阅读说明：本技术 甘氨酸的制备方法 (Preparation method of glycine ) 是由 黄义争 高进 徐杰 孙颖 苗虹 车鹏华 石松 马红 于 2019-11-05 设计创作，主要内容包括：本申请公开了一种甘氨酸的制备方法。该制备方法包括将含有乙醇胺和水的物料,在氧源存在的条件下,与催化剂接触,反应,得到甘氨酸；其中,所述催化剂为负载在载体上的金属催化剂；所述载体为氮掺杂碳/固体碱载体；所述催化剂通过含氮有机化合物、固体碱和金属源制备得到。本申请提供的乙醇胺直接催化氧化制备甘氨酸的方法,具有反应路线绿色清洁,原料成本低、转化率和产物选择性高、催化剂可循环使用等优势。(The application discloses a preparation method of glycine. The preparation method comprises the steps of enabling a material containing ethanolamine and water to contact with a catalyst in the presence of an oxygen source to react to obtain glycine; wherein the catalyst is a metal catalyst supported on a carrier; the carrier is a nitrogen-doped carbon/solid base carrier; the catalyst is prepared from a nitrogen-containing organic compound, a solid base and a metal source. The method for preparing the glycine by directly catalyzing and oxidizing the ethanolamine has the advantages of green and clean reaction route, low raw material cost, high conversion rate and product selectivity, recyclable catalyst and the like.)

1. A preparation method of glycine is characterized in that a material containing ethanolamine and water is contacted with a catalyst in the presence of an oxygen source to react to obtain glycine;

wherein the catalyst is a carrier-supported metal catalyst;

the carrier is a nitrogen-doped carbon/solid base carrier;

the catalyst is prepared from a nitrogen-containing organic compound, a solid base and a metal source.

2. The production method according to claim 1, wherein the nitrogen-containing organic compound is a multidentate nitrogen-containing organic compound.

3. The preparation method according to claim 2, wherein the multidentate nitrogen-containing organic compound is at least one selected from the group consisting of benzimidazole, benzotriazole, ethylenediamine, 1, 2-cyclohexanediamine, phenanthroline, and 2, 2' -bipyridine.

4. The method according to claim 1, wherein the solid base is at least one selected from magnesium hydroxide, hydrotalcite, NaX molecular sieve, NaY molecular sieve.

5. The method according to claim 1, wherein the metal is at least one selected from the group consisting of gold, cobalt, palladium, and platinum.

6. The method according to claim 1, wherein the method for preparing the catalyst comprises at least the following steps:

and roasting a mixture containing a nitrogen-containing organic compound, solid alkali and a metal source to obtain the catalyst.

7. The preparation method according to claim 6, wherein the mass ratio of the solid base to the nitrogen-containing organic compound is 2-5: 1;

preferably, the mass ratio of the nitrogen-containing organic compound to the metal source is 2-5: 1;

preferably, the roasting conditions are as follows: roasting at 500-700 ℃; the roasting time is 1-3 h.

8. The preparation method according to claim 1, wherein the amount of the catalyst is 0.1-2% by mass of ethanolamine;

preferably, the mass percentage of the ethanolamine in the reaction system is 10-50%;

wherein the reaction system comprises ethanolamine, water and a catalyst;

preferably, the reaction conditions are: the reaction temperature is 100-150 ℃; the reaction pressure is 0.3-2.0 MPa; the reaction time is 4-12 h.

Technical Field

The application relates to a preparation method of glycine, and belongs to the technical field of organic chemical industry.

Background

Glycine, also known as glycine, is an important organic chemical raw material, is an edible spice which is allowed to be used in the food safety national standard food additive use standard (GB 2760) of China, is also used as a preservative and an antioxidant of medicines, feeds and foods, is used for treating symptoms such as myasthenia gravis, progressive muscular atrophy, hyperacidity, chronic enteritis, hyperprolemia of children and the like in the medicine industry, and is also used for synthesizing medicines such as L-dopa, vitamin B6, threonine, cephalosporin, thiamphenicol, delapril hydrochloride, calcium oxalglycine aspirin, paracetamol glycinate, calcium monoacylglycine acetylsalicylate, reserpidine and the like, and pesticides such as pyrethroid insecticides, iprodione bactericides, glyphosate herbicides, glyphosine and plant growth regulators.

