Nitrogen-doped carbon-loaded iron catalyst and application thereof in catalytic synthesis of aromatic nitrile

Abstract

The invention discloses a nitrogen-doped carbon-loaded iron catalyst and an application thereof in catalytic synthesis of aromatic nitrile, the nitrogen-doped carbon-loaded iron catalyst is used as the catalyst, aromatic alcohol and ammonia water are used as raw materials under a solvent-free condition, and the aromatic nitrile is obtained through ammoxidation reaction in an oxygen or air atmosphere. Compared with a traditional method, the nitrogen-doped carbon-loaded iron catalyst provided by the invention is subjected to ammoxidation under the condition of no solvent, so that the use of an organic solvent is avoided, the environmental pollution caused by the volatilization of the organic solvent is avoided, and the reaction energy consumption and the separation energy consumption caused by the solvent are reduced.

Description

Technical Field

[0001] The invention belongs to the technical field of catalysts and their applications, and particularly relates to a nitrogen-doped carbon-supported iron catalyst and its application in catalytic synthesis of aromatic nitrile. Background Art

[0002] Aromatic nitriles are an important class of fine chemicals, which are widely used in the fields of medicine, agricultural chemicals, fuels, fragrances, synthetic fibers, synthetic rubber and plastics. For example, benzonitrile derivatives can be used in the production of drugs (such as Febuxostat for the treatment of gouty arthritis, Etravirine for the treatment of AIDS, Milrinone for the treatment of heart failure), herbicides (Dichlorvos, Bromitriptyline, Iobenzonitrile), fungicides (Chlorothalonil, Myclobutanil), etc.

[0003] Traditional aromatic nitrile synthesis is mostly based on reactions with hydrocyanic acid or metal cyanide as cyanide sources, such as Sandmeier reaction, Rosenmund-von Braun reaction and cyanation of halogenated aromatics. The environmental disasters in Bhopal in 1984 and Baia Mare in Romania in 2000 were both related to cyanide-based nitrile synthesis. Therefore, in the past few decades until today, academia and industry have been vigorously exploring various greener and cyanide-free new methods for the synthesis of functionalized nitriles. Such as toluene ammoxidation, amide dehydration, amine oxidation, CO2 / NH3 ammoxidation and alcohol oxidative cyanation.

[0004] At present, the catalysts used for the ammoxidation of aromatic alcohols to synthesize aromatic nitriles mainly include manganese dioxide-supported ruthenium single-atom catalysts, manganese dioxide-supported cobalt oxide catalysts, etc. However, the above-mentioned catalytic systems all use organic reagents as solvents for the reaction, which not only causes a certain degree of cost increase and separation difficulties, but also causes the generation of by-products due to the change in the ratio of the reaction solution. Therefore, for the purpose of industrial application, there is a strong demand for the development of simple, highly active, highly selective, and solvent-free methods for synthesizing aromatic nitriles using aromatic alcohols as raw materials. Summary of the invention

[0005] In view of the deficiencies in the prior art, the present invention provides a nitrogen-doped carbon-supported iron catalyst and a preparation method thereof, and application of the catalyst in solvent-free ammoxidation of aromatic alcohols to synthesize aromatic nitriles.

[0006] To achieve the above object, the present invention provides the following technical solutions:

[0007] The invention provides a nitrogen-doped carbon-supported iron catalyst and a preparation method thereof, and application of the catalyst in solvent-free ammoxidation of aromatic alcohols to synthesize aromatic nitriles.

[0008] The invention provides a nitrogen-doped carbon-supported iron catalyst, comprising a nitrogen-doped carbon support and iron supported on the nitrogen-doped carbon support.

[0009] Preferably, the mass of the iron is 0.01 to 20% of the mass of the nitrogen-doped carbon-supported iron catalyst, preferably 0.01 to 10%, and more preferably 0.1 to 10%.

[0010] Preferably, the mass of the nitrogen is 1 to 20%, preferably 1 to 15%, of the nitrogen-doped carbon-supported iron catalyst.

[0011] Preferably, the mass of the carbon is 70-99% of the nitrogen-doped carbon-supported iron catalyst; preferably 70-90%.

[0012] Preferably, the specific surface area of ​​the nitrogen-doped carbon-supported iron catalyst is 300 to 1200 m 2 / g, preferably 300 to 1000 m 2 / g, more preferably 300 to 800 m 2 / g.

