Process for Recovering Deuterium Using an Oxidation Reaction of Deuterium

Abstract

The present invention relates to a process for recovering deuterium (D₂), and more specifically, to a process for recovering deuterium discharged or remaining from industrial processes by converting it into heavy water (D₂O) through an oxidation reaction. The deuterium recovery process using the oxidation reaction of deuterium according to the present invention comprises: a step of supplying a gas containing deuterium (D₂) that is discharged or remains in an industrial process; a step of converting the deuterium into heavy water (D₂O) by oxidizing the deuterium; and a step of recovering the heavy water. By converting deuterium into heavy water through an oxidation reaction and recovering it, flammable and explosive deuterium can be recovered in a stable liquid form, which has the effect of improving process safety. In addition, by optimizing the oxidation reaction conditions of deuterium, the conversion efficiency and recovery rate of deuterium can be improved, thereby minimizing the loss of deuterium resources.

Description

Technology Field

[0001] The present invention relates to a process for recovering deuterium (D₂), and more specifically, to a process for recovering deuterium discharged or remaining in industrial processes, such as semiconductors, by converting it into heavy water (D₂O) through an oxidation reaction. Background Technology

[0003] Generally, deuterium (D₂) is a stable isotope of hydrogen that has a larger mass and higher binding energy than ordinary hydrogen, resulting in relatively lower reactivity. Due to these characteristics, deuterium is used as an important process gas or raw material in various industrial and research fields, such as improving the reliability of semiconductor devices, passivation in display processes, nuclear fusion and nuclear research, precision analysis, and pharmaceutical and bio research. In particular, in semiconductor and display manufacturing processes, deuterium is useful for stabilizing gate oxides or interfacial defects, leading to a continuous increase in the demand for high-purity deuterium gas.

[0004] However, in these industrial processes, a significant amount of deuterium used is often released unreacted after the reaction or mixed with inert gases such as nitrogen (N₂). Conventionally, methods generally used to release these deuterium-containing exhaust gases into the atmosphere without a separate recovery process or to simply treat them using scrubbers have been employed. Such methods not only result in the loss of deuterium, a high-value resource, but also present limitations in terms of safety, considering that deuterium is a flammable gas with an explosive range.

[0005] While direct compression and storage of deuterium gas can be considered as an existing technology for deuterium recovery, deuterium possesses low ignition energy and a wide explosive range similar to ordinary hydrogen, posing a constant risk of explosion and leakage during high-pressure compression and storage. Furthermore, direct recovery of deuterium gas requires large-scale facility investments, such as high-pressure compressors, storage containers, and explosion-proof equipment, leading to significant increases in equipment and operating costs. In particular, the application of such high-pressure gas recovery systems is often practically difficult in environments with severe space constraints, such as semiconductor and display production sites.

[0006] Meanwhile, while a method of converting deuterium into liquid-phase heavy water (D₂O) for recovery could be proposed as an alternative, conventional technology for stably controlling and continuously applying deuterium oxidation reactions at the process level has not been sufficiently established. Since general hydrogen oxidation reactions involve high reaction rates and exothermic reactions, there is a risk of explosion or localized overheating if reaction conditions are not controlled properly. In particular, although deuterium has reaction characteristics similar to hydrogen, there are differences in reaction rate and kinetic behavior, so there are technical limitations to applying existing hydrogen oxidation processes as is.

[0007] Furthermore, deuterium gas emitted from industrial processes is mostly not a single component of pure deuterium, but rather a mixed gas containing nitrogen, oxygen (O2), hydrogen (H₂), deuteride (HD), and trace amounts of moisture or organic impurities. To selectively recover only deuterium from such mixed gases, or to recover deuterium by converting it into a stable form, process technology is required that comprehensively considers reaction conditions, reactor structure, thermal management, and safety design. However, conventional technologies have not sufficiently proposed deuterium recovery processes that satisfy these complex requirements.

[0008] Furthermore, deuterium recovery processes must not stop at merely capturing deuterium but must also consider economic feasibility and the possibility of continuous operation to enable the reuse of the recovered deuterium or heavy water in subsequent processes. However, existing deuterium processing technologies have often remained at the level of laboratory-scale experimental approaches or have been limited to application in specialized environments such as large-scale nuclear facilities, posing limitations to their direct application in civilian industrial processes like the semiconductor and display industries.

[0009] As such, conventional deuterium treatment and recovery technologies have various limitations in terms of safety, economic feasibility, recovery efficiency, and industrial applicability. In particular, there is a continuous demand for practical process technologies capable of stably and efficiently recovering deuterium emitted from industrial processes. Therefore, there is a need to develop a new deuterium recovery process that can effectively recover deuterium generated in industrial sites while minimizing its flammability and handling risks. Prior art literature

[0011] Japanese Registered Patent No. 7551455 (Registration Date: Sep. 06, 2024) Korean Published Patent No. 10-2024-0033009 (Publication Date: March 12, 2024) The problem to be solved

[0012] The present invention has been devised to solve the problems of the prior art described above, and aims to provide a deuterium recovery process capable of safely and efficiently recovering deuterium discharged or remaining in industrial processes. Another objective of the present invention is to improve handling safety by recovering deuterium, which poses flammability and explosion risks, by converting it into a stable liquid form through an oxidation reaction, rather than directly compressing and storing it.

