Catalyst comprising copper and an element of column iiia

Abstract

The invention relates to 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 of the copper element relative to the total weight of the catalyst, the atomic ratio between the copper and the element of column IIIA being between 1 and 50 mol / mol, characterised in that the support is in the form of a bead or an extrudate comprising a specific surface area between 10 and 250 m2 / g.

Description

[0001] CATALYST COMPRISING COPPER AND AN ELEMENT FROM COLUMN IIIA

[0002] Technical field

[0003] The present invention relates to a supported metal catalyst whose active phase is based on copper and an element from column IIIA, chosen from indium and gallium, intended particularly for the hydrogenation of unsaturated hydrocarbons, and more particularly, for the selective hydrogenation of polyunsaturated compounds.

[0004] State of the art

[0005] Monounsaturated organic compounds, such as ethylene and propylene, are used in the manufacture of polymers, plastics and other value-added chemicals. These compounds are obtained from natural gas, naphtha or diesel oil that has been treated by steam cracking or catalytic cracking processes. These processes are operated 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 with 5 or more carbon atoms), in particular styrenic or indenic compounds.These polyunsaturated compounds are highly reactive and lead to parasitic reactions in the polymerization units. It is therefore necessary to eliminate them before recovering these cuts.

[0006] Selective hydrogenation is the main treatment developed to specifically remove unwanted 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 therefore the formation of the corresponding alkanes or naphthenes.

[0007] 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 metal particles deposited on a support. The metal content, the size of the metal particles, and the distribution of the active phase in the support are among the criteria that affect the activity and selectivity of the catalysts.

[0008] Palladium-based catalysts are widely used in selective hydrogenation reactions of C2-C4 light fractions. 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 at the periphery of the catalyst (egg-shell catalyst according to English terminology, for example described in FR2922784 or US2010 / 217052).

[0009] Recent years have seen an increase in the price of noble metals, particularly 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.

[0010] Thus, the publication by Wang et al. (Chem. Commun., 2021, 57, 7031-7034) describes the use of a catalyst comprising iron supported on titanium oxide for the selective hydrogenation of butadiene to alkenes at 175°C.

[0011] Patent application CN 110433813A discloses the use of a catalyst containing a Culn / ZrC>2 alloy for the hydrogenation of CO2 to methanol. The catalyst is prepared by coprecipitation of precursors of the three elements.

[0012] Patent application CN114054024A 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) chosen from Ni, In, Mo, W, Fe and Zn with a ratio of 0.2-1.5 based on the metal, on a SiC>2 support.

[0013] The publication by Onyestyàk et al. (Catalysis Communications, 2012, 26, 19-24) describes the use of a Culn catalyst on gamma AI2O3 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 equal to 203 m 2 / g.

[0014] The publication by Zhang et al. (Chinese Journal of Catalysis, 2018, 39, 99-108) describes the use of a Culn catalyst on SiC>2 for the hydrogenation of methyl acetate to ethanol. The addition of 0.2-2% indium is carried out on a catalyst comprising 30% Cu / SiCh corresponding to a Cu / ln molar ratio greater than 66 mol / mol.

[0015] The publication by Dong et al. (Applied Catalysis B: Environmental, 2018, 244) describes the use of a catalyst comprising 10% Cu on SBA15 type silica and indium such that the Cu / ln ratio is between 0.01 and 15 to hydrogenate acetic acid into ethanol.

[0016] Surprisingly, the Applicant has discovered that the use of a catalyst for the selective hydrogenation of polyunsaturated compounds comprising an active phase comprising copper and an element chosen from column III A, preferably chosen from indium and gallium, and an alumina support, in the form of beads or extrudates, and with a particular specific surface area allows a significant improvement in terms of selectivity, while retaining acceptable catalytic activity.

[0017] Objects of the invention

[0018] A first subject matter according to the invention relates to a catalyst comprising an active phase comprising copper and an element from column II IA, 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 the copper and the element from column IIIA being between 1 and 50 mol / mol, characterized in that said support is in the form of a ball or an extrudate comprising a specific surface area of ​​between 10 m 2 / g and 250 m 2 / g.

[0019] According to one or more embodiments according to the invention, the element of column III A is chosen from indium or gallium.

[0020] According to one or more embodiments according to the invention, 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.

[0021] According to one or more embodiments according to the invention, 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.

[0022] According to one or more embodiments of the invention, when element IIIA is indium, copper and indium are present in the form of an alloy.

[0023] According to one or more embodiments according to the invention, said support is an extrudate comprising three lobes or four lobes.

[0024] According to one or more embodiments according to the invention, the specific surface area of ​​said support is between 160 m 2 / g and 210 m 2 / g.

