Plasma-catalyzed direct water-gas shift reaction

Abstract

The present invention relates to a method for chemically converting a gas mixture containing carbon monoxide (CO) and water vapor (H2O) in the presence of a catalytic system, also called a catalyst, activated by a low-temperature plasma (e.g., generated by a DBD dielectric barrier discharge), according to the WGS reaction: CO + H2O → CO2 + H2. It also relates to the catalyst and the use of the catalytic system activated by a low-temperature plasma to produce high-value molecules such as hydrogen (H2).

Description

[Technical Field]

[0001] The present invention relates to the field of chemical conversion, in particular the chemical conversion of carbon monoxide (CO) and water vapor (HO), using the WGS reaction: CO + HO → CO + H in the presence of a catalyst activated by a low-temperature plasma, for example generated by a "dielectric barrier discharge", also known as DBD. The invention particularly relates to said conversion method, said catalytic system, and the use of such catalyst to produce high-value molecules such as hydrogen (H). [Background technology]

[0002] Hydrogen is a clean alternative to traditional fossil fuel-based energy sources and is considered an ideal energy choice for sustainable future development.

[0003] The water-gas shift (WGS) reaction is the method of choice for increasing the hydrogen (H2) content of syngas. This process is typically deployed after steam reforming or partial oxidation of natural gas or coal to produce hydrogen-rich syngas [1].

[0004] The WGS reaction (see Equation 1) is reversible and slightly exothermic. It is sensitive to temperature changes. At temperatures that are too high, the reaction rate increases significantly, but the endothermic "reverse water-gas shift" or "RWGS" reaction (see Equation 2) is promoted, limiting the conversion rate. Therefore, a compromise must be found between reaction rate (high temperature) and conversion rate (low temperature) [1], [2].

[0005]

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[0006]

number

[0007] Due to thermodynamic constraints, the WGS reaction is typically carried out in two separate reactors: a high-temperature shift reactor (HTS) and a low-temperature shift reactor (LTS).[1][2] According to this approach, the high temperature favors kinetics in the first reactor, while the low-temperature shift reactor favors thermodynamics, resulting in a high H2 yield.

[0008] Typically, WGS reactions are performed over an iron oxide-based catalyst in the high-temperature regime (HTS) (>300 °C) followed by a copper-based catalyst in the low-temperature regime (LTS) (200–250 °C) to optimize the process kinetically and thermodynamically. The combination of HTS and LTS processes requires careful process design, including the use of heat exchangers for thermal regulation of the reaction streams, which incurs high capital and operational costs [1], [2], [3].

[0009] Additionally, under WGS reaction conditions, catalyst deactivation due to metal sintering and carbonization is also a problem, reducing the efficiency of the process and increasing operating costs.

[0010] Activation of reagents via non-thermal plasma (NTP) assisted by catalytic WGS reactions is one of the possibilities to solve the problems of the prior art. The few studies carried out so far have been unsatisfactory in terms of stability, efficiency and cost, limiting the use of the system for industrial applications [4], [5], [6], [7]. Summary of the Invention [Problem to be solved by the invention]

[0011] The object of the present invention is to provide a method for chemically converting carbon monoxide (CO) and water vapor (HO) according to the following WGS reaction: CO + HO → CO + H, in the presence of a low-temperature plasma and a catalyst with high catalytic and energy yields, said process being capable of being exploited on a large scale. In particular, said catalyst comprises: at least one carrier containing ceria or cerium oxide, at least one first accelerator comprising copper, and at least one second promoter selected from the group consisting of transition metals, post-transition metals, lanthanides, and mixtures thereof;

[0012] Patent applications and patents [9-12] do not describe plasma catalytic conversion processes in which the catalyst is activated by low-temperature plasma. [Means for solving the problem]

[0013] A first object of the present invention is a method for chemically converting a gas mixture comprising carbon monoxide (CO) and water vapor (HO) according to the following WGS reaction: CO + HO → CO + H in the presence of a catalyst, also called catalytic system, comprising at least one carrier comprising ceria or cerium oxide activated by a low-temperature plasma, at least one first promoter comprising copper, and at least one second promoter selected from the group consisting of transition metals, post-transition metals, lanthanides, and mixtures thereof. According to one embodiment, the low-temperature plasma is a plasma generated by a dielectric barrier discharge (DBD).

[0014] A second object of the present invention is a catalyst, also referred to as a catalytic system, for converting a gas mixture containing CO and water vapor to H2, preferably in a single step. This catalyst can be activated, for example, by low-temperature plasma generated by, for example, a dielectric barrier discharge (DBD) before contacting it with the gas mixture to be converted. The catalyst of the present invention comprises at least one ceria carrier and at least two promoters, one of which contains copper. The use of such a catalyst in combination with low-temperature plasma for the conversion of gases in a WGS reaction overcomes all the drawbacks of the prior art thermal method (combining the HTS process with the LTS process) and enables the synthesis of hydrogen directly from CO and water vapor under atmospheric conditions with a higher yield than the work described in the prior art. In addition, the catalyst is resistant to pollutants, unlike thermal methods, which are particularly vulnerable to pollutants. Furthermore, it occupies 10 to 50 times less space than the catalytic systems used in conventional methods, using smaller amounts of catalyst. In addition, it uses less expensive materials than thermal methods, which often use noble, rare, or precious metal materials such as gold or platinum (Pt).

[0015] More specifically, the catalyst comprises: a carrier comprising ceria or cerium oxide, at least one first accelerator comprising copper, and at least one second promoter selected from the group consisting of transition metals, post-transition metals, lanthanides, and mixtures thereof;

[0016] A third object of the present invention relates to the use of a low-temperature plasma activated catalyst for converting a gas mixture comprising carbon monoxide (CO) and water vapor (HO) according to the WGS reaction, said catalyst comprising at least one carrier comprising ceria or cerium oxide, at least one first promoter comprising copper, and at least one second promoter selected from the group consisting of transition metals, post-transition metals, lanthanides, and mixtures thereof, activated by low-temperature plasma.

[0017] The present invention overcomes all the drawbacks of conventional thermal catalytic methods, as described in the prior art, and therefore allows for high catalytic and energy yields, making it possible to utilize it on a large scale. Prior art WGS conversion methods have high inertia (for example, 24 hours in large-scale facilities) because they require reactors to be heated to high temperatures, for example, in the range of 350°C to 500°C, and pressures of up to 80 bar. In contrast, the present method not only allows the conversion reaction to be initiated quickly, but also has high flexibility and robustness due to its implementation speed, which allows for variations in the ratio of inlet gases while maintaining a much higher average conversion yield than prior art methods.