[0013] The present invention aims to provide a deuterium recovery process that improves the conversion efficiency and recovery rate of deuterium by optimizing the oxidation reaction conditions of deuterium, and enables the recovery of deuterium discharged in the form of mixed gas without a separate, complex separation process. Furthermore, during the process of recovering deuterium in the form of heavy water, only deuterium among the main components of the mixed gas is selectively oxidized to recover heavy water, thereby allowing for the expectation of a purification effect in which components such as nitrogen are naturally separated.

[0014] Furthermore, the present invention aims to provide an economical deuterium recovery process capable of recovering and reusing deuterium through a simplified process configuration applicable to industrial sites.

[0015] The technical problems that the present invention aims to solve are not limited to those mentioned above, and other unmentioned technical problems will be clearly understood by those skilled in the art from the description below. means of solving the problem

[0017] The present invention relates to a process for recovering deuterium emitted or remaining in industrial processes by converting it into heavy water (D₂O) through an oxidation reaction.

[0018] To achieve the technical objectives described above, the deuterium recovery process using the oxidation reaction of deuterium according to the present invention comprises: a step of supplying a gas containing deuterium (D₂) that is discharged or remains in an industrial process; a step of converting the deuterium into heavy water (D₂O) by oxidizing the deuterium; and a step of recovering the heavy water.

[0019] Additionally, the oxidation reaction may include contacting deuterium using oxygen (O2) or a gas containing oxygen and a metal oxidizing agent comprising at least one of copper oxide, iron oxide, manganese oxide, and nickel oxide as an oxidizing agent, and performing the reaction under controlled conditions of reaction temperature, reaction pressure, and gas flow rate.

[0020] According to a preferred embodiment of the present invention, the oxidation reaction is carried out in the presence of a metal catalyst comprising one or more selected from platinum (Pt), palladium (Pd), ruthenium (Ru), iridium (Ir), nickel (Ni), cobalt (Co), or alloys thereof, and the metal catalyst may be provided in either a bulk metal form or a form supported on a support, and may contain 0.01 to 50 weight percent of a metal component based on the total weight of the catalyst.

[0021] In addition, according to a preferred embodiment of the present invention, the metal catalyst is supported on an inorganic oxide or ceramic support capable of maintaining structural stability in a high-temperature oxidizing or reducing atmosphere, and the support comprises one or more selected from alumina, silica, silica-alumina, zeolite, zirconia (ZrO₂), titania (TiO₂), ceria (CeO₂), magnesia (MgO), or a mixture thereof, and the amount of the metal catalyst supported may be 0.1 to 50 weight% based on the support.

[0022] In addition, according to a preferred embodiment of the present invention, the oxidation reaction may be carried out in a reactor designed to have a temperature range of 800°C or higher and a residence time of the reaction gas passing through the catalyst layer of 0.01 seconds or more, and the reaction rate may be controlled so that the deuterium is oxidized and converted for longer than the said residence time.

[0023] Additionally, the deuterium is supplied in the form of a mixed gas including nitrogen, hydrogen (H₂), deuteride hydrogen (HD), inert gas, or process residual gas, wherein the content of deuterium (D₂) in the mixed gas is 0.01 to 100 mol% relative to the total gas, and the oxidation reaction may be performed under conditions in which the oxygen is supplied in excess of the theoretical amount, based on a theoretical stoichiometric amount of 1 mol of oxygen (O₂) per 2 mol of deuterium (D₂).

[0024] In addition, the recovery process may include converting deuterium in a combustible gaseous state into liquid heavy water (D₂O) through the oxidation reaction, and recovering the heavy water through a condensation or storage process.

[0025] Additionally, the method may further include a heavy water reuse step in which the heavy water recovered in the above-mentioned heavy water recovery step is reused in a deuterium production process or a heavy water concentration process. Effects of the invention

[0027] According to the present invention, by converting deuterium into heavy water through an oxidation reaction and recovering it, deuterium, which is flammable and poses an explosion risk, can be recovered in a stable liquid form, thereby improving the safety of the process.

[0028] In addition, by optimizing the oxidation reaction conditions of deuterium, the conversion efficiency and recovery rate of deuterium can be improved, thereby minimizing the loss of deuterium resources.

[0029] The present invention can recover deuterium in the form of mixed gases emitted from industrial processes without a separate complex separation process, and can reduce equipment investment and operating costs by having a simpler facility configuration compared to existing methods of directly compressing and storing deuterium.

[0030] Furthermore, the present invention allows the recovered heavy water to be reused in subsequent deuterium production processes or other application processes, thereby increasing the resource circulation and economic value of deuterium. Brief explanation of the drawing

[0032] FIG. 1 is a schematic diagram showing a deuterium recovery process according to an embodiment of the present invention. FIG. 2 is a conceptual diagram of a deuterium recovery process according to an embodiment of the present invention. Specific details for implementing the invention

[0033] Hereinafter, a deuterium recovery process using the oxidation reaction of deuterium according to the present invention will be described in more detail with specific examples. However, the embodiments introduced below are provided as examples to ensure that the concept of the present invention is sufficiently conveyed to those skilled in the art.

[0034] Accordingly, the present invention is not limited to the embodiments presented below and may be embodied in other forms, and the embodiments presented below are described merely to clarify the concept of the present invention and are not limited thereto.

[0035] Unless otherwise defined, technical and scientific terms used herein have the meanings commonly understood by those skilled in the art to which this invention pertains, and are defined in consideration of their functions in the present invention; such definitions may vary depending on the intent or convention of the user or operator. Therefore, the definitions of these terms should be based on the content throughout this specification, and descriptions of known functions and configurations that could unnecessarily obscure the essence of the present invention are omitted in the following description.

