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    • 专利摘要:
    Procedure of direct reduction of a material by microwave radiation. The present invention relates to the reduction of materials at low temperatures (<600ºC) by microwave radiation without the need to use chemical reducing agents or electrical contacts, more particularly to a process for the reduction of a material, comprising the following steps: - apply microwave radiation to the material arranged in a microwave applicator cavity and - simultaneous separation of the oxidation fluid products generated from the reduced material and such that the procedure is carried out without reducing chemical agents and without electrical contacts. (Machine-translation by Google Translate, not legally binding)
    公开号:ES2726028A1
    申请号:ES201930189
    申请日:2019-02-28
    公开日:2019-10-01
    发明作者:Alfaro José Manuel Serra；Civera José Manuel Catala；Banos Beatriz Garcia；Morell Juan Francisco Borras
    申请人:Consejo Superior de Investigaciones Cientificas CSIC；Universidad Politecnica de Valencia；
    IPC主号:
    专利说明:

    [0001]
    [0002]
    [0003]
    [0004] Field of the Invention
    [0005]
    [0006] The present invention pertains to the field of the use of electromagnetic radiation, more specifically microwave radiation, used in the reduction of materials without the need to use chemical reducing agents and the combined production of chemical products.
    [0007]
    [0008] Background of the invention
    [0009]
    [0010] The future of sustainability depends on a complete renewable energy system, driven by the availability of currently economical energy. The volatile nature of renewable energy requires new efficient ways of storing and converting energy, as well as the rational use of electricity.
    [0011]
    [0012] The transformation of energy systems from fossil sources to renewables with the aim of improving sustainability and mitigating the CO 2 footprint is one of the main challenges facing both the energy sector and the process industry.
    [0013]
    [0014] Due to the volatile and intermittent nature of electricity from renewable energy sources, a way of storing energy in production peaks is required, so that they will be used in production valleys, thus maintaining efficient grid stability in Demand fluctuations function. Likewise, the process industry requires new, more efficient methods that allow the realization of different unit processes, for example, chemical conversion units or molecular separation units, through the direct use of electricity (renewable) instead of mainly thermal processes based on the combustion or oxidation of hydrocarbons from fossil or renewable sources.
    [0015]
    [0016] Energy conversion and storage (ECS) is a key concept based on the absorption of excess renewable energy to generate chemical energy carriers in the form of fuel (hydrogen, methane or others) or chemicals. Current methods for ECS are electrochemical cells that function as electrolysers (for example, PEM EC, proton-exchange membrane electrolyser cell or SOEC - solid oxide electrolyser cell -, which produce fuel and electricity raw materials) or as electrolytic fuel cells solid (SOFC, that produces electricity from fuel), separators based oxygen solid electrolytes (SEOS - solid electrolyte separator oxygen -, oxygen generator electrically driven) or thermal methods (concentrated solar energy, CSP or waste heat) to obtain the chemical energy carriers. This Power to X (PtX) transformation could be further extended for the production, not only of O 2 , H 2 or hydrocarbons, but also of advanced alkaline fuel cells, synthesis of ammonia or nitrides as energy storage material.
    [0017]
    [0018] However, the thermal and / or electrical energy required in these processes is very high.
    [0019]
    [0020] In some cases these transformations, such as the reduction of materials, can be carried out at high temperatures and / or using contact electrodes, which adds a lot of complexity to the installation, resulting in a very high investment (CAPEX), a difficult control and very difficult operation of the process, in addition to very high operating costs (OPEX) and low energy and mass efficiencies.
    [0021]
    [0022] Microwave processing has shown clear advantages over conventional heating in many scientific and technological fields. This technology has become an effective and efficient method for processing a variety of materials such as ceramics, composites, metals, catalysts and other reaction systems [Zhou et al., 2016]. The ultra-fast microwave interaction with the materials, and in particular the microwave interaction at high temperatures, can create new reaction pathways and processes that are not possible using other irradiation methods.
    [0023]
    [0024] In the document Catala-Civera et al., Dynamic Measurement of Dielectric Properties of Materials at High Temperature During Microwave Heating in a Dual Mode Cylindrical Cavity. IEEE Trans. Microw. Theory Tech. 2015, 63, 2905-2914, describes a microwave cavity and a heating system for microwave processing and dynamic measurements in situ of permittivity. However the equipment described in this article presents essential differences with the equipment described in the present invention, for example, among others, the fact that it has no capacity to evacuate substances.
    [0025]
    [0026] The present invention manages to solve these problems of the state of the art. With the microwave-assisted process of the present invention, it has been possible to reduce materials that otherwise would not have been possible. In addition, the reduction of materials is carried out by means of new equipment that achieves the electrochemical activation of materials for the chemical reaction and the production of chemical products, such as O 2 and CO, and energy carriers, such as H 2 , the reduced anode of a battery The interaction of microwaves with the inherent nature of the materials is used to produce a reduction of said materials at temperatures never observed for this type of materials, even in some cases, below 300 ° C.
    [0027]
    [0028] Description of the invention
    [0029]
    [0030] The present invention relates to the direct reduction of materials at low temperatures (<600 ° C) by microwave radiation without the use of chemical reducing agents or electrical contacts.
    [0031]
    [0032] The term "microwave" refers to a non-ionizing electromagnetic radiation that occupies in the electromagnetic spectrum a frequency band located between the infrared and the radio frequencies.
    [0033]
    [0034] The term "reduce a material" is understood as the decrease in the oxidation state of at least part of the cations that constitute the material. The material directly absorbs microwave radiation without the need for other additives for absorption and electronic transfer, such as organic molecules, polymers, metals or metal alloys.
    [0035]
    [0036] The term "firing temperature" is understood as the temperature at which a sharp change in the electrical conductivity of the material is identified due to the activation of charge carriers in the material, which results in the reduction of microwave-processed material.
    [0037]
    [0038] The present invention relates to a process for the reduction of a material, which comprises performing the following operations:
    [0039] - apply microwave radiation to the material arranged in a microwave applicator cavity,
    [0040] - heating up to at least a firing temperature in the material - separating the generated oxidation fluid products from the reduced material and such that the process is carried out without reducing chemical agents.
    [0041]
    [0042] The process of the invention is carried out without electrical contacts.
    [0043]
    [0044] In the process of the invention the operations mentioned in the above definition, and according to claim 1, do not have to be carried out in the order indicated. That is, it is not a chronological order, they can be performed in the order cited or in another order.
    [0045]
    [0046] According to preferred embodiments, the process is carried out in a container that has the ability to evacuate fluids.
    [0047]
    [0048] The increase in temperature by itself produces an increase in conductivity. At the firing temperature there is an abrupt change in conductivity, much more important than the mere effect of the increase in conductivity due to the increase in temperature. This is due to the sudden increase in the conduction of electronic carriers caused by microwave radiation.
    [0049]
    [0050] The microwave radiation application is maintained until a temperature increase of between 50-200 ° C, and preferably between 50 and 100 ° C, is achieved above the firing temperature.
    [0051]
    [0052] "Suddenly" or "sharply" means in this context that the conductivity is increased by at least 4% in a temperature increase of 4 degrees Celsius
    [0053]
    [0054] In the process of the invention, the electrical conductivity of the material is increased by at least 50% with respect to the conductivity of the material without reducing, as the temperature is increased by 4 ° C.
    [0055]
    [0056] In the reduction of the material, a product resulting from the oxidation of the anion associated with the cation is released, which is reduced. The oxidation product is often an unstable product. However, this oxidized product may have "in situ" utility.
