CN101683618A - Catalyst used for preparing amino acid salt through low-temperature oxidative dehydrogenation by using amino alcohol - Google Patents

Abstract

The invention provides a catalyst using Cu/ _ZrO2 as the main catalyst and palladium as a co-catalyst for the low-temperature oxidative dehydrogenation of amino alcohols to prepare amino acid salts. The catalyst has good low-temperature activity, high selectivity and stability, and the catalyst The preparation condition is simple and can be used in the industrial production of amino acid salts. The invention adopts amino alcohol and alkali metal hydroxide as raw materials, reacts to generate amino acid salt under the action of catalyst under the condition of relatively low reaction temperature of 140-180 DEG C and reaction pressure of 0.5-1.0 MPa. The technical scheme adopted in the invention better solves the problem of serious corrosion of production equipment under the condition of high temperature and strong alkali reaction.

Description

A kind of catalyst for the low-temperature oxidative dehydrogenation of amino alcohol to prepare amino acid salt

technical field

The invention relates to a catalyst for preparing amino acid salts by low-temperature oxidative dehydrogenation of amino alcohols.

Background technique

Amino acid salts can be neutralized into amino acids, which are important organic chemical raw materials and can be used to synthesize herbicide glyphosate, dyes, food additives, special synthetic resins, water treatment agents, etc.

Using amino alcohol and alkali metal hydroxide as raw materials, the production process of directly oxidizing and dehydrogenating amino acid salt under the action of a catalyst has the characteristics of economy, environmental protection, low production cost, high product yield and good product quality. The key to this process lies in the selection and preparation of the catalyst.

In 1974, in the patent US3842081, Heinz Schulze and others used cadmium oxide as a catalyst and reacted at 250°C to prepare amino acid salts. Although the catalyst has good activity, the reaction temperature is high, and cadmium will cause serious water pollution.

In 1988, in the patent US4782183, Goto et al. proposed a non-toxic and non-cadmium-based catalyst, which contained copper or a compound of copper and zirconium. Compared with the cadmium-based catalyst, this type of catalyst can make amino alcohol at a temperature of 160°C-190°C °C and a pressure of 0.9 MPa, the reaction has a higher yield of amino acid salt, and the service time of the catalyst is prolonged, which reduces the reaction cost. The catalysts reported in this patent include Raney-Cu catalysts, metal copper catalysts after reducing and thermally decomposing copper formate, copper-zirconium catalysts prepared by co-precipitation methods, and copper-zirconium catalysts prepared by impregnation methods. However, with the repeated use of the catalyst, its reactivity and selectivity decreased.

In 1993, in the patent US5220055, Urano et al proposed to add 0.002-0.5% metal aluminum in the oxidative dehydrogenation reaction system in order to reduce the reaction by-products, increase the reaction yield and selectivity, and improve the reuse rate of the catalyst. and (or) aluminum compounds (the patent proposes to use sodium aluminate or aluminum hydroxide for better effect). In 1994, in patents US5292936 and _US5739390 , Franczyk et al. added 50-5000ppm of chromium, titanium, nickel, tantalum, zirconium, vanadium, molybdenum, manganese, tungsten, cobalt, The metals of nickel, bismuth, tin, antimony, lead, germanium or their mixtures can improve the reuse rate of the catalyst. Although these metals can improve the stability of copper catalysts, after a period of use, these metals will leach out in the reaction solution and the stabilizing effect will be reduced.

In 1997, in the patent US5627125, Ebner et al. reported the preparation of a supported active copper catalyst with activated carbon as a carrier by electroless plating. Compared with the Raney Cu catalyst and the supported copper catalyst prepared by the co-precipitation method, the catalyst prepared by the electroless plating method has higher activity and can shorten the reaction time. Although the catalyst can shorten the reaction time, the noble metal (platinum, palladium) content of activated carbon support is relatively large (greater than 2.1wt%), and the amount of catalyst used in the reaction is also large (40% of the amino alcohol amount), so that the production cost increases , and using activated carbon as a carrier, the volume occupied by the catalyst is large, and the catalyst treatment is troublesome, which reduces the production capacity.

