Gas purification catalyst with improved carbon dioxide adsorption capacity and method for preparing the same

Abstract

The application discloses a gas purification catalyst capable of improving carbon dioxide adsorption capacity and a preparation method thereof. The gas purification catalyst is prepared by taking oxides of Ni, Mn, Co and Ag as active components, taking oxides of Ce, Ga and Mg as auxiliary agents, and taking activated carbon as a carrier. In particular, the sol-gel method is adopted to prepare nanoscale powder mixed with the active components and the auxiliary agents. The catalyst prepared by adding the activated carbon with a large specific surface area and porosity and a binder has uniform dispersion of the active components and the auxiliary agents and an increased number of active centers, thereby effectively improving the adsorption capacity of carbon dioxide gas under the premise of ensuring the impurity removal depth. Meanwhile, the application can avoid the penetration of metal ion impurities into product gas and can be widely applied to the preparation of ultrapure gas in the semiconductor industry.

Description

Technical Field

[0001] This invention relates to the field of high-purity gas purification technology, specifically to a gas purification catalyst that can improve carbon dioxide adsorption capacity and its preparation method. Background Technology

[0002] High-purity gases are essential raw materials for the electronics industry, widely used in the manufacturing processes of ultra-large-scale integrated circuits, liquid crystal displays, semiconductor light-emitting devices, and semiconductor materials. In high-end electronics, gas purity must be maintained above 6N (99.9999%), and some specialized processes even require purity above 9N (99.9999999%). Therefore, purification of ordinary gases is necessary. Previously, the purification of ordinary gases primarily employed catalytic adsorption methods. Catalysts oxidized reducing impurities in the gas into water and carbon dioxide, which were then removed by adsorbents. Once saturated, the adsorbents required desorption and regeneration before reuse. However, these adsorbents suffer from varying degrees of low adsorption capacity and shallow adsorption depth, and the separate use of two types of packing materials resulted in high production costs. Therefore, purification materials capable of removing impurities from gases in a single process have become a research hotspot in recent years.

[0003] Chinese invention patent application CN110756229A discloses a "method for preparing inert gas purification materials," which uses transition metal oxides or transition metal oxide ores as carriers to load rare metals such as palladium, platinum, and ruthenium. Not only is the production cost high, but the catalyst also requires stringent operating conditions; even trace amounts of sulfides in the raw material gas can lead to irreversible poisoning and deactivation of the catalyst.

[0004] Chinese invention patent application CN110280206A discloses "a multifunctional adsorbent and its preparation method and application," which uses Ni, Cu, Mn or their compounds as active components; the support is one or a mixture of several of alumina, silicon oxide, and titanium oxide. Chinese invention patent CN111974445 B discloses "an inert gas purification catalyst, raw material composition and preparation method," with active components including oxides of Ni, Cu, and Zn, and auxiliary agents including compounds of Li and / or compounds of B. Both of these purifiers use metallic copper as the main active component. When used for gas purification in the semiconductor industry, some copper ions will permeate into the product gas, causing an electrochemical effect and resulting in a decrease in product yield.

[0005] Chinese invention patent CN111905803 B discloses "an inert gas purification catalyst, raw material composition, and preparation method." The active components of the inert gas purification catalyst include oxides of Ni, V, and Zn, and the auxiliary agents include one or more compounds of Cr, P, and As. Although the prepared purifier achieves a high degree of impurity removal from the gas, its absorption capacity for carbon dioxide is low, only 1 / 2 to 1 / 10 of that for other impurities. In practical use, this low absorption capacity significantly shortens the catalyst's single-pass usage time, increases the frequency of regeneration after carbon dioxide adsorption saturation, directly reduces production efficiency, and increases production costs. Summary of the Invention

[0006] In order to solve the above-mentioned technical problems existing in the prior art, the present invention provides a gas purification catalyst that can improve the carbon dioxide adsorption capacity and a method for preparing the same.

