阅读说明：本技术 2,6-二甲基哌嗪裂解生产异丙醇胺和1,2-丙二胺的方法 (Method for producing isopropanolamine and 1, 2-propane diamine by cracking 2, 6-dimethylpiperazine ) 是由 陈国华 郭文杰 曹振力 于 2021-01-29 设计创作，主要内容包括：本发明属于有机合成技术领域,具体的涉及一种2,6-二甲基哌嗪裂解生产异丙醇胺和1,2-丙二胺的方法。2,6-二甲基哌嗪在Co-Mo-Pd/Al-2O-3催化剂作用下,进行接触裂解反应,制得异丙醇胺和1,2-丙二胺的混合物,再通过蒸馏分离得到纯净的异丙醇胺和1,2-丙二胺。本发明所述的2,6-二甲基哌嗪裂解生产异丙醇胺和1,2-丙二胺的方法,采用Co-Mo-Pd/Al-2O-3催化剂进行裂解反应,该催化剂具有比表面积高、机械强度高、稳定性好的优点,且制备过程简单,对2,6-二甲基哌嗪裂解有很高的催化活性。(The invention belongs to the technical field of organic synthesis, and particularly relates to a method for producing isopropanolamine and 1, 2-propane diamine by cracking 2, 6-dimethylpiperazine. 2, 6-dimethylpiperazine in Co-Mo-Pd/Al 2 O 3 Under the action of a catalyst, a contact cracking reaction is carried out to prepare a mixture of isopropanolamine and 1, 2-propane diamine, and pure isopropanolamine and 1, 2-propane diamine are obtained through distillation and separation. The method for producing isopropanolamine and 1, 2-propane diamine by cracking 2, 6-dimethyl piperazine adopts Co-Mo-Pd/Al 2 O 3 The catalyst has the advantages of high specific surface area, high mechanical strength, good stability, simple preparation process and high catalytic activity on 2, 6-dimethyl piperazine cracking.)

1. A method for producing isopropanolamine and 1, 2-propane diamine by cracking 2, 6-dimethyl piperazine is characterized by comprising the following steps: 2, 6-dimethylpiperazine in Co-Mo-Pd/Al₂O₃Under the action of a catalyst, a contact cracking reaction is carried out to prepare a mixture of isopropanolamine and 1, 2-propane diamine, and pure isopropanolamine and 1, 2-propane diamine are obtained through distillation and separation.

2. The process for the production of isopropanolamine and 1, 2-propanediamine from the cleavage of 2, 6-dimethylpiperazine according to claim 1, characterized in that: the Co-Mo-Pd/Al₂O₃The catalyst comprises, by weight of metal oxide, CoO accounting for 1-3% of the weight of the catalyst, MoO accounting for 1-3% of the weight of the catalyst, and PdO accounting for 2-4% of the weight of the catalyst.

3. The process for the production of isopropanolamine and 1, 2-propanediamine from the cleavage of 2, 6-dimethylpiperazine according to either one of claims 1 or 2, characterized in that: the Co-Mo-Pd/Al₂O₃The pore volume of the catalyst is 0.3-0.8ml/g, the specific surface area is 200-350m²/g。

4. The process for the production of isopropanolamine and 1, 2-propanediamine from the cleavage of 2, 6-dimethylpiperazine according to claim 1, characterized in that: the method comprises the following steps:

(1) introducing 2, 6-dimethyl piperazine into a vaporizer of a reaction system, heating and gasifying the mixture gas of ammonia and water, and then mixing the mixture gas with Co-Mo-Pd/Al in the reactor₂O₃Carrying out contact cracking reaction on the catalyst;

(2) and (2) condensing the product obtained in the step (1), and then feeding the product into a distillation separation system to obtain pure isopropanolamine and 1, 2-propane diamine.

5. The method for producing isopropanolamine and 1, 2-propanediamine according to claim 4, wherein said cracking of 2, 6-dimethylpiperazine is characterized in that: the temperature of the mixed gas of ammonia and water in the step (1) is 200-300 ℃; the volume ratio of the ammonia gas to the water vapor is 1: 2-1: 3.