[0018] Other features, objects and advantages of the present invention will become apparent from the following description, which is purely illustrative and not exhaustive and which should be read in conjunction with the accompanying drawings, in which: [Brief explanation of the drawings]

[0019] [Figure 1] PFD diagram of the WGS reaction. DBD-type plasma catalysis reactor for the chemical conversion of a gas mixture containing carbon monoxide (CO) and water vapor (H2O) via the following WGS reaction: CO + H2O → CO2 + H2. Figure 1 shows the experimental setup (PFD diagram) used in the example of the water-gas shift (WGS) reaction by a DBD plasma process coupled to a catalyst (also called equivalent catalyst) according to one embodiment of the present invention.

[0020] Tables 1-2 show the catalytic activity of several catalysts tested in the presence or absence of DBD plasma. The tables show the catalytic activity results obtained, particularly in terms of conversion and selectivity.

[0021] definition

[0022] The expression "between... and..." (eg, a range of values) is to be understood to include the limits (eg, the limits of this value range).

[0023] Any description of an embodiment is applicable and interchangeable with all other embodiments of the present invention.

[0024] The term "and / or" shall be understood to mean "and" and "or", for example, the term "A and / or B" shall be understood to encompass three alternatives and to mean either A and B, or A only, or B only.

[0025] The phrase "N, M and / or P" shall be understood to mean "N and / or M and / or P."

[0026] The expression "N, M and P" shall be understood to mean "N and M and P".

[0027] When an element or component is included in and / or selected from a list of elements or components, it is to be understood that such individual elements or components may be selected and combined with other individual elements or components, or may be selected to constitute a subset of two or more explicitly listed elements or components, and any element or component recited in a list of elements or components may be omitted from this list.

[0028] The term "DBD - Dielectric Barrier Discharge" means in the present invention a discharge generated between two conductive elements separated by one or more dielectric elements.

[0029] The term "dielectric" in the present invention refers to an electrically insulating material that makes it possible to ensure electrical insulation between the high voltage network associated with the electrodes and the electrically and thermally conductive tubes that are grounded through the reactor. This type of electrically insulating material is also used inside DBD cells to facilitate the accumulation of charges on the surface of this material to generate a plasma by dielectric barrier discharge (DBD).

[0030] The term "catalyst" or "catalytic system" means, in the present invention, a material that promotes a chemical reaction of a reactive species, for example a reagent fluid.

[0031] The term "plasma catalysis" means in the present invention the combination of a plasma discharge with a catalyst, for example the conversion method implements a plasma discharge coupled to a catalyst.

[0032] The terms "cold plasma" or "nonthermal plasma (NTP)" refer to a plasma in which the distribution of particles (electrons and ions) does not follow the Maxwell-Boltzmann thermal distribution. This means that the electron temperature is significantly higher than the ion temperature, and therefore the ion kinetic energy is much lower than that of the electrons. This type of plasma is often characterized by the presence of a population of high-energy electrons while the ions remain at a lower energy, hence the term "nonthermal plasma"

[13] . Dielectric barrier discharge (DBD) is an example of a cold or nonthermal plasma in which the gas temperature is kept near room temperature and the average electron energy is 2-5 eV due to the strong electric field in the plasma

[14] . The gas temperature remains close to ambient temperature. This can be controlled using a heat exchanger system (circulation of a heat transfer fluid) capable of maintaining a constant temperature, thereby ensuring control of the system in the event of exothermic or endothermic reactions. In the context of the present invention, in the case of exothermic reactions, the gas temperature can be controlled to be below 300 °C, e.g., below 280 °C or below 270 °C. If desired, the temperature of the gas can be measured by a probe (thermocouple) and the temperature of the electrons can be measured by optical emission spectroscopy.

[0033] In the context of the present invention, the terms "water-gas shift", "WGS" and "WGS reaction" refer to the reaction of direct conversion of gas to water according to Equation 1.

[0034] The term "hydrogen" should be understood to mean "dihydrogen" or "H2".

[0035] The term "carrier" or "catalyst carrier" means, in the present invention, a solid material or mixture of solid materials characterized by a high specific surface area on which the promoter(s) are deposited.

[0036] The term "promoter" or "catalyst promoter" as used herein means a solid material or mixture of solid materials that is added to the surface of a carrier material, generally in small amounts, for the purpose of increasing the efficiency and performance of the catalyst.

[0037] Of course, the present invention has been described above by way of example, and it will be appreciated that those skilled in the art can make various modifications to the present invention without departing from the scope of the invention. DETAILED DESCRIPTION OF THE INVENTION

[0038] Method for converting gas mixtures containing carbon monoxide (CO) and water vapor (H2O) according to the WGS reaction

[0039] The first object of the present invention is to provide a method for converting a gas mixture containing carbon monoxide (CO) and water vapor (HO) in the presence of a low-temperature plasma and a catalyst according to the following WGS reaction: CO + HO → CO + H. The catalyst is activated by a low-temperature plasma, preferably generated by a dielectric barrier discharge (DBD), before the conversion reaction of the gas species begins. The catalyst includes at least one carrier containing ceria or cerium oxide, at least one first promoter containing copper (in metallic or oxide form), and at least one second promoter selected from the group consisting of transition metals, post-transition metals, lanthanides, and mixtures thereof (each independently in metallic or oxide form). The purpose of this method is to produce high-value molecules, such as hydrogen (H), in a single step.

[0040] The gas mixture converted according to the WGS reaction contains carbon monoxide (CO) and water vapor (HO). It may further contain other gases, such as, for example, carbon dioxide (CO), methane (CH), nitrogen (N), oxygen (O), and / or dihydrogen (H). According to one embodiment of the present invention, the gas mixture converted according to the WGS reaction mainly contains carbon monoxide (CO) and water vapor (HO), and optionally one or more gases selected from the group consisting of carbon dioxide (CO), methane (CH), nitrogen (N), oxygen (O), and dihydrogen (H), and mixtures thereof. According to this embodiment, the gas mixture converted according to the WGS reaction contains, for example, more than 50 mol%, for example, more than 60 mol%, more than 70 mol%, more than 80 mol%, more than 90 mol%, more than 95 mol%, or even more than 98 mol% of carbon monoxide (CO) and water vapor (HO) relative to the total number of moles involved in the WGS conversion reaction according to the present invention.

