Preparation methods of coprecipitated copper-manganese catalysts and preparation methods of ultrapure nitrogen gas

Abstract

To address the shortcomings of existing technologies, this invention provides a method for preparing a coprecipitated copper-manganese catalyst and a method for preparing ultrapure nitrogen. The method for preparing the coprecipitated copper-manganese catalyst includes the following steps: mixing copper and manganese metal salt solutions with an oxidant, adjusting the pH to 7.5-11, wherein the molar ratio of copper to manganese is (0.02-3):1; ultrasonically aging the coprecipitate for 20-40 minutes, followed by aging for 10-14 hours; obtaining a filter cake after filtration and washing; drying the filter cake overnight at 95℃-125℃, and then calcining it at 350℃-450℃ in a gaseous atmosphere for 3-5 hours to obtain the coprecipitated copper-manganese catalyst. The catalyst prepared by the method of this invention exhibits good catalytic activity, capable of simultaneously catalytically removing carbon monoxide and hydrogen at room temperature, maintaining a 100% H2 conversion rate for 4-8 hours, and maintaining a high CO conversion rate for more than 50 hours, demonstrating a very long effective duration that meets the long-term operation requirements of industrial production.

Description

Technical Field

[0001] This invention belongs to the field of industrial gas purification, specifically relating to a method for preparing a co-precipitated copper-manganese catalyst and a method for preparing ultrapure nitrogen. Background Technology

[0002] With the advancement of science and technology, industrial gases have become an indispensable basic element of the national economy, occupying a pivotal position in the strategic layout of the national economy. Especially under the wave of the electronic information technology era, the booming development of industries such as integrated circuits and display panels has further increased the demand for high-purity electronic gases. As an important component of bulk electronic gases, high-purity nitrogen is increasingly widely used in the integrated circuit and display panel industries, leading to a surge in demand. Currently, high-purity nitrogen is mainly obtained from nitrogen production units through cryogenic distillation. However, the gas obtained in this process is often mixed with permanent gaseous impurities such as H2 and CO. These impurities have weak physical adsorption, strong chemical inertness, and require harsh phase transition conditions, making it difficult for existing processes to achieve efficient deep removal. With the increasing demands for high-purity gas purity and the continuous advancement of dual-carbon goals, the control of impurity content in gases and energy consumption in purification processes is becoming increasingly stringent. Therefore, the development of efficient nitrogen purification technologies is particularly important.

[0003] Currently, cryogenic distillation, as the mainstream nitrogen production process, can reduce the impurity content in nitrogen to the ppm level, meeting the requirements of the national standard GB / T8979-2008. However, as the "lifeblood" of the electronics and information industry, ultrapure nitrogen requires a purity level of ppb for advanced node wafer production lines below 7nm. Currently, the technology for economically producing ppb-level ultrapure nitrogen is mainly mastered by a few companies.

[0004] While precious metals generally possess excellent low-temperature catalytic oxidation performance, significant technical bottlenecks remain in the removal of low-concentration pollutants, such as in the preparation of ultrapure nitrogen. For example, platinum (Pt)-based catalysts, although capable of room-temperature catalytic oxidation of carbon monoxide (CO), struggle to efficiently remove low-concentration CO (<500 ppm) under low-temperature drying conditions and lack the ability to catalytically oxidize hydrogen (H2) at room temperature. To overcome these shortcomings, researchers often introduce other precious metals such as gold (Au) and palladium (Pd) to construct composite systems, thereby enhancing the synergistic catalytic activity of the catalysts. However, the persistently high price of precious metal raw materials results in extremely high production costs for precious metal catalysts, severely hindering their economic viability for large-scale applications. Furthermore, even bimetallic catalysts composed of precious metals struggle to meet the requirements of simultaneously removing low concentrations of carbon monoxide and hydrogen during long-term industrial production processes. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a method for preparing a co-precipitated copper-manganese catalyst, comprising the following steps:

[0006] S1. Mix the solutions of copper and manganese metal salts with the oxidant and adjust the pH to 7.5-11, wherein the molar ratio of copper to manganese is (0.01-5):1;

[0007] S2. After ultrasonic aging of the co-precipitate for 20-40 minutes, age it for 10-14 hours.

[0008] S3. After filtration and washing, a filter cake is obtained;

[0009] S4. Dry the filter cake overnight at 95℃-125℃, and calcine it at 350℃-450℃ in a gaseous atmosphere for 3-5 hours to obtain the coprecipitated copper-manganese catalyst.

[0010] Preferably, the molar ratio of copper to manganese is (0.02-3):1.