[0036] Additionally, the singular form used in the specification and attached claims may be intended to include the plural form unless specifically indicated otherwise in the context.

[0037] The present invention will be described in detail below.

[0038] The deuterium recovery process using the oxidation reaction of deuterium according to the present invention comprises: a step of supplying a gas containing deuterium (D₂) that is discharged or remains in an industrial process; a step of converting the deuterium into heavy water (D₂O) by oxidizing the deuterium; and a step of recovering the heavy water.

[0039] The present invention is primarily characterized by simultaneously improving process safety and recovery efficiency by converting deuterium into a relatively stable liquid form of heavy water using an oxidation reaction and recovering it, instead of directly compressing and storing deuterium in a combustible gaseous state.

[0040] In the step of supplying a gas containing deuterium (D₂) emitted or remaining in the above industrial process; the gas containing deuterium (D₂) is a gas emitted or remaining in the industrial process, and may contain deuterium as a single component, or may be in the form of a mixed gas containing inert gases such as nitrogen (N₂), hydrogen (H₂), deuteride hydrogen (HD), argon (Ar), or process residual gases (e.g., process exhaust residual components).

[0041] Specifically, gas containing deuterium can be captured from exhaust gas lines discharged after the use of deuterium, which is used in various fields such as semiconductor or display manufacturing processes as well as chemistry, pharmaceuticals, fine chemicals, nuclear power, nuclear fusion, and optical fibers, and supplied to this process; the composition and flow rate of the supplied gas can vary depending on the discharge process conditions.

[0042] In one embodiment, the content of deuterium (D₂) in the mixed gas may be 0.01 to 100 mol% relative to the total gas. That is, it is widely applicable from low-concentration exhaust gas conditions in actual industrial sites to high concentrations or deuterium streams that are virtually close to a single component, depending on process conditions or the configuration of the recovery line.

[0043] The above gas supply may be provided through piping from a gas storage container, discharge line, or recovery line, and the supply flow rate may be controlled to ensure the recovery efficiency of deuterium and the stability of the oxidation reaction. Preferably, the supply gas may be introduced into the oxidation reaction stage after reducing particulate contaminants or the risk of backflow through a filter, trap, or valve, but is not limited thereto.

[0044] The step of converting the above deuterium into heavy water (D₂O) by oxidizing it may use oxygen (O₂) or a gas containing oxygen, and a metal oxidizing agent comprising at least one of copper oxide, iron oxide, manganese oxide, and nickel oxide as the oxidizing agent. Specifically, pure oxygen, air, an inert gas mixed with oxygen, or a mixed gas with controlled oxygen concentration may be used as the oxidizing agent.

[0045] The above oxidation reaction may be carried out in the presence of a catalyst, and as the catalyst, a metal catalyst comprising one or more selected from platinum (Pt), palladium (Pd), ruthenium (Ru), iridium (Ir), nickel (Ni), cobalt (Co), or alloys thereof may be used. The metal catalyst may be provided in either a bulk metal form or a form supported on a support, and may be configured to be filled inside a reactor in the form of a catalyst layer (catalyst bed) so that the oxidation reaction proceeds as the reaction gas passes through the catalyst layer.

[0046] The above metal catalyst may contain 0.01 to 50 weight percent of a metal component based on the total weight of the catalyst. If the content of the metal component is excessively low, the number of catalyst active sites is insufficient, so the oxidation reaction of deuterium may not proceed sufficiently, or excessive reaction conditions may be required to secure the same conversion rate. Conversely, if the content of the metal component is excessively high, problems such as increased catalyst manufacturing costs, sintering of metal particles, or reduced thermal stability may occur; therefore, in the present invention, the content may be appropriately selected within the above range depending on the process conditions and the catalyst form (bulk / support).

[0047] The metal catalyst may be a single metal catalyst or an alloy catalyst composed of multiple metals. When using an alloy catalyst, the adsorption and activation characteristics of deuterium can be controlled by changes in the electronic structure between the metals, thereby improving the conversion rate of the oxidation reaction and the catalyst lifespan. The form and composition of such a catalyst may be varied within the scope of the technical concept of the present invention.

[0048] Preferably, the metal catalyst may be an alloy catalyst comprising platinum and palladium, and the molar ratio of platinum to palladium may be in the range of 4:1 to 1:4. More preferably, the alloy catalyst may be a core-shell structured alloy with different component ratios on the surface and inside, and the surface composition may be controlled so that a specific metal component is relatively abundantly distributed on the surface of the alloy catalyst particles. By controlling the surface composition, the adsorption and activation of deuterium are promoted, so that the oxidation reaction can proceed stably even under short residence time conditions.

[0049] When the above metal catalyst is in a supported form, the metal catalyst may be supported on an inorganic oxide or ceramic support capable of maintaining structural stability in a high-temperature oxidizing or reducing atmosphere. The support may be one or more selected from alumina (Al₂O₃), silica (SiO₂), silica-alumina, zeolite, zirconia (ZrO₂), titania (TiO₂), ceria (CeO₂), magnesia (MgO), or mixtures thereof.

[0050] The composite support above may be a silica-alumina composite support comprising silica (SiO₂) and alumina (Al₂O₃).

[0051] The above silica provides a high specific surface area and a developed pore structure to improve the dispersibility of metal catalysts, and the above alumina can provide mechanical strength and thermal stability under high-temperature oxidation reaction conditions.

