Water gas shift catalyst, method for preparing and using the same, and method for water gas shift reaction

Abstract

The application relates to the technical field of water vapor shift, and discloses a water vapor shift catalyst, a preparation method and application thereof, and a water vapor shift reaction method, wherein the catalyst comprises aluminum oxide, active elements and auxiliary elements; the auxiliary elements are selected from at least one of Co, Ni, Cr, Cu and Ce; the active elements comprise divalent iron and trivalent iron, and the atomic ratio of the divalent iron and the trivalent iron on the surface of the catalyst is not less than 0.3 measured by XPS. The catalyst is applied to a water vapor shift reaction, can be suitable for a low water-gas ratio condition, has a high CO conversion rate and a high hydrogen production rate under a high air speed condition, has good heat-resistant activity, and has a high activity retention rate after high-temperature treatment.

Description

Technical Field

[0001] This invention relates to the field of water vapor shift technology, specifically to a water vapor shift catalyst, its preparation method and application, and a method for water vapor shift reaction. Background Technology

[0002] Currently, steam reforming (SRM) of methane is a mature industrial hydrogen production technology. To improve hydrogen yield, a water-gas shift reaction (WGS) is required after the reforming process to react excess CO and further increase the H2 content in the atmosphere, thereby increasing hydrogen yield. In addition, the WGS has also seen important applications in the field of new energy vehicles in recent years. The electrode materials of fuel cells are mainly composed of Pt, which is easily deactivated in the presence of carbon monoxide. Therefore, placing the WGS reactor before the fuel cell converts carbon monoxide into hydrogen and CO2. Thus, the water-gas shift reaction (WGS) plays a crucial industrial role in regulating and increasing H2 concentration.

[0003] Commercial iron oxide catalysts using chromium oxide as a structural aid have been used for over 60 years. Besides preventing the sintering of iron oxide crystals, Cr₂O₃ / CrO₃ can also enhance the inherent catalytic activity of Fe₂O₃. Although chromium oxides have proven to be excellent aids, hexavalent chromium is a heavy metal toxic to humans, organisms, and cells, and a serious environmental pollutant. Its water solubility allows it to leach from catalysts via condensed steam or cold water. Both fresh and spent commercial high-temperature conversion Fe-Cr catalysts contain hexavalent chromium (Cr₂O₃). 6+ The processing cost is very high.

[0004] CN107649142A discloses the use of Mn, Mg, and Cr as promoters to improve the high-temperature stability of Fe-based catalysts, but it still contains a low Cr content; CN103272600A discloses a hydrothermal synthesis of a supported copper-iron catalyst, but its hydrothermal reaction time is long and the process is cumbersome; CN104014345A discloses the synthesis of Cu / CeO2 catalysts by deposition precipitation method, but the deposition consumes a lot of heat and the catalyst preparation cost is high.

[0005] The main problems faced by existing water-gas shift reaction surfaces include severe methanation side reactions, low space-time yield, high catalyst cost, and serious chromium contamination. Therefore, developing chromium-free, highly selective catalysts with simple preparation processes while ensuring hydrothermal stability is both a challenge and a direction for realizing the industrial application of green shift catalysts. Summary of the Invention

[0006] The purpose of this invention is to overcome the problems of poor heat resistance and low hydrogen production rate of existing water-gas shift catalysts, and to provide a water-gas shift catalyst, its preparation method and application, and a method for water-gas shift reaction. This catalyst has high thermal stability and resistance to hydrothermal sintering.

[0007] To achieve the above objectives, the present invention provides a water-gas shift catalyst, wherein the catalyst comprises alumina, an active element, and an auxiliary element; the auxiliary element is selected from at least one of Co, Ni, Cr, Cu, and Ce; the active element comprises ferrous iron and ferric iron, and the atomic ratio of ferrous iron to ferric iron on the catalyst surface is not less than 0.3 as determined by XPS.

[0008] Preferably, the total pore volume of the catalyst is 0.01-0.6 mL / g, more preferably 0.3-0.5 mL / g;

[0009] Preferably, the catalyst has an average pore size of 5-15 nm, more preferably 8-12 nm.

[0010] A second aspect of this invention provides a method for preparing a water-vapor shift catalyst, comprising the following steps:

[0011] (1) In the presence of a first dispersant, aluminum isopropoxide, a first template agent and an acid are mixed to obtain a first solution;

[0012] (2) In the presence of a second dispersant, a ferrous iron source, a ferric iron source, a soluble compound containing an auxiliary element, and a second template agent are mixed to obtain a second solution; wherein, based on the element of iron, the molar ratio of the ferrous iron source to the ferric iron source is 1-3:1; the auxiliary element is selected from at least one of Co, Ni, Cr, Cu, and Ce;

[0013] (3) Under stirring conditions, the first solution and the second solution are mixed to obtain a gel;

[0014] (4) The gel is dried, washed and calcined.