[0011] Preferably, the oxidant includes one or more of potassium permanganate, hydrogen peroxide, sodium hypochlorite, ammonium nitrate, and ammonium persulfate.

[0012] Preferably, the copper metal salt is copper nitrate or copper acetate; the manganese metal salt is manganese nitrate or manganese acetate.

[0013] Preferably, in step S2, the ultrasonic aging time is 25-35 minutes; the aging time is 11-13 hours.

[0014] Preferably, in step S4, the gas in the gas atmosphere refers to any one or more combinations of nitrogen, air, carbon monoxide, and argon.

[0015] Preferably, in step S4, the calcination temperature is 380℃-410℃.

[0016] The present invention also provides a method for preparing ultrapure nitrogen gas, wherein air is compressed, dried and filtered, and then introduced into a reactor, the reactor being filled with the coprecipitated copper-manganese catalyst, and the gas flowing out of the reactor is then distilled to obtain ultrapure nitrogen gas.

[0017] The present invention also provides a method for preparing ultrapure nitrogen gas, wherein industrially purified nitrogen gas is dried and then introduced into a reactor, the reactor being filled with the co-precipitated copper-manganese catalyst, and ultrapure nitrogen gas is obtained after passing through the reactor.

[0018] The coprecipitated copper-manganese catalyst prepared by the method of the present invention has a strong catalytic ability. It can simultaneously catalyze the removal of carbon monoxide and hydrogen at room temperature, maintain 100% H2 conversion for 4-8 hours, maintain high CO conversion for more than 50 hours, and has a very long effective time, which can meet the long-cycle operation requirements of industrial production. Attached Figure Description

[0019] The above and other objects, features, and advantages of the present invention will become clearer from the more detailed description of the preferred embodiments illustrated in the accompanying drawings. Throughout the drawings, the same reference numerals indicate the same parts, and the drawings are not intentionally drawn to scale with actual dimensions; the focus is on illustrating the gist of the invention.

[0020] Figure 1 This is a schematic diagram of the preparation process of ultrapure nitrogen provided by the present invention.

[0021] Figure 2 A process flow diagram of the gas purification method provided by the present invention. Detailed Implementation

[0022] The technical solution of the present invention will be further described in detail below with reference to specific embodiments, so that those skilled in the art can better understand the present invention and implement it. However, the embodiments are not intended to limit the present invention.

[0023] This invention provides a method for preparing a co-precipitated copper-manganese catalyst, comprising the following steps:

[0024] S1. Mix copper and manganese metal salt solutions with the oxidant, adjust the pH to 7.5-11, and the molar ratio of copper to manganese is (0.01-5):1;

[0025] S2. After ultrasonic aging of the co-precipitate for 20-40 minutes, age it for 10-14 hours.

[0026] S3. After filtration and washing, a filter cake is obtained;

[0027] S4. Dry the filter cake overnight at 95℃-125℃, and then calcine it at 350℃-450℃ in air for 3-5 hours to obtain a coprecipitated copper-manganese catalyst.

[0028] The catalyst prepared in this invention uses an oxide of interacting Cu and Mn as the active component. Through the synergistic effect of the composite metal oxides based on these two metal elements, Cu and Mn oxides readily generate lattice distortions, and manganese oxides form more defects. These defects act as oxygen vacancies, thereby enhancing the ability to release or capture oxygen molecules. CuO, as the active site, receives lattice oxygen and active oxygen from MnO2, a transition metal, enhancing the catalytic oxidation activity of H2 and CO. This makes it not only effective at removing carbon monoxide but also usable as a catalyst for removing hydrogen. Furthermore, it can simultaneously catalyze the removal of both carbon monoxide and hydrogen from feed gases containing both impurities. Even for feed gases with a higher carbon monoxide concentration than hydrogen, it can effectively remove carbon monoxide while ensuring long-term catalytic removal of hydrogen.

[0029] The catalyst prepared by this invention can be used for the deep removal of carbon monoxide and hydrogen from air, and can also be used to purify carbon monoxide and hydrogen from nitrogen, argon, and helium. It provides new catalytic support for the industrial production of high-purity electronic gases.

[0030] The catalyst prepared by this invention can be used in continuous flow reactors such as fixed beds, which have simple processes, low energy consumption, and can be operated continuously. The catalyst has a long effective reaction time.

[0031] The catalyst prepared by the method of the present invention does not use precious metals and has a relatively low copper ratio, which has the advantage of low cost and is suitable for large-scale application in the preparation of ultrapure gases.

