A supported heterogeneous catalyst of oxide synergistic with copper-manganese spinel and its application in the oxygen-free dehydrogenation of ethanol to acetaldehyde.

Abstract

This invention discloses the application of an oxide-coated copper-manganese spinel supported heterogeneous catalyst in the oxygen-free dehydrogenation of ethanol to acetaldehyde, belonging to the field of heterogeneous catalysis technology for the oxygen-free dehydrogenation of ethanol to acetaldehyde and hydrogen production. The reaction is carried out in a fixed-bed reactor under a nitrogen atmosphere at a temperature of 280°C and a mass hourly space velocity (WHSV) of 66.1 h⁻¹. ‑1 Under the given conditions, the ethanol conversion rate was 72.5%, the acetaldehyde selectivity was 95.0%, and the space-time yield of acetaldehyde based on copper-manganese composite oxides was 43.5 h⁻¹. ‑1 This invention achieves highly selective preparation of acetaldehyde and hydrogen under relatively mild conditions. The system possesses significant advantages, including simple catalyst preparation, high catalytic activity under high mass space velocity (MHSV) conditions, high MHSV yield of acetaldehyde, high atom utilization, and good stability. The CuMnTi-1 catalyst of this invention remains stable for over 70 hours. CuMnTi-1 improves the utilization rate of copper and manganese, enhances catalytic performance, reduces the amount of copper-manganese spinel required in the reaction, and lowers the overall cost of catalyst preparation.

Description

Technical Field

[0001] This invention relates to the preparation of spinel catalytic materials and their application in the field of heterogeneous catalysis for oxygen-free dehydrogenation, specifically to the preparation of acetaldehyde and hydrogen through an oxygen-free dehydrogenation process using ethanol as a reactant and a supported copper-manganese composite oxide as a heterogeneous catalyst. Background Technology

[0002] Actively developing and researching alternative energy sources has become an important task. In recent years, biomass ethanol has demonstrated significant advantages, including large annual production, wide distribution, renewability, and environmental friendliness, making its high-value utilization particularly necessary. Currently, ethanol can be converted into high-value-added products such as butanol and 1,3-butadiene. Ethanol dehydrogenation, as a key step in this process, has been studied extensively, opening up effective pathways for converting ethanol into high-value-added products. Furthermore, acetaldehyde, as a crucial organic synthesis intermediate, can be further converted into various chemical products such as acetic acid, ethyl acetate, peracetic acid, and pentaerythritol, possessing extremely high application value.

[0003] Currently, the main methods for preparing acetaldehyde include ethylene oxidation, acetylene hydration, and ethanol oxidation. The first two methods have some industrial applications, but they have significant limitations: their raw materials are highly dependent on fossil fuels, the production process is harmful to equipment and the environment, and the catalyst costs are high. In comparison, ethanol oxidation is more advantageous. This method can be further divided into two routes: ethanol oxidative dehydrogenation and ethanol oxygen-free dehydrogenation. However, in the research of ethanol oxygen-free dehydrogenation, most catalysts still face technical bottlenecks such as poor stability and low throughput. For example, Chinese patent application CN 106673977 A uses a Cu-supported silica catalyst at 220℃, atmospheric pressure, and a mass hourly space velocity of 2.37 h⁻¹. -1 Under these conditions, the ethanol conversion rate was 53.4%, and the acetaldehyde selectivity was 92.1%. Chinese patent application CN 110479337 A loaded the active component Co2C onto reduced graphene oxide material, achieving the desired results at 400℃, atmospheric pressure, and a mass hourly space velocity of 0.032 h⁻¹. -1 Under these conditions, the ethanol conversion rate was 88.1%, and the acetaldehyde selectivity was 99.1%. Chinese patent application CN 105148911 A describes loading Cu onto carbon material and achieving the desired results at 260°C and a mass hourly space velocity (HHSV) of 2.37 h⁻¹. -1 Under normal pressure, the ethanol conversion rate is 62.3%, and the acetaldehyde selectivity is 93.4%.

[0004] Copper-manganese spinel has recently demonstrated excellent catalytic performance in the anaerobic dehydrogenation of ethanol to acetaldehyde and in hydrogen production. Our research group has conducted related investigations and has applied for a Chinese invention patent (CN 118976511 A). The optimal catalytic performance of copper-manganese spinel at 280℃, atmospheric pressure, and a mass hourly space velocity (HHSV) of 28.83 h⁻¹ is also observed. -1Under these conditions, the ethanol conversion rate can reach 84.3%, and the acetaldehyde selectivity is 95%. Based on the copper-manganese spinel catalyst-based heterogeneous catalytic system for the oxy-free dehydrogenation of ethanol to acetaldehyde and hydrogen previously developed by our research group, this invention aims to develop a more efficient copper-manganese heterogeneous catalytic system for the oxy-free dehydrogenation of ethanol to acetaldehyde. Summary of the Invention

[0005] The present invention aims to provide an application of a supported heterogeneous catalyst of oxide synergistic with copper-manganese spinel in the oxygen-free dehydrogenation of ethanol to acetaldehyde. The supported copper-manganese composite oxide catalyst, CuMnO, is prepared by a sol-gel method assisted by ammonia water pH adjustment combined with mechanical mixing. x Copper oxide (CuO), manganese trioxide (Mn₂O₃), copper-manganese spinel (CuMn₂O₄), and supported titanium oxide (TiO₂) play a synergistic role in the reaction system. This acetaldehyde preparation method features a simple reaction process, high catalyst selectivity for acetaldehyde, large ethanol throughput, and simple preparation, showing promising industrial application potential. Under normal pressure, the supported copper-manganese composite oxide catalyst can achieve an ethanol flow rate of 4.02 mL / h. -1 The mass hourly space velocity is 66.1 h. -1 The ethanol conversion rate can reach 72.5%, the acetaldehyde selectivity is 95.0%, and the space-time yield of acetaldehyde from the active catalyst component, copper-manganese composite oxide, is 43.5 h⁻¹. -1 The copper-manganese spinel catalyst has a mass hourly space velocity (WHSV) of 66.1 h⁻¹ in this system. -1 This catalyst exhibits a higher mass hourly space velocity (MHSV) than previously reported values, addressing the issue of low catalyst mass hourly space velocity in the ethanol dehydrogenation to acetaldehyde reaction system. It achieves high catalytic activity under high MHSV conditions, while also realizing high product space-time yield and high atom utilization, indicating broad prospects for industrial application. The CuMnTi-1 catalyst of this invention remains stable for over 70 hours without significant deactivation. This CuMnTi-1 catalyst improves the utilization rate of copper and manganese, enhances catalytic performance, reduces the amount of copper-manganese spinel required in the reaction, and lowers the overall cost of catalyst preparation.

[0006] The copper-manganese composite oxide catalyst prepared by the sol-gel method assisted by ammonia water pH adjustment and mechanical mixing in this invention was tested at 280℃ and atmospheric pressure with an ethanol flow rate of 4.02 mL / h. -1 The mass hourly space velocity is 66.1 h. -1 The ethanol conversion rate reached 72.5%, the acetaldehyde selectivity was 95.0%, and the space-time yield of acetaldehyde based on copper-manganese composite oxide in the catalyst was 43.5 h⁻¹. -1 .