    [0057] According to particular embodiments, the evacuated oxidation product is O 2 , O 3 , CI 2 , F 2 , Br 2 , CO 2 , SO 3 or mixtures thereof. When solid oxides are reduced, for example, O 2 is released, in the case of chlorides, Ch is released, in the case of sulfides S is released, etc.
    [0058]
    [0059] If said oxidation product is not evacuated from the container in which the material is inside the cavity, when the microwave radiation ceases, it generally reacts again with the material and re-oxidizes it, to return it to its original state.
    [0060]
    [0061] The materials that can be reduced by the process of the invention can be in solid state, in molten state, suspended or dissolved in a fluid. Said fluid can be, for example, water (for example, water in a liquid or supercritical state) or a hydrocarbon capable of being in a liquid state under the conditions of the process (for example, paraffins, waxes, oils).
    [0062]
    [0063] For the phenomenon of reduction through absorption of microwave radiation to occur under conditions of practical industrial use (for example, below 600 ° C), the material to be reduced must meet certain characteristics:
    [0064]
    [0065] - The material must have crystalline or amorphous form, cations that can be reduced. The reduction of the material takes place through the reduction of specific metal cations of elements selected from Ti, Fe, Co, Zr, Cr, Nb, Ta, W, Mo, rare earths and U (for example: Ce + 4, Ti +4, Zr + 4, W + 6, Pr + 4, Nd + 3, Nb + 5) which consequently results in the oxidation of its counter-anion to form a product that can be evacuated.
    [0066] - In solids, for a homogeneous reduction of the solid (inside and outside of the grains) it is advantageous to have a certain degree of ionic conductivity (for the specific anion that oxidizes), so that the anion can diffuse through the grain of the solid towards outside to release after oxidation.
    [0067] - In the case of extended solids (nanoparticles or with a high surface area), the ionic conduction property is not advantageous since the ionic solid-state stage at the microscopic level within each grain of material is not necessary.
    [0068]
    [0069] According to additional particular embodiments, the simultaneous separation of fluid oxidation products, generated from the reduced material is carried out by one of the following means or combinations thereof:
    [0070] - the application of vacuum,
    [0071] - the use of a drag fluid,
    [0072] - use of a reactive fluid that consumes it or
    [0073] - use of a selective separator of the generated oxidation product.
    [0074]
    [0075] The process of the invention may further comprise a step of in-situ measurement of the conductivity of the material to be reduced by applying microwave radiation from a second source and an associated receiver without mutual inferences. This stage or operation of in-situ measurement of the conductivity of the material to be reduced can be performed during the whole procedure, it does not have to be a previous stage.
    [0076]
    [0077] The in-situ measurement of the material firing temperature can be carried out through measurements of conductivity of the material to be reduced and the temperature of the material.
    [0078]
    [0079] The method of the invention also considers, according to particular embodiments, the in-situ and continuous measurement of the firing temperature of the material through measurements of conductivity and the temperature of the material.
    [0080]
    [0081] Above the "firing temperature" the reduction process occurs when applying microwave radiation in a device that allows the control of the homogeneity in the radiation in the material and control of the applied power, thus preventing heterogeneities and possible deterioration of the material.
    [0082]
    [0083] During the reduction procedure, a continuous adjustment of the microwave power applied for irradiation can be carried out, with the purpose of optimizing the power transfer because the electrical conductivity of the material changes with temperature. Continuous adjustment of the applied power implies an improvement in the amount of material reduced.
    [0084]
    [0085] The control of irradiation and microwave power is essential in the process.
    [0086] The method of the invention further comprises, according to particular embodiments, while performing radiation a continuous adjustment of the power applied for irradiation.
    [0087]
    [0088] The process of the invention comprises, according to additional particular embodiments, the following steps:
    [0089] - place the material in a container capable of evacuating fluids, and inert to MW radiation,
    [0090] - Insert the container through a hole located in a wall of the applicator cavity in a uniform and intense electric field area (preferably as intense as possible) for uniform and efficient heating
    [0091] - identify the “firing temperature” for that material,
    [0092] - apply microwave radiation until the material is reduced,
    [0093] - heat up to at least exceed the firing temperature in the material - carry out while the radiation is applied a continuous adjustment of the applied power for irradiation and
    [0094] - separating the generated oxidation fluid products from the reduced material and such that the process is carried out without reducing chemical agents.
    [0095]
    [0096] The present invention further relates to an equipment (Figure 1) for carrying out the procedure defined above, comprising:
    [0097] - at least one source of microwave radiation (1),
    [0098] - a microwave applicator cavity (2), and
    [0099] - a container (3) in which the material (4) is deposited, which is to be reduced.
    [0100]
    [0101] The equipment may also include:
    [0102] - at least one temperature sensor (5) to measure the temperature of the material during microwave application (6)
    [0103] - at least one means for the evacuation of the fluids (7) originated during the reduction procedure.
    [0104]
    [0105] The source of microwave radiation (1) for irradiation may be a microwave generator based on a magnetron or a microwave generator based on a solid state amplifier.
    [0106] The microwave radiation source (1) can operate at frequencies between 300 MHz and 300 GHz. For example, according to particular embodiments the microwave radiation source (1) operates at frequencies 915 MHz, 2450 MHz or 5800 MHz, frequencies intended for applications industrial, scientific or medical that do not require a private license (called ISM frequencies “Industrial Scientific and Medicar).
    [0107]
    [0108] The equipment may comprise a power isolator (9) to protect the source of microwave radiation against the power reflected from the applicator cavity (2).
    [0109]
    [0110] The applicator cavity (2) can be a microwave resonator, if the necessary microwave radiation intensity is high. In addition, the microwave resonator may have a cylindrical, polyhedral (prismatic, for example) or spherical shape.
    [0111]
    [0112] Microwave radiation (6) is introduced into the applicator cavity (2) through a waveguide, or through an coupling or opening (10) in one of its side or upper / lower walls.
    [0113]
    [0114] According to particular applications, the coupling (10) for introducing microwave radiation into the applicator cavity is based on an electric probe, a magnetic probe (current loop) or an opening in one of the walls (lateral, upper and lower).
    [0115]
    [0116] The applicator cavity (2) can have at least one non-radiant hole located in the upper wall and a second non-radiant hole located in the lower wall (11), which allow the passage of substances, in particular, the introduction and evacuation of gases (7).
    [0117]
    [0118] The container (3) that is disposed within the cavity must be of an inert material, that is to say that it does not absorb microwaves, that does not react with the material that is to be reduced and that supports the maximum temperatures of the electrochemical process. Said container can be, for example, a quartz tube, or alumina, microwave inert materials and capable of withstanding high temperatures (> 600 ° C). In addition, the container (3) must allow it to work in contact with different chemicals, generally in the form of gases.
    [0119]
    [0120] According to a particular embodiment, the container (3) comprises a porous medium that acts as a mechanical support (12) on which a solid state material (4) is held. It radiates. Examples of supports: porous ceramic (fried) membranes, ceramic foams, fiber meshes or felts, or microperforated plates.
    [0121]
    [0122] The applicator cavity (2) can comprise an access hole (13) in the side wall that allows measuring the temperature of the surface of the material or of the container it contains in material located inside. It can be measured, for example, by an infrared thermometer (5) placed outside the cavity.
    [0123]
    [0124] According to additional particular embodiments, the applicator cavity (2) comprises an additional coupling (14) of a second source of low power microwave radiation (15) and receiver associated with the purpose of performing in-situ and simultaneous conductivity measurements. Said second source is protected from interference with the first source of radiation.