[0041] The method for converting a gas mixture containing carbon monoxide (CO) and water vapor (HO) according to the WGS reaction (Equation 1) is carried out in the presence of the catalyst of the present invention and low-temperature plasma, preferably plasma generated by dielectric barrier discharge (DBD). The synergistic effect of plasma catalysis in this method shows great potential for the direct synthesis of hydrogen, a high-value gas, from CO and water vapor.

[0042] The conversion method of the present invention comprises a first step of activating the catalyst by means of low-temperature plasma before feeding the gas mixture to be converted into the reactor. The catalyst according to the present invention is activated by low-temperature plasma, i.e. advantageously reduced in situ under H2 as discharge gas in a low-temperature plasma, preferably DBD plasma. The step of activating the catalyst is particularly advantageous when its components are in oxide form.

[0043] The conversion method of the present invention is carried out in a low-temperature plasma reactor, preferably a DBD plasma reactor. A catalyst is typically placed between the electrodes of the low-temperature plasma reactor and then activated by an electrical discharge, which results in the formation of a low-temperature plasma and thus negative or positive polarization of the catalytic sites. The gas mixture to be converted is then introduced into the reactor and flows between the electrodes in the reactor for conversion via the WGS reaction. The WGS conversion reaction is carried out under the low-temperature plasma.

[0044] According to one embodiment of the method of the present invention, said conversion is carried out in the presence of a low-temperature plasma at a temperature below 300°C, below 290°C, below 280°C or even below 270°C.

[0045] The conversion process can in particular be a continuous or semi-continuous process, with the introduction of the gas mixture to be converted and the extraction of the reaction products each being carried out under a continuous or semi-continuous gas flow depending on the availability of energy, which represents an advantage in the process according to the invention, taking into account the flexibility of the system and the instantaneous character of the reaction.

[0046] According to one embodiment of the present method, the selected catalyst is placed between the electrodes of a DBD reactor, allowing gas species to flow through the catalyst, and activated by a high-voltage discharge (on the order of kV) lasting from a few nanoseconds to a few microseconds. This polarization, coupled with adsorption, desorption, and catalyst / gas interactions, results in plasma formation and catalytic activation. The inventors have discovered that this catalyst activation step is essential for the performance of the present conversion process. Electrical energy supplied to the fixed bed in the form of a sinusoidal or pulsed high voltage generates multiple currents in the HV (high voltage) carrier during positive and negative polarization. These streamers, lasting from hundreds of picoseconds to a few tenths of a nanosecond, are responsible for the negative or positive polarization of the catalytic sites.

[0047] During the process of the present invention, a low-temperature plasma is generated, creating a strong electric field that maintains the catalyst in an activated state, more specifically between the catalyst particles, or near, upstream or downstream of the catalyst system in the gas stream. This strong electric field is typically 10 3 ~10 10The electric field generated by the low-temperature plasma is typically a negative or positive polarization of catalytic sites. The latter are typically inserted directly into the reactor to form a catalytic bed through which the gas passes (typically not coated on the reactor wall in the form of a layer). The structure of the catalyst (including the availability of key catalytic components) and the selection of these components are crucial for achieving high conversion yields, depending on the gas molecules being converted. The polarization of catalytic sites triggers adsorption and desorption reactions, which are essential for carrying out the method of the present invention. The polarization process, as well as the activation and limiting steps of the catalytic sites required for the chemical reaction, are possible in the presence of low-temperature plasma at low gas temperatures (e.g., below 300°C, or below 290°C, 280°C, or below 270°C). Conventional processes without polarization require higher operating temperatures, typically in the range of 350°C to 500°C, and require two steps: LTS and HTS.

[0048] The reactor comprises at least one inlet allowing the supply of the gases to be converted, which contain CO and water vapor, and an outlet for discharging the products formed, in particular H2.

[0049] According to one embodiment, the method of the present invention comprises the following steps in order: a) activating a catalyst placed between the electrodes of a low-temperature plasma reactor, preferably a DBD plasma reactor, by generating a low-temperature plasma under H2 as a discharge gas; b) introducing the gas mixture to be converted between electrodes in a reactor through a catalyst; c) Transforming the gas mixture in a low-temperature plasma according to the WGS reaction, for example continuously or semi-continuously, by circulating the gas flow between electrodes in the reactor.

[0050] The method of the present invention may further comprise extracting the products of the reaction and / or recycling them in the method of the present invention. In an industrial process, the produced hydrogen (H2) is separated from the unconverted gas mixture (CO, HO) and carbon dioxide (CO2). The mixture of unconverted reagents, carbon monoxide (CO) and water vapor (HO) is reintroduced into the reactor. This results in a 100% conversion rate for the entire process and minimizes reagent loss.

[0051] According to one embodiment of the method of the present invention, there is an excess of water vapor (HO) relative to carbon monoxide (CO). According to one embodiment of the method of the present invention, the molar ratio of water vapor (HO) / carbon monoxide (CO) in the gas mixture to be converted varies between 1 and 5 (HO / CO ratio = 5 means that there are 5 times more water molecules than CO molecules), for example between 1 and 4, preferably between 1 and 3, between 1 and 2.5, between 1 and 2, or between 1 and 1.5. By way of example, the HO / CO ratio can be set to 1.1±0.1, which means that it is likely to vary between 1 and 1.2 (with excess water vapor).

[0052] As shown in Figure 1, water 1 stored in a tank is first propelled by inert gas (Ar) 3 and then flows through a mass flow controller 4. It is then vaporized and mixed with a CO (carrier gas) stream 2, also controlled by a mass flow meter 4, using a controlled evaporation and mixing (CEM) system 6. The gaseous mixture is then transported along a heated tube 7 equipped with a pressure gauge 5 into a DBD plasma catalytic reactor 9. The reactor contains a catalyst bed 10 and is connected to a plasma generator 8. The product stream 11 then goes to a water condensation system 12 and then to a condensate collection tank 13. The gas flow rate is measured using a volumetric flow meter 14. The composition of the gas is analyzed using a micro-GC 15, into which argon 3 (carrier gas for the micro-GC) is introduced and then directed through a vent 16.

[0053] According to one embodiment of the present invention, the catalyst of the present invention is activated by plasma DBD by supplying a power of less than 25 W / g of catalyst (i.e., the catalyst present in the reactor, specifically in the catalyst bed).

[0054] The conversion reaction is advantageously carried out at atmospheric pressure (10 5 Pressures close to or equal to 1.10 Pa, e.g. 4 Pa~3.10 5 The conversion reaction may be carried out under pseudoadiabatic conditions, i.e., without insulation and external heating, or under isothermal conditions, i.e., with insulation and / or external temperature control.