[0007] Note: The mass hourly space velocity mentioned in this invention is the ratio of the mass flow rate of ethanol passing through the reactor per unit time to the mass of copper-manganese composite oxide.

[0008] Copper-manganese composite oxide CuMnO x It is composed of copper-manganese spinel CuMn2O4 and CuO, Mn2O3.

[0009] To solve the technical problem of this invention, the proposed technical solution is as follows: An application of a supported copper-manganese composite oxide catalyst in the dehydrogenation of ethanol to acetaldehyde. The preparation method of the supported copper-manganese composite oxide catalyst is as follows: Cu(NO3)2·3H2O, Mn(CH3COO)2·4H2O, and citric acid are dissolved in deionized water and stirred until homogeneous. Ammonia water is added dropwise to adjust the pH to 6-7. The resulting wet gel is obtained by continuously stirring the mixed solution and then dried in an oven to obtain a dry gel. The dry gel is then calcined in an air muffle furnace to obtain a copper-manganese composite oxide, wherein the copper-manganese metal molar ratio is 1:2. Finally, the copper-manganese composite oxide and anatase titanium dioxide are mechanically stirred and calcined in an air muffle furnace to obtain a CuMnTi-1 catalyst, wherein the mass fraction of the copper-manganese composite oxide is 40%.

[0010] Preferably, the supported copper-manganese composite oxide catalyst CuMnTi-1 is mixed evenly with quartz sand and placed in the reaction tube of a fixed-bed reactor. A micro-injection pump is used to deliver 4.02 mL·h. -1 Anhydrous ethanol was pumped into a preheater at a flow rate of [missing information], vaporized, mixed with carrier gas N2, and then entered the reaction bed. The reaction was carried out at 280°C, atmospheric pressure, and a mass hourly space velocity (HHSV) of 66.1 h⁻¹. -1 Under certain conditions, acetaldehyde and hydrogen are produced by the reaction.

[0011] Preferably, 2.03 g Cu(NO3)2·3H2O, 4.12 g Mn(CH3COO)2·4H2O, and 4.84 g citric acid are dissolved in 25 mL of deionized water to form a mixed solution. Ammonia is added dropwise to adjust the pH to 6-7. The mixed solution is then continuously stirred at 80 °C to obtain a wet gel, which is then placed in a 120 °C oven for 24 h to obtain a dry gel. The dry gel is then calcined in an air muffle furnace at 800 °C for 4 h and cooled to room temperature to obtain copper-manganese composite oxide (CuMnO). x Finally, CuMnO x After mechanical stirring with TiO2, the mixture was calcined in an air muffle furnace at 700℃ for 4 hours to obtain the CuMnTi-1 catalyst.

[0012] 120 mg of CuMnTi-1 catalyst was mixed with 400 mg of quartz sand and loaded into the reaction tube of a fixed-bed reactor. A micro-injection pump was used to dispense 4.02 mL / h. -1 Anhydrous ethanol is pumped into a preheater at a flow rate of [missing information] to vaporize, mixes with carrier gas N2, and then enters the reaction bed. The reaction proceeds at 280°C, atmospheric pressure, and a mass hourly space velocity (HHSV) of 66.1 h⁻¹. -1 The reaction takes place under the specified conditions.

[0013] Preferably, Cu(NO3)2·3H2O, Mn(CH3COO)2·4H2O, and citric acid are dissolved in deionized water and stirred until homogeneous. Ammonia water is added dropwise to adjust the pH to 6-7. The mixture is continuously stirred to obtain a wet gel. The wet gel is placed in an oven for drying. The resulting solid is placed in a muffle furnace and calcined in air to obtain a copper-manganese composite oxide, wherein the copper-manganese molar ratio is 1:2. The prepared copper-manganese composite oxide and anatase titanium dioxide are placed together in a ball mill jar, 15 mL of deionized water is added, and the mixture is ball-milled for 24 h. The resulting liquid mixture is placed in an oven for drying. The resulting solid is placed in a muffle furnace and calcined in air to obtain a CuMnTi-2 catalyst.

[0014] Preferably, Cu(NO3)2·3H2O and Mn(CH3COO)2·4H2O are ground and mixed evenly, and the resulting mixture is placed in a muffle furnace and calcined in air to obtain a copper-manganese composite oxide. The prepared copper-manganese composite oxide and anatase titanium dioxide are placed together in a ball mill jar, and 15 mL of deionized water is added for ball milling for 24 h. The resulting liquid material is placed in an oven for drying, and the resulting solid material is placed in a muffle furnace and calcined in air to obtain a CuMnTi-3 catalyst.

[0015] Preferably, Cu(NO3)2·3H2O and Mn(CH3COO)2·4H2O are dissolved in deionized water and denoted as solution A; NaOH and Na2CO3 are dissolved in deionized water and denoted as solution B; TiO2 is dissolved in deionized water and denoted as solution C. Solution A is placed in an oil bath at 65°C, and solution C is added dropwise to solution A. The mixture is stirred for 30 min and denoted as solution D. Solution B is added dropwise to solution D and the mixture is stirred for 12 h. The mixture is then allowed to cool naturally to room temperature, removed, and filtered until the solution is neutral. The solid material is dried at 100°C for 12 h, ground, and then placed in a muffle furnace for calcination in air to obtain the CuMnTi-4 catalyst.

[0016] Beneficial effects:

[0017] The copper-manganese composite oxide catalyst prepared by the sol-gel method assisted by ammonia water pH adjustment and mechanical mixing in this invention was tested at 280℃ and atmospheric pressure with an ethanol flow rate of 4.02 mL / h. -1 The mass hourly space velocity is 66.1 h. -1 The ethanol conversion rate can reach 72.5%, the acetaldehyde selectivity is 95.0%, and the space-time yield of the active component acetaldehyde in the catalyst is 43.5 h⁻¹. -1Based on the previously developed copper-manganese spinel catalyst system for the oxygen-free dehydrogenation of ethanol to acetaldehyde and hydrogen, this research aims to develop a more efficient copper-manganese heterogeneous catalyst for the oxygen-free dehydrogenation of ethanol to acetaldehyde. The CuMnTi-1 catalyst of this invention achieves a mass hourly space velocity (HHSV) of 66.1 h⁻¹. -1 At 280℃, the space-time yield of the target product acetaldehyde was increased to twice that of the copper-manganese spinel catalyst in Chinese invention patent CN 118976511 A. The CuMnTi-1 catalyst of this invention can remain stable for more than 70 hours without significant deactivation (i.e., Example 1), which is more than 30 hours longer than the stability time of the copper-manganese spinel catalyst in Chinese invention patent CN 118976511 A.

[0018] (1) The supported copper-manganese composite oxide catalyst has a mass space velocity of 66.1 h⁻¹ in this system. -1 The ethanol conversion rate can reach 72.5%, the acetaldehyde selectivity is 95.0%, and the space-time yield of the active component acetaldehyde in the catalyst is 43.5 h⁻¹. -1 Significant breakthroughs have been made in the fields of ethanol dehydrogenation to acetaldehyde and hydrogen production, with broad prospects for industrial applications.

[0019] (2) Under the same experimental conditions, the ethanol conversion rate significantly increased with increasing reaction temperature, from 35.5% at 230℃ to 78.9% at 300℃. The selectivity of the target product acetaldehyde was approximately 95.0%. Later, we determined to use 280℃ for long-term stability testing. Figure 1 We can see that the CuMnTi-1 catalyst operates at a mass space velocity of 66.1 h⁻¹. -1 At 280°C, the catalyst remained stable for more than 70 hours without significant deactivation (i.e., Example 1).

