Sub-nanoscale cu-based medium temperature shift catalysts, methods of making and using the same

Abstract

This invention belongs to the field of catalysis technology, and specifically discloses a sub-nanometer-scale Cu-based intermediate-temperature shift catalyst and its preparation method. The Cu-based intermediate-temperature shift catalyst consists of 20%–30% of a composite oxide support, 30%–40% of Cu sub-nanometer particles supported on the composite oxide support, and 30%–40% of an active agent. Based on a composite oxide support with a specific composition, the preparation process utilizes an active agent, a surfactant, and calcination under a protective atmosphere to ensure that the support is loaded with fully dispersed Cu particles with a main particle size less than 2 nm as the active component. Utilizing the size effect, the two components work synergistically, ensuring high catalytic activity, excellent thermal stability, a wide active temperature range, and a long service life, while also improving the CO conversion rate in application. This Cu-based intermediate-temperature shift catalyst exhibits excellent performance in CO conversion reactions within a temperature range of 180℃–400℃.

Description

Technical Field

[0001] This invention belongs to the field of catalysis technology, specifically relating to a sub-nanometer scale Cu-based intermediate temperature shift catalyst and its preparation method, as well as the application of the Cu-based intermediate temperature shift catalyst in CO conversion reaction. Background Technology

[0002] In today's electronics and chemical industries, especially in the synthesis of ammonia and methanol, the demand for high-purity H2 is increasing. In recent years, shift reactions have been considered one of the most important hydrogen production processes because they can remove CO from syngas and produce additional H2.

[0003] Currently, water-gas shift catalysts mainly fall into three categories: iron-based high-temperature shift catalysts, copper-based low-temperature shift catalysts, and cobalt-molybdenum-based sulfur-resistant wide-temperature shift catalysts. With increasing demands for energy conservation and emission reduction, and advancements in process technology, higher requirements are being placed on the catalysts used. As an economical catalyst, how to achieve high thermal stability, long service life, and catalytic activity across a wide active temperature range for copper-based shift catalysts has become an important research topic.

[0004] While numerous studies on Cu-based conversion catalysts have achieved improvements in low-temperature activity, thermal stability, water resistance, and catalyst lifespan, problems still exist that affect catalytic activity, such as the tendency of Cu grains to sinter during preparation or application, or uneven particle size distribution. Examples include the research in Chinese patents CN 105214671A, CN103599779A, and CN 111482179A.

[0005] Therefore, how to further improve catalytic activity over a wide active temperature range while ensuring good thermal stability and service life is a problem that still needs further research. Summary of the Invention

[0006] To address the problems in existing Cu-based shift catalysts that affect catalytic activity, such as the tendency of Cu grains to sinter during preparation or application, or large particle size and / or uneven distribution, this invention provides a sub-nanometer-scale Cu-based intermediate-temperature shift catalyst and its preparation method. This Cu-based intermediate-temperature shift catalyst, by controlling the particle size of the Cu particles supported on the support to be less than 2 nm and highly dispersed, combined with the synergistic effect of the composite oxide support, exhibits excellent catalytic activity, high thermal stability, and a significantly extended service life.

[0007] The present invention specifically adopts the following technical solution:

[0008] A sub-nanometer-scale Cu-based intermediate-temperature shift catalyst comprises 20%–30% of a composite oxide support, 30%–40% of Cu sub-nanometer particles supported on the composite oxide support, and 30%–40% of an active agent, all by mass percentage; wherein at least 90% of the Cu sub-nanometer particles are less than 2 nm in size; the composite oxide support is a compound with an alkaline earth metal-AlO4 structure; and the active agent is selected from any one of ZnO, ZrO2, and K2O.

[0009] Furthermore, the composite oxide support is selected from any one of MgAlO4, CaAlO4, BaAlO4, and SrAlO4.

[0010] Furthermore, the composite oxide support is MgAlO4.

[0011] Furthermore, the specific surface area of ​​the composite oxide support is 200 m². 2 / g~220m 2 / g, and the water absorption rate is 60% to 80%.

[0012] Generally, composite oxide carriers have constructed geometric structures, such as pellets, foams, honeycomb, and monolithic materials.

