A method for purifying hydrogen for fuel cells

Abstract

This invention provides a method for purifying hydrogen for fuel cells. The method includes: reducing a catalyst with hydrogen to obtain a reduction catalyst; treating carbon oxide impurities in the hydrogen for fuel cells with the reduction catalyst; the catalyst comprises an alumina support and a nickel compound and an auxiliary metal compound supported thereon, wherein, based on the weight of the catalyst, the nickel content is 5-50 wt% (elementally), and the auxiliary metal content is 0.01-10 wt% (elementally); the nickel dispersion in the reduction catalyst is 0.5-5%; and the nickel particle size is 10-100 nm. The catalyst of this invention is obtained by centrifugally spraying an impregnation solution onto a rotating alumina support, followed by drying and calcination. The catalyst of this invention has a smaller nickel particle size and nickel dispersion, and exhibits superior low-temperature catalytic activity in the purification of carbon oxides in hydrogen for fuel cells.

Description

Technical Field

[0001] This invention belongs to the field of hydrogen energy, and specifically relates to a method for purifying hydrogen for fuel cells. Background Technology

[0002] Hydrogen energy boasts advantages such as wide availability, high calorific value, cleanliness, and broad applications, making it an indispensable energy carrier for improving the energy structure and driving the energy revolution in the future. The development focus of the hydrogen energy industry has historically been on the transportation sector, primarily concentrating on the research and development of hydrogen fuel cell vehicles and the construction of hydrogen refueling stations. In the future, the application of hydrogen energy in rail transit will be another key focus.

[0003] Currently, China is the world's largest hydrogen producer, with an annual output of approximately 22 million tons, accounting for one-third of global hydrogen production. Large-scale hydrogen production is a mature technology globally and in China. However, it's worth noting that China's hydrogen currently mainly comes from coal-based hydrogen production or industrial by-products, including propane and ethane dehydrogenation, hydrogen from the chlor-alkali industry, and purge gas from coal-to-methanol production. Enterprises purify industrial hydrogen using pressure swing adsorption (PSA) technology to obtain general industrial-grade hydrogen. The table below shows the analysis results of industrial-grade hydrogen from a certain enterprise.

[0004]

[0005]

[0006] The analysis results in the table above show that carbon monoxide (CO) accounts for the highest proportion of impurities in industrial hydrogen exported from pressure swing adsorption (PSA) technology, followed by nitrogen (calculated as N2+Ar); the content of carbon dioxide (CO2) is extremely low. According to the national standard GB / T 37244 for hydrogen used in fuel cells, the carbon monoxide (CO) content in the hydrogen needs to be further reduced to meet the standards for hydrogen used in fuel cells.

[0007] Currently, the process for further purifying industrial hydrogen to produce hydrogen for fuel cells still primarily relies on Pressure Swing Adsorption (PSA) technology. PSA is a gas separation technology that uses pressure changes to adsorb and regenerate different components in a gas using an adsorbent. PSA consists of several adsorption tanks, each filled with adsorbent in the same order. It utilizes the characteristic that the adsorbent has a weak adsorption capacity for hydrogen components in the mixed gas but a strong adsorption capacity for other components, adsorbing impurities from the gas passing through the bed to obtain high-purity hydrogen. During adsorbent regeneration, impurities adsorbed on the adsorbent are desorbed and discharged into the desorbed gas system through processes such as reverse desorption. In a typical PSA hydrogen purification process, the gas from the feed enters the adsorption tank from bottom to top, passing through adsorbents with different functions in sequence. Impurities are adsorbed, and the hydrogen purity increases progressively, finally reaching the top as high-purity hydrogen. Generally, the adsorption tank consists of the following layers from bottom to top: the first layer is activated alumina adsorbent, used to remove moisture; the second layer is special silica gel adsorbent, used to remove moisture and carbon dioxide (CO2); the third layer is special activated carbon adsorbent, used to powerfully remove carbon dioxide (CO2); the fourth layer is a metal complex adsorbent supported on activated carbon, used to remove carbon monoxide (CO); and the fifth layer is 5A molecular sieve, used to finely remove methane (CH4), nitrogen (N2), and carbon monoxide (CO) from hydrogen to ensure the final purity of the product.