[0020] (3) Adjusting the ethanol flow rate to regulate the ethanol mass hourly space velocity (MHSV) has a certain impact on both the ethanol conversion rate and selectivity. The MHSV was adjusted from 50.3 h⁻¹ to 50.3 h⁻¹. -1 (i.e., Example 7) Increased to 90.8h -1 (i.e., Example 9) The ethanol conversion rate decreased from 74.2% to 43.0%, the acetaldehyde selectivity remained at around 95.0%, and the mass hourly space velocity was 66.1 h⁻¹. -1 Under the given conditions, the ethanol conversion rate was 72.5%, and the acetaldehyde selectivity was approximately 95.0%. Later, we used a mass hourly space velocity (MHSV) of 66.1 h⁻¹. -1 The conditions for conducting the study (i.e., Example 1) were met.

[0021] (4) The effects of different catalyst preparation methods on the reaction system were explored. Co-precipitation, ammonia-based pH-adjusted sol-gel method combined with ball milling, ball milling, and ammonia-based pH-adjusted sol-gel method combined with mechanical mixing were investigated. Figure 3 It can be seen that the spinel crystal structure of the catalysts prepared by co-precipitation and ball milling is not as good as that of the catalyst prepared by the ammonia-adjusted pH sol-gel method combined with mechanical mixing. Furthermore, the ethanol conversion rates of both the ammonia-adjusted pH sol-gel method combined with ball milling and ball milling are lower than those of the ammonia-adjusted pH sol-gel method combined with mechanical mixing. The selectivity of the catalyst prepared by co-precipitation is also lower than that of the ammonia-adjusted pH sol-gel method combined with mechanical mixing. Therefore, we ultimately adopted the ammonia-adjusted pH sol-gel method combined with mechanical mixing (Example 1).

[0022] Preparation of catalysts.

[0023] (5) To explore the effect of different loadings of copper-manganese composite oxides on the reaction system, the loadings of copper-manganese composite oxides at mass percentages of 10% (CuMnTi-5), 20% (CuMnTi-6), and 40% (CuMnTi-1) were investigated. Compared with the catalyst with a mass percentage of 40%, the catalytic performance of the other two mass percentages was lower than that of the catalyst with a mass percentage of 40%, which was speculated to be related to the mass of the active component. Therefore, we finally used ammonia water to adjust the pH sol-gel method and mechanical mixing to prepare a catalyst with a mass percentage of 40% (i.e., Example 1).

[0024] (6) To explore the effect of different metal oxide supports on the reaction system, we explored TiO2, SiO2, Al2O3 and CeO2 as supports, and the catalytic performance of all of them was better than that of copper manganese spinel (CuMn2O4, Table 7). Finally, we used TiO2 as a support and prepared a supported copper manganese composite oxide catalyst by adjusting the pH with ammonia water, sol-gel method and mechanical mixing (i.e., Example 1).

[0025] (7) The effect of different copper:manganese molar ratios on the reaction system was explored, specifically the case where the copper:manganese molar ratio was 1:2.

[0026] Compared with the catalyst with a copper-manganese molar ratio of 1:2, the catalytic performance of the other two metal molar ratios (CuMnTi-1), 1:1 (CuMnTi-7), and 2:1 (CuMnTi-8) was slightly lower, which was presumably related to the number of metal active sites. Therefore, we finally used the sol-gel method with ammonia water to adjust the pH and combined it with mechanical mixing to prepare the supported copper-manganese composite oxide catalyst (i.e., Example 1).

[0027] (8) The effects of each component of the catalyst on the reaction system were explored, specifically CuO / TiO2, Mn2O3 / TiO2, CuO+Mn2O3 / TiO2, CuMn2O4, and CuMnO. x And TiO2. Compared with the CuMnTi-1 catalyst, the reaction activity of CuO alone or Mn2O3 supported on TiO2 is very low, with ethanol conversion rates of 72.5%, 10.2%, and 1.5%, respectively. The mechanically mixed CuO and Mn2O3 supported on TiO2 catalyst (CuO+Mn2O3 / TiO2) has an ethanol conversion rate of 38.3%, which is better than the catalytic performance of CuO alone or Mn2O3 supported on TiO2, but its performance is still lower than that of CuMnTi-1 catalyst. Taking CuMn2O4 spinel and TiO2 at a mass ratio of 40% of CuMnTi-1 catalyst, the results show that the ethanol conversion rate is 1.5% when TiO2 is the catalyst and 35.8% when CuMn2O4 spinel is the catalyst. Therefore, the active component of CuMnTi-1 catalyst is CuMnO x Furthermore, the copper-manganese composite oxide CuMnO x Copper oxide (CuO), manganese trioxide (Mn₂O₃), copper-manganese spinel (CuMn₂O₄), and the support TiO₂ play a synergistic role in the reaction system. Compared with the copper-manganese spinel catalyst in Chinese invention patent CN 118976511A, under the same reaction conditions, the CuMnTi-1 of this invention improves the utilization rate of copper and manganese, enhances catalytic performance, reduces the amount of copper-manganese spinel required in the reaction, and lowers the overall cost of catalyst preparation. Attached Figure Description

[0028] Figure 1 Stability diagram of CuMnTi-1 catalyst

[0029] Figure 2 This is a graph showing the catalytic performance of different metal oxide catalysts.

[0030] Figure 3 These are XRD patterns of supported copper-manganese composite oxide catalysts prepared by different methods. Detailed Implementation

[0031] The present invention is further described below through specific embodiments, but the following embodiments do not constitute a limitation on the scope of protection of the present invention.

[0032] Example 1

[0033] 2.03 g Cu(NO3)2·3H2O, 4.12 g Mn(CH3COO)2·4H2O, and 4.84 g citric acid were dissolved in 25 mL of deionized water to form a mixed solution. Ammonia was added dropwise to adjust the pH to 6–7. The mixed solution was then continuously stirred at 80 °C to obtain a wet gel, which was then placed in a 120 °C oven for 24 h to obtain a dry gel. The dry gel was then calcined in an air muffle furnace at 800 °C for 4 h and cooled to room temperature to obtain copper-manganese composite oxide (CuMnO). x Finally, 600mg CuMnO x After mechanical stirring with 900 mg TiO2, the mixture was calcined in an air muffle furnace at 700 °C for 4 h to obtain the CuMnTi-1 catalyst.

[0034] 120 mg of CuMnTi-1 catalyst was mixed with 400 mg of quartz sand (30-40 mesh) and then loaded into the reaction tube of a fixed-bed reactor. A micro-injection pump was used to deliver 4.02 mL / h. -1 Anhydrous ethanol is pumped into a preheater at a flow rate of [missing information] to vaporize, mixes with carrier gas N2, and then enters the reaction bed. The reaction proceeds at 280°C, atmospheric pressure, and a mass hourly space velocity (HHSV) of 66.1 h⁻¹. -1 Under the given conditions, the ethanol conversion rate was 72.5%, and the acetaldehyde selectivity was 95.0%. The reaction results are shown in Table 1. Unless otherwise specified, the flow rate of anhydrous ethanol in the examples was 4.02 mL·h. -1 After the reaction stabilized, the reactants and products were analyzed by online chromatography (DB-WAX column, FID detector; PorapakQ column + Colonne Micropacked Shincarbon ST column, TCD detector).