The conventional preparation method of glycine has the following problems: (1) the schterek (Strecker) method. Taking formaldehyde, hydrocyanic acid and ammonia as raw materials, synthesizing aminoacetonitrile, and hydrolyzing to obtain glycine. (2) The Bucherer method. The glycine is synthesized by using trioxymethylene, ammonium carbonate, sodium cyanide and the like as raw materials. (3) Monochloroacetic acid ammoniation method. The glycine is synthesized by using ammonia water and monochloroacetic acid as raw materials. The method has the advantages of difficult control of selectivity, easy generation of byproducts such as iminodiacetic acid, nitrilotriacetic acid and the like, low glycine selectivity, high raw material consumption and the need of using chlorine as the raw material for producing the monochloroacetic acid. The three methods have the problems of large raw material toxicity and environmental influence, poor safety and the like.

In recent years, technical routes such as preparation of ethylene glycol from coal/synthesis gas and preparation of ethylene glycol from biomass have been developed. The ethylene glycol is aminated to prepare the ethanolamine. The high-value utilization of ethylene glycol, ethanolamine and other substances has important significance for increasing economic benefits and promoting the development of industries such as coal-to-ethylene glycol and the like. The ethanolamine can be dehydrogenated, oxidized and converted into aminoacetate under the existence of alkali metal or alkaline earth metal and Raney Cu catalyst, and then neutralized by acid to obtain glycine. The method needs to consume metered acid and alkali, generates a large amount of salt-containing wastewater, and has the disadvantages of serious corrosion of equipment, high consumption of raw materials and great environmental influence.

Disclosure of Invention

In order to solve the outstanding problems of high raw material toxicity and environmental influence, poor safety, high raw material consumption, high environmental influence and the like in the traditional preparation method of the glycine, and the consumption of acid and alkali for preparing the glycine by dehydrogenation and oxidation of ethanolamine, the application provides a method for preparing the glycine by direct catalytic oxidation of the ethanolamine, and the method has the advantages of green and clean reaction route, low raw material cost, high conversion rate and product selectivity, recyclable catalyst and the like.

The technical scheme adopted by the invention is as follows: contacting a material containing ethanolamine and water with a catalyst in the presence of an oxygen source, and reacting to obtain glycine;

wherein the catalyst is a carrier-supported metal catalyst;

the carrier is a nitrogen-doped carbon/solid base carrier;

the catalyst is prepared from a nitrogen-containing organic compound, a solid base and a metal source.

Specifically, in the present application, the oxygen source is oxygen gas or air.

Optionally, the nitrogen-containing organic compound is a multidentate nitrogen-containing organic compound.

According to the present invention, the multidentate nitrogen-containing compound plays two roles: (1) the chelating action is generated with metal, so that the metal component is fixed and is not easy to run off, and the reduction of the activity of the catalyst caused by the complexation of ethanolamine or glycine with metal can be prevented; (2) the nitrogen has larger electronegativity than carbon, and can generate positive charge polarization effect on adjacent carbon atoms, improve the positive charge density of the adjacent carbon atoms, facilitate the adsorption of oxygen molecules, promote the oxidation reaction and improve the conversion rate of ethanolamine.

Optionally, the multidentate nitrogen-containing compound is at least one of benzimidazole, benzotriazole, ethylenediamine, 1, 2-cyclohexanediamine, phenanthroline, and 2, 2' -bipyridyl.

According to the present invention, the alkaline environment facilitates the catalytic oxidative conversion of ethanolamine to glycine. The invention develops a nitrogen-doped carbon/solid alkali supported metal catalyst, constructs an alkaline catalysis microenvironment, promotes the oxidation reaction, and improves the conversion rate of ethanolamine and the selectivity of glycine.

Optionally, the solid base is selected from at least one of magnesium hydroxide, hydrotalcite, NaX molecular sieve, NaY molecular sieve.

