol, and even more particularly between 18 and 40 mol / mol.

[0044] The catalyst may preferably contain the presence of an alloy containing copper and indium.

[0045] The catalyst is in the form of a powder with a particle size between 20 microns and 500 pm, preferably 25 and 350 pm.

[0046] The average particle size (in size) of metallic crystallites comprising copper and indium is advantageously between 3.5 and 100 nm, preferably between 4 and 50 nm.

[0047] The specific surface area of ​​the catalyst is advantageously between 80 m2 / g and 200 m2 / g, preferably between 90 m2 / g and 180 m2 / g, more preferably between 100 m2 / g and 170 m2 / g, more preferably between 110 m2 / g and 170 m2 / g, more preferably between 120 m2 / g and 160 m2 / g.

[0048] The total porous volume (TPV) of the catalyst is advantageously between 0.1 cmVg and 1.5 cmVg, preferably between 0.2 cmVg and 1.4 cmVg, and even more preferably between 0.25 cmVg and 1.3 cmVg. Catalyst support

[0049] The catalyst support is alumina in powder form, i.e., the support comprises at least 95%, preferably at least 98%, and particularly preferably at least 99% by weight of alumina relative to the weight of the support. The alumina generally has a crystallographic structure of the delta, gamma, or theta type, alone or in mixtures.

[0050] Preferably, alumina is present predominantly in gamma form.

[0051] According to the invention, the alumina support may include impurities such as metal oxides of groups IIA, IIIB, IVB, IIB, IIIA, IVA according to the CAS classification, preferably silica, 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.

[0052] The specific surface area of ​​the support is between 80 m² / g and 200 m² / g, preferably between 90 m² / g and 180 m² / g, more preferably between 100 m² / g and 170 m² / g, more preferably between 110 m² / g and 170 m² / g, and more preferably between 120 m² / g and 160 m² / g.

[0053] The total porous volume (TPV) of the porous support is advantageously between 0.1 cmVg and 1.5 cmVg, preferably between 0.2 cmVg and 1.4 cmVg, and even more preferably between 0.25 cmVg and 1.3 cmVg.

[0054] The porous support is in the form of a powder with a particle size between 20 pm and 500 pm, preferably 25 pm and 350 pm. Catalyst preparation

[0055] According to the invention, the catalyst preparation process comprises the following steps:

[0056] a) a catalyst precursor is formed by carrying out the following sequence:

[0057] al) an alumina powder is brought into contact with a solution comprising at least one precursor of the active copper phase;

[0058] a2) an alumina powder is contacted with at least one solution comprising at least one precursor of the active phase based on an element of column IIIA;

[0059] steps a1) and a2) being carried out separately, in any order, or simultaneously;

[0060] b) the catalyst precursor obtained at the end of step a) is dried at a temperature below 250°C to obtain a dried catalyst precursor.

[0061] The different steps are explained in detail below.

[0062] Step a) - Contacting the support with a precursor of the active phase of copper and a precursor based on an element of column IIIA.

[0063] In step a), a catalyst precursor is formed by carrying out the following sequence:

[0064] al) an alumina powder is brought into contact with a solution comprising at least one precursor of the active copper phase;

[0065] a2) an alumina powder is brought into contact with at least one solution comprising at least one precursor of the active phase based on an element of column IIIA;

[0066] steps a1) and a2) being carried out separately, in any order, or simultaneously;

[0067] Said step a1) is characterized in that the contacting of the alumina powder with a solution containing a precursor of the copper active phase can be carried out by impregnation, either dry or in excess, or by deposition-precipitation, according to methods well known to those skilled in the art. The pH of said solution can be modified by the optional addition of an acid or a base.

[0068] Said step a1) is preferably carried out by impregnation of the support consisting for example of bringing the alumina powder into contact with at least one aqueous solution containing a copper precursor.

[0069] Preferably, said step a1) is carried out by dry impregnation, which consists of bringing the alumina powder into contact with at least one solution, preferably containing at least one copper precursor, the volume of which is between 0.25 and 1.5 times the porous volume of the support to be impregnated.