[0013] Another object of the present invention is to provide a method for preparing the above-mentioned Cu-based intermediate temperature shift catalyst, which includes the following steps:

[0014] S1. Disperse the water-soluble salt of the active adjuvant ion in an alcohol solution to obtain the active adjuvant precursor solution; the active adjuvant ion is selected from Zn. 2+ Zr 4+ K + Any one of them;

[0015] S2. Mix the water-soluble salt of Cu with the surfactant evenly to obtain the precursor liquid of the active component;

[0016] S3. After thoroughly mixing the active component precursor liquid and the active auxiliary agent precursor liquid, add the composite oxide support, let stand, age, and then dry to obtain the catalyst precursor.

[0017] S4. The catalyst precursor is calcined at 380℃~400℃ for 4h~6h under a protective gas atmosphere, and then reduced with H2 at 200℃~250℃ for 4h~6h to obtain Cu-based medium-temperature conversion catalyst.

[0018] In step S1, generally, the mass concentration of the alcohol solution is 50wt% to 70wt%.

[0019] Furthermore, in the precursor fluid of the active component, Cu 2+The molar ratio of surfactant to active ingredient is 1:1 to 3.

[0020] Preferably, the surfactant is selected from at least one of hexadecyltrimethylammonium bromide, sodium dodecylbenzenesulfonate, and polyethylene glycol.

[0021] Water-soluble salts of Cu are used to provide a copper source for subsequent calcination and H2 reduction to prepare Cu sub-nano particles. Generally, water-soluble salts of Cu are selected from at least one of Cu(NO3)2, Cu(CH3CH2O)2, and CuSO4. Water-soluble salts of active agent ions are used to provide a corresponding metal source for subsequent calcination to prepare active agents. Generally, they are selected from at least one of nitrates, chlorides, acetates, and sulfates.

[0022] Further, in step S3, Cu in the precursor fluid of the active component 2+ The molar ratio of active adjuvant ions to those in the precursor fluid of the active adjuvant is 1:0.8 to 1.

[0023] Furthermore, in step S3, the specific surface area of ​​the composite oxide support is 200 m². 2 / g~220m 2 / g, water absorption rate is 60%~80%.

[0024] Furthermore, in step S3, after mixing the precursor fluid of the active component and the precursor fluid of the active adjuvant, the pH of the obtained mixture is maintained at 7 to 7.5, which is neutral or slightly alkaline.

[0025] Generally, in step S3, the drying conditions are: vacuum drying at 70℃~100℃ for 8h~12h.

[0026] Another object of the present invention is to provide the application of the above-mentioned Cu-based intermediate temperature shift catalyst in the CO shift reaction, which is applied in the temperature range of 180℃ to 400℃.

[0027] The beneficial effects of this invention are:

[0028] 1) The Cu-based intermediate-temperature shift catalyst provided by this invention is based on a composite oxide support with a specific composition, on which fully dispersed Cu particles with a main particle size of less than 2 nm are loaded as the active component. Utilizing the size effect, the two components work synergistically to ensure that the catalyst possesses the advantages of high catalytic activity, excellent thermal stability, a wide active temperature range, and a long service life, while also improving the CO conversion rate during application. Furthermore, by introducing active additives, the catalytic activity of the catalyst can be further improved, or structural adjustment can be performed to further reduce the agglomeration of the Cu sub-nanometer active component during long-term use or high-temperature processes, thereby enhancing anti-aging performance and extending service life.

[0029] 2) The preparation method of the Cu-based intermediate temperature shift catalyst provided by this invention, by selecting a specific composite oxide support, and by supplementing the preparation of Cu sub-nano particles with active additives, surfactants, and calcination under a protective atmosphere, not only ensures that the formed Cu sub-nano particles are highly dispersed and loaded on the surface of the composite oxide support, but also controls the size of most Cu sub-nano particles to below 2 nm. The extremely small particle size also improves its dispersibility, thereby effectively suppressing the sintering and agglomeration of Cu particles. This not only improves the catalytic activity, but also greatly extends the service life of the catalyst. Furthermore, the excellent dispersibility also improves the thermal stability of the catalyst, broadens the active temperature range, and ensures that it has excellent application performance in the temperature range of 180℃ to 400℃. Attached Figure Description