[0052] Specifically, the weight ratio of the silica and alumina may be in the range of 90:10 to 10:90, and preferably in the range of 70:30 to 30:70.

[0053] In addition, the composite support may be an alumina-zirconia composite support comprising alumina (Al₂O₃) and zirconia (ZrO₂).

[0054] The above zirconia can play a role in suppressing the sintering of catalyst particles through structural stability under high-temperature conditions and enhanced interaction with metal catalysts.

[0055] Specifically, the weight ratio of alumina to zirconia may be in the range of 95:5 to 50:50.

[0056] In addition, the above composite support may be a ternary composite support comprising silica (SiO₂), alumina (Al₂O₃), and ceria (CeO₂).

[0057] The above ceria provides oxygen storage capacity in an oxidation-reduction environment, which can mitigate fluctuations in local oxygen concentration during oxidation reactions and improve the stability of deuterium oxidation reactions.

[0058] Specifically, the content of the ceria may be 1 to 20 weight percent based on the total weight of the composite carrier.

[0059] The loading amount of the metal catalyst can be set to a range of 0.1 to 50 weight percent based on the support. If the loading amount is excessively low, the density of catalytic active sites formed on the surface of the support may decrease, which may result in insufficient progress of the deuterium oxidation reaction or a decrease in the reaction rate; if the loading amount is excessively high, aggregation between metal catalyst particles may occur, leading to a decrease in the effective active area or a decrease in the thermal stability of the catalyst during the reaction. Within the above loading range, a balance between the dispersibility, reaction activity, and thermal stability of the metal catalyst can be effectively secured.

[0060] The shape of the above-mentioned support can be implemented in various forms, such as powder, pellets, beads, or honeycomb structures, and such morphological variations can be selected depending on the reactor structure and gas flow characteristics. In addition, the support may undergo an acid treatment process before the metal catalyst is supported, and after the acid treatment process, the density of active sites on the surface of the support and the dispersibility of the metal catalyst may be improved.

[0061] Specifically, the support may undergo a pretreatment process, and the pretreatment process may be a complex pretreatment process that sequentially includes an acid treatment process and a heat treatment process.

[0062] Specifically, by heat-treating a support material that has undergone washing and drying after an acid treatment process at a temperature of 400 to 800°C for 1 to 5 hours, it is possible to simultaneously secure an increase in the density of active sites on the surface of the support material and dispersion stability after metal catalyst support.

[0063] In addition, the loading of the metal catalyst may be performed by a stepwise loading method in which a specific metal is loaded first and then another metal is loaded, and by controlling the loading order to control the catalyst surface composition, the effect of promoting the initial adsorption reaction of deuterium can be obtained.

[0064] The above stepwise loading can be performed by first loading a support using a metal precursor solution containing a first metal component, then drying and heat-treating the support to immobilize the first metal component, and then performing a second loading process using a metal precursor solution containing a second metal component.

[0065] As the metal precursors mentioned above, for palladium (Pd), PdCl₂, Pd(NO₃)₂, or Pd(acac)₂ may be used, and for platinum (Pt), H₂PtCl₆, Pt(NH₃)₄Cl₂, or Pt(acac)₂ may be used, but are not limited thereto.

[0066] In one embodiment, the concentration of the metal precursor solution may be in the range of 0.001 to 1.0 M, and the impregnation method may include incipient wetness impregnation or immersion impregnation.

[0067] The above soaking time may be in the range of 0.5 to 12 hours, and preferably 1 to 4 hours.

[0068] The drying conditions after the first loading may be 1 to 12 hours at 80 to 150°C, and subsequent heat treatment (calcination) for immobilization may be performed at 300 to 700°C for 0.5 to 5 hours. The heat treatment atmosphere may be air, nitrogen, or an inert gas.

[0069] In addition, the oxidation reaction can be performed under controlled conditions of reaction temperature, reaction pressure, and reaction gas flow rate. The reactor may be equipped with a heater, a temperature sensor, a pressure sensor, a flow controller (MFC), etc., thereby enabling the oxidation reaction to be performed stably.

[0070] In one embodiment, the oxidation reaction may be carried out in a temperature range of 800°C or higher. High temperature conditions promote the oxidation reaction of deuterium and can contribute to securing the oxidative conversion of deuterium even with a short contact time passing through the catalyst layer. The reaction pressure can be appropriately set according to the reactor and piping design, and the control of the reaction pressure affects the residence time of the reaction gas, the contact efficiency with the catalyst, and the reaction rate, thereby playing a role in stably securing the conversion efficiency of deuterium.

[0071] The flow rates of the deuterium gas and oxygen-containing gas used in the above oxidation reaction can be individually controlled through a Mass Flow Controller (MFC). Specifically, by independently controlling the flow rates of the deuterium gas and the oxygen gas, the stoichiometric ratio inside the reactor can be adjusted, thereby minimizing safety issues caused by residual deuterium or excess oxygen.

[0072] In one embodiment, the oxygen supply amount may be set based on a theoretical stoichiometric amount of 1 mole of oxygen (O₂) per 2 moles of deuterium (D₂), and the oxidation reaction may be carried out under conditions where oxygen is supplied in excess of the theoretical amount. Such excess oxygen supply can contribute to stably securing the oxidative conversion of deuterium even if there are variations in the composition of the supply gas or local reaction non-uniformity within the reactor.

