Deoxidizing catalyst, its preparation method and application

Abstract

This invention belongs to the field of gas catalytic purification technology, specifically relating to a deoxygenation catalyst, its preparation method, and its application. The preparation method includes the following steps: 1) Impregnation: An alkali metal salt and a soluble transition metal salt are dissolved in water, the pH is adjusted to 1-2, then a solution containing soluble ruthenium salt and / or soluble silver salt is added, mixed evenly, and a spherical support is impregnated in the solution. The solvent is then removed, and the solution is calcined at high temperature to obtain the catalyst support; 2) Spraying: The catalyst support is placed in a coating machine, and a solution containing soluble platinum compound and / or soluble palladium compound is uniformly sprayed onto the surface of the catalyst precursor under rotational conditions. The catalyst is then dried and set aside for use; 3) The catalyst dried in step 2) is reduced and activated to obtain the final product. With a noble metal loading not exceeding 1.2‰ (wt), this deoxygenation catalyst can eliminate oxygen from hydrogen at room temperature, achieving an outlet oxygen concentration of less than 1 ppm.

Description

Technical Field

[0001] This invention belongs to the field of gas catalytic purification technology, specifically relating to a deoxygenation catalyst, its preparation method, and its application. Background Technology

[0002] In industries such as chemical engineering, metallurgy, and new energy, gases often require deoxygenation and purification to produce high-purity gases, protective gases, and qualified syngas. Chemical deoxygenation methods typically include chemical adsorption and catalytic combustion. Due to its relatively small processing capacity, chemical adsorption is suitable for deep deoxygenation of small flow rates of gases. Catalytic combustion is currently the most widely used deoxygenation method for industrial gases. The latter, based on its deoxygenation principle, can be further categorized into activated carbon-consuming, H2-consuming, CO-consuming, and hydrocarbon-consuming deoxygenation catalysts.

[0003] Deoxygenation catalysts include non-precious metal catalysts with molybdenum, nickel, and cobalt as the main active components, and precious metal catalysts with platinum and palladium as the main active components. Non-precious metal catalysts are mainly used for the hydrogenation and deoxygenation of organic matter, and are rarely used in gas purification, only occasionally in scenarios with high sulfur and chlorine content. Among precious metal-based catalysts, palladium as the main active component has been the subject of more research and application.

[0004] Chinese patent application 202211162480.2 discloses a method for preparing a hydrodeoxygenation catalyst. First, a mixture containing a support and a nitrogen-containing organic compound is prepared; then, the support and the nitrogen-containing organic compound are pyrolyzed under an inert atmosphere to obtain a modified support; finally, a transition metal is loaded using an impregnation method to prepare a bimetallic supported catalyst. This catalyst utilizes the coordination effect between the carbon-nitrogen compound and the metal component to improve the dispersibility of the metal component on the support surface.

[0005] Chinese patent application 201310630031.0 describes a catalyst prepared by impregnation using platinum and palladium as active components. Using methanol as a reducing agent, at a deoxygenation temperature of 180°C, the oxygen content decreased from 5% (VOL) to 0.061% (VOL).

[0006] As can be seen from the above, the preparation methods of currently available deoxygenation catalysts are cumbersome, and most of them cannot meet the oxygen removal efficiency requirements (<1ppm) in specific scenarios. For deoxygenation catalysts that can achieve oxygen removal efficiency of less than 1ppm, the amount of precious metals used is generally not less than 2wt%, and there are specific regulations regarding the content of expensive palladium, resulting in high costs for highly active deoxygenation catalysts. Therefore, developing deoxygenation catalysts with low precious metal content and high activity through innovative catalyst preparation methods is of practical significance. Summary of the Invention

[0007] In view of the shortcomings of the prior art, the purpose of this invention is to provide a deoxygenation catalyst, its preparation method and application. Under the condition that the noble metal loading of the deoxygenation catalyst is not higher than 1.2‰ (wt), the oxygen concentration at the outlet can be reduced to less than 1ppm when removing oxygen from hydrogen at room temperature.