[0032] In a preferred embodiment, in step S1, the molar ratio of copper to manganese is (0.02-3):1. Due to its strong catalytic ability for CO, the coprecipitated copper-manganese catalyst can simultaneously catalyze the removal of 10 ppm CO and 2 ppm H2 at room temperature, maintaining a 100% H2 conversion rate for 8 hours and CO conversion rate for 50 hours without deactivation.

[0033] The catalyst prepared by this invention has excellent catalytic effects on carbon monoxide and hydrogen with a low copper content, which greatly saves costs.

[0034] In a preferred embodiment, the oxidant includes one or more of potassium permanganate, hydrogen peroxide, sodium hypochlorite, ammonium nitrate, and ammonium persulfate. In a more preferred embodiment, the oxidant is potassium permanganate.

[0035] In a preferred embodiment, the oxidant contains a supporting ion, which is one or more selected from hydrogen ions, potassium ions, sodium ions, lithium ions, and ammonium ions. In a more preferred embodiment, the supporting ion is a potassium ion.

[0036] In a preferred embodiment, the copper metal salt is copper nitrate or copper acetate; the manganese metal salt is manganese nitrate or manganese acetate.

[0037] In a preferred embodiment, the ultrasonic aging time in step S2 is 25-35 minutes.

[0038] In a preferred embodiment, in step S2, the aging process lasts for 11-13 hours.

[0039] In a preferred embodiment, the calcination temperature in step S4 is 380℃-410℃.

[0040] In a preferred embodiment, the prepared coprecipitated copper-manganese catalyst is filled into a room temperature purification stationary reactor, which is operated at 20°C-50°C.

[0041] In a preferred embodiment, the prepared coprecipitated copper-manganese catalyst is filled into a high-pressure intermittent static reactor, the working pressure of which is 0.2-50 bar.

[0042] refer to Figure 1 This invention provides a method for preparing ultrapure nitrogen gas, comprising the following steps:

[0043] S11, Compress the air.

[0044] S12. Dry and filter the compressed air.

[0045] S13. The filtered gas is passed into a reactor filled with a catalyst. The catalyst in the reactor is a coprecipitated copper-manganese catalyst prepared by the preparation method of any embodiment of the present invention. The concentration of hydrogen and carbon monoxide in the gas flowing out of the reactor is less than 1 ppb.

[0046] S14. The gas is distilled to obtain ultrapure nitrogen and oxygen.

[0047] refer to Figure 2 The present invention also provides a gas purification method, comprising the following steps:

[0048] S21. Obtain industrial purified gas.

[0049] S22. The industrial purified gas is dried.

[0050] S23. The dried gas is passed into a reactor filled with a co-precipitated copper-manganese catalyst prepared by the method of any embodiment of the present invention. After passing through the reactor, an ultrapure gas with carbon monoxide and hydrogen contents of less than 1 ppb is obtained. In this embodiment, the industrial purification gas is an inert gas, such as nitrogen, argon, or helium.

[0051] In a preferred embodiment, the reactor can be a high-pressure intermittent static reactor with an operating pressure of 0.2-50 bar, and in a more preferred embodiment, the operating pressure is 0.2-20 bar.

[0052] In a preferred embodiment, the reactor can be a room temperature purification stationary reactor, which operates at 20°C-50°C.

[0053] In a preferred embodiment, the reactor may be a continuous flow reactor such as a fixed bed reactor.

[0054] In order to gain a better understanding of the technical solution of the present invention, several preferred embodiments are listed below for further detailed description.

[0055] Example 1:

[0056] Copper acetate and manganese acetate were mixed in a 3:1 molar ratio to prepare an aqueous solution. Potassium permanganate (potassium permanganate: manganese acetate molar ratio = 5:6) was added to the aqueous solution to adjust the pH to about 8. The coprecipitate was ultrasonically aged for 30 minutes, then stirred and aged at 30°C for 12 hours, filtered and washed to obtain a filter cake. The filter cake was dried overnight at 105°C and then calcined at 400°C in an air atmosphere for 4 hours to obtain a certain proportion of coprecipitated copper-manganese catalyst.

[0057] Example 2

[0058] Copper acetate and manganese acetate were mixed in a molar ratio of 0.1:1 to prepare an aqueous solution. Potassium permanganate (potassium permanganate: manganese acetate molar ratio = 5:6) was added to the aqueous solution to adjust the pH to about 8. The coprecipitate was ultrasonically aged for 30 minutes, then stirred and aged at 30°C for 12 hours, filtered and washed to obtain a filter cake. The filter cake was dried overnight at 105°C and then calcined at 400°C in an air atmosphere for 4 hours to obtain a certain proportion of coprecipitated copper-manganese catalyst.