[0007] The technical solution of this invention is: a gas purification catalyst that can improve the adsorption capacity of carbon dioxide, comprising an active component, an auxiliary agent, a support, and a binder. The active component is an oxide of Ni, an oxide of Mn, an oxide of Co, and an oxide of Ag. The auxiliary agent is an oxide of Ce, an oxide of Ga, and an oxide of Mg. The support is activated carbon. The mass percentage of Ni oxide is 5-50%, the mass percentage of Mn oxide is 10-30%, the mass percentage of Co oxide is 1-10%, the mass percentage of Ag oxide is 1-10%, the mass percentage of the auxiliary agent Ce oxide, Ga oxide, and Mg oxide is 2-10%, the mass percentage of the support is 15-30%, and the mass percentage of the binder is 2-10%.

[0008] A method for preparing the above-mentioned gas purification catalyst that can improve carbon dioxide adsorption capacity is carried out according to the following steps:

[0009] a. Dissolve a measured amount of Ni salt, Mn salt, Co salt and Ag salt in deionized water, add citric acid, then add ammonia to adjust the pH to 6, and react at 50-80℃ for 1-3 hours to obtain a metal sol, wherein the Ni salt, Mn salt, Co salt and Ag salt are acetate or nitrate;

[0010] b. Dissolve Ce salt, Ga salt and Mg salt in deionized water, add citric acid, stir evenly at room temperature, and then stir at 60-80℃ for 1-2 hours to obtain auxiliary agent sol, wherein the Ce salt, Ga salt and Mg salt are hydrochloride salts or nitrate salts;

[0011] c. Mix the metal sol and the auxiliary sol, stir at room temperature, sonicate for 6-8 hours, let stand at room temperature for 24 hours, and then place in an 80℃ constant temperature water bath for at least 3 hours to obtain a gel.

[0012] d. The gel is dried and calcined to obtain nano-sized powder. The nano-sized powder, activated carbon and binder are then mixed evenly and extruded to obtain a gas purification catalyst.

[0013] This invention prepares a gas purification catalyst using oxides of Ni, Mn, Co, and Ag as active components, oxides of Ce, Ga, and Mg as auxiliary agents, and activated carbon as the support. Specifically, it employs a sol-gel method to prepare nanoscale powders containing a mixture of active components and auxiliary agents. By adding activated carbon with a large specific surface area and porous binder, the catalyst exhibits uniform dispersion of active components and auxiliary agents and an increased number of active centers, effectively improving the adsorption capacity of carbon dioxide gas while ensuring the depth of impurity removal. Furthermore, this invention prevents metal ion impurities from permeating into the product gas, making it widely applicable to the preparation of ultrapure gases in the semiconductor industry. Detailed Implementation

[0014] Comparative Example 1:

[0015] The catalyst was prepared according to the method of Example 1 of Chinese Invention Patent No. CN111905803 B: 9.5g of sodium chromate and 2.5g of sodium arsenate were ground in a ball mill and then added to 300ml of ethanol solution and sonicated for 2 hours; 167g of basic nickel carbonate, 13g of ammonium metavanadate and 5.2g of basic zinc carbonate were weighed, ground in a ball mill and mixed, and the mixture was added to the ethanol solution containing sodium chromate and sodium arsenate. The mixture was stirred at room temperature (25℃) for 6 hours, the solid was collected by filtration and dried, 20g of beta molecular sieve was weighed and thoroughly mixed with the dried catalyst active component and auxiliary agent mixture, and finally extruded into strips using aluminum sol with an aluminum content of 5% as a binder. After molding, the catalyst was naturally dried and then dried overnight in an oven at 110℃. It was then transferred to a muffle furnace with nitrogen protection gas and calcined at 350℃ for 6 hours to obtain gas purification catalyst No. 1.

