A method for removing carbon oxides from hydrogen

Abstract

The present application belongs to the hydrogen purification technical field, and relates to a method for removing carbon oxides from hydrogen. The hydrogen-rich gas containing carbon oxides is subjected to a contact reaction with a nickel catalyst, wherein the nickel catalyst comprises a carrier alumina and an active component nickel dispersed thereon; the carrier alumina is prepared by using a rotary strengthening device, including the following steps: using a liquid pump to pump an aluminum sulfate solution and an aluminum hydroxide-sodium hydroxide mixed solution into a rotary strengthening reactor to form a slurry; spraying the slurry into the inside of a wire mesh packing through a solution mixing distributor, and shearing the slurry into small units by rotating the wire mesh packing; making the small units pass through the outlet of the rotary strengthening reactor into a crystallization kettle to perform crystallization to obtain crystallized materials, and performing calcination after filtration, washing and drying to obtain the alumina carrier. The carrier alumina used in the present application has high reactivity in the application of removing trace carbon oxides from hydrogen.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of hydrogen purification, and particularly relates to a method for removing carbon oxides from hydrogen. BACKGROUND

[0002] Methanation, as the simplest reaction in Fischer-Tropsch synthesis, is mainly applied in the fields of ethylene industry, ammonia synthesis, hydrogen purification and coal gasification, aiming to convert COx into methane or remove impurities COx in raw gas to achieve the purpose of purification. Natural gas is one of fossil energies, mainly applied in the fields of chemical industry and fuel, and the main component methane can be obtained by catalytic conversion of synthesis gas (COx, H2). As the simplest Fischer-Tropsch synthesis reaction, methanation has the advantages of high calorific value, high conversion rate, single product and good economic benefits.

[0003] Current industrial methanation catalysts mainly consist of Ni, Ru active components, additives and carriers, and are prepared by a traditional impregnation method. The main process is to immerse the carrier in a solution containing active components, contact for a period of time, and then remove the remaining liquid by filtration, evaporation and other methods, and the active components are loaded on the surface of the carrier in the form of ion or compound microcrystals, and then the final catalyst product is prepared by drying, calcination and other activation processes. For example, CN103055874A discloses a methanation catalyst, and the preparation steps are to immerse an aqueous solution containing nickel and additive in an equal amount on an alumina carrier, and then dry and calcine. CN102319574A also discloses a methanation catalyst, and nickel is loaded on ceria modified alumina by impregnation method. The main features of the impregnation method are: (1) the carrier with a certain shape and size is used, and no further catalyst molding operation is needed; (2) the impregnation method can load one or several active components on the carrier; (3) the pore structure of the carrier basically determines the pore structure and specific surface area of the prepared catalyst. However, it is worth noting that in order to obtain a high-activity catalyst, multiple impregnation and calcination operations are often required, which causes large energy consumption and carbon emission, and does not meet the current energy saving and carbon reduction requirements.

[0004] CN106492864B discloses a CO methanation catalyst with carbon carrier, which can realize a large nickel loading at one time. However, the preparation process of the catalyst needs pyrolysis under high-temperature and oxygen-free conditions, which produces a large amount of hydrocarbon waste gas and tar, and the pyrolysis temperature is high. SUMMARY

[0005] In order to solve the problems in the prior art, the present application provides a method for removing carbon oxides from hydrogen, and the carrier alumina used can prepare a high-content nickel catalyst by one-time impregnation, and has high reaction activity in the application of removing trace carbon oxides from hydrogen.

[0006] To achieve the above object, the present application provides a method for removing carbon oxides from hydrogen, which comprises contacting a hydrogen-rich gas containing carbon oxides with a nickel catalyst comprising a support alumina and an active component nickel dispersed thereon;

[0007] The support alumina is prepared by using a rotating strengthening device, which comprises a rotating strengthening reactor, at least two liquid pumps, a crystallization kettle and a motor.

[0008] The rotating strengthening reactor comprises a rotating strengthening reactor shell, a wire mesh packing and a solution mixing distributor, the wire mesh packing is located inside the rotating strengthening reactor shell and forms a space on the inner side thereof, the solution mixing distributor is arranged in the space, and the motor is connected with the wire mesh packing.

[0009] The liquid pump is provided with a liquid pump discharge pipeline, the rotating strengthening reactor shell is provided with a rotating strengthening reactor inlet and a rotating strengthening reactor outlet, the liquid pump discharge pipeline is connected with the solution mixing distributor through the rotating strengthening reactor inlet, and the rotating strengthening reactor outlet is connected with the crystallization kettle.

