Heterogeneous bimetallic catalyst, method for producing same and use of same

Abstract

The present invention relates to a new bimetallic supported catalyst comprising copper and cobalt on a zirconium dioxide support, of formula CoCu / ZrO2, to its use in the implementation of a method for the preparation of ethylene glycol from an oxalate compound by a hydrogenation reaction of said oxalate compound by hydrogen (H2) to obtain ethylene glycol, and to its use in the depolymerization of biomass.

Description

[0001] Description

[0002] BIMETALLIC HETEROGENEOUS CATALYST, ITS PREPARATION PROCESS AND ITS USE

[0003] The present invention relates to a novel bimetallic heterogeneous catalyst, its preparation process and its use, in particular for the synthesis of ethylene glycol from the hydrogenation of oxalate.

[0004] Ethylene glycol is an important material in the chemical industry, enabling various applications such as antifreeze or refrigerant, but especially in the production of textile fibers and polyester resins. Ethylene glycol can be used as a monomer in the manufacture of polyester, and in particular PET (Polyethylene terephthalate) in the presence of terephthalic acid. PET is a polymer widely used in the textile industry, which today is mainly produced from petroleum-based products that generate a large quantity of greenhouse gases, including carbon dioxide.

[0005] A classic method of manufacturing ethylene glycol is made from naphtha and is shown schematically below:

[0006] H

[0007] Hydrolyzed naphtha

[0008] H

[0009] Diagram 1: Classic method of manufacturing ethylene glycol

[0010] Recycling carbon dioxide (CO2) is a major challenge in reducing greenhouse gas emissions. Another route for synthesizing ethylene glycol is the hydrogenation of oxalates or oxamides. Oxalates are high-value raw materials in the chemical industry. They are used extensively to produce various dyes, pharmaceuticals, solvents, extraction agents, and various intermediates in the fine chemical industry.

[0011] Thus the consumption of CO2 can be achieved during the synthesis of oxalates, which are precursors for producing ethylene glycol via a hydrogenation reaction catalyzed with transition metals, as homogeneous or heterogeneous catalysts, as shown schematically below: 2ca cat 2 cat 3

[0012] CO t 1

[0013] Diagram: Production of ethylene glycol from COs

[0014] A homogeneous transition metal catalyst is a catalyst that is soluble in the reaction solvent and forms a single phase.

[0015] A heterogeneous transition metal catalyst is a catalyst that is not soluble involving a reaction involving two phases, e.g., liquid-solid.

[0016] A bimetallic supported catalyst consists of a support, on the surface of which are dispersed and immobilized particles of two metals either in the form of oxides of these metals, or in reduced form, or even a mixture of these two forms.

[0017] The support is advantageously an oxide such as alumina or silica.

[0018] It is understood that the bimetallic catalyst of two metals, Metal-1 and Metal-2, comprises on the support, on its surface accessible to the substrates of the catalyzed reaction, species of the two metals, Metal-1 and Metal-2.

[0019] A monometallic supported catalyst therefore consists of a support on which particles of a single metal are dispersed and immobilized, either in the form of oxides, or in reduced form, or even a mixture of these two forms.

[0020] Generally, the hydrogenation reaction of oxalate to ethylene glycol is catalyzed by a catalyst comprising a metal. For example, the hydrogenation step is carried out with a copper-based catalyst.

[0021] In the article by Yuxi Xu et al. (Catal. Sci. Technol, 2022,12 6782) the use of monometallic copper catalysts supported on zirconium dioxide Cu / ZrC>2 for the hydrogenation of oxalates to ethylene glycol is described. The authors studied the effect of the crystalline phases of the support synthesized at different temperatures and relate the catalyst structure to the catalytic properties.

[0022] In the article by Kong et al. (Catalysis Communications, 65, 2015, 46-50) the use of cobalt-based catalysts in the presence of copper as a promoter, supported on zinc oxide CoCu / ZnO for the hydrogenation of oxalates is described. The monometallic Co / ZnO catalyst for the oxalate hydrogenolysis reaction shows selectivity towards the formation of methane (80%) without the formation of ethylene glycol. The presence of copper as a promoter allows the selectivity to be oriented towards the formation of ethylene glycol.

[0023] For many years, there has been a need for a low-cost and environmentally friendly route for the preparation of ethylene glycol.

[0024] Currently, a heterogeneous catalyst is being sought, which is easy to prepare and allows for the efficient synthesis of environmentally friendly ethylene glycol from oxalate, which is easily industrializable and safe.

[0025] Ethylene glycol also represents a model compound for the cleavage by action of hydrogen, namely hydrogenolysis, of the CC and / or C-O bonds of the diol groups - CHOH-CHOH- present in the carbohydrate molecules (polyols) contained in the biomass. Thus, a catalyst allowing the cleavage by hydrogenolysis of the CC and C-O bonds of ethylene glycol would allow a depolymerization of the biomass by cleavage of the CC and / or C-O bonds of the diol groups present in the biomass.

[0026] One of the aims of the invention is to propose a process for preparing ethylene glycol from oxalate by a reaction using a heterogeneous bimetallic catalyst, in particular based on copper and cobalt.

[0027] Another object of the invention is a process for preparing ethylene glycol having efficient yields and significant selectivity.

[0028] Another aim of the invention is the preparation of ethylene glycol without using toxic reagents.

[0029] Another object of the invention is the preparation of ethylene glycol, using recyclable or recycled reagents and an efficient and reusable heterogeneous catalyst.

[0030] Another aim of the invention is to propose a process for the hydrogenolysis of ethylene glycol using a heterogeneous bimetallic catalyst.

[0031] Another aim of the invention is to propose a process for depolymerizing biomass using a heterogeneous bimetallic catalyst.

[0032] Another aim of the invention is to propose a new heterogeneous bimetallic catalyst on a support.

[0033] Another aim of the invention is to provide a heterogeneous catalyst usable in a continuous flow process.

[0034] Another aim of the present invention is to propose a simple, industrializable and optimized preparation process for this catalyst.

[0035] Use A first object of the present invention is the use of a bimetallic supported catalyst of formula CoCu / Support, comprising cobalt and copper on a support, in the implementation of a process for the preparation of ethylene glycol from an oxalate compound by a hydrogenation reaction of said oxalate compound with hydrogen (H2) to obtain ethylene glycol.

[0036] In the present invention the terms "hydrogen" and "dihydrogen" define the same H2 molecule.

[0037] It is understood that the CoCu / Support catalyst is a heterogeneous catalyst, the catalyst being in solid phase and the reactants being in liquid or gaseous form.

[0038] The use of a heterogeneous catalyst has the advantage of facilitating the separation of the catalyst from the other species involved in the reaction, making it easy to recover and reuse the catalyst and limiting contamination of the product with transition metals. The use of a heterogeneous catalyst also has the advantage of allowing the catalyst to be fixed in the reactor in an enclosure such as a cartridge when operating under continuous flow and thus obtaining catalyst-free products at the reactor outlet.

[0039] For the purposes of the present invention, the term "catalyst" or "supported catalyst" means a material consisting of a support on which catalytic sites are located. It is understood that the bimetallic cobalt and copper catalyst comprises a support and atoms of the elements cobalt and copper. The total weight of the catalyst corresponds to the weight of the support and that of the elements cobalt and copper.

[0040] According to a particular embodiment, the invention relates to the use of a bimetallic supported catalyst CoCu / Support, comprising copper and cobalt on a support, in the implementation of a process for preparing ethylene glycol from an oxalate compound by a hydrogenation reaction of said oxalate compound with hydrogen (H2) to obtain ethylene glycol, in which said support is chosen from zirconium dioxide (ZrC>2), a silica (SiC>2) or an alumina (AI2O3), in particular zirconium dioxide (ZrC>2)

[0041] Use with a CoCu / ZrO2 catalyst

[0042] According to a particular embodiment, the invention relates to the use of a bimetallic supported catalyst comprising cobalt and copper on a zirconium dioxide support, of formula CoCu / ZrC>2, in the implementation of a process for preparing ethylene glycol from an oxalate compound by a hydrogenation reaction of said oxalate compound with hydrogen (H2) to obtain ethylene glycol.

[0043] The inventors unexpectedly observed a synergistic effect between copper and cobalt in a heterogeneous bimetallic supported catalyst, which significantly increased the yield and selectivity of the hydrogenation reaction of oxalates to ethylene glycol. Although the monometallic cobalt catalyst on zirconium dioxide is inactive for the hydrogenation reaction of oxalates to ethylene glycol, the tests (see examples 21 and 22) showed that cobalt has a promoting function in CuCo / ZrC>2 catalysts, promoting the yield and selectivity towards ethylene glycol.

[0044] Indeed, they observed a yield of around 12% with a selectivity of 13% by using a monometallic copper catalyst and that monometallic catalysts based on cobalt are inactive. The use of a bimetallic cobalt and copper catalyst on an oxide support according to the invention makes it possible to achieve a yield of 84% and a selectivity of 95%.

[0045] The inventors also observed that a zirconium dioxide support ZrC>2 allowed better results to be obtained compared to other oxide supports such as silica (SiC>2), cerium dioxide (CeC>2) or alumina (Y-AI2O3).

[0046] According to a particular embodiment, the invention relates to the use of a bimetallic supported catalyst comprising cobalt and copper on a zirconium dioxide support, of formula CoCu / ZrC>2, in the implementation of a process for preparing ethylene glycol from an oxalate compound by a hydrogenation reaction of said oxalate compound with hydrogen (H2) to obtain ethylene glycol.

[0047] According to a particular embodiment, the invention relates to the use as defined above, in which said oxalate is chosen from dimethyloxal, diethyloxalate, dibenzyloxalate, diterbutyloxalate, diisopropyloxalate, diphenyloxalate, in particular chosen from dimethyloxal or diethyloxalate, preferably diethyloxalate.

[0048] Advantageously, the oxalates used can be obtained by a carbonylation reaction of an alcohol in the presence of CO and oxygen.

[0049] Advantageously, carbon monoxide CO for the preparation of oxalate comes from the electrolysis of carbon dioxide CO2 into carbon monoxide CO.

[0050] Thus, advantageously, the synthesis of ethylene glycol is carried out from the recovery of CO2 and an alcohol.

[0051] Use with catalyst preparation by soft chemistry

[0052] According to a particular embodiment, the invention relates to the use as defined above, in which said catalyst is prepared by mixing the support in powder form and an aqueous solution of copper and cobalt salts, followed by drying and calcination.

[0053] According to a particular embodiment, the invention relates to the use as defined above, in which said catalyst is prepared by mixing the support in powder form and an aqueous solution of copper and cobalt salts, free of additive or surfactant, in particular free of an ammonia solution, followed by drying of the material obtained and calcination thereof.

[0054] It is understood that the mixing of the support in powder form and an aqueous solution of copper and cobalt salts consists of bringing a solution of cobalt and copper salts into contact with a support and therefore impregnating the support with the cobalt and copper salts, namely the deposition of cobalt and copper atoms on the surface of the support.

[0055] "Drying" means an operation consisting of heating the material in ambient air in a closed enclosure at a temperature of the order of 60 to 100°C for 10 to 24 hours in order to dry the material, namely to eliminate water molecules, namely free water, adsorbed on the surface or interstitial water.

[0056] "Calcination" means an operation consisting of heating the solid material in ambient air in a closed enclosure to a high temperature of the order of 400 to 1000°C in order to activate it or modify the physical characteristics of the support and eliminate the water of constitution and the salts of metallic precursors such as nitrates and acetates. After calcination, the said material is free of water.

[0057] Advantageously, the catalyst used is prepared as follows with a preparation process comprising the following steps:

[0058] • a step A of impregnation of a cobalt salt and a copper salt, dissolved in an aqueous solution, in a volume of water of 5 to 10 mL, on a zirconium dioxide support in powder form, with a mass ratio of the solution / mass of support of from 0.6 to 1.0; to obtain the CoCu / ZrC>2 catalyst in the form of a homogeneous mixture,

[0059] • a step B of drying said homogeneous mixture, to obtain the CoCu / ZrC>2 catalyst in the form of a dry homogeneous mixture,

[0060] • an activation step C, comprising calcination of said dry homogeneous mixture to obtain said catalyst.

[0061] For the purposes of the present invention, the term "homogeneous mixture" means the homogeneous material obtained by mixing an aqueous solution of metal salts with the support in the form of a solid powder, said aqueous solution of metal salts being distributed homogeneously on the surface of the particles constituting the support and in the interstices of said particles.

[0062] By "dry homogeneous mixture" is meant a homogeneous mixture in which the majority of free water molecules, adsorbed on the surface or in the interstices of the support particles, are eliminated, for example by drying at 60 to 100°C, in particular 80°C to obtain a powder. The preparation of the catalyst leads to the formation of the corresponding insoluble metal oxides because the metal salts of the metals such as nitrate, are completely eliminated after the calcination step at 600°C.

[0063] Advantageously, in impregnation step A, said aqueous solution containing the cobalt and copper salts is free of additives and surfactants. In other words, said aqueous impregnation solution consists of a demineralized water solution in which the cobalt and copper salts are dissolved.

[0064] Advantageously, the cobalt salt is cobalt nitrate and the copper salt is copper nitrate.

[0065] The use according to the invention is therefore implemented with a catalyst prepared with an aqueous solution, a green solvent that is safe compared to the organic solvents used in the prior art. Advantageously, additional additives and surfactants in the synthesis of the catalyst are not necessary, which makes it more industrializable at a lower cost.

[0066] A "green solvent" is a non-toxic, biodegradable or agro-sourced substitute solvent that has the same properties as the toxic solvents it replaces.

[0067] Use with a catalyst having a characteristic relating to the specific surface area.

[0068] According to a particular embodiment, the invention relates to the use as defined above, in which said catalyst has a surface area, analyzed by BET, of 1 to 250 m 2 / g.

[0069] The range from 1 to 250 m 2 / g includes the following ranges; from 1 to 25 m 2 / g; from 25 to 50 m 2 / g; from 50 to 75 m 2 / g; from 75 to 100 m 2 / g; from 100 to 125 m 2 / g; from 125 to 150 m 2 / g; from 150 to 175 m 2 / g; from 175 to 200 m 2 / g; from 200 to 225 m 2 / g; from 225 to 250 m 2 / g.

[0070] According to a particular embodiment, the invention relates to the use as defined above, in which said catalyst has a surface area, analyzed by BET, of 1 to 50 m 2 / g.

[0071] The range from 1 to 50 m 2 / g includes the following ranges: from 1 to 10 m 2 / g; from 10 to 20 m 2 / g; from 20 to 30 m 2 / g; from 30 to 40 m 2 / g; from 40 to 50 m 2 / g.

[0072] According to a particular embodiment, the invention relates to the use as defined above, in which said catalyst has a surface area, analyzed by BET, of 1 to 10 m 2 / g, preferably about 5 m 2 / g.

[0073] The range from 1 to 10 m 2 / g includes the following ranges: from 1 to 2 m 2 / g; from 2 to 3 m 2 / g; from 3 to 4m 2 / g; from 4 to 5 m 2 / g; from 5 to 6 m 2 / g; from 6 to 7 m 2 / g; from 7 to 8 m 2 / g; from 8 to 9 m 2 / g, from 9 to 10 m 2 / g, especially about 5 m 2 / g.

[0074] The inventors unexpectedly found that a bimetallic CoCu / ZrC>2 catalyst with a low specific surface area of ​​1 to 50 m 2 / g, especially from 1 to 10 m 2 / g, prepared with a ZrC>2 support having a specific surface area of ​​5 to 7 m 2 / g allowed improved yields and selectivities of the hydrogenation reaction of oxalates to ethylene glycol, compared to a CoCu / ZrC>2 catalyst of the same cobalt and copper content prepared with a ZrC>2 support having a specific surface area greater than 50 m 2 / g, analyzed by BET. Thus unexpectedly a catalyst with a low specific surface area of ​​approximately 5 m 2 / g is more efficient than a catalyst with a specific surface area greater than 50 m 2 / g in terms of yield and selectivity for the hydrogenation reaction of oxalates to ethylene glycol. It would rather be expected that a catalyst with a larger specific surface area would be more favorable in terms of catalysis because it favors exchanges.

[0075] Use with a catalyst having a specific crystal structure

[0076] According to a particular embodiment, the invention relates to the use as defined above, in which said catalyst comprises a crystalline phase, analyzed by X-ray diffraction, crystallized in a monoclinic crystalline system.

[0077] A "monoclinic crystal system" means a system having one of the following point groups as its symmetry point group: 2, m or 2 / m.

[0078] According to a particular embodiment, the invention relates to the use as defined above, in which said crystalline phase represents from 50 to 90% by total weight of the catalyst.