6. The method for producing isopropanolamine and 1, 2-propanediamine according to claim 4, wherein said cracking of 2, 6-dimethylpiperazine is characterized in that: the pressure of the contact cracking reaction in the step (1) is 10-15 atmospheric pressures, and the time of the contact cracking reaction is 30-60 min.

7. The process for the production of isopropanolamine and 1, 2-propanediamine from the cleavage of 2, 6-dimethylpiperazine according to claim 1, characterized in that: the Co-Mo-Pd/Al₂O₃The preparation method of the catalyst comprises the following steps:

(1) adding a sodium hydroxide solution into aluminum hydroxide, uniformly mixing, adding nitric acid for neutralization, then aging, filtering, washing, rolling ball molding, drying and roasting to prepare a spherical alumina carrier with the diameter of 3-5 mm;

(2) mixing nitrate solutions of Co, Mo and Pd according to a specific ratio to prepare a catalyst impregnation solution, pre-impregnating an alumina carrier to obtain a wet-ball carrier, drying and roasting;

(3) cooling the catalyst precursor prepared in the step (2), soaking the catalyst precursor in the catalyst soaking solution prepared in the step (2), taking out the catalyst precursor, drying and roasting the catalyst precursor to obtain Co-Ni-Pd/Al₂O₃Catalyst and process for preparing same。

8. The process for the production of isopropanolamine and 1, 2-propanediamine from the cleavage of 2, 6-dimethylpiperazine according to claim 7, characterized in that: adding a sodium hydroxide solution in the step (1), mixing for 1-3h, adding nitric acid for neutralization, wherein the neutralization time is 30-60 min;

the aging temperature in the step (1) is 80-120 ℃, and the aging time is 2-5 h; washing with water; the drying temperature is 100-150 ℃, and the drying time is 3-5 h; the roasting temperature is 300-500 ℃, and the roasting time is 1-4 h.

9. The process for the production of isopropanolamine and 1, 2-propanediamine from the cleavage of 2, 6-dimethylpiperazine according to claim 7, characterized in that: the mass fraction of the cobalt nitrate solution in the step (2) is 5-20%; the mass fraction of the molybdenum nitrate solution is 5-20%; the mass fraction of the palladium nitrate solution is 5-20%;

the pre-impregnation time in the step (2) is 1-2 h.

10. The process for the production of isopropanolamine and 1, 2-propanediamine from the cleavage of 2, 6-dimethylpiperazine according to claim 7, characterized in that:

cooling to 20-40 ℃ in the step (3), and soaking again for 1-2 h;

when the steeping liquor in the step (2) and the step (3) is steeped, adopting equal-volume steeping;

the drying and roasting process parameters in the step (2) and the step (3) are the same, and the drying temperature is 120-150 ℃ and the drying time is 3-5 h; the roasting temperature is 300-500 ℃, and the roasting time is 2-5 h.

Technical Field

The invention belongs to the technical field of organic synthesis, and particularly relates to a method for producing isopropanolamine and 1, 2-propane diamine by cracking 2, 6-dimethylpiperazine.

Background

The 1, 2-propane diamine is an organic chemical intermediate and a raw material with wide application, has important application in the fields of medicines, pesticides, organic synthesis, lubricating oil antirust agents, epoxy resin curing accelerators, spandex and modified shellac coatings and the like, and can be used as rubber, coatings, raw materials, chelating agents, mineral dressing agents and the like, and can be used for producing 1, 2-propane diamine tetraacetic acid as an intermediate of anticancer medicine propane imine.

Because the isopropanolamine has less harm to the environment and human body, the isopropanolamine becomes a green chemical product which is strongly advocated and encouraged in developed countries. Isopropanolamine is used for the synthesis of textile auxiliaries (finishing agents, antistatic agents, dyeing auxiliaries, penetrants), emulsifiers (for cutting oils, coatings, insecticides), polishes, tanning agents, plasticizers, etc.; also used as a non-aqueous catalyst for the pre-reaction of solvent-type chloroprene adhesive 2402 resin and active magnesium oxide. At the same time, isopropanolamine is also one of the important raw materials for preparing 1, 2-propanediamine.