[0025] Another subject matter according to the invention relates to a method for preparing a catalyst according to the invention, comprising the following steps: a) an alumina gel is supplied; b) the alumina gel from step a) is shaped to form an alumina support; c) the following sequence is carried out to obtain a catalyst precursor: c1) the alumina support is brought into contact with a solution comprising at least one precursor of the active copper phase; c2) the alumina support is brought into contact with at least one solution comprising at least one precursor of the active phase based on an element from column 11 IA; steps c1) and c2) being carried out separately, in any order, or simultaneously; d) the catalyst precursor obtained at the end of step c) is dried at a temperature below 250°C to obtain a dried catalyst precursor.

[0026] According to one or more embodiments according to the invention, the shaped alumina gel obtained at the end of step b) is subjected to a heat treatment comprising at least one hydrothermal treatment step in an autoclave in the presence of an acid solution, at a temperature between 100°C and 800°C, then to at least one calcination step, at a temperature between 400°C and 1500°C, carried out after the hydrothermal treatment step, to obtain said alumina support.

[0027] According to one or more embodiments according to the invention, when steps c1) and c2) are carried out separately in any order, an intermediate drying step is carried out between steps c1) and c2), or between steps c2) and c1), in which the catalyst precursor obtained at the end of step c1), or of step c2), is dried at a temperature below 250°C.

[0028] According to one or more embodiments according to the invention, 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.

[0029] According to one or more embodiments according to the invention, steps c1) and c2) are carried out simultaneously.

[0030] 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. According to one or more embodiments of the invention, the element II IA of the active phase is indium, and the precursor of the active indium phase is 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.

[0031] According to one or more embodiments according to the invention, the element II IA of the active phase is gallium, and the precursor of the gallium active phase is chosen from 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.

[0032] Another subject matter 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 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 h- 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 h' 1 and 40,000 h' 1 when the process is carried out in the gas phase, in the presence of a catalyst according to the invention, or obtained by a preparation process according to the invention.

[0033] Detailed description of the invention

[0034] Definitions

[0035] 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 II IA according to the CAS classification corresponds to the metals of column 13 according to the new IUPAC classification.

[0036] BET specific surface area is measured by nitrogen physisorption. 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”, Academic Press, 1999.

[0037] 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®.

[0038] Copper, indium and gallium contents are measured by X-ray fluorescence.

[0039] Active phase of the catalyst

[0040] The catalyst according to the invention comprises an active phase comprising copper and an element from column IIIA, and an alumina support. The copper content is 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 from column IIIA is between 1 and 50 mol / mol. The catalyst is characterized in that the support is in the form of a ball or an extrudate comprising a specific surface area of ​​between 10 m 2 / g and 250 m 2 / g.

[0041] The copper content in the catalyst in the form of beads or extrudates 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, and even more preferably between 5 and 15% by weight.

[0042] The content of element from column III A in the catalyst is preferably between 0.02% and 25% by weight of element from column III A 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.

[0043] Preferably, the element of column IIIA is chosen from indium or gallium.

[0044] When the 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.

[0045] When the element IIIA is gallium, the gallium content is preferably between 0.5% and 25% by weight of gallium element 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.

[0046] The atomic ratio between copper and the element of column 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. When the atomic ratio between copper and the element of column III A is between 10 and 45 mol / mol, preferably between 15 and 45 mol / mol, and even more preferably between 18 and 40 mol / mol, the catalytic activity is improved in selective hydrogenation of polyunsaturated compounds in addition to the improvement of selectivity.

[0047] According to one or more embodiments, the copper is distributed homogeneously throughout the shaped support.

[0048] According to one or more embodiments, the element of column III A, preferably chosen from indium and gallium, is distributed homogeneously throughout the porous shaped support.

[0049] In one embodiment according to the invention, the catalyst may preferably contain the presence of an alloy containing copper and indium. In this embodiment, the average particle size of the metal crystallites comprising copper and indium is advantageously between 3.5 nm and 100 nm, preferably between 4 nm and 50 nm.

[0050] The specific surface area of ​​the catalyst is advantageously between 10 m 2 / g and 250 m 2 / g, preferably between 20 m 2 / g and 240 m 2 / g, more preferably between 40 m 2 / g and 230 m 2 / g, more preferably between 80 m 2 / g and 220 m 2 / g, and even more preferably between 160 m 2 / g and 210 m 2 / g.

[0051] The total pore volume (TPV) of the catalyst is advantageously between 0.1 cm 3 / g and 1.5 cm 3 / g, preferably between 0.2 cm3 / g and 1.4 cm 3 / g, and even more preferably between 0.25 cm 3 / g and 1.3 cm 3 / g.

[0052] The catalyst support according to the invention is alumina, that is to say that 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 alumina type, alone or as a mixture.

[0053] According to the invention, the alumina support may comprise impurities such as metal oxides of groups HA, 111 B, IVB, II B, 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.