[0070] The copper precursor salt is preferably selected from copper acetate, copper acetylacetonate, copper nitrate, copper sulfate, copper chloride copper, copper bromide, copper iodide or copper fluoride.

[0071] Preferably, the copper precursor salt is selected from copper nitrate, copper sulfate or copper chloride.

[0072] The concentration of copper in solution is adjusted according to the type of impregnation (dry or excess impregnation) and the porous volume of the support so as to obtain for the supported catalyst, a copper content of between 0.5% and 25% by weight in copper element relative to the total weight of the catalyst, preferably between 1 and 20% by weight, more preferably between 2 and 18% by weight, more preferably between 3 and 15% by weight, even more preferably between 5 and 15% by weight.

[0073] Said step a2) is characterized in that the contacting of the alumina powder with a solution containing a precursor of at least one precursor of an element of column III A, preferably chosen from indium and gallium, in accordance with the implementation of step b2), can be carried out by impregnation, dry or in excess, or by deposition-precipitation, according to methods well known to the person skilled in the art.

[0074] Said step a2) is preferably carried out by impregnating the alumina powder, for example by contacting the powder with at least one aqueous solution containing a precursor of an element from column III A, preferably chosen from indium and gallium. The pH of said solution can be modified by the optional addition of an acid or a base.

[0075] Preferably, said step a2) is carried out by dry impregnation, which consists of bringing the alumina powder into contact with at least one solution, preferably containing at least one precursor of an element from column III A, preferably chosen from indium and gallium, the volume of which is between 0.25 and 1.5 times the porous volume of the support to be impregnated.

[0076] The indium precursor is preferably chosen from indium acetate, indium acetylacetonate, indium nitrate, indium sulfate, indium sulfide, indium chloride, indium mercaptoacetate, indium bromide, indium iodide, indium fluoride, indium oxide, indium phosphide, indium hydroxide.

[0077] The gallium precursor is chosen gallium acetylacetonate, gallium nitrate, gallium sulfate, gallium sulfide, gallium chloride, gallium bromide, gallium iodide, gallium oxide, gallium nitride, gallium phosphide, gallium perchlorate, organic precursors such as gallium triethyl and gallium trimethyl.

[0078] The concentration in solution of the element from column III A, preferably chosen from indium and gallium, is adjusted according to the type of impregnation (dry or excess impregnation) and the porosity volume of the support so as to obtain for the catalyst supported, a content of element of column III A, preferably chosen from indium and gallium of between 0.02% and 25% by weight element of column III A, preferably chosen from indium and gallium in relation to the total weight of the catalyst, preferably between 0.05 and 20% by weight, more preferably between 0.1 and 15% by weight.

[0079] Similarly, the concentration of the element in column III A, preferably chosen from indium and gallium in solution, is supplied so that the atomic ratio between copper and the element in column III A, preferably chosen from indium and gallium, is between 0.5 and 100 mol / mol, preferably between 1 and 80 mol / mol, and more preferably between 1 and 70 mol / mol, and even more particularly between 1 and 50 mol / mol.

[0080] When steps a1) and a2) are carried out separately, an intermediate drying step is performed between steps a1) and a2), or between steps a2) and a1), in which the catalyst precursor obtained at the end of step b1), or step a2), is dried at a temperature below 250°C, preferably between 70°C and 200°C. The drying time is generally between 0.5 hours and 20 hours. Longer drying times are not excluded, but do not necessarily provide any improvement.

[0081] Drying is generally carried out under combustion air of a hydrocarbon, preferably methane, or under heated air comprising between 0 and 80 grams of water per kilogram of combustion air, an oxygen level between 5% and 25% by volume and a carbon dioxide level between 0% and 10% by volume.