[0035] Example 2

[0036] 120 mg of CuMnTi-1 catalyst was mixed with 400 mg of quartz sand (30-40 mesh) and then loaded into the reaction tube of a fixed-bed reactor. A micro-injection pump was used to deliver 4.02 mL / h. -1 Anhydrous ethanol is pumped into a preheater at a flow rate of [missing information] to vaporize, mixes with carrier gas N2, and then enters the reaction bed. The reaction proceeds at 230°C, atmospheric pressure, and a mass hourly space velocity (HHSV) of 66.1 h⁻¹. -1 The reaction was carried out under the specified conditions, and the results are shown in Table 1. Example 3

[0037] 120 mg of CuMnTi-1 catalyst was mixed with 400 mg of quartz sand (30-40 mesh) and then loaded into the reaction tube of a fixed-bed reactor. A micro-injection pump was used to deliver 4.02 mL / h. -1 Anhydrous ethanol is pumped into a preheater at a flow rate of [missing information] to vaporize, mixes with carrier gas N2, and then enters the reaction bed. The reaction proceeds at 250°C, atmospheric pressure, and a mass hourly space velocity (HHSV) of 66.1 h⁻¹. -1The reaction was carried out under the specified conditions, and the results are shown in Table 1.

[0038] Example 4

[0039] 120 mg of CuMnTi-1 catalyst was mixed with 400 mg of quartz sand (30-40 mesh) and then loaded into the reaction tube of a fixed-bed reactor. A micro-injection pump was used to deliver 4.02 mL / h. -1 Anhydrous ethanol is pumped into a preheater at a flow rate of [missing information] to be preheated and vaporized. After mixing with carrier gas N2, it enters the reaction bed and is reacted at 250°C, atmospheric pressure, and a mass hourly space velocity of 66.1 h⁻¹. -1 The reaction was carried out under the specified conditions, and the results are shown in Table 1.

[0040] Example 5

[0041] 120 mg of CuMnTi-1 catalyst was mixed with 400 mg of quartz sand (30-40 mesh) and then loaded into the reaction tube of a fixed-bed reactor. A micro-injection pump was used to deliver 4.02 mL / h. -1 Anhydrous ethanol is pumped into a preheater at a flow rate of [missing information] to be preheated and vaporized. After mixing with carrier gas N2, it enters the reaction bed and is reacted at 290°C, atmospheric pressure, and a mass hourly space velocity of 66.1 h⁻¹. -1 The reaction was carried out under the specified conditions, and the results are shown in Table 1.

[0042] Example 6

[0043] 120 mg of CuMnTi-1 catalyst was mixed with 400 mg of quartz sand (30-40 mesh) and then loaded into the reaction tube of a fixed-bed reactor. A micro-injection pump was used to deliver 4.02 mL / h. -1 Anhydrous ethanol is pumped into a preheater at a flow rate of [missing information] to be preheated and vaporized. After mixing with carrier gas N2, it enters the reaction bed and is reacted at 300°C, atmospheric pressure, and a mass hourly space velocity of 66.1 h⁻¹. -1 The reaction was carried out under the specified conditions, and the results are shown in Table 1.

[0044] Table 1. Ethanol dehydrogenation performance of CuMnTi-1 catalyst at different temperatures.

[0045]

[0046] Summary: Examples 1-6 show that, under the same experimental conditions, the ethanol conversion rate significantly increases with increasing reaction temperature, from 35.5% at 230℃ to 78.9% at 300℃. The selectivity of the target product, acetaldehyde, remains around 95.0%. We later determined to use 280℃ for long-term stability testing. Figure 1 We can see that the CuMnTi-1 catalyst operates at a mass space velocity of 66.1 h⁻¹. -1At 280°C, the catalyst remained stable for more than 70 hours without significant deactivation (i.e., Example 1).

[0047] Example 7

[0048] 120 mg of CuMnTi-1 catalyst was mixed with 400 mg of quartz sand (30-40 mesh) and loaded into the reaction tube of a fixed-bed reactor. A micro-injection pump was used to deliver 3.06 mL / h of the mixture. -1 Anhydrous ethanol is pumped into a preheater at a flow rate of [missing information] to be preheated and vaporized. After mixing with carrier gas N2, it enters the reaction bed and is reacted at 280°C, atmospheric pressure, and a mass hourly space velocity of 50.3 h⁻¹. -1 The reaction was carried out under the specified conditions, and the results are shown in Table 2.

[0049] Example 8

[0050] 120 mg of CuMnTi-1 catalyst was mixed with 400 mg of quartz sand (30-40 mesh) and then loaded into the reaction tube of a fixed-bed reactor. A micro-injection pump was used to deliver 5.04 mL / h of the mixture. -1 Anhydrous ethanol is pumped into a preheater at a flow rate of 1000 m / s to be preheated and vaporized. After mixing with carrier gas N2, it enters the reaction bed and is reacted at 280 °C, atmospheric pressure, and a mass hourly space velocity of 82.9 h⁻¹. -1 The reaction was carried out under the specified conditions, and the results are shown in Table 2.

[0051] Example 9

[0052] 120 mg of CuMnTi-1 catalyst was mixed with 400 mg of quartz sand (30-40 mesh) and then loaded into the reaction tube of a fixed-bed reactor. A micro-injection pump was used to deliver 5.52 mL / h. -1 Anhydrous ethanol is pumped into a preheater at a flow rate of 90.8 h⁻¹ for preheating and vaporization. After mixing with carrier gas N₂, it enters the reaction bed and is reacted at 280°C, atmospheric pressure, and a mass hourly space velocity of 90.8 h⁻¹. -1 The reaction was carried out under the specified conditions, and the results are shown in Table 2.

[0053] Table 2. Ethanol dehydrogenation performance of CuMnTi-1 catalyst at different mass space velocities

[0054]

[0055] In summary, adjusting the ethanol flow rate to control the ethanol mass hourly space velocity (MHSV) has a certain impact on both the ethanol conversion rate and selectivity. The MHSV was adjusted from 50.3 h⁻¹ to 100 h⁻¹. -1 (i.e., Example 7) Increased to 90.8h -1 (i.e., Example 9) The ethanol conversion rate changed from 74.2% to 43.0%, the acetaldehyde selectivity changed from 96.1% to 95.8%, and the mass hourly space velocity was 66.1 h⁻¹. -1Under the given conditions, the ethanol conversion rate was 72.5%, and the acetaldehyde selectivity was approximately 95.0%. Later, we used a mass hourly space velocity (MHSV) of 66.1 h⁻¹. -1 The conditions for conducting the study (i.e., Example 1) were met.

