A method for preparing adiponitrile by catalytic dehydration of adipamide
The preparation of adiponitrile by catalyzing the dehydration of adipase amine with a supported palladium-based catalyst solves the problem of high temperature and high cost in the dehydration reaction of amide compounds in the prior art, and realizes the efficient, green and safe preparation of adiponitrile.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- HEBEI UNIV OF TECH
- Filing Date
- 2023-10-18
- Publication Date
- 2026-07-24
Smart Images
Figure CN117402080B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of organic synthesis, and specifically to a method for preparing adiponitrile by catalytic dehydration of adipamide. Background Technology
[0002] Adiponitrile is a colorless, oily liquid and an intermediate in the production of hexamethylenediamine, primarily used to generate nylon 66. In addition, it can be used as a rubber accelerator and rust inhibitor, an additive in detergents, a spinning solvent for ternary copolymers and other textile auxiliaries, an ester plasticizer, and an extractant for aromatic hydrocarbon extraction, making it a very important chemical raw material.
[0003] Currently, the dehydration reaction processes for amide compounds primarily use toluene or chlorobenzene as solvents and phosgene, thionyl chloride, etc., as dehydrating agents. These dehydrating agents have drawbacks such as high cost, high toxicity, difficult post-processing, and severe environmental pollution. Without dehydrating agents, the dehydration of amides to nitriles requires high reaction temperatures (>160℃).
[0004] CN112495362B reports a catalyst composed of metal oxides, additives, and a support for the catalytic dehydration of amides to produce adiponitriles. The catalyst involves continuously and uniformly feeding adipamide into a fixed bed in liquid form for dehydration to produce adiponitriles. The optimal reaction temperature is 340℃. In practical applications, the reaction temperature is too high, the catalyst preparation is complex, and the energy consumption is significant.
[0005] CN111116415A reports the use of one or more of the following as catalysts and dehydrating agents to catalyze the dehydration of adipamide to prepare adiponitrile. The yield of adiponitrile in this reaction is as high as 95%, but the catalyst is difficult to recover and cannot be reused.
[0006] Therefore, it is particularly urgent to design a catalyst that is highly active, reproducible, stable, easy to separate and recycle, environmentally friendly, and has a low reaction temperature to further reduce production costs for the dehydration of adipamide to prepare adiponitrile. Summary of the Invention
[0007] The purpose of this invention is to address the shortcomings of current technologies by providing a method for the catalytic dehydration of adipamide to prepare adiponitrile. This method uses adipamide as a raw material and, without the use of a dehydrating agent, employs a supported palladium-based catalyst to catalytically dehydrate adiponitrile at ambient pressure and 50-65°C for 1-4 hours. This invention is simple to operate, has mild reaction conditions, achieves a raw material conversion rate of up to 100%, and an adiponitrile yield of up to 99.2%. The only reaction byproduct is water, resulting in high atom utilization. The catalyst is simple to prepare, easy to recover, and environmentally friendly.
[0008] The technical solution of this invention is:
[0009] A method for preparing adiponitrile by catalytic dehydration of adipamide, the method comprising the following steps:
[0010] Add adipamide, solvent, and catalyst to a reactor and react at atmospheric pressure and 30-80℃ for 0.5-8 hours to obtain adiponitrile.
[0011] For every 1 mmol of hexamethylenediamide, add 5-25 ml of solvent; for every 1 mmol of hexamethylenediamide, add 0.05-0.5 g of catalyst.
[0012] The catalyst is a supported palladium-based catalyst, and its composition includes an active metal and a support.
[0013] The active metal is Pd; the catalyst support is acid-modified SiO2; and the active metal loading is 0.1 wt%-5 wt%.
[0014] The solvent is acetonitrile:water = 1:3-3:1.
[0015] The preferred reaction temperature is 50-65℃, and the reaction time is 1-4h.
[0016] The preferred material ratio is as follows: 10-20 ml of solvent is added for every 1 mmol of adipamide; 0.1-0.5 g of catalyst is added for every 1 mmol of adipamide.
[0017] The preparation process of the catalyst is as follows:
[0018] a. Add the catalyst support SiO2 to the phosphoric acid solution, stir at room temperature for 10-24 hours, wash with deionized water until neutral, dry at 60-110℃, and then calcine at 400-600℃ in air atmosphere for 5-10 hours to obtain acid-modified SiO2 support.
[0019] In this case, 0.2–5 g of carrier is added to every 10 ml of phosphoric acid solution;
[0020] b. Dissolve the palladium salt in dilute hydrochloric acid and sonicate for 10-20 minutes to prepare an impregnation solution;
[0021] c. According to the loading amount, add the support prepared in step a to the impregnation solution, stir and let it stand at room temperature for 8-12 hours, dry it at 70-120℃, and then calcine it in air at 300-600℃ for 1-10 hours to obtain the supported palladium-based catalyst.