[0082] Optionally, the catalyst precursor obtained after the intermediate drying step is subjected to heat treatment under air, preferably combustion air, and more preferably methane combustion air, comprising between 40 and 80 grams of water per kg of air, an oxygen content of between 5% and 15% by volume, and a CO2 content of between 4% and 10% by volume. The calcination temperature is generally between 250°C and 900°C, preferably between approximately 300°C and approximately 500°C. The calcination time is generally between 0.5 hours and 5 hours. The volumetric flow rate per hour (VVH) is generally between 150 and 3000, preferably between 300 and 1500 liters of combustion air per hour per liter of catalyst.

[0083] In another embodiment, steps a1) and a2) are carried out simultaneously. In this case, the impregnated support can be dried during step b). Step b) Drying of the impregnated surface

[0084] Step b) of drying the catalyst precursor obtained at the end of step a) is carried out at a temperature below 250°C, preferably between 15 and 180°C, more preferably between 30 and 160°C, even more preferably between 50 and 150°C, and even more preferably between 70 and 140°C, typically for a period of between 10 minutes and 24 hours. Longer periods are not excluded, but do not necessarily bring about improvement.

[0085] 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 atmosphere containing oxygen or under a mixture of inert gas and oxygen. It is advantageously carried out at atmospheric pressure or at reduced pressure. Preferably, this step is carried out at atmospheric pressure and in the presence of air or nitrogen.

[0086] Heat treatment of the dried catalyst (optional)

[0087] Optionally, after drying (step b), the catalyst is calcined under air, preferably combustion air, and more preferably methane combustion air, comprising between 40 and 80 grams of water per kg of air, an oxygen content of between 5% and 15% by volume, and a CO2 content of between 4% and 10% by volume. The calcination temperature is generally between 250°C and 900°C, preferably between approximately 300°C and approximately 500°C. The calcination time is generally between 0.5 hours and 5 hours. The volumetric flow rate per hour (VVH) is generally between 150 and 3000, preferably between 300 and 1500 liters of combustion air per hour per liter of catalyst. Reduction by a reducing gas (optional)

[0088] Optionally, the catalyst is reduced. This step is preferably carried out in the presence of a reducing gas, either in-situ, i.e., in the reactor where the catalytic transformation takes place, or ex-situ. Preferably, this step is carried out at a temperature between 100°C and 600°C, and even more preferably between 120°C and 500°C.

[0089] The reduction is carried out in the presence of a reducing gas comprising between 25 vol% and 100 vol% of hydrogen, preferably 100 vol% hydrogen. The hydrogen is optionally supplemented by an inert gas for the reduction, preferably argon, nitrogen, or methane.

[0090] The reduction generally includes a temperature rise phase followed by a plateau.

[0091] The duration of the reduction step is generally between 1 hour and 10 hours, preferably between 2 hours and 8 hours.

[0092] The Volumetric Hourly Velocity (VHV) is generally between 150 and 3000, preferably between 300 and 1500 litres of reducing gas per hour per litre of catalyst. Selective hydrogenation process

[0093] The present invention relates to a selective hydrogenation process for polyunsaturated compounds containing at least 2 carbon atoms per molecule, such as diolefins and / or acetylenic and / or alkenylaromatic compounds, also called styrenics, contained in a hydrocarbon feedstock having a final boiling point of 300°C or less, which process being carried out at a temperature between 0 and 300°C, at a pressure between 0.1 MPa and 10 MPa, at a molar ratio of hydrogen to (polyunsaturated compounds to be hydrogenated) between 0.1 and 10 and at a volumetric flow rate between 0.1 and 200 h⁻¹ when the process is carried out in the liquid phase, or at a molar ratio of hydrogen to (polyunsaturated compounds to be hydrogenated) between 0.5 and 1000 and at a volumetric flow rate between 100 and 40,000 h⁻¹ when the process is carried out in the gas phase, in presence of the catalyst described above or prepared by the process described above.