[0056] Example 10

[0057] The catalyst was prepared as follows: 2.03 g of Cu(NO3)2·3H2O, 4.12 g of Mn(CH3COO)2·4H2O, and 4.84 g of citric acid were dissolved in 25 mL of deionized water to form a mixed solution. Ammonia was added dropwise to adjust the pH to 6-7. The mixed solution was then continuously stirred at 80 °C to obtain a wet gel, which was then placed in a 120 °C oven for 24 h to obtain a dry gel. The dry gel was then calcined in an air muffle furnace at 800 °C for 4 h and cooled to room temperature to obtain a copper-manganese composite oxide (CuMnO). x The copper-manganese molar ratio is 1:2; finally, 1000 mg CuMnO x The mixture was placed together with 1500 mg of anatase TiO2 in a ball mill jar, and then 15 mL of deionized water was added and the mixture was ball milled for 24 h. The resulting mixture was dried in an oven at 80 °C for 12 h, and then calcined in a muffle furnace at 700 °C for 4 h in an air atmosphere. After cooling to room temperature, it was taken out, ground, and used as a CuMnTi-2 catalyst.

[0058] 120 mg of CuMnTi-2 catalyst was mixed with 400 mg of quartz sand (30-40 mesh) and then loaded into the reaction tube of a fixed-bed reactor. A micro-injection pump was used to deliver 4.02 mL / h. -1 Anhydrous ethanol is pumped into a preheater at a flow rate of [missing information] to be preheated and vaporized. After mixing with carrier gas N2, it enters the reaction bed and is reacted at 280°C, atmospheric pressure, and a mass hourly space velocity of 66.1 h⁻¹. -1 The reaction was carried out under the specified conditions, and the results are shown in Table 3.

[0059] Example 11

[0060] Specific preparation method of the catalyst: 2.03g Cu(NO3)2·3H2O and 4.12g Mn(CH3COO)2·4H2O were ground and mixed evenly. The resulting mixture was then placed in a muffle furnace and calcined in air to obtain copper-manganese composite oxide. Then, 1000mg CuMnO was added... x The mixture was placed together with 1500 mg of anatase TiO2 in a ball mill jar, and then 15 mL of deionized water was added and the mixture was ball milled for 24 h. The resulting mixture was dried in an oven at 80 °C for 12 h, and then calcined in a muffle furnace at 700 °C for 4 h in an air atmosphere. After cooling to room temperature, it was taken out, ground, and used as a CuMnTi-3 catalyst.

[0061] 120 mg of CuMnTi-3 catalyst was mixed with 400 mg of quartz sand (30-40 mesh) and then loaded into the reaction tube of a fixed-bed reactor. A micro-injection pump was used to deliver 4.02 mL / h. -1 Anhydrous ethanol is pumped into a preheater at a flow rate of [missing information] to be preheated and vaporized. After mixing with carrier gas N2, it enters the reaction bed and is reacted at 280°C, atmospheric pressure, and a mass hourly space velocity of 66.1 h⁻¹. -1 The reaction was carried out under the specified conditions, and the results are shown in Table 3.

[0062] Example 12

[0063] The specific preparation method of the catalyst is as follows: 0.87g Cu(NO3)2·3H2O and 1.76g Mn(CH3COO)2·4H2O are dissolved in deionized water and labeled as solution A. 0.99g NaOH and 2.63g Na2CO3 are dissolved in deionized water and labeled as solution B. 1.20g TiO2 is dissolved in deionized water and labeled as solution C. Solution A is placed in an oil bath at 65℃. Solution C is added dropwise to solution A and stirred for 30min and labeled as solution D. Then, solution B is added dropwise to solution D and stirred for 12h. The solution is allowed to cool naturally to room temperature, removed, and filtered until it is neutral. The solid material is dried at 100℃ for 12h. The dried material is then calcined in a muffle furnace at 500℃ for 4h in an air atmosphere to obtain the CuMnTi-4 catalyst.

[0064] 120 mg of CuMnTi-1 and CuMnTi-4 catalysts were mixed with 400 mg of quartz sand (30-40 mesh) and loaded into the reaction tube of a fixed-bed reactor. A micro-injection pump was used to deliver 4.02 mL / h of the mixture. -1 Anhydrous ethanol is pumped into a preheater at a flow rate of [missing information] to be preheated and vaporized. After mixing with carrier gas N2, it enters the reaction bed and is reacted at 280°C, atmospheric pressure, and a mass hourly space velocity of 66.1 h⁻¹. -1 The reaction was carried out under the specified conditions, and the results are shown in Table 3.

[0065] Table 3. Ethanol dehydrogenation performance of catalysts prepared by different methods

[0066]

[0067] Summary: This study explored the effects of different catalyst preparation methods on the reaction system, specifically investigating the effects of ammonia-adjusted pH sol-gel method combined with mechanical mixing, ammonia-adjusted pH sol-gel method combined with ball milling, ball milling, and co-precipitation. Figure 3It can be seen that the spinel crystal structure of the catalysts prepared by co-precipitation and ball milling is not as good as that of the catalysts prepared by the ammonia-adjusted pH sol-gel method combined with mechanical mixing. In addition, the ethanol conversion rate of the catalysts prepared by the ammonia-adjusted pH sol-gel method combined with ball milling and ball milling is lower than that of the ammonia-adjusted pH sol-gel method combined with mechanical mixing. The selectivity of the catalysts prepared by co-precipitation is also lower than that of the ammonia-adjusted pH sol-gel method combined with mechanical mixing. Therefore, we finally adopted the ammonia-adjusted pH sol-gel method combined with mechanical mixing (Example 1) to prepare the catalyst.

[0068] Note: SG+MM—pH adjustment with ammonia, sol-gel method combined with mechanical mixing; CM—co-precipitation method;

[0069] SG+BG—Ammonia water for pH adjustment, sol-gel method combined with ball milling; BG—Ball milling method.

[0070] Example 13

[0071] 2.03 g Cu(NO3)2·3H2O, 4.12 g Mn(CH3COO)2·4H2O, and 4.84 g citric acid were dissolved in 25 mL of deionized water to form a mixed solution. Ammonia was added dropwise to adjust the pH to 6–7. The mixed solution was then continuously stirred at 80 °C to obtain a wet gel, which was then placed in a 120 °C oven for 24 h to obtain a dry gel. The dry gel was then calcined in an air muffle furnace at 800 °C for 4 h and cooled to room temperature to obtain copper-manganese composite oxide (CuMnO). x Finally, 200mg CuMnO x After mechanical stirring with 1800 mg TiO2, the mixture was calcined in an air muffle furnace at 700 °C for 4 h to obtain the CuMnTi-5 catalyst.

[0072] 120 mg of CuMnTi-5 catalyst was mixed with 400 mg of quartz sand (30-40 mesh) and then loaded into the reaction tube of a fixed-bed reactor. A micro-injection pump was used to deliver 4.02 mL / h. -1 Anhydrous ethanol is pumped into a preheater at a flow rate of [missing information] to be preheated and vaporized. After mixing with carrier gas N2, it enters the reaction bed and is reacted at 280°C, atmospheric pressure, and a mass hourly space velocity of 66.1 h⁻¹. -1 The reaction was carried out under the specified conditions, and the results are shown in Table 1.

[0073] Example 14

[0074] 2.03 g Cu(NO3)2·3H2O, 4.12 g Mn(CH3COO)2·4H2O, and 4.84 g citric acid were dissolved in 25 mL of deionized water to form a mixed solution. Ammonia was added dropwise to adjust the pH to 6–7. The mixed solution was then continuously stirred at 80 °C to obtain a wet gel, which was then placed in a 120 °C oven for 24 h to obtain a dry gel. The dry gel was then calcined in an air muffle furnace at 800 °C for 4 h and cooled to room temperature to obtain copper-manganese composite oxide (CuMnO). x Finally, 300mg CuMnO x After mechanical stirring with 1200 mg TiO2, the mixture was calcined in an air muffle furnace at 700 °C for 4 h to obtain the CuMnTi-6 catalyst.