[0030] Figure 1 This is a TEM image of the Cu-based intermediate temperature shift catalyst according to Example 1 of the present invention;

[0031] Figure 2 This is a particle size distribution diagram of the catalyst according to Example 1 of the present invention;

[0032] Figure 3 This is an activity evaluation diagram of the catalysts of Example 1 and Comparative Example 1 according to the present invention at an inlet temperature of 280°C for 500 hours. Detailed Implementation

[0033] To better understand the present invention, the following examples are further illustrative of the invention and are only used to explain the content of the invention, but do not limit the invention. All similar embodiments based on the present invention should be within the scope of protection.

[0034] In the following embodiments, the specific surface area of ​​the MgAlO4 support used is 200 m². 2 / g~220m 2 / g (slight fluctuations between different batches); water absorption rates were 60%–63% (Examples 1, 3, and 4), 72%–73% (Example 2), and 77%–79% (Examples 5 and 6), respectively.

[0035] Example 1

[0036] First, 154g of Zn(NO3)2 was added to a 60wt% ethanol solution and ultrasonically dispersed for 5min to obtain the precursor fluid of the active adjuvant.

[0037] Next, 187.56g Cu(NO3)2 was added to an aqueous solution containing 356.16g SDBS, and the mixture was ultrasonically dispersed to obtain the precursor solution of the active component.

[0038] Next, under stirring conditions, the active component precursor liquid was first added to the active auxiliary agent precursor liquid, the pH of the system was kept at 7-7.5, and stirring was continued for 30 min. Then, 36 g of MgAlO4 was added to the obtained mixture. After standing and aging, it was dried under vacuum at 80 °C for 10 h to obtain the catalyst precursor.

[0039] Finally, the catalyst precursor was placed in a tube furnace under Ar atmosphere protection and calcined at 400°C for 6 hours, and then reduced with H2 at 220°C for 6 hours to obtain catalyst S1.

[0040] The catalyst S1 obtained in this embodiment consists of 21.7 wt% MgAlO4 support, 38.3 wt% Cu sub-nano particles supported thereon, and 40 wt% ZnO active agent.

[0041] TEM tests were performed on catalyst S1, such as... Figure 1 As shown. From Figure 1 As can be seen, numerous particles of sub-nanometer size are highly dispersed on the surface of the MgAlO4 support, including Cu particles, the active component of the catalyst.

[0042] Meanwhile, the particle size distribution of catalyst S1 was tested, such as... Figure 2 As shown. From Figure 2 As can be seen, the size of Cu sub-nano particles in this catalyst is mainly concentrated between 1 nm and 1.8 nm, and more than 90% of the particles are smaller than 2 nm, exhibiting extremely small particle size.

[0043] Example 2

[0044] First, 115g of Zn(NO3)2 was added to a 70wt% ethanol solution and ultrasonically dispersed for 5 minutes to obtain the precursor fluid of the active adjuvant.

[0045] Then, 117.56g Cu(NO3)2 was added to an aqueous solution containing 740.05g PEG400, and the mixture was ultrasonically dispersed to obtain the precursor solution of the active component.

[0046] Next, under stirring conditions, the active component precursor liquid was first added to the active auxiliary agent precursor liquid, the pH of the system was kept at 7-7.5, and stirring was continued for 30 min. Then, 35 g of MgAlO4 was added to the obtained mixture. After standing and aging, the catalyst precursor was obtained by vacuum drying at 80 °C for 10 h.

[0047] Finally, the catalyst precursor was placed in a tube furnace under Ar atmosphere protection and calcined at 380°C for 5 hours, and then reduced with H2 at 220°C for 5 hours to obtain catalyst S2.

[0048] The catalyst S2 obtained in this embodiment consists of 28.2 wt% MgAlO4 support, 32 wt% Cu sub-nano particles supported thereon, and 39.8 wt% ZnO active agent.

[0049] Example 3

[0050] First, 103.4g of Zn(NO3)2 was added to a 50wt% ethanol solution and ultrasonically dispersed for 5min to obtain the precursor fluid of the active adjuvant.