[0079] According to a particular embodiment, the invention relates to the use as defined above, in which said crystalline phase is baddeleyite.

[0080] According to a particular embodiment, the invention relates to the use as defined above, in which the catalyst support is natural zirconium dioxide (ZrC>2) crystallizing in monoclinic baddeleyite.

[0081] For the purposes of the present invention, the term "baddeleyite" means a natural zirconium oxide of formula ZrC>2, containing from 0.1% to 5% of hafnium oxide, and crystallizing in a monoclinic crystal system. The characteristics of baddeleyite such as the composition and the crystallographic structure, in particular the space group with the dimensions of the crystal lattice, are reported and accessible in the prior art and known to those skilled in the art, such as in Kudoh, Y. et al., (Phys Chem Minerals 13, 233-237 (1986)) or McCullough J D. et al. (Acta Crystallographica 12 (1959) 507-511).

[0082] According to a particular embodiment, the invention relates to the use as defined above, in which the support of the zirconium dioxide catalyst ZrC>2 comprises impurities such as Hafnium (Hf), Rhenium (Re) and Silicon (Si) atoms.

[0083] Advantageously, the mass percentage ratio between Hafnium atoms and zirconium atoms (Hf / Zr) is less than 5%. Advantageously, the mass percentage ratio between Rhenium atoms and zirconium atoms (Re / Zr) is less than 5%.

[0084] Advantageously, the mass percentage ratio between silicon atoms and zirconium atoms (Si / Zr) is less than 2%.

[0085] According to a particular embodiment, the invention relates to the use as defined above, in which said catalyst has a microstructure whose crystallite size is from 15 to 100 nm, preferably from 15 to 50 nm.

[0086] The crystalline structure of the catalyst can be analyzed by X-ray powder diffraction. The analysis of the phases present and that of their structure are carried out by the allocation of the diffraction peaks present in the diffraction diagram obtained in comparison with reference files.

[0087] The crystalline phase of zirconium dioxide baddeleyite ZrC>2 is for example indicated in the ICDD reference file n° 00-037-1484.

[0088] From the diffraction pattern, the crystallite size can be evaluated according to the following Scherrer formula: kl t = crystallite size t = — — — —

[0089] H.coso k = correction factor = 0.89

[0090] 1 = source wavelength

[0091] H = width at half height of the peak (in radians)

[0092] 6 = diffraction angle

[0093] The “15 to 100 nanometer” range includes the following ranges: 15 to 20 nm; 20 to 30 nm; 30 to 40 nm; 40 to 50 nm; 50 to 60 nm; 60 to 70 nm; 70 to 80 nm; 80 to 90 nm; 90 to 100 nm.

[0094] According to a particular embodiment, the invention relates to the use as defined above, in which: said catalyst has a surface area, analyzed by BET, of 1 to 250 m 2 / g, especially from 1 to 50 m 2 / g, and said catalyst comprises a crystalline phase, analyzed by X-ray diffraction, crystallized in a monoclinic crystalline system.

[0095] According to a particular embodiment, the invention relates to the use as defined above, in which: said catalyst has a surface area, analyzed by BET, of 1 to 10 m 2 / g, and said catalyst comprises a crystalline phase, analyzed by X-ray diffraction, crystallized in monoclinic baddeleyite, the crystallite size of which is preferably 15 to 100 nm, and optionally comprising impurities such as Hafnium (Hf), Rhenium (Re) and Silicon (Si) atoms.

[0096] According to a particular embodiment, the invention relates to the use as defined above, in which said catalyst has a surface area, analyzed by BET, of 1 to 250 m 2 / g, especially from 1 to 50 m 2 / g, preferably 1 to 10 m 2 / g, especially around 5 m 2 / g, optionally in which said catalyst comprises a crystalline phase, analyzed by X-ray diffraction, crystallized in a monoclinic crystalline system, in particular said crystalline phase represents from 50 to 90% by total weight of the catalyst, preferably said crystalline phase is baddeleyite and the crystallite size of which is preferably from 15 to 100 nm.

[0097] Use with a catalyst having specific Cu and Co contents

[0098] According to a particular embodiment, the invention relates to the use as defined above, in which the total content of the bimetallic elements copper and cobalt is from 0.5 to 25% by total weight of the catalyst.

[0099] The total weight of the catalyst includes the mass of the support and the mass of the bimetallic elements cobalt and copper.

[0100] The 0.5 to 25% range includes the following ranges: 0.5 to 5%; 5 to 10%; 10 to 15%; 15 to 20%; 20 to 25%

[0101] According to a particular embodiment, the invention relates to the use as defined above, in which the total content of bimetallic elements copper and cobalt is from 5 to 20% by total weight of the catalyst.

[0102] “Total content of bimetallic elements copper and cobalt” means a content corresponding to the addition of the elements copper and cobalt in the catalyst.

[0103] According to a particular embodiment, the invention relates to the use as defined above, in which the total content of the copper element is from 1 to 25% by total weight of the catalyst, in particular from 1 to 10% by total weight of the catalyst.

[0104] According to a particular embodiment, the invention relates to the use as defined above, in which the total content of the cobalt element is from 1 to 25% by total weight of the catalyst, in particular from 1 to 10% by total weight of the catalyst.

[0105] According to a particular embodiment, the invention relates to the use as defined above, in which: the total content of the copper element is from 1 to 25% by total weight of the catalyst, in particular from 1 to 10% by total weight of the catalyst, and the total content of the cobalt element is from 1 to 25% by total weight of the catalyst, in particular from 1 to 10% by total weight of the catalyst.

[0106] According to a particular embodiment, the invention relates to the use as defined above, in which the mass quantity of copper is greater than that of cobalt.

[0107] According to a particular embodiment, the invention relates to the use as defined above, in which the mass quantity of cobalt is greater than that of copper.

[0108] According to a particular embodiment, the invention relates to the use as defined above, in which the weight ratio between copper and cobalt varies from 1:1 to 1:10, in particular from 1:1 to 1:5.

[0109] According to a particular embodiment, the invention relates to the use as defined above, in which the mass composition of cobalt and copper of the catalyst is chosen from Co(10%)Cu(5%) and Co(15%)Cu(5%).

[0110] According to a particular embodiment, the invention relates to the use as defined above, in which the weight ratio between cobalt and copper varies from 1:1 to 1:10.

[0111] According to a particular embodiment, the invention relates to the use as defined above, in which the weight ratio between cobalt and copper varies from 1:1 to 1:5.

[0112] According to a particular embodiment, the invention relates to the use as defined above, in which:

[0113] - the weight ratio between cobalt and copper varies from 1:1 to 1:5,

[0114] - the copper content is 10% in total weight of the catalyst

[0115] - and the cobalt content is greater than or equal to 2% by total weight of the catalyst.

[0116] According to a particular embodiment, the invention relates to the use as defined above, in which the weight ratio between cobalt and copper varies from 1:2 to 1:5, the copper content is 10% by total weight of the catalyst, and the cobalt content is greater than or equal to 2% by total weight of the catalyst.

[0117] According to a particular embodiment, the invention relates to the use as defined above, in which:

[0118] - the weight ratio between cobalt and copper varies from 1:2 to 1:5,

[0119] - the copper content is 10% in total weight of the catalyst,

[0120] - the cobalt content is greater than or equal to 2% by total weight of the catalyst

[0121] - and the specific surface area measured by BET is 1 to 10 m 2 / g.

[0122] The inventors have surprisingly observed that when the CoCu / ZrC>2 catalyst comprises a mass quantity of copper greater than the mass quantity of cobalt, in particular with a weight ratio between cobalt and copper varying from 1:1 to 1:5 and when the copper content is 10% by total weight of the catalyst and when the cobalt content is greater than or equal to 2% by total weight of the catalyst, the yield of the hydrogenation reaction and its selectivity are improved, with values ​​respectively greater than 50% in yield and greater than 70% in selectivity.

[0123] When the CoCu / ZrC>2 catalyst comprises a mass quantity of copper greater than the mass quantity of cobalt, in particular with a weight ratio between cobalt and copper varying from 1:2 to 1:5 and when the copper content is 10% by total weight of the catalyst and the cobalt content is greater than or equal to 2% by total weight of the catalyst and the specific surface area of ​​the catalyst is from 1 to 10 m 2 / g, the yield of the hydrogenation reaction and its selectivity are improved, with values ​​respectively greater than 70% in yield and greater than 80% in selectivity.

[0124] According to a particular embodiment, the invention relates to the use as defined above, in which the mass composition of cobalt and copper of the catalyst is chosen from:

[0125] - Co(2%)Cu(10%);

[0126] - Co(5%)Cu(10%),

[0127] - Co(5%)Cu(5%),

[0128] - and Co(10%)Cu(10%), preferably Co(2%)Cu(10%) and Co(5%)Cu(10%), more preferably Co(5%)Cu(10%).

[0129] The mass composition Co(5%)Cu(10%) corresponds to a content of 5% Co in total weight of the catalyst and 10% Cu in total weight of the catalyst, i.e. a mass ratio between cobalt and copper of 1:2.

[0130] The mass composition Co(5%)Cu(5%) corresponds to a content of 5% by weight of Co and 5% by weight of Cu, i.e. a ratio between cobalt and copper of 1:1 with a content of 5% of Co in total weight of the catalyst and a content of 5% of Cu in total weight of the catalyst.

[0131] According to a particular embodiment, the invention relates to the use as defined above, in which the mass composition of cobalt and copper of the catalyst is chosen from Co(2%)Cu(10%); Co(5%)Cu(10%), more preferably Co(5%)Cu(10%), in which the mass content of copper is greater than the mass content of cobalt.

[0132] According to a particular embodiment, the invention relates to the use as defined above, in which the mass composition of cobalt and copper of the catalyst is Co(5%)Cu(10%) and the specific surface area is from 1 to 10 m 2 / g.

[0133] According to a particular embodiment, the invention relates to the use as defined above, in which the mass composition of cobalt and copper of the catalyst varies from Co(2%)Cu(10%) to Co(10%)Cu(10%). According to a particular embodiment, the invention relates to the use as defined above, in which: the total content of the copper element is from 5 to 10% by total weight of the catalyst, in particular 10% by total weight of the catalyst, and the total content of the cobalt element is from 2 to 10% by total weight of the catalyst, in particular 5% by total weight of the catalyst.

[0134] According to a particular embodiment, the invention relates to the use as defined above, in which the mass composition of cobalt and copper of the catalyst varies from Co(2%)Cu(10%) to Co(5%)Cu(10%).

[0135] According to a particular embodiment, the invention relates to the use as defined above, in which: the total content of the copper element is 10% by total weight of the catalyst, and the total content of the cobalt element is 2 to 5% by total weight of the catalyst, in particular 5% by total weight of the catalyst.

[0136] According to a particular embodiment, the invention relates to the use as defined above, in which: the total content of the copper element is 10% by total weight of the catalyst, the total content of the cobalt element is 2 to 5% by total weight of the catalyst, in particular 5% by total weight of the catalyst, and the specific surface area of ​​the catalyst is 1 to 50 m 2 / g, preferably 1 to 10 m 2 / g, analyzed by BET.

[0137] Use with a catalyst having a surface characteristic on Cu and Co

[0138] According to a particular embodiment, the invention relates to the use as defined above, in which said catalyst has an amount of more than 50 mol% of element copper at an oxidation state (II) and / or of element cobalt at an oxidation state (II).

[0139] The inventors unexpectedly found that for the hydrogenation reaction of oxalates to ethylene glycol, the bimetallic catalysts CoCu / ZrC>2 could be used directly after preparation by calcination in air without a prior step of reduction in hydrogen of the copper and cobalt atoms before use of the catalyst in the hydrogenation reaction.

[0140] Advantageously, in certain cases the use of a catalyst in which a majority of the copper and cobalt elements are already present in the oxidized state possibly makes it possible to use said catalyst without prior reduction of the copper and cobalt elements of the catalyst before carrying out the hydrogenation reaction of the oxalates to ethylene glycol. This also makes it possible to avoid storing the catalysts in an inert atmosphere to avoid oxidation of the copper and cobalt atoms. According to a particular embodiment, the invention relates to the use as defined above, in which said catalyst has an amount of more than 50 mol% of copper element at an oxidation state (II) and more than 50% of cobalt element at an oxidation state (II).

[0141] According to a particular embodiment, the invention relates to the use as defined above, in which said catalyst has an amount of more than 70 mol% of element copper at an oxidation state (II) and more than 65% of element cobalt at an oxidation state (II).

[0142] According to a particular embodiment, the invention relates to the use as defined above, in which said catalyst has an amount of more than 50 mol% of element copper at an oxidation state (II) in the form of CuO and more than 50% of element cobalt at an oxidation state (II) in the form of CO2O3 or Co(OH)2.

[0143] According to a particular embodiment, the invention relates to the use as defined above, in which said catalyst has an amount greater than 70 mol% of element copper at an oxidation state (II) in the form of CuO and an amount greater than 65 mol% of element cobalt at an oxidation state (II) in the form of CO2O3 or Co(OH)2.

[0144] According to a particular embodiment, the invention relates to the use as defined above, in which said catalyst has:

[0145] - a quantity of 10 to 30 mol% of copper element in metallic state at oxidation state (0) or oxidation state (I) in the form of CU2O

[0146] -and a quantity of 10 to 35 mol% of cobalt element in the metallic state at an oxidation state (0).

[0147] According to a particular embodiment, the invention relates to the use as defined above, in which said catalyst has: an amount greater than 70 mol% of element copper in an oxidation state (II) in the form of CuO, an amount of 10 to 30 mol% of element copper in the metallic state in an oxidation state (0) or in an oxidation state (I) in the form of CU2O an amount of 10 to 35 mol% of element cobalt in the metallic state in an oxidation state (0), and an amount greater than 65 mol% of element cobalt in an oxidation state (II) in the form of CO2O3 or Co(OH)2.

[0148] Use with a catalyst of particular morphology

[0149] According to a particular embodiment, the invention relates to the use as defined above, in which said catalyst is in the form of a population of micrometric particles from 1 to 500 pm. The range from 1 to 500 pm includes the following ranges: from 1 to 50 pm; from 50 to 100 pm; from 100 to 200 pm; from 200 to 300 pm, from 300 to 400 pm.

[0150] By "particles" we mean distinct clusters having either visual or mechanical coherence.

[0151] According to a particular embodiment, the invention relates to the use as defined above, in which said catalyst is in the form of a population of particles of rounded morphology.

[0152] For the purposes of the present invention, the term "rounded particles" means particles having no edge, corner or beveled edge.

[0153] Use with selectivity of hydrogenation reaction

[0154] The selectivity of a chemical reaction specifies the amount of the desired product formed relative to the number of moles of the limiting reactant consumed. It indicates whether multiple reactions occur in parallel, leading to unwanted by-products, or whether the reaction being performed is the only one to consume reactant.

[0155] In the case of the hydrogenation step, selectivity is defined as the amount of ethylene glycol obtained relative to the total amount of products that were obtained including ethylene glycol and secondary by-products, resulting from the transformation of the oxalate compound.

[0156] The term "selective reaction" means a reaction that produces the target product, ethylene glycol, with a selectivity of more than 50%.

[0157] According to a particular embodiment, the invention relates to the use as defined above, in which the hydrogenation reaction of said oxalate compound by hydrogen to obtain ethylene glycol is selective, with a selectivity of more than 70%.

[0158] According to a particular embodiment, the invention relates to the use as defined above, in which the hydrogenation reaction of said oxalate compound by hydrogen to obtain ethylene glycol is selective, with a selectivity of more than 80%.

[0159] According to a particular embodiment, the invention relates to the use as defined above, in which the hydrogenation reaction of said oxalate compound by hydrogen to obtain ethylene glycol is selective, with a selectivity of more than 90%.

[0160] According to a particular embodiment, the invention relates to the use as defined above, in which the hydrogenation reaction of said oxalate compound by hydrogen to obtain ethylene glycol is selective, with a selectivity greater than or equal to 95%.

[0161] Use with hydrogenation reaction yield Chemical yield describes the efficiency of the chemical reaction being studied. Yield refers to the ratio of the amount of product obtained to the maximum amount that would be obtained if the reaction were complete.

[0162] The yield of the hydrogenation reaction of oxalate to ethylene glycol according to the invention is determined as a percentage of moles of ethylene glycol obtained per mole of oxalate.

[0163] The yield of the hydrogenation reaction of oxalate to ethylene glycol can be determined using gas chromatography coupled with a mass spectrometer (GC-MS) in which mesitylene is used as an internal standard.