[0015] Preferably, the drying temperature in step (4) is not lower than 90°C, preferably 100-150°C, and more preferably 110-130°C; the drying time is 12-84h, preferably 24-48h.

[0016] The third aspect of the present invention provides the application of the above-described water-vapor shift catalyst or the water-vapor shift catalyst prepared by the above-described preparation method in water-vapor shift reactions.

[0017] The fourth aspect of the present invention provides a method for a water-vapor shift reaction, comprising: contacting a CO-containing feed gas and water vapor with a catalyst to perform water-vapor shift reaction under water-vapor shift reaction conditions;

[0018] The catalyst is either the water-vapor shift catalyst of the first aspect or the water-vapor shift catalyst prepared by the preparation method provided in the second aspect.

[0019] The water-gas shift catalyst provided by this invention comprises alumina, active elements, and auxiliary elements, and the atomic ratio of divalent iron to trivalent iron on the catalyst surface is not less than 0.3. The inventors of this invention discovered in their research that the Fe on the catalyst surface... 2+ / Fe 3+ The composition ratio is crucial for catalyst activity and stability. Catalysts with the above-mentioned composition are suitable for low water-to-gas ratio conditions in water-gas change reactions, exhibiting high CO conversion and hydrogen production rates under high space velocities, good heat resistance, and high activity retention after high-temperature treatment. Preferably, the catalyst possesses a large number of uniform mesoporous structures with a large total pore volume and small average pore size. This not only helps stabilize the catalyst structure and improve its thermal stability but also enhances its catalytic activity and increases the hydrogen production rate.

[0020] The method for preparing the water-gas shift catalyst provided by this invention employs a one-step self-assembly method to synthesize the catalyst, generating almost no wastewater during the preparation process and simplifying the production flow. By introducing auxiliary agents and synergistically interacting with both ferrous and ferric iron sources, the resulting catalyst surface possesses suitable Fe content. 2+ / Fe 3+ Proportion. In preferred cases, by introducing aluminum isopropoxide and simultaneously controlling the rapid drying of the gel to shorten the growth time, a uniform mesoporous structure can be formed with a large total pore volume and a small average pore size. The resulting catalyst exhibits good heat resistance and high activity retention after high-temperature treatment. Attached Figure Description

[0021] Figure 1 This is a TEM image of catalyst A1 prepared in Example 1 of the present invention;

[0022] Figure 2 These are the XPS curves and Fe 2p peak fractionation results of catalyst A1 prepared in Example 1 of this invention. Detailed Implementation

[0023] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0024] The first aspect of the present invention provides a water-gas shift catalyst, the catalyst comprising alumina, an active element, and an auxiliary element; the auxiliary element is selected from at least one of Co, Ni, Cr, Cu, and Ce; the active element comprises ferrous iron and ferric iron, and the atomic ratio of ferrous iron to ferric iron on the catalyst surface is not less than 0.3 as determined by XPS.

[0025] The inventors of this invention discovered in their research that Fe on the catalyst surface 2+ / Fe 3+ The composition of the catalyst is crucial to its activity and stability. Catalysts with the above-mentioned composition are suitable for low water-to-gas ratio conditions in water-gas change reactions, exhibiting high CO conversion and hydrogen production rates under high space velocities, good heat resistance, and high activity retention after high-temperature treatment. However, the iron element in existing iron-based catalysts is almost entirely Fe. 3+ .

[0026] According to some preferred embodiments of the present invention, the atomic ratio of ferrous iron (Fe2+) to ferric iron (Fe3+) on the catalyst surface, as measured by XPS, is 0.4-1. For example, the atomic ratio of ferrous iron to Fe3+ on the catalyst surface measured by XPS can be a specific value such as 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, or 1, or any range between the two. Preferably, the atomic ratio of ferrous iron to Fe3+ on the catalyst surface, as measured by XPS, is 0.5-0.8. An atomic ratio of ferrous iron to Fe3+ on the catalyst surface within the above-mentioned preferred range is beneficial for further improving reaction activity and stability, and exhibiting good heat resistance.

[0027] In this invention, in-situ XPS characterization was performed on a Thermo Fisher-VG ESCALAB 250 X-ray photoelectron spectrometer, using AlKα X-rays with a monochromatic power of 150 W as the excitation source. The charging effect was corrected for by the Al 2p peak (74.7 eV) of the support Al2O3 or the Si 2p peak (103.6 eV) of SiO2. The reduction conditions were: heating rate of 5 °C / min, pure H2 gas, reaction pressure of 0.12 MPa, and reduction for 3 h after heating to the target temperature.

[0028] In some preferred embodiments of the present invention, the molar ratio of the active element to the auxiliary element is 1-50:1, preferably 5-20:1. In the present invention, the auxiliary element in the catalyst helps to stabilize the ferrous iron on the catalyst surface, and the synergistic effect of the auxiliary element with ferrous and ferric iron is beneficial to providing higher activity in the water-gas shift reaction.

