CN116474794A - Preparation method and application of dual-function molded framework cobalt catalyst - Google Patents

Abstract

The invention relates to the preparation of a zirconium-based skeleton cobalt catalyst with bifunctional catalysis. The preparation method is as follows: preparing zirconia synthetic sol; smelting cobalt and aluminum alloy and crushing it into alloy powder; adding cobalt aluminum alloy powder into gel, drying, pressing and activating to obtain a zirconium-based skeleton cobalt catalyst. The characteristic of this catalyst is that it has a certain acidity compared with common Raney catalysts. When it is applied to the amination and hydrogenation of isophoronenitrile (IPN) to prepare isophoronediamine (IPDA), it can simultaneously perform imidization, hydrogenation, and inhibit the hydrolysis of the intermediate product isophoronenitrile imine, and improve the conversion rate of IPN. According to experiments, the conversion rate of IPN can reach 100%, the selectivity of IPDA is greater than 99%, and the by-products are greatly reduced.

Description

Preparation method and application of a bifunctional shaped framework cobalt catalyst

technical field

This patent relates to the preparation and application of a bifunctional skeleton Co catalyst, which can be applied to the amination and hydrogenation of 3-cyano-3,5,5-trimethylcyclohexanone (IPN) to prepare 3-aminomethyl-3,5,5-trimethylcyclohexylamine (IPDA).

Background technique

3-Aminomethyl-3,5,5-trimethylcyclohexylamine (isophorone diamine, IPDA) is mainly used in the preparation of polymer materials such as isophorone diisocyanate and polyamide, and is also used in curing agents. Such materials have good chemical resistance and thermosetting properties. IPDA is a mixture of cis/trans isomers, and IPDA with different ratios of cis/trans isomers is suitable for different fields. According to German published patent DEA421154, IPDA with cis isomer less than 60% is beneficial to reduce the maximum curing temperature of epoxy resin, while IPDA with cis isomer content higher than 70% is beneficial to increase the reaction rate of polymer resin.

U.S. published patents US3352913 and US570569 disclose a two-step process for producing IPDA, which is also the mainstream process for industrial production at present, that is, 3-cyano-3,5,5-trimethylcyclohexanone (isophoronenitrile, IPN) is reacted with excess ammonia, imidized under the action of an acidic or alkaline catalyst to obtain isophoronenitrile imine, and then reacted with hydrogen to produce isophoronediamine under the action of a Raney catalyst. The reaction of isophoronenitrile and ammonia to generate isophoronenitrile imine is a reversible reaction, and its reverse reaction is the hydrolysis reaction of Schiff base. The IPN generated will be directly hydrogenated to obtain aminoalcohol, which is also the most important by-product of this reaction.

In addition, the catalyst suitable for the hydrogenation reaction in the second step of the above-mentioned process is a skeleton cobalt catalyst. U.S. published patent US6087296 discloses a preparation method of a skeleton cobalt catalyst, specifically, direct alkali treatment and activation of Co-Al alloy powder. However, the yield of this method is low, and the strength of the catalyst is low, and it is easy to pulverize, which indirectly increases the cost. Patents CN1557918A and US6489521 disclose the preparation method of shaped skeleton cobalt catalysts. These patents use inorganic or organic binders mixed with metal powder to prepare skeleton cobalt catalysts through a series of methods, but they are not applied to IPDA reaction examples.

Contents of the invention

In view of the above-mentioned defects, the present invention provides a class of skeleton cobalt catalysts with dual functions of imidization and hydrogenation. At the same time, the strength of the catalyst is greater than that of traditional skeleton cobalt catalysts, and its lifespan is longer.

Another object of the present invention is the purposes of this catalyst, and it is used as the catalyst of IPN to prepare IPDA, can suppress the hydrolysis reaction of intermediate product isophorone nitrile imine on the one hand, have hydrogenation performance concurrently simultaneously, greatly improve the yield of IPDA.