[0075] 120 mg of CuMnTi-1 and CuMnTi-6 catalysts were mixed with 400 mg of quartz sand (30-40 mesh) and loaded into the reaction tube of a fixed-bed reactor. A micro-injection pump was used to deliver 4.02 mL / h of the mixture. -1 Anhydrous ethanol is pumped into a preheater at a flow rate of [missing information] to be preheated and vaporized. After mixing with carrier gas N2, it enters the reaction bed and is reacted at 280°C, atmospheric pressure, and a mass hourly space velocity of 66.1 h⁻¹. -1 The reaction was carried out under the specified conditions, and the results are shown in Table 4.

[0076] Table 4. Ethanol dehydrogenation performance of catalysts with different copper-manganese composite oxide mass ratios

[0077]

[0078] Summary: This study explored the effect of different mass ratios of copper-manganese composite oxides to the support on the reaction system. The mass percentages of copper-manganese composite oxides were investigated at 10% (CuMnTi-5), 20% (CuMnTi-6), and 40% (CuMnTi-1). Compared to the catalyst with a mass ratio of 40%, the catalytic performance of the other two mass ratios was lower, which is presumably related to the mass of the active component. Therefore, we finally prepared a catalyst with a mass ratio of 40% using a sol-gel method with pH adjustment using ammonia combined with mechanical mixing (i.e., Example 1).

[0079] Example 15

[0080] 2.03 g Cu(NO3)2·3H2O, 4.12 g Mn(CH3COO)2·4H2O, and 4.84 g citric acid were dissolved in 25 mL of deionized water to form a mixed solution. Ammonia was added dropwise to adjust the pH to 6–7. The mixed solution was then continuously stirred at 80 °C to obtain a wet gel, which was then placed in a 120 °C oven for 24 h to obtain a dry gel. The dry gel was then calcined in an air muffle furnace at 800 °C for 4 h and cooled to room temperature to obtain copper-manganese composite oxide (CuMnO).x Finally, 600mg CuMnO x After mechanical stirring with 900 mg SiO2, the mixture was calcined in an air muffle furnace at 700 °C for 4 h to obtain the CuMnSi-1 catalyst.

[0081] 120 mg of CuMnSi-1 catalyst was mixed with 400 mg of quartz sand (30-40 mesh) and then loaded into the reaction tube of a fixed-bed reactor. A micro-injection pump was used to deliver 4.02 mL / h. -1 Anhydrous ethanol is pumped into a preheater at a flow rate of [missing information] to be preheated and vaporized. After mixing with carrier gas N2, it enters the reaction bed and is reacted at 280°C, atmospheric pressure, and a mass hourly space velocity of 66.1 h⁻¹. -1 The reaction was carried out under the specified conditions, and the results are shown in Table 5.

[0082] Example 16

[0083] 2.03 g Cu(NO3)2·3H2O, 4.12 g Mn(CH3COO)2·4H2O, and 4.84 g citric acid were dissolved in 25 mL of deionized water to form a mixed solution. Ammonia was added dropwise to adjust the pH to 6–7. The mixed solution was then continuously stirred at 80 °C to obtain a wet gel, which was then placed in a 120 °C oven for 24 h to obtain a dry gel. The dry gel was then calcined in an air muffle furnace at 800 °C for 4 h and cooled to room temperature to obtain copper-manganese composite oxide (CuMnO). x Finally, 600mg CuMnO x After mechanical stirring with 900 mg Al2O3, the mixture was calcined in an air muffle furnace at 700 °C for 4 h to obtain the CuMnAl-1 catalyst.

[0084] 120 mg of CuMnAl-1 catalyst was mixed with 400 mg of quartz sand (30-40 mesh) and then loaded into the reaction tube of a fixed-bed reactor. A micro-injection pump was used to deliver 4.02 mL / h. -1 Anhydrous ethanol is pumped into a preheater at a flow rate of [missing information] to be preheated and vaporized. After mixing with carrier gas N2, it enters the reaction bed and is reacted at 280°C, atmospheric pressure, and a mass hourly space velocity of 66.1 h⁻¹. -1 The reaction was carried out under the specified conditions, and the results are shown in Table 5.

[0085] Example 17

[0086] 2.03 g Cu(NO3)2·3H2O, 4.12 g Mn(CH3COO)2·4H2O, and 4.84 g citric acid were dissolved in 25 mL of deionized water to form a mixed solution. Ammonia was added dropwise to adjust the pH to 6–7. The mixed solution was then continuously stirred at 80 °C to obtain a wet gel, which was then placed in a 120 °C oven for 24 h to obtain a dry gel. The dry gel was then calcined in an air muffle furnace at 800 °C for 4 h and cooled to room temperature to obtain copper-manganese composite oxide (CuMnO). x Finally, 600mg CuMnO x After mechanical stirring with 900 mg CeO2, the mixture was calcined in an air muffle furnace at 700 °C for 4 h to obtain the CuMnCe-1 catalyst.

[0087] 120 mg of CuMnTi-1 and CuMnCe-1 catalysts were mixed with 400 mg of quartz sand (30-40 mesh) and loaded into the reaction tube of a fixed-bed reactor. A micro-injection pump was used to deliver 4.02 mL / h of the mixture. -1 Anhydrous ethanol is pumped into a preheater at a flow rate of [missing information] to be preheated and vaporized. After mixing with carrier gas N2, it enters the reaction bed and is reacted at 280°C, atmospheric pressure, and a mass hourly space velocity of 66.1 h⁻¹. -1 The reaction was carried out under the specified conditions, and the results are shown in Table 5.

[0088] Table 5. Ethanol dehydrogenation performance of catalysts supported by different metal oxides

[0089]

[0090] In summary, we explored the effects of different metal oxide supports on the reaction system. We investigated TiO2, SiO2, Al2O3, and CeO2 as supports, and found that their catalytic performance was better than that of copper-manganese spinel (CuMn2O4, Table 7). Finally, we used TiO2 as the support and prepared a supported copper-manganese composite oxide catalyst (Example 1) by adjusting the pH with ammonia, using a sol-gel method combined with mechanical mixing.

[0091] Example 18

[0092] 1.32 g Cu(NO3)2·3H2O, 1.34 g Mn(CH3COO)2·4H2O, and 2.11 g citric acid were dissolved in 25 mL of deionized water to form a mixed solution. Ammonia was added dropwise to adjust the pH to 6–7. The mixed solution was then continuously stirred at 80 °C to obtain a wet gel, which was then placed in a 120 °C oven for 24 h to obtain a dry gel. The dry gel was then calcined in an air muffle furnace at 800 °C for 4 h and cooled to room temperature to obtain a copper-manganese composite oxide (CuMnO). x Finally, 600mg CuMnO xAfter mechanical stirring with 900 mg TiO2, the mixture was calcined in an air muffle furnace at 700 °C for 4 h to obtain the CuMnTi-7 catalyst.