[0008] Specifically, the present invention provides the following technical solutions:

[0009] This invention first provides a method for preparing a deoxygenation catalyst, comprising the following steps:

[0010] 1) Impregnation: Dissolve alkali metal salts and soluble transition metal salts in water, adjust the pH to 1-2, then add a solution containing soluble ruthenium salts and / or soluble silver salts, mix evenly, impregnate the spherical support in it, then remove the solvent, and calcine at high temperature to obtain the catalyst support;

[0011] 2) Spraying: The catalyst support is placed in a coating machine, rotated, and then a solution containing soluble platinum compound and / or soluble palladium compound is uniformly sprayed onto the surface of the catalyst precursor, and dried for later use;

[0012] 3) The catalyst dried in step 2) is reduced and activated to obtain the final product.

[0013] This invention employs a two-step preparation process of impregnation and spraying. First, a spherical carrier is impregnated in a mixed solution of alkali metal, transition metal, and ruthenium and / or silver. After curing, a solution containing platinum and palladium active components is sprayed onto the carrier using a spraying method. Finally, a highly active gas deoxygenation catalyst with low precious metal content is prepared, which is then reduced and activated before use.

[0014] Preferably, in step 1), the spherical carrier is spherical alumina or spheres with alumina as the main component, and the particle size of the spherical carrier is 3 mm or more. In this invention, the spheres with alumina as the main component refer to spheres with an alumina content of 80 wt% or more.

[0015] In existing technologies, spherical carriers with alumina as the main component and a diameter greater than 3 mm are mostly prepared by the rolling ball method, which results in defects on the carrier surface. When active components are directly loaded, obvious grooves left by the active components will appear, which is not conducive to the dispersion of the active components.

[0016] This invention utilizes a two-step preparation process. During the impregnation step, the loading of specific additives, particularly a sodium / potassium alkali metal-promoting silver additive, compensates for the defects of the alumina spherical support during catalyst preparation, thus facilitating the uniform dispersion of the platinum and palladium active components. The use of a spraying method to coat the platinum and palladium noble metal solution onto the support allows for rapid drying, ensuring that the active components remain on the support surface to the maximum extent possible while interacting with the additives. The catalyst prepared by this invention significantly enhances activity, achieving high activity even with relatively low noble metal loadings.

[0017] Preferably, in step 1), the alkali metal salt is a sodium salt and / or a potassium salt, more preferably sodium carbonate and / or potassium carbonate;

[0018] And / or, based on the weight of the spherical carrier, the amount of the alkali metal salt is 0.5% to 1%.

[0019] Preferably, in step 1), the soluble transition metal salt is selected from at least one of cerium salt, zirconium salt, magnesium salt, iron salt, and nickel salt, and more preferably from at least one of cerium carbonate, zirconium carbonate, magnesium carbonate, iron carbonate, and nickel carbonate.

[0020] And / or, based on the weight of the spherical carrier, the amount of the soluble transition metal salt is 1% to 5%.

[0021] Preferably, in step 1), the solution containing soluble ruthenium salt and / or soluble silver salt is a ruthenium trichloride solution, a ruthenium nitrite nitrate solution, or a silver nitrate solution;

[0022] And / or, based on the weight of the spherical carrier, the amount of the soluble ruthenium salt and / or soluble silver salt is 1% to 5% (when only one of the soluble ruthenium salt and soluble silver salt is contained, it is the amount of the soluble ruthenium salt or soluble silver salt; when both soluble ruthenium salt and soluble silver salt are contained, it is the total amount of both).

[0023] And / or, in the solution containing soluble ruthenium salt and / or soluble silver salt, the concentration of soluble ruthenium salt and / or soluble silver salt is 0.5 wt% to 5 wt%. In this invention, the soluble ruthenium salt and / or soluble silver salt must first be dissolved in water to form a solution before being added to the reaction system.