    [0125]
    [0126] Also optionally, the cavity may have additional holes (16) for arranging recording media, such as video cameras for observation of the material during the reduction process.
    [0127]
    [0128] These holes, and in general, the holes in the cavity have dimensions, and are positioned, to ensure that they do not disturb the fields or the resonances of both resonant modes, and to prevent microwave leaks.
    [0129]
    [0130] Also optionally, the cavity can have means for the analysis (8) of the composition of the products released in the reduction process, and that facilitate the control and operability of the entire process.
    [0131]
    [0132] The equipment can also comprise a mass spectrometer (8) for the analysis of gases produced during microwave radiation. The equipment may also comprise means for evacuating fluids (7) originated during the reduction process, such as means for applying vacuum, or means for dragging fluids, or means for circulating reactive fluids that consume the fluid generated during The reduction.
    [0133]
    [0134] The equipment may also comprise a water cooling system (17).
    [0135] According to a particular embodiment of the equipment for microwave material reduction according to the method of the invention, the equipment (figure 5) comprises a microwave applicator cavity (2), a microwave generator (1), an insulator to protect the microwave generator ( 9), a container (3) to introduce the material to be reduced (4), a sensor to measure the temperature (5) of the container (3) and material (4) from outside the cavity (2) and a system ( not included in figure 5) for the evacuation of fluids (7) originated during the reduction procedure.
    [0136] The microwave applicator cavity (2), according to a particular embodiment, is designed as a cylindrical microwave resonator to be able to radiate materials with low and high dielectric losses of the material itself with the same cavity.
    [0137]
    [0138] The configuration of the electromagnetic field for microwave irradiation exhibits a uniform and intense electric field in the center of the resonator cavity, where the sample (4) is placed, as corresponds to a configuration of the TE111 electrical transverse resonant mode.
    [0139]
    [0140] The cylindrical irradiation mode TE111 is selected to have a resonance around the ISM frequency of 2.45 GHz, which facilitates its application or subsequent industrial realization. The dimensions of the cavity are carefully designed to avoid interference from other resonant modes. These cavity dimensions can be modified to have the equivalent resonant mode TE111 around additional ISM frequencies, also available for industrial use (for example, 0.915 GHz, 5.8 GHz, etc.).
    [0141]
    [0142] The power microwave signal (microwave radiation) to irradiate the material is introduced into the resonant cavity (2) (applicator cavity) through an electrical probe placed on the side wall through an coupling (10) with a connector on N (internal diameter ~ 3 mm).
    [0143]
    [0144] The microwave irradiation source (1) can be a solid state amplifier driven by the RF output of a vector network analyzer or a microwave generator (1) based on a magnetron.
    [0145]
    [0146] At the exit of the microwave source (1) a power isolator (9) is normally placed to protect the source against the power reflected from the cavity.
    [0147] In this particular embodiment, the sample volume of material (4) to be reduced is set at 10 mm in diameter and 15 mm in height, according to the electric field in the cavity.
    [0148]
    [0149] The material is placed inside a container (3), on a porous membrane to hold the sample (figures 1 and 5), while allowing the flow of gases due to its porosity.
    [0150]
    [0151] The sample container (3) is a quartz tube (internal diameter ~ 10 mm, external diameter ~ 12 mm), capable of withstanding high temperatures (~ 1300 ° C). The container (3) is introduced into the microwave applicator cavity (2) through one or several non-radiant holes (11) located in the upper and lower walls until the material is located in the center of the cavity, in the position of maximum electric field strength, to ensure uniform sample processing. In addition, this allows intense and very efficient irradiation cycles.
    [0152]
    [0153] These holes (11) allow the introduction and evacuation of gases through the container.
    [0154]
    [0155] In this particular embodiment, the inlet tube to the container (3) would be connected to a gas supply conduit and the outlet (11) would be connected to an inlet conduit to a gas analyzer (8), such as a spectrometer mass (8). Once the inlet gas flows through the material in steady state, microwave radiation is applied and the reduction of the material (4) occurs, which is fixed in a supported bed (12), so that an oxidizing gas is released . Said gas is carried by a carrier gas and is extracted through a fluid evacuator (7), and finally analyzed by a mass spectrometer (8).
    [0156]
    [0157] To avoid thermal expansion of the cavity during operation, the temperature of the cavity resonator can be optionally controlled by a water cooling system (17).
    [0158]
    [0159] The automatic operation of the microwave radiation process is done by connecting the analyzer to a computer with a GP-IB link.
    [0160]
    [0161] An infrared thermometer (5) is used to measure the temperature of the sample surface (4) to be reduced from the outside of the cavity through a cut-out hole (13) 7 mm in diameter located on the side wall of the cavity. Another hole (16) of 7 mm is used to place a video camera to observe the sample to be reduced during microwave radiation. The dimensions and positions of the access holes in the cavity were designed to ensure that they do not disturb the fields or the resonances of both modes, and to prevent microwave leaks.
    [0162]
    [0163] For a correct and continuous determination of the temperature of the material irradiated by microwave through the measurement of the surface temperature of the material with a temperature sensor (5), specifically an infrared pyrometer, a calibration procedure based on the introduction of reference samples with controlled temperature and the measured temperature from the surface has been adjusted.
    [0164]
    [0165] The microwave driven reduction mechanism requires specific irradiation conditions. In order for the reduction to take place, it is necessary to reach the “firing temperature” and above it there is always the reduction process when applying microwave radiation properly. Properly means without damaging the material by excessive application of power.
    [0166]
    [0167] This firing temperature in the material is identified by an abrupt change in electrical conductivity. The change in electrical conductivity is also manifested in a sharp increase in microwave absorption and material temperature.
    [0168]
    [0169] In this particular embodiment, the firing temperature can be identified from the measurement of the conductivity of the material to be reduced and this identification test of said temperature can also be carried out in the same cavity of Figure 5 and simultaneously with the radiation with microwave, with the additional advantage of eliminating the need for physical contact with the sample.
    [0170]
    [0171] In this particular embodiment, for the measurement of conductivity of the material to be reduced in the applicator cavity of Figure 1, an electrical coupling (14) has been added to the bottom wall of the applicator cavity using an SMA connector (internal diameter ~ 1, 5 mm) and a second low power microwave source and a microwave receiver have been installed around the frequency of 2.1 GHz, to power a second mode TM010 resonant that can coexist with the main microwave radiation mode in the TE111 cavity without interference.
    [0172]
    [0173] An additional filter can be placed in the measurement coupling of the receiver to provide a high level of isolation greater than 100 dB that guarantees the safety of all simultaneous operations.
    [0174]
    [0175] The automatic operation of these measurements is also done by connecting the analyzer to a computer with a GP-IB link.
    [0176]
    [0177] In this particular embodiment, the electrical conductivity is calculated using the MCPT (Perturbation Cavity Microwave) technique, where the depolarization of the electric field in the sample is taken into account.
    [0178]
    [0179] The container (3) allows the extraction or evacuation of the released element (oxidized substance generally in the form of gas or liquid), for example, by the application of vacuum, the use of a entrainment fluid, the use of a reactive fluid that consume or use a selective separator of the released element, or combinations thereof. If said element is not evacuated from the container in which the material is inside the cavity, when the microwave radiation ceases, it generally reacts again with the solid and re-oxidizes it, to return it to its original state (as regards to its energetic, morphological, crystalline or compositional state).