[0051] Then, 127.56g Cu(NO3)2 was added to an aqueous solution containing 249.97g CTAB, and the mixture was ultrasonically dispersed to obtain the precursor fluid of the active component.

[0052] Next, under stirring conditions, the active component precursor liquid was first added to the active auxiliary agent precursor liquid, the pH of the system was kept at 7-7.5, and stirring was continued for 30 min. Then, 36 g of MgAlO4 was added to the obtained mixture. After standing and aging, it was dried under vacuum at 80 °C for 10 h to obtain the catalyst precursor.

[0053] Finally, the catalyst precursor was placed in a tube furnace under Ar atmosphere protection and calcined at 390°C for 5 hours, and then reduced with H2 at 200°C for 5 hours to obtain catalyst S3.

[0054] The catalyst S3 obtained in this embodiment consists of 29.1 wt% MgAlO4 support, 35 wt% Cu sub-nano particles supported thereon, and 35.9 wt% ZnO active agent.

[0055] Example 4

[0056] First, 115g of Zn(NO3)2 was added to a 60wt% ethanol solution and ultrasonically dispersed for 5 minutes to obtain the precursor fluid of the active adjuvant.

[0057] Then, 117.56g Cu(NO3)2 was added to an aqueous solution containing 318.07g SDBS, and the mixture was ultrasonically dispersed to obtain the precursor fluid of the active component.

[0058] Next, under stirring conditions, the active component precursor liquid was first added to the active auxiliary agent precursor liquid, the pH of the system was kept at 7-7.5, and stirring was continued for 30 min. Then, 38 g of MgAlO4 was added to the obtained mixture. After standing and aging, the catalyst precursor was obtained by vacuum drying at 90℃ for 10 h.

[0059] Finally, the catalyst precursor was placed in a tube furnace under Ar atmosphere protection and calcined at 390°C for 4 hours, and then reduced with H2 at 250°C for 6 hours to obtain catalyst S4.

[0060] The catalyst S4 obtained in this embodiment consists of 29.9 wt% MgAlO4 support, 31.3 wt% Cu sub-nano particles supported thereon, and 38.8 wt% ZnO active agent.

[0061] Example 5

[0062] First, 106g of Zn(NO3)2 was added to a 60wt% ethanol solution and ultrasonically dispersed for 5min to obtain the precursor fluid of the active adjuvant.

[0063] Then, 117.56g Cu(NO3)2 was added to an aqueous solution containing 286.16g SDBS, and the mixture was ultrasonically dispersed to obtain the precursor fluid of the active component.

[0064] Next, under stirring conditions, the active component precursor liquid was first added to the active auxiliary agent precursor liquid, the pH of the system was kept at 7-7.5, and stirring was continued for 30 min. Then, 36 g of MgAlO4 was added to the obtained mixture. After standing and aging, it was dried under vacuum at 100 °C for 10 h to obtain the catalyst precursor.

[0065] Finally, the catalyst precursor was placed in a tube furnace under Ar atmosphere protection and calcined at 380°C for 4 hours, and then reduced with H2 at 200°C for 4 hours to obtain catalyst S5.

[0066] The catalyst S5 obtained in this embodiment consists of 29.7 wt% MgAlO4 support, 32.8 wt% Cu sub-nano particles supported thereon, and 37.5 wt% ZnO active agent.

[0067] Example 6

[0068] First, 106g of Zn(NO3)2 was added to a 60wt% ethanol solution and ultrasonically dispersed for 5min to obtain the precursor fluid of the active adjuvant.

[0069] Then, 117.56g Cu(NO3)2 was added to an aqueous solution containing 323.35g CTAB, and the mixture was ultrasonically dispersed to obtain the precursor fluid of the active component.

[0070] Next, under stirring conditions, the active component precursor liquid was first added to the active auxiliary agent precursor liquid, the pH of the system was kept at 7-7.5, and stirring was continued for 30 min. Then, 36 g of MgAlO4 was added to the obtained mixture. After standing and aging, it was dried under vacuum at 80 °C for 10 h to obtain the catalyst precursor.