[0013] The present invention also provides a method for preparing the nitrogen-doped carbon-supported iron catalyst described in the above technical solution, comprising the following steps:

[0014] A soluble iron salt, a nitrogen-containing organic ligand, and a template agent are mixed and dried to obtain a catalyst precursor;

[0015] The metal salt is one or more of ferric nitrate, ferric chloride, ferric sulfate, ferrous nitrate, ferrous chloride, ferrous sulfate, ferrous acetate, etc.;

[0016] The nitrogen-containing organic ligand is one or more of urea, cyanamide, dicyandiamide, melamine, 2-methylimidazole, guanidine hydrochloride, and o-phenanthroline;

[0017] The template agent is one or more of nano magnesium oxide, nano calcium oxide, nano magnesium hydroxide, and nano calcium hydroxide;

[0018] The catalyst precursor is thermally cracked in an inert atmosphere, and then washed with an acid solution of a certain concentration to remove iron metal, iron oxide and template agent to obtain the nitrogen-doped carbon-supported iron catalyst;

[0019] The inert atmosphere is nitrogen or argon or a mixture of the two;

[0020] The thermal cracking temperature is 500-1100°C, preferably 600-1000°C, more preferably 600-900°C;

[0021] The heating rate of heating to the thermal cracking temperature is 0.5-30°C / min, preferably 0.5-20°C / min, more preferably 1-10°C / min;

[0022] The thermal cracking time is 0.5 to 12 hours, preferably 2 to 10 hours, and more preferably 3 to 6 hours.

[0023] The present invention also provides a method for catalyzing the ammoxidation of aromatic alcohols to synthesize aromatic nitriles, the specific steps of which are:

[0024] Under solvent-free conditions, in an oxygen or air atmosphere, the nitrogen-doped carbon-supported iron catalyst described in the above technical solution or the supported catalyst prepared by the above method, benzyl alcohol and ammonia water are subjected to an ammoxidation reaction.

[0025] The mass percentage of the nitrogen-doped carbon-supported iron catalyst: aromatic alcohol: 25-28wt% ammonia water is: (0.05-0.5): 1: (1.25-10), preferably (0.05-0.2): 1: (1.25-5), and more preferably (0.05-0.2): 1: (1.25-3).

[0026] The pressure of the oxygen or air is 0.1-6 MPa, preferably 0.1N4 MPa, and more preferably 0.1-2 MPa.

[0027] The reaction temperature is 25-150°C, preferably 25-120°C.

[0028] The reaction time is 0.5 to 24 hours, preferably 0.5 to 12 hours.

[0029] The aromatic alcohol includes benzyl alcohol or one of Formula-1 to Formula-8:

[0030]

[0031] Beneficial effects of the present invention: The nitrogen-doped carbon-supported iron catalyst provided by the present invention comprises a nitrogen-doped carbon support and iron supported on the nitrogen-doped carbon support. In the present invention, the nitrogen-doped carbon-supported iron catalyst realizes the solvent-free ammoxidation of aromatic alcohols to synthesize aromatic nitriles, avoids the environmental pollution caused by the volatilization of organic solvents, and reduces the reaction energy consumption caused by the use of solvents. The implementation results show that when the nitrogen-doped carbon-supported iron catalyst provided by the present invention is used to catalyze the solvent-free ammoxidation of aromatic alcohols to prepare aromatic nitriles, the conversion rate of aromatic alcohols is 100%, the selection of aromatic nitriles is as high as 99%, and there is no obvious deactivation phenomenon after the catalyst is repeatedly used 10 times. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] In order to more clearly illustrate the technical solution of the embodiment of the present invention, the following is a brief introduction to the drawings required for describing the embodiment, wherein:

[0033] Figure 1 This is the XRD spectrum of the catalyst provided in Example 1 of the present invention.

[0034] Figure 2The XANES K-space spectrum of the catalyst provided in the present invention.

[0035] Figure 3 This is the GC yield spectrum of the catalyst in Example 7 used for the solvent-free ammoxidation of benzyl alcohol to prepare benzonitrile. DETAILED DESCRIPTION

[0036] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are described in detail below in conjunction with specific embodiments.