[0054] The specific surface area of ​​the support is between 10 m 2 / g and 250 m 2 / g, preferably between 20 m 2 / g and 240 m 2 / g, more preferably between 40 m 2 / g and 230 m 2 / g, more preferably between 80 m 2 / g and 220 m 2 / g, and even more preferably between 160 m 2 / g and 210 m 2 / g.

[0055] The total pore volume (TPV) of the porous support is advantageously between 0.1 cm 3 / g and 1.5 cm 3 / g, preferably between 0.2 cm 3 / g and 1.4 cm 3 / g, and even more preferably between 0.25 cm 3 / g and 1.3 cm 3 / g.

[0056] The support is either in the form of balls or in the form of an extrudate, advantageously of trilobal or quadrilobal shape. When the support is in the form of balls, the diameter of the balls is generally between 1 mm and 10 mm, preferably between 2 mm and 8 mm, and even more preferably between 2 mm and 6 mm. When the support is in the form of a quadrilobal type extrudate, the length of the extrudate is generally between 2 mm and 10 mm, preferably between 2 mm and 8 mm, and more preferably between 3 mm and 6 mm. When the support is in the form of a quadrilobal type extrudate, the extrudates have a diameter generally between 0.5 mm and 10 mm, preferably between 0.8 mm and 3.2 mm and very preferably between 1.0 mm and 2.5 mm and a length of between 0.5 and 2.0 mm.

[0057] Catalyst preparation

[0058] According to the invention, the method for preparing the catalyst comprises the following steps: a) an alumina gel is supplied; b) the alumina gel from step a) is shaped to obtain an alumina support; c) the following sequence is carried out to obtain a catalyst precursor: c1) the alumina support is brought into contact with a solution comprising at least one precursor of the active copper phase; c2) the alumina support is brought into contact with at least one solution comprising at least one precursor of the active phase based on an element from column 11 IA; steps c1) and c2) being carried out separately, in any order, or simultaneously; d) the catalyst precursor obtained at the end of step c) is dried at a temperature below 250°C to obtain a dried catalyst precursor.

[0059] The different stages are explained in detail below.

[0060] Step a) - Alumina gel

[0061] The catalyst according to the invention comprises an alumina support which is obtained from an alumina gel (or alumina gel) which essentially comprises a precursor of the aluminum oxy(hydroxide) (AIO(OH)) type - also called boehmite.

[0062] According to the invention, the alumina gel (or otherwise called boehmite gel) is synthesized by precipitation of basic and / or acid solutions of aluminum salts induced by pH change or any other method known to those skilled in the art (P. Euzen, P. Raybaud, X. Krokidis, H. Toulhoat, JL Le Loarer, JP Jolivet, C. Froidefond, Alumina, in Handbook of Porous Solids, Eds F. Schûth, KSW Sing, J. Weitkamp, ​​Wiley-VCH, Weinheim, Germany, 2002, pp. 1591-1677).

[0063] Generally the precipitation reaction is carried out at a temperature between 5°C and 80°C and at a pH between 6 and 10. Preferably the temperature is between 35°C and 70°C and the pH is between 6 and 10.

[0064] According to one embodiment, the alumina gel is obtained by bringing an aqueous solution of an acidic aluminum salt into contact with a basic solution. For example, the acidic aluminum salt is chosen from the group consisting of aluminum sulfate, aluminum nitrate or aluminum chloride and preferably, said acidic salt is aluminum sulfate. The basic solution is preferably chosen from sodium hydroxide or potassium hydroxide. Alternatively, an alkaline solution of aluminum salts, which may be chosen from the group consisting of sodium aluminate and potassium aluminate, may be brought into contact with an acidic solution. In a highly preferred variant, the gel is obtained by bringing a sodium aluminate solution into contact with nitric acid. The sodium aluminate solution advantageously has a concentration of between 10 5 and 10' 1 mol.L' 1, and preferably this concentration is between 10' 4 and 10' 2 mol.L'

[0065] 1 According to another embodiment, the alumina gel is obtained by bringing an aqueous solution of acidic aluminum salts into contact with an alkaline solution of aluminum salts.

[0066] Step b) - Shaping the support

[0067] The support can advantageously be shaped by any technique known to those skilled in the art. The shaping can be carried out, for example, by kneading-extrusion, by the oil-drop method, by granulation on a rotating plate or by any other method well known to those skilled in the art. The catalysts according to the invention are manufactured and used in the form of extrudates or beads. The advantageous shaping method according to the invention is extrusion and the preferred extrudate shapes are the trilobal or quadrilobal shape.

[0068] In a particular embodiment when the support is an extrudate, the alumina gel obtained at the end of step a) is subjected to a mixing step, preferably in an acid medium. The acid used may be, for example, nitric acid. This step is carried out using known tools such as Z-arm mixers, grinding wheel mixers, continuous single or twin screws allowing the transformation of the gel into a product having the consistency of a paste. According to an advantageous embodiment, one or more compounds called "pore-forming agents" are introduced into the mixing medium. These compounds have the property of degrading upon heating and thus creating porosity in the support. For example, wood flour, charcoal, tars, plastics may be used as pore-forming compounds. The paste thus obtained after mixing is passed through an extrusion die.