    [0180]
    [0181] In a particular case (refers to the one explained above, where he describes Figure 13A), the material may not be fixed in the container and enter and exit as a fluid, as is done industrially in processes of catalytic reactors of mobile bed or columns adsorption mobiles. In that case, the oxidized element released after the application of the microwave radiation is evacuated mixed with the reduced material and there would be a rear separator, for example, type cyclone separator or porous filter, depending on the specific state of the reduced material. In this particular case, the evacuation and separation of the reduced material would necessarily be carried out at high speed to limit the re-oxidation of the reduced material in contact with the element released in the absence of microwave radiation.
    [0182]
    [0183] This reduction procedure is technically simpler than the techniques known so far, since only microwave radiation and control are required of the fluid (composition and dynamic fluid), generally using vacuum or a carrier gas. Otherwise, the reduction requires very high temperatures (> 1000 ° C, depending on the material) and use of chemical reducing agents such as H 2 , CO or solid carbon, with a very high process complexity, safety risks and high costs of production.
    [0184]
    [0185] The process of re-oxidation of the material with a molecule, such as: O 2 , H 2 O, Cl 2 , F 2 , HF, HCl, H 2 S, N 2 O, NOx or CO 2 , which contains an atom liable to be reduced and incorporated into the structure of the material does not need a minimum temperature, but the re-oxidation will be complete and rapid above the "firing temperature".
    [0186]
    [0187] Depending on the application, it is necessary to use one material or another, to adjust the kinetics of the process, the stability of the material to “microwave cycling”, the reduction capacity, the selectivity to one oxidizing molecule or another and the catalytic activity for the reactions (typically between a solid and a fluid, or at the interface between fluids). In the election, the energy needs in the reduction cycles must also be considered as oxidation, so that the release or consumption of heat in both processes is controlled (usually minimized).
    [0188]
    [0189] In another particular embodiment (Figure 3A), the gas formed (oxidized fluid) is evacuated mixed with the material to be reduced and there is a rear separator outside the applicator cavity, which separates the reduced solid material from the oxidized gas stream, for example, cyclone separator type or porous filter. The material to be reduced (4) could flow continuously, as a liquid or solid particles in a moving fluid, through the container, as occurs, for example, in industrial systems such as FCC ("fluid catalytic cracking") , chemical looping systems or fluidized bed reactors with drag. (Figure 3A) Figure 4 shows a process in which it performs the complete cycle of reduction induced by microwave radiation and merely chemical oxidation of the material that takes place in different units, so that it is the material that circulates along the redox chemical cycle
    [0190]
    [0191] Alternatively, a selective separator can be integrated inside the cavity that separates, from the rest of the circulating fluid, the oxidized element released through the reduction of the material by the application of the microwaves (Figure 3B).
    [0192] The present invention further relates to a reduced material obtained by the process defined above.
    [0193]
    [0194] The present invention further relates to the use of the process defined above, or of the material reduced by the process of the invention, in industrial, agricultural or medicinal processes.
    [0195]
    [0196] According to a particular use, the reduced material is used as a selective absorbent for
    [0197] Treat a gas stream.
    [0198]
    [0199] According to an additional particular use, the industrial process is the selective removal of a
    [0200] gas, such as O 2 , O 3 , Ch, F 2 ,
    [0201] able to react with impurities (for example, O 2 , O 3 , Ch, F 2 , Ch, Br 2 , HCl, HBr,
    [0202] HF, H 2 S, N 2 O, NOx or mixtures thereof) and fix them in its crystalline structure. This "absorbent" material is regenerated instantly with microwave radiation.
    [0203]
    [0204] The industrial process can be the generation of a chemical product through the reaction of the material in a reduced state and a second organic molecule - oxidized molecule - capable of being reduced, to form products with new functional groups. The oxidized molecule can be CO 2 and the product obtained from the reaction
    [0205] of the oxidized molecule and the reduced CO material. The oxidized molecule can also
    [0206] be selected from H 2 O and H 2 S and the product obtained from the reaction of the oxidized molecule and the reduced material is H 2 . The oxidized molecule can be a mixture of
    [0207] gases containing H 2 O and CO 2 that reacts with the material in a reduced state, to
    [0208] directly form hydrocarbon products (such as alkanes, olefins, aromatic compounds, alcohols or other oxygenated hydrocarbons).
    [0209]
    [0210] An additional particular use of the process is the generation of an oxidizing molecule, using the product resulting from anion oxidation, for example, to produce O 2 , Ch, F 2 , Br 2 , S, etc. The generation of said molecules induced by microwave radiation can be carried out in a chemical reactor for the oxidation of hydrocarbons or other molecules (type Chemical looping) in which an oxidizing molecule is generated in situ (for example, O 2 or Br 2 ), so that its generation is avoided
    [0211] in another installation or unit and, at the same time, the concentration of said oxidizing molecule in the reactor can be controlled and avoid exceeding explosive limits or flammability, while achieving high selectivity in the target oxidation reaction.
    [0212]
    [0213] A further particular use of the process is the generation of a chemical through the reaction of the material in a reduced state and a molecule chosen from alkanes, alkenes, naphthenes and aromatic hydrocarbons, to form products with new functionalities. The functionalization or activation of hydrocarbons, such as methane or ethane to give olefins, hydrogen, synthesis gas or aromatic hydrocarbons, is thus achieved.
    [0214]
    [0215] The term "activation" refers to breaking a C-H bond in a saturated hydrocarbon, so that a function can be incorporated into that C-, and as a result the molecule is more active (or reactive) and has new functional groups.
    [0216]
    [0217] The hydrocarbons are functionalized, for example, by some type of oxidation, where the reaction products are usually olefins, alkynes, aromatic and oxygenated compounds (alcohols, ketones / aldehydes, acids, etc.).
    [0218]
    [0219] According to an additional particular use, the industrial process is the activation (ON-OFF) of a material, for example, for sensors, such as magnetic elements, electronic elements, etc. so that by changing their state of reduction their properties can be adjusted catalytic for a given reaction. In this case the material is reduced or oxidized depending on whether it is ON or OFF. A particular example of this use is the activation of ZrO 2 , Nb 2 O 5 , etc. whose activation at low temperatures without chemical reducing agents is not possible. Through this industrial process it is possible to induce electronic conductivity in materials or components, so that it can be used in sensors, gas separation membranes ( mixed ionic electmnic conducting membranes), security systems, telecommunications, etc.
    [0220] According to an additional particular use, the material reduced by the effect of microwave radiation, obtained by the process of the invention is used for energy storage in the reduced material.
    [0221]
    [0222] According to an additional particular use the reduced material is used for rapid recharging of batteries thanks to the selective reduction of material comprised in the negative electrode and the simultaneous evacuation of the oxidation product. That is, the storage of energy in the reduced material: batteries to recharge Instantly by microwave or chemical storage for future use in chemical reactors. One embodiment refers to the batteries called Metal-Air, in which the anode is recharged by microwave reduction, the generated O 2 is evacuated from the anode chamber, and during the use of the battery (discharge), the anode is it is discharging through the diffusion of ions, for example, oxygen ions through a selective electrode (for example CeO 2 or ZrO 2 doped) and producing in the anode electrons with a greater potential, which will circulate through the external circuit (the Battery charge. Another alternative for application in Metal-Air batteries is the use of electrolytes based on protonic conductors in combination with the reduction in situ of H 2 O.
    [0223] According to an additional particular use, the industrial process comprises obtaining a product selected from O 2 , H 2 , O 2 extraterrestrial - in remote locations or on space missions using extraterrestrial minerals -.
    [0224]
    [0225] The present invention further relates to a method of using the process defined above, or method of using the reduced material by the process of the invention, in industrial, agricultural or medicinal processes.
