Process for the synthesis of adiponitrile by selective ammoxidation of cyclohexene oxide

Abstract

The application provides a method for synthesizing adiponitrile by selective ammoxidation of epoxycyclohexane. The purpose of the application is to simulate and optimize the process of synthesizing adiponitrile by one-step direct ammoxidation of epoxycyclohexane, and to develop a new type of multiphase composite metal vanadium-based oxide catalyst, which is composed of Co a V b P c Mo d MNOx / TiO2, the active elements of which include vanadium element V, cobalt element Co, phosphorus element P and molybdenum element Mo, M is an auxiliary metal element (Mn, Cr, Fe or Ni), N is an alkali metal (Na, K or Cs); the value range of a is 0.2-1.2; the value range of b is 0.8-1.5; the value range of c is 0.1-0.23; the value range of d is 0.07-0.35; x is the proportion of oxygen atoms required to meet the oxidation state of metal. The catalyst has the advantages of simple preparation, good cycle stability, high yield and the like. The yield and product purity of adiponitrile are improved, the energy consumption in the production process of adiponitrile is reduced, and a breakthrough is realized in the production technology of adiponitrile.

Description

Technical Field

[0001] This invention belongs to the field of selective ammonia oxidation catalyst preparation and application technology, specifically involving a method for preparing a vanadium-based catalyst for the synthesis of adiponitrile and its application. Background Technology

[0002] Adiponitrile is an intermediate of nylon 66 and a major raw material for the production of hexamethylenediamine. Nylon 66, also known as polyhexamethylenediamine, is a major type of polyamide plastic, possessing high chemical stability, elasticity, strength, and a range of advantages including light resistance, water resistance, and high-temperature resistance. Its main applications include: producing radial tire cords, mechanical accessories such as gears and lubricating bearings, fishing nets, carpet yarn, nylon stockings, swimwear, and automotive seat belts; and replacing non-ferrous metal materials in machine housings and automotive engine blades. In today's rapidly developing automotive industry, nylon 66 tire cord fabric, as a major tire skeleton material, is gradually becoming the most important downstream product of adiponitrile. Its strength, lifespan, and fatigue resistance are far superior to cord fabrics made from rayon and polyester fibers, and it also has wide applications in rubber conveyor belts, carpet yarn, and engineering plastics.

[0003] In recent years, with the rapid development of the nylon 66 industry, the demand for adiponitrile, a raw material, for the intermediate hexamethylenediamine has gradually increased. Adiponitrile accounts for about 45% of the production cost of nylon 66.

[0004] There are four main methods for producing adiponitrile: acrylonitrile electrolytic dimerization, adipic acid catalytic amination, caprolactam degradation followed by hydrolysis, and butadiene method. This invention comprehensively compares these three processes based on technological advancement, product quality, and production cost. The one-step method using a heterogeneous vanadium-based catalyst to synthesize adiponitrile from cyclohexane oxide is the most competitive and promising. Currently, one literature report describes a route for preparing adiponitrile from cyclohexane oxide, which requires 3.5 times the amount of iodine in the presence of ammonia and acetonitrile as co-solvents to achieve a 70% adiponitrile yield. This process suffers from significant iodine pollution and high costs, making it unsuitable for industrial production. In contrast, the method described above, using cyclohexane oxide as a substrate in the presence of a vanadium-based catalyst, under oxygen and ammonia atmospheres, and with the addition of an auxiliary agent, achieves an adiponitrile yield as high as 84.8%. The adiponitrile synthesis technology proposed in this invention has advantages over the butadiene method and the iodine catalysis method, including the use of inexpensive heterogeneous metal catalysts that can be recycled, low energy consumption in one-step reaction, low raw material cost, no pollution, high product quality and yield, short process route, relatively low investment, and advanced technology. It has great industrial application value.

[0005] [References]

[0006] 1.Ravindra R.Jadhav and Krishnacharya G.Akamanchi.*Chem.Lett.2013,42,162-164. Summary of the Invention

[0007] This invention provides a novel type of heterogeneous vanadium-based catalyst for a method of selectively oxidizing cyclohexane oxide to adipiconitrile.

[0008] According to the present invention, a method for selective ammoxidation of cyclohexane oxide to synthesize adiponitrile is described, using cyclohexane oxide as raw material, acetonitrile as solvent, and oxygen and ammonia atmosphere, under the action of a heterogeneous vanadium-based catalyst, the yield of adiponitrile is as high as 84.8%.

[0009] According to the present invention, the multiphase vanadium-based catalyst is a multi-component vanadium-based catalyst with a composition of Co. a V b P c Mo d MNOx / TiO2 contains vanadium (V), cobalt (Co), phosphorus (P), and molybdenum (Mo); M is an auxiliary metal element (Mn, Cr, Fe, or Ni), and N is an alkali metal (Na, K, or Cs).

[0010] The value of a ranges from 0.8 to 1.2;

[0011] The value of b ranges from 0.2 to 1.3;

[0012] The value of c ranges from 0.5 to 2.0;

[0013] The value of d ranges from 0.07 to 0.35;

[0014] x represents the proportion of oxygen atoms required to satisfy the oxidation state of the metal.