[0010] The method comprises the following steps:

[0011] (1) An aluminum sulfate solution and an aluminum hydroxide-sodium hydroxide mixed solution are jointly pumped into the rotating strengthening reactor from the rotating strengthening reactor inlet by using a liquid pump to form a slurry;

[0012] (2) The slurry is sprayed into the inner side of the wire mesh packing through the solution mixing distributor, and the wire mesh packing is rotated under the driving of the motor to shear the slurry into small units;

[0013] (3) The small units obtained in step (2) are introduced into the crystallization kettle through the rotating strengthening reactor outlet to perform crystallization to obtain a crystallized material, and the crystallized material is filtered, washed, dried and then calcined to obtain the alumina support.

[0014] In the present application, the preparation method of the support alumina is performed by using the rotating strengthening impregnation device as shown in Figure 1 In the strengthening hydrolysis process, the reaction liquid is dispersed into fine droplets and liquid membranes on the wire mesh rotating at high speed, the microenvironment of the precipitation reaction is more uniform, and thus the crystal seeds with uniform size are obtained. After crystallization and calcination, the support alumina with stable structure and performance is obtained.

[0015] According to the present application, preferably, the concentration of the aluminum sulfate solution is 0.5-2 mol / L.

[0016] According to the present application, preferably, the concentration of aluminum hydroxide in the aluminum hydroxide-sodium hydroxide mixed solution is 0.5-1 mol / L, and the concentration of sodium hydroxide is 1-1.5 mol / L.

[0017] According to the present application, preferably, the flow rate ratio of the aluminum sulfate solution to the aluminum hydroxide-sodium hydroxide mixed solution is 1:(0.5-2).

[0018] According to the present application, preferably, in step (2), the rotating speed of the wire mesh filler is 2800-3200 rpm.

[0019] According to the present application, preferably, the crystallization conditions include a temperature of 60-100°C and a time of 2-24 h.

[0020] According to the present application, preferably, the drying conditions include a temperature of 60-120°C and a time of 4-12 h.

[0021] According to the present application, preferably, the calcination conditions include a temperature of 400-800°C and a time of 4-8 h.

[0022] According to the present application, preferably, the alumina carrier has the following characteristics: a specific surface area of 300-800 m 2 / g, preferably 400-700 m 2 / g, and an average pore size of 10-40 nm, preferably 20-35 nm.

[0023] According to the present application, preferably, the preparation method of the nickel catalyst comprises the following steps:

[0024] a) immersing the carrier alumina in a nickel salt solution by an excess immersion method to obtain the carrier alumina immersed with the nickel salt solution;

[0025] b) directly drying and calcining the carrier alumina immersed with the nickel salt solution obtained in step a) to obtain the nickel catalyst.

[0026] According to the present application, preferably, in step a), the nickel salt solution is a water-soluble nickel salt solution, preferably at least one of a nickel nitrate solution, a nickel carbonate solution and a nickel sulfate solution.

[0027] Further preferably, the concentration of the nickel salt solution is 3-5 mol / L, and the immersion time is 30-120 min.

[0028] According to the present application, preferably, in step b), the drying conditions include a temperature of 110-130°C and a time of 4-12 h, and the calcination conditions include a temperature of 600-800°C and a time of 4-8 h.

[0029] According to the present application, preferably, the content of the active component nickel is 30-70wt%, preferably 40-60wt%, and the content of the carrier alumina is 30-70wt%, preferably 40-60wt%.

[0030] According to the present application, preferably, the conditions of the contact reaction include: the reaction temperature is 150-180℃, the reaction pressure is 1-4MPa, the gas space velocity is 1000-3000h -1 , the carbon oxide concentration in the inlet gas before the reaction is less than 3000ppm, and the carbon oxide concentration in the gas after the reaction is less than 1ppm.

[0031] The present application adopts reinforced hydrolysis to prepare the carrier alumina, and the carrier alumina can be used to prepare the nickel catalyst with high content through one-time impregnation, and the nickel catalyst has high reaction activity when used in the application of removing trace carbon oxides in hydrogen.

[0032] Other features and advantages of the present application will be described in detail in the following specific embodiment part. BRIEF DESCRIPTION OF DRAWINGS

[0033] The exemplary embodiments of the present application will be described in more detail by combining the accompanying drawings.

[0034] Figure 1 It is a schematic diagram of the rotating reinforcement device.