[0055] According to one embodiment of the method of the present invention, the DBD plasma is generated by applying a voltage between two electrodes of between 1 and 25 kV, preferably between 5 and 15 kV, and / or having a frequency between 1 kHz and 100 kHz. The gas hourly space velocity (GHSV) is preferably between 1000 h -1 From 150,000h -1 Between 100,000 hours, preferably -1 It may be less than.

[0056] A cooling system may be present between the vessel intended to receive the product produced by the conversion reaction and the outlet of the reactor, so as to condense and remove water vapor that has not reacted during the conversion reaction.

[0057] Catalyst according to the present invention

[0058] A second object of the present invention relates to a catalyst for converting a gas mixture comprising carbon monoxide (CO) and water vapor (H2O) according to the following WGS reaction: CO + H2O → CO2 + H2, said conversion being carried out in the presence of a low-temperature plasma.

[0059] More specifically, the catalyst comprises: a carrier comprising ceria or cerium oxide, at least one first accelerator comprising copper, and at least one second promoter selected from the group consisting of transition metals, post-transition metals, lanthanides, and mixtures thereof;

[0060] In the context of the present invention, the terms "catalytic system" and "catalyst" are equivalent and interchangeable.

[0061] According to one embodiment of the present invention, the catalyst is referred to as a bimetallic / trimetallic catalyst. It should be noted that the concepts of bimetallic and trimetallic catalysts relate specifically to the species present in the catalyst, regardless of the carrier used. For example, if a catalyst is doped with two promoters, it is referred to as a bimetallic catalyst, and if a catalyst is doped with three promoters, it is referred to as a trimetallic catalyst.

[0062] The carriers used in the context of the present invention are selected for their ability to adsorb reagents, more specifically CO, their thermal stability, and their high specific surface area, which facilitates the plasma-catalyst interface and allows for various reaction pathways in the surface chemistry. They are also selected for their dielectric properties, which can affect the plasma characteristics and modify the discharge behavior of the plasma, especially DBD plasmas in use, the electric field and electron density due to the dielectric permittivity, and polarization effects that give rise to local electric fields.

[0063] According to one embodiment of the present invention, the catalyst carrier comprises ceria, and in particular the carrier may consist of ceria. According to one embodiment or use, the carrier is cerium oxide. Thus, the catalyst carrier may further comprise other components, such as mixed oxides and / or aluminum and / or zirconium.

[0064] According to one embodiment of the present invention, the catalyst carrier is comprised of ceria and optionally alumina, each independently in the form of ceria / alumina or their corresponding oxide forms.

[0065] According to this embodiment, the catalyst carrier may consist exclusively of ceria and / or cerium oxide. Alternatively, the catalyst carrier may consist exclusively of ceria and / or cerium oxide and alumina and / or aluminum oxide. When the catalyst carrier consists of a mixture of ceria and alumina (including in oxide form), these species may be present in a Ce / Al mass ratio varying between 10:90 and 90:10, for example, 20:80 to 80:20, 40:60 to 75:25, or 50:50 to 70:30.

[0066] According to a preferred embodiment of the present invention, the catalyst carrier is made of ceria and / or cerium oxide. According to this preferred embodiment, the catalyst carrier is free of other components or contains other components in amounts that do not significantly affect its properties. Thus, according to this embodiment, the catalyst carrier contains less than 5 wt. % of other components, less than 4 wt. % of other components, less than 3 wt. % of other components, less than 2 wt. % of other components, less than 1 wt. % of other components, or even less than 0.1 wt. % of other components.

[0067] The choice of carrier is important as it affects the physicochemical properties (basicity, acidity, reducibility, oxygen mobility due to intrinsic defects present on the surface, etc.), as well as the textural properties (pore volume, pore size, specific surface area, etc.) and electrical properties (dielectric constant, conductivity, etc.), thus modulating the catalytic performance of the system.

[0068] The preparation of the catalyst carrier is described in detail below: The carrier used in the context of the present invention may also be a commercially available carrier.

[0069] The catalyst according to the present invention improves the catalytic performance of the WGS reaction, i.e., the CO conversion rate and the selectivity to the desired products (hydrogen and carbon monoxide), while making it possible to produce high-value-added molecules such as hydrogen during the conversion reaction of a gas mixture containing carbon monoxide (CO) and water vapor (HO) according to the WGS reaction in the presence of a catalyst and a low-temperature plasma, preferably a plasma generated by a dielectric barrier discharge (DBD).

[0070] To this end, the catalyst according to the invention comprises at least two promoters. The inventors have demonstrated that when the catalyst according to the invention is in the form of a carrier comprising ceria and comprises at least two promoters, and when said catalyst is also activated by low-temperature plasma before starting the conversion reaction, the performance of the reaction is significantly higher than that achieved without prior catalyst activation, or when the catalyst does not comprise a copper promoter, or when the catalyst does not comprise at least two promoters.

[0071] In the context of the present invention, the promoter is in any of its oxidation states, in particular in metallic or oxide form.

[0072] The promoter acts as a doping agent and influences the physicochemical, textural and conductive properties of the catalyst system. The promoter according to the invention advantageously has suitable surface physicochemical properties that aid in the binding of reagents, as well as suitable dielectric properties that allow improving the conductivity of the resulting catalyst, leading to high CO conversion.

[0073] Thus, in the context of the present invention, the first promoter comprises copper. In the context of the present invention, copper is in any of its oxidation states, in particular in metallic or oxidic form (CuO or CuO). The mass content of copper in the catalyst advantageously varies between 1 and 50% by weight, for example between 2 and 40% by weight, preferably less than 30% by weight, relative to the weight of the carrier. Particularly advantageously, the catalyst comprises 5 to 16% by weight of copper or 7 to 13% by weight of copper, for example about 10% by weight ± 1% by weight of copper, relative to the weight of the carrier.

[0074] According to the present invention, the catalyst comprises at least one second promoter selected from the group consisting of transition metals, post-transition metals, lanthanides, and mixtures thereof, each independently in metallic or oxide form.

[0075] Thus, in the context of the present invention, the at least one second promoter is selected from the group consisting of transition metals such as zinc and iron, post-transition metals such as aluminum and gallium, lanthanides such as lanthanum, and mixtures thereof. In the context of the present invention, the at least one second promoter is in any of its oxidation states, in particular in metallic or oxide form.

[0076] In the context of the present invention, the transition metal may in particular be selected from the group consisting of cobalt, silver, iron, copper, molybdenum, vanadium, manganese, chromium, yttrium, titanium, tantalum, zinc and zirconium. When the promoter is a transition metal, it is preferably iron or zinc, even more preferably zinc.