[0015] According to the present invention, the multi-component multiphase vanadium-based catalyst further includes an auxiliary metal M and an alkali metal N; the auxiliary metal element M is selected from one or more of manganese Mn, chromium Cr, iron Fe and nickel Ni, preferably a combination of Ni and Mn; the alkali metal element N is selected from one or more of sodium Na, potassium K and cesium Cs, preferably K.

[0016] According to the present invention, the multi-component multiphase vanadium-based catalyst is prepared by impregnating a corresponding metal salt solution onto an anatase support, and the specific steps are as follows:

[0017] 1) Disperse or dissolve the required amount of carrier precursor and corresponding metal salt precursor in an acidic solution with a mass concentration of 10-30%, stir evenly, and age at 40-80°C for 12-48 hours to obtain solution A;

[0018] 2) Dissolve the vanadium precursor in oxalic acid solution and stir at room temperature for 1-5 hours to obtain solution B.

[0019] 3) Under aging temperature and stirring, solution B is added to solution A to obtain a catalyst precursor solid, which is then filtered, washed, and dried; and calcined at high temperature (300–800℃) in an aerobic atmosphere for 2–12 minutes.

[0020] h yielded a multi-component, multiphase vanadium-based catalyst product.

[0021] The vanadium source is a vanadium compound, preferably a vanadium oxide;

[0022] The cobalt source is a cobalt compound, preferably a cobalt oxide;

[0023] The molybdenum source is a molybdenum compound, preferably an oxide of molybdenum;

[0024] The phosphorus source is a phosphorus compound, preferably a soluble phosphate or phosphoric acid;

[0025] The molar ratio of the vanadium source, cobalt source, molybdenum source, and phosphorus source is 1:(0.2-1.2):(0.05-0.25):(0.3-2.0), preferably 1:(0.4-1.0):(0.1-0.23):(0.5-1.6), and the molar amount of each metal raw material is calculated based on the molar amount of the element contained in its metal.

[0026] According to the present invention, the auxiliary metal element source is a salt or oxide containing nickel (Ni), manganese (Mn), iron (Fe) and chromium (Cr), such as nickel chloride, manganese chloride, manganese oxide, iron oxide, ferrous oxide, ferric chloride, ferrous chloride, chromium chloride, and chromium oxide.

[0027] According to the present invention, the alkali metal element source is a soluble alkali metal salt, preferably an alkali metal hydrochloride, alkali metal sulfate, or alkali metal nitrate; the molar ratio of the vanadium source, auxiliary metal element source, and alkali metal element source is 1:(0.01-0.2):(0.02-0.35), preferably 1:(0.01-0.15):(0.04-0.25), and the molar amount of each metal raw material is calculated based on the molar amount of the metal component elements contained therein.

[0028] According to the present invention, the multi-component multiphase vanadium-based catalyst is a supported multi-component vanadium catalyst, wherein the catalyst support is selected from one of TiO2, CeO2, ZrO2, Nb2O5, Ta2O5, MgO, Al2O3, SiO2, hydroxyapatite, and hydrotalcite, with TiO2 being the most preferred.

[0029] According to the present invention, the vanadium loading is one of 2wt%, 4wt%, 6wt%, 8wt%, and 10wt%, with 4wt% being the most preferred.

[0030] According to the present invention, the reaction process for the selective ammoxidation of cyclohexane oxide to adiponitrile is as follows:

[0031] Cyclohexane oxide (1 mmol), catalyst (50 mg), and acetonitrile (2 mL) were added sequentially to 10 mL reaction tubes. The reaction tubes were then placed in a high-pressure reactor and sealed. A certain amount of oxygen was introduced to replace the oxygen three times, and leaks were checked. Then, 0.5 MPa O2 and 0.5 MPa NH3 were introduced respectively, and the reactor was placed in an 80℃ oil bath and stirred at 550 r / min for 12 h. After the reaction was completed, the reactor was allowed to cool naturally to room temperature. The pressure was slowly released and 20 mg of naphthalene was added as an internal standard. Then, 2 mL of methanol was added for dilution. The mixture was stirred, sonicated, mixed evenly, and centrifuged. The supernatant was taken for GC / GC-MS analysis.

[0032] According to the present invention, the catalytic performance of the selective ammoxidation synthesis of adiponitrile from cyclohexane oxide is related to the amount of catalyst used. Too low a amount will affect the activity of the catalytic reaction, while too high a amount will increase the cost of the catalyst; therefore, it is necessary to select an appropriate amount. To ensure the activity of the catalyst while reducing its cost, the molar ratio of V content to substrate in the catalyst is in the range of 1–10 mol%, preferably in the range of 2–5 mol%.

[0033] According to the present invention, the method for selectively oxidizing cyclohexane oxide to synthesize adiponitrile uses toluene, acetonitrile, tert-amyl alcohol, 1,2-dichloroethane, dimethyl sulfoxide (DMSO), N,N-dimethylformamide (DMF), n-heptane, tetrahydrofuran, and water as the reaction solvent, with acetonitrile being the most preferred.