Patent CN 201110449743.3 discloses a production process of 1, 2-propane diamine, adding isopropanolamine and a catalyst into a 1-liter pressure reaction kettle, and replacing air in the pressure reaction kettle with nitrogen for three times; then adding ammonia, wherein the molar ratio of isopropanolamine to ammonia is 1:1.2-1.3, and heating to 150-155 ℃ under stirring; introducing hydrogen to make the pressure reach 8-12MPa, and keeping the pressure with the hydrogen to react for 4-5 hours; after the reaction is finished, cooling the reaction solution to room temperature, emptying, and removing hydrogen in the reaction kettle by using nitrogen; filtering the reaction liquid to recover the catalyst, and rectifying the filtrate at normal pressure to obtain a finished product of the 1, 2-propane diamine; the catalyst is a mixture of NiO, CoO and CuO,the catalyst carrier is Al₂O₃The weight percentage of the catalyst is NiO 10%, CoO 10% and CuO 5%, and the dosage of the catalyst is 2-3% of the weight of isopropanolamine.

In the above reaction process, isopropanolamine as a raw material is combined with 1, 2-propanediamine as a product to produce a large amount of 2, 6-dimethylpiperazine as a by-product, which affects the yield, and 2, 6-dimethylpiperazine as a by-product has a low price and is not economical.

Patent CN111925341A discloses a method for preparing piperazine by diethanolamine in Co-Ni-Mo/Al₂O₃And (3) carrying out continuous gas-solid reaction under the action of a catalyst to prepare the piperazine. However, such catalysts have not been demonstrated in the laboratory for the cleavage of 2, 6-dimethylpiperazine.

Therefore, how to reuse 2, 6-dimethylpiperazine as a byproduct becomes a hot spot and a difficulty for researchers to study.

Disclosure of Invention

The purpose of the invention is: providing a method for producing isopropanolamine and 1, 2-propane diamine by cracking 2, 6-dimethyl piperazine; the method improves the economic value of the 2, 6-dimethylpiperazine, the reaction conditions are easy to control, and the prepared isopropanolamine and 1, 2-propane diamine have high purity and yield.

The method for producing isopropanolamine and 1, 2-propane diamine by cracking 2, 6-dimethylpiperazine is characterized in that 2, 6-dimethylpiperazine is subjected to Co-Mo-Pd/Al₂O₃Under the action of a catalyst, a contact cracking reaction is carried out to prepare a mixture of isopropanolamine and 1, 2-propane diamine, and pure isopropanolamine and 1, 2-propane diamine are obtained through distillation and separation.

The Co-Mo-Pd/Al₂O₃The catalyst comprises, by weight of metal oxide, CoO accounting for 1-3% of the weight of the catalyst, MoO accounting for 1-3% of the weight of the catalyst, and PdO accounting for 2-4% of the weight of the catalyst.

The Co-Mo-Pd/Al₂O₃The pore volume of the catalyst is 0.3-0.8ml/g, the specific surface area is 200-350m²/g。

Preferably, the method for producing isopropanolamine and 1, 2-propanediamine by cracking 2, 6-dimethylpiperazine according to the invention comprises the following steps:

(1) introducing 2, 6-dimethyl piperazine into a vaporizer of a reaction system, heating and gasifying the mixture gas of ammonia and water, and then mixing the mixture gas with Co-Mo-Pd/Al in the reactor₂O₃Carrying out contact cracking reaction on the catalyst;

(2) and (2) condensing the product obtained in the step (1), and then feeding the product into a distillation separation system to obtain pure isopropanolamine and 1, 2-propane diamine.

Wherein:

the temperature of the mixed gas of ammonia and water in the step (1) is 200-300 ℃.

The volume ratio of the ammonia gas to the water vapor in the step (1) is 1: 2-1: 3.

The pressure of the contact cracking reaction in the step (1) is 10-15 atmospheric pressures, and the time of the contact cracking reaction is 30-60 min.

And the unreacted 2, 6-dimethylpiperazine enters a vaporizer to participate in the next circulation.

And (3) the steam in the step (2) enters a condenser, is condensed to 60-80 ℃ and enters a distillation separation system, and the refrigerant is water.