[0008] Although the Pressure Swing Adsorption (PSA) technology is relatively mature, its operation is cumbersome and complex, and the adsorbent requires frequent desorption and regeneration. Furthermore, the hydrogen purity in the desorbed gas produced during adsorbent regeneration remains relatively high. In fuel cell hydrogen production, the desorbed gas volume typically accounts for more than 20% of the industrial hydrogen feed from PSA. Because the desorbed gas pressure in PSA is atmospheric pressure, despite the high hydrogen purity, the extremely low pressure makes it difficult to utilize, and it can only be released as low-pressure flare gas to the flare system, resulting in significant waste and underutilization of high-value hydrogen. Due to the stringent requirements for impurity content in fuel cell hydrogen production, the hydrogen yield from PSA is generally low, typically 80% or even lower, to ensure adequate impurity removal.

[0009] CN 113929056 A discloses an integrated adsorption separation device for purifying hydrogen. The device is filled with a large number of different types of adsorbents, and frequent adsorption-desorption operations are required during operation, making the operation cumbersome and complex.

[0010] CN 111377404 B discloses an apparatus and operating method for producing high-purity hydrogen using a PSA process. The PSA 10-2-4 process is employed, with an adsorbent loading of 41 tons. During operation, the product gas and desorption gas yields 49000 Nm³ and 49000 Nm³, respectively. 3 / h and 25035Nm 3 / h. The hydrogen yield is only 66%, resulting in a significant waste of hydrogen resources.

[0011] CN 1512615 A ​​discloses a technology for converting carbon monoxide (CO) in hydrogen into carbon dioxide (CO2) using a catalyst, and further removing carbon dioxide (CO2) to produce hydrogen for fuel cells. Specifically, it utilizes the water-gas shift reaction of carbon monoxide (CO), where hydrogen (H2) and carbon dioxide (CO2) are obtained through the reaction of carbon monoxide (CO) with water (H2O). Although carbon monoxide (CO) is removed, carbon dioxide (CO2) and H2O are also added, requiring additional subsequent separation steps.

[0012] In summary, developing a hydrogen purification method for fuel cells with high hydrogen utilization and simple operation, which reduces the content of carbon monoxide (CO), the main impurity in industrial hydrogen, to less than 0.2 ppm, meets the requirements of the national standard GB / T37244-2018 for fuel cell hydrogen, and has significant application value. Summary of the Invention

[0013] To address the problems in the existing technology, this invention proposes a method for purifying hydrogen for fuel cells. The catalyst used in this purification method is prepared using a rotary enhanced impregnation device. The prepared catalyst removes trace amounts of carbon oxides from hydrogen through a hydrogenation reaction under gas-solid two-phase conditions, reducing the carbon oxides in the hydrogen to below 0.2 ppm, thus obtaining hydrogen for fuel cells that meets the requirements of the national standard GB / T 37244-2018 for fuel cells.

[0014] To achieve the above objectives, the present invention provides a method for purifying hydrogen for fuel cells, the method comprising the following steps:

[0015] (1) Hydrogen reduction: The catalyst is reduced in a hydrogen atmosphere to obtain a reduced catalyst;

[0016] (2) Hydrogen purification: treating carbon oxide impurities in hydrogen for fuel cells with the reduction catalyst described above;

[0017] The catalyst comprises an alumina support and a nickel compound and an auxiliary metal compound supported thereon, wherein, based on the weight of the catalyst, the nickel content is 5 to 50 wt%, preferably 10 to 45 wt%, and the auxiliary metal content is 0.01 to 10 wt%, preferably 0.1 to 1.5 wt%, based on the elemental content of the catalyst.

[0018] In the reduction catalyst, the nickel dispersion is 0.5-5%, preferably 1.0-2.5%; the nickel particle size is 10-100 nm, preferably 20-65 nm.

[0019] The effects of this invention are:

[0020] (1) The nickel component in the catalyst for purifying hydrogen for fuel cells has high dispersion and small average particle size, and exhibits superior low-temperature catalytic activity when purifying carbon oxides in hydrogen for fuel cells.

[0021] (2) The method for preparing the catalyst for purifying hydrogen in fuel cells according to the present invention utilizes rotary impregnation technology, using a rotary enhanced impregnation device as the catalyst preparation equipment. The impregnation liquid located inside the rotating packing forms liquid mist and droplets under centrifugal force, which are sprayed onto the alumina support in the rotating support ring on the outside at extremely high speed. The highly dispersed fine droplets, the extremely high initial velocity, and the constantly renewed phase interface can effectively improve the diffusion and permeation rate of the impregnation liquid in the pores of the alumina support, promote the uniform adsorption of active components on the surface of the alumina support, and at the same time greatly shorten the impregnation time.