[0029] According to some preferred embodiments of the present invention, the promoter element is selected from at least two of Co, Ni, Cr, Cu, and Ce. In the above-mentioned preferred embodiments, this is beneficial to improving the water-gas shift catalytic activity of the catalyst. To further improve the catalyst activity at low temperatures, the promoter element preferably includes Cu, and optionally Ni and / or Cr. Using the above-mentioned preferred composition facilitates the water-gas shift reaction to proceed under relatively mild reaction conditions and exhibits high activity.

[0030] In a further preferred embodiment, the ratio of the molar amount of Cu to the total molar amount of Ni and / or Cr in the auxiliary elements is 0.05-1:1, preferably 0.1-0.3:1.

[0031] In this invention, the active element and the auxiliary element exist in the form of oxides.

[0032] According to some preferred embodiments of the present invention, based on the mass of the catalyst, the alumina content is 20-80 wt%, preferably 40-70 wt%; the active element content, calculated as oxide, is 20-80 wt%, preferably 30-60 wt%; and the auxiliary element content, calculated as oxide, is 0.1-10 wt%, preferably 1-8 wt%. In the present invention, the iron content is calculated as ferric oxide.

[0033] In this invention, the composition of the catalyst was determined by X-ray fluorescence spectroscopy (XRF).

[0034] According to some preferred embodiments of the present invention, the total pore volume of the catalyst is 0.01-0.6 mL / g, preferably 0.2-0.5 mL / g.

[0035] In a preferred embodiment, the catalyst provided by the present invention has a small average pore size, with mesoporous structure as the main pore distribution. This is beneficial for stabilizing the catalyst structure, improving the thermal stability of the catalyst, and also for improving the catalytic activity of the catalyst and increasing the hydrogen production rate.

[0036] Preferably, the average pore size of the catalyst is 5-15 nm, more preferably 8-12 nm, and can be typical but not limiting values ​​such as 8 nm, 8.5 nm, 9 nm, 9.5 nm, 10 nm, 10.5 nm, 11 nm, 11.5 nm, 12 nm, or a range between the two.

[0037] The average pore size of the catalyst was analyzed using low-temperature N2 isothermal adsorption-desorption and conventional BET calculations. Before analysis, the sample was dried at 120℃ for 2 h, followed by vacuum treatment at 300℃. High-purity nitrogen was used as the adsorption medium. Adsorption / desorption experiments were conducted under liquid nitrogen cooling conditions (-196℃).

[0038] A second aspect of this invention provides a method for preparing a water-vapor shift catalyst, comprising the following steps:

[0039] (1) In the presence of a first dispersant, aluminum isopropoxide, a first template agent and an acid are mixed to obtain a first solution;

[0040] (2) In the presence of a second dispersant, a ferrous iron source, a ferric iron source, a soluble compound containing an auxiliary element, and a second template agent are mixed to obtain a second solution; wherein, based on the element of iron, the molar ratio of the ferrous iron source to the ferric iron source is 1-3:1; the auxiliary element is selected from at least one of Co, Ni, Cr, Cu, and Ce;

[0041] (3) Under stirring conditions, the first solution and the second solution are mixed to obtain a gel;

[0042] (4) The gel is dried, washed and calcined.

[0043] According to the present invention, a catalyst is synthesized using a one-step self-assembly method. By introducing ferrous and ferric sources, appropriate amounts of ferrous and ferric iron are introduced into the catalyst. With the synergistic effect of the promoters, the surface of the obtained catalyst has a suitable Fe content. 2+ / Fe 3+ Ratio. Preferably, the molar ratio of divalent iron source to trivalent iron source is 1.5-2.5:1, based on iron element content.

[0044] According to some preferred embodiments of the present invention, the first template agent and the second template agent are each independently selected from at least one of cetyltrimethylammonium bromide (CTAB), polyoxyethylene / polyoxypropylene / polyoxyethylene amphiphilic block copolymer (F127), polyethylene oxide-polyoxypropylene-polyoxyethylene triblock copolymer (P123), polyoxyethylene-polyoxypropylene block polyether (F108), polyethylene glycol (PEG), and polyoxyethylene ether. The first template agent and the second template agent may be the same or different; preferably, the first template agent and the second template agent are the same.

[0045] According to some preferred embodiments of the present invention, in step (1), the mass ratio of the first template agent to aluminum isopropoxide is 0.1-1:1, preferably 0.2-0.8:1.

[0046] According to some preferred embodiments of the present invention, the mass ratio of aluminum isopropoxide to acid is 0.1-10:1, preferably 1-5:1. In the above preferred cases, this is beneficial for the formation of mesoporous alumina.

[0047] Preferably, the acid is citric acid and / or nitric acid.

[0048] According to some preferred embodiments of the present invention, the amount of the first dispersant is such that the concentration of aluminum isopropoxide in the first solution is 0.05-1 g / mL, preferably 0.1-0.5 g / mL.