In 2001, Zeng Xiaojun et al. reported the amorphous Raney Cu catalyst. Although the catalyst has high catalytic activity, selectivity and stability, the reaction temperature and pressure are still high, and the material requirements for the production equipment are high, and the molten metal is required to be quenched during the catalyst preparation process, and the catalyst preparation conditions are harsh.

In 2002, in the patent US6376708, Morgenstern et al. reported a copper catalyst supported by a metal carrier (especially a metal sponge carrier). This catalyst does not use noble metals, has low cost, has a high surface area, and is not easy to be sintered and deactivated under reaction conditions. , and wear resistance, filterability is good, but the target product selectivity is poor. In 2006, Morgenstern et al reported in the patent US7126024 an iron-modified sponge nickel-supported copper catalyst, which reduces the formation of by-products and improves the selectivity of amino acid salts. In 2008, Morgenstern et al. reported a copper catalyst supported by a copper-doped sponge nickel carrier in the patent US7329778. Although the yield of amino acid salt was improved, there was still the problem of poor selectivity of the target product.

Since the reaction involved in the above-mentioned patent is usually carried out above 160°C, the high temperature and strong alkali reaction conditions cause serious corrosion to the equipment, so the development and preparation conditions are simple, and the catalyst with good low temperature activity, high selectivity and stability is suitable for It plays an important role in reducing equipment investment and production costs and improving product quality.

Contents of the invention

The purpose of the present invention is to provide a catalyst preparation method and a low-temperature amino alcohol oxidative dehydrogenation reaction process to solve the problem of severe corrosion of production equipment under the high-temperature strong alkali reaction conditions of the existing amino alcohol oxidative dehydrogenation amino acid salt production equipment.

The preparation method of catalyst of the present invention comprises the following steps:

(1) A copper salt solution with a concentration of 0.05-1mol/L and a zirconium salt solution with a concentration of 0.05-1mol/L are configured into a mixed solution with a copper-zirconium atomic ratio of 0.1-2, and the mixed solution is mixed with a concentration of 0.5 ～6.0mol/L alkaline solution is co-precipitated under the conditions of 40～80℃ and pH value of 6～11;

Co-precipitation method, selected from one of forward addition, reverse addition and co-current addition;

The copper salt used is selected from any one of copper nitrate, copper acetate, copper chloride, and copper sulfate; the zirconium salt used can be zirconium nitrate, zirconium oxychloride, zirconium sulfate, zirconium acetate; the alkali used is selected from hydrogen Any one of calcium oxide, sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, sodium bicarbonate, potassium bicarbonate;

(2) Aging the precipitate obtained in step (1) at 50-100° C. for 2-8 hours, and drying at 60-120° C. for 8-24 hours after washing.

(3) After heat-treating the solid obtained in step (2) for 1 to 6 hours at 150 to 300° C., impregnating it with a palladium salt solution, aging it for 4 to 20 hours, and then drying it at 60 to 120° C. for 4 to 10 hours, Roast at 300-600°C for 1-6 hours; the roasted solid is reduced by temperature programming method, the heating rate is 1-20°C/min, the final reduction temperature is 150-600°C, and the volume content of reducing gas is 20 ～100%, the rest is nitrogen, and the total flow rate of reducing gas is 10～60ml/min. The reduced catalyst is protected in lye to prevent oxidation by air.

(4) After the solid obtained in step (2) is roasted at 300-600°C for 1-6 hours, it is reduced by a temperature-programmed method, the heating rate is 1-20°C/min, and the final reduction temperature is 150-600°C, The volume content of reducing gas is 20-100%, the rest is nitrogen, and the total flow rate of reducing gas is 10-60ml/min; after the reduced solid is soaked in palladium salt solution for 5-300min, add alkali solution to adjust the pH value to 6-6 13. Add a reducing agent with a concentration of 5-40%, and reduce for 30-300 minutes at a temperature of 30-80°C.