    [0226]
    [0227] According to a particular embodiment, said method comprises contacting the reduced material with a gas stream and performing a selective absorption of one or more components of the gas stream.
    [0228]
    [0229] According to a further particular embodiment, said method comprises contacting the reduced material with a gas stream and performing a selective removal of a gas, such as, for example, O 2 , O 3 , Ch, F 2 , Ch, Br 2 , HCl, HBr, HF, N 2 O, NOx, H 2 S or mixtures thereof, of the gas stream. It is done using the material in a reduced state, which is capable of reacting with impurities (for example, O 2 , O 3 , Ch, F 2 , Cl 2 , Br 2 , HCl, HBr, HF, H 2 S or mixtures of them) and fix them on its crystalline structure. This "absorbent" material is regenerated instantly with microwave radiation.
    [0230]
    [0231] According to a further particular embodiment, said method comprises carrying out a reaction of the material in a reduced state and a second organic molecule - oxidized molecule - capable of being reduced, and generating a chemical with new functional groups. The oxidized molecule may be CO 2 , or it may be H 2 O and H 2 S, or it may be a mixture of gases containing H 2 O and CO 2 and the corresponding products will be those indicated above.
    [0232] According to a further particular embodiment, said method comprises using the product resulting from oxidation of the anion and generating an oxidizing molecule, which can be, for example, O 2 , Ch, F 2 , Br 2 , S, etc.
    [0233]
    [0234] According to a further particular embodiment, said method comprises carrying out a reaction of the material in a reduced state with a molecule chosen from alkanes, alkenes, naphthenes and aromatic hydrocarbons, to form products with new functionalities.
    [0235]
    [0236] According to a further particular embodiment, said method comprises carrying out the activation (ON-OFF) of a material, for example, for sensors, such as magnetic elements, electronic elements, etc. so that by changing their reduction state they can be adjusted its catalytic properties for a given reaction.
    [0237] Throughout the description and the claims the word "comprises" and its variants are not intended to exclude other technical characteristics, additives, components or steps. For those skilled in the art, other objects, advantages and features of the invention will be derived partly from the description and partly from the practice of the invention.
    [0238]
    [0239] Brief description of the Figures and references used in the figures:
    [0240]
    [0241] (1) Microwave radiation source
    [0242] (2) Microwave applicator
    [0243] (3) Container in which the material to be reduced is deposited
    [0244] (4) Sample of material to be reduced
    [0245] (5) temperature sensor
    [0246] (6) Microwave radiation
    [0247] (7) Devices for fluid extraction or separation, fluid evacuator (for example, gases)
    [0248] (8) Means of analysis
    [0249] (9) Power Isolator
    [0250] (10) Coupling to introduce power microwaves
    [0251] (11) Cut-out hole to introduce container container material to be reduced (12) Support for material to be reduced
    [0252] (13) Hole for measuring surface temperature of the material to be reduced (14) Coupling (optional) for in-situ conductivity measurement
    [0253] (16) Hole (optional) for process observation.
    [0254] (17) Water cooling system.
    [0255]
    [0256] Figure 1: Scheme of the configuration of the equipment to reduce a material through microwave radiation treatment.
    [0257]
    [0258] Figure 2: Scheme of the applicator cavity and additional components to reduce a microwave material.
    [0259]
    [0260] Figure 3: Scheme of an embodiment in which the material (4) to be reduced is continuously fed: A) scheme of the applicator cavity (2) plus components followed by a separator (7) of the gas produced in the reduction with respect to to the reduced material and B) scheme of the applicator cavity (2) plus components that integrate within the cavity (2) a selective separator of the gas produced in the reduction.
    [0261]
    [0262] Figure 4. Scheme of an embodiment in which the material (4) to be reduced is continuously fed which integrates a process in which it performs the complete cycle of reduction induced by microwave radiation (6) and merely chemical oxidation of the material (4) that takes place in different units, so that it is the material (4) that circulates throughout the redox chemical cycle.
    [0263]
    [0264] Figure 5: Particular implementation of the reduction process in a microwave applicator (2) configured as a cylindrical cavity.
    [0265]
    [0266] Figure 6: Arrhenius diagram of electrical conductivity for CGO material with and without microwave application.
    [0267]
    [0268] Figure 7: Temporary evolution of the electrical conductivity, temperature and ion current (m = 32) during microwave application to the CGO material.
    [0269]
    [0270] Figure 8: Temporal evolution of the electrical conductivity and ion current (m = 32) during microwave application to the CGO material under a nitrogen gas stream.
    [0271]
    [0272] Figure 9: Arrhenius diagram of electrical conductivity for porcelain material with and without microwave application.
    [0273]
    [0274] Figure 10: Temporary evolution of the electrical conductivity and temperature during the Microwave application to porcelain material.
    [0275]
    [0276] Figure 11: Arrhenius diagram of electrical conductivity for 8YSZ material with and without microwave application.
    [0277]
    [0278] Figure 12: Temporary evolution of the electrical conductivity and ion current (m = 32) during the application of a microwave radiation step to the 8YSZ material.
    [0279] Figure 13: A) Temporary evolution of the temperature and ion current (m = 31.91 and M = 16.03) associated with O 2 , and B) temporal evolution of the electrical conductivity and ion current (m = 31.91) associated with O 2 . In both cases during the same microwave application on the CaTio material. 8 Ugly. 2 O 3 -s with perovskite crystalline structure under constant flow of dry N 2 .
    [0280]
    [0281] Figure 14: A) X-ray diffraction diagrams for the CGO material before and after its reduction by microwave application; B) XPS spectrum for the CGO material before and after its reduction by microwave application
    [0282] Figure 15: A) Temporary evolution of the temperature and ion current (m = 32) associated with O 2 , and B) temporal evolution of the temperature and ion current (m = 2.09) associated with H 2 . In both cases during the same microwave application in three steps followed to the CGO material under a wet Ar flow.
    [0283]
    [0284] Figure 16: A) Temporary evolution of the temperature and ion current (m = 32) associated with O 2 , and B) temporal evolution of the temperature and ion current (m = 28) associated with CO. In both cases during the same microwave application in three steps followed to the CGO material under a flow of CO 2 diluted in dry Ar and free of N 2 .
    [0285]
    [0286] Figure 17: A) Temporal evolution of the temperature and ion current (m = 32) associated with O 2 , B) and C) ion currents (m = 16 and 15) associated with CH 4 , D) ion current ( m = 28) associated with CO, E) ion current (m = 2) associated with H 2 , and F) ion current (m = 44) associated with CO 2 . In all during the same microwave application, with a temporary step-shaped profile, the CGO material under a flow of undiluted, dry and free N 2 CH 4 gas.
    [0287] The present invention is illustrated by the following examples that are not intended to be limiting thereof.
    [0288]
    [0289] EXAMPLES
    [0290]
    [0291] Example 1
    [0292]
    [0293] In a process of irradiation of a sample by microwave, the resonant cylindrical cavity of Figure 5 is used. The sample consists of 3 g of cerium oxide doped with gadolinium CGO (Ce 0. 8 Gd 0. 2 O 19 ) which is located in the form of granules on a support (12) inside the applicator cavity (2). A nitrogen gas stream (with 100 mL / min flow under normal conditions) (0 ° C and 1 atm) flowing through the material is applied and microwave radiation (power around 100 W) is applied so that the temperature increases progressively until reaching a firing temperature at which the reduction of the material is produced accompanied by the release of gaseous O 2 . This process has been monitored through the electrical conductivity measurement shown in Figure 6, where there is a sharp jump in conductivity at a firing temperature 136 ° C with an increase in conductivity of ~ 18% at 4 ° C . This sharp increase is related to an increase in the concentration of electric charge carriers (latones) generated thanks to the partial reduction of the material by the action of microwave radiation. Also, the figure includes the measurement of conductivity when heating occurs by conventional means, electrical resistance and / or infrared radiation. This measure shows the absence of a reduction process, that is, there are no sudden changes in conductivity.