[0035] Explanation of reference signs

[0036] 1-1, aluminum sulfate solution; 1-2, aluminum hydroxide-sodium hydroxide mixed solution; 1-3, 1-4, liquid pump; 1-5, solution mixing distributor; 1-6, wire mesh packing; 1-7, rotating reinforcement reaction device shell; 1-8, reactant outlet; 1-9, crystallization kettle; 1-10, motor. DETAILED DESCRIPTION

[0037] The specific embodiments of the present application will be described in detail below. It should be understood that the specific embodiments described herein are only used to illustrate and explain the present application, and are not used to limit the present application.

[0038] The present application will be further described below in combination with examples, but the scope of the present application is not limited to these examples.

[0039] The test instruments and test conditions used in the examples are as follows:

[0040] The specific surface area (BET) and average pore size of the nickel catalyst are measured by N2 adsorption-desorption method.

[0041] The sources of raw materials used in the examples are as follows:

[0042] All other reagents used were commercially available and of analytical grade.

[0043] Example 1

[0044] Carrier alumina: Prepare a 0.5 mol / L aqueous solution of aluminum sulfate, a mixture of aluminum hydroxide and sodium hydroxide at 1 mol / and 1 mol / respectively, and the flow ratio of aluminum sulfate solution to aluminum hydroxide-sodium hydroxide mixed solution is 1:0.7. Turn on the motor to drive the rotating filler at a speed of 3000 rpm. The two liquids are pumped into the liquid distributor through a horizontal flow pump to mix and spray into the enhanced reactor. Under the shearing action of the rotating filler, the mixed reaction liquid is sheared into tiny suspension droplets and finally enters the crystallization kettle from the bottom of the enhanced reactor and crystallizes at 80°C for 20 hours. After crystallization, it is filtered and washed with deionized water, and then dried at 80°C for 20 hours. Finally, the dried powder is calcined in an air atmosphere at 400°C to obtain an alumina carrier. The specific surface area of ​​the alumina carrier obtained by the enhanced hydrolysis method is 698m 2 / g, and the average pore diameter is 21nm.

[0045] Nickel catalyst: The above-mentioned carrier alumina was immersed in a 4 mol / L nickel nitrate aqueous solution, filtered after 30 min, dried at 120°C, and calcined at 400°C to obtain a nickel catalyst with a NiO loading of 55%, which was designated as A-1.

[0046] Example 2

[0047] Carrier alumina: Prepare a 2 mol / L aqueous solution of aluminum sulfate, a mixture of 0.5 mol / and 1.5 mol / of aluminum hydroxide and sodium hydroxide respectively, and the flow ratio of the aluminum sulfate solution to the aluminum hydroxide-sodium hydroxide mixed solution is 1:2. Turn on the motor to drive the rotating filler at a speed of 3000 rpm. The two liquids are pumped into the liquid distributor through a horizontal flow pump and mixed and sprayed into the enhanced reactor. Under the shearing action of the rotating filler, the mixed reaction liquid is sheared into tiny suspension droplets, and finally enters the crystallization kettle from the bottom of the enhanced reactor and crystallizes at 80°C for 20 hours. After crystallization, it is filtered and washed with deionized water, and then dried at 80°C for 20 hours. Finally, the dried powder is calcined in an air atmosphere at 500°C to obtain an alumina carrier. The specific surface area of ​​the alumina carrier obtained by the enhanced hydrolysis method is 412m 2 / g, and the average pore diameter is 32nm.

[0048] Nickel catalyst: The above-mentioned carrier alumina was immersed in a 4 mol / L nickel nitrate aqueous solution, filtered after 30 min, dried at 120°C, and calcined at 400°C to obtain a nickel catalyst with a NiO loading of 48%, which was designated as A-2.

[0049] Example 3

[0050] Carrier alumina: Prepare a 1 mol / L aqueous solution of aluminum sulfate, a mixture of 0.5 mol / and 1.5 mol / of aluminum hydroxide and sodium hydroxide respectively, and the flow ratio of the aluminum sulfate solution to the aluminum hydroxide-sodium hydroxide mixed solution is 1:1.2. Turn on the motor to drive the rotating filler at a speed of 3000 rpm. The two liquids are pumped into the liquid distributor through a horizontal flow pump and mixed and sprayed into the enhanced reactor. Under the shearing action of the rotating filler, the mixed reaction liquid is sheared into tiny suspension droplets, and finally enters the crystallization kettle from the bottom of the enhanced reactor and crystallizes at 80°C for 20 hours. After crystallization, it is filtered and washed with deionized water, and then dried at 80°C for 20 hours. Finally, the dried powder is calcined in an air atmosphere at 800°C to obtain an alumina carrier. The specific surface area of ​​the alumina carrier obtained by the enhanced hydrolysis method is 581m 2 / g, and the average pore diameter is 23nm.