[0016] Comparative Example 2:

[0017] a. Dissolve 200g of nickel nitrate hexahydrate, 50g of manganese nitrate, 20g of cobalt nitrate and 5g of silver nitrate in 500mL of deionized water, then add 250g of citric acid and stir until dissolved. Then add ammonia dropwise to adjust the pH to 6 and react at 80℃ for 1 hour to obtain a metal sol.

[0018] b. Dissolve 40g of zinc nitrate and 60g of lithium nitrate in 200mL of deionized water, add 100g of citric acid, stir evenly at room temperature, and then stir at 80℃ for 1 hour to obtain the auxiliary agent sol;

[0019] c. Mix the metal sol and the auxiliary sol, stir evenly at room temperature, then sonicate for 8 hours, let stand and age at room temperature for 24 hours, and then place in an 80°C constant temperature water bath for at least 3 hours to remove a large amount of solvent and obtain a gel.

[0020] d. The gel was dried and calcined to obtain nano-sized powder, which was then mixed evenly with 50g activated carbon and 45g binder, and extruded into strips to obtain gas purification catalyst No. 2. Example

[0021] The gas purification catalyst of the present invention, which can improve the carbon dioxide adsorption capacity, is prepared by following the steps below:

[0022] a. Dissolve 200g of nickel nitrate hexahydrate, 50g of manganese nitrate, 20g of cobalt nitrate and 5g of silver nitrate in 500mL of deionized water, then add 250g of citric acid and stir until dissolved. Then add ammonia dropwise to adjust the pH to 6 and react at 80℃ for 1 hour to obtain a metal sol.

[0023] b. Dissolve 30g of cerium nitrate, 10g of gallium nitrate and 60g of magnesium nitrate in 200mL of deionized water, add 100g of citric acid, stir evenly at room temperature, and then stir at 80℃ for 1 hour to obtain the auxiliary agent sol;

[0024] c. Mix the metal sol and the auxiliary sol, stir evenly at room temperature, then sonicate for 8 hours, let stand and age at room temperature for 24 hours, and then place in an 80°C constant temperature water bath for at least 3 hours to remove a large amount of solvent and obtain a gel.

[0025] d. The gel was dried and calcined to obtain nano-sized powder, which was then mixed evenly with 50g activated carbon and 45g binder, and extruded into strips to obtain gas purification catalyst No. 3. Example

[0026] The gas purification catalyst of the present invention, which can improve the carbon dioxide adsorption capacity, is prepared by following the steps below:

[0027] a. Dissolve 90g of nickel acetate, 45g of manganese acetate, 25g of cobalt acetate and 10g of silver acetate in 500mL of deionized water, then add 250g of citric acid and stir until dissolved. Then add ammonia dropwise to adjust the pH to 6 and react at 60℃ for 2 hours to obtain a metal sol.

[0028] b. Dissolve 17g of cerium chloride, 6g of gallium chloride and 38g of magnesium chloride in 200mL of deionized water, add 100g of citric acid, stir evenly at room temperature, and then stir at 60℃ for 2 hours to obtain the auxiliary agent sol;

[0029] c. Mix the metal sol and the auxiliary sol, stir evenly at room temperature, then sonicate for 6 hours, let stand and age at room temperature for 24 hours, and then place in an 80°C constant temperature water bath for at least 3 hours to remove a large amount of solvent and obtain a gel.

[0030] d. The gel was dried and calcined to obtain nano-sized powder, which was then mixed evenly with 60g of activated carbon and 37g of binder, and extruded into strips to obtain gas purification catalyst No. 4. Example

[0031] Take 200g of nickel nitrate, 50g of manganese nitrate, 20g of cobalt nitrate and 5g of silver nitrate, mix them for 3 hours, then add 30g of cerium nitrate, 10g of gallium nitrate and 60g of magnesium nitrate, and continue to mix for 3 hours. Dry and calcine the mixture to obtain powder, then mix it evenly with 60g of activated carbon and 37g of binder, compress it into tablets, and obtain gas purification catalyst No. 5.

