Novel heterogeneous bimetallic catalyst, its preparation process and its use in the synthesis of ethylene glycol from carbon monoxide

Abstract

The present invention relates to the use of a supported bimetallic catalyst of the formula Pd-M / support, comprising palladium and the metal M on a support, where M represents Cu or Ag, in carrying out a process for the preparation of ethylene glycol from alcohol, comprising two reaction steps catalyzed by said same bimetallic catalyst.

Description

[Technical field]

[0001] The present invention relates to a novel heterogeneous bimetallic catalyst, a process for its preparation and its use in the synthesis of ethylene glycol from carbon monoxide. [Background technology]

[0002] Ethylene glycol is an important material in the chemical industry, enabling the production of textile fibers and polyester resins. One method of synthesizing ethylene glycol is by hydrogenating oxalate.

[0003] Oxalates are high added value raw materials in the chemical industry. They are used on a large scale in the fine chemical industry to produce various dyes, pharmaceuticals, solvents, extractants and various intermediates.

[0004] The conventional production method of oxalates involves the esterification of oxalic acid with alcohol, a production technique that is costly, energy intensive, polluting, and involves irrational use of raw materials.

[0005] Generally, the carbonylation reaction from CO leading to the formation of oxalates and the hydrogenation reaction of oxalates to ethylene glycol are catalyzed by two completely different catalysts. For example, the carbonylation step is generally carried out with a heterogeneous palladium-based catalyst, whereas the hydrogenation step is carried out with a copper-based catalyst. However, copper does not catalyze the formation of oxalates, and palladium does not allow the hydrogenation of oxalic acid derivatives to ethylene glycol. Thus, the two steps use very different catalysts with different transition metals, which may pose a major challenge in large-scale industrial processes.

[0006] There has long been a need for a low-cost, environmentally friendly method for producing ethylene glycol.

[0007] So far, heterogeneous catalysts have been sought that would enable efficient synthesis of ethylene glycol in an environmentally friendly, easy to industrialize and safe manner.

[0008] The use of a catalyst capable of catalyzing the carbonylation reaction of an alcohol to oxalate and simultaneously catalyzing the hydrogenation reaction of the oxalate to ethylene glycol in a process for preparing ethylene glycol would be of commercial interest and advantage from both a practical and material standpoint. Summary of the Invention [Problem to be solved by the invention]

[0009] One of the objects of the present invention is to propose a process for the preparation of ethylene glycol in two catalytic reaction steps using a single catalyst of the same nature, said two reaction steps being the carbonylation of an alcohol to an oxalate and the hydrogenation of the oxalate to ethylene glycol.

[0010] Another object of the present invention is a process for preparing ethylene glycol in efficient yield and high selectivity in two reaction steps, carbonylation and hydrogenation.

[0011] Another object of the present invention is to prepare ethylene glycol without the use of toxic reagents such as nitro derivatives.

[0012] Another object of the present invention is the preparation of ethylene glycol using recyclable or recycled reagents such as CO2 or CO and an efficient and reusable heterogeneous catalyst.

[0013] It is another object of the present invention to provide novel heterogeneously supported bimetallic catalysts.

[0014] It is another object of the present invention to provide a heterogeneous catalyst that can be used in a continuous flow process.

[0015] Another object of the present invention is to propose a simple, industrially suitable and optimized preparation process for this catalyst. [Means for solving the problem]

[0016] A first subject of the present invention is the use of a supported bimetallic catalyst of formula Pd-M / support, comprising palladium and the metal M on a support, where M represents Cu or Ag, in carrying out a process for preparing ethylene glycol from alcohol, comprising two reaction steps catalyzed by the same bimetallic catalyst, in particular the first catalytic reaction step is an oxidative carbonylation from an alcohol, carbon monoxide and an oxidant, particularly molecular oxygen, optionally in the presence of a promoter, to form an oxalate compound as a reaction intermediate; and the second catalytic reaction step is hydrogenation of the oxalate compound with hydrogen to obtain ethylene glycol; It is use.

[0017] For the purposes of the present invention, "the same catalyst" means a catalyst of the same nature, a catalyst whose properties, i.e. in particular the physical, chemical and surface properties, in particular the nature of the metals and the support, their proportions, the size and morphology of the particles are identical to those of the catalyst referred to.

[0018] The inventors have unexpectedly observed the possibility of using supported bimetallic palladium-copper or palladium-silver catalysts to catalyze the carbonylation reaction of alcohols to oxalates and the hydrogenation reaction of oxalates to ethylene glycol. Both reactions can be carried out without pretreatment of the catalyst by a metal reduction step under hydrogen. Combining palladium with copper or silver (two metals in the same column as gold in the periodic table of the elements) makes it possible to obtain a catalyst capable of catalyzing the carbonylation and hydrogenation reactions carried out in the process for preparing ethylene glycol from alcohols.

[0019] According to one particular embodiment, the invention relates to the use of a supported bimetallic catalyst of the formula Pd-Cu / support in carrying out a process for the preparation of ethylene glycol from alcohols comprising two reaction steps catalyzed by the same bimetallic catalyst, in particular the first catalytic reaction step is an oxidative carbonylation from an alcohol, carbon monoxide and an oxidant, particularly molecular oxygen, optionally in the presence of a promoter, to form an oxalate compound as a reaction intermediate; and the second catalytic reaction step is hydrogenation of the oxalate compound with hydrogen to obtain ethylene glycol; Regarding use.

[0020] The inventors have also unexpectedly observed that the use of a bimetallic Pd-Cu / ZrO2 catalyst makes it possible to obtain higher yields of the oxidative carbonylation and hydrogenation reaction steps in the preparation of ethylene glycol than those obtained with the corresponding monometallic Pd / ZrO2 and Cu / ZrO2 catalysts, demonstrating the synergistic effect of the bimetallic catalysts for carbonylation and hydrogenation.

[0021] According to one particular embodiment, the invention relates to the use of a supported bimetallic catalyst of the formula Pd-Ag / support in carrying out a process for the preparation of ethylene glycol from alcohols comprising two reaction steps catalyzed by the same bimetallic catalyst, in particular the first catalytic reaction step is an oxidative carbonylation from an alcohol, carbon monoxide and an oxidant, particularly molecular oxygen, optionally in the presence of a promoter, to form an oxalate compound as a reaction intermediate; and the second catalytic reaction step is hydrogenation of the oxalate compound with hydrogen to obtain ethylene glycol; Regarding use.

[0022] The present invention is based on the use of the same catalyst, i.e. a catalyst having the same properties, capable of catalyzing two different reaction steps used in the ethylene glycol preparation process, specifically the oxidative carbonylation reaction step and the hydrogenation step.

[0023] For the purposes of the present invention, a "Pd-M bimetallic catalyst" means a catalyst whose catalytic sites comprise palladium and a metal M, where M is Cu or Ag. Palladium and metal M combine to form catalytic sites which are operative during two catalytic reaction steps. Bimetallic catalysts according to the present invention include catalysts in which the two metals are in the form of a core-shell structure or in the form of a homogeneous alloy, or in the form of two distinct particle populations of palladium and metal M, respectively, or in the form of a mixture of these different morphological populations.

[0024] The Pd-M / support catalyst is understood to be a heterogeneous catalyst.

[0025] The use of heterogeneous catalysts has the advantage that it facilitates separation of the catalyst from other species participating in the reaction, making it easier to recover and reuse the catalyst.

[0026] The use of heterogeneous catalysts also has the advantage that it makes it possible to fix the catalyst in an enclosure, such as a cartridge, in the reactor when operating under continuous flow, thus obtaining a catalyst-free product at the outlet of the reactor.

[0027] For the purposes of this invention, a "reaction step" means a synthesis step that involves a chemical reaction with a starting reagent to form a final product. The chemical reaction leads to a change in the molecular structure of the starting reagent. Carbonylation and hydrogenation are understood to be reaction steps. On the other hand, product recovery, washing or purification steps are not considered as reaction steps.

[0028] A reaction step is said to be catalyzed if it requires a catalyst for its execution.

[0029] For the purposes of the present invention, "the same catalyst" means a catalyst of the same nature, with the same properties such as the nature of the metal and the support and their proportions.

[0030] Therefore, one of the industrial advantages is that only one type of catalyst can be used or prepared, limiting the raw material or catalyst preparation steps required for the ethylene glycol preparation process. The limited number of raw materials means that purchasing costs and waste management can be optimized. The limited number of industrial steps is advantageous from the standpoint of cost and process implementation.

[0031] In one particular embodiment, the invention relates to the use as defined above, in which the catalyst support is an oxide.

[0032] Oxide supports are commonly used to prepare heterogeneous catalysts, in part because of the efficient catalytic properties they provide, and in part because they are readily available and easy to prepare, e.g., they are advantageously inexpensive compared to polymer supports.

[0033] In one particular embodiment, the invention relates to the use as defined above, in which the catalyst support is an oxide selected from among zirconium dioxide ZrO2, alumina Al2O3, silica SiO2, cerium dioxide CeO2, titanium dioxide TiO2, magnesium oxide MgO, indium oxide In2O3 or a mixture of these oxides, preferably zirconium dioxide ZrO2.

[0034] In one particular embodiment, the invention relates to the use as defined above, in which the catalyst support is an oxide selected from among zirconium dioxide ZrO2, alumina Al2O3, and silica SiO2.

[0035] In one particular embodiment, the invention relates to the use as defined above, wherein said supported bimetallic catalyst is a Pd-Cu / ZrO2 catalyst.

[0036] In one particular embodiment, the zirconium dioxide support ZrO2 has a melting temperature of 2700 to 2750 °C, in particular 2715 °C, and a viscosity of 5 to 6 g / cm 3 has a density of

[0037] Zirconium dioxide supports are available, for example, from STERM Chemicals, 15 Rue de l'Atome, 67800 Bischheim.

[0038] The Pd-Cu bimetallic catalyst is preferably supported on zirconium dioxide ZrO2, although other types of supports based on other oxides such as Al2O3, SiO2, CeO2, TiO2, MgO, In2O3, etc. are also possible.

[0039] In one particular embodiment, the oxide support of the Pd-M bimetallic catalyst is in the form of a layer on the surface of another inert, ie chemically inactive, material, such as ceramic or glass.

[0040] In one particular embodiment, the invention relates to the use as defined above, in which the catalyst has a palladium content of 0.1 to 10%, in particular 2%, and a content of metal M of 0.1 to 40%, in particular 10% or 15%, in % by weight relative to the total weight of the catalyst.

[0041] It is understood that the ratio between the total content of metal Pd-M and the support varies in the catalyst of the invention from 0.2% to 50% by weight, the weight of the metal representing at most half the total weight of the catalyst.

[0042] The expression "0.1-10%" corresponds to the following ranges: 0.1-1%; 1-2%; 2-3%; 3-4%; 4-5%; 5-6%; 6-7%; 7-8%; 8-9%; 9-10%.

[0043] The expression "0.1-40%" corresponds to the following ranges: 0.1-5%; 5-10%; 10-15%; 15-20%; 20-25%; 25-30%; 30-35%; 35-40%.

[0044] In one particular embodiment, the present invention relates to the use as defined above, wherein the weight ratio of Pd to M is between 1:1 and 1:20, preferably between 1:1 and 1:10, more preferably 1:5.

[0045] The expression "1:1 - 1:20" corresponds to the following ranges: 1:1 - 1:2, 1:2 - 1:3, 1:3 - 1:4, 1:4 - 1:5, 1:5 - 1:6, 1:6 - 1:7, 1:7 - 1:8, 1:8 - 1:9, 1:9 - 1:10, 1:10 - 1:11, 1:11 - 1:12, 1:12 - 1:13, 1:13 - 1:14, 1:14 - 1:15, 1:15 - 1:16, 1:16 - 1:17, 1:17 - 1:18, 1:18 - 1:19, 1:19 - 1:20.

[0046] In one particular embodiment, the present invention relates to the use as defined above, wherein the first catalytic reaction step is the oxidative carbonylation from an alcohol, carbon monoxide and an oxidizing agent, in particular molecular oxygen, optionally in the presence of a promoter, to form an oxalate compound as a reaction intermediate, and the second catalytic reaction step is the hydrogenation reaction of said oxalate compound with hydrogen to obtain ethylene glycol.

[0047] The overall diagram of the preparation process according to the present invention can be represented as follows:

[0048] [ka]

[0049] "Oxalate" refers to the dialkyl oxalate (DAO) corresponding to the alcohol used.

[0050] A "promoter" or "reaction promoter" is a substance that can improve the properties of a catalyst, such as catalytic activity, selectivity, stability, lifetime, etc., or prevent deactivation of the catalyst.