[0094] Monounsaturated organic compounds, such as ethylene and propylene, are the basis for the manufacture of polymers, plastics, and other value-added chemicals. These compounds are obtained from natural gas, naphtha, or diesel fuel that has been treated by steam cracking or catalytic cracking processes. These processes are carried out at high temperatures and produce, in addition to the desired monounsaturated compounds, 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 whose boiling point corresponds to the C5+ fraction (hydrocarbon compounds having at least 5 carbon atoms), in particular diolefinic, styrenic, or indenic compounds.These polyunsaturated compounds are highly reactive and lead to unwanted reactions in the polymerization units. It is therefore necessary to remove them before processing these fragments.

[0095] Selective hydrogenation is the main treatment developed to specifically remove undesirable polyunsaturated compounds from these hydrocarbon feedstocks. It allows the conversion of polyunsaturated compounds to the corresponding alkenes or aromatics while avoiding their complete saturation and thus the formation of the corresponding alkanes or naphthenes. In the case of steam cracking gasoline used as feedstock, selective hydrogenation also allows the selective hydrogenation of alkenyl aromatics into aromatics while avoiding the hydrogenation of the aromatic rings.

[0096] The hydrocarbon feedstock treated in the selective hydrogenation process has a final boiling point of 300°C or less and contains at least 2 carbon atoms per molecule and comprises at least one polyunsaturated compound. "Polyunsaturated compounds" are defined as compounds having at least one acetylenic group and / or at least one dienic group and / or at least one alkenyl-romatic group.

[0097] More specifically, the charge used is a steam cracking essence still called pyrolysis essence or C5+ cut.

[0098] The steam cracking gasoline or pyrolysis gasoline, advantageously used for carrying out the selective hydrogenation process according to the invention, corresponds to a hydrocarbon fraction whose boiling point is generally between 0 and 300°C, preferably between 10 and 250°C. The polyunsaturated hydrocarbons to be hydrogenated present in said steam cracking gasoline are in particular diolefinic compounds (butadiene, isoprene, cyclopentadiene, etc.), styrenic compounds (styrene, alpha-methylstyrene, etc.) and indenic compounds (indene, etc.). The steam cracking gasoline generally comprises the C5-C12 fraction with traces of C3, C4, C13, C14, and C15 (for example, between 0.1 and 3 wt% for each of these fractions).For example, a charge formed from pyrolysis gasoline generally has the following composition: 5 to 30% by weight of saturated compounds (paraffins and naphthenes), 40 to 80% by weight of aromatic compounds, 5 to 20% by weight of mono-olefins, 5 to 40% by weight of diolefins, 1 to 20% by weight of alkenyl-aromatic compounds, all compounds together forming 100%. It also contains 0 to 1000 ppm by weight of sulfur, preferably 0 to 500 ppm by weight of sulfur.

[0099] The technological implementation of the selective hydrogenation process is, for example, carried out by injecting, in an upward or downward flow, the polyunsaturated hydrocarbon feedstock and hydrogen into at least one fixed-bed reactor. This reactor may be isothermal or adiabatic. An adiabatic reactor is preferred. The polyunsaturated hydrocarbon feedstock may advantageously be diluted by one or more reinjections of the effluent from said reactor, where the selective hydrogenation reaction takes place, at various points in the reactor located between the inlet and outlet, in order to limit the temperature gradient within the reactor. The technological implementation of the selective hydrogenation process according to the invention may also advantageously be carried out by installing at least one of said supported catalysts in a reactive distillation column, in heat exchanger reactors, or in a slurry reactor.The hydrogen flow can be introduced at the same time as the feed to be hydrogenated and / or at one or more different points in the reactor.

[0100] In an embodiment according to the invention, when a selective hydrogenation process is carried out in which the feedstock is a steam cracking gasoline comprising polyunsaturated compounds, the molar ratio (hydrogen) / (polyunsaturated compounds to be hydrogenated) is generally between 0.5 and 10, preferably between 0.7 and 5.0 and even more preferably between 1.0 and 2.0, the temperature is between 0 and 200°C, preferably between 20 and 200°C and even more preferably between 30 and 180°C, the volumetric velocity per hour (VVH) is generally between 0.5 and 100 h⁻¹, preferably between 1 and 50 h⁻¹, and the pressure is generally... raral between 0.3 MPa and 8.0 MPa, preferably between 1.0 MPa and 7.0 MPa and even more preferably between 1.5 MPa and 4.0 MPa.