[0022] (3) The method for purifying hydrogen for fuel cells in this invention is simple to operate. It only requires one catalytic reaction to purify carbon oxide impurities in hydrogen and has a high hydrogen yield. The prepared hydrogen meets the standards for hydrogen for fuel cells.

[0023] Other features and advantages of the present invention will be described in detail in the following detailed description section. Attached Figure Description

[0024] The above and other objects, features and advantages of the present invention will become more apparent from the more detailed description of exemplary embodiments of the invention in conjunction with the accompanying drawings, wherein the same reference numerals generally represent the same components in the exemplary embodiments of the invention.

[0025] Figure 1 This is a schematic diagram of the catalyst preparation apparatus used in the hydrogen purification method for fuel cells provided by the present invention.

[0026] Explanation of reference numerals in the attached figures:

[0027] 101-First motor; 102-Second motor; 103-Rotating reinforced packing bed; 104-Liquid storage tank; 105-Liquid pump; 106-Liquid distributor; 107-Rotating packing; 108-Carrier ring; 109-Carrier particles; 110-Impregnating liquid inlet; 111-Impregnating liquid outlet. Detailed Implementation

[0028] Preferred embodiments of the invention will now be described in more detail. While preferred embodiments of the invention are described below, it should be understood that the invention can be implemented in various forms and should not be limited to the embodiments set forth herein.

[0029] In this disclosure, unless otherwise stated, directional terms such as "upper" and "lower" generally refer to the upper and lower positions of the device in its normal operating state, for example, as shown in the reference. Figure 1 In the drawing orientation, "inner" and "outer" refer to their relative to the outline of the device. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first," "second," or "third" may explicitly or implicitly include one or more of that feature. In the description of this disclosure, "a plurality of" means two or more, unless otherwise explicitly specified.

[0030] This invention provides a method for purifying hydrogen for fuel cells, the method comprising the following steps:

[0031] (1) Hydrogen reduction: The catalyst is reduced in a hydrogen atmosphere to obtain a reduced catalyst;

[0032] (2) Hydrogen purification: Carbon oxide impurities in hydrogen used in fuel cells are treated with a reduction catalyst;

[0033] The catalyst comprises an alumina support and a nickel compound and an auxiliary metal compound supported thereon, wherein, based on the weight of the catalyst, the nickel content is 5 to 50 wt%, preferably 10 to 45 wt%, and the auxiliary metal content is 0.01 to 10 wt%, preferably 0.1 to 1.5 wt%, based on the elemental content of the catalyst.

[0034] In the reduction catalyst, the nickel dispersion is 0.5-5%, preferably 1.0-2.5%; the nickel particle size is 10-100 nm, preferably 20-65 nm.

[0035] According to the present invention, the nickel compound is nickel oxide; the auxiliary metal compound is at least one of oxides of magnesium, calcium, lanthanum, barium, and cerium.

[0036] According to the present invention, the specific surface area of ​​the alumina carrier is 100-300 m². 2 / g, preferably 140-250m 2 / g. Pore volume is 0.5~1.5m. 3 / g, preferably 0.7~1.2m 3 / g.

[0037] The alumina carrier used in this invention can be a commercially available molded alumina carrier, or it can be a commercially available alumina carrier that has been processed to obtain an alumina carrier, as long as the obtained alumina carrier meets the above-mentioned specific surface area and pore volume requirements. According to the preferred embodiment of this invention, the molded alumina carrier produced by Beijing Chemical Research Institute is the best.

[0038] According to the present invention, the catalyst described above is prepared by a method comprising the following steps:

[0039] A salt solution containing nickel and additive metals is used as the impregnation liquid. The alumina support is placed in the support ring 108. The impregnation liquid is then centrifugally sprayed onto the rotating alumina support through a rotating packing 107. After that, the impregnated alumina support is dried and calcined to obtain the catalyst.

[0040] Preferably, the catalyst is prepared by a method comprising the following steps:

[0041] Step 1: Use a mixed salt solution containing metallic nickel salt and auxiliary metallic salt as the impregnation solution;

[0042] Step 2: Load the alumina carrier into the carrier ring 108, pump the impregnation liquid into the liquid distributor 106 in the center of the rotating packing 107, and spray it evenly into the inner side of the rotating packing 107 through the liquid distributor 106.