[0059] Example 3

[0060] Copper acetate and manganese acetate were mixed in a molar ratio of 0.02:1 to prepare an aqueous solution. Potassium permanganate (potassium permanganate: manganese acetate molar ratio = 5:6) was added to the aqueous solution to adjust the pH to about 8. The coprecipitate was ultrasonically aged for 30 minutes, aged at 30°C for 12 hours, filtered and washed to obtain a filter cake. The filter cake was dried overnight at 105°C and then calcined at 400°C in an air atmosphere for 4 hours to obtain a certain proportion of coprecipitated copper-manganese catalyst.

[0061] Comparative Example 1

[0062] The difference from Example 2 is that the potassium permanganate in Example 2 is replaced with a tetramethylhydroxylamine solution (tetramethylhydroxylamine: manganese acetate molar ratio = 5:6), and the rest of the preparation method is the same as in Example 2.

[0063] Comparative Example 2

[0064] Unlike Example 2, in Comparative Example 2, manganese acetate was replaced with cerium nitrate, while the rest of the preparation methods were the same as in Example 2.

[0065] Comparative Example 3

[0066] Copper acetate and manganese acetate were mixed in a molar ratio of 0.02:1 to prepare an aqueous solution. Potassium permanganate was added to the aqueous solution to adjust the pH to about 8. The solution was then directly filtered and washed to obtain a filter cake. The filter cake was dried overnight at 105°C and then calcined at 150°C in an air atmosphere for 4 hours to obtain a certain proportion of coprecipitated copper-manganese catalyst.

[0067] Comparative Example 4

[0068] Copper acetate and manganese acetate were mixed in a molar ratio of 0.02:1 to prepare an aqueous solution. Potassium permanganate was added to the aqueous solution to adjust the pH to about 8. The coprecipitate was ultrasonically aged for 30 minutes, then directly filtered and washed to obtain a filter cake. The filter cake was dried overnight at 105°C and then calcined at 150°C in an air atmosphere for 4 hours to obtain a certain proportion of coprecipitated copper-manganese catalyst.

[0069] Comparative Example 5

[0070] Copper acetate and manganese acetate were mixed in a molar ratio of 0.02:1 to prepare an aqueous solution. Potassium permanganate was added to the aqueous solution to adjust the pH to about 8. The coprecipitate was ultrasonically aged for 30 minutes and then aged for 48 hours. The filter cake was obtained by filtration and washing. The filter cake was dried overnight at 105°C and then calcined at 650°C in an air atmosphere for 4 hours to obtain a certain proportion of coprecipitated copper-manganese catalyst.

[0071] Comparative Example 6

[0072] Copper acetate and manganese acetate were mixed in a 4:1 molar ratio to prepare an aqueous solution. Potassium permanganate was added to the aqueous solution to adjust the pH to about 8. The coprecipitate was ultrasonically aged for 30 minutes, then stirred and aged at 30°C for 12 hours, filtered and washed to obtain a filter cake. The filter cake was dried overnight at 105°C and then calcined at 400°C in an air atmosphere for 30 hours to obtain a certain proportion of coprecipitated copper-manganese catalyst.

[0073] Comparative Example 7

[0074] A powdered catalyst was synthesized using a sol-gel combustion-assisted method. The molar ratio of copper to manganese was 1 / 10. The required amounts of magnesium acetate hydrate, copper acetate hydrate, manganese acetate hydrate, and citric acid monohydrate were dissolved in deionized water. The molar ratio of citric acid to copper ions was 2:1, and the molar ratio of citric acid to manganese ions was 60:1.

[0075] Next, the solution was stirred in an oil bath at 80°C for 5 hours and dried at 90°C for 2 hours. The dried sample was ground and sieved to obtain samples with a specific diameter range. Then, the sample was dried overnight at 110°C to obtain powder or spherical particle morphology, depending on the type and composition of the precursor metal. Finally, the obtained sample was calcined in a 21% oxygen (nitrogen balance, hereinafter referred to as air) stream, with the temperature raised to 450°C at a heating rate of 1°C / min and held for 10 hours to obtain the catalyst.