[0077] In the context of the present invention, the post-transition metal may be selected from the group consisting of gallium, indium, tin, thallium, lead, bismuth and aluminum. When the promoter is a post-transition metal, it is preferably gallium or aluminum, even more preferably aluminum.

[0078] In the context of the present invention, the lanthanide may be selected from the group consisting of lanthanum, cerium, praseodymium, neodymium, promethium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium and lutetium. When the promoter is a lanthanide, it is preferably cerium or lanthanum, even more preferably lanthanum.

[0079] According to one embodiment of the present invention, the at least one second catalyst promoter is selected from the group consisting of zinc, iron, lanthanum, gallium, aluminum, and mixtures thereof, each independently in metallic or oxide form. More preferably, the at least one second promoter is selected from the group consisting of zinc, aluminum, and mixtures thereof, each independently in metallic or oxide form.

[0080] According to one embodiment, the catalyst preferably comprises two or three promoters. According to this embodiment, the catalyst is bimetallic or trimetallic. Preferably, the bimetallic or trimetallic catalyst consists essentially of a carrier comprising ceria and / or cerium oxide and two or three promoters, of which the first promoter comprises copper (in metallic or oxide form), and the second promoter and optionally the third promoter(s) comprise zinc, iron, lanthanum, gallium, aluminum, or mixtures thereof (each of these metals independently in metallic or oxide form).

[0081] According to one embodiment, the catalyst does not contain precious, rare, or precious metal materials, such as gold (Au) or platinum (Pt), or contains these materials in amounts that do not significantly affect its properties. Thus, according to this embodiment, the catalyst contains less than 3 wt. % precious, rare, or precious metal materials, less than 2 wt. %, less than 1 wt. %, less than 0.5 wt. %, less than 0.1 wt. %, or even less than 0.01 wt. % precious, rare, or precious metal materials. Indeed, in the context of the present invention, less expensive materials are used compared to thermal processes that often use precious, rare, or precious metal materials, such as gold or platinum.

[0082] According to one embodiment of the present invention, the mass content of the accelerator varies between 0.1% and 40% by weight relative to the weight of the carrier, for example between 0.2% and 30% by weight, in particular between 0.3% and 20% by weight, preferably between 0.5% and 15% by weight, in particular between 1% and 12% by weight, even more preferably between 2% and 11% by weight relative to the weight of the carrier.

[0083] According to the invention, the catalyst according to the invention comprises at least two promoters, i.e. two or more promoters, for example three promoters. According to one embodiment, the catalyst is trimetallic and doped with three promoters, of which the first promoter is copper (in metallic or oxidic form), the mass content of which in the catalyst may preferably vary between 8 and 15% by weight ±0.2% by weight relative to the weight of the carrier; the second promoter may in particular be zinc (in metallic or oxidic form), the mass content of which in the catalyst may preferably vary between 3 and 8% by weight ±0.5% by weight relative to the weight of the carrier; and the third promoter may in particular be aluminum (in metallic or oxidic form), the mass content of which in the catalyst may preferably vary between 1 and 5% by weight ±0.5% by weight relative to the weight of the carrier.

[0084] According to a particular embodiment, the trimetallic catalyst consists of three promoters, of which the first promoter is copper (in metallic or oxidic form), the mass content of which in the catalyst is preferably about 10% by weight ±0.2% by weight relative to the weight of the carrier, the second promoter is zinc (in metallic or oxidic form), the mass content of which in the catalyst is preferably about 5% by weight ±0.5% by weight relative to the weight of the carrier, and the third promoter is aluminum (in metallic or oxidic form), the mass content of which in the catalyst is preferably about 3% by weight ±0.5% by weight relative to the weight of the carrier.

[0085] The catalyst inserted into the reactor forms a catalyst bed and can be in different forms (beads, monoliths, powder, etc.). In the case of a powder, the particles forming the powder can have an average size of, for example, 1 μm to 1 mm, for example 100 μm to 1 mm, in particular 200 μm to 800 μm, preferably about 600 μm ± 20 μm. In particular, the particle size can be adapted depending on the production scale used. The catalyst can also be in the form of beads (in particular by compressing the powder in a mold) with an average size of less than 5 cm.

[0086] According to one embodiment of the present invention, the carrier comprising ceria or cerium oxide and the at least two promoters form a homogeneous mixture, meaning that the promoters are uniformly distributed throughout the entire volume of the catalyst.

[0087] Catalyst Preparation Method

[0088] The catalyst according to the invention may be prepared according to different methods.

[0089] The catalyst can be prepared by a method comprising contacting a carrier containing ceria or cerium oxide with a precursor of a first copper promoter and at least one precursor of a second promoter. This step allows the formation of a solid containing the carrier, copper, and the second promoter(s). The method optionally comprises a step of calcining the mixture thus obtained. The contacting step may be preceded by a step of modifying the carrier. Furthermore, after the optional calcination step, a step of reducing the calcined mixture is optionally performed. The reduction step may be carried out in situ in a non-thermal plasma device under hydrogen.

[0090] The step of contacting the carrier with the copper precursor and the precursor of the second promoter can be carried out by several preparation methods, for example, by impregnation, co-precipitation, or other methods such as sol-gel reaction or hydrothermal methods, whereby the carrier is contacted with the copper precursor and the precursor of at least one second promoter. The first two specific embodiments (also called sub-variants) are described in more detail below.

[0091] The copper precursor and the precursor of the second promoter may be any compound or mixture of compounds containing the metal used as the active metal / promoter, more particularly, a salt of the metal, an oxide of the metal, or a mixture thereof, preferably a salt of the metal or a mixture of salts of the metal. The salt of the metal (meaning a non-hydrated salt or a hydrated salt, or even a polyhydrated salt) may be selected, for example, from chlorides, nitrates, sulfates, carbonates, acetates, acetylacetonates, tartrates, and citrates of the metal, and mixtures thereof, preferably nitrates of the metal. When the promoter is a mixture of several metals, the precursor may be a mixture of different salts and / or oxides of the metals.

[0092] Thus, according to a first alternative embodiment of the method according to the invention, the method for preparing a catalyst according to the invention comprises: - contacting a carrier comprising ceria or cerium oxide with a copper precursor and one or more precursors of promoter(s); - optionally, calcining the mixture obtained after contacting the components with each other; Optionally, reducing the calcined mixture obtained in the previous step.

