阅读说明：本技术 用于合成2-氨基丙醇的催化剂及其制备方法和使用 (Catalyst for synthesizing 2-aminopropanol and preparation method and application thereof ) 是由 陈健 张书 杭建荣 于 2020-06-10 设计创作，主要内容包括：本发明公开了用于合成2-氨基丙醇的催化剂的制备方法,步骤为：(1)制备沉淀剂溶液；(2)将镍盐、铝盐及活性金属盐加入水中,制成盐溶液；将沉淀剂溶液滴加到该盐溶液中,并进行老化；(3)老化后,过滤,将沉淀物洗涤并干燥后得前驱体；(4)将前驱体焙烧、研磨及活化后,制得该催化剂。以及采用上述方法制备的催化剂和该催化剂的应用。本申请中的所制备的催化剂具有更大的比表面积,同时由于采用共沉淀的方式,使催化剂中各中金属元素的分布更加均匀,比表面大,能够提高催化剂的催化活性。催化剂主要用于硝基丙醇催化加氢合成2-氨基丙醇工艺,具有较强的针对性,能够提高反应的转化率和选择性,以提高原料的利用率,降低生产成本。(The invention discloses a preparation method of a catalyst for synthesizing 2-aminopropanol, which comprises the following steps: (1) preparing a precipitant solution; (2) adding nickel salt, aluminum salt and active metal salt into water to prepare a salt solution; dripping a precipitant solution into the salt solution, and aging; (3) after aging, filtering, washing and drying the precipitate to obtain a precursor; (4) the precursor is roasted, ground and activated to prepare the catalyst. As well as a catalyst prepared by the method and application of the catalyst. The prepared catalyst has larger specific surface area, and simultaneously, the distribution of metal elements in the catalyst is more uniform and the specific surface area is large due to the adoption of a coprecipitation mode, so that the catalytic activity of the catalyst can be improved. The catalyst is mainly used for a process for synthesizing 2-aminopropanol by catalytic hydrogenation of nitropropanol, has strong pertinence, and can improve the conversion rate and selectivity of the reaction, so as to improve the utilization rate of raw materials and reduce the production cost.)

1. The preparation method of the catalyst for synthesizing the 2-aminopropanol is characterized by comprising the following steps:

(1) adding an alkaline precipitant into water, and dissolving at 50-90 ℃ to form a precipitant solution;

(2) adding nickel salt, aluminum salt and active metal salt into water, and dissolving at 50-90 ℃ to prepare a salt solution;

then maintaining the temperature of the salt solution, dropwise adding the precipitant solution prepared in the step (1) into the salt solution, and aging after dropwise adding;

(3) after aging, filtering to obtain a precipitate, washing and drying the precipitate to obtain a precursor;

(4) the precursor is roasted, ground and activated to prepare the catalyst.

2. The production method according to claim 1,

in the step (1), the alkaline precipitant is at least one of sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, ammonium carbonate and ammonium bicarbonate.

3. The production method according to claim 1,

the amount of alkaline precipitant used is 1.05-1.20 times the theoretical amount required to completely precipitate the metal ions in the active metal salt.

4. The production method according to claim 1,

in the step (2), the active metal salt is nitrate, sulfate, acetate or chloride, and the active metal is Cu, Co or Cr.

5. The production method according to claim 1,

the molar ratio of Al to Ni is 0.6-1.5: 1;

the molar ratio of the metal element to Ni in the active metal salt is 0.01-0.1: 1.

6. The production method according to claim 1,

in the step (2), the aging temperature is 50-90 ℃, and the aging time is 1-6 h; the precipitation temperature is 50-90 ℃;

in the step (3), the drying temperature is 50-120 ℃, and the drying time is 3-14 h.

7. The production method according to claim 1,

in the step (4), the roasting temperature is 300-600 ℃, and the roasting time is 1-10 h.

8. The production method according to claim 1,

in the step (4), activation is carried out in the atmosphere of hydrogen, the activation temperature is 400-700 ℃, and the activation time is 1-4 hours.

9. A catalyst prepared by the method of any one of claims 1 to 8.

10. Use of a catalyst according to claim 9, characterized in that: the method is used for synthesizing the 2-aminopropanol by catalytic hydrogenation of the nitropropanol.

Technical Field

The invention relates to the technical field of catalysis, in particular to a catalyst for synthesizing 2-aminopropanol and a preparation method and application thereof.

