A sulfur-tolerant shift catalyst, its preparation method and application

Abstract

The application belongs to the technical field of catalysts, and particularly relates to a sulfur-tolerant shift catalyst, and further discloses a preparation method and application thereof. The sulfur-tolerant shift catalyst has a special catalyst Al2O3-MgAl2O4-CoAl2O4 carrier structure, high shift reaction activity, and low methanation reaction activity, and can effectively solve the problems of the decrease of shift reaction activity, the increase of methanation reaction activity, and the "temperature runaway" of the catalyst bed layer temperature caused by the methanation side reaction of the high CO content and low water-gas ratio process conditions.

Description

Technical Field

[0001] This invention belongs to the field of catalyst technology, specifically relating to a sulfur-resistant shift catalyst, and further discloses its preparation method and application. Background Technology

[0002] Currently, carbon monoxide shift conversion technology is mainly used in industrial production such as hydrogen production, methanol synthesis, ammonia synthesis, gasoline synthesis, and city gas production. Shift catalysts play a crucial role in these processes. Due to the shortage and rising price of crude oil, high-sulfur substances such as coal, residual oil, and petroleum coke have gradually gained attention as alternative feedstocks for light hydrocarbons. Furthermore, the development and advancement of residual oil and coal gasification processes, particularly the large-scale industrial application of pressurized coal-water slurry gasification technology, have further promoted the research and development of sulfur-resistant shift catalysts. Since the 1960s, cobalt-molybdenum based sulfur-resistant shift catalysts have been widely used due to their wide temperature range, sulfur resistance, and high activity in the CO shift reaction.

[0003] With the continuous improvement of residual oil and coal gasification processes, especially the large-scale industrial application of new pressurized gasification technologies, the CO content in the effective gas composition of process gas is increasing. Under high CO content and low water-to-gas ratio process conditions, when the catalyst bed temperature exceeds 350℃, methanation side reactions usually occur. This reaction releases a large amount of heat, causing a sharp increase in bed temperature, which further exacerbates the methanation side reaction. This not only reduces the hydrogen content of the product, leading to the safety risk of overheating in the unit, but also affects the activity and stability of the catalyst. In recent years, sulfur-resistant shift conversion processes have mainly relied on adjusting process parameters to suppress the occurrence of methanation side reactions, such as adopting high water-to-gas ratio shift conversion processes and increasing the water-to-gas ratio while cooling water, but the overall effectiveness has been minimal.

[0004] Studies show that spinel-type composite oxides AB₂O₄ possess advantages such as stable crystal structure, high surface activity, and ease of interaction with gases. In recent years, CoAl₂O₄, due to its unique structure and resulting special properties, has been widely used in research. For example, Chinese patent CN1981927A discloses a cobalt-based Fischer-Tropsch synthesis catalyst and its preparation method, which maintains high reactivity while exhibiting better C₅... +While selective, its application in cobalt-molybdenum sulfur-resistant shift catalysts remains unstudied. Furthermore, cobalt-molybdenum sulfur-resistant shift catalysts often use MgAl2O4 modified catalysts with Al2O3 support. For example, Chinese patent CN104971731A discloses a wide-temperature sulfur-resistant shift catalyst and its preparation method, using the calcined product of magnesium aluminum hydrotalcite as the support for the shift catalyst, achieving a CO conversion rate of 87.62%. Another example is Chinese patent CN110314675A, which discloses a modified alumina-based magnesium aluminum spinel, its preparation method, and a sulfur-resistant shift catalyst. Although this catalyst overcomes the drawback of easy hydrolysis and exhibits good activity and stability within a temperature range of 200-500℃, it still cannot reduce the selectivity of the methanation reaction under high-temperature, low-water-gas ratio conditions.