The Co-Mo-Pd/Al₂O₃The preparation method of the catalyst comprises the following steps:

(1) adding a sodium hydroxide solution into aluminum hydroxide, uniformly mixing, adding nitric acid for neutralization, then aging, filtering, washing, rolling ball molding, drying and roasting to prepare a spherical alumina carrier with the diameter of 3-5 mm;

(2) mixing nitrate solutions of Co, Mo and Pd according to a specific ratio to prepare a catalyst impregnation solution, pre-impregnating an alumina carrier to obtain a wet-ball carrier, drying and roasting;

(3) cooling the catalyst precursor prepared in the step (2), soaking the catalyst precursor in the catalyst soaking solution prepared in the step (2), taking out the catalyst precursor, drying and roasting the catalyst precursor to obtain Co-Ni-Pd/Al₂O₃A catalyst.

Wherein:

the reaction equation involved in step (1) is:

NaOH+Al(OH)₃＝NaAlO₂+H₂O

NaAlO₂+H₂O+HNO₃＝Al(OH)₃↓+NaNO₃。

and (2) adding a sodium hydroxide solution in the step (1), mixing for 1-3h, adding nitric acid for neutralization, and neutralizing for 30-60 min.

The aging temperature in the step (1) is 80-120 ℃, and the aging time is 2-5 h; washing with water; the drying temperature is 100-150 ℃, and the drying time is 3-5 h; the roasting temperature is 300-500 ℃, and the roasting time is 1-4 h.

The mass fraction of the cobalt nitrate solution in the step (2) is 5-20%; the mass fraction of the molybdenum nitrate solution is 5-20%; the mass fraction of the palladium nitrate solution is 5-20%.

The pre-impregnation time in the step (2) is 1-2 h.

And (4) cooling to 20-40 ℃ in the step (3), and impregnating again for 1-2 h.

And (3) adopting equal-volume impregnation when impregnating in the impregnation liquid in the step (2) and the step (3).

The drying and roasting process parameters in the step (2) and the step (3) are the same, the drying temperature is 120-150 ℃, and the drying time is 3-5 h; the roasting temperature is 300-500 ℃, and the roasting time is 2-5 h.

The method for producing isopropanolamine and 1, 2-propane diamine by cracking 2, 6-dimethylpiperazine relates to the following reaction equation:

compared with the prior art, the invention has the following beneficial effects:

(1) the method for producing isopropanolamine and 1, 2-propane diamine by cracking 2, 6-dimethyl piperazine adopts Co-Mo-Pd/Al₂O₃The catalyst has high specific surface area, high mechanical strength and high stabilityHas the advantages of simple preparation process and high catalytic activity on the cracking of 2, 6-dimethyl piperazine.

(2) The method for producing isopropanolamine and 1, 2-propanediamine by cracking 2, 6-dimethylpiperazine catalytically cracks economically-worthless 2, 6-dimethylpiperazine into isopropanolamine and 1, 2-propanediamine, widens the application range of 2, 6-dimethylpiperazine, and has the advantages of simple cracking process, easily controlled parameters and easy realization of industrial popularization.

Detailed Description

The present invention is further described below with reference to examples.

Example 1

The method for producing isopropanolamine and 1, 2-propanediamine by cracking 2, 6-dimethylpiperazine described in example 1 consists of the following steps:

(1) introducing 2, 6-dimethyl piperazine into a vaporizer of a reaction system, heating and gasifying the mixture gas of ammonia and water, and then mixing the mixture gas with Co-Mo-Pd/Al in the reactor₂O₃Carrying out contact cracking reaction on the catalyst;

(2) and (2) condensing the product obtained in the step (1), and then feeding the product into a distillation separation system to obtain pure isopropanolamine and 1, 2-propane diamine.

Wherein:

the Co-Mo-Pd/Al₂O₃Catalyst, CoO is 2% of catalyst weight, MoO is 2% of catalyst weight, and PdO is 2% of catalyst weight.

The Co-Mo-Pd/Al₂O₃The catalyst has a pore volume of 0.5ml/g and a specific surface area of 280m²/g。

The temperature of the mixed gas of ammonia and water in the step (1) is 200 ℃.

The volume ratio of the ammonia gas to the water vapor in the step (1) is 1: 3.

The pressure of the contact cracking reaction in the step (1) is 15 atmospheric pressures, and the time of the contact cracking reaction is 40 min.

And the unreacted 2, 6-dimethylpiperazine enters a vaporizer to participate in the next circulation.

And (3) feeding the steam in the step (2) into a condenser, condensing the steam to 80 ℃, and feeding the steam into a distillation separation system, wherein the refrigerant is water.