The reducing agent used is any one selected from formaldehyde, potassium borohydride, sodium hypophosphite, ascorbic acid, and hydrazine hydrate.

The atomic ratio of copper and zirconium in the involved catalyst is 0.1-2, and the loading amount of palladium is 0.025%-2%.

The present invention can be used in the reaction of amino alcohol to prepare amino acid salt, and the amino alcohol involved is selected from monoethanolamine, diethanolamine, triethanolamine, 2-aminopropanol, N-methylethanolamine, N-methyldiethanolamine, N,N ,N',N',-Tetrakis(2-hydroxyethyl)ethylenediamine; the reaction involves the conversion of monoethanolamine to glycinate, diethanolamine to iminodiacetate, and triethanolamine to nitrilotriacetic acid , 2-aminopropanol is converted to alanine salt, N-methylethanolamine is converted to N-methylglycinate, N-methyldiethanolamine is converted to N-methyliminodiacetate, N, N, N',N',-Tetrakis(2-hydroxyethyl)ethylenediamine is converted into ethylenediamine tetraacetate;

The method of amino alcohol system amino acid salt among the present invention is as follows:

Add a certain proportion of catalyst, amino alcohol and alkali metal hydroxide aqueous solution to the autoclave in sequence, close the autoclave, replace the air in the autoclave with nitrogen pressure, then start the agitator and start heating. React for 5 hours at a reaction temperature of 140°C-180°C and a reaction pressure of 0.5MPa-1.0MPa. The catalyst can be used repeatedly without regeneration.

The invention adopts copper salt, zirconium salt, alkali solution and palladium salt as raw materials, and the catalyst is prepared through the steps of precipitation, drying, impregnation, temperature-programmed hydrogen reduction or liquid phase reduction and the like. The catalyst has simple preparation conditions, is used for oxidative dehydrogenation of amino alcohols, has good low-temperature activity, high selectivity and stability, and better solves the problem of serious corrosion of production equipment under high-temperature strong alkali reaction conditions.

Detailed ways

Example 1

Copper nitrate and zirconium oxychloride are formulated into 400ml of a mixed solution with a total metal ion concentration of 0.3mol/L according to the copper-zirconium atomic ratio of 0.6:1, and the mixed solution and a sodium hydroxide solution with a concentration of 4.4mol/L are added dropwise Put it into a 1000ml three-neck flask, keep the precipitation temperature at 60°C, and the pH value of the precipitation at 9. After the precipitation is completed, age the precipitate at 80°C for 4 hours, dry the precipitate at 110°C for 12 hours after washing, and then heat-treat it at 250°C for 3 hours. After 1 hour, impregnate palladium chloride solution, wherein the palladium load is 2000ppm, after 12 hours of immersion, dry at 110°C for 4 hours, and roast at 500°C for 4 hours, and the solid after roasting is subjected to temperature-programmed reduction in 60ml/min reducing gas , wherein the concentration of hydrogen in the reducing gas is 90%, the heating rate is 5°C/min, and the final reduction temperature is 410°C. After keeping for 4 hours, the catalyst is lowered to room temperature to prepare the catalyst.

Example 2

Add 68.8g diethanolamine, 60.2g sodium hydroxide, 6.9g embodiment 1 catalyst and 140.5g water in 450ml nickel autoclave. Seal the autoclave, pressurize and replace it with nitrogen three times to remove the air in the autoclave, then heat it to 160°C, and keep the pressure in the autoclave at 0.8Mpa. After reacting for 5 hours, the conversion rate of diethanolamine was 91.8%, and the selectivity of iminodiacetate was 87.6%.