[0051] In one particular embodiment, the promoter is an oxidizing agent, and thus the promoter is capable of promoting the oxidative carbonylation process.

[0052] According to one particular embodiment, the invention relates to the use as defined above, in which the performance of the oxidative carbonylation reaction step comprises at least one additive.

[0053] By "additive" is meant a substance that improves the yield of a reaction but is not essential for the reaction to occur. An additive does not directly participate in the transformation of the substrate and therefore does not enter into the equilibrium equation of the reaction.

[0054] According to one particular embodiment, the additive is a base, preferably chosen from among triethylamine (Et3N), 2,6-lutidine, cesium carbonate (Cs2CO3) or 1-methylimidazole.

[0055] Another subject of the present invention is a first reaction step A of oxidative carbonylation of an alcohol in the presence of a supported bimetallic catalyst of the formula Pd-M / support, where M represents Cu or Ag, to obtain an oxalate compound as a reaction intermediate; a second reaction step B of hydrogenation of the oxalate compound, optionally purified, produced in reaction step A, to ethylene glycol in the presence of the catalyst of formula Pd-M / support; The present invention relates to a method for preparing ethylene glycol, comprising the steps of:

[0056] Reaction step A, which corresponds to the oxidative carbonylation of an alcohol, is diagrammed as follows:

[0057] [ka]

[0058] Reaction step B, which corresponds to the hydrogenation of the oxalate compound (DAO), is diagrammed as follows:

[0059] [ka]

[0060] According to one particular embodiment, the present invention provides a method for producing a cellular membrane comprising: ● Reaction step A is - alcohols, in particular alcohols chosen from methanol and ethanol, - Carbon monoxide, - an oxidizer, specifically oxygen O2, - catalysts of the formula Pd-M / support, where M represents Cu or Ag, in particular catalysts comprising an oxide support selected from among zirconium dioxide ZrO2, alumina Al2O3, silica SiO2, cerium dioxide CeO2, titanium dioxide TiO2, magnesium oxide MgO, indium oxide In2O3 or mixtures of these oxides, preferably catalysts of the formula Pd-Cu / ZrO2; optionally a promoter, in particular an iodine compound selected in particular from among tetramethylammonium iodide, potassium iodide or sodium iodide, preferably tetramethylammonium iodide, optionally a base, in particular triethylamine, optionally a solvent, in particular a solvent chosen from among acetonitrile, tetrahydrofuran, dioxane and toluene, preferably acetonitrile, to obtain a reaction medium 1, which can be pressurized to 0.1 to 15 MPa; Optionally, said reaction medium 1 is heated at a temperature between 25 and 200° C., preferably at about 90° C., in particular for a period between 2 and 24 hours, preferably 16 hours, Obtaining an oxalate compound; Contains; ● Reaction step B is ○- the oxalate compound, - dihydrogen, said catalyst of the formula Pd-M / support, where M represents Cu or Ag, optionally a solvent, in particular ethanol, methanol and dioxane, preferably ethanol or methanol, to obtain a reaction medium 2, which may be pressurized to between 0.1 and 15 MPa, in particular to 5 MPa; Optionally, said reaction medium 2 is heated to a temperature between 100 and 250° C., in particular 200 or 220° C., for a period of preferably between 5 and 24 hours, more preferably 8 or 16 hours, obtaining ethylene glycol; Contains The present invention relates to a process for preparing ethylene glycol as defined above.

[0061] According to one particular embodiment, the present invention provides a method for producing a cellular membrane comprising: ● Reaction step A is ○- Alcohol, - Carbon monoxide, - oxidizing agents, - catalysts of the formula Pd-M / support, where M represents Cu or Ag; - optionally a promoter, optionally a base, optionally a solvent, to obtain a reaction medium 1, which can be pressurized to 0.1 to 15 MPa; Optionally, the reaction medium may be heated, Obtaining an oxalate compound; Contains; ● Reaction step B is ○- the oxalate compound, - dihydrogen, said catalyst of the formula Pd-M / support, where M represents Cu or Ag, optionally a solvent, to obtain a reaction medium 2, which may be pressurized to between 0.1 and 15 MPa, in particular to 5 MPa; optionally, said reaction medium 2 is heated, obtaining ethylene glycol; Contains It relates to a method as defined above.

[0062] solvent The process according to the invention has the advantage that no solvent is required in reaction step A, which is the oxidative carbonylation of the alcohol. Advantageously, the alcohol can act as both a reagent and a solvent in reaction step A.

[0063] According to one particular embodiment, the present invention provides a method for producing a cellular membrane comprising: ● Reaction step A is ○- Alcohol, - Carbon monoxide, - oxidizing agents, - catalysts of the formula Pd-M / support, where M represents Cu or Ag; - accelerators, - bases, optionally a solvent, to obtain a reaction medium 1 pressurized to 0.1 to 15 MPa, in particular 8 MPa; heating the reaction medium, Obtaining an oxalate compound; Contains; ● Reaction step B is ○- the oxalate compound, - dihydrogen, said catalyst of the formula Pd-M / support, where M represents Cu or Ag, - solvent, to obtain a reaction medium 2 pressurized to a pressure of 0.1 to 15 MPa, in particular 5 MPa; said reaction medium 2 is heated, obtaining ethylene glycol; Contains It relates to a method as defined above.

[0064] Advantageously, the oxidative carbonylation reaction step A of the process according to the invention can be carried out in the absence of a solvent.

[0065] According to one particular embodiment, the present invention provides a method for producing a cellular membrane comprising: ● Reaction step A is ○- Alcohol, - Carbon monoxide, - oxidizing agents, - catalysts of the formula Pd-M / support, where M represents Cu or Ag; - accelerators, - bases, to obtain a reaction medium 1 pressurized to 0.1 to 15 MPa, in particular 8 MPa; heating the reaction medium, Obtaining an oxalate compound; Contains; ● Reaction step B is ○- the oxalate compound, - dihydrogen, said catalyst of the formula Pd-M / support, where M represents Cu or Ag, - solvent, to obtain a reaction medium 2, which may be pressurized to between 0.1 and 15 MPa, in particular to 5 MPa; heating the reaction medium, obtaining ethylene glycol; Contains It relates to a method as defined above.

[0066] Advantageously, the oxidative carbonylation reaction step A of the process according to the invention can be carried out in the presence of a solvent.

[0067] According to one particular embodiment, the present invention provides a method for producing a cellular membrane comprising: ● Reaction step A is ○- Alcohol, - Carbon monoxide, - oxidizing agents, - catalysts of the formula Pd-M / support, where M represents Cu or Ag; - accelerators, - bases, - solvent, to obtain a reaction medium 1 pressurized to 0.1 to 15 MPa, in particular 8 MPa; heating the reaction medium, Obtaining an oxalate compound; Contains; ● Reaction step B is ○- the oxalate compound, - dihydrogen, said catalyst of the formula Pd-M / support, where M represents Cu or Ag, - solvent, to obtain a reaction medium 2 pressurized to a pressure of 0.1 to 15 MPa, in particular 5 MPa; heating the reaction medium, obtaining ethylene glycol; Contains It relates to a method as defined above.

[0068] "Reaction medium" means all species taken together in a chemical reaction, including in particular reagents in liquid or gaseous form, catalysts, and optionally solvents, additives, or promoters.

[0069] The expression MPa is 10 6 It corresponds to a pascal and is equivalent to 10 bar.

[0070] The expression "0.1-15.0MPa" corresponds to the following ranges: 0.1-0.5MPa; 0.5-1.0MPa; 1.0-1.5MPa; 1.5-2.0MPa; 2.0-2.5MPa; 2.5-3.0MPa; 3.0-3.5MPa; 3.5-4.0MPa; 4.0-4.5MPa; 4.5-5.0MPa; 5.0-5.5MPa; 5.5-6.0MPa; 6.0-6.5MPa; 6.5-7.0MPa; 7.0-7. 5MPa;7.5~8.0MPa;8.0~8.5MPa;8.5~9.0MPa;9.0~9.5MPa;9.5~10.0MPa;10.0~10.5MPa;10.5~11.0MPa;11.0~11. 5MPa;11.5~12.0MPa;12.0~12.5MPa;12.5~13.0MPa;13.0~13.5MPa;13.5~14.0MPa;14.0~14.5MPa;14.5~15.0MPa.

[0071] According to one particular embodiment, the present invention relates to a process as defined above, wherein the alcohol used in reaction step A is also used as solvent in reaction step B.

[0072] Advantageously, thus, the alcohol in the oxalate product obtained in reaction step A does not need to be evaporated before use as a reagent in reaction step B.

[0073] base The process according to the invention has the advantage that no base is required in reaction step A, which is the oxidative carbonylation of the alcohol. Indeed, advantageously, a base is an additive which promotes the efficiency of the reaction but is not necessary to carry out reaction step A.

[0074] According to one particular embodiment, the present invention provides a method for producing a cellular membrane comprising: ● Reaction step A is ○- Alcohol, - Carbon monoxide, - oxidizing agents, - catalysts of the formula Pd-M / support, where M represents Cu or Ag; - accelerators, optionally a base, - solvent, to obtain a reaction medium 1 pressurized to 0.1 to 15 MPa, in particular 8 MPa; heating the reaction medium, Obtaining an oxalate compound; Contains; ● Reaction step B is ○- the oxalate compound, - dihydrogen, said catalyst of the formula Pd-M / support, where M represents Cu or Ag, - solvent, to obtain a reaction medium 2 pressurized to a pressure of 0.1 to 15 MPa, in particular 5 MPa; said reaction medium 2 is heated, obtaining ethylene glycol; Contains It relates to a method as defined above.

[0075] Advantageously, the oxidative carbonylation reaction step A of the process according to the invention can be carried out in the absence of a base.

[0076] According to one particular embodiment, the present invention provides a method for producing a cellular membrane comprising: ● Reaction step A is ○- Alcohol, - Carbon monoxide, - oxidizing agents, - catalysts of the formula Pd-M / support, where M represents Cu or Ag; - accelerators, - solvent, to obtain a reaction medium 1 pressurized to 0.1 to 15 MPa, in particular 8 MPa; heating the reaction medium, Obtaining an oxalate compound; Contains; ● Reaction step B is ○- the oxalate compound, - dihydrogen, said catalyst of the formula Pd-M / support, where M represents Cu or Ag, - solvent, to obtain a reaction medium 2 pressurized to a pressure of 0.1 to 15 MPa, in particular 5 MPa; said reaction medium 2 is heated, obtaining ethylene glycol; Contains It relates to a method as defined above.

[0077] Other process parameters According to a particular embodiment, the invention relates to a process as defined above, wherein said catalyst comprises an oxide support, preferably zirconium dioxide ZrO2, alumina Al2O3, silica SiO2, cerium dioxide CeO2, titanium dioxide TiO2, magnesium oxide MgO, indium oxide In2O3 or a mixture of these oxides.

[0078] According to a particular embodiment, the present invention relates to a process as defined above, wherein said catalyst is of formula Pd-Cu / ZrO2.

[0079] According to a particular embodiment, the invention relates to a process as defined above, in which the catalyst has a palladium content of between 0.1 and 10%, in particular 2%, and a content of metal M of between 0.1 and 40%, in particular 10%, in % by weight relative to the total weight of the catalyst.

[0080] According to one particular embodiment, the invention relates to a process as defined above, in which in reaction step A, a catalyst is used in a proportion of palladium between 0.01 and 10 mol % relative to the alcohol.

[0081] The expression "0.01-10%" corresponds to the following ranges: 0.01-0.05%; 0.05-0.1%; 0.1-0.15%; 0.15-0.2%; 0.2-0.5%; 0.5-1%; 1-2%; 2-3%; 3-4%; 4-5%; 5-6%; 6-7%; 7-8%; 8-9%; 9-10%.

[0082] According to one particular embodiment, the present invention relates to a process as defined above, wherein carbon monoxide is used in reaction step A at a pressure between 0.5 and 8.0 MPa, in particular at 6.5 MPa.

[0083] The expression "0.5~8.0MPa" corresponds to the following ranges: 0.5~1.0MPa; 1.0~1.5MPa; 1.5~2.0MPa; 2.0~2.5MPa; 2.5~3.0MPa; 3.0~3.5MPa; 3.5~4.0MPa; 4.0~4.5MPa; 4.5~5.0MPa; 5.0~5.5MPa; 5.5~6.0MPa; 6.0~6.5MPa; 6.5~7.0MPa; 7.0~7.5MPa; 7.5~8.0MPa.