[0093] According to a second alternative embodiment of the method according to the invention, the method for preparing the catalyst according to the invention comprises: - contacting a carrier comprising ceria or cerium oxide with a copper precursor and one or more precursors of promoter(s); - calcining the mixture obtained after contacting the components with each other; Optionally, reducing the calcined mixture obtained in the previous step.

[0094] According to a third alternative embodiment of the method according to the invention, the method for preparing a catalyst according to the invention comprises: - contacting a carrier comprising ceria or cerium oxide with a copper precursor and one or more precursors of promoter(s); - calcining the mixture obtained after contacting the components with each other; - reducing the calcined mixture obtained in the previous step.

[0095] According to a fourth alternative embodiment of the process according to the invention, the process for preparing a catalyst according to the invention comprises: - modifying a carrier comprising alumina; - contacting the modified carrier with one or more precursors of a copper precursor and promoter(s); - optionally, calcining the mixture obtained after contacting the components with each other; Optionally, reducing the calcined mixture obtained in the previous step.

[0096] The step of bringing the components into contact with one another may in particular be carried out by impregnation. More particularly, according to an embodiment of this first subvariant, the method comprises the following steps: 1) preparing a carrier; 2) Bringing the components into contact with each other by impregnation.

[0097] Step 1) of preparing the carrier itself comprises the following substeps: 1.1) A suspension containing a ceria precursor or a suspension containing a cerium oxide precursor is prepared. According to this step 1.1), the carrier precursor corresponds to a ceria precursor or a mixture of several precursors. When the carrier is a mixture, in particular a mixed oxide of cerium and alumina, a suspension of the cerium precursor and a suspension of the alumina precursor are advantageously prepared separately and then mixed in a ratio that allows the desired Ce / Al molar ratio to be obtained in the mixture, in particular in the final mixed oxide of cerium and alumina. 1.2) Mix the suspension obtained from step 1.1). In particular, these precursors are added at room temperature, for example 20-25° C., with continuous mixing for 30 minutes to several hours, for example 30 minutes to 3 hours. 1.3) The solid obtained in step 1.2) is recovered by removing excess water, in particular by evaporating or filtering the water, and then drying the solid obtained. The drying step may in particular be carried out at a temperature below 150°C, typically at a temperature of about 100°C, for a duration varying for example between 5 and 48 hours. 1.4) Calcining the solid resulting from step 1.3) to obtain the carrier. The product resulting from step 1.3) is calcined, for example at a temperature between 300°C and 600°C. This calcination step can be carried out for a duration varying from 3 hours or more, for example between 3 and 6 hours. This step results in the thermal decomposition of the nitrates to produce the oxides.

[0098] Step 2) of contacting the components with each other comprises the following substeps: 2.1) An aqueous suspension is prepared containing a copper precursor and one or more precursors of a promoter. During this step, an appropriate mass of each precursor is added to an appropriate volume of solvent, such as water. "Appropriate mass" and "appropriate volume" refer to the appropriate amounts of precursor and solvent (especially water) to obtain the desired mass contents of copper and promoter in the final catalyst. 2.2) The carrier obtained from step 1) is added to the aqueous solution obtained from step 2.1) to obtain a suspension. 2.3) Mix the suspension obtained from step 2.2). The addition of these precursors is carried out at room temperature, for example 20-25°C, with continuous mixing for 30 minutes to several hours, for example 30 minutes to 3 hours. 2.4) The solid containing the carrier, copper and promoter obtained in step 2.3) is recovered by removing excess water, in particular by evaporating or filtering the water, and then drying the obtained solid. The drying step may be carried out at a temperature of, for example, below 150°C, typically at a temperature of about 100°C, for a duration in the range of, for example, 7 hours to 48 hours. 2.5) Calcining the solid resulting from step 2.4) to obtain the catalyst system. The product resulting from step 2.4) is calcined, for example at a temperature between 300°C and 600°C. This calcination step can be carried out for a duration varying from 3 hours or more, for example between 3 and 6 hours. This step results in the thermal decomposition of the nitrates to produce the oxides.

[0099] This first sub-variant embodiment is also called the wet impregnation method. It consists in impregnating the carrier with a copper precursor and a promoter precursor.

[0100] The step of contacting the components with each other may alternatively be carried out by co-precipitation. More specifically, according to a second subvariant embodiment, the method for preparing the catalyst comprises: 1') preparing a carrier; 2') contacting the carrier with the copper precursor and the promoter, such that contacting the components with each other is carried out by co-precipitation.

[0101] Step 1') of preparing the carrier consists of preparing an aqueous solution containing a copper precursor and a precursor of the promoter. This step is identical to step 2.1) of the wet impregnation method described above.

[0102] The step 2') of contacting the components with each other comprises the following sub-steps: 2.1') ​​A carrier is added to the solution obtained from step 1') to obtain a suspension. This step is identical to step 2.2) of the wet impregnation method described above. 2.2') Add base to the suspension obtained from step 2.1'). During this step, a base is added to the suspension obtained from step 2.1'). This base is advantageously a hydroxide salt such as sodium hydroxide, potassium hydroxide, sodium carbonate or potassium carbonate, preferably sodium hydroxide. It can be used in the form of a solution, in particular an aqueous solution. The base is added gradually dropwise until the pH of the suspension (consisting of a solid suspended in a liquid solution) is between 8 and 12, preferably about 10. Step 2.2') may be carried out at a temperature between 60°C and 100°C, in particular between 70°C and 90°C, preferably about 80°C. 2.3') Mix the suspension obtained from step 2.2'). This step aims to precipitate copper hydroxide and hydroxides of other metals used as promoters on the surface of the carrier. Mixing, particularly by stirring, is carried out at a temperature of, for example, 60°C to 100°C, preferably about 80°C. This mixing step can be carried out for a duration of at least 2 hours, typically about 3 hours. 2.4') The solid containing the carrier, copper, and promoter obtained in step 2.3') is recovered and calcined to obtain the catalyst system. This step is identical to step 2.5) of the wet impregnation process.

[0103] This second subvariant embodiment makes it possible to precipitate copper hydroxide and the hydroxide of the metal used as promoter on the surface of the carrier.

[0104] Optionally, the step of contacting the components with each other may also be carried out by other preparation methods, such as a sol-gel reaction or a hydrothermal method, whereby the carrier is contacted with the copper precursor and the precursor of at least one second promoter.