Alternatively, the metal component in the catalyst of the present invention is at least one selected from gold, cobalt, palladium, and platinum, which have catalytic activity for selectively oxidizing a hydroxyl group in ethanolamine to a carboxyl group.

Optionally, the preparation method of the catalyst at least comprises the following steps:

and roasting a mixture containing a nitrogen-containing organic compound, solid alkali and a metal source to obtain the catalyst.

Specifically, a solution I containing a metal source and a solution II containing a nitrogen-containing organic compound are mixed, stirred for 1-3 hours, added with solid alkali, stirred for 3-5 hours at 50-70 ℃, dried, and roasted in an inactive atmosphere to obtain the catalyst.

Wherein, in the solution I, the solvent is methanol;

in the solution II, the solvent is methanol;

the inert atmosphere is either nitrogen or an inert gas.

Optionally, the metal source is selected from at least one of cobalt acetate and hexahydrate, chloroauric acid, palladium chloride, chloroplatinic acid.

Optionally, the mass ratio of the solid base to the nitrogen-containing organic compound is 2-5: 1.

optionally, the mass ratio of the nitrogen-containing organic compound to the metal source is 2-5: 1.

optionally, the roasting conditions are: roasting at 500-700 ℃; the roasting time is 1-3 h.

Optionally, the amount of the catalyst is 0.1-2% of the mass of the ethanolamine.

Optionally, the ethanolamine is 10-50% by mass in the reaction system.

The reaction system comprises ethanolamine, water and a catalyst.

Optionally, the reaction conditions are: the reaction temperature is 100-150 ℃; the reaction pressure is 0.3-2.0 MPa; the reaction time is 4-12 h.

In the present application, the term "multidentate nitrogen-containing organic compound" refers to a nitrogen-containing compound containing at least two nitrogen atoms in one molecule;

the beneficial effects that this application can produce include:

the method has the advantages that air or oxygen is used as an oxygen source, water is used as a solvent, ethanolamine is directly catalyzed and oxidized to prepare the glycine in the presence of a nitrogen-doped carbon/solid alkali supported metal catalyst, the ethanolamine conversion rate and the glycine selectivity can reach 99% to the maximum, a reaction route is green and clean, the raw material cost is low, the conversion rate and the product selectivity are high, and the catalyst can be recycled.

Detailed Description

The present application will be described in detail with reference to examples, but the present application is not limited to these examples.

The raw materials in the examples of the present application were all purchased commercially, unless otherwise specified.

In the examples of the present application, the ethanolamine conversion and glycine selectivity were calculated as follows:

example 1

Dissolving 1g of hydrated cobalt acetate in 100mL of methanol, adding the mixture into 100mL of methanol in which 2g of benzimidazole is dissolved under stirring, continuously stirring for 2h, adding 5g of NaY molecular sieve, stirring for 4h at 60 ℃, evaporating the solvent, drying the obtained solid at 80 ℃ for 2h, roasting at 600 ℃ for 2h under the protection of nitrogen to obtain a nitrogen-doped carbon/NaY molecular sieve supported cobalt catalyst (Co-N-C/NaY), adding 20mg of the catalyst into a 50mL reaction kettle filled with 2g of ethanolamine and 8g of deionized water, stirring, heating to 100 ℃, filling oxygen to the pressure of 1.0MPa, reacting for 8h, and carrying out qualitative and quantitative analysis on the reaction product through gas chromatography-mass spectrometry, wherein the conversion rate of the ethanolamine is 99% and the selectivity of the glycine is 99%.

Examples 2 to 11

Examples 2-11 the results of using different catalysts were studied, and the procedure was similar to example 1, except that different metal sources and different solid alkali or metal oxide supports were used, the catalysts were calcined at different temperatures for different times, and the reaction conditions were otherwise the same as in example 1, and the results are shown in table 1.