[0093] 120 mg of CuMnTi-7 catalyst was mixed with 400 mg of quartz sand (30-40 mesh) and then loaded into the reaction tube of a fixed-bed reactor. A micro-injection pump was used to deliver 4.02 mL / h. -1 Anhydrous ethanol is pumped into a preheater at a flow rate of [missing information] to be preheated and vaporized. After mixing with carrier gas N2, it enters the reaction bed and is reacted at 280°C, atmospheric pressure, and a mass hourly space velocity of 66.1 h⁻¹. -1 The reaction was carried out under the specified conditions, and the results are shown in Table 6.

[0094] Example 19

[0095] 2.01 g Cu(NO3)2·3H2O, 1.02 g Mn(CH3COO)2·4H2O, and 2.39 g citric acid were dissolved in 25 mL of deionized water to form a mixed solution. Ammonia was added dropwise to adjust the pH to 6–7. The mixed solution was then continuously stirred at 80 °C to obtain a wet gel, which was then placed in a 120 °C oven for 24 h to obtain a dry gel. The dry gel was then calcined in an air muffle furnace at 800 °C for 4 h and cooled to room temperature to obtain a copper-manganese composite oxide (CuMnO). x Finally, 600mg CuMnO x After mechanical stirring with 900 mg TiO2, the mixture was calcined in an air muffle furnace at 700 °C for 4 h to obtain the CuMnTi-8 catalyst.

[0096] 120 mg of CuMnTi-1 and CuMnTi-8 catalysts were mixed with 400 mg of quartz sand (30-40 mesh) and loaded into the reaction tube of a fixed-bed reactor. A micro-injection pump was used to deliver 4.02 mL / h of the mixture. -1 Anhydrous ethanol is pumped into a preheater at a flow rate of [missing information] to be preheated and vaporized. It is then mixed with carrier gas N2 and enters the reaction bed. The reaction proceeds at 280°C, atmospheric pressure, and a mass hourly space velocity (HHSV) of 66.1 h⁻¹. -1 The reaction was carried out under the specified conditions, and the results are shown in Table 6.

[0097] Table 6. Ethanol dehydrogenation performance of catalysts with different copper-manganese molar ratios

[0098]

[0099] Summary: The effect of different copper-manganese molar ratios on the reaction system was explored. Copper:manganese (molar ratio) of 1:2 (CuMnTi-1), 1:1 (CuMnTi-7), and 2:1 (CuMnTi-8) were investigated. Compared with the catalyst with a copper-manganese molar ratio of 1:2, the catalytic performance of the other two metal molar ratios was slightly lower, which was speculated to be related to the number of metal active sites. Therefore, we finally used ammonia water to adjust the pH sol-gel method combined with mechanical mixing to prepare a supported copper-manganese composite oxide catalyst (i.e., Example 1).

[0100] Example 20

[0101] 800 mg CuO was placed in an air muffle furnace and calcined at 800 °C for 4 h, then cooled to room temperature. After that, 600 mg CuO and 900 mg TiO2 were mechanically stirred and calcined in an air muffle furnace at 700 °C for 4 h to obtain the CuO / TiO2 catalyst.

[0102] 120 mg of CuO / TiO2 catalyst was mixed with 400 mg of quartz sand (30-40 mesh) and then loaded into the reaction tube of a fixed-bed reactor. A micro-injection pump was used to deliver 4.02 mL / h of the mixture. -1 Anhydrous ethanol is pumped into a preheater at a flow rate of [missing information] to be preheated and vaporized. After mixing with carrier gas N2, it enters the reaction bed and is reacted at 280°C, atmospheric pressure, and a mass hourly space velocity of 66.1 h⁻¹. -1 The reaction was carried out under the specified conditions, and the results are shown in Table 7.

[0103] Example 21

[0104] 800 mg Mn2O3 was placed in an air muffle furnace and calcined at 800 °C for 4 h. After cooling to room temperature, 600 mg Mn2O3 and 900 mg TiO2 were mechanically stirred and calcined in an air muffle furnace at 700 °C for 4 h to obtain the Mn2O3 / TiO2 catalyst.

[0105] 120 mg of Mn2O3 / TiO2 catalyst was mixed with 400 mg of quartz sand (30-40 mesh) and then loaded into the reaction tube of a fixed-bed reactor. A micro-injection pump was used to deliver 4.02 mL / h of the mixture. -1 Anhydrous ethanol is pumped into a preheater at a flow rate of [missing information] to be preheated and vaporized. After mixing with carrier gas N2, it enters the reaction bed and is reacted at 280°C, atmospheric pressure, and a mass hourly space velocity of 66.1 h⁻¹. -1 The reaction was carried out under the specified conditions, and the results are shown in Table 7.

[0106] Example 22

[0107] 0.54 g CuO and 1.06 g Mn2O3 were mixed and calcined in an air muffle furnace at 800 °C for 4 h. After cooling to room temperature, a mixture of 600 mg CuO and Mn2O3 and 900 mg TiO2 was mechanically stirred and calcined in an air muffle furnace at 700 °C for 4 h. After cooling to room temperature, the CuO+Mn2O3 / TiO2 catalyst was obtained.

[0108] 120 mg of CuO+Mn2O3 / TiO2 catalyst was mixed with 400 mg of quartz sand (30-40 mesh) and loaded into the reaction tube of a fixed-bed reactor. A micro-injection pump was used to deliver 4.02 mL / h of the mixture. -1 Anhydrous ethanol is pumped into a preheater at a flow rate of [missing information] to be preheated and vaporized. After mixing with carrier gas N2, it enters the reaction bed and is reacted at 280°C, atmospheric pressure, and a mass hourly space velocity of 66.1 h⁻¹. -1 The reaction was carried out under the specified conditions, and the results are shown in Table 7.

[0109] Example 23

[0110] 2.42 g Cu(NO3)2·3H2O, 4.90 g Mn(CH3COO)2·4H2O and 3.85 g citric acid were dissolved in 30 mL of deionized water and stirred until homogeneous. 20 mL of anhydrous ethanol was added dropwise, and stirring was continued for 3 h after the addition was complete. The resulting mixed solution was placed in a freeze dryer for freeze drying. After freeze drying, the resulting solid was placed in a muffle furnace and calcined at 500 °C for 4 h in air atmosphere. After cooling to room temperature, CuMn2O4 catalyst was obtained.

[0111] 48 mg of CuMn2O4 catalyst was mixed with 400 mg of quartz sand (30-40 mesh) and then loaded into the reaction tube of a fixed-bed reactor. A micro-injection pump was used to deliver 4.02 mL / h. -1 Anhydrous ethanol is pumped into a preheater at a flow rate of [missing information] to be preheated and vaporized. After mixing with carrier gas N2, it enters the reaction bed and is reacted at 280°C, atmospheric pressure, and a mass hourly space velocity of 66.04 h⁻¹. -1 The reaction was carried out under the specified conditions, and the results are shown in Table 7.

[0112] Example 24

[0113] 2.01 g Cu(NO3)2·3H2O, 1.02 g Mn(CH3COO)2·4H2O, and 2.39 g citric acid were dissolved in 25 mL of deionized water to form a mixed solution. Ammonia was added dropwise to adjust the pH to 6-7. The mixed solution was then continuously stirred at 80 °C to obtain a wet gel, which was then placed in a 120 °C oven for 24 h to obtain a dry gel. The dry gel was then calcined in an air muffle furnace at 800 °C for 4 h and cooled to room temperature to obtain a copper-manganese composite oxide catalyst.