[0049] According to some preferred embodiments of the present invention, the mass ratio of the second template agent to the mass of the first template agent is 0.1-1:1.

[0050] According to some preferred embodiments of the present invention, the promoter element is selected from at least two of Co, Ni, Cr, Cu, and Ce. In the above-mentioned preferred embodiments, this is beneficial to improving the water-gas shift catalytic activity of the catalyst. To further improve the catalyst activity at low temperatures, the promoter element preferably includes Cu, and optionally Ni and / or Cr. By adopting the above-mentioned preferred composition, the water-gas shift reaction is facilitated to proceed under relatively mild reaction conditions and exhibits high activity.

[0051] According to some preferred embodiments of the present invention, the molar ratio of Cu to the total molar ratio of Ni and / or Cr in the auxiliary elements is 0.05-1:1, preferably 0.1-0.3:1.

[0052] According to some preferred embodiments of the present invention, the ratio of the total molar amount of the divalent iron source and the trivalent iron source to the molar amount of the soluble compound containing the auxiliary element, based on metal elements, is 1-50:1, preferably 5-20:1. In the above preferred cases, it is beneficial to form a suitable ratio of divalent and trivalent iron on the catalyst surface, and the synergistic effect of the auxiliary element with divalent and trivalent iron is beneficial to the activity and stability in the water-gas shift reaction.

[0053] The present invention has a wide range of choices for the specific types of divalent iron sources, trivalent iron sources, and soluble compounds containing auxiliary elements, as long as the corresponding metal source can be provided. Those skilled in the art can make the selection according to the actual situation.

[0054] According to some preferred embodiments of the present invention, the ferrous iron source, the ferric iron source, and the soluble compound containing the auxiliary element are each independently selected from inorganic and / or organic salts of metals, preferably at least one of nitrates, sulfates, halides, acetates, and formates. For example, the ferrous iron source can be ferrous chloride, and the ferric iron source can be ferric nitrate.

[0055] According to some preferred embodiments of the present invention, the stirring time in step (3) is 1-10 hours, preferably 3-6 hours.

[0056] According to some preferred embodiments of the present invention, the amounts of the first solution and the second solution are such that, based on the total amount of the catalyst obtained, the alumina content is 20-80 wt%, preferably 40-70 wt%; the active element content, calculated as oxide, is 20-80 wt%, preferably 30-60 wt%; and the auxiliary element content, calculated as oxide, is 0.1-10 wt%, preferably 1-8 wt%.

[0057] According to some preferred embodiments of the present invention, the drying temperature in step (4) is not lower than 90°C, preferably 100-150°C, and more preferably 110-130°C; the drying time is 12-84 h, preferably 24-72 h. Using the above-mentioned preferred drying conditions is beneficial to further improve the heat resistance activity of the catalyst. The reason for this may be that under the above conditions, the gel dries rapidly, the growth rate is fast, and the time is short, thereby forming a uniform mesoporous structure in the catalyst.

[0058] According to some preferred embodiments of the present invention, the calcination conditions include: a calcination temperature of 300-500℃, preferably 350-450℃; and a calcination time of 2-8h, preferably 4-6h.

[0059] Preferably, the preparation method further includes: shaping and sieving the product obtained by calcination; the shaping method can be selected according to actual application needs and is well known to those skilled in the art, for example, it can be tableting.

[0060] The third aspect of the present invention provides the application of the above-described water-vapor shift catalyst or the water-vapor shift catalyst prepared by the above-described preparation method in water-vapor shift reactions.

[0061] The fourth aspect of the present invention provides a method for a water-vapor shift reaction, comprising: contacting a CO-containing feed gas and water vapor with a catalyst to perform water-vapor shift reaction under water-vapor shift reaction conditions;

[0062] The catalyst is either the water-vapor shift catalyst described above or the water-vapor shift catalyst prepared by the above method.

[0063] In this invention, the water-gas shift reaction can achieve a high CO conversion rate and a high hydrogen production rate under high space velocity conditions.

[0064] According to some preferred embodiments of the present invention, the water-gas shift reaction conditions include: a reaction temperature of 300-500℃, preferably 350-450℃; a reaction pressure of 0.1-5MPa, preferably 1-2MPa; and a mass hourly space velocity (MSV) of the feed gas of 5000-20000 h⁻¹. -1 Preferably 10000-18000h -1The water-to-carbon ratio is 2.4-4, preferably 2.8-3.5.

[0065] Preferably, the water-vapor shift reaction is carried out in a fixed-bed reactor.

[0066] According to some preferred embodiments of the present invention, the method further includes: pre-treating the catalyst by reduction in a reducing atmosphere containing H2 and / or CO before the contact.

[0067] Preferably, the conditions for the reduction pretreatment include: a temperature of 200-600℃; a time of 1-12 h; a pressure of 0.1-1 MPa; and a space velocity of 500-20000 h⁻¹. -1 More preferably, the temperature is 300-400℃; the time is 2-6 hours; the pressure is 0.1-1 MPa; and the space velocity is 5000-20000. -1 .