[0073] In one embodiment, the amount of oxygen (O₂) supplied may be supplied in excess of at least 1.01 times the theoretical stoichiometric amount of 1 mole of oxygen (O₂) per 2 moles of deuterium (D₂).

[0074] In addition, in another embodiment, the oxygen may be supplied in an excess of 1.05 to 5 times the theoretical stoichiometric amount, and in another embodiment, in an excess of 1.1 to 3 times.

[0075] In addition, the oxidation reaction can be carried out in a reactor designed so that the residence time of the reaction gas passing through the catalyst layer is 0.01 seconds or longer. Specifically, the residence time can be set to the above conditions by controlling the length, cross-sectional area, and charge amount of the catalyst layer inside the reactor, as well as the flow rate of the reaction gas. At this time, the reaction rate can be controlled so that deuterium is oxidized and converted for longer than the above residence time, and if necessary, the reaction can be carried out while preventing local overheating through a heat exchange structure or a multi-stage reaction structure.

[0076] In one embodiment, when the reaction temperature is 800°C or higher, the oxidative conversion of deuterium can be substantially completed even under very short conditions in which the residence time of the reaction gas passing through the catalyst layer is in the range of 0.01 to 0.5 seconds.

[0077] In this way, the combination of high temperature conditions and a short residence time enables the miniaturization of the reactor and continuous process operation, and effectively reduces safety risks associated with the retention of deuterium in the reactor.

[0078] The reactor may include a gas distribution structure for uniformly distributing the flow of reaction gas, a heat dispersion structure or a heat exchange structure for preventing local overheating of the catalyst layer, and through the heat exchange structure, the reaction can proceed uniformly throughout the reactor without local concentration or runaway even under short residence time conditions.

[0079] The step of recovering the heavy water above; may result in the heavy water (D₂O) generated by the oxidation reaction being discharged in a gaseous state (in the form of steam) or discharged at the reactor outlet in a gas-liquid mixed form.

[0080] In order to recover the generated heavy water, the present invention allows for the recovery of the heavy water in a liquid state by cooling the product gas to condense it, adsorbing it onto an adsorbent, or combining condensation and adsorption technologies (adsorption using a molecular sieve may be added later). Cooling can be achieved through devices such as condensers, heat exchangers, and cooling coils, and the cooling temperature can be controlled according to the condensation efficiency and recovery rate.

[0081] The above-mentioned condensed heavy water can be collected in a recovery tank or storage container, and, if necessary, non-condensable gases (e.g., N₂, residual O₂, etc.) can be discharged through a vent or scrubber. Additionally, the recovered heavy water can be reused in subsequent processes, for example, as a raw material for a deuterium production process or as an input raw material for a heavy water concentration process.

[0082] The process of the present invention is not limited to the embodiments described above, and various modifications are possible regarding the supply gas composition, catalyst type and form (bulk / supported), reactor structure, oxidant supply method, cooling and condensation methods, etc. For example, the oxidation reaction may be performed in a single reactor, or by arranging multiple reactors in series or parallel. Furthermore, the oxidation reaction step and the recovery step may be performed as a continuous process, or may be performed in a semi-continuous or batch manner depending on the process conditions.

[0083] The above oxidation reaction may include contacting oxygen or a gas containing oxygen with deuterium, and carrying out the reaction under controlled conditions of reaction temperature, reaction pressure, and gas flow rate. By controlling the reaction conditions, the oxidation reaction of deuterium can be carried out stably, and the occurrence of localized overheating, explosion risk, or incomplete reaction can be effectively suppressed.

[0084] Specifically, in the oxidation reaction step, a gas containing deuterium (D₂) and oxygen (O₂) or a gas containing oxygen are brought into contact inside a reactor, and the oxygen can be supplied in the form of pure oxygen, air, or a mixed gas with a controlled oxygen concentration. The amount of oxygen supplied can be set considering the concentration of deuterium, the reaction rate, and the amount of heat generated inside the reactor, and can be supplied in excess based on the theoretical stoichiometric amount to stably ensure the oxidative conversion of deuterium.

[0085] The above oxidation reaction can be performed under controlled reaction temperatures. Specifically, the reactor may include an electric heater, a gas heater, or a heat transfer medium circulation device, and the amount of heating can be controlled according to the internal temperature of the reactor measured by a temperature sensor. Such temperature control can contribute to preventing catalyst degradation, reactor damage, or excessive heat generation while ensuring that the oxidation reaction of deuterium proceeds sufficiently.

[0086] The above oxidation reaction can be carried out under controlled reaction pressure. Pressure regulating valves or pressure control devices may be provided at the inlet and outlet of the reactor, thereby maintaining the internal pressure of the reactor within a certain range. Since the control of reaction pressure affects the residence time of the reaction gas, the contact efficiency with the catalyst, and the reaction rate, it plays a role in stably securing the conversion efficiency of deuterium.

[0087] In one embodiment of the present invention, a control unit may be included that provides real-time feedback control of oxidation reaction conditions based on data collected from a temperature sensor, a pressure sensor, and a flow rate controller. Through this feedback control, the oxidation reaction can be stably maintained even if fluctuations in process conditions or changes in the supply gas composition occur, and consequently, the recovery efficiency of deuterium and process reliability can be improved.

[0088] In addition, the recovery process may include converting deuterium in a combustible gaseous state into liquid deuterium (D₂O) through the oxidation reaction, and recovering the deuterium through a condensation or storage process. The present invention can simultaneously ensure process safety and ease of handling by recovering deuterium by converting it into a stable liquid form through an oxidation reaction, rather than directly capturing or storing it in a gaseous state.