[0034] According to the present invention, the method for selectively oxidizing cyclohexane oxide to adiponitrile involves a reaction temperature of 60–120°C and a reaction time of 4–24 h; the most preferred reaction temperature is 80–100°C, and the most preferred reaction time is 10–16 h. The product obtained after the reaction is adiponitrile, and the yield and selectivity of the product are determined by chromatographic internal standard method.

[0035] According to the present invention, the method for selective ammoxidation of cyclohexane oxide to synthesize adiponitrile is a heterogeneous catalytic system. The heterogeneous vanadium-based catalyst can be recycled, and its activity does not decrease significantly after more than 8 cycles.

[0036] According to the present invention, when the substrate is scaled up to the kilogram level, under standard conditions, the selectivity of adiponitrile can reach 84.8% after 12 hours of reaction. This scaled-up experimental result demonstrates the potential application value of the reaction system.

[0037] This method has high catalytic oxidation efficiency, good selectivity, and high product yield. It not only greatly improves atom utilization but is also economical and environmentally friendly, and has a promising application prospect.

[0038] This catalyst boasts advantages such as simple preparation, good cycle stability, and high yield. It aims to improve the yield and purity of adiponitrile, reduce energy consumption in the adiponitrile production process, and achieve a technological breakthrough in adiponitrile production.

[0039] The present invention has the following advantages and effects compared with the prior art:

[0040] (1) The heterogeneous, inexpensive vanadium-based catalyst used in this invention requires readily available raw materials and simple preparation conditions, making it very easy to synthesize in large quantities. This catalyst exhibits good recycling performance. After simple filtration, washing, and drying, it can be reused without altering its catalytic activity or selectivity.

[0041] (2) This invention is completely different from existing butadiene technologies abroad (as shown in Formula 1), and represents a novel process route: starting from cyclohexane oxide, adiponitrile is directly prepared by one-pot ammoxidation. Compared to the butadiene method, this route has advantages such as a one-step reaction, the use of a recyclable multiphase inexpensive metal catalyst, and the elimination of the need for hydrogen cyanide. The adiponitrile yield of this route can reach 84.8%, and the route is simple, green, and pollution-free, making it more promising for industrial production.

[0042]

[0043] (3) Compared with other existing production processes (as shown in Table 1), the acrylonitrile electrolysis production process has a wide range of raw material sources and features low energy consumption, high yield, and high product quality. However, due to the high market price of acrylonitrile and small production scale, it has been gradually phased out. The butadiene method has a complex production process, serious equipment corrosion, large investment, and requires a large amount of hydrogen cyanide, so it has been basically phased out. The direct cyanidation method has the characteristics of low raw material cost, no pollution, high product quality and yield, short process route, and relatively low investment. The process is advanced, and no mature process has been developed in China. The adipic acid catalytic ammoniation method has been basically phased out due to the high cost of adipic acid.

[0044] In summary, no mature adiponitrile production process has been developed domestically, making adiponitrile production a key factor restricting the development of my country's Nylon 66 industry. By comparing industrialized adiponitrile production processes worldwide and considering the current raw material market situation, the one-step ammonia oxidation method of cyclohexane oxide is considered to have advantages such as novel and reliable technology, low cost, low pollution, recoverable catalyst, high product quality, and high yield, making it a key focus for adiponitrile production process development in my country.

[0045] Table 2 Comparison of Adiponitrile Production Processes

[0046] project Acrylonitrile process adipic acid method Butadiene process One-step ammonia oxidation method Source of raw materials widely widely widely widely Raw material costs high high generally Low process generally complex generally Simple Energy consumption high generally lower Low Mass production Small Moderate size Large scale Large scale Product Quality generally generally generally high yield lower lower higher high Environmental friendly High pollution Pollution Pollution Low pollution invest higher lower lower lower Detailed Implementation

[0047] The following examples will help to understand the present invention, but the scope of the present invention is not limited thereto.

[0048] Example 1

[0049] Catalyst preparation: Co a V b P c Mo d Ox / TiO2

[0050] The multi-component, multiphase vanadium-based catalyst is prepared by impregnating a corresponding metal salt solution onto anatase support, and the specific steps are as follows:

[0051] 1) Disperse or dissolve the required amount of carrier precursor and corresponding metal salt precursor in an acidic solution with a mass concentration of 10-30%, stir evenly, and age at 40-80°C for 12-48 hours to obtain solution A;

[0052] 2) Dissolve the vanadium precursor in oxalic acid solution and stir at room temperature for 1-5 hours to obtain solution B.

[0053] 3) Under aging temperature and stirring, solution B is added to solution A to obtain the catalyst precursor, which is then sprayed and dried; and calcined at high temperature in an oxygen atmosphere at 300-800℃ for 2-12 hours to obtain the multi-component multiphase vanadium-based catalyst product.