    [0294]
    [0295] The outlet gas of (7) is analyzed by a mass spectrometer (8) of the Pfeiffer Vacuum OmniStar type . Figure 7 shows the measurement of the mass corresponding to oxygen (m = 32) as a function of the time of the experiment. This figure also depicts the temporal evolution of electrical conductivity and temperature as a function of time. It is observed that an oxygen release takes place that starts when a sharp variation in electrical conductivity is detected. This release of molecular oxygen (O 2 ) constitutes an unequivocal proof of the reduction of the material through the application of microwave radiation.
    [0296] Figure 8 shows the results of another type of operation. In this case the microwave radiation is applied and the reduction of the CGO material occurs and the irradiation is maintained so that the reduced material is maintained at a constant temperature. Figure 8 shows the temporal evolution of the electrical conductivity and the measurement of the mass corresponding to oxygen (m = 32) as a function of time. It is observed that, after the reduction and stabilization of the conductivity - at the level corresponding to reduced - it is possible to constantly maintain that level of conductivity until the microwave radiation ceases.
    [0297]
    [0298] Table 1: Effect of the partial pressure of oxygen and the power of the radiation applied during the reduction in the increase in the electrical conductivity of the CGO material, firing temperature and the amount of O 2 released after its reduction by microwave application.
    [0299]
    [0300]
    [0301]
    [0302]
    [0303] Table 1 shows a summary of the key parameters (firing temperature, amount of O 2 gas released and sharp increase in electrical conductivity) in the reduction of the CGO material by microwave when in the gaseous stream that is passed through the material the partial pressure of gaseous O 2 has varied. It is observed that, when the partial pressure decreases, the reduction takes place at lower firing temperatures and more O 2 is released. The increase in electrical conductivity does not seem to change significantly with the partial pressure of O 2 .
    [0304]
    [0305] Even in air, it is possible to detect the release of oxygen by CGO. The oxygen released increases as the pO 2 of the scanning gas decreases, reaching a plateau after pO 2 ~ 10 "4 atm (0.01% O 2 / Ar). The release of oxygen is a function of the MW power applied
    [0306] Table 1 also shows the effect on the key parameters in the reduction of the CGO material when different radiation powers are applied. These results demonstrate that the reduction process can be controlled by adjusting said power. The greater the power of the microwave radiation applied, the greater the conductivity gap. More oxygen can be released and therefore more oxygen vacancies are produced, and the effect is measured in the material's transport properties as a higher level in the sudden increase in conductivity.
    [0307]
    [0308] Example 2
    [0309]
    [0310] On the other hand, there are materials that can be irradiated by microwaves, such as porcelain type materials, which do not exhibit the behavior of the CGO and, therefore, cannot be reduced by microwave radiation according to the present invention. Figure 9 shows the measurement of electrical conductivity for the porcelain material as a function of temperature when microwave radiation is being applied (continuous line in Figure 9) and it can be seen that there is no sharp change in conductivity, that is, There is no reduction in porcelain material and, therefore, there is no firing temperature for this type of materials. This figure also includes the measurement of conductivity when heating occurs by conventional means, electrical resistance and / or infrared radiation. These measurements perfectly coincide with the measurements made by applying microwave radiation, so it is confirmed that for this material the microwaves cannot induce a reduction of the material in the range of operation proposed in the present invention. This behavior is observed both when the material is measured in a tube open to the atmosphere, and when a gas flow is applied, such as streams of Ar, He, N 2 , O 2 , H 2 , mixtures of Ar / O 2 (0.01%, 0.1%, 1.5%) and saturated streams of H 2 O.
    [0311]
    [0312] Figure 10 shows the temporal evolution of the electrical conductivity and the temperature as a function of the test time when the microwave radiation is applied on the porcelain material. It is observed that the temperature increases linearly with time while the conductivity shows a typical thermal activation behavior, but there is no sudden change that can be associated with microwave reduction, as it was observed for the CGO material (Figure 7).
    [0313] Example 3
    [0314]
    [0315] Figure 11 shows Arrhenius's representation of the measured electrical conductivity of 3 g of Yo.i 6 Zro. 86 O 2 -s (8YSZ) irradiated by microwave as a function of temperature (reciprocal) when a gaseous stream was passed in Ar (with flow of 100 mL / min under normal conditions) through said material in the form of granules. As it was seen for the CGO (example 1), a trip temperature of approximately 200 ° C can be identified, in this case, from which there is a strong increase in conductivity with the application of microwaves, followed of a slower increase. This sharp increase in electrical conductivity is related to the reduction of the material that significantly increases the concentration of electronic carriers. This phenomenon is accompanied by the release of O 2 gas (Figure 12) and the formation of oxygen vacancies in the crystalline structure, since the reduction process preserves the integrity of the fluorite structure of the 8YSZ material. It is noteworthy that the reduction of the 8YSZ material, and in particular of the Zr + 4 cations of its structure, is very complex and usually requires very high temperatures (> 1700 ° C) combined with the use of strong chemical reducing agents. It also stands out that after the microwave reduction the fluorite structure is preserved, although the number of oxygen vacancies increases as a result of the reduction. Figure 11 also shows the evolution of the electrical conductivity of the material when microwave radiation is not applied, observing that it presents a curve without an abrupt activation jump and following the expected curve for a pure oxygen ion (O-2) conductor, as It is the 8YSZ material.
    [0316]
    [0317] Figure 12 shows the results of an assay in which microwave radiation is applied and the reduction of material 8 YSZ occurs under dry Ar flow (with flow of 100 mL / min under normal conditions) and irradiation is maintained so that the material is kept reduced at a constant temperature. Figure 12 shows the temporal evolution of the electrical conductivity and the measurement of the mass corresponding to oxygen (m = 32) as a function of time. It is observed that, after the reduction and stabilization of the conductivity - at the level corresponding to reduced - it is possible to constantly maintain that level of conductivity until the microwave radiation ceases and, at that point, an inverse peak is observed (absorption ) in the O 2 signal, which indicates the re-oxidation of the material, even though the O 2 content in the Ar used is below 210-5 bar. This example shows that the present invention will allow the removal of oxygen impurities from gaseous streams at levels even below parts per million (ppm), that is, it will selectively purify gaseous streams.
    [0318]
    [0319] Table 2: Effect of the partial pressure of oxygen and the power of the radiation applied during the reduction, in the increase of the electrical conductivity of the 8YSZ material, firing temperature and the amount of O 2 released after its reduction by means of the microwave application .
    [0320]
    [0321]
    [0322]
    [0323]
    [0324] Table 2 shows a summary of the key parameters (firing temperature, amount of O 2 gas released and sharp increase in electrical conductivity) in the reduction of 8YSZ material by microwave when in the gas stream (with flow of 100 mL / min under normal conditions) that passes through the material the partial pressure of gaseous O 2 has been varied. It is observed that the amount of O 2 released increases as the partial pressure of O 2 decreases.
    [0325]
    [0326] The temperatures at which the difference in conductivity between the conventional process and the microwave are maximum, is 361 ° C for 8YSZ (example 3) and 216 ° C for CGO (example 1). The difference between the materials may be related to the reducibility of their cations, since the presence of the Ce3 + / 4+ pair is easier to achieve, than for YSZ the Zr3 + / 4+ pair.