The Co-Mo-Pd/Al₂O₃The preparation method of the catalyst comprises the following steps:

(1) adding a sodium hydroxide solution into aluminum hydroxide, uniformly mixing, adding nitric acid for neutralization, then aging, filtering, washing, rolling ball molding, drying and roasting to prepare a spherical alumina carrier with the diameter of 5 mm;

(2) mixing nitrate solutions of Co, Mo and Pd according to a specific ratio to prepare a catalyst impregnation solution, pre-impregnating an alumina carrier to obtain a wet-ball carrier, drying and roasting;

(3) cooling the catalyst precursor prepared in the step (2), soaking the catalyst precursor in the catalyst soaking solution prepared in the step (2), taking out the catalyst precursor, drying and roasting the catalyst precursor to obtain Co-Ni-Pd/Al₂O₃A catalyst.

Wherein:

the involved reaction equation is:

NaOH+Al(OH)₃＝NaAlO₂+H₂O

NaAlO₂+H₂O+HNO₃＝Al(OH)₃↓+NaNO₃。

and (2) adding a sodium hydroxide solution in the step (1), mixing for 3h, adding nitric acid for neutralization, and neutralizing for 60 min.

The aging temperature in the step (1) is 100 ℃, and the aging time is 4 h; washing with water; the drying temperature is 150 ℃, and the drying time is 4 hours; the roasting temperature is 500 ℃, and the roasting time is 3 hours.

The mass fraction of the cobalt nitrate solution in the step (2) is 10%; the mass fraction of the molybdenum nitrate solution is 10 percent; the mass fraction of the palladium nitrate solution is 10%.

The pre-impregnation time in the step (2) is 2 h.

And (4) cooling to 40 ℃ in the step (3), and impregnating again, wherein the impregnating time is 2 h.

And (3) adopting equal-volume impregnation when impregnating in the impregnation liquid in the step (2) and the step (3).

The drying and roasting process parameters in the step (2) and the step (3) are the same, and the drying time is 5 hours at the drying temperature of 150 ℃; the roasting temperature is 500 ℃, and the roasting time is 5 hours.

The detection shows that the isopropanolamine accounts for 48.38%, the 1, 2-propane diamine accounts for 49.65%, the water accounts for 1.49%, and the 2, 6-dimethyl piperazine accounts for 0.48%.

Example 2

The method for producing isopropanolamine and 1, 2-propanediamine by cracking 2, 6-dimethylpiperazine described in example 2 consists of the following steps:

(1) introducing 2, 6-dimethyl piperazine into a vaporizer of a reaction system, heating and gasifying the mixture gas of ammonia and water, and then mixing the mixture gas with Co-Mo-Pd/Al in the reactor₂O₃Carrying out contact cracking reaction on the catalyst;

(2) and (2) condensing the product obtained in the step (1), and then feeding the product into a distillation separation system to obtain pure isopropanolamine and 1, 2-propane diamine.

Wherein:

the Co-Mo-Pd/Al₂O₃The catalyst comprises 3% of CoO, 2% of MoO and 3% of PdO by weight of metal oxide.

The Co-Mo-Pd/Al₂O₃The catalyst has a pore volume of 0.8ml/g and a specific surface area of 350m²/g。

The temperature of the mixed gas of ammonia and water in the step (1) is 300 ℃.

The volume ratio of the ammonia gas to the water vapor in the step (1) is 1: 2.

The pressure of the contact cracking reaction in the step (1) is 12 atmospheric pressures, and the time of the contact cracking reaction is 50 min.

And the unreacted 2, 6-dimethylpiperazine enters a vaporizer to participate in the next circulation.

And (3) feeding the steam in the step (2) into a condenser, condensing the steam to 60 ℃, and feeding the steam into a distillation separation system, wherein the refrigerant is water.