[0068] Preferably, the reducing atmosphere may further contain water vapor and / or carbon dioxide. Preferably, the total volume content of H2 and / or CO in the reducing atmosphere is not less than 30%, and more preferably 35-65%.

[0069] The present invention will be described in detail below through embodiments.

[0070] Unless otherwise specified, all raw materials used in the following examples and comparative examples are commercially available.

[0071] Pore ​​volume and average pore size of the catalyst were measured using low-temperature N2 isothermal adsorption-desorption and conventional BET calculations. Before analysis, the sample was dried at 120℃ for 2 hours, followed by vacuum treatment at 300℃. High-purity nitrogen was used as the adsorption medium. Adsorption / desorption experiments were conducted under liquid nitrogen cooling conditions (-196℃).

[0072] The composition of the catalyst was determined by XRF method.

[0073] The valence state of iron on the catalyst surface and the contents of ferrous and ferric iron were determined by X-ray photoelectron spectroscopy (XPS) on a Thermo Fisher-VG ESCALAB 250 X-ray photoelectron spectrometer. The excitation source was AlKα X-rays with a monochromatic power of 150 W. The charging effect was corrected for by the Al 2p peak (74.7 eV) of the support Al2O3 or the Si2p peak (103.6 eV) of SiO2. The reduction conditions were: heating rate 5 °C / min, pure H2 gas, reaction pressure 0.12 MPa, and reduction for 3 h after heating to the target temperature.

[0074] Example 1

[0075] Dissolve 20g of P123 in 300mL of anhydrous ethanol with vigorous stirring. Add 30g of aluminum isopropoxide and 33.6g of 67wt% nitric acid solution to the above solution and stir for 1 hour to obtain the first solution. Add 10g of P123, 6.37g of ferric nitrate nonahydrate, 6.27g of ferrous chloride tetrahydrate, 0.124g of copper nitrate trihydrate, and 0.785g of nickel nitrate hexahydrate to 150mL of anhydrous ethanol and stir for 1 hour to obtain the second solution.

[0076] The second solution was mixed with the first solution and stirred for 8 hours to obtain a gel. The gel was then stored in a 120°C oven for 48 hours to evaporate the solvent. The gel was then calcined at 400°C for 5 hours to obtain catalyst A1. The catalyst A1 was then pressed into tablets at 15 MPa, crushed, and sieved through a 40-60 mesh screen for reaction evaluation.

[0077] The morphology of the catalyst was characterized by TEM, such as Figure 1 As shown, the active metal in the catalyst maintains a small grain size. The elemental composition of the catalyst surface was determined by XPS analysis. The XPS curves and Fe 2p peak fractionation results are shown below. Figure 2 As shown, the catalyst surface contains both ferrous and ferric iron.

[0078] The physicochemical characteristics of the tested catalysts are listed in Table 1 and Table 1 (continued).

[0079] Example 2

[0080] Dissolve 10g of P123 in 200mL of anhydrous ethanol with vigorous stirring. Add 17.8g of aluminum isopropoxide and 22.4g of 67wt% nitric acid solution to the above solution and stir for another 1h to obtain the first solution. Add 10g of P123, 4.13g of ferric nitrate nonahydrate, 4.07g of ferrous chloride tetrahydrate, 0.08g of copper nitrate trihydrate, and 1.23g of chromium nitrate nonahydrate to 150mL of anhydrous ethanol and stir for 1h to obtain the second solution.

[0081] The second solution was mixed with the first solution and stirred for 5 hours to obtain a gel. The gel was then stored in a 120°C oven for 48 hours to evaporate the solvent. It was then calcined at 400°C for 5 hours to obtain catalyst A2. The catalyst A2 was compressed into tablets at 15 MPa, crushed, and sieved through a 40-60 mesh screen for reaction evaluation.

[0082] Catalyst morphology and Figure 1 Similarly, XPS testing of the catalyst surface elemental composition revealed that the catalyst surface contains ferrous and ferric iron.

[0083] The physicochemical characteristics of the tested catalysts are listed in Table 1 and Table 1 (continued).

[0084] Example 3

[0085] Dissolve 10g of P123 in 100mL of anhydrous ethanol with vigorous stirring. Add 10g of aluminum isopropoxide and 11.2g of 67wt% nitric acid solution to the above solution and stir for 1 hour to obtain the first solution. Add 5g of P123, 2.03g of ferric nitrate nonahydrate, 2g of ferrous chloride tetrahydrate, and 0.08g of copper nitrate trihydrate to 50mL of anhydrous ethanol and stir for 1 hour to obtain the second solution.

[0086] The second solution was mixed with the first solution and stirred for 5 hours to obtain a gel. The gel was then stored in a 120°C oven for 48 hours to evaporate the solvent. It was then calcined at 400°C for 5 hours to obtain catalyst A3. The catalyst A3 was then pressed into tablets at 15 MPa, crushed, and sieved through a 40-60 mesh screen for reaction evaluation.