[0043] Step 3: The impregnation liquid inside the rotating packing 107 is centrifugally sprayed onto the alumina carrier in the outer rotating carrier ring 108 by the rotation of the rotating packing 107. Then the impregnated alumina carrier is dried and calcined.

[0044] Step 4: Optionally repeat the operations of Steps 2 and 3 at least once to obtain the catalyst.

[0045] According to the present invention, the metallic nickel salt is selected from at least one of nickel nitrate, nickel sulfate, and basic nickel carbonate.

[0046] The auxiliary metal salt is selected from at least one of magnesium, calcium, lanthanum, barium, and cerium metal salts, and preferably from at least one of magnesium, calcium, lanthanum, barium, and cerium nitrate, sulfate, or carbonate.

[0047] According to the present invention, the mass percentage concentration of metallic nickel in the mixed salt solution is 1-15%, preferably 5-15%. The mass percentage concentration of the auxiliary metal in the mixed salt solution is 0.01-5%, preferably 0.1-1%.

[0048] The specific surface area of ​​the alumina carrier is 100–300 m². 2 / g, preferably 140-250m 2 / g; pore volume is 0.5~1.5m 3 / g, preferably 0.7~1.2m 3 / g.

[0049] According to the present invention, preferably, the carrier ring 108 is a wire mesh carrier ring.

[0050] According to the present invention, preferably, the rotating packing 107 is a wire mesh or a cylindrical packing.

[0051] According to the present invention, preferably, the rotational speed of the rotating packing 107 is 1000 to 2000 rpm.

[0052] According to the present invention, preferably, the rotational speed of the carrier ring 108 is 10 to 20 rpm.

[0053] According to the present invention, preferably, the enhanced spraying time is 10 to 30 minutes.

[0054] According to the present invention, preferably, the drying temperature is 100-120°C and the time is 2-10 hours.

[0055] According to the present invention, preferably, the calcination temperature is 400-600°C and the time is 2-10 hours.

[0056] In this invention, the rotating packing 107 can be a stainless steel wire mesh packing or a stainless steel cylindrical packing.

[0057] According to the present invention, the preparation of the above-mentioned catalyst is carried out in a rotation-enhanced impregnation apparatus, which includes: a rotation-enhanced packed bed 103, a liquid storage tank 104, a liquid pump 105, a first motor 101, and a second motor 102.

[0058] The rotating reinforced packing bed 103 has a cylindrical structure and a liquid distributor 106 is provided in the center. The lower end is provided with an impregnation liquid outlet 111, which is used to discharge the impregnation liquid that has not been impregnated and return it to the storage tank 104.

[0059] A rotating packing 107 and a carrier ring 108 are sequentially arranged on the outside of the liquid distributor 106, and the carrier ring 108 is filled with carrier particles 109.

[0060] The liquid distributor 106, the rotating packing 107, and the carrier ring 108 are all cylindrical structures;

[0061] The first motor 101 is used to drive the carrier ring 108 to rotate and control the speed, and the second motor 102 is used to drive the rotating packing 107 to rotate and control the speed.

[0062] One end of the liquid distributor 106 is closed, and the other end is provided with an impregnation liquid inlet 110. Multiple spray holes are evenly distributed on the cylinder wall to spray the impregnation liquid into the inner side of the rotating packing 107.

[0063] The inlet of the liquid pump 105 is connected to the liquid storage tank 104, and the outlet is connected to the impregnation liquid inlet 110, which is used to pump the impregnation liquid in the liquid storage tank 104 into the liquid distributor 106.

[0064] In this invention, under the action of high-speed centrifugal force, the impregnation liquid is sheared into tiny liquid micro-elements by the rotating packing 107 and comes into contact with the carrier particles 109 in the carrier ring 108 at an extremely high tangential initial velocity; the carrier ring 108 rotates at a low speed to ensure that the carrier particles 109 are in full contact with the impregnation liquid micro-elements; the impregnated liquid is returned to the storage tank 104 for liquid circulation.

[0065] According to the present invention, preferably, the temperature for hydrogen reduction is 400-500°C and the reduction time is 2-8 hours.

[0066] According to the present invention, a method for treating carbon oxide impurities in hydrogen for fuel cells with a reducing catalyst may be as follows: contacting the catalyst with hydrogen for fuel cells, for example, loading the catalyst into a fixed-bed reactor, and then passing the hydrogen for fuel cells through the fixed-bed reactor.