    [0327]
    [0328] Example 4
    [0329]
    [0330] Following the procedure described in example 1, several materials based on doped cerium oxide were reduced as follows: microwave radiation was applied at a power in the range of 25-75 W within the system described in example 1 by passing Ar through the material. Various materials of cerium oxide without doping and doped with Gd (10 and 20 mol.%), Pr (20 mol.%) and (Gd 10
    [0331] mol. % and Nb 4%), all of them have the crystalline structure of cubic fluorite. The
    [0332] Table 3A shows a summary of the key parameters (firing temperature,
    [0333] amount of O 2 gas released and sharp increase in electrical conductivity) in the
    [0334] reduction of the different materials by microwave when through the material
    [0335] A gas stream is passed with a flow of 100 mL / min under normal conditions. Be
    [0336] note that the parameters that characterize the result of the reduction can be
    [0337] vary by controlling the composition of the crystalline lattice of the material to be reduced. He
    [0338] doping allows modifying the reducibility of the material, but also its conductivity
    [0339] ionic, which is important since the mobility of the oxygen ion within the network
    [0340] Crystalline plays a role in the reduction process.
    [0341]
    [0342] Table 3A: Effect of doping of the cerium oxide based material, on the increase in the electrical conductivity of said materials, firing temperature and the amount of O 2 released after reduction by microwave application.
    [0343]
    [0344]
    [0345]
    [0346]
    [0347] Similarly, Table 3B shows a summary of the key parameters
    [0348] (firing temperature, amount of O 2 gas released and sharp increase in
    [0349] electrical conductivity) in the reduction of the different materials, based on oxide of
    [0350] Zirconium (Zr 0.86 Y 0.12 O 2 -x, Zr 0.94 Y 0.06 O 2 -xy Zr 0.86 Sc 0.12 O 2 -x), by microwave when a gas stream is passed through the material.
    [0351]
    [0352] Table 3B: Effect of doping of the material based on zirconium oxide, on the increase of the electrical conductivity of said materials, firing temperature and the amount of O 2 released after its reduction by microwave application
    [0353]
    [0354]
    [0355] Example 5
    [0356]
    [0357] Table 4 shows the increase in conductivity, the amount of O 2 released and the firing temperature during the reduction, by applying microwaves of different materials with different composition and crystalline structure. The sample Si 0.4 Al 0.3 Ti 0.1 Fe 0.2 Ox is representative of a typical moon rock. The process was carried out according to example 4. It is observed that it is possible to carry out the reduction in different materials. Specifically, the reduction of the following cations is observed: Ti + 4, Gd + 3, Nb + 5, W + 6, Fe + 3 / Fe + 4, which allows to adjust properties of the microwave reduction process and, therefore, the use of this method in different applications. Figure 13A shows for the CaTio material. 8 Ugly. 2 O 3 -s with perovskite crystalline structure the evolution of the temperature when microwave radiation is applied under a constant flow of dry N 2 (with flow of 100 mL / min under normal conditions) and the measurement of the masses corresponding to the gaseous oxygen released (m = 31.91 and m = 16.03) as a function of time. Figure 13B shows the temporal evolution of the electrical conductivity and the measurement of the mass corresponding to the gaseous oxygen released (m = 31.91) as a function of time.
    [0358] Table 4: Increase of the electrical conductivity of these materials, firing temperature and the amount of O 2 released after reduction by applying microwaves of different materials.
    [0359]
    [0360]
    [0361]
    [0362]
    [0363] Example 6
    [0364]
    [0365] Figure 14 describes the physical-chemical characterization of materials reduced by microwave radiation. Figure 13A shows in the X-ray diffraction diagrams for the CGO sample (Example 1) without reducing and after microwave reduction. A shift of the diffraction peaks to the right is observed for the microwave treated sample, which confirms that the material has been reduced. This increase in the size of the crystalline network parameter is characteristic of the partial reduction of the cation Ce + 4 to Ce + 3.
    [0366]
    [0367] Figure 14B shows the XPS diagrams (photo-electronic X-ray spectroscopy) that allows characterizing the oxidation state of different chemical elements in the most superficial atomic layers of the materials. In this case, as in the Figure 14A, the measurements for the original untreated and microwave treated CGO sample are shown. In general, the reduction of the cation Ce + 4 to Ce + 3 is observed while in this case the reduction of the cation Gd + 3 for this material is not appreciated, given the greater reducibility of the Ce + 4 cation.
    [0368]
    [0369] Example 7
    [0370]
    [0371] This example describes how hydrogen can be generated by reacting the reduced CGO material (by microwave radiation) with water vapor. The process was carried out in an assembly as described in example 1 and passing a stream of Ar (with flow of 100 ml / min under normal conditions) humid (3% vol). The process consisted of three cycles and each is described as follows: (i) microwave radiation is applied so that the temperature rises until the firing temperature is reached and the CGO material is reduced, releasing gaseous O 2 that is dragged by the wet Ar stream, (ii) the microwave radiation is kept on and the temperature is maintained for a few minutes, then (iii) the microwave radiation is stopped and the CGO material is oxidized by extracting the atom from Water oxygen (steam) from the gas stream, which results in the production of H 2 gas, and (iv) finally, the material is allowed to cool to room temperature. Figure 15A shows the temporal evolution of the temperature and the measured signal corresponding to the mass corresponding to oxygen (m = 32) as a function of the time of the experiment. In each cycle, the release of O 2 is observed when the temperature rises under microwave radiation, so that the material is reduced and subsequently maintained for a few minutes at the maximum temperature reached until the microwave radiation ceases and It cools to room temperature. Figure 15B shows the temporal evolution of the temperature and the measurement of the mass corresponding to H 2 (m = 2) as a function of time. In each cycle, the release of H 2 is observed when microwave radiation ceases and the temperature drops, so that the water vapor of the gas stream is reduced to form H 2 and the CGO material is re-oxidized. This figure thus demonstrates a reproducible and cyclable method for H 2 production in accordance with the present invention.
    [0372] Example 8
    [0373]
    [0374] This example describes how CO 2 can be reduced to form CO by reacting the reduced CGO material (by microwave radiation) with CO 2 from a gas stream. The process was carried out in an assembly as described in example 1 and passing a dry gas stream (with flow of 100 ml / min under normal conditions) composed of CO 2 (25% vol.) Diluted in Ar and totally free of N 2 . Similarly to the process described in Example 7, the process consisted of three cycles and each is described as follows: (i) microwave radiation is applied so that the temperature rises until the firing temperature is reached and the CGO material is reduced, releasing O 2 gas that is carried by the gas stream, (ii) the microwave radiation is kept on and the temperature is maintained for a few minutes, then (iii) the microwave radiation and the material ceases CGO is oxidized by extracting an oxygen atom of the CO 2 from the gas stream, which results in the production of CO gas, and (iv) finally, allowed to cool to room temperature the material. Figure 16A shows the temporal evolution of the temperature and the measured signal corresponding to the masses corresponding to O 2 (m = 32) as a function of the time of the experiment. In each cycle, the release of O 2 is observed when the temperature rises under microwave radiation, so that the material is reduced and subsequently maintained for a few minutes at the maximum temperature reached until the microwave radiation ceases and It cools to room temperature. Figure 16B shows the temporal evolution of the temperature and the mass measurement (m = 28) directly related to the presence of CO. In each cycle, the release of CO in two steps (a) is observed when the reduction of the CGO material has taken place (all the O 2 gas has been evacuated) and the temperature begins to stabilize, which implies that the control system Microwave reduces the power of applied radiation and increases its ability to re-oxidize, and (b) when microwave radiation ceases completely and the temperature drops. In both stages the CO 2 of the gas stream is reduced to form CO while the CGO material is re-oxidized. This figure therefore demonstrates a reproducible and cyclable method for CO 2 reduction and CO production according to the present invention.