[0071] Finally, the catalyst precursor was placed in a tube furnace under Ar atmosphere protection and calcined at 400°C for 6 hours, and then reduced with H2 at 250°C for 4 hours to obtain catalyst S6.

[0072] The catalyst S6 obtained in this embodiment consists of 29.7 wt% MgAlO4 support, 32.8 wt% Cu sub-nano particles supported thereon, and 37.5 wt% ZnO active agent.

[0073] To verify the necessity of each component and operation in the preparation method of the present invention, several comparative experiments were conducted.

[0074] Comparative Example 1

[0075] In this comparative example, the similarities between the preparation methods and those in Example 1 will not be repeated here; only the differences from the preparation methods in Example 1 will be described. The difference between Comparative Example 1 and Example 1 is that, in the second step, SDBS was not used; that is, Cu(NO3)2 was only prepared into a solution as the precursor liquid for the active component. The rest of the preparation was carried out as described in Example 1, and catalyst D1 was obtained.

[0076] Comparative Example 2

[0077] In this comparative example, the preparation methods are the same as those in Example 1, and will not be repeated here. Only the differences from the preparation methods in Example 1 will be described. The difference between Comparative Example 2 and Example 1 is that, in the last step, calcination was carried out without Ar atmosphere protection; otherwise, the catalyst D2 was prepared as described in Example 1.

[0078] Comparative Example 3

[0079] In this comparative example, the preparation method is the same as that in Example 1, and will not be repeated here. Only the differences from the preparation method in Example 1 will be described. The difference between Comparative Example 3 and Example 1 is that in the third step, an equal mass of Al2O3 was used instead of MgAlO4 as the support, and in the last step, calcination was carried out without Ar atmosphere protection; the rest is the same as described in Example 1, and catalyst D3 was prepared.

[0080] Comparative Example 4

[0081] In this comparative example, the preparation methods are the same as those in Example 1, and will not be repeated here. Only the differences from the preparation methods in Example 1 will be described. The difference between Comparative Example 1 and Example 1 is that in step 1, Zn(NO3)2 is 210.45 g, and in step 3, MgAlO4 is 60 g; the rest are as described in Example 1, and catalyst D4 was prepared.

[0082] Comparative Example 5

[0083] In this comparative example, the preparation methods are the same as those in Example 1, and will not be repeated here. Only the differences from the preparation methods in Example 1 will be described. The difference between Comparative Example 1 and Example 1 is that in step 1, Zn(NO3)2 is 145.45 g, and in step 3, MgAlO4 is 36 g; the rest are as described in Example 1, and catalyst D5 was obtained.

[0084] Comparative Example 6

[0085] In this comparative example, the preparation methods are the same as those in Example 1, and will not be repeated here. Only the differences from the preparation methods in Example 1 will be described. The difference between Comparative Example 1 and Example 1 is that, in the third step, the specific surface area of ​​MgAlO4 is 150 m². 2 / g~190m 2 / g; the rest were prepared according to Example 1, and catalyst D6 was obtained.

[0086] Comparative Example 7

[0087] In this comparative example, the preparation methods are the same as those in Example 1, and will not be repeated here. Only the differences from the preparation methods in Example 1 will be described. The difference between Comparative Example 1 and Example 1 is that, in the third step, the specific surface area of ​​MgAlO4 is 230 m². 2 / g~250m 2 / g; the rest were prepared according to the method described in Example 1, and catalyst D7 was obtained.

[0088] Comparative Example 8

[0089] In this comparative example, the preparation methods are the same as those in Example 1, and will not be repeated here. Only the differences from the preparation methods in Example 1 will be described. The difference between Comparative Example 1 and Example 1 is that in the third step, the water absorption rate of MgAlO4 is 40% to 50%; the rest is as described in Example 1, and catalyst D8 was prepared.

[0090] Comparative Example 9

[0091] In this comparative example, the preparation methods are the same as those in Example 1, and will not be repeated here. Only the differences from the preparation methods in Example 1 will be described. The difference between Comparative Example 1 and Example 1 is that in the third step, the pH of the system is about 6.5, which is slightly acidic; the rest is the same as described in Example 1, and catalyst D9 was prepared.