[0084] According to one particular embodiment, the invention relates to a process as defined above, in which the oxidizing agent in reaction step A is oxygen, used at a pressure between 0.5 and 2.5 MPa, in particular at 1.5 MPa.

[0085] The expression "0.5-2.5 MPa" corresponds to the following ranges: 0.5-1.0 MPa; 1.0-1.5 MPa; 1.5-2.0 MPa; 2.0-2.5 MPa.

[0086] According to a particular embodiment, the invention relates to a method as defined above, in which the oxidizing agent is chosen among molecular oxygen (O2), air, diones, in particular 1,4-benzoquinone, 1,4-dichloro-2-butene and CuCl2.

[0087] It is understood that air containing 20% ​​O2 can be used to carry out processes in which O2 is the oxidizing agent.

[0088] According to one particular embodiment, the present invention relates to a process as defined above, in which in reaction step A a promoter is used, in particular an iodine compound, in particular an iodine compound selected among tetramethylammonium iodide, potassium iodide or sodium iodide.

[0089] According to one particular embodiment, the invention relates to a process as defined above, in which the promoter is used in a proportion between 0.1 and 5 mol %, in particular in a proportion of 0.2 mol %, relative to the alcohol.

[0090] The expression "0.1-5%" corresponds to the following ranges: 0.1-0.15%; 0.15-0.2%; 0.2-0.3%; 0.3-0.4%; 0.4-0.5%; 0.5-1%; 1-2%; 2-3%; 3-4%; 4-5%.

[0091] According to one particular embodiment, the present invention relates to a process as defined above, in which in reaction step A, a base is used, in particular triethylamine.

[0092] According to one particular embodiment, the invention relates to a process as defined above, in which the base is used in a proportion between 0.1 and 5 mol %, in particular in a proportion of 0.15 mol %, relative to the alcohol.

[0093] The expression "0.1-5%" corresponds to the following ranges: 0.1-0.15%; 0.15-0.2%; 0.2-0.3%; 0.3-0.4%; 0.4-0.5%; 0.5-1%; 1-2%; 2-3%; 3-4%; 4-5%.

[0094] According to one particular embodiment, the present invention relates to a process as defined above, in which in reaction step A a solvent is used, in particular a solvent selected from among acetonitrile, tetrahydrofuran, dioxane and toluene, preferably acetonitrile.

[0095] According to one particular embodiment, the invention relates to a process as defined above, in which, in reaction step A, the reaction medium 1 is pressurized to a pressure between 0.1 and 15 MPa, preferably about 8 MPa.

[0096] According to a particular embodiment, the invention relates to a process as defined above, in which, in reaction step A, the reaction medium 1 is heated at a temperature between 25 and 200° C., in particular between 60 and 110° C., preferably at about 90° C., in particular for a period of 2 to 24 hours, preferably for 16 hours.

[0097] The expression "25~200°C" corresponds to the following ranges: 25~40°C; 40~60°C; 60~80°C; 80~100°C; 100~120°C; 120~140°C; 140~160°C; 160~180°C; 180~200°C.

[0098] The expression "60~110°C" corresponds to the following ranges: 60~70°C; 70~80°C; 80~90°C; 90~100°C; 100~110°C.

[0099] The expression "2 to 24 hours" corresponds to the following ranges: 2 to 5 hours; 5 to 8 hours; 8 to 12 hours; 12 to 16 hours; 16 to 20 hours; 20 to 24 hours.

[0100] In one particular embodiment, the present invention relates to a process for producing a compound comprising the steps of: [ka] to prepare an oxalate compound of formula 2, In the formula, R a but: ● C1~C 20 a linear or branched alkyl group of ● C3~C 10 a cycloalkyl group of the formula: ● C5~C 20 an alkylaryl or alkylheteroaryl group of the formula wherein

[0101] For the purposes of this invention, "C1-C 20 By "straight-chain or branched alkyl group" is meant a saturated straight-chain or branched acyclic carbon chain containing from 1 to 20 carbon atoms. These groups are methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, cetyl, heptadecyl, octadecyl, nonadecyl and eicosyl.

[0102] The definition of alkyl includes all possible isomers. For example, the term butyl includes n-butyl, iso-butyl, sec-butyl and ter-butyl. One or more hydrogen atoms may be replaced in the alkyl chain.

[0103] "C3~C 10 "Cycloalkyl" means a C3 cyclopropyl group, a C4 cyclobutyl group, a C5 cyclopentyl group, a C6 cyclohexyl group, a C7 cycloheptyl group, a C8 cyclooctyl group, a C9 cyclononyl group, or a C 10 It refers to cyclodecyl groups and fused cycloalkane rings, for example adamantyl.

[0104] "C5~C 20 "Alkylaryl" refers to a group consisting of a linear or branched alkyl chain attached to an aromatic group, the alkylaryl group containing 5 to 20 carbon atoms. The aryl group according to the invention is also particularly C1-C 10 It can be substituted with one or more substituents selected from straight-chain or branched alkyl groups.

[0105] Phenyl, toluyl, anisyl and naphthyl, o-tolyl, m-tolyl, p-tolyl, o-xylyl, m-xylyl, p-xylyl are examples of aryl groups.

[0106] The term "heteroaryl" refers to an aryl group as defined above that contains an atom other than carbon atom in the aromatic ring, in particular N, O or S. Pyridyl, imidazoyl, furfuryl or furanyl are examples of heteroaryl groups according to the invention.

[0107] In one particular embodiment, the present invention relates to an alcohol in which the reaction step A is in particular selected from among methanol, ethanol and isopropanol, [ka] to prepare an oxalate compound of formula 2, In the formula, Ra but: ● C1~C 20 a linear or branched alkyl group of ● C3~C 10 a cycloalkyl group of the formula: ● C5~C 20 an alkylaryl or alkylheteroaryl group of the formula wherein

[0108] According to a particular embodiment, the present invention relates to a process as defined above, in which a purification step of said oxalate compound is carried out between reaction step A and reaction step B, in particular by distillation.

[0109] Advantageously, the purification step of the oxalate compound is carried out by distillation, extraction or recrystallization within the purification step.

[0110] According to a particular embodiment, the present invention relates to a process as defined above, wherein in reaction step B, the catalyst is used in an amount of 0.5 to 10 mmol, in particular 4 mmol, Cu or Ag.

[0111] The expression "0.5 to 10 mmol" corresponds to the following ranges: 0.5 to 1 mmol; 1 to 2 mmol; 2 to 3 mmol; 3 to 4 mmol; 4 to 5 mmol; 5 to 6 mmol; 6 to 7 mmol; 7 to 8 mmol; 8 to 9 mmol; 9 to 10 mmol.

[0112] According to a particular embodiment, the invention relates to a process as defined above, in which in reaction step B, the oxalate compound is used in an amount between 2 and 40 molar equivalents, in particular in a proportion of 5 equivalents, relative to the metal M of the catalyst.

[0113] The expression "2 to 40 equivalents" corresponds to the following ranges: 2 to 5 equivalents; 5 to 10 equivalents; 10 to 15 equivalents; 15 to 20 equivalents; 20 to 25 equivalents; 25 to 30 equivalents; 30 to 35 equivalents; 35 to 40 equivalents.

[0114] According to one particular embodiment, the present invention relates to a process as defined above, wherein in reaction step B, dihydrogen is used under a pressure between 1.0 and 8.0 MPa, in particular 5.0 MPa.

[0115] The expression "1.0~8.0MPa" corresponds to the following ranges: 1.0~1.5MPa; 1.5~2.0MPa; 2.0~2.5MPa; 2.5~3.0MPa; 3.0~3.5MPa; 3.5~4.0MPa; 4.0~4.5MPa; 4.5~5.0MPa; 5.0~5.5MPa; 5.5~6.0MPa; 6.0~6.5MPa; 6.5~7.0MPa; 7.0~7.5MPa; 7.5~8.0MPa.

[0116] According to one particular embodiment, the present invention relates to a process as defined above, wherein in reaction step B, the solvent is selected among ethanol, methanol and dioxane, preferably ethanol or methanol.

[0117] According to a particular embodiment, the invention relates to a process as defined above, in which, in reaction step B, the reaction medium 2 is pressurized to a pressure between 1.0 and 8.0 MPa, in particular to 5 MPa.

[0118] According to a particular embodiment, the invention relates to a process as defined above, in which, in reaction step B, the reaction medium 2 is heated to a temperature between 100 and 250° C., in particular to 200 or 220° C., preferably for a period of 5 to 24 hours, more preferably for 8 or 16 hours.

[0119] The expression "100~250°C" corresponds to the following ranges: 100~120°C; 120~140°C; 140~160°C; 160~180°C; 180~200°C; 200~220°C; 220~250°C.

[0120] The expression "5 to 24 hours" corresponds to the following ranges: 5 to 8 hours; 8 to 12 hours; 12 to 16 hours; 16 to 20 hours; 20 to 24 hours.

[0121] Catalyst Reuse Reaction step B of the process of the invention is advantageously carried out without any additives in the reaction medium.

[0122] Advantageously, the catalyst recovered after reaction step B of the present invention is not degraded, is stable and in particular does not contain additives. It can advantageously be reused as a catalyst in another catalytic reaction step. It is therefore possible to repeat reaction step B of the present invention several times with the recovered catalyst or to carry out reaction step A with the catalyst recovered from reaction step B.

[0123] According to one particular embodiment, the present invention relates to a process for the preparation of ethylene glycol as defined above, wherein the catalyst is recovered at the end of reaction step B and reused as catalyst in another catalytic reaction step.

[0124] According to one particular embodiment, the present invention relates to a process for the preparation of ethylene glycol as defined above, wherein the catalyst is recovered at the end of reaction step B and reused as catalyst in another subsequent reaction step B.

[0125] Advantageously, the catalyst recovered at the end of reaction step B can be used for several successive cycles of reaction step B.

[0126] According to a particular embodiment, the present invention relates to a process for the preparation of ethylene glycol as defined above, wherein the catalyst is recovered at the end of reaction step B and reused as catalyst in reaction step A.

[0127] According to a particular embodiment, the present invention relates to a process for the preparation of ethylene glycol as defined above, wherein the catalyst used in reaction step A is the catalyst recovered at the end of reaction step B.

[0128] According to a particular embodiment, the present invention relates to a process for the preparation of ethylene glycol as defined above, wherein the catalyst is recovered at the end of reaction step A and reused as catalyst in reaction step B.

[0129] According to a particular embodiment, the present invention relates to a process for the preparation of ethylene glycol as defined above, wherein the catalyst used in reaction step B is the catalyst recovered at the end of reaction step A.

[0130] According to one particular embodiment, the present invention relates to a process for the preparation of ethylene glycol as defined above, wherein the catalyst is recovered at the end of reaction step A and reused as catalyst in a subsequent reaction step A.

[0131] Advantageously, the catalyst recovered at the end of the first reaction step A is usable for several successive cycles of reaction step A.

[0132] Flow Process According to one particular embodiment, the present invention relates to a process as defined above, in which at least one of the reaction steps of the process is carried out in continuous flow and in which the catalyst is a heterogeneous Pd-M / support catalyst according to the invention.

[0133] According to one particular embodiment, the present invention relates to a process for producing a process for the preparation of ... - the catalyst is a heterogeneous Pd-M / support catalyst according to the invention installed in a column or cartridge, - or the catalyst is suspended in the reaction mixture, The present invention relates to a process for preparing ethylene glycol as defined above.

[0134] As non-limiting examples, continuous flow processes are carried out in the following types of reactors: - Continuous Stirred Tank Reactor (CSTR), - Flow reactors or tubular reactors - Reactors with fixed or packed beds.

[0135] By way of example, the process according to the invention can be carried out in commercially available flow chemistry equipment such as "H-Cube Pro" or "Phoenix" from ThalesNano INC., 7 Zahony Street, Graphisoft Park, Building D, H-1031 Budapest, Hungary, or "E-Series" or "R-Series flow chemistry systems" from Vapourtec Ltd, Unit 21 / Park Farm Business Centre / Fornham Pk, Bury Saint Edmunds IP28 6TS, United Kingdom.

[0136] Advantageously, the continuous flow process is carried out at a temperature between 25°C and 200°C.

[0137] Advantageously, the continuous flow process is carried out at a pressure between 0.1 MPa and 15 MPa, in particular between 0.1 and 4 MPa.

[0138] The expression "0.1 to 4 MPa" corresponds to the following ranges: 0.1 to 0.5 MPa; 0.5 to 1.0 MPa; 1.0 to 1.5 MPa; 1.5 to 2.0 MPa; 2.0 to 2.5 MPa; 2.5 to 3.0 MPa; 3.0 to 3.5 MPa; 3.5 to 4.0 MPa.