[0105] Use of the catalyst according to the invention

[0106] The present invention also relates to the use of a catalyst and low-temperature plasma for converting a gas mixture comprising carbon monoxide (CO) and water vapor (HO) according to the following WGS reaction: CO + HO → CO + H, wherein the catalyst comprises at least one carrier comprising ceria or cerium oxide, at least one promoter comprising copper, and at least one second promoter selected from the group consisting of transition metals, post-transition metals, lanthanides, and mixtures thereof, and wherein the catalyst is further activated by low-temperature plasma before contacting with the gas mixture to be converted.

[0107] The invention particularly relates to the use of the catalyst of the invention and a low-temperature plasma, preferably generated by a dielectric barrier discharge (DBD), for converting a gas mixture comprising carbon monoxide (CO) and water vapor (HO) according to the WGS reaction.

[0108] Indeed, the inventors have found that the combination of a catalyst according to the invention with a low-temperature plasma, preferably a plasma generated by a dielectric barrier discharge (DBD), shows an increased efficiency in converting a gas mixture comprising carbon monoxide (CO) and water vapor (HO) according to the WGS reaction, in particular if the catalyst is activated by the low-temperature plasma before being brought into contact with the gas mixture to be converted.

[0109] The present invention also relates to the use of a catalyst according to the invention for producing dihydrogen (H2) from a gas mixture comprising carbon monoxide (CO) and water vapor (H2O) according to the WGS reaction.

[0110] List of cited references [1] W. Uribe-Soto, J.-F. Portha, J.-M. Commenge, and L. Falk, “A review of thermochemical processes and technologies to use steelworks off-gases,” Renew.Sustain.Energy Rev.,vol.74,no.Supplement C,pp.809-823 Jul.2017. [2] T.L.LeValley,A.R.Richard,and M.Fan,“The progress in water gas shift and steam reforming hydrogen production technologies-A review,” Int.J.Hydrog.Energy,vol.39,no.30,pp.16983-17000 Oct.2014. [3] Dejiang Zhou;Renwu Zhou;Rusen Zhou;Baowang Liu;Tianqi Zhang;Yubin Xian;Patrick J.Cullen;Xinpei Lu;Kostya(Ken)Ostrikov;(2021).Sustainable ammonia production by non-thermal plasmas:Status,mechanisms,and opportunities.Chemical Engineering Journal,https: / / doi.org / doi:10.1016 / j.cej.2021.129544 [4] Jingjing Li,Sarayute Chansai,Christopher Hardacre and Xiaolei Fan,Non thermal plasma assisted water-gas shift reactions under mild conditions:state of the art and a future perspective,Catalysis Today,(2022)https: / / doi.org / 10.1016 / j.cattod.2022.11.017 [5] Amit K Jaiswal et al 2020 J.Phys.D:Appl.Phys.53 465205,https: / / doi.org / 10.1016 / j.cattod.2022.11.017 [6] Wangkawong, K., Phanichphant, S., Inceesungvorn, B. et al. Kinetics of Water Gas Shift Reaction on Au / CeZrO4:A Comparison Between Conventional Heating and Dielectric Barrier Discharge(DBD)Plasma Activation.Top Catal 63,363-369(2020).https: / / doi.org / 10.1007 / s11244-020-01245-8 [7] Xu, S., Chansai, S., Stere, C. et al.Sustaining metal-organic frameworks for water-gas shift catalysis by non-thermal plasma.Nat Catal 2,142-148(2019).https: / / doi.org / 10.1038 / s41929-018-0206-2 [8] Miriam Gonzalez-Castano;Bogdan Dorneanu;Harvey Arellano-Garcia;(2021).The reverse water gas shift reaction: a process systems engineering perspective.Reaction Chemistry&Engineering,https: / / doi.org / 10.1039 / d0re00478b [9] U.S. Patent Application Publication No. 2007 / 059235(A1) - GM Global Technology Operations LLC

[10] U.S. Patent Application Publication No. 2008 / 131744(A1) - Tetros Innovations LLC

[11] European Patent No. 1866083(B1) - University of REGINA

[12] Patent Application WO 2013 / 110716(A1) - SGE Scandgreen Energy AB

[13] Chen, FF (1984). “Introduction to Plasma Physics and Controlled Fusion.” Springer. ISBN:978-0-306-41332-9.

[14] Fridman, A. (2008). “Plasma Chemistry.” Cambridge University Press. ISBN:978-0521886678. [Example]

[0111] The present invention will now be described in more detail with reference to the following examples, the purpose of which is merely illustrative and is not intended to limit the scope of the invention.

[0112] A. Preparation of various catalysts by wet impregnation

[0113] Various catalyst systems are prepared by wet impregnation.

[0114] Different carriers were used to prepare the catalysts in Tables 1 and 2 below: 1) Cerium oxide - Nre002(Ce), commercially available from Solvay; 2) Aluminum oxide (Al200, specific surface area = 200 m), commercially available from Saint Gobain 2 / g), 3) cerium-zirconium (CZ) mixed oxide, commercially available from Sigma Aldrich, and 4) Molar composition Ce 0.5 Al 0.5 The cerium-aluminum mixed oxide of O2 was synthesized by the inventors according to the method described above.

[0115] Catalyst systems doped with copper-based promoters and other promoter(s) are prepared from aqueous solutions containing Cu(NO3)2.3H2O (Sigma-Aldrich) and one or more promoter precursors selected from Zn(NO3)2.6H2O, Al(NO3)3.9H2O, La(NO3)2.6H2O, and Ga(NO3)2.xH2O, Fe(NO3)2.9H2O (all commercially available from Sigma-Aldrich).

[0116] The salt of the promoter precursor(s) is dissolved in 50 ml of water at room temperature with stirring. The appropriate carrier mass is added to the aqueous solution containing the metal salt mixture and maintained under stirring for 2 hours. For the catalyst "10% Cu 5% Zn 3% Al / Ce" (one of the catalysts according to the present invention), the Cu promoter content is 10 wt. % relative to the weight of the carrier, the Zn promoter content is 5 wt. % relative to the weight of the carrier, and the Al promoter content is 3 wt. % relative to the weight of the carrier. Therefore, 0.38 g of copper nitrate (accounting for a copper content of 10 wt. % relative to the weight of the carrier), 0.227 g of zinc nitrate (accounting for a zinc content of 5 wt. % relative to the weight of the carrier), 0.417 g of aluminum nitrate (accounting for an aluminum content of 3 wt. % relative to the weight of the carrier), and 1 g of Ce carrier are mixed. The mixture is then placed in a rotary evaporator at 65°C to remove excess water.

[0117] After impregnation and water evaporation, all samples were collected and dried in an oven at 100°C for 8 hours, then calcined in air at 550°C for 4 hours with a temperature ramp rate of 10°C / min. After calcination, the samples were crushed by hand and sieved to an average particle size of 50-200 μm.