[0054] The vanadium source is a vanadium compound, preferably a vanadium oxide;

[0055] The cobalt source is a cobalt compound, preferably a cobalt oxide;

[0056] The molybdenum source is a molybdenum compound, preferably an oxide of molybdenum;

[0057] The phosphorus source is a phosphorus compound, preferably a soluble phosphate or phosphoric acid;

[0058] The molar ratio of the vanadium source, cobalt source, molybdenum source, and phosphorus source is 1:(0.2-1.2):(0.05-0.25):(0.3-2.0), preferably 1:(0.4-1.0):(0.1-0.23):(0.5-1.6), and the molar amount of each metal raw material is calculated based on the molar amount of the element contained in its metal.

[0059] Example 2

[0060] Cyclohexane oxide (1 mmol), Catalyst catalyst (50 mg), and acetonitrile (2 mL) were added sequentially to 10 mL reaction tubes. The reaction tubes were then placed in a high-pressure reactor and sealed. The atmosphere inside the reactor was purged with oxygen three times to check for leaks. Then, 0.5 MPa O2 and 0.5 MPa NH3 were added respectively. The reactor was placed in an 80 °C oil bath and stirred at 550 r / min for 12 h. After the reaction was completed, the reactor was allowed to cool naturally to room temperature. The pressure was slowly released and 20 mg naphthalene was added as an internal standard. Then, 2 mL of methanol was added for dilution. The mixture was stirred, sonicated, and thoroughly mixed. The mixture was then centrifuged, and the supernatant was taken for GC / GC-MS analysis.

[0061] Example 3

[0062] Catalyst A (4wt% Co) 0.4 VP 0.5 Mo 0.1 Ni 0.01 K 0.04 O 2.69 Preparation of / TiO2)

[0063] 36g of vanadium pentoxide and 13g of cobalt trioxide were dissolved in 500mL of an aqueous solution containing 100g of oxalic acid. 23g of an 85wt% phosphoric acid solution was added, and the mixture was stirred for 2 hours. Then, 7.8g of ammonium molybdate was slowly added, and the mixture was stirred for another 2 hours. After stirring, 0.513g of nickel chloride and 1.18g of potassium chloride were added, and the mixture was stirred for 3 hours. The molar ratio of the added metal elements was V:Co:P:Mo:Ni:K = 1:0.4:0.5:0.1:0.01:0.04.

[0064] Anatase (TiO2) support was added to the above solution and stirred until homogeneous. After impregnation at 40°C for 48 hours, the solution was spray-dried to obtain the catalyst precursor. The precursor was then placed in a muffle furnace and heated to 600°C for 12 hours. After cooling to room temperature, vanadium-based catalyst A supported on titanium dioxide (where 4 wt% is the percentage of vanadium relative to the support) was obtained and bottled for later use.

[0065] Example 4

[0066] Catalyst B (4wt% CoVP) 1.6 Mo 0.23Ni 0.15 K 0.25 O 2.72 Preparation of / TiO2)

[0067] 36g of vanadium pentoxide and 32.8g of cobalt trioxide were dissolved in 500mL of an aqueous solution containing 100g of oxalic acid. 73g of an 85wt% phosphoric acid solution was added, and the mixture was stirred for 2 hours. Then, 17.8g of ammonium molybdate was slowly added, and the mixture was stirred for another 2 hours. After stirring, 7.7g of nickel chloride and 7.4g of potassium chloride were added, and the mixture was stirred for 3 hours. The molar ratio of the added metal elements was V:Co:P:Mo:Ni:K = 1:1:1.6:0.23:0.15:0.25.

[0068] Anatase (TiO2) support was added to the above solution and stirred until homogeneous. After impregnation at 40°C for 48 hours, the solution was spray-dried to obtain the catalyst precursor. The precursor was then placed in a muffle furnace and heated to 600°C for 12 hours. After cooling to room temperature, vanadium-based catalyst B supported on titanium dioxide (where 4 wt% is the percentage of vanadium relative to the support) was obtained and bottled for later use.

[0069] Example 5

[0070] Catalyst C (4wt% Co) 0.4 VP 0.5 Mo 0.1 Mn 0.01 K 0.04 O 2.69 Preparation of / TiO2)

[0071] 36g of vanadium pentoxide and 13g of cobalt trioxide were dissolved in 500mL of an aqueous solution containing 100g of oxalic acid. 23g of an 85wt% phosphoric acid solution was added, and the mixture was stirred for 2 hours. Then, 7.8g of ammonium molybdate was slowly added, and the mixture was stirred for another 2 hours. After stirring, 0.67g of manganese sulfate monohydrate and 1.18g of potassium chloride were added, and the mixture was stirred for 3 hours. The molar ratio of the added metal elements was V:Co:P:Mo:Ni:K = 1:0.4:0.5:0.1:0.01:0.04.

[0072] Anatase (TiO2) support was added to the above solution and stirred until homogeneous. After impregnation at 40°C for 48 hours, the solution was spray-dried to obtain the catalyst precursor. The precursor was then placed in a muffle furnace and heated to 600°C for 12 hours. After cooling to room temperature, vanadium-based catalyst C supported on titanium dioxide (where 4 wt% is the percentage of vanadium relative to the support) was obtained and bottled for later use.