[0024] Preferably, in step 1), the immersion time is 60 min to 120 min;

[0025] And / or, the solvent is removed by heat treatment at 120°C to 150°C.

[0026] Preferably, in step 1), the high-temperature calcination temperature is 400–650°C, more preferably 550–600°C;

[0027] In step 1), the high-temperature roasting time is 2h to 5h.

[0028] Preferably, in step 2), the rotational speed of the coating machine is 6-20 r / min, and the temperature is room temperature to 60℃;

[0029] And / or, the drying temperature is 100–150°C.

[0030] Preferably, in step 2), the amount of noble metal elements (i.e., platinum and palladium) sprayed onto the surface of the catalyst precursor is 0.8 to 1.2 g / kg, based on the weight of the spherical carrier.

[0031] Preferably, in step 2), the mass ratio of platinum to palladium in the solution containing the soluble platinum compound and / or the soluble palladium compound is 1.8–2.2:1. Studies have found that the deoxygenation effect is better at the above-mentioned mass ratio of platinum to palladium.

[0032] Preferably, in step 3), the reduction activation is liquid-phase reduction activation or gas-phase reduction activation;

[0033] When liquid-phase reduction activation is used, the reducing agent is hydrazine hydrate or sodium borohydride, and the concentration of the reducing agent is 1 mol / L-10 mol / L;

[0034] When gas-phase reduction activation is used, the reducing agent is hydrogen or a hydrogen-containing atmosphere, and the reduction temperature is 500–650℃.

[0035] The present invention also provides a deoxygenation catalyst, which is prepared by the above-described preparation method.

[0036] This invention also provides the application of the above-mentioned deoxygenation catalyst or the deoxygenation catalyst prepared by the above-mentioned preparation method in hydrogen deoxygenation. This invention focuses on the removal of oxygen from hydrogen. Under conditions of an inlet oxygen concentration of 500-5000 ppm and a reaction temperature of 90°C, a purification effect of less than 1 ppm of oxygen concentration at the outlet can be achieved.

[0037] The beneficial effects of the present invention are at least as follows:

[0038] 1) The deoxygenation catalyst provided by the present invention, in the impregnation step, by loading specific additives, especially the use of sodium / potassium alkali metal promoted silver additives, makes up for the defects of the alumina spherical support in the catalyst preparation process, which is more conducive to the uniform dispersion of the platinum and palladium active components in the subsequent process.

[0039] 2) The deoxygenation catalyst provided by the present invention uses a spraying method to spray platinum and palladium noble metal solutions onto a support, which can make the support dry quickly, so that the active components can remain on the surface of the support to the maximum extent while reacting with the additives.

[0040] 3) The deoxygenation catalyst provided by this invention significantly improves the activity. Under the condition of a noble metal loading of no more than 1.2‰ (wt), it can eliminate oxygen in hydrogen at room temperature to achieve an outlet oxygen concentration of less than 1ppm, which satisfies the requirement of high activity under a low noble metal loading.

[0041] 4) The deoxygenation catalyst provided by the present invention preferably has a platinum to palladium mass ratio of 1.8 to 2.2:1, which can significantly improve the deoxygenation activity. Detailed Implementation

[0042] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions in the embodiments of this invention are described clearly and completely below. These embodiments are used to illustrate the invention but are not intended to limit its scope. Where specific techniques or conditions are not specified in the embodiments, they should be performed in accordance with the techniques or conditions described in the literature in the field, or in accordance with the product manual.