[0139] In one particular embodiment, the continuous flow process is carried out in a reactor where the gas represents 10-90% of the reactor volume.

[0140] The expression "10~90%" corresponds to the following ranges: 10~20%; 20~30%; 30~40%; 40~50%; 50~60%; 60~70%; 70~80%; 80~90%.

[0141] According to one particular embodiment, the continuous flow process is carried out by means that allows a contact time between the reagents of between 1 second and 2 hours, in particular between 1 second and 2 minutes.

[0142] The expression "1 second to 2 hours" corresponds to the following ranges: 1 to 15 seconds; 15 to 30 seconds; 30 seconds to 1 minute; 1 to 2 minutes; 2 to 15 minutes; 15 to 30 minutes; 30 minutes to 1 hour; 1 to 2 hours.

[0143] According to one particular embodiment, the carbonylation reaction step A of the process is carried out in continuous flow and comprises means for introducing into the reactor a flow of CO in contact with the substrate (alcohol) and a flow of oxygen, either separately or as a mixture.

[0144] According to one particular embodiment, the hydrogenation reaction step B of the process is carried out in continuous flow and comprises means for introducing a hydrogen flow in contact with the substrate (oxalate) into a reactor.

[0145] According to a particular embodiment, the carbonylation reaction step A and the hydrogenation reaction step B of the process according to the invention as defined above are carried out in continuous flow and comprise means for introducing into the reactor a gas flow in contact with the substrate.

[0146] According to one particular embodiment, the carbonylation reaction step A and the hydrogenation reaction step B of the process according to the invention as defined above are carried out in the same reactor.

[0147] Catalytic activity The activity of the catalyst according to the invention can be described in terms of the "Number of Catalytic Cycles (NCC)".

[0148] The "number of catalytic cycles (NCC)" is the number of moles of product formed (n prod ) and the number of moles of active catalyst species (n cat )

[0149] For carbonylation reactions, NCC is the number of moles of product formed (n prod ) and the number of moles of palladium in the catalyst (n cat )

[0150] For hydrogenation reactions, NCC is the number of moles of product formed (n prod ) and the number of moles of copper in the catalyst (n cat )

[0151] The NCC is calculated as follows: NCC=n prod / n cat

[0152] Unlike the turnover number (TON), which represents the maximum number of catalytic cycles that a catalyst can achieve before its complete and irreversible degradation, the catalytic cycle number represents the total number of catalytic cycles that a catalyst achieves under given reaction conditions. At the end of the reaction, the catalyst used is not necessarily degraded and therefore can be considered reusable. Thus, NCC is not a measure of the catalyst's lifetime, but rather a measure of the catalyst's productivity under given conditions of catalytic reaction.

[0153] yield Chemical yield displays the efficiency of the chemical reaction being studied. The yield is the ratio between the amount of product obtained and the maximum amount that would be obtained if the reaction were completed.

[0154] The yield of reaction step B for hydrogenating oxalate to ethylene glycol according to the present invention is determined as a percentage of moles of ethylene glycol obtained per mole of oxalate.

[0155] The yield of reaction step B for hydrogenating oxalate to ethylene glycol can be determined using gas chromatography-mass spectrometry (GC-MS) using mesitylene as an internal standard.

[0156] Yield can also be assessed by determining the amount of product after purification to isolate the product.

[0157] According to a particular embodiment, the invention relates to the use as defined above, wherein said hydrogenation reaction step B has a yield of more than 70%, preferably more than 75% and suitably more than 90%.

[0158] Selectivity The selectivity of a chemical reaction defines the amount of desired product formed in relation to the number of moles of a limiting reagent consumed. It indicates whether several reactions occur in parallel and produce undesirable by-products, or whether the reaction taking place is the only reaction consuming a reagent.

[0159] For reaction step B, selectivity is defined as the amount of ethylene glycol obtained relative to the total amount of product obtained, including ethylene glycol and secondary by-products resulting from the conversion of oxalate compounds.

[0160] According to a particular embodiment, the present invention relates to a process as defined above, wherein said process for the preparation of ethylene glycol is selective, the selectivity being greater than 70%, preferably greater than 75% and more preferably greater than 90%.

[0161] The expression "selective preparation process" means a process which makes it possible to obtain the product in question, ethylene glycol, with a selectivity of more than 50%.

[0162] The expression "greater than 70%" corresponds to the following ranges: greater than 70%; greater than 80%; greater than 90%.

[0163] The expression "greater than 75%" corresponds to the following ranges: greater than 75%; greater than 80%; greater than 85%; greater than 90%; greater than 95%.

[0164] The term "greater than 90%" corresponds to the following ranges: greater than 90%; greater than 91%; greater than 92%; greater than 93%; greater than 94%; greater than 95%; greater than 96%; greater than 97%; greater than 98%; greater than 99%.

[0165] According to one particular embodiment, the present invention relates to a process as defined above, in which the first catalytic reaction step A of oxidative carbonylation from an alcohol, carbon monoxide and an oxidant, in particular molecular oxygen, optionally in the presence of a promoter, to form an oxalate compound as a reaction intermediate is selective, with a selectivity of more than 70%, preferably more than 75% and more preferably more than 90%.

[0166] The expression "selective oxidative carbonylation reaction step" means a carbonylation reaction step which makes it possible to obtain the target product, an oxalate compound, with a selectivity of more than 70%.

[0167] According to a particular embodiment, the present invention relates to a process as defined above, in which the second catalytic reaction step B of the hydrogenation of said oxalate compounds with hydrogen to obtain ethylene glycol is selective, with a selectivity of more than 70%, preferably more than 75% and suitably more than 90%.

[0168] The expression "selective hydrogenation reaction step" means a hydrogenation reaction step which makes it possible to obtain the target product, ethylene glycol, with a selectivity of more than 70%.

[0169] According to one particular embodiment, the present invention relates to a process as defined above, in which a first catalytic reaction step A of oxidative carbonylation starting from an alcohol, carbon monoxide and an oxidant, in particular molecular oxygen, optionally in the presence of a promoter, to form an oxalate compound as a reaction intermediate, and a second catalytic reaction step B of hydrogenation of said oxalate compound with hydrogen to obtain ethylene glycol, are selective, the selectivity being greater than 70%, preferably greater than 75%, suitably greater than 90%.

[0170] The expression "selective reaction step" means a reaction step which makes it possible to obtain the target product, an oxalate compound or ethylene glycol, with a selectivity of more than 70%.

[0171] According to one particular embodiment, the present invention provides a method for producing a cellular membrane comprising: ● Reaction step A is ○ - an alcohol selected from methanol or ethanol, - 6.5MPa, carbon monoxide, - 1.5MPa molecular oxygen in detail, - catalysts of the formula Pd-M / support, where M represents Cu or Ag, - tetramethylammonium iodide as a promoter, - triethylamine as a base, acetonitrile as a solvent, to obtain a reaction medium 1, which can be pressurized to 0.1 to 15 MPa, in particular 8.0 MPa; heating the reaction medium, in particular to a temperature of about 90° C., preferably for 16 hours, Obtaining an oxalate compound; Contains; ● Reaction step B is ○- the oxalate compound, - 5.0Mpa, dihydrogen, said catalyst of the formula Pd-M / support, where M represents Cu or Ag, - ethanol as a solvent, to obtain a reaction medium 2, which may be pressurized to between 0.1 and 15 MPa, in particular 5.0 MPa; In particular, the reaction medium is heated to a temperature of about 200° C., preferably for 16 hours, or to a temperature of about 220° C., preferably for 8 hours, obtaining ethylene glycol; Contains It relates to a method as defined above.

[0172] Pd-Cu / ZrO2 catalyst Another object of the present invention is to provide a bimetallic catalyst of palladium and copper on a zirconium dioxide support of the formula Pd-Cu / ZrO2, a palladium content of 0.1 to 10%, in particular 2%, and a copper content of 0.1 to 40%, in particular 10%, in weight percentage relative to the total weight of the catalyst; and ○ 1-50m when measured by BET 2 / g, details are 1-10m 2 / g, preferably 5 to 7 m 2 / g surface area, The present invention relates to a bimetallic catalyst comprising:

[0173] The inventors measured approximately 5 m 2 A bimetallic catalyst of palladium and copper on a zirconium dioxide support with a specific surface area of ​​63 m 2 / g or 81m 2 It was unexpectedly observed that the catalyst with a specific surface area of ​​50 m / g was more efficient than that with a catalyst with a specific surface area of ​​50 m / g. This high efficiency applies to both the carbonylation reaction (step A) and the hydrogenation reaction (step B) for the preparation of ethylene glycol, and in particular allows the hydrogenation reaction to achieve a yield of 92% and a selectivity of 94%, as shown in the results of Example 24. In fact, at 50 m 2 A specific surface area of ​​greater than 1 / g is expected to allow greater accessibility to the substrate, which will favorably affect the yield of the catalyst.

[0174] In one particular embodiment, the present invention provides a method for producing a pharmaceutical composition comprising: a crystalline phase of zirconium dioxide, analyzed by X-ray diffraction, crystallized in monoclinic baddeleyite, comprising a crystallite size of 20 to 100 nm, preferably 20 to 50 nm, and optionally containing hafnium atoms as impurities; The present invention relates to a bimetallic catalyst of palladium and copper on a zirconium dioxide support of the formula Pd-Cu / ZrO2 as defined above, further comprising:

[0175] For the purposes of the present invention, "baddeleyite" refers to natural zirconium oxide of formula ZrO2 containing 0.1%-5% hafnium oxide and crystallizing in the monoclinic system. The properties of baddeleyite, such as its composition and crystallographic structure, in particular the space group with the dimensions of the crystal lattice, are reported and available in the prior art and are known to the skilled person, for example Kudoh, Y. et al., (Phys Chem Minerals 13, 233-237 (1986)) or McCullough J D. et al., (Acta Crystallographica 12 (1959) 507-511).

[0176] In one particular embodiment, the crystalline phase of the zirconium dioxide includes impurities such as hafnium (Hf) atoms.

[0177] 20-100 nm means the following ranges: 20-30 nm; 30-40 nm; 40-50 nm; 50-60 nm; 60-70 nm; 70-80 nm; 80-90 nm; 90-100 nm.

[0178] In another particular embodiment, the present invention provides Two populations of particles, namely: - a first population of particles having a polyhedral type morphology, and - a second population of particles smaller in size than the first population, having a rounded and tangled morphology, the second population having a size between 10 nm and 1 micrometer, said particles forming clusters between 1 and 100 micrometers; The present invention relates to a bimetallic catalyst of palladium and copper on a zirconium dioxide support of the formula Pd-Cu / ZrO2, as defined above, having the form:

[0179] For the purposes of the present invention, "polyhedral type particles" means particles with edges, corners or chamfered edges.

[0180] For the purposes of the present invention, "particles having a rounded morphology" means particles that have no edges, corners or chamfered edges.

[0181] For purposes of the present invention, "entangled particles" means rounded particles that have the appearance of being clumped or fused together and form a visible surface of projections.

[0182] For purposes of the present invention, a "particle cluster" means a set of entangled particles that are in visual or mechanical close contact with one another.

[0183] In one particular embodiment, the present invention provides a method for producing a pharmaceutical composition comprising: Copper atoms in oxidation states (I) and (II), and Palladium atoms in the (II) oxidation state, The present invention relates to a bimetallic catalyst of palladium and copper on a zirconium dioxide support of the formula Pd-Cu / ZrO2 as defined above, further comprising:

[0184] Advantageously, the molar amount of copper atoms in oxidation state (I) is greater than the molar amount of copper atoms in oxidation state (II).

[0185] Pd-Ag / γ-Al2O3 catalyst Another object of the present invention is to provide a bimetallic catalyst of palladium and silver on an alumina support of the formula Pd-Ag / γ-Al2O3: a palladium content of 0.1 to 10%, in particular 2%, and a silver content of 0.1 to 40%, in particular 15%, in percentage by weight relative to the total weight of the catalyst; Silver atoms in the oxidation states (I) and (II) and palladium atoms in the oxidation state (II), Including, It relates to a bimetallic catalyst in the form of a mass of agglomerated, generally spherical particles of 10-100 micrometers in size having a porous morphology with a honeycomb appearance on the surface.

[0186] For the purposes of the present invention, "porous morphology with a honeycomb appearance" means the visible morphology of a series of craters with common edges in the form of ridges.