[0164] According to a particular embodiment, the invention relates to the use as defined above, in which the hydrogenation reaction of said oxalate compound with hydrogen to obtain ethylene glycol has a yield of more than 50%, in particular more than 70%, preferably more than 80%.

[0165] According to a particular embodiment, the invention relates to the use as defined above, in which the hydrogenation reaction of said oxalate compound with hydrogen to obtain ethylene glycol is selective, with a selectivity of more than 70%, preferably more than 90%, preferentially greater than or equal to 95% and / or in which the hydrogenation reaction of said oxalate compound with hydrogen to obtain ethylene glycol has a yield of more than 70%, preferably more than 80%.

[0166] Catalyst

[0167] A second subject of the invention relates to a bimetallic supported catalyst comprising copper and cobalt on a zirconium dioxide support, of formula CoCu / ZrC>2, in which said catalyst has a surface area, analyzed by BET, of 1 to 250 m 2 / g. According to a particular embodiment, the invention relates to a bimetallic supported catalyst as defined above, in which said catalyst has a surface area, analyzed by BET, of 1 to 75 m 2 / g, preferably 1 to 50 m 2 / g.

[0168] According to a particular embodiment, the invention relates to a bimetallic supported catalyst as defined above, in which said catalyst has a surface area, analyzed by BET, of 1 to 250 m 2 / g, and wherein said catalyst comprises a crystalline phase, analyzed by X-ray diffraction, crystallized in a monoclinic crystalline system.

[0169] Specific surface area According to a particular embodiment, the invention relates to a bimetallic supported catalyst as defined above, in which said catalyst has a surface area, analyzed by BET, of 1 to 50 m 2 / g.

[0170] According to a particular embodiment, the invention relates to a bimetallic supported catalyst as defined above, in which said catalyst has a surface area, analyzed by BET, of 1 to 10 m 2 / g, preferably about 5 m 2 / g.

[0171] Structure

[0172] According to a particular embodiment, the invention relates to a bimetallic supported catalyst as defined above, in which said crystalline phase represents from 50 to 90% by total weight of the catalyst.

[0173] According to a particular embodiment, the invention relates to a bimetallic supported catalyst as defined above, in which said crystalline phase is Baddeleyite. According to a particular embodiment, the invention relates to a bimetallic catalyst as defined above, in which said zirconium dioxide support comprises a crystalline phase, analyzed by X-ray diffraction, crystallized in a monoclinic crystalline system.

[0174] According to a particular embodiment, the invention relates to a bimetallic catalyst as defined above, said crystalline phase represents from 50 to 90% by total weight of the catalyst.

[0175] The 50-90% range includes the following ranges: 50-55%, 55-60%, 60-65%, 65-70%, 70-75%, 75-80%, 80-85%, 85-90%.

[0176] According to a particular embodiment, the invention relates to a bimetallic catalyst as defined above, in which said crystalline phase is baddeleyite.

[0177] Advantageously, the catalyst according to the invention comprises from 50 to 90% baddeleyite. Advantageously, the support of the zirconium dioxide catalyst according to the invention consists of more than 50% baddeleyite, in particular from 50 to 100% baddeleyite.

[0178] According to a particular embodiment, the invention relates to a bimetallic catalyst as defined above, in which said catalyst comprises a crystalline phase, analyzed by X-ray diffraction, comprising a crystallite size of 15 to 100 nm.

[0179] According to a particular embodiment, the invention relates to a bimetallic supported catalyst as defined above, in which the catalyst support made of zirconium dioxide ZrC>2 comprises impurities such as Hafnium (Hf), Rhenium (Re) and Silicon (Si) atoms. Advantageously, the mass percentage ratio between Hafnium atoms and zirconium atoms (Hf / Zr) is less than 5%.

[0180] Advantageously, the mass percentage ratio between Rhenium atoms and zirconium atoms (Re / Zr) is less than 5%.

[0181] Advantageously, the mass percentage ratio between silicon atoms and zirconium atoms (Si / Zr) is less than 2%.

[0182] According to a particular embodiment, the invention relates to a bimetallic supported catalyst as defined above, in which said catalyst has a microstructure whose crystallite size is from 15 to 100 nm, preferably from 15 to 50 nm.

[0183] According to a particular embodiment, the invention relates to a bimetallic supported catalyst as defined above, in which: said catalyst has a surface area, analyzed by BET, of 1 to 250 m 2 / g, especially from 1 to 50 m 2 / g, preferably 1 to 10 m 2 g, and said catalyst comprises a crystalline phase, analyzed by X-ray diffraction, crystallized in a monoclinic crystalline system.

[0184] According to a particular embodiment, the invention relates to a bimetallic supported catalyst as defined above, in which: said catalyst has a surface area, analyzed by BET, of 1 to 10 m 2 / g, and said catalyst comprises a crystalline phase, analyzed by X-ray diffraction, crystallized in monoclinic baddeleyite whose crystallite size is 15 to 100 nm, preferably 15 to 50 nm. and comprising impurities such as Hafnium (Hf), Rhenium (Re) and Silicon (Si) atoms.

[0185] According to a particular embodiment, the invention relates to a bimetallic supported catalyst as defined above, comprising copper and cobalt on a zirconium dioxide support, of formula CoCu / ZrC>2, in which said catalyst has a surface area, analyzed by BET, of 1 to 250 m 2 / g, preferably 1 to 50 m 2 / g, preferably from 1 to 10 m 2 / g, especially around 5 m 2 / g and wherein said catalyst comprises a crystalline phase, analyzed by X-ray diffraction, crystallized in a monoclinic crystalline system, in particular said crystalline phase represents from 50 to 90% by total weight of the catalyst, preferably said crystalline phase is baddeleyite and preferably comprising a crystallite size of 15 to 100 nm.

[0186] Composition

[0187] According to a particular embodiment, the invention relates to a bimetallic supported catalyst as defined above, wherein said catalyst comprises a total content of the bimetallic elements copper and cobalt of 0.5 to 25% by total weight of the catalyst. According to a particular embodiment, the invention relates to a bimetallic supported catalyst as defined above, wherein said catalyst comprises a total content of the bimetallic elements copper and cobalt of 5 to 20%.

[0188] According to a particular embodiment, the invention relates to a bimetallic supported catalyst as defined above, in which the total content of the copper element is from 1 to 25% by total weight of the catalyst, preferably from 1 to 10% by total weight of the catalyst.

[0189] According to a particular embodiment, the invention relates to a bimetallic supported catalyst as defined above, in which the total content of the cobalt element is from 1 to 25% by total weight of the catalyst, preferably from 1 to 10% by total weight of the catalyst.

[0190] According to a particular embodiment, the invention relates to a catalyst as defined above, in which the mass quantity of cobalt is greater than that of copper.

[0191] According to a particular embodiment, the invention relates to a catalyst as defined above, in which the weight ratio between copper and cobalt varies from 1:1 to 1:10, in particular from 1:1 to 1:5.

[0192] According to a particular embodiment, the invention relates to a catalyst as defined above, in which the mass composition of cobalt and copper of the catalyst is chosen from Co(10%)Cu(5%) and Co(15%)Cu(5%).

[0193] According to a particular embodiment, the invention relates to a catalyst as defined above, in which the mass quantity of copper is greater than that of cobalt.

[0194] According to a particular embodiment, the invention relates to a bimetallic supported catalyst as defined above, in which the weight ratio between cobalt and copper varies from 1:1 to 1:10.

[0195] According to a particular embodiment, the invention relates to a bimetallic supported catalyst as defined above, in which the weight ratio between cobalt and copper varies from 1:1 to 1:5.

[0196] According to a particular embodiment, the invention relates to a bimetallic supported catalyst as defined above, in which the weight ratio between cobalt and copper varies from 2:10 to 5:10.

[0197] According to a particular embodiment, the invention relates to a bimetallic supported catalyst as defined above, in which the mass composition of cobalt and copper of the catalyst is chosen from:

[0198] - Co(2%)Cu(10%) ;

[0199] - Co(5%)Cu(10%),

[0200] - Co(5%)Cu(5%),

[0201] - and Co(10%)Cu(10%), preferably Co(2%)Cu(10%) and Co(5%)Cu(10%), more preferably Co(5%)Cu(10%). According to a particular embodiment, the invention relates to a bimetallic supported catalyst as defined above, in which the mass composition of cobalt and copper of the catalyst is chosen from Co(2%)Cu(10%) and Co(5%)Cu(10%), more preferably Co(5%)Cu(10%), in which the mass content of copper is greater than the mass content of cobalt.

[0202] According to a particular embodiment, the invention relates to a bimetallic supported catalyst as defined above, in which the mass composition of cobalt and copper of the catalyst is Co(5%)Cu(10%) and the specific surface area is from 1 to 10 m 2 / g.

[0203] According to a particular embodiment, the invention relates to a bimetallic supported catalyst as defined above, in which the mass composition of cobalt and copper of the catalyst varies from Co(2%)Cu(10%) to Co(10%)Cu(10%).

[0204] According to a particular embodiment, the invention relates to a bimetallic supported catalyst as defined above, in which the total content of the copper element is from 5 to 10% by total weight of the catalyst, in particular 10% by total weight of the catalyst, and the total content of the cobalt element is from 2 to 10% by total weight of the catalyst, in particular 5% by total weight of the catalyst.

[0205] According to a particular embodiment, the invention relates to a bimetallic supported catalyst as defined above, in which the mass composition of cobalt and copper of the catalyst varies from Co(2%)Cu(10%) to Co(5%)Cu(10%).

[0206] According to a particular embodiment, the invention relates to a bimetallic supported catalyst as defined above, in which: the total content of the copper element is 10% by total weight of the catalyst, and the total content of the cobalt element is 2 to 5% by total weight of the catalyst, in particular 5% by total weight of the catalyst.

[0207] According to a particular embodiment, the invention relates to a bimetallic supported catalyst as defined above, in which: the total content of the cobalt element is from 2 to 5% by total weight of the catalyst, in particular 5% by total weight of the catalyst, and the specific surface area of ​​the catalyst is from 1 to 50 m 2 / g, preferably 1 to 10 m 2 / g, analyzed by BET.

[0208] According to a particular embodiment, the invention relates to a bimetallic supported catalyst as defined above, in which: the total content of the cobalt element is from 2 to 5% by total weight of the catalyst, in particular 5% by total weight of the catalyst, the specific surface area of ​​the catalyst is from 1 to 50 m 2 / g, preferably 1 to 10 m 2 / g, analyzed by BET, and comprises a crystalline phase, analyzed by X-ray diffraction, crystallized in a monoclinic crystal system, in particular baddeleyite, the crystallite size of which is preferably 15 to 100 nm, preferably 15 to 50 nm and in particular comprising impurities of Hafnium, Rhenium and Silicon.

[0209] Oxidation degree of Co and Cu on the surface

[0210] According to a particular embodiment, the invention relates to a bimetallic supported catalyst as defined above, in which said catalyst has an amount of more than 50 mol% of element copper at an oxidation state (II) and / or element cobalt at an oxidation state (II).

[0211] Advantageously, a bimetallic catalyst in which the majority of the copper and cobalt elements are already present in the oxidized state makes it possible to use said catalyst without prior reduction of the copper and cobalt elements of the catalyst before carrying out the hydrogenation reaction of the oxalates to ethylene glycol. This also makes it possible to avoid storing the catalysts in an inert atmosphere to avoid oxidation of the copper and cobalt atoms.

[0212] According to a particular embodiment, the invention relates to a catalyst as defined above, in which said catalyst has an amount of more than 50 mol% of element copper at an oxidation state (II) and more than 50% of element cobalt at an oxidation state (II).

[0213] According to a particular embodiment, the invention relates to a catalyst as defined above, in which said catalyst has an amount of more than 70 mol% of element copper at an oxidation state (II) and more than 65% of element cobalt at an oxidation state (II).

[0214] According to a particular embodiment, the invention relates to a catalyst as defined above, in which said catalyst has an amount of more than 50 mol% of element copper at an oxidation state (II) in the form of CuO and more than 50% of element cobalt at an oxidation state (II) in the form of CO2O3 or Co(OH)2.

[0215] According to a particular embodiment, the invention relates to a catalyst as defined above, in which said catalyst has an amount greater than 70 mol% of element copper at an oxidation state (II) in the form of CuO and an amount greater than 65 mol% of element cobalt at an oxidation state (II) in the form of CO2O3 or Co(OH)2.

[0216] According to a particular embodiment, the invention relates to a catalyst as defined above, in which said catalyst has: - an amount of 10 to 30 mol% of copper element in the metallic state at an oxidation state (0) or at an oxidation state (I) in the form of CU2O

[0217] -and a quantity of 10 to 35 mol% of cobalt element in the metallic state at an oxidation state (0).

[0218] According to a particular embodiment, the invention relates to a catalyst as defined above, in which said catalyst has: an amount greater than 70 mol% of element copper in an oxidation state (II) in the form of CuO, an amount of 10 to 30 mol% of element copper in the metallic state in an oxidation state (0) or in an oxidation state (I) in the form of CU2O an amount of 10 to 35 mol% of element cobalt in the metallic state in an oxidation state (0), and an amount greater than 65 mol% of element cobalt in an oxidation state (II) in the form of CO2O3 or Co(OH)2.

[0219] According to a particular embodiment, the invention relates to a catalyst as defined above, in which said catalyst has:

[0220] - a quantity of more than 50 mol% of the element copper in oxidation state (II) and more than 50% of the element cobalt in oxidation state (II),

[0221] - a specific surface area of ​​1 to 50 m 2 / g

[0222] - a crystalline phase, analyzed by X-ray diffraction, crystallized in a monoclinic crystalline system.

[0223] According to a particular embodiment, the invention relates to a catalyst as defined above, in which said catalyst has: an amount greater than 70 mol% of element copper in an oxidation state (II) in the form of CuO, an amount of 10 to 30 mol% of element copper in the metallic state in an oxidation state (0) or in an oxidation state (I) in the form of CU2O an amount of 10 to 35 mol% of element cobalt in the metallic state in an oxidation state (0), an amount greater than 65 mol% of element cobalt in an oxidation state (II) in the form of CO2O3 or Co(OH)2. a specific surface area of ​​1 to 50 m 2 / g, especially from 1 to 10 m 2 / g analyzed by BET, and a crystalline phase, analyzed by X-ray diffraction, crystallized in a monoclinic crystal system, notably baddeleyite, in particular comprising impurities of Hafnium, Rhenium and Silicon.

[0224] Advantageously in said catalyst as defined: - the mass percentage ratio between Hafnium atoms and zirconium atoms (Hf / Zr) is less than 5%,

[0225] - the mass percentage ratio between Rhenium atoms and zirconium atoms (Re / Zr) is less than 5%,

[0226] - and the mass percentage ratio between Silicon atoms and zirconium atoms (Si / Zr) is less than 2%.

[0227] Morphology

[0228] According to a particular embodiment, the invention relates to a bimetallic supported catalyst as defined above, in which said catalyst is in the form of micrometric particles of 1 to 500 pm.

[0229] Said particles are in particular made up of an agglomerate of rods with a length to thickness ratio of 1 to 10, and an average thickness of 50 to 500 nm.

[0230] As a non-limiting example, morphology and average size can be assessed by scanning electron microscopy (SEM).

[0231] Micrometric sizes allow easier handling of the catalyst.

[0232] According to a particular embodiment, the invention relates to a bimetallic supported catalyst as defined above, in which said catalyst comprises a total content of the bimetallic elements copper and cobalt of 0.5 to 25% by total weight of the catalyst, preferably the weight ratio between cobalt and copper varies from 1:1 to 1:10, preferentially from 1:1 to 1:5, in particular the mass composition of cobalt and copper of the catalyst is chosen from:

[0233] - Co(2%)Cu(10%),

[0234] - Co(5%)Cu(10%),

[0235] - Co(5%)Cu(5%),

[0236] - and Co(10%)Cu(10%), preferably Co(2%)Cu(10%) and Co(5%)Cu(10%), more preferably Co(5%)Cu(10%), and / or wherein said catalyst has an amount of more than 50 mol% of element copper at oxidation state (II) and / or element cobalt at oxidation state (II), and / or wherein said catalyst is in the form of a population of micrometric particles of 1 to 500 pm, preferably in the form of a population of particles with a rounded morphology.

[0237] Characteristics of the catalyst under reducing atmosphere

[0238] According to a particular embodiment, the invention relates to a bimetallic supported catalyst as defined above, in which said catalyst analyzed by programmed temperature reduction (PTR) carried out in a dihydrogen reducing atmosphere over a temperature range of 30 to 900°C, is characterized by a reduction temperature of the metallic copper of oxidation state (0) in the range of 150 to 250°C.