[0087] The physicochemical characteristics of the tested catalysts are listed in Table 1 and Table 1 (continued).

[0088] Example 4

[0089] The method was followed in Example 1, except that the mass of ferric nitrate nonahydrate was 12 g and the mass of ferrous chloride tetrahydrate was 5.91 g in the second solution. Catalyst A4 was obtained. It was pressed into tablets at 15 MPa, crushed, and sieved through a 40-60 mesh screen for reaction evaluation.

[0090] The physicochemical characteristics of the tested catalysts are listed in Table 1 and Table 1 (continued).

[0091] Example 5

[0092] Following the method of Example 1, except that the mass of copper nitrate trihydrate in the second solution was 0.76 g and the mass of nickel nitrate hexahydrate was 0.688 g, resulting in catalyst A. Catalyst A was pressed into tablets at 15 MPa, crushed, and sieved through a 40-60 mesh screen for reaction evaluation.

[0093] The physicochemical characteristics of the tested catalysts are listed in Table 1 and Table 1 (continued).

[0094] Example 6

[0095] The method was followed as in Example 1, except that the gel was stored in a 40°C incubator for 120 hours to evaporate the solvent. It was then calcined at 400°C for 5 hours to obtain catalyst A6. The catalyst A6 was then pressed into tablets at 15 MPa, crushed, and sieved through a 40-60 mesh screen for reaction evaluation.

[0096] The physicochemical characteristics of the tested catalysts are listed in Table 1 and Table 1 (continued).

[0097] Comparative Example 1

[0098] Solution A was prepared by dissolving 20g of ferric nitrate nonahydrate, 0.72g of nickel nitrate hexahydrate, 0.60g of copper nitrate trihydrate, and 0.5g of P123 (5800) in 100mL of ethanol and 50mL of deionized water. Solution B was prepared by dissolving 30g of ammonia (25%–28% by mass) in 50mL of ethanol and 20mL of deionized water. Solution B was added to solution A via a peristaltic pump at a rate of 5mL / min, stirred for 4 hours, and then stored in a constant temperature oven at 120℃ for 48 hours to allow the solvent to evaporate. The solution was then calcined at 400℃ for 5 hours to obtain catalyst DA1. The catalyst was then pressed into tablets at 15MPa, crushed, and sieved through a 40–60 mesh screen for reaction evaluation.

[0099] The elemental composition of the catalyst surface was tested by XPS. The catalyst surface contained only ferric iron. The physicochemical characteristics of the catalyst are listed in Table 1 and Table 1 (continued).

[0100] Comparative Example 2

[0101] 10 g of P123 was dissolved in 200 mL of anhydrous ethanol with vigorous stirring. 22.4 g of a 67 wt% nitric acid solution, 12.4 g of ferric nitrate nonahydrate, 0.1 g of copper nitrate trihydrate, and 1.1 g of chromium nitrate nonahydrate were added to the solution and stirred for 5 hours until homogeneous. The mixture was then stored in a 120°C incubator for 48 hours to allow the solvent to evaporate. The solution was calcined at 400°C for 5 hours to obtain catalyst DA2. This was then pressed into tablets at 15 MPa, crushed, and sieved through a 40-60 mesh screen for reaction evaluation.

[0102] The elemental composition of the catalyst surface was tested by XPS. The catalyst surface contained only ferric iron. The physicochemical characteristics of the catalyst are listed in Table 1 and Table 1 (continued).

[0103] Comparative Example 3

[0104] Solution A was prepared by dissolving 20g of ferric nitrate nonahydrate, 54.12g of aluminum nitrate nonahydrate, 0.60g of copper nitrate trihydrate, and 0.5g of P123 (5800) in 100mL of ethanol and 50mL of deionized water. Solution B was prepared by dissolving 30g of ammonia (25%–28% by mass) in 50mL of ethanol and 20mL of deionized water. Solution B was added to solution A via a peristaltic pump at a rate of 5mL / min, stirred for 4 hours, and then stored in a constant temperature oven at 120℃ for 48 hours to allow the solvent to evaporate. The solution was then calcined at 400℃ for 5 hours to obtain catalyst DA3. The catalyst was then pressed into tablets at 15MPa, crushed, and sieved through a 40–60 mesh screen for reaction evaluation.

[0105] The elemental composition of the catalyst surface was tested by XPS. The catalyst surface contained only ferric iron. The physicochemical characteristics of the catalyst are listed in Table 1 and Table 1 (continued).

[0106] Table 1

[0107]

[0108] Continued from Table 1

[0109]

[0110] Test case

[0111] The following test examples illustrate the catalytic performance of the catalyst of the present invention in the water-gas shift reaction.