[0101] More preferably, a selective hydrogenation process is carried out in which the feedstock is a steam cracking gasoline comprising polyunsaturated compounds, the molar ratio hydrogen / (polyunsaturated compounds to be hydrogenated) is between 0.7 and 5.0, the temperature is between 20 and 200 °C, the hourly volumetric velocity (VVH) is generally between 1 and 50 h 1 and the pressure is between 1.0 and 7.0 MPa.

[0102] Even more preferably, a selective hydrogenation process is carried out in which the feedstock is a steam cracking gasoline comprising polyunsaturated compounds, the molar ratio hydrogen / (polyunsaturated compounds to be hydrogenated) is between 1.0 and 2.0, the temperature is between 30 and 180°C, the hourly volumetric velocity (VVH) is generally between 1 and 50 h 1 and the pressure is between 1.5 and 4.0 MPa.

[0103] The hydrogen flow rate is adjusted to ensure sufficient quantity is available to theoretically hydrogenate all polyunsaturated compounds and to maintain an excess of hydrogen at the reactor outlet.

[0104] The invention will now be illustrated by means of the following examples, which are in no way limiting. Examples

[0105] Example 1: preparation of a 10% Cu / AhOA catalyst (non-compliant)

[0106] 4.1 g of hydrated copper nitrate (Cu(NO3)2; 2.5 H2O, M=232.6 g / mol, 1.75 mmol) are dissolved in 10 mL of deionized water at room temperature. The solution is then added dropwise to 10 g of commercial Puralox TH100 alumina powder (Sasol, 80 µm diameter) in a 100 mL beaker. The mixture is then stirred until the solution is completely absorbed. The material is dried for 12 hours in air at 60°C and then calcined for 2 hours at 400°C under a stream of air. The material is reduced under hydrogen at 450°C for 2 hours.

[0107] Catalyst A comprises a copper element content of 10% by weight relative to the weight of the catalyst.

[0108] Example 2: preparation of a catalyst 6.1% In / AhCM non-conforming)

[0109] 2.2 g of hydrated indium nitrate (In(NO3)3; 5 H2O, M=391 g / mol, 0.57 mmol) are dissolved in 10 mL of deionized water at room temperature. The solution is then added dropwise to 10 g of commercial Puralox TH 100 alumina powder (Sasol, 80 µm diameter) in a 100 mL beaker. The mixture is then stirred until the solution is completely absorbed. The material is dried for 12 hours in air at 60°C and then calcined for 2 hours at 400°C under a stream of air. The material is reduced under hydrogen at 450°C for 2 hours.

[0110] Catalyst B comprises an indium element content of 6.1% by weight relative to the weight of the catalyst. [YES] Example 3: Preparation of a catalyst (9.4% Cu 5.6% In / AUCM ratio mol / mol Cu / In = 3.1, compliant) by co-impregnation

[0112] 2.2 g of hydrated indium nitrate (In(NO3)3;5 H2O, M=391 g / mol, 0.57 mmol) and 4.1 g of hydrated copper nitrate (Cu(NO3)2; 2.5 H2O, M=232.6 g / mol, 1.75 mmol) are dissolved in 10 mL of deionized water at room temperature. The solution is then added dropwise to 10 g of commercial Puralox TH 100 alumina powder (Sasol, 80 µm diameter) in a 100 mL beaker. The mixture is then stirred until the solution is completely absorbed. The material is dried for 12 h in air at 60°C and then calcined for 2 h at 400°C under a stream of air. The material is reduced under hydrogen at 450°C for 2 h.

[0113] Catalyst C comprises a copper content of 9.4% by weight relative to the catalyst weight and an indium content of 5.6% by weight relative to the catalyst weight. The Cu / In molar ratio is 3.1 mol / mol. Copper and indium alloy peaks are noted in XRD.