[0092] Comparative Example 10

[0093] In this comparative example, the preparation methods are the same as those in Example 1, and will not be repeated here. Only the differences from the preparation methods in Example 1 will be described. The difference between Comparative Example 1 and Example 1 is that in the third step, the pH of the system is about 8, which is alkaline; the rest is the same as described in Example 1, and catalyst D10 was prepared.

[0094] Catalyst performance evaluation

[0095] The catalysts prepared in Examples 1-6 and Comparative Examples 1-10 were loaded into a shift converter for performance evaluation. The main composition (volume fraction) of the feed gas was: CO: 65%, CO2: 4%, H2: 12%, N2: 15%, and other components: 4%. Reaction conditions were: pressure 2.0 MPa, space velocity 4000 h⁻¹. -1 The reaction inlet temperature is 180℃~400℃, and the vapor-to-gas ratio (molar ratio) is 0.6~0.8.

[0096] Meanwhile, the CO conversion rate of the catalysts prepared in each embodiment and comparative example was tested by running them continuously at 280°C for 500 hours.

[0097] The catalytic activity and thermal stability (i.e., the activity after continuous operation at 280℃ for 500h) evaluation data of each catalyst are shown in Table 1 below.

[0098] Table 1 Comparison of catalytic activity and thermal stability of the catalysts provided in the examples and comparative examples.

[0099]

[0100] As can be seen from the data in Table 1, the catalyst prepared by this method can exhibit an excellent CO conversion rate of over 90% at 200℃, 280℃ and 350℃, especially the catalyst in Example 1, which has the best catalytic thermal stability and conversion rate.

[0101] In contrast, the catalyst provided in Comparative Example 1, due to the lack of surfactant, resulted in uncontrollable Cu particle size and uneven particle size distribution during catalyst synthesis, leading to a significant decrease in activity (i.e., CO conversion rate) during use. The catalyst provided in Comparative Example 2, due to the absence of inert gas protection during calcination, experienced catalyst particle agglomeration, resulting in a significant decrease in CO conversion rate. The catalyst provided in Comparative Example 3, using Al2O3 as a support and without inert gas protection during calcination, exhibited a significantly reduced CO conversion rate, continuing the downward trend compared to Comparative Example 2. The catalysts provided in Comparative Examples 4 and 5, where the molar ratio of active component to active additive is outside the range of 1:0.8 to 1, exhibit significantly reduced CO conversion rates. This demonstrates that the relative amounts of active component and active additive during preparation significantly affect the performance of the final catalyst product. Even when adjusting the amount of support to ensure the relative proportions of each component in the catalyst product (calculated based on the total amount of copper and zinc loaded on the support) meet the aforementioned limitations of this invention, poor product performance still occurs. This may be due to the relatively small amount of support failing to adequately load Cu particles and / or active additives, thus preventing a balance in their relative content. The catalysts provided in Comparative Examples 6 and 7, where the MgAlO4 support has a specific surface area of ​​200 m², exhibit... 2 / g~220m 2 Outside the range of / g, the CO conversion rate decreased significantly. The catalyst provided in Comparative Example 8, with its low water absorption rate of the MgAlO4 support, insufficient loading of the active component and active auxiliary agent, and weak interaction strength, resulted in a significant decrease in CO conversion rate. The catalysts provided in Comparative Examples 9 and 10, where the reaction system pH was slightly acidic or more alkaline outside the range of 7–7.5 during preparation, exhibited a significant decrease in CO conversion rate.

[0102] Meanwhile, in the above comparative examples, in addition to the poor catalytic activity at different temperatures, the thermal stability of the activity test after continuous operation at 280℃ for 500h was also worse, showing a significant decrease.

[0103] The detailed process of thermal stability of the catalysts prepared in Example 1 and Comparative Example 1 was compared, such as... Figure 3 As shown. From Figure 3 As can be seen, the CO conversion rate of catalyst S1 provided in Example 1 remained basically unchanged, while the CO conversion rate of catalyst D1 provided in Comparative Example 1 began to show a significant downward trend after 300 hours of operation. This indicates that catalyst S1 provided in Example 1 exhibits better thermal stability and service life than catalyst D1 provided in Comparative Example 1. Therefore, the application of surfactants in the preparation process plays a crucial role in improving the thermal stability and service life of the obtained catalyst.