[0005] In summary, the field looks forward to developing a sulfur-resistant shift catalyst with high shift reaction activity and low methanation reaction activity, which would be of great significance for the development of carbon monoxide shift reaction technology. Summary of the Invention

[0006] Therefore, the technical problem to be solved by the present invention is to provide a sulfur-resistant shift catalyst, wherein the catalyst has high shift reaction activity and low methanation reaction activity;

[0007] The second technical problem to be solved by the present invention is to provide a method for preparing the sulfur-resistant shift catalyst;

[0008] The third technical problem to be solved by the present invention is to provide the application of the sulfur-resistant conversion catalyst in the carbon monoxide conversion process.

[0009] To solve the above-mentioned technical problems, the present invention provides a sulfur-resistant conversion catalyst, wherein the catalyst has a support structure as shown in Al2O3-MgAl2O4-CoAl2O4;

[0010] The sulfur-resistant shift catalyst comprises, by total amount: 6-12 wt% MoO3, 3-4 wt% CoO, 10-25 wt% MgO, 57-80 wt% Al2O3, and 2-10 wt% metal auxiliary oxides.

[0011] Specifically, in the sulfur-resistant conversion catalyst, the metal auxiliary oxide includes at least one of K2O, Zr2O, or Ti2O.

[0012] This invention also discloses a method for preparing a sulfur-resistant shift catalyst, comprising the following steps:

[0013] (1) Mix aluminum salt, cobalt salt and acid solution, and add alcohol solution to dissolve them to obtain a mixed solution for later use;

[0014] (2) Mix boehmite and magnesium oxide to obtain a mixture for later use;

[0015] (3) The mixture and the mixture are kneaded and shaped to obtain a carrier precursor, which is then subjected to a first drying and a first calcination treatment to obtain a catalyst carrier;

[0016] (4) The catalyst support is immersed in an active solution containing molybdenum salt and metal additive precursor, and then subjected to a second drying and a second calcination treatment to obtain the desired catalyst.

[0017] Specifically, in the preparation method of the sulfur-resistant shift catalyst, in step (1), the cobalt salt (in Co...) 2+ (calculated) and the aluminum salt (in Al) 3+ The molar ratio of (calculated) is 1:2-3.

[0018] Specifically, in the preparation method of the sulfur-resistant shift catalyst, in step (1), the acid solution reacts with the cobalt salt (in the form of Co). 2+ (calculated) and the aluminum salt (in Al) 3+ The molar ratio of the total amount of (calculated) is 1:0.5-1.5, preferably 1:1;

[0019] Preferably, the acid solution includes citric acid.

[0020] Specifically, in the preparation method of the sulfur-resistant shift catalyst, in step (1), the alcohol solution includes an aqueous ethanol solution;

[0021] Preferably, step (1) further includes the step of evaporating and concentrating the mixture.

[0022] Specifically, in the preparation method of the sulfur-resistant shift catalyst, in step (2), the magnesium oxide (in Mg) 2+ (calculated) and the pseudoboehmite (in Al) 3+ The molar ratio of (calculated) is 1:2-3.

[0023] Specifically, in the preparation method of the sulfur-resistant conversion catalyst, in step (3), the temperature of the first calcination step is 600-800℃, and the calcination time is 4-6h;

[0024] Preferably, the first drying temperature is 60-100℃ and the drying time is 10-15h.

[0025] Specifically, in the preparation method of the sulfur-resistant shift catalyst, in step (4), the molybdenum salt (in Mo...) 3+ (calculated) and the cobalt salt (in Co) 2+ The molar ratio of (calculated) is 2-3:1;

[0026] Preferably, the molybdenum salt comprises ammonium molybdate;

[0027] Preferably, the metal additive precursor includes a nitrate of a metal additive, more preferably one of potassium nitrate, zirconium nitrate, or metatitanic acid.

[0028] Specifically, in the preparation method of the sulfur-resistant conversion catalyst, in step (4), the temperature of the second calcination step is 400-600℃, and the calcination time is 2-4h;

[0029] Preferably, the second drying temperature is 60-100℃ and the drying time is 10-15h.

[0030] The present invention also discloses the application of the sulfur-resistant shift catalyst or the sulfur-resistant shift catalyst prepared by the method in the carbon monoxide shift process.