[0043] Example 1

[0044] Example 1 provides a deoxygenation catalyst, prepared by the following method:

[0045] 1) In the impregnation process, at room temperature, dissolve 0.5g potassium carbonate, 1.0g cerium nitrate, and 1.0g zirconium nitrate in 40ml deionized water, stir for 10min, and then add nitric acid dropwise until the solution pH = 1.5. Add 1g of nitrosyl ruthenium nitrate solution (2wt% concentration) to this solution and stir until ready for use. Weigh 100g of [amount missing] with a diameter of [missing information]. The alumina spherical support was mixed into the above solution and impregnated for 60 min, then dried at 120 °C to remove moisture, and calcined at 600 °C for 2 h to obtain the catalyst precursor for later use.

[0046] 2) In the spraying process, the above-mentioned catalyst precursor is placed in a coating machine (the coating machine is from Nanjing Huaiteng Machinery Technology Co., Ltd., BY-600), the rotation speed is adjusted to 10 r / min, and the hot air temperature is 60℃. 20 mL of chloroplatinic acid solution (containing 0.08 g of platinum element) is sprayed onto the surface of the catalyst precursor with a spray gun, and dried at 120℃ for later use.

[0047] 3) The activation method is gas phase reduction. The above catalyst is placed in the reactor, purged with nitrogen, and then pure hydrogen is introduced. The temperature is increased to 600℃ in 1.5 hours and held for 2 hours. The catalyst is obtained by cooling and is designated as catalyst #1.

[0048] Example 2

[0049] In Example 2, 0.5g potassium carbonate, 1.0g cerium nitrate, and 1.0g zirconium nitrate were replaced with 1.0g potassium carbonate, 2.0g cerium nitrate, and 2.0g zirconium nitrate. The remaining operations were the same as in Example 1. After reduction, a catalyst was obtained, which was designated as catalyst #2.

[0050] Example 3

[0051] In Example 3, 0.5g potassium carbonate, 1.0g cerium nitrate, and 1.0g zirconium nitrate were replaced with 1.0g sodium carbonate, 5.0g magnesium nitrate, 5.0g ferric nitrate, and 5.0g nickel nitrate. The remaining operations were the same as in Example 1. After reduction, a catalyst was obtained, which was designated as catalyst #3.

[0052] Example 4

[0053] In Example 4, activation was performed using liquid-phase reduction, with the remaining operations identical to those in Example 1. The catalyst was placed in an aqueous solution (5.0 mol / L) containing sodium borohydride for reduction, maintaining the temperature at 70°C. After 0.5 hours of reduction, the catalyst was removed, washed three times with deionized water, and dried to obtain the catalyst, designated as Catalyst #4.

[0054] Example 5

[0055] In Example 5, the heating and drying temperature in the impregnation process was adjusted from 120°C to 150°C, the calcination temperature was adjusted from 600°C to 450°C, the drying temperature in the spraying process was adjusted from 120°C to 150°C, and the temperature rise in the activation process was adjusted from 1.5h to 500°C. The remaining operations were the same as in Example 1. After reduction, a catalyst was obtained, which was designated as Catalyst No. 5.

[0056] Example 6

[0057] In Example 6, 20 mL of chloroplatinic acid solution containing 0.08 g of platinum (containing 0.08 g of platinum element) was replaced with 20 mL of platinum nitrate solution (containing 0.10 g of platinum element). The remaining operations were the same as in Example 1. After reduction, the catalyst was obtained and designated as catalyst #6.

[0058] Example 7

[0059] In Example 7, 20 mL of chloroplatinic acid solution (containing 0.08 g of platinum) was replaced with 20 mL of platinum nitrate solution (containing 0.12 g of platinum). The remaining operations were the same as in Example 1. After reduction, the catalyst was obtained and designated as catalyst #7.

[0060] Example 8

[0061] In Example 8, 20 mL of chloroplatinic acid solution (containing 0.08 g of platinum) was replaced with 20 mL of a mixed solution of platinum nitrate and palladium nitrate (containing 0.08 g of platinum and 0.04 g of palladium). The remaining operations were the same as in Example 1. After reduction, the catalyst was obtained and designated as catalyst #7.