[0114] Example 4: preparation of a 9.4%Cu 5.6% In / Al2Q3 catalyst (mol / mol Cu / In ratio = 3.1, compliant) by successive impregnation.

[0115] 4.1 g of hydrated copper nitrate (Cu(NO3)2; 2.5 H2O, M=232.6 g / mol, 1.75 mmol) are dissolved in 10 mL of deionized water at room temperature. The solution is then added dropwise to 10 g of commercial Puralox TH100 alumina powder (Sasol, 80 µm diameter) in a 100 mL beaker. The mixture is then stirred until the solution is completely absorbed. The material is dried for 12 hours in air at 60°C.

[0116] 2.2 g of hydrated indium nitrate (In(NO3)3; 5 H2O, M=391 g / mol, 0.57 mmol) are Dissolved in 10 mL of deionized water at room temperature, the solution is then added dropwise to the dried material in a 100 mL beaker. The mixture is stirred until the solution is completely absorbed. The material is dried for 12 hours in air at 60°C and then calcined for 2 hours at 400°C under a stream of air. The material is then reduced under hydrogen at 450°C for 2 hours.

[0117] Catalyst D comprises a copper content of 9.4 wt% relative to the catalyst weight and an indium content of 5.6 wt% relative to the catalyst weight. The Cu / In molar ratio is 3.1 mol / mol. Copper and indium alloy peaks are noted in XRD.

[0118] Example 5: Preparation of a 9.7% Cu 3.5% In / AUCM catalyst (mol / mol Cu / In ratio = 5. compliant) by co-impregnation

[0119] 1.36 g of hydrated indium nitrate (In(NO3)3; 5 H2O, M=391 g / mol, 0.35 mmol) and 4.1 g of hydrated copper nitrate (Cu(NO3)2; 2.5 H2O, M=232.6 g / mol, 1.75 mmol) are dissolved in 10 mL of deionized water at room temperature. The solution is then added dropwise to 10 g of commercial Puralox TH100 alumina powder (Sasol, 80 µm diameter) in a 100 mL beaker. The mixture is then stirred until the solution is completely absorbed. The material is dried for 12 h in air at 60°C and then calcined for 2 h at 400°C under a stream of air. The material is reduced under hydrogen at 450°C for 2 h.

[0120] Catalyst E comprises a copper content of 9.7% by weight relative to the catalyst weight and an indium content of 3.5% by weight relative to the catalyst weight. The Cu / In molar ratio is 5 mol / mol. Copper and indium alloy peaks are noted in XRD.

[0121] Example 6: Preparation of a 9.7% Cu 2.5% In / Ah catalyst (mol / mol Cu / In ratio = 33. compliant) by co-impregnation

[0122] 0.97 g of hydrated indium nitrate (In(NO3)3;5 H2O, M=391 g / mol, 0.25 mmol) and 4.1 g of hydrated copper nitrate (Cu(NO3)2; 2.5 H2O, M=232.6 g / mol, 1.75 mmol) are dissolved in 10 mL of deionized water at room temperature. The solution is then added dropwise to 10 g of commercial Puralox TH100 alumina powder (Sasol, 80 µm diameter) in a 100 mL beaker. The mixture is then stirred until the solution is completely absorbed. The material is dried for 12 h in air at 60°C and then calcined for 2 h at 400°C under a stream of air. The material is reduced under hydrogen at 450°C for 2 h.

[0123] Catalyst F comprises a copper content of 9.7% by weight relative to the catalyst weight and an indium content of 2.5% by weight relative to the catalyst weight. The Cu / In molar ratio is 7 mol / mol. Copper and indium alloy peaks are noted in XRD.