[0239] Advantageously, said reduction temperature of metallic copper is in a temperature range of 170 to 180°C, preferably 174°C.

[0240] Advantageously, at a temperature higher, in particular at least 10°C, than said reduction temperature of metallic copper, the copper atoms are more than 80%, in particular 80 to 100%, preferably 100% in metallic form.

[0241] The 80-100% range includes the following ranges: 80-85%, 85-90%, 90-95%, 95-96%, 96-97%, 97-98%, 98-99%, 99-100%.

[0242] Advantageously, at a temperature higher, in particular by at least 10°C, than said reduction temperature of metallic copper, the cobalt atoms are 80 to 100%, preferably 100% in oxidized form, i.e. at a degree of oxidation greater than zero.

[0243] Advantageously, at a temperature higher, in particular by at least 10°C, than said reduction temperature of metallic copper, the cobalt atoms are from 0 to 20%, in particular from 0 to 10%, preferably less than 5%, in metallic form at a zero oxidation state.

[0244] The range from 0 to 20% includes the following values: 0.0%; 0.05%, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, 20%.

[0245] According to a particular embodiment, the invention relates to a bimetallic supported catalyst as defined above, wherein said catalyst analyzed by programmed temperature reduction (PTR) carried out in a dihydrogen reducing atmosphere over a temperature range of 30 to 900°C, is characterized by a reduction temperature of the metallic copper of oxidation state (0) in the range of 150 to 250°C, in particular at a temperature higher than at least 10°C of said reduction temperature of the metallic copper analyzed by PTR, the copper atoms are 80 to 100%, preferably 100% in metallic form, the cobalt atoms are 80 to 100%, preferably 100% in oxidized form.

[0246] According to a particular embodiment, the invention relates to a bimetallic supported catalyst as defined above, wherein said catalyst analyzed by programmed temperature reduction (PTR) carried out at a reducing atmosphere under a flow of 5 vol. % H2 in Argon, in particular at 30 mL / min, over a temperature range of 30 to 900°C, in particular with a heating rate of 5°C / min, is characterized by a reduction temperature of metallic copper of oxidation state (0) in the range of 150 to 250°C.

[0247] Advantageously, the catalyst is pretreated under an inert atmosphere before said analysis, in particular at 200°C under Helium.

[0248] According to a particular embodiment, the invention relates to a bimetallic supported catalyst as defined above, in which said catalyst under reduced atmosphere comprising dihydrogen at a pressure of 2 to 10 MPa and at a temperature of 150 to 250°C, in particular 180 to 220°C, comprises:

[0249] - from 80 to 100%, in particular 95 to 100%, preferably 100%, of the metallic copper atoms Cu(0) and

[0250] - from 80 to 100% of cobalt atoms in an oxidation state greater than zero.

[0251] Advantageously, the copper atoms are 95%, preferably 100% in metallic form.

[0252] Advantageously, the cobalt atoms are 80 to 100%, in particular 95 to 100%, preferably 100%, in oxidized form to an oxidation state greater than zero.

[0253] Advantageously, the cobalt atoms are from 0 to 20%, in particular from 0 to 15%, preferably less than 20%, in metallic form.

[0254] Process for the preparation of ethylene glycol

[0255] A third subject of the invention relates to a process for preparing ethylene glycol comprising: o a step of hydrogenation by hydrogen of an oxalate compound, into ethylene glycol, in the presence of a bimetallic supported catalyst comprising copper and cobalt on a zirconium dioxide support, of formula CoCu / ZrC>2.

[0256] According to a particular embodiment, the invention relates to a preparation process as defined above, in which said oxalate compound is of the following Formula 1:

[0257] Formula 1 in which R a represents:

[0258] • a linear or branched C1 to C20 alkyl group,

[0259] • a C3 to C10 cycloalkyl group, • a C8 to C20 aryl or heteroaryl group

[0260] • a C5 to C20 alkyl-aryl or alkyl-heteroaryl group.

[0261] According to a particular embodiment, the invention relates to a process for preparing ethylene glycol as defined above in which said oxalate compound is chosen from dimethyloxalate, diethyloxalate, diphenyloxalate, dibenzyloxalate, isopropyloxalate and diterbutyloxalate.

[0262] According to a particular embodiment, the invention relates to a process for preparing ethylene glycol as defined above, in which:

[0263] • the hydrogenation step comprises o bringing into contact: said oxalate compound, dihydrogen, said supported catalyst of formula CoCu / ZrC>2, comprising cobalt and copper on a zirconium dioxide support, optionally a solvent, to obtain a reaction medium optionally pressurized, o optionally heating said reaction medium, to obtain ethylene glycol.

[0264] According to a particular embodiment, the invention relates to a process for preparing ethylene glycol as defined above, in which:

[0265] • the hydrogenation step comprises o bringing into contact: said oxalate compound, dihydrogen, said supported catalyst of formula CoCu / ZrC>2, comprising cobalt and copper on a zirconium dioxide support, a solvent, to obtain a reaction medium, o optionally heating said reaction medium, to obtain ethylene glycol.

[0266] According to a particular embodiment, the invention relates to a process for preparing ethylene glycol as defined above, in which:

[0267] • the hydrogenation step comprises o bringing into contact: said oxalate compound, dihydrogen, Tl of said supported catalyst of formula CoCu / ZrC>2, comprising cobalt and copper on a zirconium dioxide support, with a solvent, to obtain a reaction medium, o heating of said reaction medium, to obtain ethylene glycol.

[0268] According to a particular embodiment, the invention relates to a process for preparing ethylene glycol as defined above, in which:

[0269] • the hydrogenation step comprises o bringing into contact: said oxalate compound, dihydrogen, said supported catalyst of formula CoCu / ZrC>2, comprising copper and cobalt on a zirconium dioxide support, a solvent, to obtain a reaction medium placed under pressure, o heating said reaction medium to obtain ethylene glycol.

[0270] According to a particular embodiment, the invention relates to a process for preparing ethylene glycol as defined above, in which said oxalate is chosen from dimethyloxalate, diethyloxalate, dibenzyloxalate, diterbutyloxalate, diisopropyloxalate, diphenyloxalate.

[0271] According to a particular embodiment, the invention relates to a process for preparing ethylene glycol as defined above, in which said oxalate is chosen from dimethyloxalate and diethyloxalate, preferably diethyloxalate.

[0272] Advantageously, the oxalates used can be obtained by a carbonylation reaction of an alcohol in the presence of CO and oxygen.

[0273] Advantageously, carbon monoxide CO for the preparation of oxalate comes from the electrolysis of carbon dioxide CO2 into carbon monoxide CO.

[0274] Thus, advantageously, the synthesis of ethylene glycol is carried out from the recovery of CO2 and an alcohol.

[0275] Process for the preparation of ethylene glycol with conditions on the catalyst used According to a particular embodiment, the invention relates to a process for the preparation of ethylene glycol as defined above, in which said catalyst is according to the catalyst of the invention as defined above. According to a particular embodiment, the invention relates to a process for the preparation of ethylene glycol as defined above, in which said catalyst is prepared by mixing the support in powder form and an aqueous solution of copper and cobalt salts, followed by calcination.

[0276] According to a particular embodiment, the invention relates to a process for preparing ethylene glycol as defined above, in which said catalyst is prepared by mixing the support in powder form and an aqueous solution of copper and cobalt salts, without adding additives or surfactants, followed by calcination.

[0277] Advantageously, the catalyst used in the process as defined above is prepared according to a preparation process comprising the following steps:

[0278] • a step A of impregnation of a cobalt salt and a copper salt, dissolved in an aqueous solution, in a volume of water of 5 to 10 mL, on a zirconium dioxide support in powder form, with a mass ratio of the solution / mass of support of from 0.6 to 1.0; to obtain the CoCu / ZrC>2 catalyst in the form of a homogeneous mixture,

[0279] • a step B of drying said homogeneous mixture, to obtain the CoCu / ZrC>2 catalyst in the form of a dry homogeneous mixture,

[0280] • an activation step C, comprising calcination of said dry homogeneous mixture to obtain said catalyst.

[0281] Advantageously, in impregnation step A, said aqueous solution containing the cobalt and copper salts is free of additives and surfactants. In other words, said aqueous impregnation solution consists of a demineralized water solution in which the cobalt and copper salts are dissolved.

[0282] Advantageously, the cobalt salt is cobalt nitrate and the copper salt is copper nitrate.

[0283] The process for preparing ethylene glycol as defined above according to the invention is therefore implemented with a catalyst prepared with an aqueous solution, advantageously free of additives and surfactants, which makes it more industrializable and at lower cost.

[0284] According to a particular embodiment, the invention relates to a process for preparing ethylene glycol as defined above, in which said catalyst has a surface area, analyzed by BET, of 1 to 250 m2 / g.

[0285] According to a particular embodiment, the invention relates to a process for preparing ethylene glycol as defined above, in which said catalyst has a surface area, analyzed by BET, of 1 to 50 m 2 / g. According to a particular embodiment, the invention relates to a process for preparing ethylene glycol as defined above, in which said catalyst has a surface area, analyzed by BET, of 1 to 10 m 2 / g, preferably about 5 m 2 / g.

[0286] According to a particular embodiment, the invention relates to a process for preparing ethylene glycol as defined above, in which said catalyst comprises a crystalline phase, analyzed by X-ray diffraction, crystallized in a monoclinic crystalline system.

[0287] According to a particular embodiment, the invention relates to a process for preparing ethylene glycol as defined above, in which said crystalline phase of the catalyst represents from 50 to 90% by total weight of the catalyst.

[0288] According to a particular embodiment, the invention relates to a process for preparing ethylene glycol as defined above, in which said crystalline phase is baddeleyite.

[0289] According to a particular embodiment, the invention relates to a process for preparing ethylene glycol as defined above, in which the size of the crystallites of said crystalline phase is from 15 to 40 nm.

[0290] According to a particular embodiment, the invention relates to a process for preparing ethylene glycol as defined above, in which said zirconium dioxide support of said CoCu / ZrC>2 catalyst comprises baddeleyite in a proportion of 50 to 90% by total weight of the catalyst.

[0291] The 50-90% range includes the following ranges: 50-55%, 55-60%, 60-65%, 65-70%, 70-75%, 75-80%, 80-85%, 85-90%.

[0292] According to a particular embodiment, the invention relates to a process for preparing ethylene glycol as defined above, in which said catalyst comprises a total content of the bimetallic elements copper and cobalt of 0.5 to 25% by total weight of the catalyst.

[0293] According to a particular embodiment, the invention relates to a process for preparing ethylene glycol as defined above, in which said catalyst comprises a total content of the bimetallic elements copper and cobalt of 5 to 20%.

[0294] According to a particular embodiment, the invention relates to a process for preparing ethylene glycol as defined above, in which the total content of the element copper is from 1 to 25% by total weight of the catalyst, preferably from 1 to 10% by total weight of the catalyst. According to a particular embodiment, the invention relates to a process for preparing ethylene glycol as defined above, in which the total content of the element cobalt is from 1 to 25% by total weight of the catalyst, preferably from 1 to 10% by total weight of the catalyst. According to a particular embodiment, the invention relates to a process for preparing ethylene glycol as defined above, in which the mass quantity of cobalt is greater than that of copper.

[0295] According to a particular embodiment, the invention relates to a process for preparing ethylene glycol as defined above, in which the weight ratio between copper and cobalt varies from 1:1 to 1:10, in particular from 1:1 to 1:5.

[0296] According to a particular embodiment, the invention relates to a process for preparing ethylene glycol as defined above, in which the mass composition of cobalt and copper of the catalyst is chosen from Co(10%)Cu(5%) and Co(15%)Cu(5%).

[0297] According to a particular embodiment, the invention relates to a process for preparing ethylene glycol as defined above, in which the mass quantity of copper is greater than that of cobalt.

[0298] According to a particular embodiment, the invention relates to a process for preparing ethylene glycol as defined above, in which said catalyst has a weight ratio between cobalt and copper varying from 1:1 to 1:10.

[0299] According to a particular embodiment, the invention relates to a process for preparing ethylene glycol as defined above, in which said catalyst has a weight ratio between cobalt and copper varying from 2:10 to 5:10

[0300] According to a particular embodiment, the invention relates to a process for preparing ethylene glycol as defined above, in which the mass composition of cobalt and copper of the catalyst is chosen from:

[0301] - Co(2%)Cu(10%),

[0302] - Co(5%)Cu(10%),

[0303] - Co(5%)Cu(5%),

[0304] - and Co(10%)Cu(10%), preferably Co(2%)Cu(10%) and Co(5%)Cu(10%), more preferably Co(5%)Cu(10%).

[0305] According to a particular embodiment, the invention relates to a process for preparing ethylene glycol as defined above, in which said catalyst comprises a total content of bimetallic elements copper and cobalt of 0.5 to 25% by total weight of the catalyst and in which the weight ratio between cobalt and copper varies from 1:1 to 1:5, in particular the mass composition of cobalt and copper of the catalyst is chosen from:

[0306] - Co(2%)Cu(10%),

[0307] - Co(5%)Cu(10%),

[0308] - Co(5%)Cu(5%),

[0309] - and Co(10%)Cu(10%), preferably Co(2%)Cu(10%) and Co(5%)Cu(10%), more preferably Co(5%)Cu(10%).

[0310] According to a particular embodiment, the invention relates to a process for preparing ethylene glycol as defined above, in which the mass composition of cobalt and copper of the catalyst is chosen from Co(2%)Cu(10%) or Co(5%)Cu(10%), more preferably Co(5%)Cu(10%), in which the mass content of copper is greater than the mass content of cobalt.

[0311] According to a particular embodiment, the invention relates to a process for preparing ethylene glycol as defined above, in which the mass composition of cobalt and copper of the catalyst is Co(5%)Cu(10%) and the specific surface area is from 1 to 10 m 2 / g.

[0312] According to a particular embodiment, the invention relates to a process for preparing ethylene glycol as defined above, in which the mass composition of cobalt and copper of the catalyst varies from Co(2%)Cu(10%) to Co(10%)Cu(10%).

[0313] According to a particular embodiment, the invention relates to a process for preparing ethylene glycol as defined above, in which in said catalyst: the total content of the copper element is from 5 to 10% by total weight of the catalyst, in particular 10% by total weight of the catalyst, and the total content of the cobalt element is from 2 to 10% by total weight of the catalyst, in particular 5% by total weight of the catalyst.

[0314] According to a particular embodiment, the invention relates to a process for preparing ethylene glycol as defined above, in which the mass composition of cobalt and copper of the catalyst varies from Co(2%)Cu(10%) to Co(5%)Cu(10%).

[0315] According to a particular embodiment, the invention relates to a process for preparing ethylene glycol as defined above, in which in said catalyst: the total content of the copper element is 10% by total weight of the catalyst, and the total content of the cobalt element is 2 to 5% by total weight of the catalyst, in particular 5% by total weight of the catalyst.

[0316] According to a particular embodiment, the invention relates to a process for preparing ethylene glycol as defined above, in which in said catalyst: the total content of the element cobalt is from 2 to 5% by total weight of the catalyst, in particular 5% by total weight of the catalyst, and the specific surface area of ​​the catalyst is from 1 to 50 m 2 / g, preferably 1 to 10 m 2 / g, analyzed by BET.

[0317] According to a particular embodiment, the invention relates to a process for preparing ethylene glycol as defined above, in which in said catalyst: the total content of the element cobalt is from 2 to 5% by total weight of the catalyst, in particular 5% by total weight of the catalyst, the specific surface area of ​​the catalyst is from 1 to 50 m 2 / g, preferably 1 to 10 m 2 / g, analyzed by BET, and said catalyst comprises a crystalline phase, analyzed by X-ray diffraction, crystallized in a monoclinic crystal system, in particular baddeleyite, the crystallite size of which is preferably 15 to 100 nm, in particular 15 to 50 nm, in particular comprising impurities of Hafnium, Rhenium and Silicon.

[0318] According to a particular embodiment, the invention relates to a process for preparing ethylene glycol as defined above, in which said catalyst has an amount of more than 50 mol% of element copper at an oxidation state (II) and / or element cobalt at an oxidation state (II).

[0319] According to a particular embodiment, the invention relates to a process for preparing ethylene glycol as defined above, in which said catalyst has an amount of more than 50 mol% of element copper at an oxidation state (II) and more than 50% of element cobalt at an oxidation state (II).

[0320] According to a particular embodiment, the invention relates to a process for preparing ethylene glycol as defined above, in which said catalyst has an amount of more than 70 mol% of element copper at an oxidation state (II) and more than 65% of element cobalt at an oxidation state (II).

