CN105618083A - Application of adjuvant-containing catalyst in selective hydrogenation reaction of aromatic nitro compound - Google Patents

Abstract

The application of a promoter-containing catalyst in the selective hydrogenation reaction of aromatic nitro compounds, the active component of the catalyst is one or two or more of Group VIII or Group IB metals, the carrier is iron oxide, and the content of the active component is 0.01%-50%. The addition of the promoter alkali metal can significantly improve the selectivity of the catalyst for the hydrogenation of aromatic nitro compounds. Compared with the existing industrial synthesis route of selective hydrogenation of aromatic nitro compounds, the reaction process provided by the present invention has obvious advantages such as green and environment-friendly, simple operation and cost saving.

Description

Application of Promoter-Containing Catalysts in Selective Hydrogenation of Aromatic Nitro Compounds

technical field

The invention relates to the application of a promoter-containing catalyst in the selective hydrogenation reaction of aromatic nitro compounds.

Background technique

The selective hydrogenation of aromatic nitro compounds to obtain corresponding functionalized anilines has important applications in many fields, such as pesticides, medicines, dyes and high molecular polymers. For the hydrogenation of simple aromatic nitro compounds, there are mature technologies in industry, but for the substituents that are reducible groups, such as carbon-carbon double bonds, carbon-carbon triple bonds, carbon-oxygen double bonds, carbon-nitrogen In the presence of triple bonds, etc., it is still a challenging subject to selectively reduce the nitro group while keeping the double bond from hydrogenation. In industry, for the selective hydrogenation of aromatic nitro compounds containing reducible groups, metered reducing agents are generally used, such as Na ₂ S ₂ O ₄ , adding Fe, Zn, Sn, etc. to ammonia water as reducing agents , but such a reducing agent will produce at least one mole of waste while obtaining one mole of the target product. In order to overcome this shortcoming, the researchers used hydrogen as the reducing agent and added PbO or H ₃ PO ₂ to the On supported Pt catalysts, although the activity is reduced, the selectivity to the target product is improved, but such catalysts will produce benzene annephrine intermediates, which may be explosive hazards even at very low levels. The researchers found that adding iron salts or alum salts to the catalytic system can convert this intermediate product into the target product, but a large amount of transition metal salts remain in the solution after the reaction, and the subsequent treatment process is complicated, which is not very economical and environmentally friendly. . Therefore, it is urgent to find a heterogeneous catalyst with high activity and high selectivity for this kind of reaction.

Many patents and documents have introduced the selective hydrogenation of aromatic nitro compounds supported gold and platinum catalysts, with different supports and preparation methods, and their activities are not the same.

Document 1 (WO2007116111-A1) found that Au/TiO ₂ and Au/Fe ₂ O ₃ catalysts showed good selectivity in the selective hydrogenation of aromatic nitro compounds. The author found that the reason for the high selectivity was that aromatic nitro compounds The nitro group of the base compound will be preferentially adsorbed on the interface of Au and _TiO2 supports, so that the nitro group will be preferentially reduced, showing high selectivity.

Document 2 (J.Phys.Chem.C2009, 113, 17803–17810) prepared Au/Al ₂ O ₃ catalysts by sol deposition method, which also showed good selectivity for this type of selective hydrogenation. And the activity is higher than Au/TiO ₂ . However, the disadvantage of the Au catalyst is that it has poor dissociation ability to hydrogen, so the reaction conditions are relatively harsh. The reaction temperature is above 100°C and the pressure is above 1Mp.

Document 3 (Adv.Synth.Catal.2011, 353, 1260–1264) prepared a porous ionic copolymer-supported Pt catalyst by a one-pot method. The loading of Pt was 4.9wt%. 2-4nm. At room temperature, it exhibits high activity and selectivity for substituents R=F, Cl, Br, I, CHO, CN, NH ₂ , CH ₃ CO, OH, etc., but for substituents -C=C- , showing very low selectivity.