[0067] According to the present invention, preferably, the temperature for hydrogen purification is 100–200°C, and the pressure for hydrogen purification is 0.1–10 MPa.

[0068] According to the present invention, preferably, the space velocity of hydrogen used in the hydrogen-purified fuel cell is less than 5000 h⁻¹. -1 .

[0069] According to the present invention, preferably, the concentration of carbon oxides in the hydrogen used in the hydrogen-purified fuel cell is less than 50 ppm.

[0070] In this invention, the method for purifying hydrogen for fuel cells is carried out in a fixed-bed reactor. Before the catalyst reacts with hydrogen containing carbon oxides, hydrogen is first introduced to reduce part of the nickel oxide in the methanation catalyst to active nickel. Then, hydrogen-rich gas containing trace amounts of carbon oxides is contacted with the catalyst to remove the carbon oxides.

[0071] The present invention will be described in more detail below through embodiments.

[0072] The testing instruments and conditions used in this embodiment are as follows:

[0073] The specific surface area (BET) and pore volume parameters were both measured by the (N2) adsorption-desorption method.

[0074] The nickel component dispersion and average nickel particle size were determined by hydrogen chemisorption.

[0075] The raw materials used in the examples are from the following sources:

[0076] The molded alumina carrier was produced by Beijing Research Institute of Chemical Industry;

[0077] All other reagents used were commercially available and of analytical grade.

[0078] The rotation-enhanced impregnation apparatus used in catalyst preparation, such as Figure 1 As shown, the device includes: a rotary reinforced packing bed 103, a liquid storage tank 104, a liquid pump 105, a first motor 101, and a second motor 102;

[0079] The rotating reinforced packing bed 103 has a cylindrical structure and a liquid distributor 106 is provided in the center. The lower end is provided with an impregnation liquid outlet 111, which is used to discharge the impregnation liquid that has not been impregnated and return it to the storage tank 104.

[0080] A rotating packing 107 and a carrier ring 108 are sequentially arranged on the outside of the liquid distributor 106, and the carrier ring 108 is filled with carrier particles 109.

[0081] The liquid distributor 106, the rotating packing 107, and the carrier ring 108 are all cylindrical structures;

[0082] The first motor 101 is used to drive the carrier ring 108 to rotate and control the speed, and the second motor 102 is used to drive the rotating packing 107 to rotate and control the speed.

[0083] One end of the liquid distributor 106 is closed, and the other end is provided with an impregnation liquid inlet 110. Multiple spray holes are evenly distributed on the cylinder wall to spray the impregnation liquid into the inner side of the rotating packing 107.

[0084] The inlet of the liquid pump 105 is connected to the liquid storage tank 104, and the outlet is connected to the impregnation liquid inlet 110, which is used to pump the impregnation liquid in the liquid storage tank 104 into the liquid distributor 106.

[0085] Preparation Example 1

[0086] Adopting such Figure 1 The catalyst preparation apparatus shown in the diagram uses 50g of molded alumina support (produced by Beijing Research Institute of Chemical Industry, with a BET specific surface area of ​​143m²). 2 / g, pore volume is 0.74m 3 The catalyst precursor (containing 15 wt% nickel and 0.5 wt% magnesium) was loaded into a wire mesh carrier ring. An impregnation solution containing nickel nitrate and magnesium nitrate (containing 15 wt% nickel and 0.5 wt% magnesium) was placed in a storage tank 104. The rotating reinforced packed bed 103 was started, with the rotating packing 107 rotating at 2000 rpm and the wire mesh carrier ring rotating at 10 rpm. The impregnation solution was pumped into a liquid distributor 106 via a liquid pump 105. After 30 minutes of reinforced impregnation, the catalyst precursor was removed and then dried at 120°C for 4 hours and calcined at 600°C for 6 hours. The obtained catalyst was subjected to the above steps twice more, finally yielding a catalyst with a nickel content of 39% and a magnesium content of 0.40%, denoted as A1.