In order to achieve the above object, the present invention provides a method for preparing a bifunctional shaped framework cobalt catalyst, the scheme is as follows:

(1) Co-Al alloy is prepared, then it is broken into alloy powder, and a certain amount of metal auxiliary agent and binder are mixed in;

(2) preparing zirconia synthetic gel;

(3) Mixing the product obtained in step (1) and step (2), drying, pressing into tablets, and activating with lye in situ to obtain a catalyst.

By "adding the Raney precursor and then in-situ activation during the preparation of the gel", the advantage of this solution is that the Raney is coupled with the acidic catalyst during the preparation process instead of the traditional loading, which strengthens the interaction between the catalysts and ensures the catalytic performance. At the same time, in-situ activation is used, which fundamentally solves the problem of the strength of the coupled catalyst, without pulverization, agglomeration, etc., and keeps its catalytic activity to the maximum extent.

In the method of the present invention, in step (1), the mass ratio of cobalt to aluminum in the cobalt-aluminum alloy is 0.5-1.5, the smelting temperature is 1600-1800°C, stirring is applied during smelting, the stirring time is 2-5min, and the stirring rate is 20-50r/min. After the stirring was completed, it was naturally cooled to room temperature to obtain an alloy block. The diameter of the particles obtained after the alloy block is crushed is between 100-400 mesh, preferably 200-300 mesh.

In the method of the present invention, in step (1), the binder used is one or more of graphite, Tianqing powder, and cellulose. The addition amount is 5-20wt%, based on the mass of alloy powder. The traditional IPDA hydrogenation catalyst is to directly activate the alloy block and apply it to the fixed bed. If the hydrogenation performance of the catalyst is improved, the degree of activation must be increased. If the degree of activation is increased, the strength of the catalyst will be directly reduced, and the strength will be reduced. The catalyst is easy to pulverize and pollute the material during the reaction.

In the method of the present invention, in step (1), the added metal additive is one or more of Ca, Mg, P, Ni, Pt, Cr, Co, Ti, Mg, B, Zn, Mo, and the addition amount is 0.1-5wt%, based on the quality of the alloy powder.

In the method of the present invention, step (2) is used to prepare zirconia synthetic gel. A certain amount of tetrabutyl zirconate, deionized water, and ruthenium acetate are mixed evenly, and the mass ratio of the three is 1:x:y, wherein x is 1-20, preferably 2-10, and y is 1-10, preferably 2-8. Sulfuric acid was then added to adjust the pH to 1-5. Stir for 5-72h to obtain zirconia synthetic gel.

In the method of the present invention, in step (3), the alloy powder and the zirconia gel are mixed in a mass ratio of 1:5-15, preferably 1:6-12, stirred evenly, and dried at 80-100°C for 6-12 hours. Then tablet. The tablet grinding tool should be a cylinder with a diameter of 1-5mm and a height of 2-6mm. A cylinder with a diameter of 2-4 mm and a height of 3-5 mm is preferred.

In the method of the present invention, in step (3), the activation method used is in-situ lye washing activation. The alkali used is one of sodium hydroxide, potassium hydroxide, sodium carbonate and ammonia water. The required lye concentration is 5-30wt%, preferably 10-25wt%. The temperature for activation is 60-90°C, preferably 70-90°C. The activation time is 1-3h, and the space velocity of the lye is controlled at 5-20h ^-1 during activation.

The high-strength dual-functional catalyst with acidic-hydrogenation performance obtained by the method is applied to the fixed-bed IPN one-step method for preparing IPDA. During the evaluation, a single-tube reactor was used, and the catalyst was loaded with 50mL. Ammonia, hydrogen, and IPN were mixed and then entered the reactor. The ratio of ammonia to IPN was 1.2-2.5:1 (molar ratio), and the ratio of hydrogen to IPN was 3-10:1 (molar ratio). The reaction pressure is 0.3-0.8Mpa, and the temperature is 100-300°C. The overall airspeed is controlled at 50-200h ^-1 .