Document 4 (Journal of Catalysis 265 (2009) 19–25) uses Au catalysts with high selectivity for aromatic nitro compounds, and Pt is a metal with good hydrogenation activity, combining the characteristics of the two, in this type of reaction The phenotype showed a good synergistic effect. The author incorporated 0.01% Pt in the Au/TiO ₂ catalyst, and the conversion rate of 94.5% and the selectivity of 93.4% could be obtained under the reaction conditions of 85 ° C and 8 bar P _H2 .

Document 5 (WO2009071727) prepared a Pt/TiO ₂ catalyst by impregnation method. Under the reaction conditions of 40 ° C and 3 bar P _H2 , in the selective hydrogenation reaction of 3-nitrostyrene, when the loading amount is 0.2% , need reaction 7h to be able to obtain the yield of 92%, the selectivity is 93.1%.

Contents of the invention

The purpose of the present invention is to change the electronic properties of the catalyst through the addition of alkali metal promoters, thereby significantly improving the selectivity of the catalyst for the hydrogenation of aromatic nitro compounds, the reaction conditions are mild, the catalyst is stable, and it is magnetic and easy to recycle Easy to use and operate. To achieve the above object, the technical solution provided by the invention is:

The application of a promoter-containing catalyst in the selective hydrogenation reaction of aromatic nitro compounds is characterized in that: the active component of the catalyst is one or more than two metals of Group VIII or Group IB, and the alkali metal is used as a promoter , the carrier is iron oxide, the active component and the auxiliary agent are jointly carried on the carrier, the mass content of the active component in the catalyst is 0.5%-50%, and the mass content of the auxiliary agent in the catalyst is 0.01%-40%.

The active component is one or more of Pt, Pd and Ni, and the content of the active component is 0.01-20 wt%.

The alkali metal is one or more of lithium, sodium and potassium, and the mass content of the additive in the catalyst is 0.01-20wt%.

The first preparation process is as follows:

1) The soluble precursor of the metal active component and ferric nitrate are formulated into a mixed aqueous solution, which is recorded as solution A, and the aqueous solution of ammonium carbonate with a concentration of 1×10 ^-4 -1mol/L is recorded as solution B; the soluble precursor of the metal active component in solution A is Body concentration 0.1-50mg/ml, ferric nitrate concentration 0.1-1mol/L;

2) Solution B is stirred at 50°C-100°C, and solution A is added dropwise to solution B; the volume ratio of solution A to solution B is 0.001-1000;

3) After the dropwise addition, continue to stir for 1-10 hours at a temperature of 50°C-100°C, and then let stand for 1-10 hours;

4) After standing, separate the solid, filter the solid with deionized water, and dry the solid;

5) Grinding the dried solid catalyst and impregnating the alkali metal solution;

6) Dry the catalyst impregnated with the alkali metal solution, the drying temperature is 25-120°C, and the drying time is 1-24 hours; after drying, the solid is roasted, the roasting temperature is 200°C-800°C, and the roasting time is 1-24 hours ;

The alkali metal solution is one or more of alkali metal carbonates, nitrates, chlorides, sodium hydroxide, potassium hydroxide, lithium hydroxide, etc.;

The concentration of the alkali metal solution is 0.001mol/L-10mol/L;

7) The catalyst is subjected to reduction treatment before being used in the reaction. The reduction atmosphere is hydrogen or a mixture of hydrogen and inert gas with a hydrogen volume concentration greater than or equal to 10%. The reduction temperature is 50°C-800°C and the reduction time is 10-120min.

The second preparation process is as follows,

1) The soluble precursor of the metal active component and ferric nitrate is formulated into a mixed solution, which is recorded as solution A, and the aqueous solution of ammonium carbonate with a concentration of 1×10 ^-4 -1mol/L is recorded as solution B; the soluble precursor of the metal active component in solution A is Body concentration 0.1-50mg/ml, ferric nitrate concentration 0.1-1mol/L.