[0069] After shaping, the support is optionally dried at a temperature greater than or equal to 50°C and less than 250°C for a period advantageously between 4 hours and 16 hours.

[0070] Optionally, the support obtained at the end of step b) then undergoes a hydrothermal treatment step which allows it to be given physical properties corresponding to the intended application. The term "hydrothermal treatment" refers to a treatment by passing through an autoclave in the presence of water at a temperature above ambient temperature. During this hydrothermal treatment, the shaped alumina can be treated in different ways. Thus, the alumina can be impregnated with an acid solution, prior to its passage through the autoclave, the hydrothermal treatment of the alumina being able to be carried out either in the vapor phase or in the liquid phase, this vapor or liquid phase of the autoclave being able to be acidic or not. This impregnation, before the hydrothermal treatment, can be carried out dry or by immersing the alumina in an acidic aqueous solution.Dry impregnation means bringing the alumina into contact with a volume of solution less than or equal to the total pore volume of the treated alumina. Preferably, the impregnation is carried out dry.

[0071] The extruded support can also be treated without prior impregnation with an acid solution, the acidity being provided in this case by the aqueous liquid of the autoclave. The acidic aqueous solution comprises at least one acid compound for dissolving at least part of the alumina in the extrudates. The term "acid compound for dissolving at least part of the alumina in the extrudates" means any acid compound which, when brought into contact with the alumina extrudates, dissolves at least part of the aluminum ions. The acid must preferably dissolve at least 0.5% by weight of alumina in the alumina extrudates.

[0072] Preferably, this acid is chosen from strong acids such as nitric acid, hydrochloric acid, perchloric acid, sulfuric acid or a weak acid used at a concentration such that its aqueous solution has a pH of less than 4, such as acetic acid, or a mixture of these acids.

[0073] According to a preferred embodiment, the hydrothermal treatment is carried out in the presence of nitric acid and acetic acid taken alone or as a mixture. The autoclave is preferably a rotating basket autoclave such as that defined in patent application EP-A-0 387 109.

[0074] Hydrothermal treatment can also be carried out under saturated steam pressure or under a partial pressure of water vapor at least equal to 70% of the saturated steam pressure corresponding to the treatment temperature.

[0075] Preferably the hydrothermal treatment is carried out at a temperature between 100 and 800°C, preferably between 200 and 700°C, preferably between 30 minutes and 8 hours, more preferably between 30 minutes and 3 hours.

[0076] Optionally, the dried support is calcined at a temperature between 250°C and 1000°C, in the presence or absence of an air flow containing up to 150 of water per kilogram of dry air for a duration advantageously between 3 hours and 8 hours.

[0077] At the end of step b), the alumina support obtained has the specific textural properties as described above.

[0078] Step c) - Bringing the support into contact with a precursor of the active copper phase

[0079] Step c) for obtaining a catalyst precursor is characterized by the following sequence: c1) the alumina support is brought into contact with a solution comprising at least one precursor of the active copper phase; c2) the alumina support is brought into contact with at least one solution comprising at least one precursor of the active phase based on an element from column 11 IA; steps c1) and c2) being carried out separately, in any order, or simultaneously.

[0080] Said step c1) is characterized in that the contacting of the support with a solution containing a precursor of the active copper phase can be carried out by impregnation, 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 possible addition of an acid or a base.

[0081] Said step c1) is preferably carried out by impregnation of the support consisting for example of bringing the support into contact with at least one aqueous solution containing a copper precursor.

[0082] Preferably, said step c1) is carried out by dry impregnation, which consists of bringing the support into contact with at least one solution, containing, preferably consisting of, at least one copper precursor, the volume of the solution of which is between 0.25 and 1.5 times the pore volume of the support to be impregnated.

[0083] The copper precursor salt is preferably selected from copper acetate, copper acetylacetonate, copper nitrate, copper sulfate, copper chloride, copper bromide, copper iodide or copper fluoride.

[0084] Preferably, the copper precursor salt is selected from copper nitrate, copper sulfate or copper chloride.

[0085] The concentration of copper in solution is adjusted according to the type of impregnation (dry or excess impregnation) and the pore volume of the support so as to obtain for the supported catalyst, a copper content of 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.

[0086] Said step c2) is characterized in that bringing the support into contact with a solution containing a precursor of at least one precursor of an element from column III A, preferably chosen from indium and gallium, in accordance with the implementation of step c2), can be carried out by impregnation, dry or in excess, or by deposition-precipitation, according to methods well known to those skilled in the art.

[0087] Said step c2) is preferably carried out by impregnation of the shaped support, consisting for example of bringing the support into contact 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 possible addition of an acid or a base.