At present, IPN prepares IPDA, which is a two-step reaction. The first step is that IPN reacts with ammonia through an acidic catalyst (silicon, titanium oxide) to generate IPDI, and then IPDI reacts with hydrogen and liquid ammonia through a Raney catalyst to generate IPDA. Since the first step is a reversible reaction, the high conversion rate of IPN cannot be guaranteed, and the IPN regenerated by the reverse reaction will be directly hydrogenated to generate aminoalcohol in the second step, which is unfavorable to the quality of the product. This patent couples the Raney catalyst to the acidic catalyst through a certain scheme to produce a dual-functional catalyst with both imidization and amination hydrogenation. The previous two-step reaction is directly upgraded to a one-step reaction, which greatly improves the conversion rate and selectivity.

The pressures mentioned in the present invention are gauge pressures.

The positive effects of the present invention are:

(1) The traditional IPN hydrogenation to prepare IPDA skeleton Co catalyst is easy to pulverize the polluted materials during the reaction process, and the strength is low. However, the catalyst obtains a high-strength shaped skeleton cobalt catalyst through reasonable shaping means, which improves the mechanical strength of the catalyst while not affecting the hydrogenation effect of the catalyst. Thus, the stability and safety in the reaction evaluation process are indirectly improved.

(2) Zirconia is introduced into the catalyst during the molding process, and its presence will provide certain acidic sites, which is conducive to promoting the positive progress of the imidization reaction of isophorone nitrile. As a Schiff base, isophoronenitrile imine is unstable, and is easily hydrolyzed to generate isophoronenitrile, and the direct hydrogenation of isophoronenitrile will affect the yield of the reaction. As an active site for protecting isophorone nitrile imine, the acidic site can significantly reduce the amount of by-products in the product, thereby improving the activity and stability of the catalyst.

Detailed ways

In order to better understand the present invention, the content of the present invention is further illustrated below in conjunction with the examples, but the content of the present invention is not limited to the following examples.

The specific surface area and the pore structure of the catalyst microspheres are measured by the _N2 adsorption method (BET) used in the examples of the present invention. The instrument model is: ASP2020, produced by the American Mike Instrument Company.

The inductively coupled plasma optical emission spectrometer (ICP-OES) used in the examples of the present invention is produced by Agilent Technologies, model 720ICP-OES.

The particle strength measuring instrument used in the embodiment of the present invention is a digital display particle strength measuring instrument of Jiangyan Analytical Instrument Factory, the model is KC-3.

The gas chromatographic analysis conditions used in the examples of the present invention are: Agilent DB-5 chromatographic column, inlet temperature: 280°C; detector temperature: 280°C; H _flow rate: 35ml/min; air flow rate: 360ml/min. The heating program of the column oven is: initial temperature -100°C, heating rate is 20°C/min, keep for 1min; 100-280°C, heating rate is 15°C/min, keep for 8min.

Example 1

Mix 350g of cobalt metal and 650g of metal aluminum into a melting crucible. Then put the crucible in the melting furnace, raise the temperature to 1700°C, keep it for 5min, and start stirring at the same time, the stirring rate is 40r/min. After completion, the molten slurry is poured on a graphite plate, cooled naturally to room temperature, and an alloy block is obtained. A crusher is used to crush the alloy block into powder, and a 200-300-mesh sample is screened out with a sieve to obtain alloy powder. Take 50g of alloy powder, 6.55g of scallop powder, 0.3g of copper powder, and 0.2g of magnesium powder, mix them evenly, and set aside.

20g of tetrabutyl zirconate, 40g of deionized water and 160g of ruthenium acetate were mixed, and sulfuric acid was added to adjust the pH to 3. After stirring for 24 hours, 40 g of alloy powder doped with binder and metal was added. Press into a cylinder with a diameter of 2mm and a height of 3.5mm. Dry at 100°C for 12 hours and set aside.

Put it in a reaction tube for in-situ activation, use 25wt% sodium hydroxide solution, circulate at 70°C for 2 hours, and have a space velocity of 8h ^-1 . After completion, wash with deionized water until neutral to obtain a catalyst.