[0031] The sulfur-resistant shift catalyst of this invention has a special catalyst support structure of Al2O3-MgAl2O4-CoAl2O4. CoAl2O4 can form a catalytic reaction layer with the active component Mo, producing a strong synergistic effect. This enhances the electronic interaction between molybdenum and CoAl2O4, resulting in an H2 reduction peak of MoO3 between 515℃ and 520℃, while the catalyst exhibits H2 reduction peaks of both CoAl2O4 and MoO3 between 820℃ and 830℃. Simultaneously, the addition of metal promoters can synergistically constrain and stabilize Mo in the reaction in the presence of CoAl2O4, inhibiting Mo reduction, reducing the catalyst's adsorption of hydrogen, and improving the shift reaction activity while reducing the methanation reaction activity.

[0032] The sulfur-resistant shift catalyst of this invention has high shift reaction activity and low methanation reaction activity. It can effectively solve the adverse effects of high CO content and low water-to-gas ratio process conditions, such as high catalyst bed temperature and methanation side reaction, which lead to reduced shift reaction activity, increased methanation reaction activity, and "runaway" bed temperature. Attached Figure Description

[0033] To make the content of this invention easier to understand, the invention will be further described in detail below with reference to specific embodiments and accompanying drawings, wherein...

[0034] Figure 1 The images show the H2-TPR spectra of the catalysts in Example 1 and Comparative Example 1. Detailed Implementation

[0035] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention.

[0036] Example 1

[0037] The preparation method of the sulfur-resistant shift catalyst described in this embodiment includes the following steps:

[0038] (1) Take 25.7g of aluminum nitrate, 12g of cobalt nitrate and 20.8g of citric acid and pour them into a beaker. Add an aqueous solution of ethanol to dissolve them completely to obtain a mixture. Stir and evaporate the mixture in an aqueous solution at 80℃ to a certain volume.

[0039] (2) Take 78.6g of boehmite and 15g of magnesium oxide and mix them evenly to obtain a mixture;

[0040] (3) The mixture and the material are kneaded and shaped (kneaded into a column shape, diameter) A strip-shaped catalyst support precursor was prepared, dried in an oven at 80°C for 12 hours, and calcined in a muffle furnace at 700°C for 5 hours to obtain the catalyst support.

[0041] (4) Take 9.8g of ammonium molybdate, 5.7g of metatitanic acid, 4.28g of potassium nitrate and 14.0g of zirconium nitrate and dissolve them in deionized water. Then, impregnate the catalyst support with an equal volume of the solution. Dry the catalyst support at 80°C for 12 hours in an oven and calcine it at 500°C for 3 hours in a muffle furnace to obtain the desired catalyst.

[0042] Example 2

[0043] The preparation method of the sulfur-resistant shift catalyst described in this embodiment includes the following steps:

[0044] (1) Take 44.0g of aluminum nitrate, 16.0g of cobalt nitrate and 32.8g of citric acid and pour them into a beaker. Add an aqueous solution of ethanol to dissolve them completely to obtain a mixture. Stir and evaporate the mixture in an aqueous solution at 80℃ to a certain volume.

[0045] (2) Take 62.9g of boehmite and 20.0g of magnesium oxide and mix them evenly to obtain a mixture;

[0046] (3) Mix the mixture with the material and knead it into a column shape (diameter...). A strip-shaped catalyst support precursor was prepared, dried in an oven at 80°C for 12 hours, and calcined in a muffle furnace at 700°C for 5 hours to obtain the catalyst support.

[0047] (4) Take 14.6g of ammonium molybdate and 11.4g of metatitanic acid and dissolve them in deionized water. Impregnate the catalyst support with an equal volume of the solution, dry it in an oven at 80°C for 12 hours, and calcine it in a muffle furnace at 500°C for 3 hours to obtain the desired catalyst.

