A catalyst for synthesizing 2,6-diethylphenylaminoethyl propyl ether and application thereof

Abstract

The application belongs to the field of preparation and application of catalysts, and provides a preparation method of a catalyst for synthesizing 2,6-diethyl anilino ethyl propyl ether, wherein the catalyst uses copper and aluminum salt as a metal source and an alkali solution as a precipitant, a copper-aluminum spinel catalyst is prepared by using a chemical co-precipitation method, and the catalyst is applied to the synthesis reaction of 2,6-diethyl anilino ethyl propyl ether which is an important intermediate of propamocarb. After process optimization, the application has the advantages of strong reaction selectivity, high yield, good color and high purity of the product, easy availability of the reaction raw material, simple operation, simple post-treatment, and repeated cyclic use of the copper-aluminum spinel catalyst, and not only meets the requirements of green chemistry, but also has important significance for energy saving and emission reduction.

Description

Technical Field

[0001] This invention relates to the field of catalysis technology, specifically to a method for preparing a catalyst for synthesizing 2,6-diethylaniline ethyl propyl ether and its application. Background Technology

[0002] Alkyl aromatic amines are very important fine chemical intermediates, widely used in pesticides, dyes, plastics, and other fields. Pretilachlor is a highly selective, low-toxicity, broad-spectrum herbicide that effectively inhibits or eliminates weeds without harming rice. 2,6-Diethylaniline ethyl propyl ether is an important intermediate in the synthesis of the herbicide pretilachlor. Currently, the main methods for synthesizing 2,6-diethylaniline ethyl propyl ether include:

[0003] 1) Patent CN 1044784741 provides a method for synthesizing 2,6-diethylaniline ethyl propyl ether, an intermediate of propachlor. 2,6-Diethylaniline is reacted with chloroethyl propyl ether under alkaline conditions to synthesize 2,6-diethylaniline ethyl propyl ether. However, this method generates a large amount of organic wastewater, causing serious environmental pollution.

[0004] 2) Patent CN 115894259 describes the alkylation reaction of 2,6-diethylaniline and ethylene glycol monopropyl ether under the action of a noble metal catalyst. However, the noble metal catalyst is expensive and difficult to use for large-scale industrial production.

[0005] 3) Patent CN 102408352A provides a method for synthesizing 2,6-diethylaniline ethyl propyl ether, an intermediate of propachlor. Using ethylene glycol monopropyl ether and 2,6-diethylaniline as raw materials, and toluene as a solvent, the reaction is carried out in a four-necked flask, achieving a single-step yield of up to 94%. However, this method requires toluene as a solvent, making post-processing difficult and potentially causing environmental pollution. Furthermore, the reaction time is too long, hindering industrial-scale production.

[0006] 4) Article 1004-0935(2000)02-0112-02 provides a method for synthesizing 2,6-diethylaniline ethyl propyl ether, an intermediate of propachlor. Using ethylene glycol monopropyl ether and 2,6-diethylaniline as raw materials, the yield can reach 89% under a special catalyst. However, this reaction requires the introduction of H2, which increases the risk of operation; the catalyst raw materials are expensive, making it difficult to apply to industrial production.

[0007] Traditional metal oxide catalysts are limited by their poor structure, few active sites, and poor stability, making it difficult to effectively solve the problem of low catalytic efficiency. Spinel, with its unique metal-oxygen tetrahedral and metal-oxygen octahedral layered structure, exhibits excellent superconductivity, luminescence, and catalytic activity, and is widely used in ceramics, superconductivity, and catalysis. This invention shows that spinel-type metal oxides exhibit excellent catalytic performance due to the tunability of their structure, composition, phase, and valence state. This invention attempts to use spinel as a catalyst to catalyze the synthesis of 2,6-diethylaniline ethylpropyl ether. Summary of the Invention

[0008] To address the problems of high cost and poor stability of traditional metal oxides, this invention prepares a CuAl₂O₄ spinel catalyst that is inexpensive and readily available, has a simple preparation process, high selectivity, high yield, and is easy to use. Using 2,6-diethylaniline and ethylene glycol monopropyl ether as raw materials, the important intermediate 2,6-diethylaniline-ethylpropyl ether for the synthesis of propachlor is catalytically produced under the action of the CuAl₂O₄ spinel catalyst. Ethylene glycol monopropyl ether, as an N-alkylation reagent for 2,6-diethylaniline, produces only H₂O as a byproduct, exhibiting non-toxicity and environmental friendliness.