[0124] Example 7: preparation of a catalyst 9.7% Cu 2.5% Ga / ALO^ fmol / mol Cu / In ratio= 7.1. compliant) by co-impregnation

[0125] 1.027 g of hydrated gallium nitrate (Ga(NO3)3; 9 H2O, M=418 g / mol, 0.25 mmol) 4.1 g of hydrated copper nitrate (Cu(NO3)2; 2.5 H2O, M=232.6 g / mol, 1.75 mmol) are dissolved in 10 mL of deionized water at room temperature. The solution is then added dropwise to 10 g of commercial Puralox TH100 alumina powder (Sasol, 80 µm diameter) in a 100 mL beaker. The mixture is then stirred until the solution is completely absorbed. The material is dried for 12 h in air at 60°C and then calcined for 2 h at 400°C under a stream of air. The material is reduced under hydrogen at 450°C for 2 h.

[0126] Catalyst G comprises a copper content of 9.7% by weight relative to the catalyst's weight and a gallium content of 1.5% by weight relative to the catalyst's weight. The Cu / In molar ratio is 7 mol / mol.

[0127] Example 8: Catalytic tests (performance in selective hydrogenation of butadiene)

[0128] The catalysts A to G described in the examples above are tested for the selective hydrogenation reaction of butadiene in the gas phase.

[0129] The composition of the charge to be selectively hydrogenated is as follows: 0.3% butadiene, 30% propene and 20% hydrogen in helium.

[0130] The selective hydrogenation reaction is carried out in a Pyrex plug flow reactor (internal diameter of 4mm) operating at atmospheric pressure and temperatures between 5°C and 200°C.

[0131] Prior to its introduction into the reactor, 50 mg of calcined powder catalyst (fraction 125 - 250 qm) are mixed with 200 mg of powdered silicon carbide of the same particle size.

[0132] The catalyst is activated in situ under a flow of pure hydrogen at 2 L / h / g of catalyst, at 450 °C for 2 hours (temperature ramp of 3 °C / min). The reactor is cooled to 90 °C under a flow of hydrogen, and then the reaction mixture is introduced.

[0133] Depending on the catalyst activity, the reactor temperature or the feed rate is adjusted to achieve 99% butadiene conversion. The reaction products are analyzed online over time by gas chromatography.

[0134] The conversion of butadiene is calculated according to the following formula:

[0135] Conversion (%) = 100*[l- (butadiene out / butadiene in)]

[0136] The butadiene activity normalized by copper content is expressed in moles of butadiene converted per second per mole of copper. The catalytic activities are measured at 90°C for catalysts A to G. They are reported in Table 1 below.

[0137] Selectivity is represented by the selectivity in alkenes and the quantity of alkane formed:

[0138] Formation of alkane (ppm) = (propane exiting - propane entering) + butane

[0139] The selectivity of the catalysts is compared to 99% butadiene conversion.

[0140] [Tables 1] Catalyst Cu content (% wt) In content (% wt) or Ga Cu / In or Cu / Ga (mol / mol) Preparation method Initial A (103 mol butadiene / second / mol copper) at 90°C Alkanes formed (ppm wt) at 99% conversion Deactivation A (non-compliant) 10 0 - I 2.7 180 yes B (non-compliant) 0 6.1 - I 0 0 - C (compliant) 9.4 5.6 3.1 Cl 0.070 38 no D (compliant) 9.4 5.6 3.1 Is 0.15 35 no E (compliant) 9.7 3.5 5 Cl 0.73 40 no F (compliant) 9.7 2.5 7 Cl 1.35 90 no G (compliant) 9.7 1.5 7 CI 2.3 130 no

[0141] I: Impregnation, CI: Co-Impregnancy, IS: Successive Impregnation.

[0142] Table 1: Comparison of the performance of catalysts A to G in selective hydrogenation of a mixture containing butadiene.

[0143] The monometallic catalyst B (non-conforming) comprising only indium is inactive for the reaction.

[0144] The catalysts C to G, according to the invention, are active for the hydrogenation of the butadiene. The selectivity of the catalysts of the invention is improved compared to the non-conforming catalyst A. Indeed, the addition of indium makes it possible to reduce the quantity of alkene formed at iso-conversion of butadiene, from 180 ppm wt for catalyst A (non-conforming) to 35 and 38 ppm wt (catalysts C and D, conforming, Cu / In ratio = 3.1), 40 ppm wt (catalyst E, conforming, Cu / In ratio = 5) and 90 ppm wt (catalyst F, conforming, Cu / In ratio = 7).