[0032] experiment:

[0033] The catalyst samples prepared in Examples 1-2 and Comparative Examples 1-3 were subjected to experiments to test their impurity removal effects. The experimental methods are as follows:

[0034] Catalyst activation: Take 25 ml of catalyst sample, sieved to 20-40 mesh, and place it into a 1-inch stainless steel reaction tube. First, purge the pipeline and reaction tube with high-purity nitrogen at atmospheric pressure. After the entire evaluation system is free of oxygen, raise the temperature to 400℃ and run the gas at a space velocity of 5000 h⁻¹. -1 High-purity hydrogen was introduced for reduction. After 12 hours of reduction, high-purity nitrogen was used to purge and cool the catalyst to room temperature, thus completing the catalyst activation.

[0035] Preparation of raw material gas: Prepare evaluation raw material gas with different impurity concentrations according to experimental requirements. The raw material gas base gas is high-purity nitrogen gas, which contains impurities of 100ppm hydrogen, 100ppm oxygen, 100ppm carbon monoxide, 100ppm carbon dioxide, and 10ppm water.

[0036] Experimental procedure: At room temperature (25℃) and pressure (0-20 kPa), space velocity was 10000 h⁻¹ -1 The prepared feed gases were introduced separately. The impurity content of the gas at the reactor outlet was monitored online to obtain purification depth data for different gases. When the content of a certain impurity in the outlet gas exceeded 100 ppb, the catalyst was considered saturated for that impurity, and its adsorption capacity was calculated. The experimental results are shown in the table below:

[0037]

[0038] In the table, * indicates that the value is below the instrument's detection limit.

[0039] As can be seen from the table, the removal depth of impurities in the raw gas by Examples 1, 2, and 3 of the present invention is comparable to that of Comparative Examples 1 and 2. However, the adsorption capacities of carbon dioxide by Examples 1, 2, and 3 of the present invention are 30.6 mL / g, 32.1 mL / g, and 28.4 mL / g, respectively, which are significantly higher than those of Comparative Examples 1 and 2 (5.3 mL / g and 6.9 mL / g).

Claims

1. A nitrogen purification catalyst capable of improving carbon dioxide adsorption capacity, comprising an active component, an auxiliary agent, a support, and a binder, characterized in that: The active component is an oxide of Ni, an oxide of Mn, an oxide of Co, and an oxide of Ag; the auxiliary agent is an oxide of Ce, an oxide of Ga, and an oxide of Mg; and the support is activated carbon. The mass percentage of Ni oxide is 5-50%, the mass percentage of Mn oxide is 10-30%, the mass percentage of Co oxide is 1-10%, the mass percentage of Ag oxide is 1-10%, the mass percentage of the auxiliary agent Ce oxide, Ga oxide, and Mg oxide is 2-20%, the mass percentage of the support is 15-30%, and the mass percentage of the binder is 2-10%. The catalyst was prepared sequentially according to the following steps: a. Dissolve a measured amount of Ni salt, Mn salt, Co salt and Ag salt in deionized water, add citric acid, then add ammonia to adjust the pH to 6, and react at 50-80℃ for 1-3 hours to obtain a metal sol, wherein the Ni salt, Mn salt, Co salt and Ag salt are acetate or nitrate; b. Dissolve Ce salt, Ga salt and Mg salt in deionized water, add citric acid, stir evenly at room temperature, and then stir at 60-80℃ for 1-2 hours to obtain auxiliary agent sol, wherein the Ce salt, Ga salt and Mg salt are hydrochloride salts or nitrate salts; c. Mix the metal sol and the auxiliary sol, stir at room temperature, sonicate for 6-8 hours, let stand at room temperature for 24 hours, and then place in an 80℃ constant temperature water bath for at least 3 hours to obtain a gel. d. The gel is dried and calcined to obtain nano-sized powder. The nano-sized powder, activated carbon and binder are then mixed evenly and extruded to obtain a nitrogen purification catalyst.

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