[0037] Embodiment 1:

[0038] Ferrous chloride (0.126 g) and o-phenanthroline (CAS: XXX, C 12 H8N2) was added to 50 mL of ethanol, and after stirring for 1 hour, 2.5 g of nano-magnesium oxide (average particle size: 20 nm) was added as a template, and stirring was continued for 3 hours; dried, and then heated to 700°C at a heating rate of 5°C / min under a nitrogen atmosphere for 3 hours, and then etched with 50 mL of 4 mol / L nitric acid aqueous solution for 120 min, washed and dried to obtain a nitrogen-doped carbon-supported iron catalyst, named FeNC-700.

[0039] Embodiment 2-6:

[0040] According to the same preparation method as in Example 1, only the metal salt is replaced by one of MnCl2, CoCl2, NiCl2, CuCl2 and ZnCl2, respectively, as in Examples 2-6, the metal salt and o-phenanthroline (C 12 The molar ratio of H8N2) is 1:2, and the rest of the preparation method is the same as that of Example 1. The nitrogen-doped carbon-supported metal catalysts obtained in Examples 2-6 are named MnNC-700, CoNC-700, NiNC-700, CuNC-700, and ZnNC-700, respectively.

[0041] Embodiment 7-12:

[0042] The nitrogen-doped carbon-supported metal catalysts prepared in Examples 1-6 were used for the ammoxidation of benzyl alcohol to synthesize benzonitrile.

[0043] Reaction conditions: Weigh 10 mg of the catalyst, add the catalyst, benzyl alcohol and ammonia water into the reaction vessel in a mass ratio of 0.1:1:2, seal it, fill it with 0.5 MPa of oxygen, heat it to 120°C, keep it warm and stir it for 12 hours to obtain benzonitrile.

[0044] Table 1 Study on the ammoxidation performance of benzyl alcohol over different nitrogen-doped carbon-supported metal catalysts in Examples 7-12

[0045] Example catalyst Benzyl alcohol conversion rate (%) Benzonitrile yield (%) 7 FeNC-700 100 99 8 MnNC-700 9 5 9 CoNC-700 33 29 10 NiNC-700 6 1 11 CuNC-700 7 3 12 ZnNC-700 4 4

[0046] As can be seen from Table 1, the present invention has significantly higher conversion rate of benzyl alcohol and yield of benzonitrile under the catalytic reaction of FeNC-700.

[0047] Embodiment 13-20:

[0048] Reaction conditions: Weigh 10 mg of FeNC-700 catalyst, add FeNC-700 catalyst, benzyl alcohol and ammonia water in a mass ratio of 0.1:1:2 to the reaction vessel, seal it, fill it with 5 atm oxygen, heat it to 120°C, keep it warm and stir it for 12 hours to obtain benzonitrile. After the reaction is completed, wait for the reactor to cool naturally to room temperature. 2 mL of solvent can be added during the reaction, and the solvent is one of ultrapure water, n-heptane, toluene, 1,4-epoxyhexadecane, acetonitrile, tert-amyl alcohol, tert-butanol or no solvent.

[0049] Table 2 Benzyl alcohol ammoxidation catalyzed by FeNC-700 in different solvents

[0050] Example Solvents Benzyl alcohol conversion rate (%) Benzonitrile yield (%) 13 Solvent-free 100 99 14 n-Hexane 95 75 15 Toluene 77 68 16 Dioxane 25 24 17 Acetonitrile 49 48 18 tert-Amyl alcohol 52 52 19 Tert-Butanol 63 56 20 water 98 98

[0051] As shown in Table 2, in the present invention, under the catalytic reaction of FeNC-700, the highest conversion rate of benzyl alcohol and yield of benzonitrile are obtained under the solvent-free condition.

[0052] Embodiment 21-26:

[0053] Reaction conditions: Add the catalyst FeNC-700, benzyl alcohol and ammonia water in a mass ratio of 0.1:1:2 into the reaction vessel in sequence, seal it, fill it with 5atm oxygen, heat it to 30-160°C, keep it warm and stir it for 12h to obtain benzonitrile. After the reaction is completed, wait for the reactor to cool naturally to room temperature.

[0054] Table 3 Benzyl alcohol ammoxidation catalyzed by FeNC-700 at different reaction temperatures

[0055]

[0056]

[0057] As shown in Table 3, under the catalytic reaction of the Fe-based catalyst (FeNC-700) in the present invention, the highest conversion rate of benzyl alcohol and yield of benzonitrile were achieved at a reaction temperature of 120°C.