[0112] (1) The catalysts prepared in the examples and comparative examples need to be pretreated at 400°C for 2 hours before evaluation. The pretreatment is carried out under normal pressure and a dry gas atmosphere. The composition of the dry gas atmosphere is as follows (volume content): CO / CO2 / H2 / N2 = 24.7% / 8.3% / 49.5% / 17.5%, and the dry gas space velocity is 20000h. -1 The water-to-carbon ratio is 3.5.

[0113] Weigh 0.5g of the pretreated catalyst and load it into a reaction tube with an inner diameter of 8mm. The dry gas space velocity is 16000h. -1 The water-to-carbon ratio was 2.4. The reaction was carried out at atmospheric pressure and 400℃ for 2 hours. The composition of the product was analyzed by phase chromatography, the hydrogen production rate was calculated, and the evaluation results are shown in Table 2.

[0114] in,

[0115]

[0116]

[0117] In the above formula, F CO(进) This refers to the CO flow rate at the reactor inlet, F CO(出) This refers to the CO flow rate (mL / min) at the reactor outlet, F CH4(进) This refers to the CH4 flow rate (mL / min) at the reactor inlet. CH4(出) This refers to the CH4 flow rate (mL / min) at the reactor outlet. H2(进) This refers to the H2 flow rate (mL / min) at the reactor inlet, F H2(出) This refers to the H2 flow rate (mL / min) at the reactor outlet, V m M is the molar volume of the gas (L / mol). cat The mass (g) of the catalyst loaded.

[0118] (2) The catalysts prepared in the above examples and comparative examples were subjected to heat resistance activity tests.

[0119] The conditions for the heat resistance activity test are: the atmosphere, space velocity and water vapor shift reaction conditions are the same, the temperature is maintained at 530℃ for 6 hours, and then the temperature is lowered to 400℃ for 4 hours to equilibrate. The CO conversion rate is then tested to determine the heat resistance activity.

[0120] The activity retention rate after heat resistance was then calculated using the following formula, and the results are shown in Table 2.

[0121] The initial activity is the CO conversion rate measured under the conditions of test example (1).

[0122] Table 2

[0123]

[0124] Combining the results in Tables 1, 1 (continued), and 2, it can be seen that, compared with the comparative example, the catalyst prepared in this embodiment of the invention, through the synergistic effect of the introduction of auxiliary agents with both ferrous and ferric sources, exhibits a suitable Fe content on its surface. 2+ / Fe 3+ The formula is suitable for low water-to-gas ratio conditions, exhibiting high CO conversion and hydrogen production rates under high space velocities. It also demonstrates good heat resistance and high activity retention after high-temperature treatment. By controlling the gel drying temperature, the resulting catalyst has a large total pore volume and a small average pore size, which is beneficial for stabilizing the catalyst structure, improving its thermal stability, enhancing its catalytic activity, and increasing the hydrogen production rate.

[0125] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A water-gas shift catalyst, characterized in that, The catalyst comprises alumina, active elements, and auxiliary elements; the auxiliary elements comprise Cu, Ni, and / or Cr; the active elements comprise ferrous iron and ferric iron, and the atomic ratio of ferrous iron to ferric iron on the catalyst surface is 0.64-1 as determined by XPS. In the auxiliary elements, the molar ratio of Cu to the total molar ratio of Ni and / or Cr is 0.1-0.19; The total pore volume of the catalyst is 0.3-0.5 mL / g; The catalyst has an average pore size of 8-12 nm; Based on the mass of the catalyst, the alumina content is 61.95-80 wt%; the active element content (calculated as oxide) is 20-34.23 wt%; and the auxiliary element content (calculated as oxide) is 0.1-3.26 wt%.

2. The catalyst according to claim 1, wherein, The atomic ratio of ferrous iron to ferric iron on the catalyst surface was determined to be 0.64-0.8 by XPS.

3. The catalyst according to claim 1, wherein, Based on the mass of the catalyst, the alumina content is 61.95-70 wt%; the active element content (calculated as oxide) is 30-34.23 wt%; and the auxiliary element content (calculated as oxide) is 1-3.26 wt%.

4. The catalyst according to claim 1, wherein, The molar ratio of the active element to the auxiliary element is 1-50:

1.

5. The catalyst according to claim 4, wherein, The molar ratio of the active element to the auxiliary element is 5-20:

1.

6. A method for preparing a water-gas shift catalyst according to any one of claims 1-5, comprising the following steps: (1) In the presence of the first dispersant, aluminum isopropoxide, the first template agent and acid are mixed to obtain the first solution; (2) In the presence of a second dispersant, a ferrous iron source, a ferric iron source, a soluble compound containing an auxiliary element, and a second template agent are mixed to obtain a second solution; wherein, based on iron element, the molar ratio of the ferrous iron source to the ferric iron source is 1-3:1; the auxiliary element is selected from Cu, as well as Ni and / or Cr; among the auxiliary elements, the molar amount of Cu to the total molar amount of Ni and / or Cr is 0.1-0.19; (3) Under stirring conditions, the first solution and the second solution are mixed to obtain a gel; (4) The gel is dried and calcined; The amounts of the first and second solutions are such that the alumina content is 61.95-80 wt%; the active element content (calculated as oxide) is 20-34.23 wt%; and the auxiliary element content (calculated as oxide) is 0.1-3.26 wt%.