[0073] Example 6

[0074] Catalyst D (4wt% CoVP) 1.6 Mo0.23 Mn 0.15 K 0.25 O 2.72 Preparation of / TiO2)

[0075] 36g of vanadium pentoxide and 32.8g of cobalt trioxide were dissolved in 500mL of an aqueous solution containing 100g of oxalic acid. 73g of an 85wt% phosphoric acid solution was added, and the mixture was stirred for 2 hours. Then, 17.8g of ammonium molybdate was slowly added, and the mixture was stirred for another 2 hours. After stirring, 10g of manganese sulfate monohydrate and 7.4g of potassium chloride were added, and the mixture was stirred for 3 hours. The molar ratio of the added metal elements was V:Co:P:Mo:Ni:K = 1:1:1.6:0.23:0.15:0.25.

[0076] Anatase (TiO2) support was added to the above solution and stirred until homogeneous. After impregnation at 40°C for 48 hours, the solution was spray-dried to obtain the catalyst precursor. The precursor was then placed in a muffle furnace and heated to 600°C for 12 hours. After cooling to room temperature, vanadium-based catalyst D supported on titanium dioxide (where 4 wt% is the percentage of vanadium relative to the support) was obtained and bottled for later use.

[0077] Example 7

[0078] Catalyst E (4wt% Co) 0.8 VP 1.2 Mo 0.15 Ni 0.05 K 0.14 O 2.52 Preparation of / TiO2 (abbreviated as 4wt%VOx / TiO2)

[0079] 36 g of vanadium pentoxide and 26.3 g of cobalt trioxide were dissolved in 500 mL of an aqueous solution containing 100 g of oxalic acid. Then, 54.8 g of an 85 wt% phosphoric acid solution was added, and the mixture was stirred for 2 hours. Next, 11.6 g of ammonium molybdate was slowly added, and the mixture was stirred for another 2 hours. After stirring, 2.57 g of nickel chloride and 4.13 g of potassium chloride were added, and the mixture was stirred for 3 hours. The molar ratio of the added metal elements was V:Co:P:Mo:Ni:K = 1:0.8:1.2:0.15:0.05:0.14. (4 wt% represents the percentage of vanadium relative to the carrier.)

[0080] Anatase (TiO2) support was added to the above solution and stirred until homogeneous. After impregnation at 40°C for 48 hours, the solution was spray-dried to obtain the catalyst precursor. The precursor was then placed in a muffle furnace and heated to 600°C for 12 hours. After cooling to room temperature, vanadium-based catalyst E supported on titanium dioxide (where 4 wt% is the percentage of vanadium relative to the support) was obtained and bottled for later use.

[0081] Examples 8-12

[0082] The process and conditions are the same as in Example 7, except that the amount of support added is different, and the catalyst (2wt%, 6wt%, 8wt%, 10wt%, 50wt% Co) is also different. 0.8 VP 1.2 Mo 0.15 Ni 0.05 K 0.14 Preparation of Ox / TiO2)

[0083] The titanium dioxide-supported vanadium-based catalyst was prepared according to the method of Example 7, with the only difference being the different loading amounts of vanadium relative to the support (where 2wt%, 6wt%, 8wt%, 10wt%, and 50wt% are the percentage contents of vanadium relative to the support). 50wt% VOx / TiO2 (i.e., a vanadium to support mass ratio of 1:1);

[0084] Examples 13-19

[0085] The titanium dioxide-supported vanadium-based catalyst was prepared according to the method of Example 3, with the same process and conditions as in Example 3, except that the type of support was different.

[0086] The support may be one of CeO2, ZrO2, Nb2O5, Ta2O5, MgO, Al2O3, or SiO2, VOx / CeO 2、 VOx / ZrO2, VOx / Nb2O5, VOx / Ta2O5, VOx / MgO, VOx / Al2O3, VOx / SiO2.

[0087] Example 20

[0088] Except for the different types of catalyst supports and vanadium loading, the catalyst activity evaluation was the same as in Example 2. The reaction conditions and catalytic reaction results are shown in Table 1. As can be seen from Table 1: 1) The type and doping ratio of metal may have a certain influence on catalytic activity (Examples 3-6); different choices of catalyst supports may lead to different final catalytic performance, among which TiO2 as a support has the highest catalytic activity (Examples 13-19); different V loading may lead to different catalytic activities, among which the catalytic activity is the highest when the V loading is 4wt% (Examples 7-12);

[0089] In summary, the type of catalyst support, the doping ratio of elements, the vanadium loading, the reaction temperature, and the reaction time all affect the efficiency of the catalytic oxidation of ammonia to adiponitrile by cyclohexane oxide.