[0022] The concentration of the phosphoric acid solution is 5wt%-15wt%.
[0023] The concentration of the dilute hydrochloric acid is 0.01-0.1 mol / ml; 0.002-0.1 g of palladium salt is added to every 1 mL of dilute hydrochloric acid;
[0024] The palladium salt is one of palladium chloride, palladium acetate, palladium bromide, palladium nitrate, sodium tetrachloropalladium, and potassium chloropalladium.
[0025] The beneficial effects of this invention are:
[0026] (1) This invention achieves the catalytic dehydration of adipamide to adiponitrile under low temperature and atmospheric pressure conditions (atmospheric pressure, low temperature of 50-65℃, short time of 1-4h) by using a supported palladium-based catalyst without the need for a dehydrating agent. Under the reaction system of this invention, the raw material conversion rate can reach 100% and the adiponitrile yield can reach 99.2%.
[0027] (2) The reaction operation is simple, the process is easy to control, and the catalyst preparation process is simple, which greatly reduces the production cost;
[0028] (3) The only byproduct of the reaction is water, the atom utilization rate is high, and the whole reaction system is green and safe.
[0029] (4) After the reaction is completed, the reaction solution can be centrifuged and separated. The catalyst settles at the bottom and can be recycled, showing good application prospects. Attached Figure Description
[0030] Figure 1 The GC spectrum of adiponitrile in the reaction solution of Example 1.
[0031] Figure 2 MS spectrum of adiponitrile in the reaction solution of Example 1 Detailed Implementation
[0032] The specific embodiments of the present invention will be further described in detail below through specific examples.
[0033] Example 1
[0034] Add 2g of SiO2 to 20ml of 5wt% phosphoric acid solution and mix well. Then stir at room temperature for 24 hours, wash with deionized water until neutral, dry at 100℃ for 24 hours, and then calcine at 550℃ for 6 hours to obtain acid-modified SiO2.
[0035] Weigh 0.014g of PdCl2 and add it to 3ml of 0.05mol / ml dilute hydrochloric acid. After dissolving completely, sonicate for 15min to prepare an impregnation solution. Then weigh 1g of the prepared support (acid-modified SiO2) and add it to the impregnation solution. Stir evenly with a glass rod and let the impregnated catalyst stand at room temperature for 12h. Then dry it in a 120℃ drying oven for 12h. Finally, calcine it at 400℃ for 3h to obtain the catalyst 0.5wt% Pd / SiO2.
[0036] Adipamide (1 mmol, 0.144 g) was added to acetonitrile (10 ml) and water (10 ml), then placed in a round-bottom flask and stirred until the adipamide was fully dissolved. Then, 0.2 g of catalyst was added, and the reaction was carried out in a 60°C water bath for 2 hours. After cooling to room temperature, the reaction solution was centrifuged, and the supernatant was analyzed by gas chromatography. The conversion rate of adipamide was 100%, and the yield of adiponitrile was 86.3%.
[0037] like Figure 1 The image shows the gas chromatogram (GC) of the reaction solution. The product with a retention time of 11.498 min is acetamide produced by the hydration of acetonitrile, and the product with a retention time of 18.042 min is adiponitrile. Figure 2 The mass spectrometry (MS) spectrum shows that the substance matched by the mass spectrometer has the same molecular weight as adiponitrile, and the mass-charge ratio analysis also confirms that the product is the same as adiponitrile. Therefore, the GC-MS spectrum indirectly confirms that the product is adiponitrile.
[0038] Example 2
[0039] The other steps are the same as in Example 1, except that the reaction temperature is 80°C and the solvent ratio is acetonitrile:water = 15ml:5ml. The reaction result is that the conversion rate of adipamide is 95.4% and the yield of adiponitrile is 88.2%.
[0040] Example 3
[0041] The other steps were the same as in Example 1, except that the reaction temperature was 50°C. The reaction result was an adipamide conversion rate of 80.2% and an adiponitrile yield of 75.3%.
[0042] Example 4
[0043] The other steps are the same as in Example 1, except that the phosphoric acid solution concentration is 10 wt%. The reaction result is that the conversion rate of adipamide is 100%, and the yield of adiponitrile is 97.3%.
[0044] Example 5
[0045] The other steps were the same as in Example 1, except that the phosphoric acid solution concentration was 10 wt%, the catalyst dosage was 0.1 g, and the reaction time was 4 hours. The reaction result was that the conversion rate of adipamide was 100%, and the yield of adiponitrile was 89.6%.