    权利要求:
    Claims (29)
    [1]
    1. Procedure for the direct reduction of a material, which includes performing the following operations:
    - apply microwave radiation to the material arranged in a microwave applicator cavity,
    - heat the material to at least exceed a firing temperature in the material
    - separation of the generated oxidation fluid products, from the reduced material,
    such that the procedure is carried out without chemical reducing agents,
    and where the firing temperature is a temperature at which the electrical conductivity of the material is sharply increased.
    [2]
    2. Method according to claim 1, characterized in that the procedure is carried out without the use of electrical contacts.
    [3]
    3. Method according to claim 1 or 2, characterized in that it is carried out in a container that has the ability to evacuate fluids.
    [4]
    Method according to one of the preceding claims, characterized in that the application of microwave radiation produces a temperature increase of between 50 200 ° C, and preferably between 50 and 100 ° C, above the firing temperature.
    [5]
    5. Method according to claim 3, characterized in that the electrical conductivity of the material is increased by at least 4% by 4 ° C of temperature increase with respect to the conductivity of the material without reducing.
    [6]
    6. Method according to any one of claims 1 to 5, wherein the evacuated oxidation product is selected from O 2 , O 3 , Ch, F 2 , Br 2 , CO 2 , SO 3 and mixtures thereof.
    [7]
    Method according to any one of claims 1 to 6, in which the material that is reduced is in a solid state, in a molten state, suspended or dissolved in a liquid.
    2
    [8]
    8. The method according to claim 7, wherein the liquid is water or a hydrocarbon capable of being in a liquid state under the conditions in which the process is performed.
    [9]
    9. The method according to claim 1, wherein the separation of the generated oxidation fluid products from the reduced material is carried out by one of the following means or combinations thereof:
    - the application of vacuum,
    - the use of a drag fluid,
    - use of a reactive fluid that consumes it or
    - use of a selective separator of the generated oxidation product
    [10]
    10. A method according to any one of the preceding claims, further comprising an in-situ measurement step of the conductivity of the material to be reduced by applying microwave radiation from a second source and an associated receiver without inferences. mutual.
    [11]
    11. Method according to claim 10, wherein the in-situ measurement of the firing temperature of the material is carried out through measurements of conductivity of the material to be reduced and the temperature of the material.
    [12]
    12. A method according to any one of the preceding claims wherein the material is a solid material whose composition comprises at least one element selected from Ti, Fe, Co, Zr, Cr, Nb, Ta, W, Mo, rare earths and U.
    [13]
    13. Method according to any one of the preceding claims comprising the following steps:
    - place the material in a container capable of evacuating fluids, and inert to MW radiation,
    - insert the container through a hole located in a wall of the applicator cavity in a zone of uniform electric field and as intense as possible for a uniform and efficient heating
    - identify the “firing temperature” for that material,
    - apply microwave radiation until the material is reduced, and
    - carry out while the radiation is applied a continuous adjustment of the power applied to the irradiation, and
    - -separate the oxidation fluid products generated, from the reduced material and such that the process is carried out without reducing chemical agents.
    [14]
    14. Equipment for carrying out the procedure defined in one of the preceding claims, comprising:
    - at least one source of microwave radiation (1),
    - a microwave applicator cavity (2),
    - a container (3) in which the material (4) is deposited, which is to be reduced.
    [15]
    15. Equipment according to the preceding claim, further comprising:
    - at least one temperature sensor (5) to measure the temperature of the material during microwave application (6)
    - at least one means for the evacuation of fluids originated during the reduction procedure (7)
    [16]
    16. Equipment according to claim 14 or 15, wherein the source of microwave radiation (1) for irradiation is based on a magnetron or a microwave generator based on a solid state amplifier.
    [17]
    17. Equipment according to any one of claims 14 to 16 wherein the microwave radiation source (1) has means for operating at frequencies between 300 MHz and 300 GHz.
    [18]
    18. Equipment according to any one of claims 14 to 17 comprising a power isolator (9) for protecting the source of microwave radiation (1).
    [19]
    19. Equipment according to any one of claims 14 to 18, wherein the applicator cavity (2) is a microwave resonator.
    [20]
    20. Equipment according to any one of claims 14 to 19, wherein the microwave resonator has a cylindrical, polyhedral or spherical prismatic shape.
    4
    [21]
    21. Equipment according to any one of claims 14 to 20, wherein the microwave radiation (6) is introduced into the applicator cavity (2) through a waveguide, or through an coupling (10) based on a electric probe or magnetic probe.
    [22]
    22. Equipment according to any one of claims 14 to 21, comprising an access hole (13) in the side wall that allows to measure the temperature of the surface of the material located inside.
    [23]
    23. Equipment according to any one of claims 14 to 22, comprising a second source of microwave radiation for in-situ conductivity measurements and without interference with the first source of radiation (1).
    [24]
    24. Equipment according to any one of claims 14 to 23, wherein the applicator cavity (2) has at least one non-radiant hole (11) located in the upper wall and a second non-radiant hole (11) located in the wall lower, which allow the passage of substances.
    [25]
    25. Equipment according to claim 214, wherein the non-radiant holes located in the upper and lower wall (11) allow the introduction and evacuation of gases.
    [26]
    26. Equipment according to any one of claims 14 to 25, further comprising means for evacuating fluids originated during the reduction process.
    [27]
    27. A reduced material obtained by the process defined in one of claims 1 to 13.
    [28]
    28. Use of the method defined in one of claims 1 to 13, or of the reduced material defined in claim 27, in industrial, agricultural or medicinal processes.
    [29]
    29. Use according to claim 28 wherein the reduced material is used as a selective absorbent to treat a gas stream.
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    同族专利:
    公开号 | 公开日
    CA3131091A1|2020-09-03|
    KR20220017883A|2022-02-14|
    ES2726028B2|2020-06-11|
    ES2726028A8|2020-03-16|
    WO2020174118A1|2020-09-03|
    EP3932538A1|2022-01-05|
    US20220016595A1|2022-01-20|
    AU2020229450A1|2021-09-16|
    引用文献:
    公开号 | 申请日 | 公开日 | 申请人 | 专利标题
    US5507927A|1989-09-07|1996-04-16|Emery Microwave Management Inc.|Method and apparatus for the controlled reduction of organic material|
    US20040100280A1|2002-11-27|2004-05-27|Tohoku Techno Arch Co., Ltd.|Noncontact measuring system for electrical conductivity|
    CN109022760A|2018-09-14|2018-12-18|东北大学|A kind of microwave-fluosolids roasting method for strengthening the sorting of Refractory iron ore stone|
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    KR1020217031082A| KR20220017883A|2019-02-28|2020-02-28|Direct reduction of materials using microwave radiation|
    EP20763309.0A| EP3932538A1|2019-02-28|2020-02-28|Method for directly reducing a material by means of microwave radiation|
    PCT/ES2020/070146| WO2020174118A1|2019-02-28|2020-02-28|Method for directly reducing a material by means of microwave radiation|
    CA3131091A| CA3131091A1|2019-02-28|2020-02-28|Method for directly reducing a material by means of microwave radiation|
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    US17/458,213| US20220016595A1|2019-02-28|2021-08-26|Method For Directly Reducing A Material By Means Of Microwave Radiation|
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