[0088] Preferably, said step c2) is carried out by dry impregnation, which consists of bringing the support into contact with at least one solution, containing, preferably consisting of, at least one precursor of an element from column III A, preferably chosen from indium and gallium, the volume of the solution of which is between 0.25 and 1.5 times the pore volume of the support to be impregnated.

[0089] The indium precursor is preferably 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.

[0090] 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.

[0091] The concentration in solution of the element of column III A, preferably chosen from indium and gallium, is adjusted according to the type of impregnation (dry or excess impregnation) and the pore volume of the support so as to obtain for the supported catalyst, a content of element of column III A, preferably chosen from indium and gallium of between 0.02% and 25% by weight of element of column III A, preferably chosen from indium and gallium relative to the total weight of the catalyst, preferably between 0.05 and 20% by weight, more preferably between 0.1 and 15% by weight.

[0092] Likewise, the concentration of element from column III A, preferably chosen from indium and gallium in solution, is supplied in such a way that the atomic ratio between copper and element from column III A, preferably chosen from indium and gallium, 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.

[0093] When steps c1) and c2) are carried out separately, an intermediate drying step is carried out between steps c1) and c2), or between steps c2) and c1), in which the catalyst precursor obtained at the end of step c1), or step c2), 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 times are not excluded, but do not necessarily provide an improvement.

[0094] 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 of between 5% and 25% by volume and a carbon dioxide level of between 0% and 10% by volume.

[0095] Optionally, the catalyst precursor obtained at the end of the intermediate drying step is subjected to a heat treatment in air, preferably combustion air, and more preferably methane combustion air, comprising between 40 and 80 grams of water per kg of air, an oxygen level of between 5% and 15% by volume and a CO2 level 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 hourly volumetric velocity (HVV) is generally between 150 and 3000, preferably between 300 and 1500 liters of combustion air per hour and per liter of catalyst.

[0096] In another embodiment, steps c1) and c2) are carried out simultaneously. In this case, the impregnated support can be dried during step d).

[0097] Step d) of drying the catalyst precursor obtained at the end of step c) 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 provide an improvement.

[0098] The drying step may 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.

[0099] Heat treatment of dried catalyst (optional)

[0100] Optionally, after drying (step d), the catalyst is calcined in air, preferably combustion air, and more preferably methane combustion air, comprising between 40 and 80 grams of water per kg of air, an oxygen level of between 5% and 15% by volume and a CO2 level 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 hourly volumetric velocity (HVV) is generally between 150 and 3000, preferably between 300 and 1500 liters of combustion air per hour and per liter of catalyst.

[0101] Reduction by a reducing qaz (optional)

[0102] 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 is carried out, or ex situ. Preferably, this step is carried out at a temperature between 100°C and 600°C, even more preferably between 120°C and 500°C.

[0103] The reduction is carried out in the presence of a reducing gas comprising between 25 vol% and 100 vol% hydrogen, preferably 100% hydrogen by volume. The hydrogen is optionally supplemented by an inert gas for reduction, preferably argon, nitrogen or methane.

[0104] The reduction generally includes a temperature increase phase followed by a plateau.

[0105] The duration of the reduction stage is generally between 1 hour and 10 hours, preferably between 2 hours and 8 hours.

[0106] The Hourly Volumetric Velocity (HVV) is generally between 150 and 3000, preferably between 300 and 1500 liters of reducing gas per hour and per liter of catalyst.

[0107] Selective hydrogenation process

[0108] The present invention also relates to a process for the selective hydrogenation of polyunsaturated compounds containing at least 2 carbon atoms per molecule, such as diolefins and / or acetylenics and / or alkenylaromatics, also called styrenics, 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 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 -1when 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 40,000 h -1 when the process is carried out in the gas phase, in the presence of the catalyst according to the invention or prepared by the process according to the invention described above.

[0109] 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 oil that has been treated by steam cracking or catalytic cracking processes. These processes are operated 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 with at least 5 carbon atoms), in particular diolefinic or styrenic or indenic compounds. These polyunsaturated compounds are very reactive and lead to parasitic reactions in the polymerization units.It is therefore necessary to eliminate them before using these cuts.

[0110] Selective hydrogenation is the main treatment developed to specifically remove unwanted 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 therefore the formation of the corresponding alkanes or naphthenes. In the case of steam cracked gasolines used as feedstock, selective hydrogenation also allows the selective hydrogenation of alkenyl aromatics to aromatics while avoiding the hydrogenation of aromatic nuclei.

[0111] 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. "Polyunsaturated compounds" means compounds comprising at least one acetylenic function and / or at least one diene function and / or at least one alkenyl aromatic function.

[0112] More specifically, the charge used is a steam cracking gasoline also called pyrolysis gasoline or C5+ cut.