[0090]

[0091] Table 1 Screening of conditions for the selective ammoxidation synthesis of adiponitrile from cyclohexane oxide

[0092] catalyst Conversion (%) Selectivity (%) Yield (%) Example 3 Catalyst A 100 60.8 60.8 Example 4 Catalyst B 100 77.7 77.7 Example 5 Catalyst C 100 75.3 75.3 Example 6 Catalyst D 100 83.7 83.7 Example 7 Catalyst E 100 84.8 84.8 Example 8 <![CDATA[2wt%VOx / TiO2]]> 96 78.4 75.3 Example 9 <![CDATA[6wt%VOx / TiO2]]> 100 80.3 80.3 Example 10 <![CDATA[8wt%VOx / TiO2]]> 100 78.9 78.9 Example 11 <![CDATA[10wt%VOx / TiO2]]> 94 74.5 70 Example 12 <![CDATA[VOx / TiO2(1:1)]]> 93 80.6 75 Example 13 <![CDATA[VOx / CeO2]]> 90 67 60.3 Example 14 <![CDATA[VOx / ZrO2]]> 92 73.4 67.5 Example 15 <![CDATA[VOx / Nb2O5]]> 77 81.8 63 Example 16 <![CDATA[VOx / Ta2O5]]> 89 57.1 50.8 Example 17 VOx / MgO 70 45.3 31.7 Example 18 <![CDATA[VOx / Al2O3]]> 84 64.4 54.1 Example 19 <![CDATA[VOx / SiO2]]> 100 55 55

[0093] Comparative Example 1

[0094] Preparation of 2wt% VOx / TiO2

[0095] 18g of vanadium pentoxide and 26.3g of cobalt trioxide were dissolved in 500mL of an aqueous solution containing 100g of oxalic acid. Then, 54.8g of an 85wt% phosphoric acid solution was added, and the mixture was stirred for 2 hours. Next, 11.6g of ammonium molybdate was slowly added, and the mixture was stirred for another 2 hours. After stirring, 2.57g of nickel chloride and 4.13g of potassium chloride were added, and the mixture was stirred for 3 hours. The molar ratio of the added metal elements was V:Co:P:Mo:Ni:K = 0.5:0.8:1.2:0.15:0.05:0.14. (2wt% represents the percentage of vanadium relative to the carrier.)

[0096] Anatase (TiO2) support was added to the above solution and stirred until homogeneous. After impregnation at 40°C for 48 hours, the solution was filtered, washed, spray-dried, and then dried to obtain the catalyst precursor. The precursor was then placed in a muffle furnace and calcined at 600°C for 12 hours. After cooling to room temperature, a vanadium-based catalyst E supported on titanium dioxide (where 2 wt% is the percentage of vanadium relative to the support) was obtained and bottled for later use.

[0097] Comparative Example 2

[0098] Catalyst E (4wt% Co) 0.8 VP 1.2 Mo 0.15 Ni 0.05 K 0.14 O 2.52 Preparation of / TiO2 (abbreviated as 4wt%VOx / TiO2)

[0099] 36 g of vanadium pentoxide and 26.3 g of cobalt trioxide were dissolved in 500 mL of an aqueous solution containing 100 g of oxalic acid. Then, 54.8 g of an 85 wt% phosphoric acid solution was added, and the mixture was stirred for 2 hours. Next, 11.6 g of ammonium molybdate was slowly added, and the mixture was stirred for another 2 hours. After stirring, 2.57 g of nickel chloride and 4.13 g of potassium chloride were added, and the mixture was stirred for 3 hours. The molar ratio of the added metal elements was V:Co:P:Mo:Ni:K = 1:0.8:1.2:0.15:0.05:0.14. (4 wt% represents the percentage of vanadium relative to the carrier.)

[0100] Anatase (TiO2) support was added to the above solution and stirred until homogeneous. After impregnation at 40°C for 48 hours, the solution was filtered, washed, spray-dried, and dried to obtain the catalyst precursor. The precursor was then placed in a muffle furnace and calcined at 600°C for 12 hours. After cooling to room temperature, vanadium-based catalyst E supported on titanium dioxide (where 4 wt% is the percentage of vanadium relative to the support) was obtained and bottled for later use.

[0101] Comparative Example 3

[0102] Preparation of 6wt% VOx / TiO2

[0103] 54 g of vanadium pentoxide and 26.3 g of cobalt trioxide were dissolved in 500 mL of an aqueous solution containing 100 g of oxalic acid. Then, 54.8 g of an 85 wt% phosphoric acid solution was added, and the mixture was stirred for 2 hours. Next, 11.6 g of ammonium molybdate was slowly added, and the mixture was stirred for another 2 hours. After stirring, 2.57 g of nickel chloride and 4.13 g of potassium chloride were added, and the mixture was stirred for 3 hours. The molar ratio of the added metal elements was V:Co:P:Mo:Ni:K = 1.5:0.8:1.2:0.15:0.05:0.14. (6 wt% represents the percentage of vanadium relative to the carrier.)

[0104] Anatase (TiO2) support was added to the above solution and stirred until homogeneous. After impregnation at 40°C for 48 hours, the solution was filtered, washed, spray-dried, and dried to obtain the catalyst precursor. The precursor was then placed in a muffle furnace and calcined at 600°C for 12 hours. After cooling to room temperature, a vanadium-based catalyst E supported on titanium dioxide (where 6 wt% is the percentage of vanadium relative to the support) was obtained and bottled for later use.