[0114] 48mg CuMnO x The catalyst was mixed with 400 mg of quartz sand (30-40 mesh) and then loaded into the reaction tube of a fixed-bed reactor. A micro-injection pump was used to deliver 4.02 mL / h. -1 Anhydrous ethanol is pumped into a preheater at a flow rate of [missing information] to be preheated and vaporized. After mixing with carrier gas N2, it enters the reaction bed and is reacted at 280°C, atmospheric pressure, and a mass hourly space velocity of 66.04 h⁻¹. -1 The reaction was carried out under the specified conditions, and the results are shown in Table 7.

[0115] Example 25

[0116] 72 mg of anatase TiO2, 120 mg of CuMnTi-1, and 400 mg of quartz sand (30-40 mesh) were mixed and loaded into the reaction tube of a fixed-bed reactor. A micro-injection pump was used to deliver 4.02 mL / h. -1 Anhydrous ethanol is pumped into a preheater at a flow rate of [missing information] to be preheated and vaporized. After mixing with carrier gas N2, it enters the reaction bed and is reacted at 280°C, atmospheric pressure, and a mass hourly space velocity of 44.03 h⁻¹. -1 and 66.1h -1 The reaction was carried out under the specified conditions, and the results are shown in Table 7. In addition, the ethanol dehydrogenation performance of different methods and catalysts with different compositions is summarized, and the results are shown in Table 8.

[0117] Table 7. Ethanol dehydrogenation performance of each component in CuMnTi-1 catalyst

[0118]

[0119] Table 8. Summary of Ethanol Dehydrogenation Performance Using Different Methods and Catalysts with Different Compositions

[0120]

[0121] Summary: The effects of each component of the catalyst on the reaction system were explored, specifically CuO / TiO2, Mn2O3 / TiO2, CuO+Mn2O3 / TiO2, CuMn2O4, and CuMnO. x And TiO2. Compared with the CuMnTi-1 catalyst, the reaction activity of CuO alone or Mn2O3 supported on TiO2 is very low, with ethanol conversion rates of 72.5%, 10.2%, and 1.5%, respectively; the ethanol conversion rate of mechanically mixed CuO and Mn2O3 supported on TiO2 catalyst (CuO+Mn2O3 / TiO2) is 38.3%; when CuMn2O4 and TiO2 are used as catalysts at a mass ratio of 40% of CuMnTi-1 catalyst, the results show that the ethanol conversion rate is 1.5% when TiO2 is used as the catalyst, and 35.8% when CuMn2O4 spinel is used as the catalyst. Therefore, the active component of CuMnTi-1 catalyst is CuMnO4.x Furthermore, the copper-manganese composite oxide CuMnO x Copper oxide (CuO), manganese trioxide (Mn2O3), copper manganese spinel (CuMn2O4), and support TiO2 play a synergistic role in the reaction system.

[0122] Compared with the copper-manganese spinel catalyst in Chinese invention patent CN 118976511 A, under the same reaction conditions, the CuMnTi-1 of this invention improves the utilization rate of copper and manganese, enhances catalytic performance, reduces the amount of copper-manganese spinel required in the reaction, and lowers the overall cost of catalyst preparation.

[0123] Note: Copper-manganese composite oxide CuMnO x It is composed of copper-manganese spinel CuMn2O4 and CuO, Mn2O3.

[0124] The present invention is not limited to the specific technical solutions described in the above embodiments. All technical solutions formed by equivalent substitutions are within the scope of protection claimed by the present invention.

Claims

1. The application of a supported heterogeneous catalyst of oxide synergistic with copper-manganese spinel in the oxygen-free dehydrogenation of ethanol to acetaldehyde, characterized in that: The supported heterogeneous catalyst is prepared as follows: The copper-manganese composite oxide CuMnOx is composed of copper-manganese spinel CuMn2O4, CuO, and Mn2O3; Cu(NO3)2·3H2O, Mn(CH3COO)2·4H2O, and citric acid are dissolved in deionized water to form a mixed solution, and ammonia is added dropwise to adjust the pH to 6-7; the wet gel obtained by continuously stirring the mixed solution is placed in an oven and dried to obtain a dry gel; then the dry gel is calcined in an air muffle furnace and cooled to room temperature to obtain the copper-manganese composite oxide CuMnOx. x The copper-manganese metal molar ratio is 1:2; finally, the copper-manganese composite oxide and anatase titanium dioxide are mechanically stirred and then calcined in an air muffle furnace to obtain the CuMnTi-1 catalyst, with the copper-manganese composite oxide having a mass fraction of 40%.

2. The application of the oxide-copper-manganese spinel supported heterogeneous catalyst according to claim 1 in the oxygen-free dehydrogenation of ethanol to acetaldehyde, characterized in that: The copper-manganese composite oxide catalyst CuMnTi-1 was mixed evenly with quartz sand and placed in the reaction tube of a fixed-bed reactor. Anhydrous ethanol was vaporized in the preheater using a micro-pump, with N2 as the carrier gas; the reaction conditions were: reaction temperature 280 °C, atmospheric pressure, and anhydrous ethanol flow rate 4.02 mL·h. -1 Mass hourly space velocity 66.1 h -1 .

3. The application of the oxide-copper-manganese spinel supported heterogeneous catalyst according to claim 1 in the oxygen-free dehydrogenation of ethanol to acetaldehyde, characterized in that: 2.03 g Cu(NO3)2·3H2O, 4.12 g Mn(CH3COO)2·4H2O, and 4.84 g citric acid were dissolved in 25 mL of deionized water to form a mixed solution. Ammonia was added dropwise to adjust the pH to 6-7. The mixed solution was then continuously stirred at 80 °C to obtain a wet gel, which was then placed in a 120 °C oven for 24 h to obtain a dry gel. The dry gel was then calcined in an air muffle furnace at 800 °C for 4 h and cooled to room temperature to obtain the copper-manganese composite oxide CuMnO. x Finally, CuMnO x After mechanical stirring with TiO2, the mixture was calcined in an air muffle furnace at 700 °C for 4 h to obtain the CuMnTi-1 catalyst. 120 mg of CuMnTi-1 catalyst was mixed with 400 mg of quartz sand and loaded into the reaction tube of a fixed-bed reactor. A micro-injection pump was used to deliver 4.02 mL·h. -1 Anhydrous ethanol was pumped into a preheater at a flow rate of [missing information], vaporized, mixed with carrier gas N2, and then entered the reaction bed. The reaction was carried out at 280 °C, atmospheric pressure, and a mass hourly space velocity (HHSV) of 66.1 h⁻¹. -1 The reaction takes place under the specified conditions.

4. The application of the oxide-copper-manganese spinel supported heterogeneous catalyst according to claim 3 in the oxygen-free dehydrogenation of ethanol to acetaldehyde, characterized in that: The ethanol conversion rate to acetaldehyde via ethanol dehydrogenation was 72.5%, the acetaldehyde selectivity was 95.0%, and the space-time yield of acetaldehyde based on copper-manganese composite oxides was 43.5 h. -1 .

5. The application of the oxide-copper-manganese spinel supported heterogeneous catalyst according to claim 1 in the oxygen-free dehydrogenation of ethanol to acetaldehyde, characterized in that: The supported copper-manganese composite oxide catalyst was calcined in air at 700-800 °C.

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