[0009] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0010] The specific process for synthesizing 2,6-diethylaniline ethyl propyl ether using CuAl2O4 catalysis is as follows:

[0011] The CuAl₂O₄ catalyst was packed in a fixed-bed reactor and reacted at a pressure of 0–5 MPa, a temperature of 200–300 °C, a molar ratio of monopropyl ether to 2,6-diethylaniline of 1:2–5, and a mass hourly space velocity of 0.07–0.87 h⁻¹. -1 2,6-Diethylaniline ethylpropyl ether was synthesized under the following conditions.

[0012] The specific steps for preparing the CuAl2O4 catalyst are as follows:

[0013] (1) Dissolve copper nitrate and aluminum nitrate in an aqueous solution at a molar ratio of 1:0.5-5, and then use alkali as a precipitant to completely precipitate the mixed salt solution at a pH of 10.

[0014] (2) The obtained precipitate is aged, and then the aged coprecipitate is filtered and washed using a vacuum pump;

[0015] (3) The filter cake obtained by filtration is dried under vacuum at a constant temperature;

[0016] (4) The solid obtained in step (3) is placed in a muffle furnace and calcined at high temperature to obtain a metal oxide catalyst with a spinel structure;

[0017] (5) Mix spinel structure metal oxide catalyst powder, dilute nitric acid and pseudoboehmite in a mass ratio of (1-10):(1-5):1, stir, extrude and dry, and finally prepare granular catalyst (diameter about 1-2 mm).

[0018] Furthermore, the preferred molar ratio of copper nitrate to aluminum nitrate is 1:2.

[0019] Furthermore, the alkali used in step (1) is one or a combination of several of the following: Na2CO3, NaOH, K2CO3, KOH, and ammonia solution. NaOH is preferred as the alkali.

[0020] Furthermore, the calcination temperature in the muffle furnace is 500–1100℃; the calcination time is 3–10 hours. Preferably, the calcination temperature is 900℃; the calcination time is 6 hours.

[0021] The catalyst powder, dilute nitric acid, and boehmite were mixed and stirred at a ratio of (1-10):(1-5):1 (wt%).

[0022] Furthermore, the preferred synthesis conditions in the synthesis method are: a reaction pressure of 3 MPa, a reaction temperature of 250–260 °C, and a mass hourly space velocity of 0.67 h⁻¹. -1 The molar ratio of monopropyl ether to 2,6-diethylaniline is 1:5.

[0023] This invention relates to catalysts for the synthesis of 2,6-diethylaniline ethyl propyl ether, which have the following characteristics:

[0024] 1) Compared to some precious metal catalysts, the spinel-type catalyst prepared by this invention uses inexpensive and readily available raw materials, significantly reducing production costs. The catalyst requires no activation treatment before use, making operation simple and convenient. Using ethylene glycol monopropyl ether as the alkylating agent, the only byproduct is H₂O, demonstrating green and environmentally friendly properties. Compared to chloroethylpropyl ether and bromoethylpropyl ether as alkylating agents, this method avoids the generation of organic wastewater, protects the environment, reduces treatment costs, and is more suitable for industrial production.

[0025] 2) The reaction of synthesizing 2,6-diethylaniline ethylpropyl ether is catalyzed by a self-made spinel catalyst. It has the advantages of strong reaction selectivity, high yield, simple operation, easy post-processing, good product color and high purity. The reaction can be carried out on a large scale by fixed bed catalysis, and it also has certain important significance in terms of greening, energy saving and emission reduction. Attached Figure Description

[0026] Figure 1 The graph shows the effect of the molar ratio of copper nitrate to aluminum nitrate on the catalytic effect.