[0089] In addition, the deuterium recovery process of the present invention may further include a deuterium reuse step in which the deuterium recovered in the step of recovering the deuterium is reused in a deuterium production process or a deuterium concentration process. By recycling the recovered deuterium as a raw material for a subsequent process, rather than merely treating or disposing of the deuterium, the deuterium resource can be utilized in a circular manner.

[0090] Specifically, the condensed and recovered heavy water (D₂O) can be temporarily stored in a storage container and then fed as a raw material for a deuterium production process. The heavy water can be decomposed into deuterium (D₂) and oxygen (O₂) through an electrolysis process, and the deuterium generated from the decomposition can be purified into high-purity deuterium gas and reused in industrial processes. The inclusion of a heavy water reuse step can reduce dependence on external procurement of deuterium and provide the effect of reducing process operating costs.

[0091] The recovered heavy water can be used as an input raw material for a heavy water concentration process. The concentration of the heavy water can be enhanced through a concentration process that combines electrolysis and a catalyst-based isotope substitution reaction, and the concentrated heavy water can be reused in a deuterium recovery or purification process. The deuterium recovery process of the present invention can be organically linked with a subsequent concentration process to form a resource circulation structure.

[0092] The reuse step of the recovered heavy water can be performed in the form of a continuous process or a batch process, and can be appropriately selected depending on the process scale and operating conditions. This reuse step may be performed independently of the deuterium recovery process of the present invention, or it may be configured as a single integrated process line.

[0094] The present invention will be explained in more detail below with reference to examples and comparative examples.

[0095] Embodiments of the present invention are described in detail so that those skilled in the art can easily implement them. However, since the description of the present invention is merely an example for structural or functional explanation, the scope of the rights of the present invention should not be interpreted as being limited by the embodiments described in the text. That is, since the embodiments are subject to various modifications and may take various forms, the scope of the rights of the present invention should be understood to include equivalents capable of realizing the technical concept. Furthermore, the objectives or effects presented in the present invention do not imply that a specific embodiment must include all of them or only such effects; therefore, the scope of the rights of the present invention should not be understood as being limited by them.

[0097] <Example 1> - Evaluation of Deuterium Oxidation Reaction Rate Using Pt / Al₂O₃ Catalyst

[0098] In this example, the characteristics of the oxidation reaction of deuterium were evaluated under high temperature and short residence conditions in the presence of a metal catalyst using a catalyst in which platinum (Pt) was supported on an alumina (Al₂O₃) support. The catalyst used was a supported catalyst in which platinum was supported on an alumina support at 1 wt% based on the total weight of the catalyst. Deuterium (D₂) and oxygen (O₂) were supplied to a reactor to perform the oxidation reaction, and the reaction pressure was maintained at 5 bar. Oxygen was supplied in an excess amount of approximately 1.2 times based on the theoretical stoichiometric amount of 1 mole of oxygen (O₂) per 2 moles of deuterium (D₂). The reaction temperatures were set to 800°C, 850°C, and 900°C, respectively. The minimum residence time required for more than 99% conversion of deuterium to heavy water (D₂O) was measured while varying the residence time of the reaction gas passing through the catalyst layer, and the results are shown in Table 1.

[0099] Reaction temperature (°C) 800 850 900 99% conversion minimum time spent (sec) 1.8 1 0.6

[0101] As a result, it was confirmed that under conditions where the reaction temperature is 800°C or higher, the oxidation reaction of deuterium proceeded almost completely even with a residence time of a few seconds or less, and in particular, at 850°C or higher, the oxidative conversion of deuterium was stably achieved even with a residence time of approximately 1 second. This clearly demonstrates that the high temperature condition of 800°C or higher and the short residence time condition of 0.01 seconds or more specified in the present invention are effective for the deuterium oxidation reaction.

[0102] In the following examples, the same reaction conditions and evaluation methods as in Example 1 were applied unless otherwise noted.

[0104] <Example 2> - Comparison of Deuterium Oxidation Reaction Performance According to Catalyst Structure and Support Composition

[0105] In this embodiment, the same reactor configuration and deuterium oxidation reaction evaluation method as in Example 1 were used, but the performance of the deuterium oxidation reaction was compared and evaluated according to differences in the metal composition of the catalyst, the configuration of the support, the pretreatment of the support, and the metal support method while keeping the reaction conditions constant. Specifically, in all experiments of the Example 2 series, the reaction temperature was set to 850°C and the reaction pressure to 1 bar, and the residence time of the reaction gas passing through the catalyst layer was maintained at 0.2 seconds. In addition, oxygen was supplied in an excess amount of approximately 1.3 times based on the theoretical stoichiometric amount of 1 mole of oxygen (O₂) per 2 moles of deuterium (D₂).

[0106] In the following Examples 2-1 to 2-4, the effects were compared by changing only the catalyst components stepwise while maintaining the above conditions identically.

[0108] <Example 2-1> - Pt / Al₂O₃ supported catalyst

[0109] In this example, the deuterium oxidation reaction was carried out in the same manner as in Example 1, but the reaction temperature was fixed at 850°C, and a catalyst was used in which platinum (Pt) was supported on an alumina support at 1% by weight of the total catalyst. As a result, the deuterium reaction rate was approximately 89%, and the recovery rate of the generated heavy water was confirmed to be approximately 86%.