[0087] Preparation Example 2

[0088] Adopting such Figure 1The catalyst preparation apparatus shown in the diagram uses 50g of molded alumina support (produced by Beijing Research Institute of Chemical Industry, with a BET specific surface area of ​​143m²). 2 / g, pore volume is 0.74m 3 The catalyst precursor (containing 15 wt% nickel and 0.5 wt% calcium) was loaded into a wire mesh carrier ring. An impregnation solution containing nickel nitrate and calcium nitrate (containing 15 wt% nickel and 0.5 wt% calcium) was placed in a storage tank 104. The rotating reinforced packed bed 103 was started, with the rotating packing 107 rotating at 2000 rpm and the wire mesh carrier ring rotating at 10 rpm. The impregnation solution was pumped into a liquid distributor 106 via a liquid pump 105. After 30 minutes of reinforced impregnation, the catalyst precursor was removed and then dried at 120°C for 4 hours and calcined at 600°C for 6 hours. The obtained catalyst was subjected to the above steps twice more, finally yielding a catalyst with a nickel content of 39% and a calcium content of 0.37%, denoted as A2.

[0089] Preparation Example 3

[0090] Adopting such Figure 1 The catalyst preparation apparatus shown in the diagram uses 50g of molded alumina support (produced by Beijing Research Institute of Chemical Industry, with a BET specific surface area of ​​143m²). 2 / g, pore volume is 0.74m 3 The catalyst precursor (containing 15 wt% nickel and 0.5 wt% lanthanum) was loaded into a wire mesh carrier ring. An impregnation solution containing nickel nitrate and lanthanum nitrate (containing 15 wt% nickel and 0.5 wt% lanthanum) was placed in a storage tank 104. The rotating reinforced packed bed 103 was started, with the rotating packing 107 rotating at 2000 rpm and the wire mesh carrier ring rotating at 10 rpm. The impregnation solution was pumped into a liquid distributor 106 via a liquid pump 105. After 30 minutes of reinforced impregnation, the catalyst precursor was removed and then dried at 120°C for 4 hours and calcined at 600°C for 6 hours. The obtained catalyst was subjected to the above steps twice more, finally yielding a catalyst with a nickel content of 39% and a lanthanum content of 1.14%, denoted as A3.

[0091] Preparation Example 4

[0092] Adopting such Figure 1 The catalyst preparation apparatus shown in the diagram uses 50g of molded alumina support (produced by Beijing Research Institute of Chemical Industry, with a BET specific surface area of ​​143m²). 2 / g, pore volume is 0.74m 3The catalyst precursor (containing 15 wt% nickel and 0.5 wt% cerium) was loaded into a wire mesh carrier ring. An impregnation solution containing nickel nitrate and cerium nitrate (containing 15 wt% nickel and 0.5 wt% cerium) was placed in a storage tank 104. The rotating reinforced packed bed 103 was started, with the rotating packing 107 rotating at 2000 rpm and the wire mesh carrier ring rotating at 10 rpm. The impregnation solution was pumped into a liquid distributor 106 via a liquid pump 105. After 30 minutes of reinforced impregnation, the catalyst precursor was removed and then dried at 120°C for 4 hours and calcined at 600°C for 6 hours. The obtained catalyst was subjected to the above steps twice more, finally yielding a catalyst with a nickel content of 39% and a cerium content of 1.15%, denoted as A4.

[0093] Preparation Example 5

[0094] Adopting such Figure 1 The catalyst preparation apparatus shown in the diagram uses 50g of molded alumina support (produced by Beijing Research Institute of Chemical Industry, with a BET specific surface area of ​​193m²). 2 / g, pore volume is 0.94m 3 The catalyst precursor (containing 15 wt% nickel and 0.5 wt% lanthanum) was loaded into a wire mesh carrier ring. An impregnation solution containing nickel nitrate and lanthanum nitrate (containing 15 wt% nickel and 0.5 wt% lanthanum) was placed in a storage tank 104. The rotating reinforced packed bed 103 was started, with the rotating packing 107 rotating at 2000 rpm and the wire mesh carrier ring rotating at 10 rpm. The impregnation solution was pumped into a liquid distributor 106 via a liquid pump 105. After 30 minutes of reinforced impregnation, the catalyst precursor was removed. It was then dried at 120℃ for 4 hours and calcined at 600℃ for 6 hours. The above steps were repeated twice to obtain a catalyst with a nickel content of 40% and a lanthanum content of 1.14%, denoted as A5.