Example 2 differs from example 1 in that: the metal source was 0.6g chloroauric acid; the solid base was 10g Mg (OH)₂(ii) a Roasting at 500 ℃ for 3 h; finally obtaining the nitrogen-doped carbon/magnesium hydroxide load gold catalyst (Au-N-C/Mg (OH)₂)。

Example 3 differs from example 1 in that: the metal source was 0.8g of palladium chloride; the solid alkali is 8g of NaX molecular sieve; roasting at 700 ℃ for 1 h; finally obtaining the nitrogen-doped carbon/NaX molecular sieve supported palladium catalyst (Pd-N-C/NaX).

Example 4 differs from example 1 in that: the metal source was 0.4g chloroplatinic acid; the solid alkali is 4g of NaX molecular sieve; roasting for 2h at 700 ℃; finally obtaining the nitrogen-doped carbon/hydrotalcite-loaded palladium catalyst (Pt-N-C/hydrotalcite).

Example 5 differs from example 1 in that: the metal source was 1g of copper acetate monohydrate; finally obtaining the nitrogen-doped carbon/NaY molecular sieve loaded copper catalyst (Cu-N-C/NaY).

Example 6 differs from example 1 in that: the metal source is 1g of iron acetate; finally obtaining the nitrogen-doped carbon/NaY molecular sieve supported iron catalyst (Fe-N-C/NaY).

Example 7 differs from example 1 in that: the metal source was 1g of nickel acetate tetrahydrate; finally obtaining the nitrogen-doped carbon/NaY molecular sieve supported nickel catalyst (Ni-N-C/NaY).

Example 8 differs from example 1 in that: the metal oxide support was 2g of titanium dioxide; finally obtaining nitrogen-doped carbon/TiO₂Supported cobalt catalyst (Co-N-C/TiO)₂)。

Example 9 differs from example 1 in that: the metal oxide support was 2g of zirconium dioxide; finally obtaining nitrogen-doped carbon/ZrO₂Supported cobalt catalyst (Co-N-C/ZrO)₂)。

Example 10 differs from example 1 inIn the following steps: the metal oxide carrier is 2g of aluminum oxide; finally obtaining nitrogen-doped carbon/Al₂O₃Supported cobalt catalyst (Co-N-C/Al)₂O₃)。

Example 11 differs from example 1 in that: no NaY molecular sieve is added during the preparation of the catalyst, and finally the nitrogen-doped carbon supported cobalt catalyst (Co-N-C) is obtained; the catalysts added in the ethanolamine oxidation reaction are 20mg of Co-N-C and 10mg of NaY molecular sieve.

TABLE 1 Effect of different catalysts

Examples	Catalyst and process for preparing same	Ethanolamine conversion rate%	Glycine selectivity%
				1	Co-N-C/NaY	99	99
2	Au-N-C/Mg(OH)2	95	94
				3	Pd-N-C/NaX	86	85
4	Pt-N-C/hydrotalcite	90	95
				5	Cu-N-C/NaY	68	86
6	Fe-N-C/NaY	65	84
				7	Ni-N-C/NaY	62	82
8	Co-N-C/TiO2	90	46
				9	Co-N-C/ZrO2	89	40
10	Co-N-C/Al2O3	88	49
				11	Co-N-C+NaY	95	80

In examples 2 to 4, a nitrogen-doped carbon/magnesium hydroxide supported gold catalyst, a nitrogen-doped carbon/NaX molecular sieve supported palladium catalyst, and a nitrogen-doped carbon/hydrotalcite supported platinum catalyst were used, respectively, and both the ethanolamine conversion and the glycine selectivity were 85% or more.

In examples 5 to 7, copper, iron and nickel loaded on nitrogen-doped carbon/NaY molecular sieves are used as catalysts, and the selectivity of glycine can reach more than 80%, but the conversion rate of ethanolamine is not ideal.

Examples 8-10 use nitrogen-doped carbon/TiO, respectively₂Loaded cobalt and nitrogen doped carbon/ZrO₂Loaded cobalt and nitrogen doped carbon/Al₂O₃When the cobalt catalyst is loaded, the conversion rate of ethanolamine can reach about 90%, but the selectivity of glycine is less than 50%.