[0321] According to a particular embodiment, the invention relates to a process for preparing ethylene glycol as defined above, in which said catalyst has an amount of more than 50 mol% of element copper at an oxidation state (II) in the form of CuO and more than 50% of element cobalt at an oxidation state (II) in the form of CO2O3 or Co(OH)2.

[0322] According to a particular embodiment, the invention relates to a process for preparing ethylene glycol as defined above, in which said catalyst has an amount greater than 70 mol% of element copper at an oxidation state (II) in the form of CuO and an amount greater than 65 mol% of element cobalt at an oxidation state (II) in the form of CO2O3 or CO(OH)2.

[0323] According to a particular embodiment, the invention relates to a process for preparing ethylene glycol as defined above, in which said catalyst has:

[0324] - a quantity of 10 to 30 mol% of copper element in oxidation state (I) in the form of CU2O.

[0325] According to a particular embodiment, the invention relates to a process for preparing ethylene glycol as defined above, in which said catalyst has:

[0326] - a quantity of 10 to 30 mol% of the element copper in the metallic state at an oxidation state (0) or at an oxidation state (I) in the form of CU2O - and a quantity of 10 to 35 mol% of the element cobalt in the metallic state at an oxidation state (0).

[0327] According to a particular embodiment, the invention relates to a process for preparing ethylene glycol as defined above, in which said catalyst has: an amount greater than 70 mol% of element copper at an oxidation state (II) in the form of CuO, an amount of 10 to 30 mol% of element copper at an oxidation state (I) in the form of CU2O and an amount greater than 65 mol% of element cobalt at an oxidation state (II) in the form of CO2O3 or Co(OH)2.

[0328] According to a particular embodiment, the invention relates to a process for preparing ethylene glycol as defined above, in which said catalyst has: an amount greater than 70 mol% of element copper in an oxidation state (II) in the form of CuO, an amount of 10 to 30 mol% of element copper in the metallic state in an oxidation state (0) or in an oxidation state (I) in the form of CU2O an amount of 10 to 35 mol% of element cobalt in the metallic state in an oxidation state (0), and an amount greater than 65 mol% of element cobalt in an oxidation state (II) in the form of CO2O3 or Co(OH)2.

[0329] According to a particular embodiment, the invention relates to a process for preparing ethylene glycol as defined above, in which said catalyst has:

[0330] - a quantity of more than 50 mol% of the element copper in oxidation state (II) and more than 50% of the element cobalt in oxidation state (II),

[0331] - a specific surface area of ​​1 to 50 m 2 / g

[0332] - a crystalline phase, analyzed by X-ray diffraction, crystallized in a monoclinic crystalline system.

[0333] According to a particular embodiment, the invention relates to a process for preparing ethylene glycol as defined above, in which said catalyst has: an amount greater than 70 mol% of element copper at an oxidation state (II) in the form of CuO, an amount of 10 to 30 mol% of element copper in the metallic state at an oxidation state (0) or at an oxidation state (I) in the form of CU2O an amount greater than 65 mol% of element cobalt at an oxidation state (II) in the form of CO2O3 or Co(OH)2. a specific surface area of ​​1 to 50 m 2 / g, especially from 1 to 10 m2 / g analyzed by BET, and a crystalline phase, analyzed by X-ray diffraction, crystallized in a monoclinic crystal system, notably baddeleyite, in particular comprising impurities of Hafnium, Rhenium and Silicon.

[0334] According to a particular embodiment, the invention relates to a process for preparing ethylene glycol as defined above, in which said catalyst has: an amount greater than 70 mol% of element copper in oxidation state (II) in the form of CuO, an amount of 10 to 30 mol% of element copper in the metallic state in oxidation state (0) or in oxidation state (I) in the form of CU2O an amount of 10 to 35 mol% of element cobalt in the metallic state in oxidation state (0), an amount greater than 65 mol% of element cobalt in oxidation state (II) in the form of CO2O3 or Co(OH)2. a specific surface area of ​​1 to 50 m 2 / g, especially from 1 to 10 m 2 / g analyzed by BET, and a crystalline phase, analyzed by X-ray diffraction, crystallized in a monoclinic crystal system, notably baddeleyite, in particular comprising impurities of Hafnium, Rhenium and Silicon.

[0335] According to a particular embodiment, the invention relates to a process for preparing ethylene glycol as defined above, in which said catalyst is in the form of micrometric particles of 1 to 500 pm.

[0336] Conditions of the process for the preparation of ethylene glycol

[0337] According to a particular embodiment, the invention relates to a process for preparing ethylene glycol as defined above, in which said catalyst is used in a proportion of 0.1 to 10 mmol of copper, in particular in a proportion of 4 mmol of Cu.

[0338] The 0.1 to 10 mmol range includes the following ranges: 0.1 to 0.5 mmol, 0.5 to 1 mmol, 1 to 2 mmol, 2 to 3 mmol, 3 to 4 mmol.

[0339] According to a particular embodiment, the invention relates to a process for preparing ethylene glycol as defined above, in which the oxalate compound is used in a proportion of 2 to 400 molar equivalents, in particular in a proportion of 5 equivalents, relative to the metal Cu.

[0340] The range of 2 to 400 molar equivalents (eq.) includes the following ranges: 2 to 3 eq., 3 to 4 eq., 4 to 5 eq., 5 to 10 eq., 10 to 50 eq., 50 to 100 eq., 100 to 200 eq., 200 to 300 eq., 300 to 400 eq.

[0341] According to a particular embodiment, the invention relates to a process for preparing ethylene glycol as defined above, in which the dihydrogen is used under a pressure of 2 to 10 MPa, in particular 5 MPa. The expression MPa corresponds to 10 6Pascal and is equivalent to 10 bars.

[0342] The expression "from 2.0 to 10.0 MPa" corresponds to the ranges: from 2.0 to 2.5 MPa; from 2.5 to 3.0 MPa; from 3.0 to 3.5 MPa; from 3.5 to 4.0 MPa; from 4.0 to 4.5 MPa; from 4.5 to 5.0 MPa; from 5.0 to 5.5 MPa; from 5.5 to 6.0 MPa; from 6.0 to 6.5 MPa; from 6.5 to 7.0 MPa; from 7.0 to 7.5 MPa; from 7.5 to 8.0 MPa; from 8.0 to 8.5 MPa; from 8.5 to 9.0 MPa; from 9.0 to 9.5 MPa; from 9.5 to 10 MPa.

[0343] According to a particular embodiment, the invention relates to a process for preparing ethylene glycol as defined above, in which the solvent is chosen from ethanol, methanol, isopropanol, tetrahydrofuran (THF), 2-methyltetrahydrofuran, toluene and dioxane, in particular ethanol.

[0344] According to a particular embodiment, the invention relates to a process for preparing ethylene glycol as defined above, in which the solvent is ethanol and the oxalate is diethyloxalate.

[0345] According to a particular embodiment, the invention relates to a process for preparing ethylene glycol as defined above, in which the reaction medium is placed under a pressure of 2 to 10 MPa, in particular 5 MPa.

[0346] According to a particular embodiment, the invention relates to a process for preparing ethylene glycol as defined above, in which the reaction medium is heated to a temperature of from 100 to 250°C, in particular from 200 to 220°C.

[0347] The 100 to 250°C range includes the following ranges: 100 to 150°C, 150 to 200°C and 200 to 250°C.

[0348] According to a particular embodiment, the invention relates to a process for preparing ethylene glycol as defined above, in which the reaction medium is heated for 5 to 24 hours, in particular 8 or 16 hours.

[0349] Selectivity and efficiency.

[0350] According to a particular embodiment, the invention relates to a process for preparing ethylene glycol as defined above, in which the hydrogenation reaction of said oxalate compound with hydrogen to obtain ethylene glycol is selective, with a selectivity of more than 70%, in particular more than 80%, preferably more than 90%, preferably greater than or equal to 95%.

[0351] According to a particular embodiment, the invention relates to a process for preparing ethylene glycol as defined above, in which the hydrogenation reaction of said oxalate compound with hydrogen to obtain ethylene glycol has a yield of more than 50%, in particular more than 70%, preferably more than 80%.

[0352] According to a particular embodiment, the invention relates to a process for the preparation as defined above of ethylene glycol, in which the catalyst is recovered at the end of a hydrogenation reaction step and is reused as a catalyst in another catalyzed reaction step.

[0353] According to a particular embodiment, the invention relates to a process for the preparation as defined above of ethylene glycol, in which the catalyst is recovered at the end of a hydrogenation reaction step and is reused as a catalyst in another subsequent hydrogenation reaction step.

[0354] Advantageously, the catalyst recovered at the end of a hydrogenation reaction step can be used during several successive cycles of hydrogenation reaction steps.According to a particular embodiment, the invention relates to a process for preparing ethylene glycol as defined above, in which dihydrogen is used under a pressure of 2 to 10 MPa, in particular 6 MPa, in which the reaction medium is heated to a temperature of 100 to 250°C, in particular 180 to 220°C, optionally in which the reaction medium is heated for 5 to 24 hours, in particular 8 or 16 hours, in which during said step of heating the reaction medium, said bimetallic supported catalyst is activated, said catalyst activity consisting of: 80 to 100%, in particular 95 to 100%, preferably 100%, of the metallic copper atoms at a zero oxidation state Cu(0) and 80 to 100% of the cobalt atoms at an oxidation state greater than zero.

[0355] Advantageously, the embodiments of the process according to the invention do not require prior activation of the catalyst by reduction of the metallic species, the catalyst being activated in situ during the process.

[0356] The catalytic species of the oxalate hydrogenation reaction, namely metallic copper with oxidation state (0), are formed in situ. The second metallic element, cobalt, mainly in oxidized form on the surface of the support, acts as a promoter on the copper for the catalysis of the oxalate hydrogenation reaction. Thus, the bimetallic catalyst based on copper and cobalt can be introduced directly into the oxalate hydrogenation process according to the invention and it does not need to be reduced to metallic form beforehand to initiate the hydrogenation reaction, unlike many bimetallic catalysts of the prior art which are inactive in the absence of a first step of reduction of the catalytic species.

[0357] Flow process conditions

[0358] Without limitation, the method according to the invention can be implemented in a flow chemistry apparatus, for example in commercial reactors such as "H-Cube Pro®" or "Phoenix®" from the company ThalesNano INC. (7 Zahony Street, Graphisoft Park, Building D, H-1031 Budapest, Hungary) or such as the "E-Series" or "R-Series flow chemistry systems" reactors from the company Vapourtec Ltd (Unit 21 / Park Farm Business Centre / Fornham Pk, Bury Saint Edmunds IP28 6TS, United Kingdom).

[0359] Advantageously, the continuous flow process is carried out at a temperature of 100°C to 250°C.

[0360] Advantageously, the continuous flow process is carried out at a pressure of 0.1 MPa to 10 MPa, preferably 5 MPa.

[0361] According to a particular embodiment, the continuous flow process is carried out in a reactor in which the gases represent 10 to 90% of the volume of the reactor.

[0362] The expression "10 to 90%" corresponds to the following ranges: 10 to 20%; 20 to 30%; 30 to 40%; 40 to 50%; 50 to 60%; 60 to 70%; 70 to 80%; 80 to 90%.

[0363] According to a particular embodiment, the continuous flow process is carried out by means allowing a contact time between the reagents of 1 second to 2 hours, in particular of 1 second to 2 minutes.

[0364] The expression "1 second to 2 hours" corresponds to the ranges: from 1 to 15 seconds; from 15 to 30 seconds; from 30 seconds to 1 minute; from 1 to 2 minutes; from 2 to 15 minutes; from 15 to 30 minutes; from 30 minutes to 1 hour; from 1 to 2 hours.

[0365] According to a particular embodiment, the hydrogenation reaction step of the process is carried out in continuous flow and comprises means for introducing into the reactor the flow of hydrogen in contact with the substrate (oxalate).

[0366] According to a particular embodiment, the invention relates to a process for preparing ethylene glycol as defined above, in which the oxalate circulates under flow and / or the dihydrogen circulates under flow, through or in contact with said catalyst.

[0367] Process for preparing the catalyst

[0368] A fourth subject of the invention relates to a process for preparing a CoCu / ZrC>2 catalyst according to the catalyst of the invention as defined above comprising:

[0369] • a step A of impregnation of a cobalt salt and a copper salt, dissolved in an aqueous solution, free of additive and surfactant, in a volume of water of 5 to 10 mL, on a zirconium dioxide support in powder form, with a mass ratio of the solution / mass of support of from 0.6 to 1.0; to obtain the CoCu / ZrC>2 catalyst in the form of a homogeneous mixture, said support having a surface area of ​​1 to 250 m 2 / g, especially from 1 to 75 m 2 / g, especially from 1 to 50 m 2 / g, preferably 1 to 5 m 2 / g and comprising a crystalline phase, analyzed by X-ray diffraction, crystallized in a monoclinic crystalline system,

[0370] • a step B of drying said homogeneous material, at a temperature of 60 to 100°C, for a period of 10 to 24 hours, to obtain the CoCu / ZrC>2 catalyst in the form of a dry homogeneous mixture,

[0371] • an activation step C, comprising calcination in air of said dry homogeneous mixture at a temperature of 200 to 1000°C, for a period of 1 to 15 hours, to obtain said catalyst.

[0372] According to a particular embodiment, the invention relates to a process as defined above for preparing a catalyst according to the invention, in which in step A, said cobalt salt is cobalt nitrate and / or said copper salt is copper nitrate.

[0373] According to a particular embodiment, the invention relates to a process as defined above for preparing a catalyst according to the invention, in which in step A, said support is used in a proportion of 1 to 50 ranges.

[0374] According to a particular embodiment, the invention relates to a process as defined above for preparing a catalyst according to the invention, in which in step A, said support used has a surface area, analyzed by BET, of 1 to 75 m 2 / g.

[0375] According to a particular embodiment, the invention relates to a process as defined above for preparing a catalyst according to the invention, in which in step A, said support used has a surface area, analyzed by BET, of 1 to 50 m 2 / g.

[0376] According to a particular embodiment, the invention relates to a process as defined above for preparing a catalyst according to the invention, in which in step A, said catalyst support used has a surface area, analyzed by BET, of 1 to 10 m 2 / g, preferably 5 to 7 m 2 / g.

[0377] According to a particular embodiment, the invention relates to a process as defined above for preparing a catalyst according to the invention, in which in step A, said support used has a crystalline phase representing from 50 to 90% by total weight of the catalyst. According to a particular embodiment, the invention relates to a process as defined above for preparing a catalyst according to the invention, in which in step A, said support used comprises baddeleyite.

[0378] According to a particular embodiment, the invention relates to a process as defined above for preparing a catalyst according to the invention, in which in step A, said support used comprises baddeleyite whose crystallite size is from 15 to 100 nm, preferably from 15 to 50 nm, and optionally comprising impurities of Hafnium (Hf), Rhenium (Re) and silicon (Si). Advantageously, the mass percentage ratio between Hafnium atoms and zirconium atoms (Hf / Zr) is less than 5% in said support used.

[0379] Advantageously, the mass percentage ratio between Rhenium atoms and zirconium atoms (Re / Zr) is less than 5% in said support used.

[0380] Advantageously, the mass percentage ratio between the silicon atoms and the zirconium atoms (Si / Zr) is less than 2% in said support used.

[0381] Advantageously in said ZrO2 support:

[0382] - the mass percentage ratio between Hafnium atoms and zirconium atoms (Hf / Zr) is less than 5%,

[0383] - the mass percentage ratio between Rhenium atoms and zirconium atoms (Re / Zr) is less than 5%,

[0384] - the mass percentage ratio between Silicon atoms and zirconium atoms (Si / Zr) is less than 2%.

[0385] According to a particular embodiment, the invention relates to a process as defined above for preparing a catalyst according to the invention, in which in step A, the total mass content of the bimetallic elements copper and cobalt is from 0.5 to 25% by total weight of the catalyst.

[0386] According to a particular embodiment, the invention relates to a process as defined above for preparing a catalyst according to the invention, in which in step A, the total mass content of the bimetallic elements copper and cobalt is from 5 to 20% by total weight of the catalyst.

[0387] According to a particular embodiment, the invention relates to a process as defined above for preparing a catalyst according to the invention, in which in step A, the total mass content of the copper element is from 1 to 25% by total weight of the catalyst, preferably from 1 to 10% by total weight of the catalyst.

[0388] According to a particular embodiment, the invention relates to a process as defined above for preparing a catalyst according to the invention, in which in step A, the total mass content of the cobalt element is from 1 to 25% by total weight of the catalyst, preferably from 1 to 10% by total weight of the catalyst.

[0389] According to a particular embodiment, the invention relates to a method as defined above, in which the mass quantity of cobalt is greater than that of copper.