[0027] Figure 2 The figure shows the effect of different precipitants on the catalytic effect.

[0028] Figure 3 The graph shows the effect of different calcination temperatures on the catalytic effect.

[0029] Figure 4 The graph shows the effect of calcination time on the catalytic effect.

[0030] Figure 5 This is a graph showing the effect of reaction pressure on catalytic performance.

[0031] Figure 6 This is a graph showing the effect of reaction temperature on the catalytic effect.

[0032] Figure 7 The graph shows the effect of mass space velocity on catalytic performance.

[0033] Figure 8 The effect of the ether-amine ratio on the catalytic effect.

[0034] Figure 9 Stability test of CuAl2O4 spinel.

[0035] Figure 10 For stability testing of amorphous copper and aluminum metal oxides.

[0036] Figure 11 The XRD pattern of CuAl2O4 is shown below.

[0037] The diffraction peaks point to the crystal planes (220), (311), (400), (422), (511), (440), (620), and (533), proving that the catalyst has a spinel structure.

[0038] Figure 12 The image shows the full XPS spectrum of CuAl2O4; the metal ion in the catalyst is Cu. 2+ Al 3+ .

[0039] Figure 13 The image shows the Cu 2P XPS plot of CuAl2O4;

[0040] The binding energies corresponding to the main peaks are 934.49 eV and 954.30 eV, representing the Cu 2p³ / ² and Cu 2p¹ / ² orbitals, respectively; Sat is a satellite peak of Cu 2p. Copper is associated with Cu. 2+ The valence state exists in spinel.

[0041] Figure 14 The image shows the Al 2P XPS plot of CuAl2O4.

[0042] The low binding energy of 73.99 eV and the high binding energy of 77.51 eV in the figure represent Al atoms located in spinel tetrahedra and spinel octahedra, respectively. 3+ . Detailed Implementation

[0043] Example 1

[0044] (1) Dissolve copper nitrate and aluminum nitrate in water at a molar ratio of 1:2, and then use NaOH as a precipitant to completely precipitate the mixed salt solution at pH 10.

[0045] (2) The obtained precipitate was aged for 24 hours, and then the aged co-precipitate was filtered and washed using a vacuum pump.

[0046] (3) The filter cake obtained by filtration is dried under vacuum at a constant temperature of 80℃;

[0047] (4) The solid obtained in step (3) is placed in a muffle furnace and calcined at 900°C for 6 hours to obtain a metal oxide catalyst with a spinel structure;

[0048] (5) A spinel-structured metal oxide catalyst, dilute nitric acid and pseudoboehmite were mixed in a mass ratio of 6:3:1 to prepare a granular catalyst.

[0049] (6) 9g of the granular catalyst prepared in step (5) was loaded into a fixed-bed reaction tube and reacted under N2 pressure of 3MPa, temperature of 260℃, molar ratio of monopropyl ether to 2,6-diethylaniline of 1:3, and mass hourly space velocity of 0.67h. -1 2,6-Diethylaniline ethyl propyl ether was synthesized under specific conditions. The yield of the target product, 2,6-diethylaniline ethyl propyl ether, was as high as 90.9%, with a selectivity of 93.5%.

[0050] Example 2

[0051] Other procedures are the same as in Example 1. Example 2 explores the effect of catalysts prepared with different molar ratios of copper nitrate and aluminum nitrate on the catalytic effect of the reaction, as detailed in Table 1. Figure 1 As shown.

[0052] Table 1. Effect of catalysts prepared with different molar ratios of copper nitrate and aluminum nitrate on the catalytic effect of the reaction.

[0053]

[0054]

[0055] from Figure 9It can be seen that when the molar ratio of copper nitrate to aluminum nitrate is 1:2, the catalyst has a better spinel crystal form. Under the action of the catalyst with this ratio, the yield and selectivity of 2,6-diethylaniline ethyl propyl ether are both high.

[0056] Example 3

[0057] Other operations are the same as in Example 1. Example 2 explores the effect of the type of alkali used in the preparation of the co-precipitate on the catalytic effect, as detailed in Table 2. Figure 2 As shown.