[0095] Preparation Example 6

[0096] Adopting such Figure 1 The catalyst preparation apparatus shown in the diagram uses 50g of molded alumina support (produced by Beijing Research Institute of Chemical Industry, with a BET specific surface area of ​​231m²). 2 / g, pore volume 1.20m 3 The catalyst precursor (containing 15 wt% nickel and 0.5 wt% lanthanum) was loaded into a wire mesh carrier ring. An impregnation solution containing nickel nitrate and lanthanum nitrate (containing 15 wt% nickel and 0.5 wt% lanthanum) was placed in a storage tank 104. The rotating reinforced packed bed 103 was started, with the rotating packing 107 rotating at 2000 rpm and the wire mesh carrier ring rotating at 10 rpm. The impregnation solution was pumped into a liquid distributor 106 via a liquid pump 105. After 30 minutes of reinforced impregnation, the catalyst precursor was removed and then dried at 120°C for 4 hours and calcined at 600°C for 6 hours. The obtained catalyst was subjected to the above steps twice more, finally yielding a catalyst with a nickel content of 41% and a lanthanum content of 1.15%, denoted as A6.

[0097] Comparative Example 1

[0098] Using the traditional equal-volume impregnation method, 50g of molded alumina carrier (produced by Beijing Chemical Research Institute, with a BET specific surface area of ​​143m²) was impregnated. 2 / g, pore volume is 0.74m 3 The catalyst was impregnated with a nickel nitrate / magnesium nitrate impregnation solution containing 15wt% nickel and 0.5wt% magnesium, and then dried at 100℃ for 10h and calcined at 400℃ for 10h. After repeating the impregnation, drying and calcination steps twice, a catalyst with a nickel content of 39% and a magnesium content of 0.40% was finally obtained, denoted as D1.

[0099] Test Example 1

[0100] The catalyst samples A1-6 and D1 were characterized by chemical pulse adsorption of hydrogen. The specific method was as follows: the samples were reduced in a hydrogen atmosphere at 450℃ for 4 hours, purged with argon at 450℃ for 2 hours, and then cooled to 45℃. At this temperature, pulse adsorption was performed with a 10% hydrogen-argon mixture. Finally, the nickel dispersion and nickel particle size of the reduced catalyst were obtained. The results are shown in Table 1.

[0101] Table 1

[0102]

[0103]

[0104] Example 1

[0105] Take 10 ml of catalyst samples from both A1-6 and D1, and load them into stainless steel fixed-bed reactors. Purge with high-purity hydrogen at a flow rate of 300 ml / min, and heat to 450 °C to reduce the catalyst samples for 4 hours. Switch to high-purity nitrogen at a flow rate of 300 ml / min. Once the temperature drops to the set value, introduce feed gas. The feed gas contains 50 ppm of CO + CO2. Other conditions are listed in Table 2. The composition of the gas after the reaction was analyzed by gas chromatography using an FID detector.

[0106] Table 2

[0107]

[0108] Compared to the commonly used PSA method for removing carbon oxides from hydrogen used in fuel cells, the catalytic method of this invention has a higher hydrogen yield; and the operation process is simple, requiring only one reaction step to reduce the concentration of carbon oxides to below 0.2 ppm, without the need for repeated desorption and regeneration operations.

[0109] Furthermore, compared to the catalyst prepared by the conventional equal-volume impregnation method in Comparative Example 1, the catalysts prepared in Examples 1-6 of this invention employ the following methods: Figure 1The catalysts A1-6 prepared by the catalyst preparation apparatus shown have high nickel dispersion and small nickel particle size. This is because the alumina support is loosely packed in the wire mesh support ring, and the rotation of the wire mesh support ring can drive the slow displacement of the support, so that the impregnation liquid formed by centrifugal force into liquid mist and droplets can be uniformly sprayed onto the surface of the support at extremely high speed.

[0110] Furthermore, Table 2 shows that at reaction temperatures of 120 and 150°C, the concentration of carbon oxides after the A1 catalytic reaction was still below 0.2 ppm, while the catalytic activity of D1 decreased with decreasing reaction temperature. This indicates that although the catalysts prepared by conventional impregnation and the impregnation method of the present invention can completely remove carbon oxides from hydrogen for fuel cells under high temperature conditions, the catalyst prepared by the impregnation method of the present invention has better activity under low temperature conditions. This is because the catalyst of the present invention has smaller nickel particle size and nickel dispersion, and can exhibit better low-temperature catalytic activity in the purification of carbon oxides in hydrogen for fuel cells.

[0111] The embodiments of the present invention have been described above. These descriptions are exemplary and not exhaustive, nor are they 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.