[0390] According to a particular embodiment, the invention relates to a process as defined above, in which in step A, the weight ratio between copper and cobalt varies from 1:1 to 1:10, in particular from 1:1 to 1:5.

[0391] According to a particular embodiment, the invention relates to a process as defined above, in which in step A, the mass composition of cobalt and copper of the catalyst is chosen from Co(10%)Cu(5%) and Co(15%)Cu(5%). According to a particular embodiment, the invention relates to a process as defined above, in which the mass quantity of copper is greater than that of cobalt.

[0392] According to a particular embodiment, the invention relates to a process as defined above for preparing a catalyst according to the invention, in which in step A, the weight ratio between cobalt and copper varies from 1:1 to 1:10.

[0393] According to a particular embodiment, the invention relates to a process as defined above for preparing a catalyst according to the invention, in which in step A, the weight ratio between cobalt and copper varies from 2:10 to 5:10.

[0394] According to a particular embodiment, the invention relates to a process as defined above for preparing a catalyst according to the invention, in which in step A, the support is in the form of micrometric particles of 1 to 500 μm.

[0395] According to a particular embodiment, the invention relates to a process as defined above for preparing a catalyst according to the invention, in which in step B, said homogeneous mixture is dried at 80°C for 16 hours.

[0396] According to a particular embodiment, the invention relates to a process as defined above for preparing a catalyst according to the invention, in which in step C, said dry homogeneous mixture is calcined at 600°C for 2 hours.

[0397] Catalyst prepared according to the process of the invention

[0398] A fifth subject of the present invention relates to a bimetallic supported catalyst comprising copper and cobalt on a zirconium dioxide support, of formula CoCu / ZrC>2, capable of being obtained by the process for preparing a catalyst as defined above.

[0399] Characteristics of the catalyst under reducing atmosphere

[0400] According to a particular embodiment, the invention relates to a bimetallic supported catalyst prepared according to the invention and as defined above, in which said catalyst analyzed by programmed temperature reduction (PTR) carried out in a dihydrogen reducing atmosphere over a temperature range of 30 to 900°C, is characterized by a reduction temperature of the metallic copper of oxidation state (0) in the range of 150 to 250°C, in particular of 180 to 220°C.

[0401] Advantageously, at a temperature higher, in particular at least 10°C, than said reduction temperature of metallic copper, the copper atoms are 80 to 100%, in particular 95 to 100%, preferably 100%, in metallic form. Advantageously, at a temperature higher, in particular at least 10°C, than said reduction temperature of metallic copper, the cobalt atoms are more than 80%, in particular 80 to 100%, preferably 100% in oxidized form, i.e. at an oxidation state higher than zero.

[0402] Advantageously, at a temperature higher, in particular by at least 10°C, than said reduction temperature of metallic copper, the cobalt atoms are from 0 to 20%, in particular from 0 to 10%, preferably less than 5%, in metallic form at a zero oxidation state.

[0403] According to a particular embodiment, the invention relates to a bimetallic supported catalyst as defined above, wherein said catalyst analyzed by programmed temperature reduction (PTR) carried out in a dihydrogen reducing atmosphere over a temperature range of 30 to 900°C, is characterized by a reduction temperature of the metallic copper of oxidation state (0) in the range of 150 to 250°C, in particular at a temperature higher than at least 10°C of said reduction temperature of the metallic copper analyzed by PTR, the copper atoms are 80 to 100%, preferably 100% in metallic form, the cobalt atoms are 80 to 100%, preferably 100% in oxidized form.

[0404] According to a particular embodiment, the invention relates to a bimetallic supported catalyst as defined above, wherein said catalyst analyzed by programmed temperature reduction (PTR) carried out at a reducing atmosphere under a flow of 5 vol. % H2 in Argon, in particular at 30 mL / min, over a temperature range of 30 to 900°C, in particular with a heating rate of 5°C / min, is characterized by a reduction temperature of metallic copper of oxidation state (0) in the range of 150 to 250°C.

[0405] Advantageously, the catalyst is pretreated under an inert atmosphere before said analysis, in particular at 200°C under Helium.

[0406] According to a particular embodiment, the invention relates to a bimetallic supported catalyst as defined above, in which said catalyst under reduced atmosphere comprising dihydrogen at a pressure of 2 to 10 MPa and at a temperature of 150 to 250°C, in particular 180 to 220°C, comprises:

[0407] - from 80 to 100%, in particular 95 to 100%, preferably 100%, of the metallic copper atoms Cu(0) and

[0408] - from 80 to 100% of the cobalt atoms in an oxidation state greater than zero. Advantageously, the copper atoms are 95%, preferably 100% in metallic form.

[0409] Advantageously, the cobalt atoms are 80 to 100%, in particular 95 to 100%, preferably 100%, in oxidized form to an oxidation state greater than zero.

[0410] Advantageously, the cobalt atoms are from 0 to 20%, in particular from 0 to 15%, preferably less than 20%, in metallic form.

[0411] Catalyst in activated form

[0412] Another subject of the present invention relates to an activated bimetallic supported catalyst, comprising at the surface copper and cobalt, on a zirconium dioxide support, of formula CuCo / ZrC>2, in which the copper atoms are 80 to 100%, in particular 95 to 100%, preferably 100%, at a zero oxidation state Cu(0) and the cobalt atoms are 80 to 100%, in particular 95 to 100%, preferably 100%, at an oxidation state greater than zero.

[0413] The term "activated catalyst" means the catalyst in its activated form, i.e. its form during the chemical reaction catalyzed by this catalyst, namely a form which includes the catalytic species at the origin of the catalysis.

[0414] Use of the catalyst for the hydrogenolysis of ethylene glycol or for depolymerizing biomass

[0415] Another object of the present invention relates to the use of a CoCu / ZrC>2 catalyst according to the invention as defined above, for the hydrogenolysis of ethylene glycol.

[0416] The inventors have surprisingly observed that after the hydrogenation reaction of oxalates to ethylene glycol, when the oxalate is no longer present as a substrate in the medium, prolonged contact of ethylene glycol with the CoCu / ZrC>2 catalyst according to the invention leads to hydrogenolysis of ethylene glycol. Advantageously, the hydrogenation reaction of oxalate to ethylene glycol and the hydrogenolysis reaction of ethylene glycol are subsequent and can be separated.

[0417] For the purposes of the present invention, the term "hydrogenolysis" means the cleavage reaction of at least one carbon-carbon CC or carbon-heteroatom covalent bond such as the carbon-oxygen bond, by the action of hydrogen.

[0418] Another subject of the present invention relates to a process for the hydrogenolysis of ethylene glycol comprising: o a step of bringing ethylene glycol into contact in the presence of hydrogen and a heterogeneous bimetallic supported catalyst comprising copper and cobalt on a zirconium dioxide support, of formula CoCu / ZrC>2 as defined above.

[0419] According to a particular embodiment, the invention relates to a process for the hydrogenolysis of ethylene glycol as defined above, comprising: o bringing into contact: ethylene glycol, dihydrogen, in particular from 20 to 100 bars, preferably at 60 bars, said supported catalyst of formula CoCu / ZrC>2, comprising cobalt and copper on a zirconium dioxide support, optionally a solvent, in particular tetrahydrofuran (THF), optionally a base, in particular potassium tert-butylate (KOtBu), to obtain a reaction medium optionally pressurized, o optionally heating said reaction medium, to obtain a degradation of ethylene glycol by cleavage of at least one carbon-carbon or carbon-oxygen covalent bond.

[0420] Another object of the present invention relates to the use of a CoCu / ZrC>2 catalyst according to the invention as defined above for depolymerizing biomass.

[0421] According to a particular embodiment, the invention relates to the use of a CoCu / ZrC>2 catalyst as defined above for depolymerizing biomass by hydrogenolysis of the ethylene glycol groups present in the compounds constituting said biomass.

[0422] The inventors surprisingly observed that the CoCu / ZrO2 catalyst according to the invention could catalyze the hydrogenolysis reaction of the diol groups present in the carbohydrate molecules contained in the biomass by cleaving the carbon-carbon CC or carbon-oxygen CO bonds.

[0423] For the purposes of the present invention, the term "biomass" means organic matter of plant origin (including microalgae), animal, bacterial or fungal origin (fungi), usable as a source of energy (bioenergy). Biomass includes in particular carbohydrate molecules or polyols, in which diol groups -CHOH- CHOH- are present, containing covalent bonds CC and CO. For the purposes of the present invention, the term "depolymerizing biomass" means the action of cleaving covalent carbon-carbon bonds CC or carbon-heteroatom CX such as the carbon-oxygen bond CO, of the carbohydrate molecules contained in the biomass.

[0424] Another subject of the invention relates to a process for degrading biomass comprising: o a step of hydrogenolysis of the CC and C-O bonds in the diol groups contained in the carbohydrate molecules contained in the biomass, in the presence of a bimetallic supported catalyst comprising copper and cobalt on a zirconium dioxide support, of formula CoCu / ZrO2 as defined above.

[0425] The following examples and figures illustrate the invention, without limiting its scope.

[0426] Figure 1 represents the X-ray powder diffractogram of a Cu(10%)Co(5%) / ZrO2(A) catalyst, with a specific surface area of ​​approximately 5m 2 / g prepared with a ZrO2(A) support.

[0427] Figure 2 represents the X-ray powder diffractogram of a ZrO2(A) support which was calcined at 600°C for 2 hours.

[0428] Figure 3 represents the X-ray powder diffractogram of a Cu(10%)Co(5%) / ZrO2(B) catalyst, with a specific surface area of ​​59 m 2 / g.

[0429] Figure 4 shows scanning electron microscopy images of a Cu(10%)Co(5%) / ZrC>2(A) catalyst, with a specific surface area of ​​approximately 5 m 2 / g, calcined at 600°C for 2 hours

[0430] Figure 5 shows scanning electron microscopy images of a ZrC>2(A) support calcined at 600°C for 2 hours.

[0431] Figure 6 shows scanning electron microscopy images of a Cu(10%)Co(5%) / ZrC>2(B) catalyst, with a specific surface area of ​​59 m 2 / g, calcined at 600°C for 2 hours, Figure 7 represents the X-ray photoelectron spectrometry spectrum of a Cu-Co / ZrC>2(A) catalyst, calcined at 600°C for 2 hours, with a composition of Cu at 10% and Co at 5% by weight relative to the total weight of the catalyst (spectrum A) and the X-ray photoelectron spectrometry spectrum of the support used ZrC>2(A) for the preparation of said catalyst calcined at 600°C for 2 hours (spectrum B).

[0432] Figure 8 is a histogram of ethylene glycol (EG) yields from tests conducted with monometallic copper or cobalt catalysts, bimetallic copper and cobalt catalysts, and catalyst and support mixtures.

[0433] Figure 9 is a histogram of ethylene glycol (EG) yields from tests conducted with 10% copper monometallic catalysts, copper and cobalt bimetallic catalysts at a constant 10% copper content and a variable cobalt content from 1 to 10%.

[0434] Figure 10 represents the temperature programmed reduction analysis curve under dihydrogen flow (H2-TRP) of the catalysts for the prepared Cu(10%)Co(5%) / ZrC>2 catalyst in the temperature range of 100 to 500°C.

[0435] Example 1 - Materials and methods

[0436] Two zirconium dioxide supports ZrC>2(A) and ZrC>2(B) with different specific surface areas, respectively 5 to 7 m 2 / g for ZrC>2(A ) and 85 m 2 / g for ZrC>2(B), were used for the preparation of the catalysts.

[0437] The zirconium dioxide support ZrC>2, called ZrC>2(A), having a specific surface area of ​​5 to 7 m2 / g is supplied by Sterm Chemicals (15 Rue de l'Atome, 67800 Bischheim) with reference number 93-4013.

[0438] The zirconium dioxide carrier ZrC>2(A) supplied by Sterm Chemicals comprises by weight approximately 97% zirconium dioxide, 1.86% Hafnium dioxide (HfC>2) and traces of silica (SiC>2) and Yttrium oxide (Y2O3).

[0439] The zirconium dioxide support ZrC>2, called ZrC>2(B), having a specific surface area greater than 85 m 2 / g is supplied by Thermo Fisher Scientific (formerly Alfa Aesar) under product number AA4381522.

[0440] The Y-AI2O3 supports are supplied by Strem Chemicals (15 Rue de l'Atome, 67800 Bischheim) under reference 13-2525.

[0441] The SiC>2 support (40-63 mm) was supplied by VWR chemicals with reference 154425P.

[0442] Cobalt nitrate (Co(NC>3)2.3H2O) and copper nitrate Cu(NC>3)2.3H2O were supplied by Fischer.

[0443] The autoclave is supplied by Parr Instrument Company.

[0444] Example 2 - General procedure for the preparation of heterogeneous Co / ZrC>2 catalysts

[0445] Cobalt nitrate Co(NC>3)2.6H2O was dissolved in a minimum volume of deionized water, 5 to 10 mL, forming a solution. This solution containing the metal precursors was added to the appropriate amount of zirconium dioxide support ZrC>2(A) (having 5 to 7 m 2 / g of specific surface area measured by BET) and the resulting paste of ZrC>2 was mixed at room temperature until a homogeneous material was obtained. The material was then dried at 80°C for 16 hours, and then calcined at 600°C in air for 2 hours to obtain the catalyst.

[0446] Example 3- General procedure for the preparation of heterogeneous Cu / ZrC>2 catalysts

[0447] Copper nitrate Cu(NOs)2.3H2O Cu(NOs)2.3H2O was dissolved in a minimum volume of deionized water, 5 to 10 mL, forming a solution. This solution containing the metal precursors was added to the appropriate amount of zirconium dioxide support ZrC>2(A) (having 5 to 7 m 2 / g of specific surface area measured by BET) and the resulting paste of ZrC>2 was mixed at room temperature until a homogeneous material was obtained. The material was then dried at 80°C for 16 hours, and then calcined at 600°C in air for 2 hours to obtain the catalyst.

[0448] Example 4- General procedure for the preparation of heterogeneous Cu-Co / ZrO2(A) catalysts

[0449] Cobalt nitrate Co(NC>3)2.6H2O and copper nitrate Cu(NC>3)2.3H2O were dissolved in a minimum volume of deionized water, 5 to 10 mL forming a solution. This solution containing the metal precursors was added to the appropriate amount of ZrC>2(A) support with a specific surface area of ​​5 to 7 m 2 / g, and was mixed at room temperature until a homogeneous material was obtained. The material was then dried at 80°C for 16 h, and then calcined at 600°C in air for 2 h to obtain the catalyst.

[0450] Example 5 - Preparation of heterogeneous mono- and bimetallic catalysts Co / ZrC>2, Cu / ZrO2, Cu-Co / ZrC>2 in which zirconium dioxide has a specific surface area of ​​5 to 7 m 2 / g.

[0451] Table 1 below reports the preparation conditions of the Co / ZrC>2, Cu / ZrC>2 and Cu-Co / ZrC>2 catalysts prepared according to examples 2, 3 and 4 with a support.

[0452]

[0453] Table 1: Co / ZrC>2, Cu / ZrC>2 and Cu-Co / ZrC>2 catalysts prepared with ZrC>2(A) having a specific surface area of ​​5 to 7 m 2 / g.

[0454] Example 6 - General procedure for the preparation of heterogeneous Cu-Co / Support catalysts

[0455] Cobalt nitrate Co(NC>3)2.6H2O and copper nitrate Cu(NOs)2.3H2O were dissolved in a minimum volume of demineralized water, 5 to 10 mL forming a solution. This solution containing the metal precursors was added to the appropriate amount of support (ZrC>2(B) with a specific surface area greater than 85 m 2 / g, SiC>2, CeC>2 or Y-AI2O3) and was mixed at room temperature until a homogeneous material was obtained. The material was then dried at 80°C for 16 h and then calcined at 600°C in air for 2 h to obtain the catalyst.

[0456] Table 2 below reports the preparation conditions of a Cu-Co / Support catalyst prepared according to Example 6.

[0457] Table 2: Co-Cu / Support catalyst prepared with various supports.

[0458] Example 7 - General procedure for heterogeneous catalysis of the hydrogenation of dialkyl oxalates in a 450 mL reactor.

[0459] In a 450 mL Parr autoclave equipped with a magnetic stirrer, a heterogeneous copper-based (4 mmol Cu) or copper-based (4 mmol Cu) and cobalt-based or cobalt-based (4 mmol Co) catalyst, diethyl oxalate (20 mmol) and ethanol (50 mL) as solvent were introduced. The reactor was sealed, and the reaction mixture was purged three times with nitrogen (5 bar) and twice with hydrogen (5 bar).