[0076] Example of effect

[0077] (1) At room temperature (25°C) and atmospheric pressure, the catalysts prepared in Examples 1-3 and Comparative Examples 1-6 were pretreated in flowing dry air at 290°C for 45 minutes and then cooled to room temperature. This ensured that the catalyst surface was clean, dry, and in a consistent initial state, avoiding the influence of previously adsorbed moisture or other gases on the experimental results. The treated catalysts (0.2 g) from different examples and comparative examples were respectively packed into a fixed-bed reactor. The equilibrium gas was air, with air containing 2 ppmvH2 and 10 ppmvCO used as the feed gas, flowing at a mass hourly space velocity (HHSV) of 4000 h⁻¹. -1 The residence time of the feed gas in the reactor is 0.3 seconds, and the concentration of H2 at the outlet is detected using helium ion chromatography. Here, "time" refers to the time span from the start of the feed gas flow into the reactor, measuring the CO / H2 content at the outlet of the reaction tube. The time span from when CO / H2 is detected at the outlet of the reaction tube is the CO / H2 breakthrough time. The CO / H2 content is detected using helium ion chromatography. The carbon monoxide breakthrough time and hydrogen breakthrough time measured for different catalysts are shown in Table 1.

[0078] Table 1

[0079]

[0080] As can be seen from the data in Table 1, the co-precipitated copper-manganese catalysts prepared in Examples 1-3 of this invention exhibit strong catalytic activity, capable of simultaneously removing 2 ppm H2 and 10 ppm CO at room temperature, maintaining 100% H2 conversion for 4-8 hours and CO conversion for more than 50 hours. The catalytic activity is long-lasting, with a very long effective operating time, meeting the long-cycle operation requirements of industrial production. In particular, the catalyst prepared in Example 2 achieves H2 conversion for 8 hours while maintaining a CO conversion rate greater than 50 hours, demonstrating remarkable effectiveness.

[0081] In Comparative Example 1, the oxidant was replaced with tetramethylhydroxylamine solution instead of potassium permanganate. Since no suitable supporting ion was selected, the overall catalytic activity was relatively poor.

[0082] In Comparative Example 2, cerium nitrate and copper acetate were used to prepare the catalyst. The synergistic effect between the two was poor, resulting in relatively poor overall catalytic activity.

[0083] In Comparative Example 3, the catalyst did not undergo ultrasonic aging and stirring aging, resulting in very low catalyst activity and difficulty in achieving CO and H2 removal. This indicates that ultrasonic aging and stirring aging have a significant impact on catalyst activity.

[0084] In Comparative Example 4, there was no aging and stirring step, and the calcination temperature was only 150℃. The catalyst activity was very low, indicating that the calcination temperature was too low and had a significant impact on the catalyst activity.

[0085] In Comparative Example 5, the aging time was relatively long and the calcination temperature was as high as 650℃, resulting in very low catalyst activity. This indicates that both excessively long aging time and excessively high calcination temperature will reduce catalyst performance.

[0086] In Comparative Example 6, the ratio of copper acetate to manganese acetate was 4:1, which exceeded the range of the present invention. The catalyst activity was very low, indicating that an unreasonable ratio of copper to manganese will reduce the activity of the catalyst.

[0087] Comparative Example 7 used the gel method to prepare the copper-manganese catalyst, and the prepared catalyst had very low activity.

[0088] In summary, the preparation method provided by this invention is reasonable, and the catalyst obtained can simultaneously catalytically remove low concentrations of hydrogen and carbon monoxide at room temperature, making it suitable for the purification of ultrapure nitrogen. High-purity nitrogen is mainly obtained through cryogenic distillation, but this method often results in the presence of low concentrations of carbon monoxide and hydrogen as permanent impurities, which are difficult to remove. The catalyst prepared by this invention can simultaneously catalytically remove low concentrations of hydrogen and carbon monoxide at room temperature, and it maintains a relatively long effective reaction time for both hydrogen and carbon monoxide. This makes it suitable for the long-cycle operation requirements of industrial ultrapure nitrogen purification, meeting the requirements for industrial ultrapure nitrogen purification and providing sufficient ultrapure nitrogen for the fabrication of advanced node wafers below 7nm.

[0089] (2) The catalyst (0.2g) prepared in Examples 1-3 was filled into a batch reactor. The reactor was operated at 20℃-50℃ and statically removed 10ppmv CO and 2ppmv H2 at 5bar pressure. The test results are shown in Table 2.

[0090] Table 2

[0091]

[0092] As shown in Table 2, when the catalyst prepared by the method of this invention is used to remove impurities under intermittent pressurized conditions at room temperature, with the introduction of 10 ppm CO and 2 ppm H2, the carbon monoxide concentration was detected to be 1.2 ppm-1.5 ppm and the hydrogen concentration to be 102 ppb-154 ppb after 5 minutes. This indicates that the impurity concentration has significantly decreased after 5 minutes, demonstrating that the catalyst is active and has begun to work, but has not yet completely purified the gas. At 20 minutes, the impurity concentration drops sharply, proving that the catalyst is continuously and effectively removing hydrogen and carbon monoxide simultaneously over time, and the degree of purification increases with time. At 40 minutes, the concentrations of hydrogen and carbon monoxide are less than 1 ppb. This demonstrates that the catalyst prepared by the method of this invention can simultaneously remove low concentrations of CO and H2 at room temperature. This provides a usable catalyst for the efficient and deep purification of high-purity industrial gases and even electronic-grade industrial gases.