[0046] Example 6
[0047] The other steps were the same as in Example 1, except that the phosphoric acid solution concentration was 10 wt%, the solvent ratio was acetonitrile:water = 5 ml:15 ml, and the reaction time was 4 hours. The reaction results showed that the conversion rate of adipamide was 100%, and the yield of adiponitrile was 81.4%.
[0048] Example 7
[0049] The other steps were the same as in Example 1, except that the phosphoric acid solution concentration was 15 wt%. The reaction result was a 100% conversion rate of adipamide and a 90.4% yield of adiponitrile.
[0050] Example 8
[0051] The other steps were the same as in Example 1, except that the palladium salt was palladium acetate and the catalyst dosage was 0.1 g. The reaction results showed that the conversion rate of adipamide was 67.3% and the yield of adiponitrile was 55.2%.
[0052] Example 9
[0053] The other steps were the same as in Example 1, except that the palladium salt was palladium acetate. The reaction results showed an adipamide conversion rate of 85.2% and an adiponitrile yield of 79.2%.
[0054] Example 10
[0055] The other steps were the same as in Example 1, except that the palladium loading was 0.9 wt% and the solvent ratio was acetonitrile:water = 15 ml:5 ml. The reaction result showed that the conversion rate of adipamide was 100% and the yield of adiponitrile was 99.2%.
[0056] Example 11
[0057] The other steps were the same as in Example 1, except that the palladium loading was 0.9 wt% and the reaction temperature was 50 °C. The reaction result was a 100% conversion of adipamide and a 94.3% yield of adiponitrile.
[0058] As can be seen from the above examples, the reaction system is simple to operate, the reaction conditions are mild, and the adiponitrile yield is high. The catalyst used is simple to prepare, has good activity and selectivity, and is easily separated from the reaction system. Analysis of the data in the examples shows that the optimal catalyst is a 0.9% Pd / SiO2 catalyst. Under the experimental conditions of adding 1 mmol of adipamide, 0.2 g of 0.9% Pd / SiO2 catalyst, 15 ml of acetonitrile, and 5 ml of water at 60°C for 2 hours, the reaction system exhibits high conversion and yield, achieving a 100% conversion of adipamide and a 99.2% yield of adiponitrile.
[0059] Matters not covered in this invention are common knowledge.
Claims
1. A method for preparing adiponitrile by catalytic dehydration of adipamide, characterized in that the method includes the following steps: Add adipamide, solvent and catalyst to a reactor and react at atmospheric pressure and 30-80℃ for 0.5-8 hours to obtain adiponitrile; For every 1 mmol of hexamethylenediamide, add 5-25 ml of solvent; for every 1 mmol of hexamethylenediamide, add 0.05-0.5 g of catalyst. The catalyst is a supported palladium-based catalyst, and its composition includes an active metal and a support. The active metal is Pd; the catalyst support is acid-modified SiO2; the active metal loading is 0.1wt%-0.9wt%; The solvent is acetonitrile and water; the volume ratio is acetonitrile:water = 1:3-3:1; The method for preparing the catalyst includes the following steps: a. Add the catalyst support SiO2 to the phosphoric acid solution, stir at room temperature for 10-24 hours, wash with deionized water until neutral, dry at 60-110℃, and then calcine at 400-600℃ in air atmosphere for 5-10 hours to obtain acid-modified SiO2 support. 0.2-5g of carrier is added to every 10ml of phosphoric acid solution; b. Dissolve the palladium salt in dilute hydrochloric acid and sonicate for 10-20 minutes to prepare an impregnation solution; According to the loading amount, the support prepared in step a is added to the impregnation solution, stirred and allowed to stand at room temperature for 8-12 hours, dried at 70-120℃, and then calcined in air at 300-600℃ for 1-10 hours to obtain the supported palladium-based catalyst.
2. The method for preparing adiponitrile by catalytic dehydration of adipamide as described in claim 1, characterized in that the reaction temperature is preferably 50-65℃ and the reaction time is 1-4h.
3. The method for preparing adiponitrile by catalytic dehydration of adipamide as described in claim 1, characterized in that the material ratio is 10-20 ml of solvent per 1 mmol adipamide; and 0.1-0.5 g of catalyst per 1 mmol adipamide.
4. The method for preparing adiponitrile by catalytic dehydration of adipamide as described in claim 1, characterized in that the catalyst... In the preparation, the concentration of the phosphoric acid solution is 5wt%-15wt%; The concentration of the dilute hydrochloric acid is 0.01-0.1 mol / ml; 0.002-0.1 g of palladium salt is added to every 1 mL of dilute hydrochloric acid.
5. The method for preparing adiponitrile by catalytic dehydration of adipamide as described in claim 1, characterized in that the catalyst... In the preparation, the palladium salt is one of palladium chloride, palladium acetate, palladium bromide, palladium nitrate, sodium tetrachloropalladium, and potassium chloropalladium.