[0460] The autoclave was then pressurized with 50 bars of hydrogen. The reaction medium was then brought under stirring to 200°C for 16 hours or to 220°C for 8 hours.

[0461] Once the reaction was complete, the autoclave was brought back to room temperature before being depressurized and purged three times with nitrogen (5 bars).

[0462] The final mixture obtained was diluted in ethanol or methanol and then an internal standard was added (mesitylene), to calculate the yield using GC-MS.

[0463] Example 8 - Tests carried out with the catalysts Cu / ZrO2(A), Co / ZrO2(A) and CoCu / ZrC>2(A). Table 3 reports the conditions of the hydrogenation tests respectively with a Cu / ZrO2(A), Co / ZrO2(A) or CoCu / ZrC>2(A) catalyst prepared according to Example 5, as well as the yield (Yield) and selectivity (selec). The hydrogenation yield and selectivity are calculated using GC-MS, mesitylene is used as an internal standard.

[0464] Table 3: Conditions of hydrogenation tests with a Cu / ZrO2(A), Co / ZrO2(A) or CoCu / ZrC>2(A) catalyst and the results obtained.

[0465] Example 9 - Tests carried out with CoCu catalysts on various supports prepared according to Example 6. Table 4 reports the conditions of the hydrogenation tests respectively with a CoCu catalyst on various supports, prepared according to Example 6, as well as the yield (Yield) and the selectivity (selec). The hydrogenation yield and the selectivity are calculated using GC-MS, mesitylene is used as an internal standard.

[0466] Table 4: Conditions of hydrogenation tests with a CoCu catalyst on various supports and the results obtained.

[0467] Example 10 - General Procedure for Heterogeneous Catalysis of the Hydrogenation of Diethyl Oxalates in a 1 Liter Reactor

[0468] A 1-liter Parr autoclave equipped with a magnetic stirrer was introduced into a heterogeneous copper catalyst (40 mmol Cu), diethyl oxalate (200 mmol), and ethanol (400 mL) as solvent. The reactor was sealed, and the reaction mixture was purged three times with nitrogen (5 bar) and twice with hydrogen (5 bar).

[0469] The autoclave was then pressurized with 50 bars of hydrogen. The reaction medium was then brought under stirring to 200°C for 16 hours or 220°C for 8 hours.

[0470] Once the reaction was complete, the autoclave was brought back to room temperature before being depressurized and purged three times with nitrogen (5 bars).

[0471] Ethylene glycol was recovered after purification by vacuum distillation at 120°C / 5 mbar.

[0472] Example 11. Tests carried out with the CoCu / ZrO2(A) catalyst in a 1 liter reactor

[0473] Table 5 reports the conditions of the hydrogenation tests of an oxalate, diethyloxalate (DEO) with a CoCu / ZrO2(A) catalyst carried out in a 1 liter reactor according to example 11, as well as the yield (Yield). The yield of ethylene glycol formed at the end of the hydrogenation step is calculated using GC-MS, mesitylene is used as an internal standard.

[0474] Table 5: Conditions of hydrogenation tests with a CoCu / ZrO2(A) catalyst in a 1 liter reactor and the results obtained.

[0475] Example 12 - General Procedure for Catalyst Recycling after Hydrogenation of Dialkyl Oxalates.

[0476] After a hydrogenation reaction of dialkyl oxalates, the catalyst Co(5%)Cu(10%) / ZrC>2 (A) is separated from the liquid reaction medium by filtration. The catalyst is then washed 3 x 25 mL of ethanol and centrifuged. The material was then dried at 80°C for 4 h before being used again in a hydrogenation reaction of dialkyl oxalates under the same conditions as reaction 7 in Table 3.

[0477] Example 13 - Catalyst recycling tests after the hydrogenation of dialkyl oxalates. Table 6 below reports the recycling results according to Example 12.

[0478] Table 6: Yield and selectivity of a recycled catalyst

[0479] Example 14 - BET analyses of Cu-Co / ZrC>2 catalysts Table 7 below shows the average specific surface area, analyzed by BET, of Cu(10%)-Co(5%) / ZrO2 catalysts prepared with various zirconium dioxide supports, after calcination at 600°C for 2 hours.

[0480] Table 7: Average specific surface area by BET of Cu-Co / ZrO2 catalysts after calcination.

[0481] Example 15: Structural analysis

[0482] A. Phase analysis

[0483] The X-ray powder diffractograms of the materials (catalysts or support) were carried out with a MINI FLEX II diffractometer from Rigaku, whose X-ray radiation was emitted via a tube and a copper source (wavelength Ko 1.54 Å).

[0484] Figure 1 shows the X-ray diffractogram obtained for the Co(5%)Cu(10%) / ZrC>2 catalyst

[0485] (A) calcined at 600°C for 2 hours, exhibiting a specific surface area of ​​5.4 m2 / g.

[0486] Figure 2 shows the X-ray diffractogram obtained for the ZrC>2(A) support used calcined at 600°C for 2 hours, presenting a specific surface area of ​​6.1 m 2 / g.

[0487] Figure 3 shows the X-ray diffractogram obtained for the Co(5%)Cu(10%) / ZrO2 catalyst

[0488] (B) calcined at 600°C for 2 hours, exhibiting a specific surface area of ​​59 m 2 / g.

[0489] The results of the exploitation of the different diffractograms obtained are presented in tables 8 to 10 below, respectively for: the catalyst Co(5%)Cu(10%) / ZrC>2 (A) in table 8, the support ZrC>2 (A) in table 9 the catalyst Co(5%)Cu(10%) / ZrC>2 (B) in table 10

[0490] Table 8: Phase analysis in the Co(5%)Cu(10%) / ZrC>2 catalyst (A)

[0491] Table 9: Phase analysis in the calcined support ZrC>2 (A)

[0492] Table 10: Phase analysis in the Co(5%)Cu(10%) / ZrC>2 catalyst (B)

[0493] The diffractograms show the presence of crystallized phases.

[0494] XRD analyses indicate that the Baddeleyite crystalline phase (ZrC>2) is present in the catalyzed ZrO2(A), Co(5%)Cu(10%) / ZrO2(A) and Co(5%)Cu(10%) / ZrO2(B) samples.

[0495] The diffractogram of the Co(5%)Cu(10%) / ZrC>2(A) sample reveals the presence of two additional crystalline phases of Copper (I) oxide, CU2O, and Copper (II) oxide, CuO with a weak signature.

[0496] The diffractogram of the Co(5%)Cu(10%) / ZrC>2(B) sample reveals the presence of two additional crystalline phases of Cobalt oxides, CoO and CO3O4 with low intensity.

[0497] B. Crystallinity - Microstructure: Analysis of crystallite size

[0498] Crystallite size

[0499] The crystallinity of materials is characterized by the size of the crystallites.

[0500] The crystallite size was qualitatively estimated in order to compare the different ZrC>2 supports of the catalysts.

[0501] The crystallite size was evaluated according to the following Scherrer formula:

[0502] [Math 2] t - t = crystallite size

[0503] H. cos O k = correction factor = 0.89

[0504] X = wavelength of the source H = width at half-maximum of the peak (in radians) e = diffraction angle

[0505] The width at half maximum was estimated using ImageJ processing software (developed by the National Institutes of Health).

[0506] The crystallite size calculations from the diffractograms of the Co(5%)Cu(10%) / ZrC>2(A) and Co(5%)Cu(10%) / ZrC>2(B) catalysts are reported in the following table 11:

[0507] Table 11: Crystallite sizes

[0508] The ZrC>2(B) support used to prepare Co(5%)Cu(10%) / ZrC>2(B) is a commercial ZrC>2 oxide powder from Alfa Aesar, exhibiting a pore volume of 0.27 cc / g with a specific surface area of ​​more than 85 m 2 / g (BET).

[0509] Small size values, especially those 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 pm.

[0510] The results indicate that the catalyst prepared with the Sterm ZrC>2(A) support according to the invention and the catalysts prepared with the Alfa Aesar ZrC>2(B) support according to the invention have crystallite sizes of 21 nm and 9 nm respectively. Thus, the Cat A and Cat B catalysts are distinguished by the microstructure of the ZrC>2 support.

[0511] In addition to the characteristic related to the specific surface, these results show that the supports of the Cat A and Cat B catalysts of the invention are different in their microstructure.

[0512] Example 16: Morphological analysis

[0513] The SEM images in Figures 4 to 6 were taken using a Zeiss pressure-controlled SEM-FEG scanning microscope, making it possible to observe materials with little or no conductivity without specific preparation.

[0514] The sample was stabilized on carbon adhesive paper to allow SEM observation. It should therefore be noted that the content of the carbon element may be associated with the use of the latter. The results of SEM observations and EDX analyses are presented in summary form below.

[0515] Catalyst Co(5%)Cu(10%) / ZrO2( / )

[0516] The observations of the SEM images in Figure 4 reveal the presence of a population of particles with a rounded morphology. These particles are composed mainly of Zirconium (Zr), Copper (Cu), Oxygen (O), Carbon (C) and Cobalt (Co), with a minor amount of Hafnium (Hf), Rhenium (Re) with traces of Silicon (Si). Quantification was carried out by analysis of the EDX spectrum on an area of ​​these particles. The results expressed in mass percentage are shown in Table 12. Table 12: Chemical composition of the catalyst Co(5%)Cu(10%) / ZrC>2(A)

[0517] Calcined ZrO2(A) support

[0518] SEM observations of the images in Figure 5 reveal the presence of several particle populations (rounded, spherical and angular morphologies). The majority population has a rounded morphology, similar to that of the Co(5%)Cu(10%)ZrC>2 sample. These particles are composed mainly of Zirconium (Zr), Oxygen (O) and Carbon (C) with traces of Rhenium (Re), Hafnium (Hf) and Silicon (Si).

[0519] The secondary population presenting a spherical morphology is composed mainly of Zirconium (Zr), Oxygen (O) and Carbon (C), with a minor amount of Hafnium (Hf) and Rhenium (Re) with traces of Silicon (Si).

[0520] Quantification was performed by EDX spectrum analysis on two areas of the support particles calcined at 600°C for two hours. The results expressed as mass percentage are shown in Table 13.

[0521] Table 13: Chemical composition of the ZrC>2(A) support

[0522] Co(5%)Cu(10%) / ZrO2(B) Catalyst SEM observations of the images in Figure 6 reveal the presence of macroscopic particles with a polyhedral morphology consisting of smaller particles with a rounded morphology. The particles are mainly composed of Zirconium (Zr), Copper (Cu), Cobalt (Co) and Oxygen (O) and to a lesser extent Carbon (C).

[0523] Quantification was performed by EDX spectrum analysis on an area of ​​these particles. The results expressed as mass percentage are shown in Table 14.

[0524] Table 14: Chemical composition of the catalyst Co(5%)Cu(10%) / ZrC>2(B)

[0525] Example 17: Surface analysis by XPS The analyses are carried out with a PHI QUANTES photoemission spectrometer. This device is equipped with a monochromated X-ray source (Ko line of aluminum) as well as a chrome X-ray source allowing Hard XPS, a charge neutralization system for electrically insulating samples and a hemispherical electron analyzer.

[0526] XPS analyses were performed on the Co(5%)Cu(10%) / ZrC>2(A) catalyst calcined at 600°C for 2 hours and a sample of the ZrC>2(A) support also calcined at 600°C for 2 hours.

[0527] The XPS spectra are shown in Figure 7.

[0528] The quantification of the extreme surface, expressed as a mass percentage, on the two samples is presented in Table 15 below:

[0529] Table 15: Chemical composition by XPS

[0530] Both samples have low carbon levels, mainly from air pollution.

[0531] Sample 22 Co(5wt%)Cu(10wt%)ZrC>2 consists of Zirconium (Zr), Oxygen (O), Copper (Cu), Cobalt (Co) with traces of Silicon (Si) and Sodium (Na).

[0532] The ZrO2 sample is composed of Zirconium (Zr) and Oxygen (O) with traces of Silicon (Si) and Sodium (Na).

[0533] Determination of chemical environments

[0534] The results of the Gaussian deconvolutions of the spectra are presented in Table 16 below:

[0535] Table 16: Results of XPS analyses

[0536] C1s spectra:

[0537] For all samples, the deconvolution of the C1s carbon spectra presents 2 components:

[0538] - The majority component at 285.0 eV is characteristic of CC and CH bonds. These bonds come from atmospheric pollution.

[0539] - The component at 288.40 eV is characteristic of C-O and C=O bonds. These bonds are also representative of surface pollution. O1s spectra:

[0540] For all samples, the deconvolution of the oxygen O1s spectra presents 2 components:

[0541] - The majority component at 531.0 eV is characteristic of oxides in general.

[0542] - The component at 531.2 eV is characteristic of transition metal oxides. Si2p spectra:

[0543] For all samples, the deconvolution of the Silicon Si2p spectra presents 2 components:

[0544] - The majority component at 103.3 eV is characteristic of silicon oxides SiOx. - The component at 102.0 eV is characteristic of silicon oxide SiC>2.

[0545] It should be noted that the characteristic component of Cobalt (II) oxide CoO is at the same energy as the component corresponding to SiOx.

[0546] Na 1s spectra:

[0547] For all samples, the deconvolution of the Sodium Nais spectra presents a single component characteristic of atmospheric pollution.

[0548] Cu2p3 / 2 spectrum:

[0549] For the sample Co(5wt%)Cu(10wt%)ZrC>2, the deconvolution of the spectrum of Copper 2p3 / 2 presents 2 components:

[0550] - The majority component at 934.0 eV is characteristic of Copper (II) Oxide CuO.

[0551] The two strong satellite components at 943.5 eV and 963.5 eV are characteristic of Cu ions 2+and therefore Copper (II) oxide CuO.

[0552] - The component at 932.6 eV is characteristic of metallic copper or copper (I) oxide Cu2O.

[0553] Co2p3 / 2 spectrum:

[0554] For the sample Co(5%)Cu(10%)ZrO2, the spectrum of Cobalt 2p3 / 2 shows the characteristic components of Cobalt (III) oxide CO2O3 and Cobalt (II) oxide CoO as well as Cobalt (II) hydroxide Co(OH)2.

[0555] High-resolution XPS spectra of Zirconium 3d5 / 2

[0556] XPS analyses reveal for all samples the majority presence of Zirconium oxide (ZrO2), with traces of Silicon oxides (SiO2 and SiOx) as well as the presence of surface pollution (Carbon and Sodium).

[0557] The Co(5%)Cu(10%) / ZrO2 sample shows the additional presence of Copper in two oxidized forms: CuO and CU2O. XPS analyses also reveal the presence of Cobalt for this sample in the form of Cobalt hydroxide Co(OH)2 or Cobalt (II) oxide CoO or Cobalt (III) oxide CO2O3.

[0558] Example 18 - Continuous Flow Hydrogenation Procedure

[0559] A solution of diethyl oxalate between 0.05 and 0.5 M in ethanol is pumped into the reactor at a flow rate between 0.3 and 3 mL / min. Then, the system pressure is set between 30 and 100 bar using a pressure relief valve, and the reactor is heated to between 150 and 220 °C. The reactor consists of a stainless steel tube containing the catalyst used for the reaction (between 150 and 700 mg). Finally, hydrogen - produced in situ in the equipment or introduced from outside via a valve - is injected into the system at the desired flow rate between 20 and 100 mL / min. Optionally, the catalyst is previously brought into contact with the hydrogen flow before introducing the reagents. Once the system has stabilized, the product is collected at the reactor outlet in vials before being analyzed by GC-MS.

[0560] Example 19 - Procedure for the degradation of ethylene glycol by reduction under hydrogen in the presence of the CuCo / ZrO2 catalyst

[0561] A 450 mL Parr autoclave equipped with a magnetic stirrer was introduced with a heterogeneous copper (4 mmol Cu) and cobalt catalyst, ethylene glycol (10 mmol), a base, potassium tert-butoxide (KOtBu), and tetrahydrofuran (THF) (75 mL) as solvent. The reactor was sealed, and the reaction mixture was purged three times with nitrogen (5 bar) and twice with hydrogen (5 bar).

[0562] The autoclave was then pressurized with 60 bars of hydrogen. The reaction medium was then brought under stirring from 180 to 200°C for 15 hours.

[0563] Once the reaction was complete, the autoclave was brought back to room temperature before being depressurized and purged three times with nitrogen (5 bars).

[0564] The final mixture obtained was diluted and then an internal standard was added (mesitylene), to calculate the conversion of ethylene glycol using GC-MS.