[0058] Table 2. Effect of the type of alkali used in the preparation of co-precipitates on the catalytic effect of the catalyst.

[0059] alkali 2,6-Diethylaniline ethylpropyl ether selectivity Yield of 2,6-diethylaniline ethylpropyl ether Sodium carbonate 86.5％ 78.9％ Sodium hydroxide 93.5％ 90.9％ Potassium carbonate 89.7％ 82.9％ potassium hydroxide 91.2％ 86.4％ ammonia 94.5％ 81.6％

[0060] From Table 2, Figure 2 It is evident that different precipitants have a significant impact on the catalytic performance of the catalyst. Strong alkalis such as NaOH...

[0061] When KOH is used as a precipitant, the catalyst exhibits good catalytic activity and selectivity for the target product; however, when a weak base ammonia solution is used as a precipitant, the catalyst activity is relatively low. The highest yield of 2,6-diethylaniline ethyl propyl ether is achieved when NaOH is used as the precipitant.

[0062] Example 4

[0063] Other operations are the same as in Example 1. Example 4 explores the effect of the calcination temperature of the coprecipitate on the catalytic effect, as shown in Table 3. Figure 3 As shown.

[0064] Table 3. Effect of calcination temperature of coprecipitate on catalytic effect

[0065] Calcination temperature 2,6-Diethylaniline ethylpropyl ether selectivity Yield of 2,6-diethylaniline ethylpropyl ether 700℃ 96.3％ 68％ 800℃ 92.3％ 80.8％ 900℃ 93.5％ 90.9％ 1000℃ 88.6％ 85.7％ 1100℃ 85.7％ 76％

[0066] From Table 3, Figure 3 It is evident that as the calcination temperature increases, the catalyst crystal structure becomes more perfect, and the catalyst activity improves. When the temperature exceeds 900℃, the catalyst activity decreases; excessively high calcination temperatures may cause catalyst structural collapse, preventing the surface active centers from fully contacting the reactants, thus deteriorating the conversion rate and selectivity. Therefore, 900℃ was selected as the optimal calcination temperature.

[0067] Example 5

[0068] Other operations are the same as in Example 1. Example 5 explores the effect of calcination time of the coprecipitate on the catalytic effect, as shown in Table 4. Figure 4 As shown.

[0069] Table 4. Effect of calcination time of coprecipitate on catalytic effect

[0070] Calcination time, h 2,6-Diethylaniline ethylpropyl ether selectivity Yield of 2,6-diethylaniline ethylpropyl ether 3 95.1％ 71.9％ 4 92.5％ 79.9％ 5 93.1％ 84.1％ 6 93.5％ 90.9％ 7 92.7％ 90.6％

[0071] From Table 4, Figure 4 It is known that thorough calcination can improve the crystal structure of the catalyst, thereby enhancing its catalytic activity. The yield of 2,6-diethylaniline ethyl propyl ether was optimal when calcined for 6 hours. Further extending the calcination time did not significantly alter the catalytic performance; therefore, 6 hours was chosen as the optimal calcination time.

[0072] Example 6

[0073] Other operations are the same as in Example 1. The effect of pressure in the fixed-bed reactor on the catalytic effect is investigated, as shown in Table 5. Figure 5 As shown.

[0074] Table 5. Effect of pressure in the fixed-bed reactor on catalytic efficiency

[0075] Reaction pressure, MPa 2,6-Diethylaniline ethylpropyl ether selectivity Yield of 2,6-diethylaniline ethylpropyl ether 0 85.6％ 71.2％ 1 88.4％ 77.4％ 2 90.2％ 83.3％ 3 93.5％ 90.9％ 4 91.9％ 90.2％

[0076] From Table 5, Figure 5 It is known that under low pressure conditions, the feedstock 2,6-diethylaniline is prone to disproportionation, resulting in feedstock waste. Introducing an appropriate amount of N2 as a protective gas not only promotes the conversion of monopropyl ether but also reduces the formation of disproportionation impurities and improves selectivity. However, excessively high pressure easily promotes the formation of disubstituted products, leading to decreased selectivity. The highest yield of 2,6-diethylaniline ethylpropyl ether was achieved at a pressure of 3 MPa.