[0105] Comparative Example 4

[0106] Preparation of 8wt% VOx / TiO2

[0107] 72g of vanadium pentoxide and 26.3g of cobalt trioxide were dissolved in 500mL of an aqueous solution containing 100g of oxalic acid. Then, 54.8g of an 85wt% phosphoric acid solution was added, and the mixture was stirred for 2 hours. Next, 11.6g of ammonium molybdate was slowly added, and the mixture was stirred for another 2 hours. After stirring, 2.57g of nickel chloride and 4.13g of potassium chloride were added, and the mixture was stirred for 3 hours. The molar ratio of the added metal elements was V:Co:P:Mo:Ni:K = 2:0.8:1.2:0.15:0.05:0.14. (8wt% represents the percentage of vanadium relative to the carrier.)

[0108] Anatase (TiO2) support was added to the above solution and stirred until homogeneous. After impregnation at 40°C for 48 hours, the solution was filtered, washed, spray-dried, and dried to obtain the catalyst precursor. The precursor was then placed in a muffle furnace and calcined at 600°C for 12 hours. After cooling to room temperature, a vanadium-based catalyst E supported on titanium dioxide (where 8 wt% is the percentage of vanadium relative to the support) was obtained and bottled for later use.

[0109] Comparative Example 5

[0110] Preparation of 10wt% VOx / TiO2

[0111] 90g of vanadium pentoxide and 26.3g of cobalt trioxide were dissolved in 500mL of an aqueous solution containing 100g of oxalic acid. 54.8g of an 85wt% phosphoric acid solution was added, and the mixture was stirred for 2 hours. Then, 11.6g of ammonium molybdate was slowly added, and the mixture was stirred for another 2 hours. After stirring, 2.57g of nickel chloride and 4.13g of potassium chloride were added, and the mixture was stirred for 3 hours. The molar ratio of the added metal elements was V:Co:P:Mo:Ni:K = 2.5:0.8:1.2:0.15:0.05:0.14. (10wt% represents the percentage of vanadium relative to the carrier.)

[0112] Anatase (TiO2) support was added to the above solution and stirred until homogeneous. After impregnation at 40°C for 48 hours, the solution was filtered, washed, spray-dried, and dried to obtain the catalyst precursor. The precursor was then placed in a muffle furnace and calcined at 600°C for 12 hours. After cooling to room temperature, vanadium-based catalyst E supported on titanium dioxide (where 10 wt% is the percentage of vanadium relative to the support) was obtained and bottled for later use.

[0113] As can be seen from the above examples and comparative examples, the multiphase composite metal catalyst used in this invention has a simple metal composition, good fluidization, strong water resistance, wear resistance, and strong cycle stability, and has great industrial application value.

[0114] The one-step ammonia oxidation method for cyclohexane oxide described in this invention has advantages such as novel and reliable process, low cost, low pollution, recoverable catalyst, high product quality, and high yield, making it a key focus of adiponitrile production process development in my country. The yield of adiponitrile can reach 84.8%, the route is simple, green and pollution-free, and has great potential for industrial-scale production.

Claims

1. A method for selective ammoxidation of cyclohexane oxide to synthesize adiponitrile, characterized in that: Using cyclohexane oxide as a raw material, acetonitrile as a solvent, and in an atmosphere of oxygen and ammonia, adiponitrile was synthesized by selective ammoxidation of cyclohexane oxide under the action of a multiphase metal vanadium-based catalyst. The multiphase vanadium-based catalyst is a multi-component vanadium-based catalyst, wherein the active elements include vanadium (V), cobalt (Co), phosphorus (P), and molybdenum (Mo). The molar ratio of vanadium, cobalt, molybdenum, and phosphorus is 1:(0.2~1.2):(0.05~0.25):(0.3~2.0). Multi-component multiphase vanadium-based catalysts also include one or more auxiliary metal elements M or alkali metal elements N; The auxiliary metal element M is selected from one or two of manganese (Mn) and nickel (Ni); The alkali metal element N is K; The molar ratio of vanadium, auxiliary metal element M, and alkali metal element N is 1:(0.01~0.2):(0.02~0.35). The active element and auxiliary metal M exist in the catalyst in the form of oxides, while the alkali metal N exists in the catalyst in the form of a complex cation.

2. The method according to claim 1, characterized in that: The molar ratio of vanadium, cobalt, molybdenum, and phosphorus is 1:(0.4~1.0):(0.1~0.23):(0.5~1.6). The molar ratio of vanadium, auxiliary metal element M, and alkali metal element N is 1:(0.01~0.15):(0.04~0.25).