[0187] Pd-Cu / γ-Al2O3 catalyst Another object of the present invention is a bimetallic catalyst of palladium and copper on an alumina support of the formula Pd-Cu / γ-Al2O3: a palladium content of 0.1 to 10%, in particular 2%, and a copper content of 0.1 to 40%, in particular 10%, in percentage by weight relative to the total weight of the catalyst; copper atoms in the (II) oxidation state and palladium atoms in the (II) oxidation state, Including, The present invention relates to a bimetallic catalyst in the form of a mass of generally spherical and agglomerated particles of 10-100 micrometers in size, having a porous morphology with a honeycomb appearance on the surface.

[0188] Method for preparing the catalyst Another subject of the invention is a process for the preparation of a catalyst containing palladium and a metal M on an oxidic support of the formula Pd-M / support, where M represents Cu or Ag, comprising: ● impregnating a palladium salt and a copper or silver salt dissolved in an aqueous solution, in particular in a volume of 5-10 mL of water, on an oxide support in powder form, in a ratio of solution mass / support mass of 0.6-1.0; Step C to obtain a Pd-M / support catalyst in the form of a homogeneous material, In detail; - the use of a palladium salt concentration calculated to obtain a palladium content of 0.1 to 10% by weight relative to the total weight of the catalyst; - the use of copper or silver salt concentrations calculated to obtain a copper or silver content of 0.1 to 40% by weight based on the total weight of the catalyst; and step C including step D of drying said homogeneous material at a temperature in particular between 60 and 100° C., in particular at 80° C., preferably for a period of 10 to 24 hours, in particular for 16 hours, to obtain the Pd-M / support catalyst in the form of an anhydrous homogeneous material; ● an activation step E, comprising the calcination of said anhydrous homogeneous material, in particular at a temperature between 200 and 1000°C, in particular at 600°C, preferably for a period of 1 to 15 hours, in particular 2 hours, to obtain said catalyst; The present invention relates to a preparation method comprising the steps of:

[0189] Advantageously, the palladium salt is palladium nitrate and the copper or silver salt is copper nitrate or silver nitrate.

[0190] The inventors have surprisingly discovered that the preparation method makes it possible to obtain active and efficient catalysts for the two reactions in the ethylene glycol preparation process: carbonylation of alcohols to oxalates and hydrogenation of oxalates to ethylene glycol, without the need for a preliminary step of reducing the metal atoms Pd, Cu or Ag under hydrogen flow.

[0191] In one particular embodiment, the present invention relates to a method for preparing a Pd-Cu / ZrO2 catalyst according to the catalyst of the invention as defined above, comprising: ● impregnating palladium and copper salts dissolved in aqueous solution, in particular palladium nitrate and copper nitrate, in a volume of 5-10 mL of water, on a zirconium dioxide support, in particular in powder form, in a solution mass / support mass ratio of 0.6-1.0; Step C of obtaining a Pd-Cu / ZrO2 catalyst in the form of a homogeneous material, In detail; - the use of a palladium salt concentration calculated to obtain a palladium content of 0.1 to 10% by weight relative to the total weight of the catalyst; - the use of a copper salt concentration calculated to obtain a copper content of 0.1 to 40% by weight relative to the total weight of the catalyst; and step C including D. drying said homogeneous material at a temperature, in particular between 60 and 100° C., in particular at 80° C., for a period of time preferably between 10 and 24 hours, in particular 16 hours, to obtain Pd—Cu / ZrO2 in the form of an anhydrous homogeneous material; ● an activation step E, comprising the calcination of said anhydrous homogeneous material, in particular at a temperature between 200 and 1000°C, in particular at 600°C, preferably for a period of 1 to 15 hours, in particular 2 hours, to obtain said catalyst; The present invention relates to a preparation method comprising the steps of:

[0192] Advantageously, the support used to prepare the catalyst has a thickness of 1 to 50 m 2 / g, details are 1~10cm 2 / g, preferably 5 to 7 m 2 / g.

[0193] Advantageously, the support used to prepare the catalyst is zirconium dioxide crystallized in monoclinic baddeleyite, with a crystallite size of between 20 and 100 nm, preferably between 20 and 50 μm, and a crystallite size of between 1 and 50 nm. 2 / g, details are 1-10m 2 / g, preferably 5 to 7 m 2 / g and optionally containing hafnium atoms as an impurity.

[0194] In one particular embodiment, the present invention provides a method for preparing a Pd-Ag / γ-Al2O3 catalyst, comprising: ● by impregnation of palladium and silver salts dissolved in aqueous solution, in particular palladium nitrate and copper nitrate, on an alumina support (γ-Al2O3), in particular in powder form, in a volume of 5-10 mL of water, in a ratio of solution mass / support mass of 0.6-1.0; Step C to obtain a Pd-Ag / γ-Al2O3 catalyst in the form of a homogeneous material, In detail; - the use of a palladium salt concentration calculated to obtain a palladium content of 0.1 to 10% by weight relative to the total weight of the catalyst; - the use of a silver salt concentration calculated to obtain a silver content of 0.1 to 40% by weight relative to the total weight of the catalyst; and step C including D) drying said homogeneous material at a temperature, in particular between 60 and 100°C, in particular at 80°C, for a period of time preferably between 10 and 24 hours, in particular 16 hours, to obtain Pd-Ag / γ-Al2O3 in the form of an anhydrous homogeneous material; ● an activation step E, comprising the calcination of said anhydrous homogeneous material, in particular at a temperature between 200 and 1000°C, in particular at 600°C, preferably for a period of 1 to 15 hours, in particular 2 hours, to obtain said catalyst; The present invention relates to a preparation method comprising the steps of:

[0195] Pd-M catalysts / supports prepared according to the present invention Another subject of the invention relates to a supported bimetallic catalyst of the formula Pd-M / support, comprising palladium and the metal M on a support, where M represents Cu or Ag, obtainable by a process for preparing a catalyst as defined above.

[0196] Pd-Cu / ZrO2 catalyst prepared according to the present invention In one particular embodiment, the present invention relates to a bimetallic catalyst of palladium and copper on a zirconium dioxide support of formula Pd-Cu / ZrO2 obtainable by the process for preparing the catalyst as defined above.

[0197] According to one embodiment, the present invention comprises: ● impregnating palladium and copper salts dissolved in aqueous solution, in particular palladium nitrate and copper nitrate, in a volume of 5-10 mL of water, on a zirconium dioxide support, in particular in powder form, in a solution mass / support mass ratio of 0.6-1.0; Step C of obtaining a Pd-Cu / ZrO2 catalyst in the form of a homogeneous material, In detail; - the use of a palladium salt concentration calculated to obtain a palladium content of 0.1 to 10% by weight relative to the total weight of the catalyst; - the use of a copper salt concentration calculated to obtain a copper content of 0.1 to 40% by weight relative to the total weight of the catalyst; and step C including D. drying said homogeneous material at a temperature, in particular between 60 and 100° C., in particular at 80° C., for a period of time preferably between 10 and 24 hours, in particular 16 hours, to obtain Pd—Cu / ZrO2 in the form of an anhydrous homogeneous material; ● an activation step E, comprising the calcination of said anhydrous homogeneous material, in particular at a temperature between 200 and 1000°C, in particular at 600°C, preferably for a period of 1 to 15 hours, in particular 2 hours, to obtain said catalyst; The present invention relates to a bimetallic catalyst of palladium and copper on a zirconium dioxide support of the formula Pd-Cu / ZrO2, which can be obtained by a preparation process comprising the steps of:

[0198] In one particular embodiment, the present invention relates to a bimetallic catalyst of palladium and silver on an alumina support (γ-Al2O3) of formula Pd-Ag / γ-Al2O3, obtainable by the process for preparing the catalyst as defined above.

[0199] Another object of the present invention is a bimetallic catalyst of palladium and copper on a zirconium dioxide support of the formula Pd-Cu / ZrO2: a palladium content of 0.1 to 10%, in particular 2%, and a copper content of 0.1 to 40%, in particular 10%, in weight percentages relative to the total weight of the catalyst; - the catalyst has an X-ray photoelectron spectroscopy spectrum similar to that shown in FIG. 1 for a composition of 2% Pd and 10% Cu, in weight percent relative to the total weight of the catalyst; - the catalyst has a morphological appearance by scanning microscopy similar to that shown in FIG. 2 for a composition of 2% Pd and 10% Cu in weight percent relative to the total weight of the catalyst; Concerning bimetallic catalysts.

[0200] The following examples and figures illustrate the invention without limiting its scope. [Brief description of the drawings]

[0201] [Figure 1] FIG. 1 shows the X-ray photoelectron spectroscopy spectrum of a Pd-Cu / ZrO2 catalyst with a composition of 2% Pd and 10% Cu by weight relative to the total weight of the catalyst, prepared using a zirconium dioxide support with a specific surface area of ​​5-7 m2 / g. [Diagram 2] Two scanning electron microscopy images of Pd-Cu / ZrO2 catalysts with a composition of 2% Pd and 10% Cu by weight relative to the total weight of the catalyst, prepared using a zirconium dioxide support with a specific surface area of ​​5-7 m2 / g, are shown. [Diagram 3] The diffraction patterns of Pd(2%)Cu(10%) / ZrO2 catalysts prepared using zirconium dioxide supports with specific surface areas of 5-7 m2 / g are shown. [Figure 4] Diffraction patterns of two catalysts prepared with zirconium dioxide having a specific surface area of ​​more than 85 m2 / g, Pd(2%)Cu(10%) / ZrO2 and Pd(1%)Cu(3%) / ZrO2, are shown. [Diagram 5] SEM images of Pd(2%)Cu(10%) / ZrO2 catalysts prepared using zirconium dioxide with specific surface areas of 5-7 m2 / g are shown. [Figure 6] FIG. 1 shows an SEM image of a Pd(2%)Cu(10%) / ZrO2 catalyst prepared using zirconium dioxide with a specific surface area of ​​more than 85 m2 / g. [Figure 7] SEM image of Pd(2%)Cu(10%) / γ-Al2O3 catalyst. [Figure 8] SEM image of Pd(2%)Ag(15%) / γ-Al2O3 catalyst. [Figure 9] 1 shows the XPS spectrum of the Pd(2%) / ZrO2 catalyst. [Figure 10] The XPS spectrum of the Pd(2%)Cu(10%) / γ-Al2O3 catalyst is shown. [Figure 11] The XPS spectrum of the Pd(2%)Ag(15%) / γ-Al2O3 catalyst is shown. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0202] [Example] Example 1: Materials and Methods 5~7m 2The ZrO2 support with a specific surface area of ​​1000 nm / g is supplied by Sterm Chemicals, 15 Rue de l'Atome, 67800 Bischheim (product number 93-4013). The supports designated ZrO2 below are supplied by Sterm Chemicals without further clarification.

[0203] 85m 2 A ZrO2 support (monoclinic phase) with a specific surface area of ​​more than 1000 nm / g is supplied by Alfa Aesar (Thermo Fisher Scientific) under the product number AA4381522.

[0204] The γ-Al2O3 support is supplied by Sterm Chemicals, 15 Rue de l'Atome, 67800 Bischheim, reference number 13-2525.

[0205] The SiO2 support (40-63 μm) was supplied by VWR chemicals under reference number 151125P.

[0206] Palladium nitrate (Pd(NO3)2·xH2O) and other metal salts such as Cu(NO3)2·3H2O and AgNO3 were supplied by Fischer.

[0207] The 450 mL and 1 L autoclaves are supplied by Parr Instrument Company.

[0208] Example 2: General procedure for the preparation of heterogeneous Pd / ZrO2 catalysts A solution was formed by dissolving Pd(NO3)2·xH2O in a minimum volume of 5-10 mL of demineralized water. This solution containing the metal precursor was added to an appropriate amount of zirconium dioxide support, and the resulting ZrO2 paste was mixed at room temperature until a homogeneous material was obtained. The material was then dried at 80 °C for 16 h and calcined at 600 °C for 2 h to obtain the catalyst.

[0209] Example 3: General procedure for the preparation of heterogeneous Cu / ZrO2 catalysts A solution was formed by dissolving Cu(NO3)2·3H2O in a minimum volume of 5-10 mL of demineralized water. This solution containing the metal precursors was added to an appropriate amount of zirconium dioxide support, and the resulting ZrO2 paste was mixed at room temperature until a homogeneous material was obtained. The material was then dried at 80 °C for 16 h and calcined at 600 °C for 2 h to obtain the catalyst.

[0210] Example 4: General procedure for the preparation of heterogeneous Pd-Cu / ZrO2 catalysts A solution was formed by dissolving Pd(NO3)2·xH2O and Cu(NO3)2·3H2O in a minimum volume of 5-10 mL of demineralized water. This solution containing the metal precursors was added to an appropriate amount of zirconium dioxide support, and the resulting ZrO2 paste was mixed at room temperature until a homogeneous material was obtained. The material was then dried at 80 °C for 16 h and calcined at 600 °C for 2 h to obtain the catalyst.