The obtained catalyst was characterized, and its BET specific surface area was measured to be 62 m ² /g, and its compressive strength was 340 N/particle.

The catalyst was evaluated for IPN to IPDA reaction. 50mL of catalyst was loaded into a single-tube reactor with a space velocity of 50h ^-1 , the molar ratio of ammonia to IPN was 1.2:1, the molar ratio of hydrogen to IPN was 3.2:1, the reaction pressure was 0.3Mpa, and the temperature was 100°C. Continuously run for 100 hours, take a sample every 10h for chromatographic analysis. The results are as follows: the average conversion rate of IPN is 99.3%, the average selectivity of IPDA is 99.9%, and the other products (mainly aminoalcohol) are 0.8%. The product was analyzed by ICP-OES, and the existence of metals such as Co and Al was not found, indicating that the catalyst was not pulverized, and the shape of the catalyst remained intact.

Example 2

The preparation mode of Co-Al alloy powder is with reference to embodiment 1.

Take 50g of alloy powder, 3g of graphite, 0.5g of boron powder, and 0.2g of magnesium powder, mix them evenly, and set aside.

20g of tetrabutyl zirconate, 60g of deionized water and 80g of ruthenium acetate were mixed, and sulfuric acid was added to adjust the pH to 1.5. After stirring for 48 hours, 25 g of alloy powder doped with binder and metal was added. Press into a cylinder with a diameter of 2.5mm and a height of 3.5mm. Dry at 80°C for 9 hours and set aside.

Place in a reaction tube for in-situ activation, take 20wt% sodium hydroxide solution, and circulate at 60°C for 3h. The airspeed is set at 11h ^-1 . After completion, wash with deionized water until neutral to obtain a catalyst.

The obtained catalyst was characterized, and its BET specific surface area was measured to be 65 m ² /g, and its pressure test strength was 335 N/particle.

The catalyst was evaluated for IPN to IPDA reaction. 50mL of catalyst was loaded into a single-tube reactor with a space velocity of 120h ^-1 , the molar ratio of ammonia to IPN was 1.85:1, the molar ratio of hydrogen to IPN was 6.5:1, the reaction pressure was 0.52Mpa, and the temperature was 150°C. Continuously run for 100 hours, take a sample every 10h for chromatographic analysis. The results are as follows: the average conversion rate of IPN is 100%, the average selectivity of IPDA is 99.3%, and other products (mainly aminoalcohol) are 0.5%. The product was analyzed by ICP-OES, and the existence of metals such as Co and Al was not found, indicating that the catalyst was not pulverized, and the shape of the catalyst remained intact.

Example 3

The preparation method of Co—Al alloy powder refers to Example 1, and the mass ratio of cobalt to aluminum alloy is 1.3.

Take 50g of alloy powder, 9g of cellulose, 0.8g of molybdenum powder, and 0.2g of phosphorus powder, mix them evenly, and set aside.

20g of tetrabutyl zirconate, 80g of deionized water and 100g of ruthenium acetate were mixed, and sulfuric acid was added to adjust the pH to 2.5. After stirring for 24 hours, 25 g of alloy powder doped with binder and metal was added. Press into a cylinder with a diameter of 2mm and a height of 4.5mm. Dry at 90°C for 6 hours and set aside.

Put the metal sheet into the reaction tube, take 25wt% sodium hydroxide solution, and circulate at 80°C for 1.5h. The airspeed is set at 18h ^-1 . After completion, wash with deionized water until neutral to obtain a catalyst.

The obtained catalyst was characterized, and its BET specific surface area was measured to be 65 m ² /g, and its pressure test strength was 320 N/particle.

The catalyst was evaluated for IPN to IPDA reaction. 50mL of catalyst was loaded into a single-tube reactor with a space velocity of 200h ^-1 , a molar ratio of ammonia to IPN of 2.4:1, a molar ratio of hydrogen to IPN of 9.5:1, a reaction pressure of 0.75Mpa, and a temperature of 260°C. Continuously run for 100 hours, take a sample every 10h for chromatographic analysis. The results were as follows: the average conversion rate of IPN was 100%, the average selectivity of IPDA was 99.9%, and no aminoalcohol was detected. The product was analyzed by ICP-OES, and the existence of metals such as Co and Al was not found, indicating that the catalyst was not pulverized, and the shape of the catalyst remained intact.