3. The method according to claim 1, characterized in that: The catalyst is 2~50 wt% Co 0.8 VP 1.2 Mo 0.15 Ni 0.05 K 0.14 O 2.52 / TiO2, its preparation method is as follows: 36 g of vanadium pentoxide and 26.3 g of cobalt trioxide were dissolved in 500 mL of an aqueous solution containing 100 g of oxalic acid. 54.8 g of 85 wt% phosphoric acid solution was added, and the mixture was stirred for 2 hours. Then, 11.6 g of ammonium molybdate was slowly added, and the mixture was stirred for 2 hours. After stirring was completed, 2.57 g of nickel chloride and 4.13 g of potassium chloride were added, and the mixture was stirred for 3 hours. The molar ratio of the added metal elements was V:Co:P:Mo:Ni:K = 1:0.8:1.2:0.15:0.05:0.14, where wt% is the percentage content of vanadium relative to the carrier. Anatase TiO2 support was added to the above solution and stirred evenly. After impregnation at 40-60℃ for 48 hours, the solution was filtered, washed, sprayed, and dried to obtain the catalyst precursor. The precursor was then placed in a muffle furnace and heated to 500-800℃ for 6-12 hours. After cooling to room temperature, vanadium-based catalyst E supported on titanium dioxide was obtained and bottled for later use. The wt% represents the percentage content of vanadium relative to the support.

4. The method according to claim 1, characterized in that: The catalyst is a supported catalyst, and the catalyst support is selected from one or more of TiO2, CeO2, ZrO2, Nb2O5, Ta2O5, MgO, Al2O3, SiO2, hydroxyapatite, and hydrotalcite. The mass loading of metallic vanadium relative to the support is 2wt%-50wt%.

5. The method according to claim 1, characterized in that: The multiphase vanadium-based catalyst is composed of Co. a V b P c Mo d MNOx / TiO2, whose active elements include vanadium (V), cobalt (Co), phosphorus (P), and molybdenum (Mo); M is one or two of the auxiliary metal elements Mn or Ni, and N is the alkali metal K; The value of a ranges from 0.2 to 1.2; The value of b ranges from 0.8 to 1.5; The value of c ranges from 0.1 to 2.0; The value of d ranges from 0.07 to 0.35; Where a, b, c, or d refer to the molar ratio; x represents the proportion of oxygen atoms required to satisfy the oxidation state of the metal; The oxidation states of the metals are as follows: The oxidation state of cobalt (Co) is one or more of +2 or +3; Vanadium V has one or more oxidation states of +2, +3, +4 or +5; The oxidation state of molybdenum (Mo) is one or more of +4 or +6; The oxidation states of manganese (Mn) are one or more of the following: +2, +3, +4, +5, +6, or +7. Nickel (Ni) has one or more oxidation states of +1, +2, +3, or +4.

6. The method according to any one of claims 1-5, characterized in that: The catalyst is prepared by impregnating a support with a corresponding metal salt solution, and the specific steps are as follows: 1) Disperse or dissolve the required amount of carrier precursor and corresponding metal salt precursor in an acidic solution with a mass concentration of 10-30%, stir evenly, and age at 40-80℃ for 12-48 h to obtain solution A; 2) Dissolve the vanadium precursor in oxalic acid solution and stir at room temperature for 1-5 h to obtain solution B; 3) Under aging temperature and stirring, solution B is added to solution A to obtain the catalyst precursor, which is then sprayed and dried; and calcined at high temperature in an oxygen atmosphere at 300~800℃ for 2~12 h to obtain the multi-component multiphase vanadium-based catalyst product. Among them, the vanadium source is a vanadium compound; The cobalt source is a cobalt compound; The molybdenum source is a molybdenum compound; The phosphorus source is a phosphorus compound; The molar ratio of the vanadium source, cobalt source, molybdenum source, and phosphorus source is 1:(0.2~1.2):(0.05~0.25):(0.3~2.0), and the molar amount of each metal raw material is calculated based on the molar amount of the element contained in its metal.

7. The method according to claim 6, characterized in that: The auxiliary metal element source is one or two salts or oxides containing one or two of the elements nickel (Ni) and manganese (Mn). The alkali metal source is a soluble alkali metal salt, which is one or more of alkali metal hydrochloride, alkali metal sulfate, or alkali metal nitrate; the molar ratio of the vanadium source, auxiliary metal source, and alkali metal source is 1:(0.01~0.2):(0.02~0.35), and the molar amount of each metal raw material is calculated based on the molar amount of the metal component elements contained therein.

8. The method according to claim 7, characterized in that: The auxiliary metal element source is one or more of nickel chloride, manganese chloride, and manganese oxide.

9. The reaction process for the selective ammoxidation of cyclohexane oxide to adiponitrile according to claim 1 is as follows: 1 mmol of cyclohexane oxide, 20-80 mg of catalyst, and 1-5 mL of reaction solvent were added to a sealed high-pressure reactor. Then, 0.5 MPa of O2 and 0.5 MPa of NH3 were added, respectively. The reactor was placed in an oil bath at 60-120 °C and stirred for 4-24 h to obtain the target product.

10. The method according to claim 9, characterized in that: The reaction solvent is any one or more of toluene, acetonitrile, tert-amyl alcohol, 1,2-dichloroethane, dimethyl sulfoxide (DMSO), N,N-dimethylformamide (DMF), n-heptane, tetrahydrofuran, and water.

11. The method according to claim 9, characterized in that: The molar ratio of V content to substrate in the catalyst ranges from 1 to 10 mol.

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