7. The preparation method according to claim 6, wherein, The first template agent and the second template agent are each independently selected from at least one of the following: hexadecyltrimethylammonium bromide, polyoxyethylene / polyoxypropylene / polyoxyethylene amphiphilic block copolymer, polyethylene oxide-polyoxypropylene-polyoxyethylene triblock copolymer, polyoxyethylene-polyoxypropylene block polyether, polyethylene glycol, and polyoxyethylene ether.

8. The preparation method according to claim 6, wherein, In step (1), the mass ratio of the first template agent to aluminum isopropoxide is 0.1-1:

1.

9. The preparation method according to claim 8, wherein, In step (1), the mass ratio of the first template agent to aluminum isopropoxide is 0.2-0.8:

1.

10. The preparation method according to claim 6, wherein, The mass ratio of aluminum isopropoxide to acid is 0.1-10:

1.

11. The preparation method according to claim 10, wherein, The mass ratio of aluminum isopropoxide to acid is 1-5:

1.

12. The preparation method according to claim 6, wherein, The acid is citric acid and / or nitric acid.

13. The preparation method according to claim 6, wherein, The amount of the first dispersant used is such that the concentration of aluminum isopropoxide in the first solution is 0.05-1 g / mL.

14. The preparation method according to claim 13, wherein, The amount of the first dispersant is such that the concentration of aluminum isopropoxide in the first solution is 0.1-0.5 g / mL.

15. The preparation method according to claim 6, wherein, The molar ratio of divalent iron source to trivalent iron source is 1.5-2.5:1, based on iron element content.

16. The preparation method according to claim 6, wherein, The mass ratio of the second template agent to the first template agent is 0.1-1:

1.

17. The preparation method according to claim 6, wherein, The ratio of the total molar amount of the divalent iron source and the trivalent iron source to the molar amount of the soluble compound containing the auxiliary element, calculated by metallic elements, is 1-50:

1.

18. The preparation method according to claim 17, wherein, The ratio of the total molar amount of the divalent iron source and the trivalent iron source to the molar amount of the soluble compound containing the auxiliary element, calculated by metallic elements, is 1-5:

1.

19. The preparation method according to claim 6, wherein, The divalent iron source, trivalent iron source, and soluble compound containing auxiliary elements are each independently selected from inorganic and / or organic salts of metals.

20. The preparation method according to claim 19, wherein, The ferrous iron source, the ferric iron source, and the soluble compound containing the auxiliary element are each independently at least one of nitrate, sulfate, halide, acetate, and formate.

21. The preparation method according to claim 6, wherein, The stirring time in step (3) is 1-10 hours.

22. The preparation method according to claim 21, wherein, The stirring time in step (3) is 3-6 hours.

23. The preparation method according to claim 6, wherein, The amounts of the first and second solutions are such that, based on the total amount of the catalyst obtained, the alumina content is 61.95-70 wt%; the active element content (calculated as oxide) is 30-34.23 wt%; and the auxiliary element content (calculated as oxide) is 1-3.26 wt%.

24. The preparation method according to claim 6, wherein, The drying temperature in step (4) shall not be lower than 90°C; the drying time shall be 12-84h.

25. The preparation method according to claim 24, wherein, The drying temperature in step (4) is 100-150℃; the drying time is 24-72h.

26. The preparation method according to claim 25, wherein, The drying temperature in step (4) is 110-130℃.

27. The preparation method according to claim 6, wherein, The calcination conditions include: a calcination temperature of 300-500℃ and a calcination time of 2-8 hours.

28. The application of the water-gas shift catalyst according to any one of claims 1-5 or the water-gas shift catalyst prepared by any one of claims 6-27 in the water-gas shift reaction.

29. A method for a water vapor shift reaction, characterized in that, include: Under the conditions of water-gas shift reaction, CO-containing feed gas and water vapor are contacted with the catalyst to carry out water-gas shift reaction; The catalyst is the water-gas shift catalyst according to any one of claims 1-5 or the water-gas shift catalyst prepared by the preparation method according to any one of claims 6-27.

30. The method according to claim 29, wherein, The conditions for the water-gas shift reaction include: a reaction temperature of 300-500℃; a reaction pressure of 0.1-5MPa; and a mass hourly space velocity (MSV) of 5000-20000 h⁻¹. -1 The water-to-carbon ratio is 2.4-4.

31. The method according to claim 30, wherein, The conditions for the water-gas shift reaction include: a reaction temperature of 350-450℃; a reaction pressure of 1-2 MPa; and a mass hourly space velocity (MSV) of 10000-18000 h⁻¹ for the feed gas. -1 The water-to-carbon ratio is 2.8-3.5.

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