[0077] Example 7

[0078] Other operations are the same as in Example 1. The effect of temperature in the fixed-bed reactor on the catalytic effect is investigated, as shown in Table 6. Figure 6 As shown.

[0079] Table 6. Effect of temperature in fixed-bed reactor on catalytic efficiency

[0080] Reaction temperature, °C 2,6-Diethylaniline ethylpropyl ether selectivity Yield of 2,6-diethylaniline ethylpropyl ether 230 98.7％ 78.3％ 240 98.2％ 83.7％ 250 97.6％ 92.9％ 260 93.5％ 90.9％ 270 85.1％ 84％

[0081] Depend on Figure 6 It is known that the higher the temperature, the higher the conversion rate of the raw materials, but the side reactions are also enhanced under high temperature conditions, leading to a decrease in the selectivity of the reaction. When the temperature is 250℃, the yield of 2,6-diethylaniline ethyl propyl ether is 92.9%, and the selectivity is 97.6%.

[0082] Example 8

[0083] Other operations are the same as in Example 1. The effect of mass hourly space velocity (MHV) in the fixed-bed reactor on the catalytic effect is investigated, as shown in Table 7. Figure 7 As shown.

[0084] Table 7. Effect of mass hourly space velocity (MHV) on catalytic efficiency in fixed-bed reactors

[0085] <![CDATA[Mass space velocity, h -1 > 2,6-Diethylaniline ethylpropyl ether selectivity Yield of 2,6-diethylaniline ethylpropyl ether 0.27 82.6％ 82.6％ 0.47 88.8％ 88.2％ 0.67 93.5％ 90.9％ 0.87 94.1％ 88.8％ 1.07 97.1％ 80.8％

[0086] Depend on Figure 7 It is known that the higher the mass hourly space velocity (WHSV), the lower the conversion rate of monopropyl ether. At low WHSVs, the reactants have more sufficient contact with the catalyst, resulting in a higher conversion rate; however, excessively low WHSVs can cause the product 2,6-diethylaniline ethylpropyl ether to remain on the catalyst and continue to react with monopropyl ether to form a disubstituted product. When WHSV = 0.67 h⁻¹ -1 The yield of 2,6-diethylaniline ethyl propyl ether was 90.9%, with a selectivity of 93.5%.

[0087] Example 9

[0088] Other procedures were the same as in Example 1. The effect of the molar ratio of monopropyl ether to 2,6-diethylaniline on the catalytic effect was investigated, as shown in Table 8. Figure 8 As shown.

[0089] Table 8. Effect of the molar ratio of monopropyl ether to 2,6-diethylaniline on catalytic performance

[0090] Ether-amine molar ratio 2,6-Diethylaniline ethylpropyl ether selectivity Yield of 2,6-diethylaniline ethylpropyl ether 1:3 90.7％ 81.8％ 1:3.5 91.2％ 86.7％ 1.4 93.5％ 90.9％ 1:4.5 93.7％ 91.6％ 1:5 94.1％ 92.3％

[0091] Depend on Figure 8 It can be seen that the conversion rate of monopropyl ether increases with the increase of the ether-amine molar ratio. The excess 2,6-diethylaniline slightly reduces the amount of disubstituted products, and the selectivity of 2,6-diethylaniline-ethylpropyl ether also increases. When the ether-amine ratio is 1:5, the yield of 2,6-diethylaniline-ethylpropyl ether is 92.3%, and the selectivity is 94.1%.

[0092] Example 10

[0093] At a pressure of 3 MPa N2, a temperature of 250 °C, a molar ratio of monopropyl ether to 2,6-diethylaniline of 1:3, and a mass hourly space velocity of 0.67 h⁻¹, the following conditions were met: -1 2,6-Diethylaniline ethyl propyl ether was synthesized under specific conditions, and its stability to CuAl₂O₄ was investigated. Figure 9 As shown, after 100 hours of reaction, there was no obvious inactivation, indicating good stability.