[0093] (3) The catalyst (0.2 g) prepared in Examples 1-3 was placed in a fixed-bed reactor, and air containing 400 ppmv H2 and 200 ppmv CO was used as feed gas, with a mass hourly space velocity of 4000 h⁻¹. -1The residence time of the feed gas in the reactor was 0.3 seconds, and the concentration of H2 at the outlet was detected using helium ion chromatography. Here, "time" refers to the time span from the start of the feed gas flow into the reactor, measuring the CO / H2 content at the outlet of the reaction tube, until H2 is detected at the outlet of the reaction tube; this time span is the CO / H2 breakthrough time. The CO / H2 content was detected using helium ion chromatography. The test results are shown in Table 3.

[0094] Table 3

[0095]

[0096] As shown in Table 3, the catalyst prepared by the method of this invention can simultaneously ensure the permeation time of both carbon monoxide and hydrogen when the hydrogen concentration is higher than the carbon monoxide concentration, with the hydrogen permeation time reaching 0.8-1.1 hours. This indicates that the catalyst prepared by this invention can also ensure the simultaneous removal of hydrogen and carbon monoxide under conditions where the hydrogen concentration is higher than the carbon monoxide concentration, maintaining a hydrogen permeation time of 0.8-1.1 hours, which is a very significant effect.

[0097] (4) Place the catalyst (0.2 g) prepared in Examples 1-3 into a fixed-bed reactor. Introduce air containing 2 ppmv H2 and 200 ppmv CO at a space velocity of 4000 h⁻¹. -1 The residence time of the feed gas in the reactor was 0.3 seconds. The concentrations of H2 and CO at the outlet were detected using helium ion chromatography. Here, "time" refers to the time span from the start of the feed gas flow into the reactor, measuring the CO / H2 ratio at the outlet of the reaction tube. The time span from when CO / H2 is detected at the outlet of the reaction tube is the CO / H2 breakthrough time. The CO / H2 content was detected using helium ion chromatography. The measured CO breakthrough time and hydrogen breakthrough time are shown in Table 4.

[0098] Table 4

[0099]

[0100] As shown in Table 4, under the conditions of 2 ppmvH2 and 200 ppmvCO as raw materials, it can not only ensure a long effective reaction time for carbon monoxide, but also remove low concentrations of hydrogen.

[0101] Generally, under conditions where the carbon monoxide concentration is significantly higher than the hydrogen concentration in the feed gas, hydrogen removal is impossible due to competitive adsorption. However, when the catalyst prepared by the method of this invention is used to remove feed gas with a carbon monoxide concentration significantly higher than the hydrogen concentration, although the effective action time for hydrogen removal decreases, it still achieves an effective action time of 0.8-1.1 hours. This indicates that the catalyst prepared by this invention has good carbon monoxide tolerance and can still ensure the simultaneous removal of carbon monoxide and hydrogen under harsh conditions of high carbon monoxide concentration, with a very significant effect on the simultaneous removal of both.

[0102] (5) At room temperature (25°C) and normal pressure, the catalysts prepared in each example and comparative example were pretreated in flowing dry air at 60°C for 45 minutes, and then cooled to room temperature. The pretreated catalyst (0.2 g) was placed in a fixed-bed reactor, and feed gas containing different concentrations of H2 was introduced at a mass hourly space velocity (MSV) of 4000 h⁻¹. -1 The residence time of the feed gas in the reactor was 0.3 seconds, and the concentration of H2 at the outlet was detected using helium ion chromatography. Removal tests were conducted using different concentrations of H2 (50 ppb, 1 ppm, 2 ppm, 10 ppm, 400 ppm) as the feed gas, with dry air as the equilibrium gas. The removal effects of different embodiments and comparative examples on different concentrations of hydrogen were tested. Here, "time" refers to the time span from the start of the feed gas flow into the reaction tube, detecting the H2 content at the outlet of the reaction tube, until H2 is detected at the outlet of the reaction tube (limit of quantitation 20 ppb). This time span is the H2 breakthrough time. The results are shown in Table 5.