[0211] Example 5: Preparation of heterogeneous monometallic and bimetallic Pd / ZrO2, Cu / ZrO2, Pd-Cu / ZrO2 catalysts Table 1 below reports the preparation conditions for Pd / ZrO2, Cu / ZrO2 and Pd-Cu / ZrO2 catalysts prepared according to Examples 2, 3 and 4.

[0212] [Table 1]

[0213] Example 6: General procedure for the preparation of heterogeneous Pd-Cu / γ-Al2O3 catalysts A solution was formed by dissolving Pd(NO3)2·xH2O and Cu(NO3)2·3H2O in a minimum volume of 5-10 mL of demineralized water. This solution containing the metal precursors was added to an appropriate amount of γ-Al2O3 support, and the resulting paste was mixed at room temperature until a homogeneous material was obtained. The material was then dried at 80 °C for 16 h and calcined at 600 °C for 2 h to obtain the catalyst.

[0214] Example 7: Preparation of heterogeneous bimetallic Pd-Cu / γ-Al2O3 catalyst Table 2 below reports the conditions for preparing the Pd-Cu / γ-Al2O3 catalyst prepared according to Example 6.

[0215] [Table 2]

[0216] Example 8: General procedure for the preparation of heterogeneous Ag / γ-Al2O3 catalysts AgNO3 was dissolved in a minimum volume of 5-10 mL of demineralized water to form a solution. This solution containing the metal precursors was added to an appropriate amount of γ-Al2O3 support and the resulting paste was mixed at room temperature until a homogenous material was obtained. The material was then dried at 80°C for 16 hours and calcined at 600°C for 2 hours to obtain the catalyst.

[0217] Example 9: General procedure for the preparation of heterogeneous Pd-Ag / γ-Al2O3 catalysts A solution was formed by dissolving Pd(NO3)2·xH2O and AgNO3 in a minimum volume of 5-10 mL of demineralized water. This solution containing the metal precursors was added to an appropriate amount of the support γ-Al2O3, and the resulting paste was mixed at room temperature until a homogeneous material was obtained. The material was then dried at 80 °C for 16 h and calcined at 600 °C for 2 h to obtain the catalyst.

[0218] Table 3 below reports the preparation conditions for the Ag / γ-Al2O3 and Pd-Ag / γ-Al2O3 catalysts prepared according to Examples 8 and 9.

[0219] [Table 3]

[0220] Example 10: General procedure for the preparation of heterogeneous Pd-Ag / SiO2 catalysts A solution was formed by dissolving Pd(NO3)2·xH2O and AgNO3 in a minimum volume of 5-10 mL of demineralized water. This solution containing the metal precursors was added to an appropriate amount of SiO2 support, and the resulting paste was mixed at room temperature until a homogeneous material was obtained. The material was then dried at 80 °C for 16 h and calcined at 600 °C for 2 h to obtain the catalyst.

[0221] Table 4 below reports the conditions for preparing the Pd-Ag / SiO2 catalyst prepared according to Example 10.

[0222] [Table 4]

[0223] Example 11: General heterogeneous catalytic procedure for the oxidative carbonylation of methanol to oxalate In a 450 mL Parr autoclave equipped with a magnetic stirrer, the heterogeneous palladium catalyst (0.24 mmol Pd), tetrabutylammonium iodide TBAI (554 mg, 1.5 mmol) as promoter, triethylamine Et3N (0.14 mL, 1.0 mmol), acetonitrile (50 mL) and methanol (25 mL) were introduced. The reactor was sealed and the reaction mixture was purged three times with nitrogen (5 bar) and twice with oxygen (5 bar).

[0224] The autoclave was then pressurized with 15 bar of oxygen and a further 65 bar of carbon monoxide (total pressure 80 bar). The reaction medium was then stirred at 90° C. for 16 hours.

[0225] Once the reaction was complete, the autoclave was brought to room temperature, then depressurized and purged with nitrogen (5 bar) three times.

[0226] The final mixture was then filtered and transferred to a 250 mL flask.

[0227] The reaction solvent and excess alcohol were separated by evaporation on a rotary evaporator.

[0228] After purification by recrystallization in diethyl ether, dimethyl oxalate was recovered and the isolated yield was calculated.

[0229] Results are given in the NCC for reactions in which alcohols are used as substrates in the presence of a solvent, and also for reactions carried out in the absence of a solvent, in which the alcohol serves as both substrate and solvent, with the aim of assessing the catalytic efficiency, especially with the use of an excess of alcohol as substrate.

[0230] The NCC is calculated as follows: NCC = moles of product formed / moles of Pd.

[0231] Example 12: General heterogeneous catalytic procedure for the oxidative carbonylation of ethanol to oxalate In a 450 mL Parr autoclave equipped with a magnetic stirrer, the heterogeneous palladium catalyst (0.24 mmol Pd), tetrabutylammonium iodide TBAI (1.5-3.6 mmol), triethylamine Et3N (1.0-4.75 mmol), optionally acetonitrile MeCN (0-50 mL) and ethanol (25-75 mL) as solvents were introduced. The reactor was sealed and the reaction mixture was purged three times with nitrogen (5 bar) and twice with oxygen (5 bar).

[0232] The autoclave was then pressurized with 15 bar of oxygen and a further 65 bar of carbon monoxide (total pressure 80 bar). The reaction medium was then stirred at 90° C. for 16 hours.

[0233] Once the reaction was complete, the autoclave was brought to room temperature, then depressurized and purged with nitrogen (5 bar) three times.

[0234] The final mixture was then filtered and transferred to a 250 mL flask.

[0235] The reaction solvent and excess alcohol were separated by evaporation on a rotary evaporator.

[0236] After purification by vacuum distillation at 120°C / 50-20 mbar, diethyl oxalate was recovered and the isolated yield was calculated.

[0237] Example 13: General heterogeneous catalytic procedure for the hydrogenation of dialkyl oxalates In a 450 mL Parr autoclave equipped with a magnetic stirrer, a heterogeneous copper or silver catalyst (4 mmol of Cu or Ag), a dialkyl oxalate (20 mmol) and ethanol (50 mL) were introduced. The reactor was sealed and the reaction mixture was purged three times with nitrogen (5 bar) and twice with hydrogen (5 bar).

[0238] The autoclave was then pressurized with 50 bar of hydrogen. The reaction medium was then stirred at 200° C. for 16 hours or at 220° C. for 8 hours.

[0239] Once the reaction was complete, the autoclave was brought to room temperature, then depressurized and purged with nitrogen (5 bar) three times.

[0240] The final mixture obtained was diluted in ethanol or methanol, after which the yield was calculated by adding an internal standard (mesitylene) and using GC-MS.

[0241] Example 14: Tests carried out with Pd / ZrO2 catalyst Tables 5 and 6 below report the test conditions for oxidative carbonylation (reaction step A) and hydrogenation (reaction step B), respectively, using a Pd / ZrO2 catalyst.

[0242] Reaction Step A: Carbonylation

[0243] [Table 5]

[0244] Reaction Step B: Hydrogenation

[0245] [Table 6]

[0246] Example 15: Tests carried out with Cu / ZrO2 catalyst Tables 7 and 8 below report the test conditions for oxidative carbonylation (reaction step A) and hydrogenation (reaction step B), respectively, using a Cu / ZrO2 catalyst.

[0247] Reaction Step A: Carbonylation

[0248] [Table 7]

[0249] Reaction Step B: Hydrogenation

[0250] [Table 8]

[0251] Example 16: Tests carried out with Ag / γ-Al2O3 catalyst Tables 9 and 10 below report the test conditions for oxidative carbonylation (reaction step A) and hydrogenation (reaction step B), respectively, using Ag / γ-Al2O3 catalyst.

[0252] Reaction Step A: Carbonylation

[0253] [Table 9]

[0254] Reaction Step B: Hydrogenation

[0255] [Table 10]

[0256] Example 17: Tests carried out with Pd-Cu / oxide catalyst Tables 11 and 12 below report the test conditions for oxidative carbonylation (reaction step A) and hydrogenation (reaction step B) using Pd-Cu catalysts on ZrO2 and γ-Al2O3 supports, respectively.

[0257] Reaction Step A: Carbonylation

[0258] [Table 11]

[0259] Reaction Step B: Hydrogenation

[0260] [Table 12]

[0261] Example 18: Tests carried out with Pd-Ag / γ-Al2O3 or SiO2 catalysts Tables 13 and 14 below report the test conditions for oxidative carbonylation (reaction step A) and hydrogenation (reaction step B) using Pd-Ag / γ-Al2O3 or SiO2 catalysts, respectively.

[0262] Reaction Step A: Carbonylation

[0263] [Table 13]

[0264] Reaction Step B: Hydrogenation

[0265] [Table 14]

[0266] Example 19: General catalyst recycling procedure after hydrogenation of dialkyl oxalates After one hydrogenation reaction of dialkyl oxalates, the catalyst (Cu or Ag) is separated from the liquid reaction medium by filtration. The catalyst is then washed with 3 × 25 mL of ethanol. The material is then dried at 80 °C for 4 h before being used again in the hydrogenation reaction of dialkyl oxalates.

[0267] Example 20 - Catalyst recycle test after hydrogenation of dialkyl oxalate Tables 15 and 16 below report the test conditions and recycle results, respectively, for the hydrogenation (reaction step B) according to Example 19.

[0268] [Table 15]

[0269] [Table 16]

[0270] Example 21: Optimization of the carbonylation reaction using PdCu / ZrO2 Table 17 below reports the results of oxidative carbonylation tests (reaction step A) with variation of the conditions (nature of base, additive, O / CO pressure, reaction time, amount of catalyst and substrate) compared with the general procedure according to Example 12 using a Pd(2%)Cu(10%) / ZrO catalyst prepared according to Example 5.

[0271] Carbonylation yields were calculated using GC-MS, with chlorobenzene used as the internal standard.

[0272] [Table 17]

[0273] Example 22: Volume Optimization The tests were carried out in a 1 liter reactor.

[0274] Test A-7-2 In a 1 L Parr autoclave equipped with a magnetic stirrer, the palladium-based heterogeneous catalyst Pd(2%)Cu(10%) / ZrO2 (0.54 mmol Pd), NaI (0.252 g, 1.68 mmol), triethylamine (0.630 mL, 4.5 mmol) and ethanol (225 mL) were introduced. The reactor was sealed and the reaction mixture was purged three times with nitrogen (5 bar) and twice with oxygen (5 bar). The autoclave was then pressurized with 15 bar oxygen and an additional 65 bar carbon monoxide (total pressure 80 bar). The reaction mixture was then stirred at 90° C. for 16 h.

[0275] Once the reaction was complete, the autoclave was allowed to return to room temperature, then depressurized and purged with nitrogen (5 bar) three times. The reaction mixture was then filtered and the collected solution was transferred to a 500 mL flask. The reaction solvent and excess alcohol were separated by evaporation on a rotary evaporator. The oxalates were recovered after purification (vacuum distillation at 120 °C / 50-20 mbar for diethyl oxalate) and the isolated yield was calculated.

[0276] Tests A7-1 and A7-3 were carried out by varying the concentrations of catalyst, base, additive or substrate (ethanol) compared to the preparation conditions for test A7-2 described above.

[0277] Table 18 below reports the conditions and results of oxidative carbonylation tests (reaction step A) in a 1 liter Parr autoclave using a Pd(2%)Cu(10%) / ZrO2 catalyst prepared according to Example 5.

[0278] [Table 18]

[0279] Example 23: Effect of support and preparation of PdCu / ZrO2 catalyst To determine the influence of the ZrO2 support and catalyst preparation, another zirconium dioxide support consisting of the monoclinic crystalline phase, ZrO2, hereafter referred to as ZrO2 (monoclinic phase), marketed by Alpha Aesar, was used to produce Cat B and Cat C catalysts.

[0280] The ZrO2 support (monoclinic phase) is the same as that used by Yuqing et al. (Chinese Journal of Catalysis, 36, 2015, 1552-1559).

[0281] CatalystCat A A Pd(2%)Cu(10%) / ZrO2 catalyst, hereafter referred to as Cat A, prepared according to Example 5, was compared with Cat B and Cat C catalysts of the same nature but using supports with different properties or different preparation methods.

[0282] Catalyst Cat B: Effect of the support 85m 2 Pd(2%)Cu(10%) / ZrO2 (monoclinic phase), hereafter referred to as Cat B, was prepared according to Example 5 using a ZrO2 support (monoclinic phase) supplied by Alfa Aesar (Thermo Fisher Scientific) under product number 43815, having a specific surface area greater than 1000 nm / g.