2) Solution B is stirred at 50°C-100°C, and solution A is added dropwise to solution B; the volume ratio of solution A to solution B is 0.001-1000;

3) After the dropwise addition, continue to stir for 1-10 hours at a temperature of 50°C-100°C, and then let stand for 1-10 hours;

4) After standing, separate the solid, filter the solid with deionized water, dry the solid, and roast the dried solid at 200°C-800°C for 1-24 hours;

5) Grinding the calcined solid catalyst and impregnating it with an alkali metal solution;

6) Dry the catalyst impregnated with the alkali metal solution, the drying temperature is 25-120°C, and the drying time is 1-24 hours; after drying, the solid is roasted, the roasting temperature is 200°C-800°C, and the roasting time is 1-24 hours ;

The alkali metal solution is one or more of alkali metal carbonates, nitrates, chlorides, sodium hydroxide, potassium hydroxide, lithium hydroxide, etc.;

The concentration of the alkali metal solution is 0.001mol/L-10mol/L;

7) The catalyst is subjected to reduction treatment before being used in the reaction. The reduction atmosphere is hydrogen or a mixture of hydrogen and inert gas with a hydrogen volume concentration greater than or equal to 10%. The reduction temperature is 50°C-800°C and the reduction time is 10-120min.

The reaction is carried out in a closed high-pressure reactor, the initial pressure of hydrogen in the reactor is 0.1-5Mpa at room temperature, the reaction temperature is 20-150°C, and the reaction time is not less than 10 minutes.

The reaction is carried out in a solvent, and the solvent used is one or more of ethanol, methanol, toluene, tetrahydrofuran, dodecane, and water, and the substrate concentration of the reaction solution is 0.001-10mol/L;

The reaction substrate is an aromatic nitro compound Substituent R is one of hydrogen, halogen, vinyl, ethynyl, nitrile, aldehyde, phenolic hydroxyl, carbonyl, methyl, isopropyl, methoxy, and the number of substituents R is 1-5 a; or the reaction substrate is One of them, the substituent R is one of hydrogen, halogen, vinyl, ethynyl, nitrile, aldehyde, phenolic hydroxyl, carbonyl, methyl, isopropyl, methoxy, each of the substituent R The number is 1-4.

The molar ratio of the catalyst active component to the reaction substrate is between 1×10 ^-4 and 1.

The preferred reaction temperature is 20-80°C, the preferred initial pressure of hydrogen in the reactor at room temperature is 0.1-1.5Mpa, and the preferred reaction time is 0.5h-3h.

The catalyst can be recycled for more than 2 times, its conversion rate and selectivity do not decrease significantly, and the catalyst is easily separated from the reaction solution.

The activity test method to the catalyst provided by the invention is as follows:

The reactor is a high-pressure reactor, and the reaction substrate and the internal standard are prepared into a reaction solution with a certain concentration. Each reaction uses a pipette to take a certain amount of the reaction solution for the reaction. The initial pressure of the hydrogen in the reactor at room temperature is 0.1- 5Mpa, the reaction temperature is 20-150°C, and the reaction time is not less than 10 minutes. After the reaction was completed and cooled to room temperature, samples were taken for gas chromatography analysis.

The present invention has following effect:

1. The selective hydrogenation of aromatic nitro compounds to obtain corresponding functionalized anilines has applications in many fields, such as agriculture, medicine, dyes and high molecular polymers. The invention provides a catalyst added with an alkali metal, which can catalyze functionalized aniline with high selectivity.

2. The present invention provides that the catalyst added with alkali metal can be recycled for more than 2 times in the reaction of selective hydrogenation of aromatic nitro compounds, and the activity does not decrease significantly.

3. The catalyst provided by the invention is easy to separate from the reaction solution after the reaction, and the operation is simple and convenient.