[0048] Example 3

[0049] The preparation method of the sulfur-resistant shift catalyst described in this embodiment includes the following steps:

[0050] (1) Take 36.7g of aluminum nitrate, 14g of cobalt nitrate and 27.8g of citric acid and pour them into a beaker. Add an aqueous solution of ethanol to dissolve them completely to obtain a mixture. Stir and evaporate the mixture in an aqueous solution at 80℃ to a certain volume.

[0051] (2) Take 78.6g of boehmite and 15g of magnesium oxide and mix them evenly to obtain a mixture;

[0052] (3) Mix the mixture with the material and knead it into a column shape (diameter...). A strip-shaped catalyst support precursor was prepared, dried in an oven at 80°C for 12 hours, and calcined in a muffle furnace at 700°C for 5 hours to obtain the catalyst support.

[0053] (4) Take 10.4g of ammonium molybdate, 5.7g of metatitanic acid and 14.0g of zirconium nitrate and dissolve them in deionized water. Impregnate the catalyst support with an equal volume of the solution, dry it in an oven at 80°C for 12 hours, and calcine it in a muffle furnace at 500°C for 3 hours to obtain the desired catalyst.

[0054] Example 4

[0055] The preparation method of the sulfur-resistant shift catalyst described in this embodiment includes the following steps:

[0056] (1) Take 25.7g of aluminum nitrate, 12g of cobalt nitrate and 20.8g of citric acid and pour them into a beaker. Add an aqueous solution of ethanol to dissolve them completely. Stir the mixture in an aqueous solution at 80℃ and evaporate it to a certain volume.

[0057] (2) Take 84.3g of boehmite and 15g of magnesium oxide and mix them evenly;

[0058] (3) Mix the mixture with the material and knead it into a column shape (diameter...). A strip-shaped catalyst support precursor was prepared, dried in an oven at 80°C for 12 hours, and calcined in a muffle furnace at 700°C for 5 hours to obtain the catalyst support.

[0059] (4) Dissolve 9.8g of ammonium molybdate, 5.7g of metatitanic acid and 4.28g of potassium nitrate in deionized water, and impregnate the catalyst support with an equal volume of the solution. Dry the catalyst in an oven at 80°C for 12 hours and calcine it in a muffle furnace at 500°C for 3 hours to obtain the catalyst.

[0060] Example 5

[0061] The preparation method of the sulfur-resistant shift catalyst described in this embodiment includes the following steps:

[0062] (1) Take 25.6g of aluminum nitrate, 12g of cobalt nitrate and 20.8g of citric acid and pour them into a beaker. Add an aqueous solution of ethanol to dissolve them completely. Stir the mixture in an aqueous solution at 80℃ and evaporate it to a certain volume.

[0063] (2) Take 77.1g of boehmite and 20g of magnesium oxide and mix them evenly;

[0064] (3) Mix the mixture with the material and knead it into a column shape (diameter...). A strip-shaped catalyst support precursor was prepared, dried in an oven at 80°C for 12 hours, and calcined in a muffle furnace at 700°C for 5 hours to obtain the catalyst support.

[0065] (4) Dissolve 9.8g of ammonium molybdate and 11.4g of metatitanic acid in deionized water, impregnate the catalyst support with an equal volume of the solution, dry in an oven at 80°C for 12h, and calcine in a muffle furnace at 500°C for 3h to obtain the catalyst.

[0066] Example 6

[0067] The preparation method of the sulfur-resistant shift catalyst described in this embodiment includes the following steps:

[0068] (1) Take 44g of aluminum nitrate, 16g of cobalt nitrate and 32.8g of citric acid and pour them into a beaker. Add an aqueous solution of ethanol to dissolve them completely. Stir the mixture in an aqueous solution at 80℃ and evaporate it to a certain volume.

[0069] (2) Take 61.4g of boehmite and 25g of magnesium oxide and mix them evenly;

[0070] (3) Mix the mixture with the material and knead it into a column shape (diameter...). A strip-shaped catalyst support precursor was prepared, dried in an oven at 80°C for 12 hours, and calcined in a muffle furnace at 700°C for 5 hours to obtain the catalyst support.