[0058] Embodiment 27-36:

[0059] Reaction conditions: Add FeNC-700 catalyst, benzyl alcohol and ammonia water in a mass ratio of 0.1:1:2 to the reaction vessel, seal it, fill it with 5atm oxygen, heat it to 120°C, keep it warm and stir it for 12 hours to obtain benzonitrile. After the reaction is completed, wait for the reactor to cool naturally to room temperature. After the reaction is completed, the separated catalyst is repeatedly washed and dried with ethanol and ethyl acetate for the next cycle of catalysis.

[0060] Table 4 Study on the recycling of FeNC-700 in the synthesis of benzonitrile by ammoxidation of benzyl alcohol

[0061] Example Number of applications Benzyl alcohol conversion rate (%) Benzonitrile yield (%) 27 1 97 97 28 2 95 95 29 3 93 93 30 4 96 96 31 5 95 95 32 6 97 97 33 7 95 95 34 8 96 96 35 9 95 95 36 10 94 94

[0062] As shown in Table 4, the Fe-based catalyst (FeNC-700) provided by the invention still has no obvious deactivation after repeated cycles for 10 times, and the conversion rate of benzyl alcohol and the yield of benzonitrile in the 10th reaction can reach 94%.

[0063] Embodiment 37-56:

[0064] Reaction conditions: Add FeNC-700 catalyst, aromatic alcohol and ammonia water in a mass ratio of 0.1:1:2 into the reaction vessel, seal it, fill it with 5atm oxygen, heat it to 120℃, keep it warm and stir it for 12h to obtain the corresponding substituted aromatic nitrile. After the reaction is completed, wait for the reactor to cool naturally to room temperature.

[0065] Table 5 Universality study of FeNC-700 catalyst

[0066]

[0067]

[0068]

[0069] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.

[0070] Embodiment 57-58:

[0071] According to the same preparation method as in Example 1, only the o-phenanthroline ligand was replaced by one of melamine and 2-methylimidazole, respectively, as Examples 57-58, the molar ratio of ferrous chloride to the nitrogen-containing organic ligand was 1:2, and the rest of the preparation method was the same as in Example 1. The nitrogen-doped carbon-supported iron catalysts obtained in Examples 57-58 were named FeNC-700-MA and FeNC-700-2Mm, respectively.

[0072] Examples 59-61:

[0073] The nitrogen-doped carbon-supported iron catalyst prepared in Examples 1 and 57-58 was used for the ammoxidation of benzyl alcohol to synthesize benzonitrile.

[0074] Reaction conditions: 10 mg of catalyst, benzyl alcohol and aqueous ammonia were added into a reaction vessel in a mass ratio of 0.1:1:2, sealed, filled with 5 atm of oxygen, heated to 120°C, stirred and reacted for 12 hours to obtain benzonitrile.

[0075] Table 6 Study on the ammoxidation performance of benzyl alcohol over different nitrogen-doped carbon-supported iron catalysts in Examples 59-61

[0076]

[0077]

[0078] Examples 62-67:

[0079] According to the same preparation method as in Example 1, only the metal iron salt FeCl2 is replaced by one of Fe(NO3)3, FeCl3, Fe2(S04)3, Fe(NO3)2, FeSO4 and Fe(OAc)2, respectively, as Examples 62-67, the metal iron salt and o-phenanthroline (C 12 The molar ratio of H8N2) is 1:2, and the rest of the preparation method is the same as that of Example 1. The nitrogen-doped carbon-negative iron-supported catalysts obtained in Examples 62-67 are respectively named Fe 3+ NC-700-NO3 2- , Fe 3+ NC-700-Cl - , Fe 3+ NC-700-SO4 2- , Fe 2+ NC-700-NO3 2- , Fe 2+ NC-700-SO4 2- , Fe 2+ NC-700-OAc - .

[0080] Examples 68-74:

[0081] The nitrogen-doped carbon-supported iron catalysts prepared in Examples 1 and 62-67 were used for the ammoxidation of benzyl alcohol to synthesize benzonitrile.

[0082] Reaction conditions: 10 mg of catalyst, benzyl alcohol and aqueous ammonia were added into a reaction vessel in a mass ratio of 0.1:1:2, sealed, filled with 5 atm of oxygen, heated to 120°C, stirred and reacted for 12 hours to obtain benzonitrile.