Comparative example 1

A commercially available catalyst for the preparation of IPDA by hydrogenation of IPN (purchased from Grace Chemicals, USA) was used for characterization and evaluation with reference to the evaluation method in Example 1. The company's industrial catalyst production method is to directly activate the alloy block, without the step of extrusion. The measured specific surface area was 61m ² /g, the pressure test strength was 290N/particle, the average conversion rate of IPN was 99.5%, and the average selectivity of IPDA was 99.1%. At the same time, a small amount of Co was detected in the reaction solution, indicating that the catalyst was pulverized. The catalytic performance of this catalyst is slightly worse than the catalyst performance of this patent.

Comparative example 2

Referring to the preparation method of the Raney catalyst in Example 2 of the patent CN1557918A, the Ni-Al alloy is replaced by a Co-Al alloy. The catalyst was characterized. The specific surface area of the catalyst was 25 m ² /g, and the pressure test strength was 200 N/particle. The reaction evaluation was also carried out with reference to the method of Example 1, the average conversion rate of IPN was 96.3%, and the average selectivity of IPDA was 98.2%. The catalytic performance of this catalyst is poorer than the performance of this patent.

Claims (10)

1. a preparation method of bifunctional molding framework cobalt catalyst, is characterized in that, described method comprises: (1) Co-Al alloy is prepared, then it is broken into alloy powder, and a certain amount of metal auxiliary agent and binder are mixed in; (2) preparing zirconia synthetic gel; (3) Mixing the product obtained in step (1) and step (2), drying, pressing into tablets, and activating with lye in situ to obtain a catalyst. 2. The method according to claim 1, characterized in that: the mass ratio of cobalt to aluminum in the Co-Al alloy powder prepared in step (1) is 0.5-1.5, and the particle size of the alloy powder obtained by crushing is between 100-400 mesh. 3. The method according to claim 1 or 2, characterized in that: the selected binding agent of step (1) is graphite, Tian Qing powder, one or more in cellulose, and the addition is 5-20wt%, based on the quality of alloy powder. 4. according to the method described in any one in claim 1-3, it is characterized in that: used metal assistant in step (1) is Ca, Mg, P, Ni, Pt, Cr, Co, Ti, Mg, B, Zn, one or more in Mo, addition is 0.1-5wt%, based on the quality of alloy powder. 5. according to the method described in any one in claim 1-4, it is characterized in that: in step (2) with a certain amount of tetrabutyl zirconate, water, ruthenium acetate mix, three mass ratios are 1: x: y, wherein x is 1-20, and y is 1-10. Then add sulfuric acid to adjust the pH to 1-5, and stir for 5-72 hours to obtain a zirconia synthetic gel. 6. The method according to any one of claims 1-5, characterized in that: the alloy powder and zirconia gel are mixed at a mass ratio of 1:5-15, and stirred evenly. 7. The method according to any one of claims 1-6, characterized in that: in step (3), the drying temperature is 80-100° C., and the drying time is 6-12 hours. 8. The method according to any one of claims 1-7, characterized in that: the tablet grinding tool is a cylinder with a diameter of 1-5mm and a height of 2-6mm. 9. The method according to any one of claims 1-8, characterized in that: the concentration of lye required for in-situ activation is 5-30wt%; the temperature required for the activation process is 60-90°C, and the activation time is 1-3h; the space velocity of lye during activation is controlled at 5-20h ^-1 . 10. The catalyst prepared by the method according to any one of claims 1-9 is applied to 3-cyano-3,5,5-trimethylcyclohexanone (IPN) amination hydrogenation to prepare 3-aminomethyl-3,5,5 trimethylcyclohexylamine (IPDA).