[0071] (4) Dissolve 9.8g of ammonium molybdate and 11.4g of metatitanic acid in deionized water, impregnate the catalyst support with an equal volume of the solution, dry in an oven at 80°C for 12h, and calcine in a muffle furnace at 500°C for 3h to obtain the catalyst.

[0072] Comparative Example 1

[0073] The preparation method of the catalyst described in this comparative example includes the following steps:

[0074] (1) Take 87.1g of boehmite, 20g of magnesium oxide and 11.42g of metatitanic acid and mix them evenly. The mixture is kneaded and shaped to obtain a strip-shaped catalyst support precursor. It is dried in an oven at 80℃ for 12h and calcined in a muffle furnace at 700℃ for 5h to obtain a catalyst support.

[0075] (2) Dissolve 9.8g of ammonium molybdate and 12g of cobalt nitrate in deionized water, and impregnate the catalyst support with an equal volume of the solution. Dry the catalyst in an oven at 80°C for 12 hours and calcine it in a muffle furnace at 500°C for 3 hours to obtain the catalyst.

[0076] Comparative Example 2

[0077] The preparation method of the catalyst described in this comparative example includes the following steps:

[0078] (1) Take 91.4g of boehmite and 25g of magnesium oxide, mix them evenly, knead them into a strip-shaped catalyst support precursor, dry them in an oven at 80℃ for 12h, and calcine them in a muffle furnace at 700℃ for 5h to obtain the catalyst support.

[0079] (2) Dissolve 9.8g of ammonium molybdate and 12g of cobalt nitrate in deionized water, and impregnate the catalyst support with an equal volume of the solution. Dry the catalyst in an oven at 80°C for 12 hours and calcine it in a muffle furnace at 500°C for 3 hours to obtain the catalyst.

[0080] Experimental Example

[0081] 1. Catalyst active components

[0082] The active component ratios of the catalysts prepared in Examples 1-6 and Comparative Examples 1-2 of the present invention are detailed in Table 1 below.

[0083] Table 1 Catalyst formulations for Examples 1-6 and Comparative Examples 1-2

[0084]

[0085] 2. Catalyst activity

[0086] In this experimental example, the catalyst was loaded into the reactor, the feed gas was introduced, and the temperature was raised to the test conditions and maintained at those conditions for 30 minutes. Chromatography was then initiated, and the sample analysis time was 30 minutes, repeated three times. The average of the three data points was taken.

[0087] Test conditions: catalyst loading 5 mL, reactor inlet temperature 300℃, pressure 4.0 MPa, volumetric hourly space velocity 2000 h⁻¹ -1 The volume ratio of H2 to CO is 3:7.

[0088] CO conversion rate = (CO volume content before reaction - CO volume content after reaction) / (CO volume content before reaction * (1 + CO volume content after reaction / 100)) × 100%.

[0089] This experimental example uses an evaluation device at a pressure of 4.0 MPa, a water-to-air ratio of 0.3, and a gas hourly space velocity of 2000 h⁻¹. -1Under controlled conditions, with the inlet temperature of the device controlled at 300℃, the catalysts prepared in the above examples and comparative examples were subjected to pressure activity tests. The test results are shown in Table 2 below. The performance comparison results of the catalysts prepared in Example 1 and Comparative Example 1 are attached. Figure 1 As shown.

[0090] Table 2. Catalytic activity evaluation results of the catalyst products from Examples 1-4 and Comparative Examples 1-2.