[0145] Furthermore, adding an element from group IIIA, chosen from indium and gallium, to copper results in a stable catalyst. The deactivation over time of the catalytic activity of catalysts C to G is very low compared to catalyst A (Cu only, non-compliant).

Claims

Claims

1. 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 of less than or equal to 300°C, which process is carried out at a temperature of between 0 and 300°C, at a pressure of between 0.1 MPa and 10 MPa, at a hydrogen / (polyunsaturated compounds to be hydrogenated) molar ratio of between 0.1 and 10 and at an hourly volumetric flow rate of between 0.1 and 200 h 1 when the process is carried out in the liquid phase, or at a hydrogen / (polyunsaturated compounds to be hydrogenated) molar ratio of between 0.5 and 1000 and at an hourly volumetric flow rate of between 100 and 40000 h 1 when the process is carried out in the gas phase, in the presence of a catalyst comprising an active phase comprising copper and an element of the column IIIA, and an alumina support, the copper content being between 0,5% and 25% by weight of copper element relative to the total weight of the catalyst, the atomic ratio between copper and the element of column IIIA being between 1 and 50 mol / mol, said catalyst being in the form of a powder with a particle size between 20 pm and 500 pm.,

2. The method of claim 1, wherein the element of column III A is selected from indium or gallium.

3. A method according to any one of claims 1 to 2, wherein when the element IIIA is indium, the indium content is between 0.02% and 25% by weight of indium element relative to the total weight of the catalyst.

4. A process according to any one of claims 1 to 2, wherein when the element IIIA is gallium, the gallium content is between 0.5% and 25% by weight of gallium element relative to the total weight of the catalyst.

5. Process according to any one of the preceding claims, characterized in that the specific surface area of the catalyst used is between 80 and 200 m2 / g.

6. Process according to any one of the preceding claims in which said catalyst is obtained by a preparation process comprising the following steps: a) a catalyst precursor is formed by carrying out the following sequence: al) an alumina powder is brought into contact with a solution comprising at least one precursor of the active copper phase; a2) the alumina powder is brought into contact with at least one solution comprising at least one precursor of the active phase based on an element from column IIIA; steps al) and a2) being carried out separately, in any order, or simultaneously; b) the catalyst precursor obtained at the end of step a) is dried at a temperature below 250°C to obtain a dried catalyst precursor.

7. Method according to claim 6, wherein when steps a1) and a2) are carried out separately, an intermediate drying step is carried out between steps a1) and a2), or between steps a2) and a1), in which the catalyst precursor obtained at the end of step a1), or of step a2), is dried at a temperature below 250°C.

8. Method according to claim 7, in which the catalyst precursor obtained at the end of the intermediate drying step is subjected to a heat treatment at a temperature between 250°C and 1000°C.

9. A method according to claim 6, wherein steps a1) and a2) are carried out simultaneously.

10. A method according to any one of claims 6 to 9, wherein the precursor of the active copper phase is selected from copper acetate, copper acetylacetonate, copper nitrate, copper sulfate, copper chloride, copper bromide, copper iodide or copper fluoride.

11. A method according to any one of the preceding claims, wherein the element IIIA of the active phase is indium, and wherein the indium precursor is selected from indium acetate, indium acetylacetonate, indium nitrate, indium sulfate, indium sulfide, indium chloride, indium mercaptoacetate, indium bromide, indium iodide, indium fluoride, indium oxide, indium phosphide, indium hydroxide.

12. A method according to any one of claims 1 to 10, wherein the element IIIA of the active phase is gallium, and wherein the gallium precursor is selected from gallium acetylacetonate, gallium nitrate, gallium sulfate, gallium sulfide, gallium chloride, gallium bromide, gallium iodide, gallium oxide, gallium nitride, gallium phosphide, gallium perchlorate, organics such as gallium triethyl and gallium trimethyl.