[0113] The steam cracking gasoline or pyrolysis gasoline, advantageously used for implementing 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 indene compounds (indene, etc.). The steam cracking gasoline generally comprises the C5-C12 fraction with traces of C3, C4, C13, C14, C15 (for example between 0.1 and 3% by weight 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 monoolefins, 5 to 40% by weight of diolefins, 1 to 20% by weight of alkenyl aromatic compounds, all of the compounds forming 100%. It also contains from 0 to 1000 ppm by weight of sulfur, preferably from 0 to 500 ppm by weight of sulfur.

[0114] The technological implementation of the selective hydrogenation process is for example carried out by injecting, in ascending or descending flow, the polyunsaturated hydrocarbon feedstock and hydrogen into at least one fixed-bed reactor. Said reactor may be of the isothermal type or of the adiabatic type. 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 occurs, at various points of the reactor, located between the inlet and the outlet of the reactor in order to limit the temperature gradient in the reactor. The technological implementation of the selective hydrogenation process according to the invention may also be advantageously carried out by the installation of at least said supported catalyst in a reactive distillation column or in exchanger reactors or in a slurry-type reactor.The hydrogen flow can be introduced at the same time as the feedstock to be hydrogenated and / or at one or more different points in the reactor.

[0115] 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 hourly volumetric velocity (HVV) is generally between 0.5 and 100 h' 1 , preferably between 1 and 50 h' 1and the pressure is generally 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. More preferably, a selective hydrogenation process is carried out in which the feedstock is a steam cracking gasoline comprising polyunsaturated compounds, the hydrogen / (polyunsaturated compounds to be hydrogenated) molar ratio is between 0.7 and 5.0, the temperature is between 20 and 200 °C, the hourly volumetric velocity (HVV) is generally between 1 and 50 h -1 and the pressure is between 1.0 MPa and 7.0 MPa.

[0116] Even more preferably, a selective hydrogenation process is carried out in which the feedstock is a steam cracking gasoline comprising polyunsaturated compounds, the hydrogen / (polyunsaturated compounds to be hydrogenated) molar ratio is between 1.0 and 2.0, the temperature is between 30 and 180°C, the hourly volumetric velocity (HVV) is generally between 1 and 50 h' 1 and the pressure is between 1.5 MPa and 4.0 MPa.

[0117] The hydrogen flow rate is adjusted to provide sufficient quantity to theoretically hydrogenate all the polyunsaturated compounds and to maintain an excess of hydrogen at the reactor outlet.

[0118] Examples

[0119] The invention will now be illustrated by the following examples which are in no way limiting.

[0120] Example 1: Preparation of AL-1 alumina extrudates

[0121] An alumina gel is synthesized using a mixture of sodium aluminate and aluminum sulfate. The precipitation reaction is carried out at a temperature of 60°C, at a pH of 9, for 60 minutes and with stirring at 200 rpm.

[0122] The gel thus obtained is mixed on a Z-arm mixer to produce the paste. Extrusion is carried out by passing the paste through a die equipped with 1.6 mm diameter trilobe-shaped orifices. The extrudates thus obtained are dried at 150°C for 12 hours and then calcined at 450°C under a flow of dry air for 5 hours. The dry air used in this example and in all the examples below contains less than 5 grams of water per kilogram of air.

[0123] The AL-1 alumina support has a specific surface area of ​​200 m 2 / g, a pore volume (determined by mercury porosimetry) of 0.85 mL / g and a median mesoporous diameter of 15 nm. The sodium content is 0.0350 wt% and the sulfur content is 0.15 wt% relative to the total weight of the support. Example 2: Preparation of AL-2 alumina extrudates

[0124] An alumina gel is synthesized via a mixture of sodium aluminate and aluminum sulfate. The precipitation reaction is carried out at a temperature of 50°C, at a pH of 8.7, for 60 minutes and with stirring at 200 rpm.

[0125] The gel thus obtained is mixed on a Z-arm mixer to produce the paste. Extrusion is carried out by passing the paste through a die equipped with 1.6 mm diameter trilobe-shaped orifices. The extrudates thus obtained are dried at 150°C for 12 hours and then calcined at 450°C under a flow of dry air for 5 hours. The dry air used in this example and in all the examples below contains less than 5 grams of water per kilogram of air.

[0126] The AL-2 alumina support has a specific surface area of ​​300 m 2 / g, a pore volume (determined by mercury porosimetry) of 0.65 mL / g and a median mesoporous diameter of 8 nm. The sodium content is 0.0550 wt% and the sulfur content is 0.20 wt% relative to the total weight of the support.

[0127] Example 3: preparation of a 10% Cu / AL-1 catalyst (non-compliant)

[0128] 12.2 g of hydrated copper nitrate (Cu(NOa)2; 2.5 H2O, M= 232.56 g / mol, 5.24 mmol) are dissolved in 21 mL of deionized water at room temperature. The solution is then added dropwise to 30 g of shaped support AL-1 in a rotating drageoir at room temperature. The material is dried for 16 hours in air at 120°C and then calcined for 2 hours at 400°C under air flow.