In a word, the present invention realizes efficient and highly selective conversion of aromatic nitro compounds to prepare functionalized aniline. Compared with the existing industrial catalyst system, the catalyst provided by the present invention is green and friendly in the process of this type of reaction, saving cost , is expected to be applied in industry.

detailed description

X is 1, 4/3 or 3/2 in following embodiment;

Embodiment 1: Get the ammonium carbonate of 3.5g in the deionized water of 60mL, and the gained solution is denoted as solution A. Take 20mL of 1M ferric nitrate solution in a beaker, add 9mL of 14.8mg _Pt /ml H ₂ PtCl ₆ solution, stir evenly, and record the obtained solution as solution B. Solution A was stirred under a water bath at 50°C, and solution B was added dropwise to solution A at a rate of 1 mL/min. After completion of the dropwise addition, stirring was continued at the same temperature for 3 hours, and then left still for 3 hours. After suction filtration with 500mL of deionized water, oven-dry at 60°C for 5h, take it out and bake in a muffle furnace at 400°C for 5h to obtain a 2.16% Pt/FeO _X catalyst.

Embodiment 2: Get 3.5g of ammonium carbonate in 60mL of deionized water, and the resulting solution is designated as solution A. Take 20mL of 1M ferric nitrate solution in a beaker, add 9mL of 14.8mg _Pt /ml H ₂ PtCl ₆ solution, stir evenly, and record the obtained solution as solution B. Solution A was stirred under a water bath at 50°C, and solution B was added dropwise to solution A at a rate of 1 mL/min. After completion of the dropwise addition, stirring was continued at the same temperature for 3 hours, and then left still for 3 hours. After suction filtration with 500mL deionized water, oven-dry at 60°C for 5h, take it out and grind it. Weigh 0.0075g of sodium nitrate and dissolve it in 0.3g of deionized water, weigh 0.4g of the ground catalyst and add it to the sodium nitrate solution, stir evenly, dry at 60°C for 5h, and then roast in a muffle furnace at 400°C for 5h to obtain 0.75% Na-Pt/FeO _X catalyst.

Embodiment 3: Get 3.5g of ammonium carbonate in 60mL of deionized water, and the resulting solution is designated as solution A. Take 20mL of 1M ferric nitrate solution in a beaker, add 9mL of 14.8mg _Pt /ml H ₂ PtCl ₆ solution, stir evenly, and record the obtained solution as solution B. Solution A was stirred under a water bath at 50°C, and solution B was added dropwise to solution A at a rate of 1 mL/min. After completion of the dropwise addition, stirring was continued at the same temperature for 3 hours, and then left still for 3 hours. After suction filtration with 500mL deionized water, oven-dry at 60°C for 5h, take it out and grind it. Weigh 0.015g of sodium nitrate and dissolve it in 0.3g of deionized water, weigh 0.4g of the ground catalyst and add it to the sodium nitrate solution, stir well, dry at 60°C for 5h, and then roast in a muffle furnace at 400°C for 5h to obtain 1.75% Na-Pt/FeO _X catalyst.

Embodiment 4: Get 3.5g of ammonium carbonate in 60mL of deionized water, and the resulting solution is designated as solution A. Take 20mL of 1M ferric nitrate solution in a beaker, add 9mL of 14.8mg _Pt /ml H ₂ PtCl ₆ solution, stir evenly, and record the obtained solution as solution B. Solution A was stirred under a water bath at 50°C, and solution B was added dropwise to solution A at a rate of 1 mL/min. After completion of the dropwise addition, stirring was continued at the same temperature for 3 hours, and then left still for 3 hours. After suction filtration with 500mL deionized water, oven-dry at 60°C for 5h, take it out and grind it. Weigh 0.03g of sodium nitrate and dissolve it in 0.3g of deionized water, weigh 0.4g of the ground catalyst and add it to the sodium nitrate solution, stir evenly, dry at 60°C for 5h, and then roast in a muffle furnace at 400°C for 5h to obtain 3.0% Na-Pt/FeO _X catalyst.