[0083] Table 7 Study on the ammoxidation performance of benzyl alcohol over different iron catalysts supported by nitrogen-doped carbon in Examples 68-74

[0084] Example catalyst Benzyl alcohol conversion rate (%) Benzonitrile yield (%) 68 FeNC-700 100 99 69 <h2 style=";text-align:left;direction:ltr"><![CDATA[Fe <h2 style=";text-align:left;direction:ltr"> 3+ <h2 style=";text-align:left;direction:ltr"> NC-700-NO3<h2 style=";text-align:left;direction:ltr"> 2- <h2 style=";text-align:left;direction:ltr"> ]]><h2 style=";text-align:left;direction:ltr"> 31 30 70 <![CDATA[Fe 3+ NC-700-Cl - ]]> 90 88 71 <![CDATA[Fe 3+ NC-700-SO4 2- ]]> 22 22 72 <h2 style=";text-align:left;direction:ltr"><![CDATA[Fe <h2 style=";text-align:left;direction:ltr"> 2+ <h2 style=";text-align:left;direction:ltr"> NC-700-NO3<h2 style=";text-align:left;direction:ltr"> 2- <h2 style=";text-align:left;direction:ltr"> ]]><h2 style=";text-align:left;direction:ltr"> 46 43 73 <![CDATA[Fe 2+ NC-700-SO4 2- ]]> 39 38 74 <![CDATA[Fe 2+ NC-700-OAc - ]]> 63 61

Claims

1. A nitrogen-doped carbon-supported iron catalyst, characterized in that: The invention comprises a nitrogen-doped carbon carrier and iron loaded on the carrier; the mass of the iron is 0.01-20% of the nitrogen-doped carbon-loaded iron catalyst; the nitrogen-doped carbon-loaded iron catalyst is obtained by mixing a soluble iron salt, a nitrogen-containing organic ligand and a template agent, drying the mixture and thermally decomposing the mixture; the nitrogen-containing organic ligand is one of urea, cyanamide, dicyandiamide, melamine, 2-methylimidazole, guanidine hydrochloride and o-phenanthroline.

2. The nitrogen-doped carbon-supported iron catalyst according to claim 1, characterized in that: The mass of the nitrogen is 1-20% of the nitrogen-doped carbon-supported iron catalyst; the mass of the carbon is 70-99% of the nitrogen-doped carbon-supported iron catalyst.

3. The nitrogen-doped carbon-supported iron catalyst according to claim 1 or 2, characterized in that: The specific surface area of ​​the nitrogen-doped carbon-supported iron catalyst is 300 to 1200 m 2 / g.

4. The nitrogen-doped carbon-supported iron catalyst according to claim 1 or 2, characterized in that: The soluble iron salt includes one or more of ferric nitrate, ferric chloride, ferric sulfate, ferrous nitrate, ferrous chloride, ferrous sulfate, and ferrous acetate; the template agent includes one or more of nano magnesium oxide, nano calcium oxide, nano magnesium hydroxide, and nano calcium hydroxide.

5. The nitrogen-doped carbon-supported iron catalyst according to claim 1 or 2, characterized in that: The pyrolysis temperature is 500-1100° C., the pyrolysis temperature is 0.5-30° C. / min, and the pyrolysis time is 0.5-12h.

6. Use of the nitrogen-doped carbon-supported iron catalyst according to claim 1 to catalyze the ammoxidation of aromatic alcohols to synthesize aromatic nitriles.

7. The use according to claim 6, characterized in that: The nitrogen-doped carbon-supported iron catalyst, aromatic alcohol and ammonia water are added into a reaction kettle, and oxygen or air is introduced to carry out an ammoxidation reaction to obtain aromatic nitrile.

8. The use according to claim 7, characterized in that: The mass ratio of nitrogen-doped carbon-supported iron catalyst: aromatic alcohol: ammonia water is (0.05-0.5):1:(1.25-10); the temperature of the ammoxidation reaction is 25-150° C., and the reaction time is 0.5-24 h.

9. The use according to claim 7, characterized in that: The pressure of oxygen or air is 0.1 to 6 MPa.

10. The use according to any one of claims 6 to 9, characterized in that: The aromatic alcohol includes benzyl alcohol or one of Formula-1 to Formula-8:

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