Background

The 2-aminopropanol is an important raw material, an intermediate and a chiral auxiliary agent in the pharmaceutical and agricultural product industries, particularly has wide application as a chiral source and a chiral modifier in asymmetric synthesis, and can be used as a low-temperature crystallization inhibitor of biomass and an entrainer for separating a mixture of primary amine and tertiary amine by azeotropic distillation besides the main application. With the continuous reduction of the cost of the 2-aminopropanol and the continuous expansion of the application range, the use amount of the 2-aminopropanol in various industries is expected to be greatly increased.

The preparation method of 2-aminopropanol is various, wherein the catalytic hydrogenation method has the characteristic of green chemical reaction, and is more and more concerned and researched by people. In the patent CN101648879A, L-alanine and H2 are used as main raw materials, ruthenium carbon is used as a catalyst, and the L-2-aminopropanol is synthesized by direct catalytic hydrogenation.

U.S. Pat. No. 6,639,10254 uses alanine as raw material, and synthesizes 2-aminopropanol by catalytic hydrogenation in ruthenium catalyst after acidification with inorganic acid or organic acid.

Chinese patent CN102344378A dissolves aqueous amino acid in water solution or mixed solvent of water and water miscible solvent, and synthesizes amino alcohol by one-step hydrogen reduction under the action of catalyst (Ru, Pd and third component).

Chinese patent CN103153942A provides a process for the manufacture of aminoalcohol compounds, 2-aminopropanol synthesized by the catalytic hydrogenation of nitroalcohols. The catalyst is selected from Raney nickel or platinum-or palladium-based catalysts (Pt or Pd in elemental form or as an oxide, with or without a support such as carbon), preferably Raney nickel.

The catalyst used in the method mostly adopts noble metal catalysts such as ruthenium, palladium and the like, the components are complex and expensive, the cost is high, and the Raney nickel catalyst has poor catalytic effect.

Disclosure of Invention

The invention aims to solve the problems of the existing hydrogenation catalyst and provides a catalyst for synthesizing 2-aminopropanol and a preparation method thereof.

In order to achieve the purpose, the invention adopts the following technical scheme:

a method for preparing a catalyst for the synthesis of 2-aminopropanol, comprising the steps of:

(1) adding an alkaline precipitant into water, and dissolving at 50-90 ℃ to form a precipitant solution;

(2) adding nickel salt, aluminum salt and active metal salt into water, and dissolving at 50-90 ℃ to prepare a salt solution;

then maintaining the temperature of the salt solution, dropwise adding the precipitant solution prepared in the step (1) into the salt solution, and aging after dropwise adding;

(3) after aging, filtering to obtain a precipitate, washing and drying the precipitate to obtain a precursor;

(4) the precursor is roasted, ground and activated to prepare the catalyst.

After the firing of the precursor is completed, the aluminum element is formed into alumina.

Preferably, in the step (2), the active metal salt is nitrate, sulfate, acetate or chloride, and the active component is Cu, Co or Cr.

In the application, a coprecipitation mode is adopted, firstly, nickel salt, aluminum salt and active metal salt form a composite salt crystal with uniformly distributed elements, and then the composite salt crystal is used as a precursor to be roasted, ground and activated. Compared with the existing alloy type catalyst represented by a Raney nickel catalyst, the prepared catalyst has larger specific surface area, and simultaneously, the distribution of metal elements in the catalyst is more uniform and the specific surface area is large due to the adoption of a coprecipitation mode, so that the catalytic activity of the catalyst can be improved.

In the application, the aluminum element in the catalyst exists in the form of alumina, and the alumina serving as a carrier does not have a catalytic effect, so that the generated alumina has a large specific surface area and a proper pore structure, and the catalytic activity of Ni and other active metals is improved.

In the invention, a certain amount of active metal is added on the basis of the supported nickel-based catalyst to be matched with the nickel metal, so that the overall activity of the catalyst is improved.

The catalyst prepared by the invention is mainly used for a process for synthesizing 2-aminopropanol by catalytic hydrogenation of nitropropanol, has stronger pertinence, and can greatly improve the conversion rate and selectivity of the reaction so as to improve the utilization rate of raw materials and reduce the production cost.

The catalyst prepared by the invention has the advantages of uniform distribution of active components, low-price active components and low cost. The obtained catalyst is used for synthesizing 2-aminopropanol by catalytic hydrogenation of nitropropanol, and has excellent activity and selectivity.

Further, in order to fully precipitate metal ions, improve the uniformity of precipitation and obtain a proper crystal structure, in the step (1), the alkaline precipitator is one or more of sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, ammonium carbonate and ammonium bicarbonate. The alkaline precipitator is used excessively to make metal ion precipitate completely, and in the application, the usage amount of the alkaline precipitator is 105-120% of the theoretical amount required by metal ion complete precipitation.