[0094] Comparative Example

[0095] Preparation of spinel-free CuAl₂O₄ metal oxide: Copper nitrate and aluminum nitrate were dissolved in water in a molar ratio of 1:2, and NaOH was used as a precipitant to completely precipitate the mixed salt solution at pH 10. The resulting precipitate was aged for 24 h, and then the aged co-precipitate was filtered and washed using a vacuum pump. The filter cake obtained from filtration was dried under vacuum at a constant temperature of 80 °C. The resulting solid was calcined in a muffle furnace at 300 °C for 3 h to obtain a spinel-free copper-aluminum metal oxide catalyst. The catalyst was prepared under N₂ pressure of 3 MPa, temperature of 250 °C, a molar ratio of monopropyl ether to 2,6-diethylaniline of 1:3, and a mass hourly space velocity of 0.67 h⁻¹. -1 2,6-Diethylaniline ethyl propyl ether was synthesized under the following conditions. The yield of the target product, 2,6-diethylaniline ethyl propyl ether, was 66.4%, with a selectivity of 87.7%. Its stability was studied, such as... Figure 10 As shown, significant deactivation occurred after 65 hours of reaction, indicating poor stability.

[0096] The results show that the catalytic effect and stability of copper-aluminum metal oxides without spinel structure are much lower than those with spinel structure.

[0097] The above describes the preparation and application of the catalyst for synthesizing 2,6-diethylaniline ethyl propyl ether according to the present invention. It should be noted that the above embodiments should not be considered as limitations on the present invention, and the scope of protection of the present invention should be determined by the scope defined in the claims. For those skilled in the art, several improvements and modifications can be made without departing from the spirit and scope of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for synthesizing 2,6-diethylaniline ethyl propyl ether, characterized in that: The catalyst was packed in a fixed-bed reactor and subjected to an environment with a pressure of 0–5 MPa, a temperature of 200–300 °C, a molar ratio of monopropyl ether to 2,6-diethylaniline of 1:2–5, and a mass hourly space velocity of 0.07–0.87 h⁻¹. -1 2,6-Diethylaniline ethylpropyl ether was synthesized under the following conditions; The catalyst preparation steps are as follows: (1) Dissolve soluble copper salt and soluble aluminum salt in an aqueous solution at a molar ratio of 1:0.5 to 5, and then use alkali as a precipitant to completely precipitate the mixed salt solution under alkaline conditions and collect the precipitate; (2) The obtained precipitate is aged, and then the aged coprecipitate is filtered, washed and dried using a vacuum pump; (3) The dried solid from step (2) is placed in a muffle furnace and calcined at high temperature to obtain a copper aluminum oxide catalyst with a spinel structure.

2. The method according to claim 1, characterized in that: Step (3) The calcination temperature is 500-1100 ℃; the calcination time is 3-10 h.

3. The method according to claim 1, characterized in that: The molar ratio of the soluble copper salt to the soluble aluminum salt is 1:2; the alkali is one or more of Na2CO3, NaOH, K2CO3, KOH, or an ammonia solution.

4. The method according to claim 1, characterized in that: The alkali is NaOH; the calcination temperature is 900℃; and the calcination time is 6 hours.

5. The method as described in claim 1, characterized in that: First, the copper aluminum oxide catalyst with spinel structure is shaped by mixing the catalyst, dilute nitric acid and boehmite in a certain proportion to prepare granular catalyst for use in a fixed bed reaction tube. The mass ratio of catalyst, dilute nitric acid and boehmite is (1-10): (1-5):

1.

6. The method as described in claim 1, characterized in that: The pressure in the fixed-bed reaction tube is 3 MPa.

7. The method as described in claim 1, characterized in that: The temperature in the fixed-bed reactor was 250℃, and the mass hourly space velocity (HHSV) was 0.67 h⁻¹. -1 .

8. The method as described in claim 1, characterized in that: The molar ratio of monopropyl ether to 2,6-diethylaniline is 1:5.

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