Example 11 a mixture of nitrogen-doped carbon-supported cobalt and NaY molecular sieves was used as the catalyst with 95% conversion of ethanolamine and 80% selectivity to glycine.

Examples 1 to 11 show that the metal component has a large influence on the reaction effect; solid alkali has certain influence on the conversion rate of ethanolamine, and has larger influence on the selectivity of glycine; the Co-N-C/NaY catalyst has better catalytic effect than a mixture of nitrogen-doped carbon-supported cobalt and NaY molecular sieve, and possibly the two components in the Co-N-C/NaY have synergistic action.

Examples 12 to 19

Examples 12-19 the effect of Co-N-C/NaY catalysts from different nitrogen-containing organic compounds on the reaction was studied, in a similar manner to example 1, except that the reaction conditions were the same as in example 1, and the results are shown in Table 2. In examples 12 to 16, Co-N-C/NaY prepared from nitrogen-containing organic compounds such as benzotriazole, ethylenediamine, 1, 2-cyclohexanediamine, phenanthroline and 2, 2' -bipyridine has a good catalytic effect, and the ethanolamine conversion rate and the glycine selectivity can reach over 90%. Examples 17 and 18 attempted to prepare Co-N-C/NaY catalysts with pyridine and triethylamine as nitrogen-containing organic compounds and used to catalyze ethanolamine conversions, with ethanolamine conversions of only about 15%. Example 19 using a cobalt on activated carbon/NaY molecular sieve catalyst, the ethanolamine conversion was lower. The results show that the Co-N-C/NaY catalyst prepared from the multidentate nitrogen-containing compounds such as benzimidazole, benzotriazole, ethylenediamine, 1, 2-cyclohexanediamine, phenanthroline, 2' -bipyridyl and the like is beneficial to the catalytic reaction.

TABLE 2 catalytic Effect of Co-N-C/NaY made with different Nitrogen-containing organic Compounds

Examples	Nitrogen-containing organic compound	Ethanolamine conversion rate%	Glycine selectivity%
				12	Benzotriazole	98	99
13	Ethylene diamine	96	98
				14	1, 2-cyclohexanediamine	92	97
15	Phenanthroline	90	92
				16	2, 2' -bipyridine	91	90
17	Pyridine compound	15	76
				18	Triethylamine	14	73
19	Is free of	8	52

Examples 20 to 25

Examples 20-25 the effect of the reaction conditions was studied and the procedure was similar to example 1 except that the reaction conditions were as shown in Table 3 and the other reaction conditions were the same as example 1 and the results are shown in Table 3. Co-N-C/NaY is used as a catalyst, the dosage of the catalyst is 0.1-2.0% of the mass of ethanolamine, the mass percentage of ethanolamine in a reaction system is 10-50%, the reaction temperature is 100-150 ℃, the reaction pressure is 0.3-2.0MPa, the reaction time is 4-12h, and the ethanolamine conversion rate and the glycine selectivity can both reach more than 85%.

TABLE 3 influence of reaction conditions on the Co-N-C/NaY catalytic Effect

Example 26

Example 26 study the catalyst recycling effect in example 1, after the reaction in example 1, the catalyst was attracted by a magnet, after the liquid was removed, 2g ethanolamine and 8g deionized water were added to the reaction kettle to continue the reaction, and the reaction conditions were the same as in example 1, and the ethanolamine conversion and glycine selectivity were both 99%. The catalyst is recycled, and the ethanolamine conversion rate and the glycine selectivity are both 99%.

In the invention, air or oxygen is used as an oxygen source, water is used as a solvent, and ethanolamine is directly catalyzed and oxidized to prepare glycine under the condition of the existence of a nitrogen-doped carbon-solid alkali supported metal catalyst, wherein the ethanolamine conversion rate and the glycine selectivity can reach 99 percent at most, and the method has the advantages of green and clean reaction route, low raw material cost, high conversion rate and product selectivity, recyclable catalyst and the like.

Although the present application has been described with reference to a few embodiments, it should be understood that various changes, substitutions and alterations can be made herein without departing from the spirit and scope of the application as defined by the appended claims.