The addition of excessive precipitant can raise the pH value, affect the uniform dispersion degree and crystal structure of the precipitate, and thus affect the catalytic effect of the catalyst.

Further, preferably, the molar ratio of Al to Ni is 0.6-1.5: 1, the molar ratio of the metal element in the active metal salt to Ni is 0.01-0.1: 1. The Al and the Ni can exert the synergistic effect of the Al and the Ni only under the proper proportion to play a role in catalysis, and the nickel cannot be uniformly distributed on the surface of the alumina carrier due to the excessively low proportion to influence the catalysis effect; if the ratio is too high, the nickel metal content is low, and the catalytic effect is reduced. Tests show that under the limit of the molar ratio, the catalytic function of Ni can be maximized, and after a proper amount of active metal elements are added, the catalyst effect can be further improved under the promotion of the active metal elements, especially the addition of Cu, Co or Cr can effectively improve the activity of the catalyst, and improve the reaction conversion rate and the product selectivity.

In the step (2), the aging temperature is 50-90 ℃, and the aging time is 1-6 h; the precipitation temperature is 50-90 ℃; in the step (3), the drying temperature is 50-120 ℃, and the drying time is 3-14 h. In the present application, it is preferred that the precipitation temperature is the same as the aging temperature, i.e., that aging and precipitation are accomplished at the same temperature. The purpose of aging is to allow the precipitate particles to grow and perfect or transform the crystal form while allowing the gel to syneresis. In the present application, there is no special requirement for the aging process of the precipitate, and the aging process can be completed by the conventional technology without limitation.

Under the conditions, the crystal nucleus generation speed and the growth speed can be effectively controlled, so that a proper crystal structure is obtained. The method improves a good foundation for subsequent roasting, and ensures that the roasted material has a large number of fine pore passages so as to ensure the specific surface area of the catalyst and improve the service efficiency of the catalyst.

Preferably, in the step (4), the roasting temperature is 300-600 ℃, and the roasting time is 1-10 h. Preferably, the activation is carried out in the atmosphere of hydrogen, the activation temperature is 400-700 ℃, and the activation time is 1-4 h.

Under the condition, the components in the precursor can be ensured to be reacted and converted, impurities are removed, the specific surface area is increased, the mechanical strength is improved, and the required oxide or single body is finally generated, so that the catalyst has higher activity. If the roasting temperature is too high, part of metal elements can be sintered, the specific surface area of the catalyst is reduced, and the pore structure is damaged. The roasting temperature is too low to completely decompose the metal hydroxide, and at the roasting temperature and the roasting time, all components in the precursor can be completely oxidized, impurities such as chemically combined water and the like are removed, the specific surface area is increased, and the mechanical strength is improved.

Too high an activation temperature may reduce the specific surface area of the catalyst and destroy the pore structure. The activation temperature is too low to reduce nickel oxide into metallic nickel, and at the activation temperature and in the activation time, the nickel oxide can be completely reduced into metallic nickel without influencing the catalyst structure.

The method of filtration, washing and drying is not particularly limited in the present invention, and a method well known in the art may be used.

The application also provides a catalyst prepared by adopting any one of the technical schemes.

The application also provides an application of the catalyst, and the catalyst is used for synthesizing 2-aminopropanol by catalytic hydrogenation of nitropropanol. When the catalyst is used for synthesizing the 2-aminopropanol, the existing nitropropanol catalytic hydrogenation process is adopted.

The catalyst is prepared from nickel salt, aluminum salt and metal salt containing active components in a specific ratio by a coprecipitation method and is used for synthesizing 2-aminopropanol by catalytic hydrogenation of nitropropanol.

Compared with the prior art, the invention has the beneficial effects that: the catalyst prepared by the invention has the advantages of uniform distribution of active components, low-price active components and low cost. The obtained catalyst is used for synthesizing 2-aminopropanol by catalytic hydrogenation of nitropropanol, and has excellent activity and selectivity. Especially, when the active metal is Cu or Cr, the catalyst has better selectivity and conversion rate, wherein the selectivity reaches over 99.0 percent, and the conversion rate reaches 99.0 percent. When the active metal is Co, although the effect is slightly lower than that of Cu or Cr, the selectivity reaches about 98.8%, and the conversion rate reaches over 99.0%. All have a certain degree of improvement compared with the case of no active metal, and especially have better effect on conversion rate.

Detailed Description