[0091] catalyst CO conversion rate, % <![CDATA[CH4 content in the tail gas, %]]> Example 1 50.7％ 0.38％ Example 2 49.2％ 0.37％ Example 3 48.9％ 0.41％ Example 4 49.8％ 0.40％ Example 5 50.3％ 0.42％ Example 6 48.4％ 0.44％ Comparative Example 1 45.1％ 1.58％ Comparative Example 2 44.8％ 1.75％

[0092] It is evident that the cobalt-molybdenum sulfur-resistant shift catalyst of this invention has the advantages of high shift reaction activity and low methanation reaction activity. It can effectively solve the adverse effects of high CO content and low water-gas ratio process conditions, such as high catalyst bed temperature leading to methanation side reaction, resulting in reduced shift reaction activity, increased methanation reaction activity, and bed temperature runaway, and has good application value.

[0093] The embodiments of the present invention have been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only for the purpose of helping to understand the method and core ideas of the present invention. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of the present invention. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. A sulfur-resistant shift catalyst, characterized in that, The catalyst has a support structure as shown in Al2O3-MgAl2O4-CoAl2O4; The sulfur-resistant conversion catalyst comprises, by total amount: 6-12 wt% MoO3, 3-4 wt% CoO, 10-25 wt% MgO, 57-80 wt% Al2O3, and 2-10 wt% metal auxiliary oxide; the metal auxiliary oxide includes at least one of K2O, ZrO2, or TiO2.

2. A method for preparing the sulfur-resistant shift catalyst as described in claim 1, characterized in that, Includes the following steps: (1) Mix aluminum salt, cobalt salt and acid solution, and add alcohol solution to dissolve them to obtain a mixed solution for later use; (2) Take boehmite and magnesium oxide and mix them to obtain a mixture for later use; (3) The mixture and the mixture are kneaded and shaped to obtain a carrier precursor, which is then subjected to a first drying and a first calcination treatment to obtain a catalyst carrier; (4) The catalyst support is immersed in an active solution containing molybdenum salt and metal additive precursor, and then subjected to a second drying and a second calcination treatment to obtain the desired catalyst.

3. The method for preparing the sulfur-resistant shift catalyst according to claim 2, characterized in that, In step (1): The molar ratio of the cobalt salt to the aluminum salt is 1:2-3; and / or, The molar ratio of the acid solution to the total amount of the cobalt salt and the aluminum salt is 1:0.5-1.5; The cobalt salt is Co 2+ The aluminum salt is calculated to be Al 3+ count.

4. The method for preparing the sulfur-resistant shift catalyst according to claim 2 or 3, characterized in that, Step (1) also includes the step of evaporating and concentrating the mixture; The acid solution includes citric acid; The alcohol solution includes an aqueous solution of ethanol.

5. The method for preparing the sulfur-resistant shift catalyst according to claim 2, characterized in that, In step (2), the molar ratio of magnesium oxide to boehmite is 1:2-3, wherein the magnesium oxide is in the form of Mg... 2+ The pseudoboehmite is calculated to be Al 3+ count.

6. The method for preparing the sulfur-resistant shift catalyst according to claim 2, characterized in that, In step (3), the temperature of the first roasting step is 600-800℃ and the roasting time is 4-6h; The first drying temperature is 60-100℃, and the drying time is 10-15h.

7. The method for preparing the sulfur-resistant shift catalyst according to claim 2, characterized in that, In step (4), the molar ratio of the molybdenum salt to the cobalt salt is 2-3:1; wherein the molybdenum salt is in the form of Mo... 3+ The cobalt salt is calculated to be Co 2+ count; The molybdenum salt includes ammonium molybdate; The metal additive precursor includes the nitrate of the metal additive.

8. The method for preparing the sulfur-resistant shift catalyst according to claim 7, characterized in that, The metal additive precursor is one of potassium nitrate, zirconium nitrate, or metatitanic acid.

9. The method for preparing the sulfur-resistant shift catalyst according to claim 7 or 8, characterized in that, In step (4), the temperature of the second roasting step is 400-600℃ and the roasting time is 2-4h; The second drying temperature is 60-100℃, and the drying time is 10-15h.

10. The application of the sulfur-resistant shift catalyst according to claim 1 or the sulfur-resistant shift catalyst prepared by the method according to any one of claims 2-9 in the carbon monoxide shift process.

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