Example 3

Copper nitrate and zirconium oxychloride are formulated into 400ml of a mixed solution with a total metal ion concentration of 0.3mol/L according to the copper-zirconium atomic ratio of 0.6:1, and the mixed solution and a sodium hydroxide solution with a concentration of 4.4mol/L are added dropwise Put it into a 1000ml three-neck flask, keep the precipitation temperature at 60°C, and the pH value of the precipitation at 9.0. After the precipitation is completed, age the precipitate at 80°C for 4 hours, wash the precipitate and dry it at 110°C for 12 hours, and then roast it at 500°C 4 hours. The calcined solid is subjected to temperature-programmed reduction in 60ml/min reducing gas, wherein the hydrogen concentration in the reducing gas is 90%, the heating rate is 5°C/min, and the final reduction temperature is 210°C. After 4 hours, it is lowered to room temperature Prepare Cu/ZrO2 catalyst. Put the Cu/ZrO2 catalyst into 0.045mol/L palladium chloride solution and immerse it for 1 hour, add 5% sodium hydroxide solution dropwise, adjust the pH to 8.5, and add 10% formaldehyde according to the molar ratio of formaldehyde/palladium to 10 The solution was reduced at 60° C. for 4 hours to prepare a Pd-Cu/ZrO2 catalyst with a palladium loading of 2000 ppm. Add 68.8g of diethanolamine, 60.2g of sodium hydroxide, 6.9g of the catalyst and 140.5g of water into a 450ml nickel autoclave. Seal the autoclave, pressurize and replace it with nitrogen three times to remove the air in the autoclave, then heat it to 160°C, and keep the pressure in the autoclave at 0.8Mpa. After reacting for 5 hours, the conversion rate of diethanolamine was 93.0%, and the selectivity of iminodiacetate was 90.0%.

Example 4

Copper nitrate and zirconium oxychloride are formulated into 400ml of a mixed solution with a total metal ion concentration of 0.4mol/L according to the copper-zirconium atomic ratio of 1:1, and the mixed solution is gradually added dropwise to 80ml of sodium hydroxide with a concentration of 4.0mol/L In the solution, the precipitation temperature was kept at 70°C, and the pH value of the precipitation was 11. After the precipitation was completed, the precipitate was aged at 70°C for 4 hours, washed and dried at 110°C for 12 hours, and then calcined at 450°C for 4 hours. The calcined solid is subjected to temperature-programmed reduction in 60ml/min reducing gas, wherein the hydrogen concentration in the reducing gas is 90%, the heating rate is 5°C/min, and the final reduction temperature is 300°C. After 4 hours, it is lowered to room temperature Prepare Cu/ZrO2 catalyst. Put the Cu/ZrO2 catalyst into a 0.045mol/L palladium chloride solution and immerse it for 1 hour, add 8% sodium hydroxide solution dropwise, adjust the pH to 9, and add 10% formaldehyde according to the ratio of formaldehyde/palladium molar ratio of 9 The solution was reduced at 60° C. for 4 hours to prepare a Pd-Cu/ZrO2 catalyst with a palladium loading of 2500 ppm. Add 62.5g of diethanolamine, 58.2g of sodium hydroxide, 6.3g of the catalyst and 130.5g of water into a 450ml nickel autoclave. Seal the autoclave, pressurize and replace it with nitrogen three times to drain the air in the autoclave, and then heat it to 150°C to keep the pressure in the autoclave at 0.8Mpa. After reacting for 5 hours, the conversion rate of diethanolamine was 91.2%, and the selectivity of iminodiacetate was 84.5%.