Embodiment 5: Take 3.5g of ammonium carbonate in 60mL of deionized water, and the resulting solution is designated as solution A. Take 20mL of 1M ferric nitrate solution in a beaker, add 9mL of 14.8mg _Pt /ml H ₂ PtCl ₆ solution, stir evenly, and record the obtained solution as solution B. Solution A was stirred under a water bath at 50°C, and solution B was added dropwise to solution A at a rate of 1 mL/min. After completion of the dropwise addition, stirring was continued at the same temperature for 3 hours, and then left still for 3 hours. After suction filtration with 500mL deionized water, oven-dry at 60°C for 5h, take it out and grind it. Weigh 0.05g of sodium nitrate and dissolve it in 0.3g of deionized water, weigh 0.4g of the ground catalyst and add it to the sodium nitrate solution, stir evenly, dry at 60°C for 5h, and then roast in a muffle furnace at 400°C for 5h to obtain 5.0% Na-Pt/FeO _X catalyst.

Application example:

The catalysts were all reduced with 10% H ₂ /He before use. The reduction condition was 10°C/min to 250°C. After reduction for 30 minutes, purging with He for 30 minutes, quickly took out and weighed 0.1g and poured it into the reaction tube. Add 5ml of 0.1M 3-nitrostyrene reaction solution (toluene as solvent, ortho-xylene as internal standard) into the pipette, and the reaction conditions are 3 bar P _H2 , 40°C.

The specific experimental results are as follows:

Table 1 The results of selective hydrogenation of 3-nitrostyrene with different alkali metal additions

It can be seen from the table that with the increase of the promoter alkali metal, the selectivity to the target product is obviously improved. When the additive amount is 3%, the selectivity of the catalyst to the target product can reach 96.7%.

Table 2 The results of selective hydrogenation of 3-nitrostyrene by adding different alkali metals

It can be seen from the data in the table that the addition of different alkali metals can significantly improve the selectivity of the target product.

Table 3 Cyclic Stability Experiment of Catalysts After Adding Additives

It can be seen from Table 3 that the catalyst after adding alkali metal showed good stability, and its activity and selectivity did not decrease after four cycles.

Table 4 The results of selective hydrogenation of 2.16%Pt/FeO _x -3.0%Na in different reaction substrates

It can be seen from the data in the table that the catalyst also has high selectivity for other substrates.

Claims (10)