[0129] Catalyst A comprises a copper element content of 10% by weight relative to the total weight of the catalyst.

[0130] 6.7 g of hydrated indium nitrate (ln(NOa)3; 5 H2O, M=391 g / mol, 1.71 mmol) are dissolved in 21 mL of deionized water at room temperature. The solution is then added dropwise to 30 g of shaped support AL-1 in a rotating dragee at room temperature. The material is dried for 12 hours in air at 60°C and then calcined for 2 hours at 400°C under air flow.

[0131] Catalyst B comprises an indium element content of 6.1% by weight relative to the total weight of the catalyst. Example 5: preparation of a 9.2% wt. Cu 7.6% wt. ln / AL-1 catalyst (mol / mol ratio Cu / ln = 2.2, compliant) by co-impregnation

[0132] 9.3 g of hydrated indium nitrate (ln(NOa)3; 5 H2O, M=391 g / mol, 2.37 mmol) and 12.2 g of hydrated copper nitrate (Cu(NOa)2; 2.5 H2O, M=232.6 g / mol, 5.24 mmol) are dissolved in 21 mL of deionized water at room temperature. The solution is then added dropwise to 30 g of shaped support AL-1 in a rotating dragee at room temperature. The material is dried for 16 h in air at 120°C and then calcined for 2 h at 400°C under air flow.

[0133] Catalyst C comprises a copper element content of 9.2% by weight relative to the total weight of the catalyst and an indium content of 7.6% by weight relative to the total weight of the catalyst. The Cu / ln molar ratio is 2.2 mol / mol. mol / mol Cu / ln= 33

[0134] 0.6 g of hydrated indium nitrate (ln(NOa)3 ;5 H2O, M=391 g / mol, 0.15 mmol) and 12.2 g of hydrated copper nitrate (Cu(NOs)2 ; 2.5 H2O, M=232.6 g / mol, 5.24 mmol) are dissolved in 21 mL of deionized water at room temperature. The solution is then added dropwise to 30 g of shaped support AL-1 in a rotating dragee at room temperature. The material is dried for 16 h in air at 120°C and then calcined for 2 h at 400°C under air flow.

[0135] Catalyst D comprises a copper element content of 9.9% by weight relative to the total weight of the catalyst and an indium content of 0.5% by weight relative to the total weight of the catalyst. The Cu / In molar ratio is 33 mol / mol. 9.9%Cu 0.5% ln / AL-2 (mol / mol Cu / ln ratio= 33 no co-i

[0136] 0.6 g of hydrated indium nitrate (ln(NOs)3 ;5 H2O, M=391 g / mol, 0.15 mmol) and 12.2 g of hydrated copper nitrate (Cu(NOs)2 ; 2.5 H2O, M=232.6 g / mol, 5.24 mmol) are dissolved in 21 mL of deionized water at room temperature. The solution is then added dropwise to 30 g of shaped support AL-2 in a rotating dragee at room temperature. The material is dried for 16 hours in air at 120°C and then calcined for 2 hours at 400°C under air flow. Catalyst E comprises a copper element content of 9.9% by weight relative to the total weight of the catalyst and an indium content of 0.5% by weight relative to the total weight of the catalyst. The Cu / ln molar ratio is 33 mol / mol.

[0137] Example 8: Catalytic tests: performance in selective hydrogenation of a mixture containing isoprene

[0138] Catalysts A to E described in the examples above are tested for the selective hydrogenation reaction of isoprene.

[0139] The composition of the feedstock to be selectively hydrogenated is as follows: 10% by weight isoprene (supplier Sigma Aldrich®, purity 99%), 90% by weight n-heptane (solvent) (supplier VWR®, purity > 99% chromanorm HPLC). This composition corresponds to the initial composition of the reaction mixture.

[0140] The selective hydrogenation reaction is carried out in a 500 mL stainless steel autoclave, equipped with magnetically driven mechanical stirring and capable of operating under a maximum pressure of 100 bar (10 MPa) and temperatures between 5°C and 200°C.

[0141] Prior to its introduction into the autoclave, a quantity of 4 mL of catalyst (between 2.5 and 3 g) is reduced ex situ under a hydrogen flow of 1 L / h / g of catalyst, at 450 °C for 2 hours (temperature rise ramp of 1 °C / min), then it is transferred into the autoclave, protected from air. After adding 225 mL of n-heptane (153 g), the autoclave is closed, purged, then pressurized under 35 bar (3.5 MPa) of hydrogen, and brought to the test temperature equal to 90 °C. At time t = 0, approximately 18 g of isoprene are introduced into the autoclave. The reaction mixture then has the composition described above and stirring is started at 1600 rpm. The pressure is maintained constant at 35 bar (3.5 MPa) in the autoclave using a reservoir bottle located upstream of the reactor.