Example 5

Prepare copper acetate and zirconium nitrate at a copper-zirconium atomic ratio of 0.8:1 to make 400ml of a mixed solution with a total metal ion concentration of 0.5mol/L, and gradually add a potassium hydroxide solution with a concentration of 4.5mol/L to the above mixed solution , keep the precipitation temperature at 60°C, and the precipitation pH value at 9. After the precipitation is completed, age the precipitate at 80°C for 4 hours, wash the precipitate and dry it at 110°C for 12 hours, and then bake it at 450°C for 6 hours. The roasted solid is subjected to temperature-programmed reduction in a reducing gas of 50ml/min, wherein the hydrogen concentration in the reducing gas is 90%, the heating rate is 5°C/min, and the final reduction temperature is 250°C. After 4 hours, it is lowered to room temperature Prepare Cu/ZrO2 catalyst. Put the Cu/ZrO2 catalyst into the concentration of 0.035mol/L palladium acetate solution and soak for 2 hours, add dropwise 5% sodium hydroxide solution, adjust the pH to 8.5, add 10% formaldehyde solution according to the ratio of formaldehyde/palladium molar ratio of 10 ,, and reduced at 50°C for 4 hours to prepare a Pd-Cu/ZrO2 catalyst with a palladium loading of 2500 ppm. Add 60.0 g of monoethanolamine, 52.2 g of sodium hydroxide, 6.0 g of the catalyst and 110.5 g of water in a 450 ml nickel autoclave. Seal the autoclave, pressurize and replace it with nitrogen three times to drain the air in the autoclave, and then heat it to 150°C to keep the pressure in the autoclave at 0.8Mpa. After reacting for 5 hours, the conversion rate of monoethanolamine was 92.4%, and the selectivity of glycinate was 86.6%.

Example 6

Copper nitrate and zirconium oxychloride are formulated into 400ml of a mixed solution with a total concentration of metal ions of 0.3mol/L according to the copper-zirconium atomic ratio of 0.6:1, and the mixed solution and a concentration of 3mol/L are added dropwise to the sodium bicarbonate solution at the same time In a 1000ml three-neck flask, keep the precipitation temperature at 60°C and the pH value of the precipitation at 9.0. After the precipitation is completed, age the precipitate at 80°C for 4 hours, wash the precipitate and dry it at 110°C for 12 hours, and then roast it at 500°C for 4 hours. Hour. The roasted solid is subjected to temperature-programmed reduction in 60ml/min reducing gas, wherein the hydrogen concentration in the reducing gas is 90%, the heating rate is 5°C/min, and the final reduction temperature is 250°C. After 4 hours, it is lowered to room temperature Prepare Cu/ZrO2 catalyst. The Cu/ZrO2 catalyst input concentration is that 0.045mol/L palladium chloride solution is immersed for 1 hour, and 10% sodium hydroxide solution is added dropwise, and the pH is adjusted to 10, and the ratio of hydrazine hydrate/palladium molar ratio is 8 to add 10% Hydrazine hydrate solution was reduced at 60° C. for 4 hours to prepare a Pd-Cu/ZrO2 catalyst with a palladium loading of 2500 ppm. Add 68.8g of diethanolamine, 60.2g of sodium hydroxide, 13.8g of the catalyst and 140.5g of water into a 450ml nickel autoclave. Seal the autoclave, pressurize and replace it with nitrogen three times to remove the air in the autoclave, then heat it to 140°C, and keep the pressure in the autoclave at 0.5Mpa. After reacting for 5 hours, the conversion rate of diethanolamine was 96.6%, and the selectivity of iminodiacetate was 94.1%.