[0103] Table 5

[0104]

[0105] As shown in Table 5, the catalyst prepared in this embodiment of the invention exhibits a long hydrogen permeation time for hydrogen of different concentrations, enabling deep removal of hydrogen from a wide range of concentrations in the gas. The effective action time for removing 50 ppb of hydrogen is greater than 24 hours, allowing for continuous deep removal of low-concentration hydrogen (50 ppb) in industrial production. The catalyst prepared in Example 2 of this invention maintains a 100% hydrogen conversion rate for over 16 hours under conditions of room temperature, high space velocity, extremely short residence time, and feed gas concentration as low as 2 ppm, demonstrating excellent hydrogen catalytic activity and long-term operational stability. For the same material, the lower the hydrogen concentration, the longer the permeation time; as the concentration increases, the permeation time generally shortens. This is because at room temperature, H2 is converted to H2O and adsorbed on the active sites, gradually accumulating and occupying reaction sites. The catalyst prepared in this embodiment of the invention not only exhibits superior catalytic activity for removing low-concentration hydrogen and can remove hydrogen for extended periods, but also has a wide range of hydrogen concentrations that can be removed, and the catalyst exhibits good stability.

[0106] The preparation methods in Comparative Examples 1-6 are different from those in this invention. The catalysts prepared have poor hydrogen removal performance. On the one hand, they do not have a long effective time for removing low-concentration hydrogen. On the other hand, when the hydrogen concentration is ≥10ppm, the activity is basically lost. The concentration range of hydrogen that can be removed is narrow and cannot be applied to long-term and stable hydrogen removal in industrial production.

[0107] (6) The catalyst (0.2g) was statically removed in a batch reactor. H2 of different concentrations (50ppb, 1ppm, 2ppm, 10ppm, 400ppm) was introduced into the reactor and pressurized to 5 bar. The reaction was carried out for 2 hours. The gas in the reactor was sampled for component analysis. The results are shown in Table 6.

[0108] Table 6

[0109]

[0110] As shown in Table 6, the catalysts prepared by the methods in Examples 1-3 of this invention exhibit good removal effects for hydrogen concentrations of 50 ppb, 1 ppm, 2 ppm, 10 ppm, and 400 ppm. After 2 hours of reaction, the hydrogen concentration can be reduced to <1 ppb, achieving deep removal of hydrogen over a wide range of concentrations, meeting the requirements of industrial production. The preparation methods in Comparative Examples 1-6 differ from those of this invention, and the catalysts obtained from these methods show poor hydrogen removal effects. For hydrogen concentrations of 1 ppm and above, good removal effects are difficult to achieve after 2 hours of reaction. This indicates that the catalysts prepared by the method provided by this invention can achieve good removal effects for hydrogen concentrations from 50 ppb to 400 ppm.

[0111] (7) At room temperature (25°C) and normal pressure, the catalysts prepared in each example and comparative example were pretreated in flowing dry air at 60°C for 45 minutes and then cooled to room temperature. The pretreated catalyst (0.2 g) was placed in a fixed-bed reactor, and air containing different concentrations of carbon monoxide was introduced at a mass hourly space velocity (MSV) of 4000 h⁻¹. -1 The residence time of the feed gas in the reactor was 0.3 seconds. Tests were conducted using different concentrations of CO (50 ppb, 10 ppm, 400 ppm, 1% CO, and 10% CO, with dry air as the equilibrium gas) as feed gas to evaluate the removal efficiency of different embodiments and comparative examples. The CO concentration at the outlet was detected using helium ion chromatography. "Time" refers to the CO breakthrough time, measured from the start of the feed gas flow into the reaction tube until CO was detected at the outlet (limit of quantitation 20 ppb). The test results are shown in Table 7.

[0112] Table 7

[0113]

[0114] As shown in Table 7, the catalysts prepared by the methods in Examples 1-3 of this invention exhibit good removal effects on carbon monoxide concentrations of 20 ppb, 10 ppm, and 400 ppm, with longer reaction times and permeation times exceeding 50 hours. Furthermore, under conditions of 1% CO concentration, the catalysts prepared in these examples can maintain 100% CO conversion for 1.2-2 hours, and the permeation time for 10% CO is 0.6-1.1 hours. This indicates that the catalysts prepared by the methods of this invention not only possess deep removal capabilities for low-concentration carbon monoxide but also maintain a certain reaction time even at higher carbon monoxide concentrations, demonstrating good tolerance. They exhibit excellent catalytic activity and stability, achieving efficient room-temperature removal of CO from ultrapure gases over a wide concentration range, and can be applied to long-cycle carbon monoxide removal in industrial production.