[0110] <Example 2-2> - Pt-Pd alloy / Al₂O₃ supported catalyst

[0111] This example is performed under the same conditions as Example 2-1 to carry out a deuterium oxidation reaction, differing only in that the catalyst metal was changed to a platinum-palladium (Pt-Pd) alloy. The molar ratio of platinum to palladium was set to approximately 1:1, and the total metal content was maintained at 1 wt% based on the total catalyst. As a result, the deuterium reaction rate was approximately 92% and the deuterium recovery rate was approximately 89%, showing improved performance compared to Example 2-1, which used a single metal catalyst.

[0112] <Example 2-3> - Pt-Pd alloy / silica-alumina composite support + support pretreatment

[0113] This embodiment is different in that it performs a deuterium oxidation reaction under the same conditions as Example 2-2, but changes the support from a single alumina support to a silica-alumina composite support, and additionally performs a support pretreatment process including acid treatment and heat treatment before metal support. As a result, the deuterium reaction rate was confirmed to be approximately 95% and the deuterium recovery rate approximately 91%, which is attributed to the improvement in catalyst dispersibility and high-temperature stability due to the support pretreatment.

[0114] <Example 2-4> - Pt-Pd alloy catalyst with controlled surface composition + stepwise support

[0115] This embodiment performs a deuterium oxidation reaction under the same conditions as Examples 2-3, but differs only in that the metal catalyst loading method is changed to apply a stepwise loading method in which palladium (Pd) is loaded first and then platinum (Pt). As a result, the composition is controlled so that the palladium component is relatively abundantly distributed on the surface of the catalyst particles, and the Pt:Pd molar ratio in the surface part is approximately 1:3, and in the interior part is approximately 3:1. Consequently, the deuterium reaction rate was approximately 97% and the deuterium recovery rate was approximately 93%, showing the best performance among all embodiments.

[0116] <Example 3> Evaluation of Heavy Water Production Amount and Recovery Rate Under Continuous Operation Conditions

[0117] In this embodiment, the same catalyst composition and reaction mechanism as in Example 1 were applied, but the reaction was carried out in a continuous operation manner to evaluate the reproducibility and stability of the process.

[0118] The reaction temperature was set to 900℃ and the reaction pressure to 5 bar, and the deuterium flow rate was 1000 cc / min and the oxygen flow rate was 650 cc / min, which is approximately 1.25 times the theoretical stoichiometric amount. As a result of cooling and condensing the reactor outlet gas, the actual recovery amount was measured to be 0.782 g / min compared to the theoretical heavy water production amount of 0.818 g / min, confirming a heavy water recovery rate of approximately 96%.

[0119] <Comparative Example 1> - Evaluation of Deuterium Oxidation Reaction Rate Under Catalyst-Free Conditions

[0120] This comparative example is performed under the same reaction conditions as Example 1 for the deuterium oxidation reaction, but differs only in that no metal catalyst was used. Specifically, the reaction temperature was set to 850°C, the reaction pressure to 5 bar, and the residence time of the reaction gas to 0.2 seconds, and oxygen was supplied in an excess amount of about 1.2 times the theoretical stoichiometric amount of 1 mole of oxygen (O₂) per 2 moles of deuterium (D₂). However, under conditions without a catalyst, the deuterium oxidation reaction did not proceed sufficiently despite the high temperature and excess oxygen conditions, and the deuterium conversion rate remained at about 40%.

[0121] This clearly demonstrates that the application of the metal catalyst proposed in this invention is an essential technical configuration for substantially completing the deuterium oxidation reaction under high temperature and short residence conditions.

[0123] <Comparative Example 2> - Deuterium oxidation reaction and deuterium recovery characteristics under catalyst-free conditions

[0124] This comparative example was conducted to verify the effect of the absence of a catalyst on the heavy water recovery performance by performing a deuterium oxidation reaction under catalyst-free conditions without using a metal catalyst, identical to Comparative Example 1. The reaction pressure was maintained at 5 bar, and oxygen was supplied in excess of approximately 1.2 times the theoretical stoichiometric amount of 1 mole of oxygen (O₂) per 2 moles of deuterium (D₂). As a result, when reaction conditions were not sufficiently secured, the recovery rate of heavy water (D₂O) remained at approximately 40% or less, and a heavy water recovery rate of approximately 95% or more was confirmed only under conditions where the reaction could proceed sufficiently. This implies that under catalyst-free conditions, it is difficult to stably complete the deuterium oxidation reaction through simple adjustment of reaction conditions alone, and the heavy water recovery efficiency is also significantly limited. These results support the fact that a configuration combining the application of a metal catalyst with high-temperature conditions of 800°C or higher, as proposed in the present invention, is an essential technical configuration for stably oxidizing and recovering deuterium within a short period of time.