Example 7

Copper nitrate and zirconium oxychloride are formulated into 400ml of a mixed solution with a total metal ion concentration of 0.3mol/L according to the copper-zirconium atomic ratio of 0.6:1, and the mixed solution and a sodium hydroxide solution with a concentration of 4.4mol/L are added dropwise Put it into a 1000ml three-neck flask, keep the precipitation temperature at 70°C, and the precipitation pH value at 11. After the precipitation is completed, age the precipitate at 70°C for 4 hours, wash the precipitate and dry it at 110°C for 12 hours, and then roast it at 500°C 4 hours. The roasted solid is subjected to temperature-programmed reduction in 60ml/min reducing gas, wherein the hydrogen concentration in the reducing gas is 50%, the heating rate is 5°C/min, and the final reduction temperature is 300°C. After 4 hours, it is lowered to room temperature Prepare Cu/ZrO2 catalyst. Put the Cu/ZrO2 catalyst into 0.045mol/L palladium chloride solution and immerse it for 1 hour, add 5% sodium hydroxide solution dropwise, adjust the pH to 10, and add 10% formaldehyde according to the ratio of formaldehyde/palladium molar ratio of 10 The solution was reduced at 70°C for 4 hours to prepare a Pd-Cu/ZrO2 catalyst with a palladium loading of 1000ppm. Add 68.8g of diethanolamine, 60.2g of sodium hydroxide, 6.9g of the catalyst and 160.2g of water into a 450ml nickel autoclave. Seal the autoclave, pressurize and replace it with nitrogen three times to drain the air in the autoclave, then heat it to 170°C, and keep the pressure in the autoclave at 0.8Mpa. After reacting for 5 hours, the conversion rate of diethanolamine was 98.3%, and the selectivity of iminodiacetate was 97.1%.

Claims (6)

1. the preparation method of amino alcohol low-temperature oxidative dehydrogenation amino acid salt catalyst, is characterized in that, comprises the steps: (1) Precipitate the mixed solution of copper salt and zirconium salt and alkali solution at 40-80°C and a pH value of 6-11; (2) Aging the precipitate obtained in step (1) at 50-100°C for 2-8 hours, after washing, drying at 60-120°C for 8-24 hours; (3) After heat-treating the solid obtained in step (2) for 1 to 6 hours at 150 to 300° C., impregnating the palladium salt solution, aging for 4 to 20 hours, drying at 60 to 120° C. for 4 to 10 hours, and Roasting at 300-600°C for 1-6 hours; the calcined solid is reduced by temperature programming method, the heating rate is 1-20°C/min, the final reduction temperature is 150-600°C, and the volume content of reducing gas is 20- 100%, the rest is nitrogen, and the total flow rate of reducing gas is 10-60ml/min. The reduced catalyst is protected in lye to prevent oxidation by air. (4) After the solid obtained in step (2) is roasted at 300-600°C for 1-6 hours, it is reduced by a temperature-programmed method, the heating rate is 1-20°C/min, and the final reduction temperature is 150-600°C, The volume content of reducing gas is 20-100%, the rest is nitrogen, and the total flow rate of reducing gas is 10-60ml/min; after the reduced solid is soaked in palladium salt solution for 5-300min, add alkali solution to adjust the pH value to 6-6 13. Add a reducing agent with a concentration of 5-40%, and reduce for 30-300 minutes at a temperature of 30-80°C. 2. The catalyst according to claim 1, characterized in that the copper salt used is selected from any one in copper nitrate, copper acetate, copper chloride, copper sulfate; the zirconium salt used can be zirconium nitrate, oxychloride Zirconium chloride, zirconium sulfate, zirconium acetate; Used alkali is selected from any one in calcium hydroxide, sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, sodium bicarbonate, potassium bicarbonate; Used palladium salt is selected from Any one of palladium nitrate, palladium acetate, palladium chloride, palladium sulfate. 3. The catalyst according to claim 1, characterized in that the co-precipitation method is selected from one of forward addition, reverse addition and co-current addition. 4. Catalyst according to claim 1, is characterized in that, used reducing agent is selected from the one in formaldehyde, potassium borohydride, sodium hypophosphite, ascorbic acid, hydrazine hydrate. 5. The catalyst according to claim 1, characterized in that the atomic ratio of copper and zirconium in the catalyst involved is 0.1-2, and the loading amount of palladium is 0.025%-2%. 6. the application of catalyst according to claim 5, is applied in amino acid oxidative dehydrogenation and prepares amino acid salt reaction.