[0283] Catalyst Cat C: Influence of preparation According to what is described by Yuqing Jia et al. (Chinese Journal of Catalysis, 36, 2015, pp. 1552-1559), i.e. - a first impregnation step with palladium salts followed by calcination at 350°C in air, - a second impregnation step with a copper salt followed by calcination at 350°C in air, In two successive steps, a Pd(1%)Cu(3%) / ZrO2 catalyst (monoclinic phase), hereafter referred to as Cat C, was prepared using a ZrO2 support (monoclinic phase) supplied by Alfa Aesar.

[0284] Unlike Yuqing Jia et al., the final reduction step was not carried out under hydrogen flow.

[0285] Example 24 Tables 19 and 20 below show the conditions and yield results for oxidative carbonylation (reaction step A) and hydrogenation (reaction step B) tests using Cat A, Cat B and Cat C catalysts, respectively.

[0286] [Table 19]

[0287] [Table 20]

[0288] These results show higher yields for the carbonylation of ethanol to diethyl oxalate (Step A) with a yield of 5.7 g and hydrogenation of the oxalate to ethylene glycol (Step B) with a yield of 92% for the catalyst CAT A of the present invention, with a selectivity of 94%.

[0289] Cat B and Cat C catalysts prepared with ZrO2 support from Alfa Aesar are equally inefficient in terms of yield for both the carbonylation and hydrogenation steps, with yields of 61% and 37%, and selectivities of 70% and 35%, respectively. In particular, Cat C catalyst prepared according to Yuqing Jia et al. is the least efficient in terms of carbonylation yield (step A) and in particular hydrogenation yield and selectivity (step B), which are 2.5 times lower than those of Cat A.

[0290] Example 24: Analysis of PdCu / ZrO2 catalyst - specific surface area The specific surface areas of Cat A, Cat B and Cat C catalysts were measured by BET and the results are shown in Table 21 below.

[0291] [Table 21]

[0292] Example 25: Structural analysis of PdCu / ZrO2 catalyst a) Structure-topology analysis X-ray powder diffractograms of Cat A, Cat B and Cat C catalysts were performed using a Rigaku MINIFLEX II diffractometer emitting X-rays (wavelength Kα 1.54 Å) through a tube and copper source.

[0293] Figures 3 and 4 represent the X-ray diffractograms obtained for the Cat A, Cat B and Cat C catalysts, respectively.

[0294] The results of the analysis of the various diffractograms obtained for Cat A, Cat B and Cat C catalysts are presented below in Tables 22, 23 and 24, respectively.

[0295] [Table 22]

[0296] [Table 23]

[0297] [Table 24]

[0298] The diffractogram shows the presence of a crystallized phase.

[0299] XRD analysis shows the presence of the same crystalline baddeleyite phase (ZrO2) in all three catalysts along with the presence of palladium oxide phase. In the case of Cat A and Cat B catalysts, copper monoxide and palladium phases in metallic state are observed.

[0300] The diffraction peaks of the Cat A and Cat B catalysts can be distinguished from those of the baddeleyite phase of the support. The Cat A peaks are narrower than the Cat B peaks.

[0301] b) Structure-crystallinity Crystallite Size The crystallinity of a material is characterized by the size of the crystallites.

[0302] To compare the different ZrO2 supports of Cat A and Cat B catalysts, the crystallite sizes were qualitatively estimated. As a reminder, Cat B and Cat C catalysts were prepared using the same ZrO2 support commercially available from Alfa Aesar, used in Yuqing Jia et al., (Chinese Journal of Catalysis, 36, 2015, 1552-1559).

[0303] The crystallite size was estimated using the Scherrer equation: t=k λ / H cosθ t = crystallite size k=correction factor=0.89 λ = wavelength of the source H = half-width of the peak (in radians) θ=diffraction angle

[0304] The half-width was estimated using Image J processing software (developed by the National Institutes of Health).

[0305] Calculations of crystallite sizes from the Cat A and Cat B diffractograms are shown in Table 25 below.

[0306] [Table 25]

[0307] The support used in Yuqing Jia et al. has a pore volume of 0.27 cc / g and a specific surface area of ​​85 m 2 / g (BET) is a commercially available ZrO2 oxide powder from Alfa Aesar.

[0308] Low values ​​of size, specifically values ​​below 10 nanometers, indicate a structure with low crystallinity. The smaller the crystallites, the broader the diffraction peaks. This effect becomes visible for crystallites with a diameter of less than 1 μm.

[0309] The results show that the catalysts prepared with Sterm's ZrO2 support and Alfa Aesar's ZrO2 support have crystallite sizes of 31 nm and 9 nm, respectively. Thus, Cat A and Cat B catalysts are differentiated by the microstructure of the ZrO2 support.

[0310] In addition to the specific surface area related properties, these results show that the Cat A and Cat B catalyst supports are different in terms of their microstructure.

[0311] Thus, as shown in Examples 17, 21 and 24, the catalyst prepared using a ZrO2 support having a crystallite size of about 30 nm used for steps A and B of the preparation of ethylene glycol is more efficient than a PdCu / ZrO2 catalyst prepared using a more polycrystalline, less crystalline ZrO2 support having a crystallite size of about 9 nm.

[0312] Example 26: Morphological and compositional analysis The SEM images in Figures 2, 5, 6, 7 and 8 were taken using a Zeiss MEB-FEG scanning microscope with controlled pressure, which allows the observation of materials with little or no conductivity without any specific preparation.

[0313] It should be noted that samples were stabilized on carbon sticky paper to allow SEM observation, therefore the elemental carbon content can be linked to the use of carbon sticky paper.

[0314] Quantification was performed by EDX spectroscopy on sample areas of the catalyst and the results are expressed as mass percentages.

[0315] The results of the SEM observations and EDX analysis are summarized below.

[0316] [Cat A: Pd(2%)Cu(10%) / ZrO2(Sterm)] SEM images are shown in Figures 2 and 5. Tangled elongated particles with a non-uniform thickness of less than 1 micrometer are visible. These particles form clusters of a few micrometers to 100 micrometers.

[0317] The EDX analysis of one zone of the sample is shown in Table 26. The particles are composed primarily of zirconium (Zr), oxygen (O) and copper (Cu), and to a lesser extent palladium (Pd), hafnium (Hf) and carbon.

[0318] [Table 26]

[0319] [Catalyst: Pd(2%) / ZrO2(Sterm)] SEM observations of the Pd(2%) / ZrO2 catalyst prepared using Sterm's ZrO2 support reveal a morphology similar to that of the Cat A catalyst, i.e., tangled elongated particles of non-uniform thickness less than 1 micrometer forming clusters.

[0320] [Cat B: Pd(2%)Cu(10%) / ZrO2 (monoclinic phase) manufactured by Alfa Aesar] Figure 6 shows an SEM image of Cat B catalyst. The SEM observations reveal the presence of a population of macroscopic particles with polyhedral morphology of hundreds of micrometers, accompanied by smaller particles with spherical morphology of tens of nanometers on the surface.

[0321] The EDX analysis of two zones of the sample is shown in Table 27.

[0322] These particles are composed primarily of copper (Cu), zirconium (Zr), palladium (Pd) and oxygen (O), with small amounts of carbon (C) and trace amounts of hafnium (Hf) and rhenium (Re).

[0323] [Table 27]

[0324] [Cat C: Pd(1%)Cu(3%) / ZrO2 (monoclinic phase) from Alfa Aesar, prepared according to Jia et al.] SEM observations reveal the presence of micrometer and nanometer particles with polyhedral morphology.

[0325] The EDX analysis of one zone of the sample is shown in Table 28.

[0326] These particles are composed primarily of zirconium (Zr), oxygen (O) and copper (Cu), and to a lesser extent carbon (C), hafnium (Hf) and rhenium (Re), along with traces of palladium (Pd).

[0327] [Table 28]

[0328] [Catalyst Pd(2%)Cu(10%) / γ-Al2O3] The SEM image of Pd(2%)Cu(10%) / γ-Al2O3 is shown in Figure 7. The SEM observations reveal the presence of a population of macroscopic particles with an overall spherical morphology, aggregated to a size of tens of micrometers, with a porous honeycomb-like morphology on the surface.

[0329] [Catalyst Pd(2%)Ag(15%) / γ-Al2O3] Figure 8 shows an SEM image of Pd(2%)Ag(15%) / γ-Al2O3. The SEM observations reveal the presence of a population of macroscopic particles with an overall spherical morphology, aggregated to a size of tens of micrometers, with a porous morphology with a honeycomb appearance on the surface. The particles have the same appearance and morphology as Pd(2%)Cu(10%) / γ-Al2O3.

[0330] Example 27: XPS Catalyst Surface Studies The analysis is carried out using a PHI QUANTES photon emission spectrometer. This instrument is equipped with a monochromatic X-ray source (aluminum K α The system is equipped with a chromium X-ray source for Hard XPS, a charge neutralization system for electrically insulating the sample, and a hemispherical electron analyzer.

[0331] XPS analysis was performed on the following: - Cat A: Pd(2%)Cu(10%) / ZrO2(Sterm) (see spectrum in Figure 1) - Pd(2%) / ZrO2 catalyst (Sterm) (see spectrum in Figure 9), - Pd(2%)Cu(10%) / γ-Al2O3 (see spectrum in Figure 10), - Pd(2%)Ag(15%) / γ-Al2O3 (see spectrum in Figure 11).

[0332] [Cat A] Cu2p spectrum Analysis of the XPS spectrum over several zones reveals satellite variations typical of CuO (approximately 940-945 eV), displaying the presence of a mixture of Cu+ and Cu2+.

[0333] The concentration of Cu+ is higher (916.8 eV) because the Auger signal is dominated by this component. Neither on the Cu2p spectrum nor on the Auger spectrum can one detect the presence of metallic Cu. If present, it would be masked by the signal corresponding to Cu+.

[0334] Pd3d spectrum Pd3d is interfered with by the Zr3p signals. Standard ZrO2 powder was measured in order to extract the Zr3p signals, namely Zr3p3 at 332.9 eV and Zr3p1 at 346.61 eV.

[0335] The presence of Pd2+ is confirmed by the corresponding visible Pd3d5 / 2 signal (located at 337.5 eV).

[0336] [Pd(2%) / ZrO2 catalyst (Sterm) (see Figure 9)] Pd3d spectrum The Zr3d spectrum overlaps, at least in energy. The width is slightly larger, but this may be due to non-uniform charging. This binding energy agreement should be seen for Pd3d.

[0337] Pd3d is interfered with by the Zr3p signal. The presence of Pd2+ is confirmed by the visibility of the corresponding Pd3d5 / 2 signal (located at 337 eV).

[0338] [Pd(2%)Cu(10%) / γ-Al2O3 (see spectrum in Figure 10 and Table 29 below)] Cu2p spectrum The Cu2p spectrum indicates the presence of Cu2+ primarily in the oxide and hydroxide forms (based on the appearance of satellites).

[0339] Pd3d spectrum The Pd3d spectra are identical for the two measured zones.

[0340] The Pd3d5 / 2 component is located at 337.5 eV.

[0341] [Table 29]

[0342] [Pd(2%)Ag(15%) / γ-Al2O3 (see spectrum in Figure 11 and Table 30 below)] Ag3d spectrum The Ag3d spectrum was difficult to interpret and required comparison with a reference spectrum (metallic Ag spectrum). Analysis of the Auger signal indicates that it is a mixture of Ag oxides (I and II).

[0343] Pd3d spectrum For the Pd3d spectrum, the energy position is slightly lower at 337.2 eV, with an additional component at lower binding energy, and the Pd3d peak of the sample is broader. Thus, there is a 0.3 eV difference in the position of the Pd5 / 2 peak between the two samples.

[0344] [Table 30]

Claims

1. a first reaction step A of oxidative carbonylation of an alcohol in the presence of a supported bimetallic catalyst of the formula Pd-M / support, comprising palladium and the metal M on a support, where M represents Cu or Ag, to obtain an oxalate compound as a reaction intermediate; a second reaction step B of hydrogenation of the optionally purified oxalate compound produced in reaction step A to ethylene glycol in the presence of a catalyst of the formula Pd-M / support; 1. A method for preparing ethylene glycol, comprising:

2. The process of claim 1 for preparing ethylene glycol from alcohol, comprising the use of a supported bimetallic catalyst of the formula Pd-M / support, the method comprises two reaction steps catalyzed by the same bimetallic catalyst; the first catalytic reaction, Step A, is an oxidative carbonylation from an alcohol, carbon monoxide and an oxidant, particularly molecular oxygen, optionally in the presence of a promoter, to form an oxalate compound as a reaction intermediate; and a second catalytic reaction step B is the hydrogenation of the oxalate compound with hydrogen to obtain ethylene glycol; method.