[0104] The above embodiments are for illustrative purposes only and do not constitute a specific limitation on the invention. For example, the composite oxide support is not limited to MgAlO4 in the above embodiments, but can also be other compounds with alkaline earth metal-AlO4 structures such as CaAlO4, BaAlO4, and SrAlO4, which have similar structures and functions. Similarly, the active agent is not limited to ZnO in the above embodiments, but can also be other active agents commonly used in Cu-based catalysts for CO conversion reactions, such as ZrO2 and K2O. Obviously, any modifications made without departing from the basic concept of the invention, as well as any obvious modifications derived therefrom, fall within the scope of protection of this invention.

Claims

1. A sub-nanometer-scale Cu-based intermediate-temperature shift catalyst, characterized in that, It consists of 20%–30% of a composite oxide support, 30%–40% of Cu sub-nano particles loaded on the composite oxide support, and 30%–40% of an active agent, all of which are mass percentages; wherein, at least 90% of the Cu sub-nano particles have a size of less than 2 nm; the composite oxide support is a compound with an alkaline earth metal-AlO4 structure; and the active agent is selected from any one of ZnO, ZrO2, and K2O.

2. The Cu-based intermediate-temperature shift catalyst according to claim 1, characterized in that, The composite oxide support is selected from any one of MgAlO4, CaAlO4, BaAlO4, and SrAlO4.

3. The Cu-based intermediate-temperature shift catalyst according to claim 2, characterized in that, The composite oxide support is MgAlO4.

4. The Cu-based intermediate-temperature shift catalyst according to claim 3, characterized in that, The specific surface area of ​​the composite oxide carrier is 180 m². 2 / g~250m 2 / g, water absorption rate is 60%~80%.

5. The Cu-based intermediate-temperature shift catalyst according to any one of claims 1 to 4, characterized in that, The composite oxide carrier has a constructed geometry.

6. A method for preparing a sub-nanometer-scale Cu-based intermediate-temperature shift catalyst, characterized in that, Including the following steps: S1. Disperse the water-soluble salt of the active adjuvant ion in an alcohol solution to obtain an active adjuvant precursor solution; the active adjuvant ion is selected from Zn. 2+ Zr 4+ K + Any one of them; S2. Mix the water-soluble salt of Cu with the surfactant to obtain the precursor solution of the active component; wherein, Cu 2+ The molar ratio of the surfactant to the surfactant is 1:1 to 3; S3. After thoroughly mixing the active component precursor liquid and the active auxiliary agent precursor liquid, add the composite oxide support, allow it to stand and age, and then dry to obtain the catalyst precursor; wherein, the specific surface area of ​​the composite oxide support is 200 m². 2 / g~220m 2 / g, water absorption rate 60%–80%; Cu in the precursor fluid of the active component 2+ The molar ratio of the active adjuvant ions in the precursor fluid to the active adjuvant is 1:0.8 to 1; S4. The catalyst precursor is calcined at 380℃~400℃ for 4h~6h under a protective gas atmosphere, and then reduced with H2 at 200℃~250℃ for 4h~6h to obtain the Cu-based medium-temperature shift catalyst.

7. The preparation method according to claim 6, characterized in that, In step S1, the mass concentration of the alcohol solution is 50 wt% to 70 wt%.

8. The preparation method according to claim 6, characterized in that, The surfactant is selected from at least one of hexadecyltrimethylammonium bromide, sodium dodecylbenzenesulfonate, and polyethylene glycol.

9. The preparation method according to claim 6, characterized in that, The water-soluble salt of Cu is selected from at least one of Cu(NO3)2, Cu(CH3CH2O)2, and CuSO4; the water-soluble salt of the active agent is selected from at least one of nitrate, chloride, acetate, and sulfate.

10. The application of a Cu-based intermediate-temperature shift catalyst as described in any one of claims 1 to 5 in a CO shift reaction, characterized in that, The Cu-based intermediate temperature shift catalyst is used in the temperature range of 180℃ to 400℃.

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