1. The application of promoter-containing catalyst in the selective hydrogenation reaction of aromatic nitro compounds is characterized in that: the active component of the catalyst is one or more than two kinds of metals in Group VIII or Group IB, with alkali metal as The auxiliary agent, the carrier is iron oxide, the active component and the auxiliary agent are jointly loaded on the carrier, the mass content of the active component in the catalyst is 0.5%-50%, and the mass content of the auxiliary agent in the catalyst is 0.01%-40%, The balance is carrier. 2. The application according to claim 1, characterized in that: the active component is one or more of Pt, Pd and Ni, and the content of the active component is 0.01-20wt%. 3. The application according to claim 1, characterized in that: the alkali metal is one or more of lithium, sodium and potassium, and the mass content of the additive in the catalyst is 0.01-20wt%. 4. as the arbitrary described application of claim 1-3, it is characterized in that: its preparation process is as follows, 1) The soluble precursor of the metal active component and ferric nitrate are formulated into a mixed aqueous solution, which is recorded as solution A, and the aqueous solution of ammonium carbonate with a concentration of 1×10 ^-4 -1mol/L is recorded as solution B; the soluble precursor of the metal active component in solution A is Body concentration 0.1-50mg/ml, ferric nitrate concentration 0.1-1mol/L; 2) Solution B is stirred at 50°C-100°C, and solution A is added dropwise to solution B; the volume ratio of solution A to solution B is 0.001-1000; 3) After the dropwise addition, continue to stir for 1-10 hours at a temperature of 50°C-100°C, and then let stand for 1-10 hours; 4) After standing, separate the solid, filter the solid with deionized water, and dry the solid; 5) Grinding the dried solid catalyst and impregnating the alkali metal solution; 6) Dry the catalyst impregnated with the alkali metal solution, the drying temperature is 25-120°C, and the drying time is 1-24 hours; after drying, the solid is roasted, the roasting temperature is 200°C-800°C, and the roasting time is 1-24 hours ; Described alkali metal solution is carbonate, nitrate, chloride salt and sodium hydroxide, hydroxide of alkali metal Potassium, lithium hydroxide, etc. one or two or more; The concentration of the alkali metal solution is 0.001mol/L-10mol/L; 7) The catalyst is subjected to reduction treatment before being used in the reaction. The reduction atmosphere is hydrogen or a mixture of hydrogen and inert gas with a hydrogen volume concentration greater than or equal to 10%. The reduction temperature is 50°C-800°C and the reduction time is 10-120min. 5. as the arbitrary described application of claim 1-3, it is characterized in that: its preparation process is as follows, 1) The soluble precursor of the metal active component and ferric nitrate is formulated into a mixed solution, which is recorded as solution A, and the aqueous solution of ammonium carbonate with a concentration of 1×10 ^-4 -1mol/L is recorded as solution B; the soluble precursor of the metal active component in solution A is Body concentration 0.1-50mg/ml, ferric nitrate concentration 0.1-1mol/L. 2) Solution B is stirred at 50°C-100°C, and solution A is added dropwise to solution B; the volume ratio of solution A to solution B is 0.001-1000; 3) After the dropwise addition, continue to stir for 1-10 hours at a temperature of 50°C-100°C, and then let stand for 1-10 hours; 4) After the completion, separate the solid, filter the solid with deionized water, dry the solid, and roast the solid after drying. The roasting temperature is 200°C-800°C, and the roasting time is 1-24 hours; 5) Grinding the calcined solid catalyst and impregnating it with an alkali metal solution; 6) Dry the catalyst impregnated with the alkali metal solution, the drying temperature is 25-120°C, and the drying time is 1-24 hours; after drying, the solid is roasted, the roasting temperature is 200°C-800°C, and the roasting time is 1-24 hours ; The alkali metal solution is one or more of alkali metal carbonates, nitrates, chlorides, sodium hydroxide, potassium hydroxide, lithium hydroxide, etc.; The concentration of the alkali metal solution is 0.001mol/L-10mol/L; 7) The catalyst is subjected to reduction treatment before being used in the reaction. The reduction atmosphere is hydrogen or a mixture of hydrogen and inert gas with a hydrogen volume concentration greater than or equal to 10%. The reduction temperature is 50°C-800°C and the reduction time is 10-120min. 6. The application according to claim 1, characterized in that: The reaction is carried out in a closed high-pressure reactor, the initial pressure of hydrogen in the reactor is 0.1-5Mpa at room temperature, the reaction temperature is 20-150°C, and the reaction time is not less than 10 minutes. 7. The application according to claim 1 or 6, characterized in that: The reaction is carried out in a solvent, and the solvent used is one or more of ethanol, methanol, toluene, tetrahydrofuran, dodecane, and water, and the substrate concentration of the reaction solution is 0.001-10mol/L; The reaction substrate is an aromatic nitro compound Substituent R is one of hydrogen, halogen, vinyl, ethynyl, nitrile, aldehyde, phenolic hydroxyl, carbonyl, methyl, isopropyl, methoxy, and the number of substituents R is 1-5 a; or the reaction substrate is One of them, the substituent R is one of hydrogen, halogen, vinyl, ethynyl, nitrile, aldehyde, phenolic hydroxyl, carbonyl, methyl, isopropyl, methoxy, each of the substituent R The number is 1-4. 8. The application according to claim 1 or 6, characterized in that: The molar ratio of the catalyst active component to the reaction substrate is between 1×10 ^-4 and 1. 9. The application according to claim 1 or 6, characterized in that: The preferred reaction temperature is 20-80°C, the preferred initial pressure of hydrogen in the reactor at room temperature is 0.1-1.5Mpa, and the preferred reaction time is 0.5h-3h. 10. The application according to claim 1, characterized in that: the catalyst can be recycled for more than 2 times, its conversion rate and selectivity do not decrease significantly, and the catalyst is easily separated from the reaction solution.