[0051] Nickel catalyst: The above-mentioned carrier alumina was immersed in a 4 mol / L nickel nitrate aqueous solution, filtered after 30 min, dried at 120°C, and calcined at 450°C to obtain a nickel catalyst with a NiO loading of 51%, which was designated as A-3.

[0052] Comparative Example 1

[0053] Commercial alumina carrier (Yinuokai JHZ-04) was used, with a BET specific surface area of ​​239m 2 / g, and the average pore diameter is 13nm.

[0054] The commercial alumina support was immersed in a 4 mol / L nickel nitrate aqueous solution, filtered after 30 min, dried at 120°C, and calcined at 450°C. After one impregnation, a nickel catalyst with a NiO loading of 19% was obtained, which was recorded as D-1.

[0055] Comparative Example 2

[0056] Commercial alumina carrier (Yinuokai JHZ-04) was used, with a BET specific surface area of ​​239m 2 / g, and the average pore diameter is 13nm.

[0057] The commercial alumina support was immersed in a 4 mol / L nickel nitrate aqueous solution, filtered after 30 min, dried at 120°C, and calcined at 450°C. After multiple impregnations, a nickel catalyst with a NiO loading of 43% was obtained, which was recorded as D-2.

[0058] Comparative Example 3

[0059] The carrier alumina was prepared by ordinary co-precipitation method: 1 mol / L aluminum sulfate aqueous solution, a mixture of 0.5 mol / and 1.5 mol / of aluminum hydroxide and sodium hydroxide respectively, the flow ratio of aluminum sulfate solution to aluminum hydroxide-sodium hydroxide mixed solution was 1:1.2, and they were added dropwise into the stirred reactor. The reaction precipitate was transferred to a crystallization kettle and crystallized at 80°C for 20 hours. After crystallization, it was filtered and washed with deionized water, and then dried at 80°C for 20 hours. Finally, the dried powder was calcined in an air atmosphere at 500°C to obtain an alumina carrier. The specific surface area of ​​the alumina carrier obtained by the enhanced hydrolysis method was measured by N2 adsorption and desorption method to be 406m 2 / g, and the average pore diameter is 13nm.

[0060] Nickel catalyst: The above-mentioned carrier alumina was immersed in a 4 mol / L nickel nitrate aqueous solution, filtered after 30 min, dried at 120°C, and calcined at 450°C. A nickel catalyst with a NiO loading of 21% was obtained through one impregnation, which was recorded as D-3.

[0061] Test Case

[0062] 10 ml of each catalyst from Examples 1-6 and Comparative Examples 1-2 was loaded into a stainless steel fixed-bed reactor. High-purity hydrogen was introduced at a flow rate of 300 ml / min and the temperature was raised to 450°C for catalyst reduction for 4 hours. High-purity nitrogen was then switched to a flow rate of 300 ml / min. When the temperature dropped to a predetermined value, feed gas was introduced. The CO content in the feed gas was 1000 ppm. Other conditions are listed in Table 1. The composition of the post-reaction gas was analyzed by gas chromatography using an FID detector.

[0063] Table 1

[0064]

[0065] As shown in Table 1, the alumina carrier prepared using the enhanced hydrolysis method can achieve a high nickel loading and high CO removal efficiency in a single impregnation operation. Compared with commercial alumina carriers and alumina carriers prepared by the conventional stirred precipitation method, the preparation steps are simplified and the loading capacity per single impregnation is significantly increased, effectively reducing the production cost of the catalyst and achieving the goals of energy conservation, emission reduction and carbon reduction.

[0066] While various embodiments of the present invention have been described above, the above description is intended to be illustrative, not exhaustive, and not limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments.

[0067] The endpoints of the ranges and any values disclosed herein are not limited to the precise values recited as exactly that endpoint point. The endpoints of the ranges and any values are understood to be approximate values. For ranges having an upper and lower limit, the range can be understood to include each integer within the defined range. The upper and lower limits of the range can independently be included in the range, or independently excluded from the range. The range can also be understood to include single values within the range, which can be the upper or lower limit of the range. For ranges having an upper and lower limit, the range can be understood to include each integer within the defined range. The upper and lower limits of the range can independently be included in the range, or independently excluded from the range. The range can also be understood to include single values within the range, which can be the upper or lower limit of the range.