Claims

1. A method for purifying hydrogen for fuel cells, characterized in that, The method includes the following steps: (1) Hydrogen reduction: The catalyst is reduced in a hydrogen atmosphere to obtain a reduced catalyst; (2) Hydrogen purification: treating carbon oxide impurities in hydrogen for fuel cells with the reduction catalyst described above; The catalyst comprises an alumina support and a nickel compound and an auxiliary metal compound supported thereon, wherein, based on the weight of the catalyst, the nickel content is 5-50 wt% and the auxiliary metal content is 0.01-10 wt%. In the reduction catalyst, the nickel dispersion is 1.0~2.5%; the nickel particle size is 10~100nm; The nickel compound is nickel oxide; The compound of the auxiliary metal is at least one of the oxides of magnesium, calcium, lanthanum, barium, and cerium; The catalyst is prepared by a method comprising the following steps: Step 1: Use a mixed salt solution containing metallic nickel salt and auxiliary metallic salt as the impregnation solution; Step 2: Load the alumina carrier into the carrier ring, pump the impregnation solution into the liquid distributor in the center of the rotating packing, and spray it evenly into the inner side of the rotating packing through the liquid distributor. Step 3: The impregnation liquid inside the rotating packing is centrifugally sprayed onto the alumina carrier in the outer rotating carrier ring by the rotation of the rotating packing. Then the impregnated alumina carrier is dried and calcined. Step 4: Optionally repeat the operations of Steps 2 and 3 at least once to obtain the catalyst; The carrier ring is a wire mesh carrier ring; The rotational speed of the rotating packing is 1000~2000 rpm; The rotational speed of the carrier ring is 10~20 rpm.

2. The purification method according to claim 1, characterized in that, The nickel content is 10-45 wt% (elemental basis), and the auxiliary metal content is 0.1-1.5 wt% (elemental basis). In the reduction catalyst, the nickel particle size is 20~65nm.

3. The purification method according to claim 1, characterized in that, The nickel salt is selected from at least one of nickel nitrate, nickel sulfate, and basic nickel carbonate; The auxiliary metal salt is selected from at least one of the metal salts of magnesium, calcium, lanthanum, barium, and cerium.

4. The purification method according to claim 1, characterized in that, The auxiliary metal salt is selected from at least one of the nitrates, sulfates or carbonates of magnesium, calcium, lanthanum, barium or cerium.

5. The purification method according to claim 1, characterized in that, In the mixed salt solution, the mass percentage concentration of metallic nickel is 1-15%; the mass percentage concentration of the additive metal is 0.01-5%.

6. The purification method according to claim 1, characterized in that, In the mixed salt solution, the mass percentage concentration of metallic nickel is 5-15%; the mass percentage concentration of the additive metal is 0.1-1%.

7. The purification method according to claim 1, characterized in that, The rotating packing material is a wire mesh or a cylindrical packing material; The spraying time is 10-30 minutes; The drying temperature is 100~120℃, and the time is 2~10h; The roasting temperature is 400~600℃ and the time is 2~10h.

8. The purification method according to any one of claims 1-7, characterized in that, The catalyst is prepared in a rotary impregnation apparatus, which includes a rotary-strengthened packed bed, a liquid storage tank, a liquid pump, a first motor, and a second motor. The rotating reinforced packing bed has a cylindrical structure with a liquid distributor in the center and an impregnation liquid outlet at the bottom to discharge the unimpregnated impregnation liquid and return it to the storage tank. A rotating packing and a carrier ring are arranged sequentially on the outside of the liquid distributor, and the carrier ring is filled with carrier particles. The liquid distributor, rotating packing, and carrier ring are all cylindrical structures. The first motor is used to drive the carrier ring to rotate and control the speed, and the second motor is used to drive the rotating packing to rotate and control the speed. One end of the liquid distributor is closed, and the other end is provided with an impregnation liquid inlet. Multiple spray holes are evenly distributed on the cylinder wall to spray the impregnation liquid into the inside of the rotating packing. The inlet of the liquid pump is connected to the storage tank, and the outlet is connected to the impregnation liquid inlet, which is used to pump the impregnation liquid in the storage tank into the liquid distributor.

9. The purification method according to claim 1, characterized in that, The hydrogen reduction temperature is 400~500℃, and the reduction time is 2~8h; The temperature for hydrogen purification is 100~200℃; The pressure for hydrogen purification is 0.1~10 MPa; The hydrogen space velocity for the fuel cell purified by the hydrogen is less than 5000 h⁻¹. -1 ; The hydrogen used in the fuel cell, after hydrogen purification, has a carbon oxide concentration of less than 50 ppm.

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