[0142] The progress of the reaction is monitored by taking samples of the reaction medium at regular time intervals: the isoprene is hydrogenated to methyl-butenes. If the reaction is prolonged longer than necessary, the methyl-butenes are in turn hydrogenated to isopentane. The hydrogen consumption is also monitored over time by the decrease in pressure in a reservoir bottle located upstream of the reactor. The catalytic activity is expressed in moles of H2 consumed per minute and per gram of Cu. The initial catalytic activities measured for catalysts A to E are reported in Table 1 below. They are expressed in 10 -3 mol isoprene converted per second per gram of catalyst.

[0143] Activity = 10 -3. mol isoprene (initial)- mol isoprene (t) / t / catalyst mass The conversion of isoprene is determined according to the following formula: Conversion (t, %) = 100*[1- (mol isoprene (t) / mol isoprene (initial))] The selectivity is represented by the selectivity to methyl-butenes: Selectivity (% mol) = (methyl-butenes) / (methyl-butenes + isopentane)

[0144] The methyl-butene selectivity of the catalysts is compared to 85% conversion of isoprene.

[0145] Table 1: Comparison of the performance of catalysts A to E in the selective hydrogenation of a mixture containing isoprene. Monometallic catalyst B (non-compliant) comprising only indium is inactive for the reaction. Catalysts C and D, in accordance with the invention, are very selective for the selective hydrogenation of isoprene compared to non-compliant catalyst A. The addition of indium makes it possible to reduce the quantity of alkene formed at iso-conversion of isoprene. Furthermore, catalyst D has very good activity, and catalyst C has acceptable activity. Catalyst E, although equally active due to the same copper content, is not at all selective. Indeed, the excessively high specific surface area of ​​alumina leads to copper and indium species isolated from each other. However, the selectivity obtained by the catalysts according to the invention is linked to a strong interaction between the copper and indium atoms.

Claims

Claims 1. Catalyst comprising an active phase comprising copper and an element from 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 from column IIIA being between 1 and 50 mol / mol, characterized in that said support is in the form of a ball or an extrudate comprising a specific surface area of ​​between 10 m 2 / g and 250 m 2 / g.

2. Catalyst according to claim 1, in which the element of column III A is chosen from indium or gallium.

3. Catalyst 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. Catalyst 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. A catalyst according to any one of claims 1 to 3, wherein when element IIIA is indium, the copper and indium are present in the form of an alloy.

6. Catalyst according to any one of claims 1 to 5, characterized in that said support is an extrudate comprising three lobes or four lobes.

7. Catalyst according to any one of the preceding claims, characterized in that the specific surface area of ​​said support is between 160 m 2 / g and 210 m 2 / g.

8. A method for preparing a catalyst according to any one of the preceding claims, comprising the following steps: a) an alumina gel is supplied; b) the alumina gel from step a) is shaped to form an alumina support; c) the following sequence is carried out to obtain a catalyst precursor: c1) the alumina support is brought into contact with a solution comprising at least one precursor of the active copper phase; c2) the alumina support is brought into contact with at least one solution comprising at least one precursor of the active phase based on an element from column 11 IA; steps c1) and c2) being carried out separately, in any order, or simultaneously; d) the catalyst precursor obtained at the end of step c) is dried at a temperature below 250°C to obtain a dried catalyst precursor.

9. Method according to claim 8, in which the shaped alumina gel obtained at the end of step b) is subjected to a heat treatment comprising at least one hydrothermal treatment step in an autoclave in the presence of an acid solution, at a temperature between 100°C and 800°C, then to at least one calcination step, at a temperature between 400°C and 1500°C, carried out after the hydrothermal treatment step, to obtain said alumina support.

10. Method according to any one of claims 8 or 9, in which when steps c1) and c2) are carried out separately in any order, an intermediate drying step is carried out between steps c1) and c2), or between steps c2) and c1), in which the catalyst precursor obtained at the end of step c1), or of step c2), is dried at a temperature below 250°C.

11. Method according to claim 10, 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.

12. Method according to any one of claims 8 or 9, in which steps c1) and c2) are carried out simultaneously.

13. A method according to any one of claims 8 to 12, 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.

14. Method according to any one of claims 8 to 13, in which the element I HA of the active phase is indium, and the precursor of the active indium phase is 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.

15. A method according to any one of claims 8 to 13, wherein the element II IA of the active phase is gallium, and the precursor of the gallium active phase 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, organic precursors such as gallium triethyl and gallium trimethyl.

16. 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 h -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 h -1 and 40,000 h -1 when the process is carried out in the gas phase, in the presence of a catalyst according to any one of claims 1 to 7, or obtained by a preparation process according to any one of claims 8 to 15.

Images