[0125] division Whether or not a catalyst is used Catalyst composition Carrier jeon treatment Loading method Reaction temperature (°C) Time of stay Oxygen supply Deuterium conversion rate / Deuterium recovery rate Example 1 is available Pt Al₂O₃ doesn't exist Single carrier 800~900 0.6~1.8 seconds 1.2 times the theoretical amount Achieved 99% conversion rate Example 2-1 is available Pt Al₂O₃ doesn't exist Single carrier 850 0.2 seconds 1.3 times Reaction rate 89% / Recovery rate 86% Example 2-2 is available Pt-Pd alloy Al₂O₃ doesn't exist Single carrier 850 0.2 seconds 1.3 times Reaction rate 92% / Recovery rate 89% Examples 2-3 is available Pt-Pd alloy SiO₂-Al₂O₃ is available Single carrier 850 0.2 seconds 1.3 times Reaction rate 95% / Recovery rate 91% Examples 2-4 is available Pt-Pd alloy SiO₂-Al₂O₃ is available Stepwise loading 850 0.2 seconds 1.3 times Reaction rate 97% / Recovery rate 93% Example 3 is available Pt-Pd alloy SiO₂-Al₂O₃ is available Stepwise loading 900 Continuous operation 1.25 times 96% recovery rate Comparative Example 1 doesn't exist - - - - 850 0.2 seconds 1.2 times Conversion rate approximately 40% Comparative Example 2 doesn't exist - - - - 600 - 1.2 times Recovery rate of approximately 40% or less under insufficient reaction conditions, and approximately 95% or more under sufficient reaction conditions.

[0127] According to the results of Table 2 above and the examples and comparative examples, it can be confirmed that the deuterium recovery process of the present invention can stably oxidize and convert deuterium into heavy water (D₂O) by combining high-temperature conditions of 800°C or higher and short residence time conditions under the application of a metal catalyst and an excess supply of oxygen. In particular, from the results of Example 1, it was confirmed that under high-temperature conditions, the oxidative conversion of deuterium proceeds almost completely even with a short residence time, thereby proving the effectiveness of the high-temperature conditions specified in the present invention. Furthermore, according to Examples 2-1 to 2-4, it can be confirmed that the application of an alloy catalyst, the use of a composite support, support pretreatment, and control of the catalyst surface composition through stepwise loading improve the deuterium conversion rate and the heavy water recovery rate stepwise. On the other hand, according to Comparative Examples 1 and 2, when a metal catalyst is not used, the oxidative conversion of deuterium and the recovery of heavy water are significantly limited unless sufficient reaction conditions are secured, confirming that the metal catalyst-based high-temperature oxidation process proposed in the present invention is an essential technical configuration for deuterium recovery.

[0128] In addition, from the continuous operation results of Example 3, it was confirmed that the deuterium recovery process of the present invention maintains a high recovery rate and reproducibility even under continuous operation conditions, and thus possesses process reliability applicable to industrial processes.

[0129] Although preferred embodiments of the present invention have been described above, those skilled in the art will understand that various modifications and changes can be made to the present invention without departing from the technical spirit of the invention as described in the following claims.

Claims

Claim 1 A deuterium recovery process using an oxidation reaction of deuterium, comprising: a step of supplying a gas containing deuterium (D₂) that is discharged or remains in an industrial process; a step of converting the deuterium into heavy water (D₂O) by oxidizing the deuterium; and a step of recovering the heavy water; wherein the oxidation reaction is characterized by contacting the deuterium with a metal oxidizing agent comprising at least one of a gas containing oxygen (O2) or oxygen and a copper oxide, an iron oxide, a manganese oxide, or a nickel oxide, and the reaction is performed under controlled conditions of reaction temperature, reaction pressure, and gas flow rate. Claim 2 delete Claim 3 A deuterium recovery process using an oxidation reaction of deuterium according to claim 1, wherein the oxidation reaction is carried out in the presence of a metal catalyst comprising one or more selected from platinum (Pt), palladium (Pd), ruthenium (Ru), iridium (Ir), nickel (Ni), cobalt (Co), or alloys thereof, and the metal catalyst is provided in a form supported on a support and comprises 0.01 to 50 weight percent of a metal component based on the total weight of the catalyst. Claim 4 A deuterium recovery process using an oxidation reaction of deuterium, characterized in that, in claim 3, the metal catalyst is supported on an inorganic oxide or ceramic support, the support comprises one or more selected from alumina, silica, silica-alumina, zeolite, zirconia (ZrO₂), titania (TiO₂), ceria (CeO₂), magnesia (MgO), or a mixture thereof, and the amount of the metal catalyst supported is 0.1 to 50 weight% based on the support. Claim 5 A deuterium recovery process using an oxidation reaction of deuterium, characterized in that, in claim 1, the oxidation reaction is performed in a reactor designed such that the temperature range of 800°C or higher and the residence time of the reaction gas passing through the catalyst bed is 0.01 seconds or higher, and the reaction rate is controlled such that the deuterium is oxidized and converted for a period longer than the said residence time. Claim 6 A deuterium recovery process using an oxidation reaction of deuterium, characterized in that, in claim 1, the deuterium is supplied in the form of a mixed gas comprising nitrogen, hydrogen (H₂), deuteride hydrogen (HD), an inert gas, or a process residual gas, and the content of deuterium (D₂) in the mixed gas is 0.01 to 100 mol% relative to the total gas, and the oxidation reaction is performed under conditions in which the oxygen is supplied in excess of the theoretical amount, based on a theoretical stoichiometric amount of 1 mol of oxygen (O₂) per 2 mol of deuterium (D₂). Claim 7 A deuterium recovery process using an oxidation reaction of deuterium, characterized in that, in claim 1, the recovery process comprises converting deuterium in a combustible gaseous state into liquid deuterium (D₂O) through the oxidation reaction, and recovering the deuterium through a condensation or storage process. Claim 8 A deuterium recovery process using an oxidation reaction of deuterium, characterized in that, in claim 1, it further comprises a step of recovering the deuterium; and a step of reusing the deuterium recovered in the step of recovering the deuterium; in a deuterium production process or a deuterium concentration process.

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