The Co-Mo-Pd/Al₂O₃The preparation method of the catalyst comprises the following steps:

(1) adding a sodium hydroxide solution into aluminum hydroxide, uniformly mixing, adding nitric acid for neutralization, then aging, filtering, washing, rolling ball molding, drying and roasting to prepare a spherical alumina carrier with the diameter of 5 mm;

(2) mixing nitrate solutions of Co, Mo and Pd according to a specific ratio to prepare a catalyst impregnation solution, pre-impregnating an alumina carrier to obtain a wet-ball carrier, drying and roasting;

(3) cooling the catalyst precursor prepared in the step (2), soaking the catalyst precursor in the catalyst soaking solution prepared in the step (2), taking out the catalyst precursor, drying and roasting the catalyst precursor to obtain Co-Ni-Pd/Al₂O₃A catalyst.

Wherein:

the involved reaction equation is:

NaOH+Al(OH)₃＝NaAlO₂+H₂O

NaAlO₂+H₂O+HNO₃＝Al(OH)₃↓+NaNO₃。

and (2) adding a sodium hydroxide solution in the step (1), mixing for 2h, adding nitric acid for neutralization, and neutralizing for 50 min.

The aging temperature in the step (1) is 120 ℃, and the aging time is 3 h; washing with water; the drying temperature is 140 ℃, and the drying time is 5 hours; the roasting temperature is 450 ℃, and the roasting time is 3 hours.

The mass fraction of the cobalt nitrate solution in the step (2) is 15%; the mass fraction of the molybdenum nitrate solution is 10 percent; the mass fraction of the palladium nitrate solution is 15%.

The pre-impregnation time in the step (2) is 1.5 h.

And (4) cooling to 40 ℃ in the step (3), and impregnating again, wherein the impregnating time is 1.5 h.

And (3) adopting equal-volume impregnation when impregnating in the impregnation liquid in the step (2) and the step (3).

The drying and roasting process parameters in the step (2) and the step (3) are the same, the drying temperature is 145 ℃, and the drying time is 4 hours; the roasting temperature is 450 ℃, and the roasting time is 4 hours.

The detection shows that the isopropanolamine accounts for 48.36%, the 1, 2-propane diamine accounts for 47.58%, the water accounts for 2.37%, and the 2, 6-dimethyl piperazine accounts for 1.69%.

Example 3

The method for producing isopropanolamine and 1, 2-propanediamine by cracking 2, 6-dimethylpiperazine described in example 3 consists of the following steps:

(1) introducing 2, 6-dimethyl piperazine into a vaporizer of a reaction system, heating and gasifying the mixture gas of ammonia and water, and then mixing the mixture gas with Co-Mo-Pd/Al in the reactor₂O₃Carrying out contact cracking reaction on the catalyst;

(2) and (2) condensing the product obtained in the step (1), and then feeding the product into a distillation separation system to obtain pure isopropanolamine and 1, 2-propane diamine.

Wherein:

the Co-Mo-Pd/Al₂O₃The catalyst comprises 3% of CoO, 1% of MoO and 4% of PdO by weight of metal oxide.

The Co-Mo-Pd/Al₂O₃The catalyst has a pore volume of 0.3ml/g and a specific surface area of 200m²/g。

The temperature of the mixed gas of ammonia and water in the step (1) is 250 ℃.

The volume ratio of the ammonia gas to the water vapor in the step (1) is 2: 5.

The pressure of the contact cracking reaction in the step (1) is 10 atmospheric pressures, and the time of the contact cracking reaction is 60 min.

And the unreacted 2, 6-dimethylpiperazine enters a vaporizer to participate in the next circulation.

And (3) feeding the steam in the step (2) into a condenser, condensing the steam to 70 ℃, and feeding the steam into a distillation separation system, wherein the refrigerant is water.

The Co-Mo-Pd/Al₂O₃The preparation method of the catalyst comprises the following steps:

(1) adding a sodium hydroxide solution into aluminum hydroxide, uniformly mixing, adding nitric acid for neutralization, then aging, filtering, washing, rolling ball molding, drying and roasting to prepare a spherical alumina carrier with the diameter of 5 mm;

(2) mixing nitrate solutions of Co, Mo and Pd according to a specific ratio to prepare a catalyst impregnation solution, pre-impregnating an alumina carrier to obtain a wet-ball carrier, drying and roasting;

(3) cooling the catalyst precursor prepared in the step (2), soaking the catalyst precursor in the catalyst soaking solution prepared in the step (2), taking out the catalyst precursor, drying and roasting the catalyst precursor to obtain Co-Ni-Pd/Al₂O₃A catalyst.