[0565] The balance of the ethylene glycol degradation reaction by hydrogenation in the presence of the CuCo / ZrO2 catalyst is written as follows:

[0566] H2(60 bar) Alcohol / Alkane / Alkene / Ether

[0567] 10 nwnol

[0568] Example 20 - Tests carried out with the CoCu / ZrO2(A) catalyst.

[0569] Table 17 reports the conditions of the ethylene glycol degradation tests by hydrogenation in the presence of a CoCu / ZrO2(A) catalyst prepared according to Example 5. The conversion of ethylene glycol is calculated using GC-MS, mesitylene is used as an internal standard.

[0570] Table 17: Conditions of ethylene glycol hydrogenation tests in the presence of a CoCu / ZrO2(A) catalyst and the results obtained

[0571] Example 21: Synergistic and promoting effect of cobalt on zirconium dioxide supported copper catalysts in the oxalate hydrogenation reaction for the preparation of ethylene glycol.

[0572] Test / s with a mixture

[0573] Test CUCOMIX01 was prepared according to the conditions of tests A-2 and A-1 of example 7, with as catalytic material an equimolar mixture of the two monometallic catalysts Co(5%) / ZrC>2 and Cu(10%) / ZrC>2 with a hydrogenation reaction time of 10 hours instead of 16 hours.

[0574] Test CUCMIX02 was prepared according to the conditions of test A-7 of example 7 with the additional addition of support material (ZrC>2) and with a reaction time of 10 hours instead of 16 hours.

[0575] Table 18 below reports the results of substrate (oxalate) conversion rate, ethylene glycol yield and selectivity towards ethylene glycol production of oxalate hydrogenation tests under similar conditions (temperature, pressure, temp) in the presence of:

[0576] - a monometallic supported catalyst of cobalt or nickel (tests A-1, A-2 and A-3) or

[0577] - a mixture of the two monometallic catalysts (test CU COM 1X01), or

[0578] - a mixture of a bimetallic catalyst with an equivalent quantity by mass of support (zirconium dioxide) or - a bimetallic catalyst based on copper and cobalt, at a constant copper content, namely at a copper content of 10% by total weight of the catalyst (tests A-6 and A-7).

[0579] Table 18: Results obtained from oxalate conversion, EG yield and EG selectivity of oxalate hydrogenation tests in the presence of a copper and / or cobalt catalyst on a zirconium dioxide support.

[0580] For the hydrogenation reaction of oxalate to ethylene glycol (EG), the results of the test series in Table 18 and Figure 8 show that:

[0581] 1) Monometallic cobalt catalysts on zirconium dioxide support are inactive. Catalysts with two cobalt contents were tested, namely Co(5%)ZrO2 and Co(10%)ZrO2 and gave the same results: cobalt supported on zirconium dioxide does not show catalytic activity after 16 hours of reaction

[0582] 2) Monometallic catalysts based on copper supported on zirconium dioxide are active but the yield of ethylene glycol is low (12%) even after 16 hours of reaction for the Cu(10%) / ZrO2 catalyst.

[0583] 3) Bimetallic catalysts based on copper at a content of 10% and cobalt on zirconium dioxide, namely Co(5%)Cu(10%) / ZrO2 and Co(10%)Cu(10%) / ZrO2, are more active than the monometallic catalyst based on copper Cu(10%) / ZrO2. This alone allows proving the promoting effect of the presence of cobalt which has been shown to be inactive at these percentages (5% and 10%) in the absence of copper.

[0584] 4) The mixture of monometallic catalysts Co(5%) / ZrO2 + Cu(10%) / ZrO2 is more active than the bimetallic catalyst Co(5%)Cu(10%)ZrO2, demonstrating a synergy between cobalt and copper, which would be due to the promoting effect of cobalt which allows to modulate the catalytic activity of copper supported on zirconium dioxide.

[0585] Example 22: Effect of cobalt content on zirconium dioxide supported copper-cobalt bimetallic catalysts in the oxalate hydrogenation reaction for the preparation of ethylene glycol.

[0586] Table 19 below reports the results of the conversion rate of the substrate (oxalate), the yield of ethylene glycol and the selectivity towards the production of ethylene glycol from the hydrogenation tests of oxalate under similar conditions (temperature, pressure, time) in the presence of a supported copper-based catalyst, at a constant copper level, namely at a copper content of 10% by total weight of the catalyst, in the absence of cobalt and in the presence of a variable cobalt content of 1% to 10% by total weight of the catalyst.

[0587] Table 19: Results obtained from oxalate conversion, EG yield and EG selectivity of oxalate hydrogenation tests in the presence of a copper-based catalyst with a constant content of 10%n in the absence and presence of a cobalt content of 1 to 10% on zirconium dioxide support.

[0588] For the hydrogenation reaction of oxalate to ethylene glycol (EG), the results of the test series in Table 19 and Figure 9 show that:

[0589] 5) cobalt as a reaction promoter increases the catalytic activity of CoCu / ZrO2 catalysts, showing a peak at 5% cobalt percentage, and a decrease in activity when the cobalt percentage is 10%, a typical behavior expected from promoter effects.

[0590] It is concluded that cobalt has a promoting function in CuCo / ZrO2 catalysts.

[0591] Example 23: Analysis of the CuCo / ZrC>2 catalyst by temperature-programmed reduction.

[0592] Materials and methods

[0593] Temperature-programmed reduction (TPR) or (TRP) analysis is used to characterize solid materials, including metal oxides (nature of the oxide, oxide mixture, dispersion on a support). This analysis technique under a reducing atmosphere is known to those skilled in the art for characterizing heterogeneous catalysts.

[0594] It consists of determining the quantity of dihydrogen consumed as a function of temperature. It makes it possible to determine the temperatures at which the reductions of oxidized forms to metallic forms occur and possibly the nature of the metallic oxides and the ratio between the metallic oxides present.

[0595] Hydrogen temperature programmed reduction (H2-TPR) measurements were performed on a Micromeritics Autochem II 2920 analyzer.

[0596] In a typical experiment, 50 mg of sample was pretreated at 200 °C (heating rate = 10 °C / min) for 30 min under a flow of Helium (He) (30 mL / min). Then, the sample was cooled to 30 °C, maintaining the flow of He. The reduction analysis was carried out from 30 °C to 900 °C (heating rate = 5 °C / min) under a flow of 5 vol. % H2 in Argon (30 mL / min). The final temperature (900 °C) was maintained for 30 minutes.

[0597] The H2-RTP analysis curve of the Co(5%)Cu(10%) / ZrO2 catalyst over the temperature range of 100–500°C is shown in Figure 10. It shows that the low-temperature reduction peak has two maxima at 155°C and 174°C, which may correspond to the consecutive reduction of CuO to Cu2O and Cu2O to Cu, respectively. In addition, the high-temperature reduction peaks, centered at 221°C, could be related to the reduction of Co3O4 to CoO and further reduction to Co.

Claims

Claims 1. Use of a bimetallic supported catalyst comprising copper and cobalt on a zirconium dioxide support, of formula CoCu / ZrC>2, in the implementation of a process for preparing ethylene glycol from an oxalate compound by a hydrogenation reaction of said oxalate compound with hydrogen (H2) to obtain ethylene glycol.

2. Use according to claim 1, wherein said catalyst has a surface area, analyzed by BET, of 1 to 250 m 2 / g, especially from 1 to 50 m 2 / g, preferably 1 to 10 m 2 / g, especially around 5 m 2 / g, optionally in which said catalyst comprises a crystalline phase, analyzed by X-ray diffraction, crystallized in a monoclinic crystalline system, in particular said crystalline phase represents from 50 to 90% by total weight of the catalyst, preferably said crystalline phase is baddeleyite and the size of the crystals is preferably from 15 to 100 nm.

3. Use according to one of claims 1 to 2, in which the hydrogenation reaction of said oxalate compound by hydrogen to obtain ethylene glycol is selective, with a selectivity of more than 70%, preferably more than 90%, preferably greater than or equal to 95% and / or in which the hydrogenation reaction of said oxalate compound by hydrogen to obtain ethylene glycol has a yield of more than 70%, preferably more than 80%.

4. Process for the preparation of ethylene glycol comprising: o a step of hydrogenation by hydrogen of an oxalate compound, into ethylene glycol, in the presence of a bimetallic supported catalyst comprising copper and cobalt on a zirconium dioxide support, of formula CoCu / ZrC>2.

5. Process for the preparation of ethylene glycol according to claim 4, in which: • the hydrogenation step comprises o bringing into contact: said oxalate compound, dihydrogen, said supported catalyst of formula CoCu / ZrC>2, comprising cobalt and copper on a zirconium dioxide support, optionally a solvent, to obtain a reaction medium optionally pressurized, or optionally heating of said reaction medium, to obtain ethylene glycol.

6. Process for the preparation of ethylene glycol according to one of claims 4 to 5, in which said oxalate compound is of the following Formula 1: Formula 1 in which R a represents: • a linear or branched C1 to C20 alkyl group, • a C3 to C10 cycloalkyl group, • an aryl or heteroaryl group in C3 to C20 • a C5 to C20 alkyl-aryl or alkyl-heteroaryl group. in particular in which said oxalate compound is chosen from dimethyloxalate, diethyloxalate, diphenyloxalate, dibenzyloxalate, isopropyloxalate and diterbutyloxalate.

7. Process for the preparation of ethylene glycol according to one of claims 4 to 6, in which said catalyst comprises a total content of bimetallic elements copper and cobalt of 0.5 to 25% by total weight of the catalyst and in which the weight ratio between cobalt and copper varies from 1:1 to 1:5, in particular the mass composition of cobalt and copper of the catalyst is chosen from: - Co(2%)Cu(10%), - Co(5%)Cu(10%), - Co(5%)Cu(5%), - and Co(10%)Cu(10%), preferably Co(2%)Cu(10%) and Co(5%)Cu(10%), more preferably Co(5%)Cu(10%).

8. Process for the preparation of ethylene glycol according to one of claims 4 to 7, in which said zirconium dioxide support of said CoCu / ZrC>2 catalyst comprises baddeleyite in an amount of 50 to 90% by total weight of the catalyst.

9. Process for the preparation of ethylene glycol according to one of claims 4 to 8, wherein the dihydrogen is used under a pressure of 2 to 10 MPa, in particular 6 MPa, wherein the reaction medium is heated to a temperature of 100 to 250°C, in particular 180 to 220°C, optionally wherein the reaction medium is heated for 5 to 24 hours, in particular 8 or 16 hours, wherein during said step of heating the reaction medium, said bimetallic supported catalyst is activated, said activated catalyst consisting of: 80 to 100%, in particular 95 to 100%, preferably 100%, of the metallic copper atoms at a zero oxidation state Cu(0) and 80 to 100% of the cobalt atoms at an oxidation state greater than zero.

10. A bimetallic supported catalyst comprising copper and cobalt on a zirconium dioxide support, of formula CoCu / ZrC>2, wherein said catalyst has a surface area, analyzed by BET, of 1 to 75 m 2 / g, preferably 1 to 50 m 2 / g.

11. The catalyst of claim 10, wherein said catalyst has a surface area, analyzed by BET, of 1 to 10 m 2 / g, especially around 5 m 2 / g.

12. Catalyst according to one of claims 10 to 11, in which said zirconium dioxide support comprises a crystalline phase, analyzed by X-ray diffraction, crystallized in a monoclinic crystalline system.

13. Catalyst according to claim 12, wherein said crystalline phase represents from 50 to 90% by total weight of the catalyst.

14. Catalyst according to one of claims 12 to 13, in which said crystalline phase is baddeleyite.

15. Catalyst according to one of claims 10 to 14, in which said catalyst comprises a crystalline phase, analyzed by X-ray diffraction, comprising a crystallite size of 15 to 100 nm.

16. Catalyst according to one of claims 10 to 15, in which said catalyst comprises a total content of bimetallic elements copper and cobalt of 0.5 to 25% by total weight of the catalyst.

17. Catalyst according to one of claims 10 to 16, in which the weight ratio between cobalt and copper varies from 1:1 to 1:

5.

18. Catalyst according to one of claims 10 to 17, in which the mass composition of cobalt and copper of the catalyst is chosen from: - Co(2%)Cu(10%), - Co(5%)Cu(10%), - Co(5%)Cu(5%), - and Co(10%)Cu(10%), preferably Co(2%)Cu(10%) and Co(5%)Cu(10%), more preferably Co(5%)Cu(10%).

19. Catalyst according to one of claims 10 to 18, wherein said catalyst has an amount of more than 50 mol% of element copper at oxidation state (II) and / or element cobalt at oxidation state (II).

20. Catalyst according to one of claims 10 to 19, in which said catalyst is in the form of a population of micrometric particles of 1 to 500 pm, preferably in the form of a population of particles of rounded morphology.

21. Catalyst according to one of claims 10 to 20, wherein said catalyst analyzed by programmed temperature reduction (PTR) carried out in a dihydrogen reducing atmosphere over a temperature range of 30 to 900°C, is characterized by a reduction temperature of metallic copper of oxidation state (0) in the range of 150 to 250°C, in particular at a temperature higher than at least 10°C of said reduction temperature of metallic copper analyzed by PTR, the copper atoms are 80 to 100%, preferably 100% in metallic form, the cobalt atoms are 80 to 100%, preferably 100% in oxidized form.

22. Catalyst according to claim one of claims 10 to 21, wherein said catalyst under reduced atmosphere comprising dihydrogen at a pressure of 2 to 10 MPa and at a temperature of 150 to 250°C, in particular 180 to 220°C, comprises: - from 80 to 100%, in particular 95 to 100%, preferably 100%, of the metallic copper atoms Cu(0) and - from 80 to 100% of cobalt atoms in an oxidation state greater than zero.

23. Process for preparing a CoCu / ZrC>2 catalyst according to one of claims 10 to 22 comprising: • a step A of impregnation of a cobalt salt and a copper salt, dissolved in an aqueous solution, without additive and without the presence of surfactant, in a volume of water of 5 to 10 mL, on a zirconium dioxide support in powder form, with a mass ratio of the solution / mass of support of from 0.6 to 1.0; to obtain the CoCu / ZrC>2 catalyst in the form of a homogeneous mixture, said support having a surface area of ​​1 to 75 m 2 / g, preferably 1 to 50 m 2 / g, preferably from 1 to 10 m 2 / g, especially around 5 m 2 / g, and comprising a crystalline phase, analyzed by X-ray diffraction, crystallized in a monoclinic crystalline system, • a step B of drying said homogeneous mixture, preferably at a temperature of 60 to 100°C, for a period of 10 to 24 hours, to obtain the CoCu / ZrC>2 catalyst in the form of a dry homogeneous mixture, • an activation step C, comprising calcination of said dry homogeneous mixture, preferably at a temperature of 200 to 1000°C, for a period of 1 to 15 hours, to obtain said catalyst.

24. Bimetallic supported catalyst comprising copper and cobalt on a zirconium dioxide support, of formula CoCu / ZrC>2, obtainable by the process according to claim 23.

25. Catalyst according to claim 24, wherein said catalyst analyzed by programmed temperature reduction (PTR) carried out at a dihydrogen reducing atmosphere over a temperature range of 30 to 900°C, is characterized by a reduction temperature of metallic copper of oxidation state (0) in the range of 150 to 250°C, in particular at a temperature higher than at least 10°C of said reduction temperature of metallic copper analyzed by PTR, the copper atoms are 80 to 100%, preferably 100% in metallic form, the cobalt atoms are 80 to 100%, preferably 100% in oxidized form.

26. Catalyst according to claim one of claims 24 or 25, wherein said catalyst under reduced atmosphere comprising dihydrogen at a pressure of 2 to 10 MPa and at a temperature of 150 to 250°C, in particular 180 to 220°C, comprises: - from 80 to 100%, in particular 95 to 100%, preferably 100%, of the metallic copper atoms Cu(0) and - from 80 to 100% of cobalt atoms in an oxidation state greater than zero.

27. Activated bimetallic supported catalyst, comprising on the surface copper and cobalt, on a zirconium dioxide support, of formula CuCo / ZrC>2, in which the copper atoms are 80 to 100%, in particular 95 to 100%, preferably 100%, at a zero oxidation state Cu(0) and the cobalt atoms are 80 to 100%, in particular 95 to 100%, preferably 100%, at an oxidation state greater than zero.

28. Method according to one of claims 4 to 9, in which said catalyst is according to one of claims 10 to 22 and 24 to 27.

29. Use of a CoCu / ZrC>2 catalyst according to one of claims 10 to 22 and 24 to 27 for the hydrogenolysis of ethylene glycol.

30. Use of a CoCu / ZrC>2 catalyst according to one of claims 10 to 22 and 24 to 27 for depolymerizing biomass by hydrogenolysis of the ethylene glycol groups present in the compounds constituting said biomass.

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