[0062] Example 9

[0063] In Example 9, 20 mL of chloroplatinic acid solution (containing 0.08 g of platinum) was replaced with 20 mL of a mixed solution of platinum nitrate and palladium nitrate (containing 0.04 g of platinum and 0.08 g of palladium). The remaining operations were the same as in Example 1. After reduction, the catalyst was obtained and designated as catalyst #9.

[0064] Experimental Example 1

[0065] The deoxygenation performance of catalysts 1# to 9# prepared above was evaluated. The inlet gas composition consisted of oxygen concentration of 1000–1300 ppm (fluctuating), water content of 1000 ppm, and the remainder being hydrogen. The gas space velocity (GHSV) was 10000 h⁻¹. -1 The reaction temperature was 80℃. The specific results are shown in Table 1 below:

[0066] Table 1

[0067] 1# 0.92～0.98 6# 0.65～0.73 2# 0.89～1.00 7# 0.35～0.41 3# 3.21～3.45 8# 0.13～0.21 4# 4.54～4.88 9# 0.24～0.26 5# 0.88～0.95

[0068] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing a deoxygenation catalyst, characterized in that, Includes the following steps: 1) Impregnation: Dissolve alkali metal salts and soluble transition metal salts in water, adjust the pH to 1~2, then add a solution containing soluble ruthenium salts and / or soluble silver salts, mix evenly, impregnate the spherical support in it, then remove the solvent, and calcine at high temperature to obtain the catalyst support; 2) Spraying: The catalyst support is placed in a coating machine, and a solution containing soluble platinum compound and / or soluble palladium compound is uniformly sprayed onto the surface of the catalyst precursor under rotation. After drying, it is ready for use. 3) The catalyst dried in step 2) is then reduced and activated to obtain the final product; The spherical carrier is spherical alumina or spheres with alumina as the main component, and the particle size of the spherical carrier is 3 mm or more; In step 1), the soluble transition metal salt is selected from at least one of cerium salt, zirconium salt, magnesium salt, iron salt, and nickel salt; In step 2), the amount of noble metal elements sprayed onto the surface of the catalyst precursor is 0.8~1.2 g / kg, based on the weight of the spherical carrier.

2. The method for preparing a deoxygenation catalyst according to claim 1, characterized in that, In step 1), the alkali metal salt is a sodium salt and / or a potassium salt; And / or, based on the weight of the spherical carrier, the amount of the alkali metal salt is 0.5% to 1%.

3. The method for preparing a deoxygenation catalyst according to claim 2, characterized in that, The alkali metal salt is sodium carbonate and / or potassium carbonate.

4. The method for preparing a deoxygenation catalyst according to claim 1, characterized in that, In step 1), the amount of the soluble transition metal salt is 1% to 5% based on the weight of the spherical carrier.

5. The method for preparing a deoxygenation catalyst according to claim 1, characterized in that, In step 1), the solution containing soluble ruthenium salt and / or soluble silver salt is a ruthenium trichloride solution, a ruthenium nitrite nitrate solution, or a silver nitrate solution; And / or, based on the weight of the spherical carrier, the amount of the soluble ruthenium salt and / or soluble silver salt is 1% to 5%.

6. The method for preparing a deoxygenation catalyst according to claim 1, characterized in that, In step 1), the soaking time is 60 min to 120 min; And / or, the solvent is removed by heat treatment at 120°C to 150°C.

7. The method for preparing a deoxygenation catalyst according to claim 1, characterized in that, In step 2), the mass ratio of platinum to palladium in the solution containing soluble platinum compound and / or soluble palladium compound is 1.8~2.2:

1.

8. A deoxygenation catalyst, characterized in that, It is prepared by the preparation method according to any one of claims 1-7.

9. The application of the deoxygenation catalyst according to claim 8 or the deoxygenation catalyst prepared by any one of claims 1-7 in hydrogen deoxygenation.