Wherein:

the involved reaction equation is:

NaOH+Al(OH)₃＝NaAlO₂+H₂O

NaAlO₂+H₂O+HNO₃＝Al(OH)₃↓+NaNO₃。

and (2) adding a sodium hydroxide solution in the step (1), mixing for 1.5h, adding nitric acid for neutralization, and neutralizing for 35 min.

The aging temperature in the step (1) is 110 ℃, and the aging time is 3 h; washing with water; the drying temperature is 135 ℃, and the drying time is 5 hours; the roasting temperature is 350 ℃, and the roasting time is 4 hours.

The mass fraction of the cobalt nitrate solution in the step (2) is 15%; the mass fraction of the molybdenum nitrate solution is 5 percent; the mass fraction of the palladium nitrate solution is 20%.

The pre-impregnation time in the step (2) is 1.5 h.

And (4) cooling to 30 ℃ in the step (3), and impregnating again, wherein the impregnating time is 1.5 h.

And (3) adopting equal-volume impregnation when impregnating in the impregnation liquid in the step (2) and the step (3).

The drying and roasting process parameters in the step (2) and the step (3) are the same, the drying temperature is 135 ℃, and the drying time is 5 hours; the roasting temperature is 350 ℃, and the roasting time is 5 hours.

The detection shows that the isopropanolamine accounts for 48.03%, the 1, 2-propane diamine accounts for 47.67%, the water accounts for 2.07%, and the 2, 6-dimethyl piperazine accounts for 2.23%.

Comparative example 1

The method for producing isopropanolamine and 1, 2-propanediamine by cracking 2, 6-dimethylpiperazine in the comparative example 1 has the same process parameters as the method in the example 1, and has the only difference that the adopted catalyst is different, and Co-Mo/Al is adopted₂O₃Catalyst, said Co-Mo/Al₂O₃Catalyst, CoO is 3% of catalyst weight and MoO is 3% of catalyst weight based on metal oxide weight.

The detection shows that the isopropanolamine accounts for 38.99%, the 1, 2-propane diamine accounts for 39.32%, the water accounts for 3.34%, and the 2, 6-dimethyl piperazine accounts for 18.35%.

Comparative example 2

The method for producing isopropanolamine and 1, 2-propanediamine by cracking 2, 6-dimethylpiperazine in the comparative example 2 has the same process parameters as the method in the example 1, and has the only difference that the adopted catalyst is different, and Co-Pd/Al is adopted₂O₃Catalyst, said Co-Pd/Al₂O₃Catalyst, CoO is 3% of catalyst weight and PdO is 3% of catalyst weight according to metal oxide weight.

The detection shows that the isopropanolamine accounts for 33.47%, the 1, 2-propane diamine accounts for 34.56%, the water accounts for 4.69%, and the 2, 6-dimethyl piperazine accounts for 27.28%.

Comparative example 3

The method for producing isopropanolamine and 1, 2-propanediamine by cracking 2, 6-dimethylpiperazine, which is described in the comparative example 3, has the same process parameters as those of the example 1, and has the only difference that the catalyst is different and Mo-Pd/Al is adopted₂O₃Catalyst, said Mo-Pd/Al₂O₃The catalyst comprises MoO which accounts for 3% of the weight of the catalyst and PdO which accounts for 3% of the weight of the catalyst according to the weight of metal oxides.

The detection shows that the isopropanolamine accounts for 31.04%, the 1, 2-propane diamine accounts for 30.87%, the water accounts for 3.71%, and the 2, 6-dimethyl piperazine accounts for 34.38%.

Comparative example 4

The method for producing isopropanolamine and 1, 2-propanediamine by cracking 2, 6-dimethylpiperazine, which is described in the comparative example 4, has the same process parameters as those of the example 1, and has the only difference that the adopted catalyst is different, and Co-Mo-Ni/Al is adopted₂O₃Catalyst, said Co-Mo-Ni/Al₂O₃The catalyst comprises, by weight of metal oxides, 10% of CoO, 20% of NiO and 1.0% of MoO by weight of the catalyst.

The detection shows that the isopropanolamine accounts for 6.55%, the 1, 2-propane diamine accounts for 6.36%, the water accounts for 1.77%, and the 2, 6-dimethyl piperazine accounts for 85.32%.