[0118] B. Conversion of a gas mixture consisting of carbon monoxide (CO) and water vapor (HO) by the WGS reaction in the presence of different catalysts

[0119] An example of the procedure for hydrogen production according to the present invention is as follows: 471 mg of the catalyst "10% Cu 5% Zn 3% Al / Ce" is placed between the electrodes of a DBD reactor. A non-thermal dielectric barrier discharge (DBD) plasma is then generated between two electrodes: a cylindrical copper electrode placed inside an alumina tube (3 mm diameter) surrounded by a coaxial quartz tube (10 mm inner diameter, 1 mm thickness), and a steel wire wrapped around the outside of the quartz tube and acting as a ground electrode (grounded via a 2 nF external capacitor). In this configuration, the discharge is maintained within a 2.5 mm space and covers a length of approximately 1 cm. The catalyst is then activated in situ under non-thermal DBD plasma with H2 as the discharge gas for a duration of 60 minutes.

[0120] The reactor is then fed with a mixture of gases containing carbon monoxide and water vapor. The total gas flow rate used during the process is 100 ml / min STP (standard temperature and pressure) at atmospheric pressure and a temperature of 20 °C, and the reaction time is 17,000 h. -1 The HO / CO molar ratio is 1 / 1. The water is first driven by an inert gas (Ar) and then flows through a mass flow meter. It is then vaporized and mixed with carbon monoxide using a liquid vaporization feed system (Bronkhorst MFC). The gas mixture is then transported along a heated tube into the DBD plasma reactor.

[0121] The activity and selectivity of the different catalysts tested were measured and are reported in Tables 1 and 2.

[0122] The experiments shown in Table 2 were carried out using an isothermal reactor surrounded by a jacket heated by a 250°C oil circulation heating system. A Julabo oil circulator was used to control the reactor temperature by pumping thermal oil through the circulation system.

[0123] The following equations were used to estimate the catalyst performance and calculate the CO conversion, H2 and CO2 selectivity:

number

number

number

[0124] C. Results

[0125] Table 1 below lists the catalysts tested in these tests ("c" indicates a control catalyst and "i" indicates a catalyst according to the invention) and shows the catalytic activity results obtained in terms of CO conversion and H and CO selectivity. [Table 1] [Table 2]

[0126] As shown in the results of Tests 24c and 25c in Table 2, without the cold plasma during the conversion reaction, no change in the composition of the evolved gas is observed (very little conversion). After the plasma is switched on and stabilized, the produced hydrogen is obtained at the reactor outlet - Tables 1 and 2, Tests 1 to 23. These results demonstrate the importance of combined plasma catalysis for the WGS conversion reaction. Furthermore, preactivating the catalyst with cold plasma before contacting it with the gas mixture to be converted significantly improves the conversion efficiency (especially comparing Tests 21i and 23c).

Claims

1. The following WGS reaction: ++H ２ O→[ ２ +H ２ According to ２ 1. A method for converting a gas mixture containing O, the method comprising the steps of: a carrier comprising ceria or cerium oxide, at least one first promoter comprising copper in metallic or oxide form, and at least one second promoter selected from the group consisting of transition metals, post-transition metals, lanthanides, and mixtures thereof, each independently in metallic or oxide form; and a catalyst comprising 3. A method according to claim 1, wherein the catalyst is activated by a low-temperature plasma before contacting it with the gas mixture to be converted.

2. 10. The method of claim 1, wherein the second promoter is zinc and / or aluminum, each independently in metallic or oxide form.

3. 3. The method according to claim 1, wherein the catalyst contains at least 2% by weight, preferably at least 5% by weight, of a promoter comprising copper, relative to the total weight of the carrier.

4. The method according to any one of claims 1 to 3, wherein the mass content of accelerator varies from 0.1% to 40% by weight, preferably from 0.5% to 20% by weight, relative to the weight of the carrier.

5. The method according to any one of claims 1 to 4, wherein the low-temperature plasma is a plasma generated by a dielectric barrier discharge (DBD), preferably in a DBD plasma reactor.

6. The water vapor (H ２ 6. The process according to any one of claims 1 to 5, wherein the molar ratio of carbon monoxide (CO) to carbon monoxide (CO) varies between 1 and 5, preferably between 1 and 3.

7. Steps below: a) H as a discharge gas ２ activating said catalyst located between electrodes of a low-temperature plasma reactor, preferably a DBD plasma reactor, by generating a low-temperature plasma under b) introducing the gas mixture to be converted through the catalyst and between electrodes in the reactor; c) converting the gas mixture in the low-temperature plasma according to the WGS reaction by circulating a gas flow between electrodes in the reactor; 7. The method of any one of claims 1 to 6, comprising in order:

8. The following WGS reaction: ++H ２ O→[ ２ +H ２ According to ２ 1. A catalyst for converting a gas mixture containing 1,2,4-trimethylsilyl ... a carrier comprising ceria or cerium oxide, at least one first promoter comprising copper in metallic or oxide form, and at least one second promoter selected from the group consisting of transition metals, post-transition metals, lanthanides, and mixtures thereof, each independently in metallic or oxide form; and a catalyst comprising A catalyst, wherein said catalyst is activated by a low-temperature plasma before contacting said gas mixture to be converted.

9. the catalyst comprises at least 5% by weight, relative to the weight of the carrier, of a promoter comprising copper, and / or the catalyst comprises at least one second promoter selected from the group consisting of zinc, aluminum, and mixtures thereof, each independently in metallic or oxide form; The catalyst according to claim 8.

10. 10. A catalyst according to claim 8 or 9, comprising at least one second promoter consisting of zinc in metallic or oxide form.

11. Catalyst according to any one of claims 8 to 10, wherein the mass content of promoter varies from 0.1% to 40% by weight, preferably from 0.5% to 20% by weight relative to the weight of the carrier.

12. The catalyst of any one of claims 8 to 11, wherein the catalyst and the promoter form a homogeneous mixture.

13. The following WGS reaction: ++H ２ O→[ ２ +H ２ According to ２ 1. Use of a catalyst and a low-temperature plasma for converting a gas mixture containing O, said catalyst comprising: a carrier comprising ceria or cerium oxide, at least one first promoter comprising copper in metallic or oxide form, and at least one second promoter selected from the group consisting of transition metals, post-transition metals, lanthanides, and mixtures thereof, each independently in metallic or oxide form; Including, Use wherein the catalyst is activated by low-temperature plasma before contacting it with the gas mixture to be converted.

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