Claims

1. A method for removing carbon oxides from hydrogen, characterized in that: The hydrogen-rich gas containing carbon oxides is contacted with a nickel catalyst for reaction, wherein the nickel catalyst comprises a carrier alumina and an active component nickel dispersed thereon; The carrier alumina is prepared by using a rotary strengthening device, which includes: a rotary strengthening reactor, at least two liquid pumps, a crystallization kettle and a motor; The rotary intensified reactor comprises a rotary intensified reaction device housing, a wire mesh filler, and a solution mixing and distributing device. The wire mesh filler is located inside the rotary intensified reaction device housing, and a certain space is formed inside the wire mesh filler. The solution mixing and distributing device is placed in the space. The motor is connected to the wire mesh filler. The liquid pump is provided with a liquid pump discharge pipeline, the rotary enhanced reaction device housing is provided with a rotary enhanced reactor inlet and a rotary enhanced reactor outlet, the liquid pump discharge pipeline is connected to the solution mixing distributor through the rotary enhanced reactor inlet, and the rotary enhanced reactor outlet is connected to the crystallization kettle; The steps include: (1) A liquid pump is used to pump the aluminum sulfate solution and the aluminum hydroxide-sodium hydroxide mixed solution into the rotary intensified reactor from the inlet of the rotary intensified reactor to form a suspension; (2) The suspension is sprayed into the inner side of the wire mesh filler through a solution mixing distributor, and the wire mesh filler is rotated under the drive of a motor to shear the suspension into small units; (3) The micro-units obtained in step (2) are passed through the outlet of the rotary intensified reactor into a crystallization kettle for crystallization to obtain a crystallized material. The crystallized material is filtered, washed, dried, and then calcined to obtain the alumina carrier.

2. The method for removing carbon oxides from hydrogen according to claim 1, wherein: The concentration of the aluminum sulfate solution is 0.5-2 mol / L; The aluminum hydroxide-sodium hydroxide mixed solution has an aluminum hydroxide concentration of 0.5-1 mol / L and a sodium hydroxide concentration of 1-1.5 mol / L; The flow ratio of the aluminum sulfate solution to the aluminum hydroxide-sodium hydroxide mixed solution is 1: (0.5~2).

3. The method for removing carbon oxides from hydrogen according to claim 1, wherein: In step (2), the mesh filler rotates at a speed of 2800-3200 rpm.

4. The method for removing carbon oxides from hydrogen according to claim 1, wherein: In step (3), the crystallization conditions include: temperature of 60-100°C and time of 2-24h; The drying conditions include: temperature of 60-120°C and time of 4-12 hours; The calcination conditions include: a temperature of 400-800° C. and a calcination time of 4-8 hours.

5. The method for removing carbon oxides from hydrogen according to claim 1, wherein: The alumina carrier has the following characteristics: a specific surface area of ​​300-800 m 2 / g, and the average pore size is 10~40nm.

6. The method for removing carbon oxides from hydrogen according to claim 5, wherein: The alumina carrier has the following characteristics: a specific surface area of ​​400-700 m 2 / g, and the average pore size is 20~35nm.

7. The method for removing carbon oxides from hydrogen according to any one of claims 1 to 6, wherein: The preparation method of the nickel catalyst comprises the following steps: a) impregnating the carrier alumina into a nickel salt solution by an over-impregnation method to obtain a carrier alumina impregnated with the nickel salt solution; b) directly drying and calcining the carrier alumina impregnated with the nickel salt solution obtained in step a) to obtain the nickel catalyst.

8. The method for removing carbon oxides from hydrogen according to claim 7, wherein: In step a), the nickel salt solution is a water-soluble nickel salt solution; The concentration of the nickel salt solution is 3-5 mol / L, and the immersion time is 30-120 min.

9. The method for removing carbon oxides from hydrogen according to claim 8, wherein: The nickel salt solution is at least one of a nickel nitrate solution, a nickel carbonate solution and a nickel sulfate solution.

10. The method for removing carbon oxides from hydrogen according to claim 7, wherein: In step b), the drying conditions include: a temperature of 110-130°C and a time of 4-12 hours; The calcination conditions include: temperature of 600-800°C and time of 4-8 hours.

11. The method for removing carbon oxides from hydrogen according to claim 7, wherein: The content of the active component nickel is 30-70 wt %, and the content of the carrier alumina is 30-70 wt %.

12. The method for removing carbon oxides from hydrogen according to claim 11, wherein: The content of the active component nickel is 40-60 wt %, and the content of the carrier alumina is 40-60 wt %.

13. The method for removing carbon oxides from hydrogen according to claim 1, wherein: The conditions for the contact reaction include: reaction temperature of 150-180°C, reaction pressure of 1-4 MPa, gas space velocity of 1000-3000 h -1 , the carbon oxide concentration in the inlet gas before the reaction is less than 3000ppm, and the carbon oxide concentration in the gas after the reaction is less than 1ppm.

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