3. ● Reaction step A is ○ - alcohols, in particular alcohols selected from methanol and ethanol; - carbon monoxide, - oxidizing agents, specifically oxygen O ２ , catalysts of the formula Pd-M / support, where M represents Cu or Ag; optionally a promoter, in particular an iodine compound chosen in particular from among tetramethylammonium iodide, potassium iodide or sodium iodide, preferably tetramethylammonium iodide, optionally a base, in particular triethylamine, optionally a solvent, in particular a solvent chosen from among acetonitrile, tetrahydrofuran, dioxane and toluene, preferably acetonitrile, to obtain a reaction medium 1 which can be pressurized to between 0.1 and 15 MPa; optionally, heating said reaction medium 1 at a temperature between 25 and 200°C, preferably at about 90°C, in particular for a period of between 2 and 24 hours, preferably 16 hours, obtaining an oxalate compound; It contains ● Reaction step B is ○ - the oxalate compound; - dihydrogen, said catalyst of the formula Pd-M / support, where M represents Cu or Ag, optionally a solvent, in particular ethanol, methanol and dioxane, preferably ethanol or methanol, to obtain a reaction medium 2 which can be pressurized to between 0.1 and 15 MPa, in particular to 5 MPa; optionally, heating said reaction medium 2 to a temperature between 100 and 250°C, in particular 200 or 220°C, for a period preferably between 5 and 24 hours, more preferably 8 or 16 hours, obtaining ethylene glycol; Contains, 2. The method for preparing ethylene glycol according to claim 1.

4. ● Reaction step A is ○ - alcohols, in particular alcohols selected from methanol and ethanol; - carbon monoxide, an oxidizing agent, in particular oxygen O 2 , catalysts of the formula Pd-M / support, where M represents Cu or Ag; accelerators, in particular iodine compounds chosen in particular from among tetramethylammonium iodide, potassium iodide or sodium iodide, preferably tetramethylammonium iodide, - a base, in particular triethylamine, a solvent, in particular a solvent chosen from among acetonitrile, tetrahydrofuran, dioxane and toluene, preferably acetonitrile, to obtain a reaction medium 1; heating said reaction medium 1 at a temperature between 25 and 200°C, in particular for a period of between 2 and 24 hours, obtaining an oxalate compound; It contains ● Reaction step B is ○ - the oxalate compound; - dihydrogen, said catalyst of the formula Pd-M / support, where M represents Cu or Ag, solvents, in particular ethanol, methanol and dioxane, preferably ethanol or methanol, to obtain a reaction medium 2; heating said reaction medium 2 to a temperature between 100 and 250°C, preferably for a period of between 5 and 24 hours, obtaining ethylene glycol; Contains, 2. The method for preparing ethylene glycol according to claim 1.

5. ● Reaction step A is ○ - alcohols, in particular alcohols selected from methanol and ethanol; - carbon monoxide, an oxidizing agent, in particular oxygen O 2 , catalysts of the formula Pd-M / support, where M represents Cu or Ag; accelerators, in particular iodine compounds chosen in particular from among tetramethylammonium iodide, potassium iodide or sodium iodide, preferably tetramethylammonium iodide, - a base, in particular triethylamine, a solvent, in particular a solvent chosen from among acetonitrile, tetrahydrofuran, dioxane and toluene, preferably acetonitrile, to obtain a reaction medium 1 pressurized to between 0.1 and 15 MPa; heating said reaction medium 1 at a temperature between 25 and 200°C for a period of between 2 and 24 hours, obtaining an oxalate compound; It contains ● Reaction step B is ○ - the oxalate compound; - dihydrogen, said catalyst of the formula Pd-M / support, where M represents Cu or Ag, solvents, in particular ethanol, methanol and dioxane, preferably ethanol or methanol, to obtain a reaction medium 2 pressurized to between 0.1 and 15 MPa, in particular 5 MPa; heating said reaction medium 2 to a temperature between 100 and 250°C for a time between 5 and 24 hours, obtaining ethylene glycol; Contains, 2. The method for preparing ethylene glycol according to claim 1.

6. ● Reaction step A is ○ - alcohols, in particular alcohols selected from methanol and ethanol; - carbon monoxide, oxygen O 2 , catalysts of the formula Pd-M / support, where M represents Cu or Ag; a promoter selected from among tetramethylammonium iodide, potassium iodide or sodium iodide, preferably tetramethylammonium iodide, to obtain a reaction medium 1 pressurized to between 0.1 and 15 MPa; heating said reaction medium 1 at a temperature between 25 and 200°C for a period of between 2 and 24 hours, obtaining an oxalate compound; It contains ● Reaction step B is ○ - the oxalate compound; - dihydrogen, said catalyst of the formula Pd-M / support, where M represents Cu or Ag, solvents, in particular ethanol, methanol and dioxane, preferably ethanol or methanol, to obtain a reaction medium 2 pressurized to between 0.1 and 15 MPa, in particular 5 MPa; heating said reaction medium 2 to a temperature between 100 and 250°C for a time between 5 and 24 hours, obtaining ethylene glycol; Contains, 2. The method for preparing ethylene glycol according to claim 1.

7. ● Reaction step A is ○ - alcohols, in particular alcohols selected from methanol and ethanol; - carbon monoxide, oxygen O 2 , catalysts of the formula Pd-M / support, where M represents Cu or Ag; - accelerators, - a base, in particular triethylamine, a solvent chosen from among acetonitrile, tetrahydrofuran, dioxane and toluene, preferably acetonitrile, to obtain a reaction medium 1 pressurized to between 0.1 and 15 MPa; heating said reaction medium 1 at a temperature between 25 and 200°C for a period of between 2 and 24 hours, obtaining an oxalate compound; It contains ● Reaction step B is ○ - the oxalate compound; - dihydrogen, said catalyst of the formula Pd-M / support, where M represents Cu or Ag, a solvent selected from ethanol, methanol and dioxane, to obtain a reaction medium 2 pressurized to between 0.1 and 15 MPa, in particular 5 MPa; heating said reaction medium 2 to a temperature between 100 and 250°C for a time between 5 and 24 hours, obtaining ethylene glycol; Contains, 2. The method for preparing ethylene glycol according to claim 1.

8. ● Reaction step A is ○ - alcohols, in particular alcohols selected from methanol and ethanol; - carbon monoxide, oxygen O 2 , catalysts of the formula Pd-M / support, where M represents Cu or Ag; - accelerators, - a base, in particular triethylamine, to obtain a reaction medium 1 pressurized to between 0.1 and 15 MPa; heating said reaction medium 1 at a temperature between 25 and 200°C for a period of between 2 and 24 hours, obtaining an oxalate compound; It contains ● Reaction step B is ○ - the oxalate compound; - dihydrogen, said catalyst of the formula Pd-M / support, where M represents Cu or Ag, a solvent selected from ethanol, methanol and dioxane, to obtain a reaction medium 2 pressurized to between 0.1 and 15 MPa, in particular 5 MPa; heating said reaction medium 2 to a temperature between 100 and 250°C for a time between 5 and 24 hours, obtaining ethylene glycol; Contains, 2. The method for preparing ethylene glycol according to claim 1.

9. ● Reaction step A is ○ - alcohols, in particular alcohols selected from methanol and ethanol; - carbon monoxide, oxygen O 2 , catalysts of the formula Pd-M / support, where M represents Cu or Ag; - accelerators, a base selected from among triethylamine (Et 3 N), 2,6-lutidine, cesium carbonate (Cs 2 CO 3 ) or 1-methylimidazole, in particular triethylamine; a solvent chosen from among acetonitrile, tetrahydrofuran, dioxane and toluene, preferably acetonitrile, to obtain a reaction medium 1 pressurized to between 0.1 and 15 MPa; heating said reaction medium 1 at a temperature between 25 and 200°C for a period of between 2 and 24 hours, obtaining an oxalate compound; It contains ● Reaction step B is ○ - the oxalate compound; - dihydrogen, said catalyst of the formula Pd-M / support, where M represents Cu or Ag, a solvent selected from ethanol, methanol and dioxane, to obtain a reaction medium 2 pressurized to between 0.1 and 15 MPa, in particular 5 MPa; heating said reaction medium 2 to a temperature between 100 and 250°C for a time between 5 and 24 hours, obtaining ethylene glycol; Contains, 2. The method for preparing ethylene glycol according to claim 1.

10. Reaction Step A is 【Chemistry 1】 to prepare an oxalate compound of Formula 2 by contacting an alcohol of Formula 1 In the formula, R ａ but, ● C １ ~C ２０ a linear or branched alkyl group of ● C ３ ~C １０ a cycloalkyl group of the formula ● C ５ ~C ２０ an alkylaryl or alkylheteroaryl group of the formula The method of claim 1 , wherein:

11. The method of claim 1, wherein the alcohol in reaction step A is selected from methanol, ethanol, and isopropanol.

12. The catalyst support is zirconium dioxide (ZrO) ２ , alumina Al ２ O ３ , silica SiO ２ , cerium dioxide CeO ２ , titanium dioxide TiO ２ , magnesium oxide MgO, indium oxide In ２ O ３ or an oxide selected from a mixture of these oxides, preferably zirconium dioxide ZrO ２ The method of claim 1, wherein

13. 2. The process according to claim 1, wherein the catalyst has a palladium content of 0.1 to 10%, in particular 2%, and a content of metal M of 0.1 to 40%, in particular 10% or 15%, in weight percentages relative to the total weight of the catalyst.

14. The supported bimetallic catalyst is Pd—Cu / ZrO, which contains palladium and copper on a zirconium dioxide support. ２ The method of claim 1 , wherein the catalyst is a hydroxybenzoate.

15. Pd-Cu / ZrO ２ In a bimetallic catalyst of palladium and copper on a zirconium dioxide support of the formula: a palladium content of 0.1 to 10%, in particular 2%, and a copper content of 0.1 to 40%, in particular 10%, in weight percentages relative to the total weight of the catalyst, and ○ 1 to 50 m when measured by BET ２ / g, specifically 1 to 10 m ２ / g, preferably 5 to 7 m ２ / g surface area, A bimetallic catalyst comprising:

16. a crystalline phase of zirconium dioxide, analyzed by X-ray diffraction, crystallized in monoclinic baddeleyite, comprising a crystallite size of 20 to 100 nm, preferably 20 to 50 nm, optionally containing hafnium atoms as impurity; 16. The catalyst of claim 15, further comprising:

17. The catalyst comprises two populations of particles: a first population of particles having a polyhedral morphology, and a second population of particles smaller in size than the first population and having a rounded and tangled morphology, said second population of particles having a size between 10 nm and 1 micrometer, said particles forming clusters of 1 to 100 micrometers; 16. The catalyst of claim 15 in the form of:

18. copper atoms in oxidation states (I) and (II), and palladium atoms in oxidation state (II), further comprising In particular, the molar amount of copper atoms in oxidation state (I) is greater than the molar amount of copper atoms in oxidation state (II), The catalyst of claim 15.

19. Pd-Cu / ZrO ２ In the method for preparing a catalyst, impregnation of palladium and copper salts dissolved in aqueous solution, in particular palladium nitrate and copper nitrate, on a zirconium dioxide support, in particular in powder form, in a volume of water of 5 to 10 ml, with a solution mass / support mass ratio of between 0.6 and 1.0, Pd—Cu / ZrO in the form of a homogeneous material ２ A step C of obtaining a catalyst, comprising: For more details, the use of a palladium salt concentration calculated to obtain a palladium content of between 0.1 and 10% by weight relative to the total weight of the catalyst; - the use of a copper salt concentration calculated to obtain a copper content of between 0.1 and 40% by weight relative to the total weight of the catalyst; Step C including: drying said homogeneous material, in particular at a temperature of 60-100°C, in particular at 80°C, for a period of preferably 10-24 hours, in particular 16 hours, to obtain Pd-Cu / ZrO in the form of an anhydrous homogeneous material; ２ a step D of obtaining a catalyst; an activation step E comprising the calcination of said anhydrous homogeneous material, in particular at a temperature between 200 and 1000°C, in particular at 600°C, preferably for a period of 1 to 15 hours, in particular 2 hours, with the aim of obtaining said catalyst; A preparation method comprising:

20. Pd-Cu / ZrO obtainable by the method according to claim 19. ２ A bimetallic catalyst of palladium and copper on a zirconium dioxide support of the formula:

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