[0115] The preparation methods in Comparative Examples 1-6 are different from those of the present invention. The catalysts prepared by these examples have a shorter effective time for deep removal of low concentrations of carbon monoxide and do not have the ability to withstand the removal of high concentrations of carbon monoxide.

[0116] (8) The catalyst (0.2 g) prepared in the examples and comparative examples was placed in a batch reactor for static removal. The reactor was pressurized to 10 bar with different concentrations of CO and reacted for 1 hour. The gas in the reactor was sampled for component analysis, and the results are shown in Table 8.

[0117] Table 8

[0118]

[0119] As can be seen from the data in Table 8, the catalysts prepared by the methods in Examples 1-3 of this invention can achieve efficient removal of carbon monoxide from ultrapure gas to below 1 ppb at room temperature under a wide range of carbon monoxide concentrations. The preparation methods of Comparative Examples 1-6 differ from those of this invention, and the catalysts obtained from these methods do not exhibit good carbon monoxide removal performance. This indicates that the preparation method of this invention is reasonable, and the catalysts obtained can reduce the concentration of these CO impurities to below 1 ppb under room temperature and static pressure conditions for a certain reaction time, meeting the purification requirements of industrial production.

[0120] The above are merely preferred embodiments of the present invention and do not limit the patent scope of the present invention. Any equivalent structural or procedural transformations made based on the content of the present invention specification, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. A method for preparing ultrapure nitrogen gas, characterized in that, Air is compressed, dried, and filtered before being introduced into a reactor filled with a co-precipitated copper-manganese catalyst. The reactor operates at 20°C-50°C. After carbon monoxide and hydrogen are removed from the air in the reactor, the outflowing gas is further purified by distillation to obtain ultrapure nitrogen gas with hydrogen and carbon monoxide concentrations both less than 1 ppb. The preparation method of the co-precipitated copper-manganese catalyst includes the following steps: S1. Mix the solutions of copper and manganese metal salts with the oxidizing agent and adjust the pH to 7.5-11, wherein the molar ratio of copper to manganese is (0.02-3):1; the oxidizing agent is potassium permanganate; S2. After ultrasonic aging of the co-precipitate for 20-40 minutes, age it for 10-14 hours. S3. After filtration and washing, a filter cake is obtained; S4. The filter cake is dried overnight at 95℃-125℃ and calcined at 350℃-450℃ in a gaseous atmosphere for 3-5 hours to obtain a coprecipitated copper-manganese catalyst. The copper metal salt is copper nitrate or copper acetate; the manganese metal salt is manganese nitrate or manganese acetate. In step S4, the gas referred to in the gas atmosphere is air.

2. The method for preparing ultrapure nitrogen as described in claim 1, characterized in that, In step S2, the ultrasonic aging time is 25-35 minutes; the aging time is 11-13 hours.

3. The method for preparing ultrapure nitrogen as described in claim 1, characterized in that, In step S4, the calcination temperature is 380℃-410℃.

4. A method for preparing ultrapure nitrogen gas, characterized in that, Industrial purified nitrogen gas is dried and then introduced into a reactor filled with a co-precipitated copper-manganese catalyst. The reactor is operated at 20℃-50℃. After removing carbon monoxide and hydrogen from the industrial purified nitrogen gas in the reactor, ultrapure nitrogen gas with carbon monoxide and hydrogen concentrations of less than 1 ppb is obtained. The preparation method of the co-precipitated copper-manganese catalyst includes the following steps: S1. Mix the solutions of copper and manganese metal salts with the oxidizing agent and adjust the pH to 7.5-11, wherein the molar ratio of copper to manganese is (0.02-3):1; the oxidizing agent is potassium permanganate; S2. After ultrasonic aging of the co-precipitate for 20-40 minutes, age it for 10-14 hours. S3. After filtration and washing, a filter cake is obtained; S4. The filter cake is dried overnight at 95℃-125℃ and calcined at 350℃-450℃ in a gaseous atmosphere for 3-5 hours to obtain a coprecipitated copper-manganese catalyst. The copper metal salt is copper nitrate or copper acetate; the manganese metal salt is manganese nitrate or manganese acetate. In step S4, the gas referred to in the gas atmosphere is air.

5. The method for preparing ultrapure nitrogen as described in claim 4, characterized in that, In step S2, the ultrasonic aging time is 25-35 minutes; the aging time is 11-13 hours.

6. The method for preparing ultrapure nitrogen as described in claim 4, characterized in that, In step S4, the calcination temperature is 380℃-410℃.

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