Method for adjusting reaction yield in preparation of piperazine and triethylene diamine from ethylenediamine

Abstract

The invention relates to a method for adjusting the reaction yield of piperazine and triethylene diamine prepared from ethylenediamine, which comprises the following steps: taking an ethylenediamine aqueous solution as a raw material, taking a ZSM-5 molecular sieve as a spherical catalyst of an active center, taking a fixed bed reactor as a reactor, reacting at the temperature of 300-360 DEG C at the mass space velocity of 0.1-4h <-1 >, inert ceramic balls or ceramic rings with the height of 0.5 m are placed below the catalyst bed layer, the ceramic balls or ceramic rings are composed of alpha-phase aluminum oxide, an auxiliary agent is added in the raw material feeding process, the auxiliary agent is one or a mixture of more of potassium hydroxide, calcium hydroxide, strontium hydroxide, sodium aluminate and potassium aluminate, and the raw material feeding process is completed; the yields of piperazine and triethylene diamine products are adjusted by adjusting the addition amount of the auxiliary agent, the reaction temperature and the feeding mass space velocity of the raw materials, and the adjustment range of the reaction product piperazine to triethylene diamine is 1: (0.2-0.9). According to the method disclosed by the invention, the yield of piperazine and triethylene diamine can be adjusted according to industrial production and market demand conditions.

Description

Technical Field

[0001] The invention relates to a method for preparing piperazine and triethylenediamine from ethylenediamine, and in particular to a method for adjusting the reaction yield of preparing piperazine and triethylenediamine from ethylenediamine. Background Art

[0002] At present, the process of synthesizing piperazine and producing triethylenediamine as a by-product is mainly a multiphase catalytic method, and the main processes are the ethylene dichloride method, the ethylenediamine method, and the ethanolamine method. In addition to the low reaction efficiency of the ethylene dichloride production process, the complex subsequent treatment, and the serious pollution, the ethanolamine method is also the research direction of many units.

[0003] Using ethylenediamine as raw material for self-condensation can generate piperazine and co-produce high-value triethylenediamine. The reaction is a normal pressure gas-solid phase reaction. Different catalysts are used in this process, and the reaction product results are also different. The catalysts used in the ethylenediamine self-condensation method mainly include molecular sieves, composite metals, metal phosphates, etc. for catalytic reactions. The spherical catalyst with the active center of ZSM-5 molecular sieve is a commonly used catalyst for the ethylenediamine self-condensation method. The catalyst usually needs to be modified to improve its activity and selectivity, so that it is more suitable for the industrial production of piperazine and triethylenediamine. In the gas-phase catalytic conversion of ethylenediamine, piperazine can be generated on the weak acid center, and the medium-strong acid center is more conducive to the selective generation of triethylenediamine.

[0004] In recent years, with the gradual release of new domestic ethylenediamine production capacity, the tight supply and demand situation of ethylenediamine will be greatly improved. Since the demand for piperazine and triethylenediamine in the market also fluctuates greatly, for example, part of the market for triethylenediamine will be replaced by polyethylene polyamine compounds from other sources. This requires production units to be able to significantly adjust the output of piperazine and triethylenediamine according to changes in market demand in order to maximize operating benefits. Summary of the invention

[0005] In view of the problems existing in current industrial production, the purpose of the present invention is as follows:

[0006] (1) One of the objects of the present invention is to provide a method for adjusting the yield of the reaction of preparing piperazine and triethylenediamine from ethylenediamine;

[0007] (2) The second object of the present invention is that the adjustment method of the present invention can be operated without disassembling the reactor, and the product ratio can be adjusted in situ to meet market demand and increase economic benefits. The yield of piperazine and triethylenediamine can be adjusted over a wide range during the production process.

[0008] The technical solution adopted by the present invention is as follows:

[0009] The reaction of preparing piperazine and triethylenediamine from ethylenediamine of the present invention uses ethylenediamine aqueous solution as raw material (mass fraction 40-60%), ZSM-5 molecular sieve as spherical catalyst with active center, and the reactor is a fixed bed reactor. Inert ceramic balls or ceramic rings with the same height as the catalyst are placed under the catalyst bed, and the composition of the ceramic balls or ceramic rings is alpha-phase aluminum oxide.

[0010] An auxiliary agent is added to the raw material feed of the reaction of preparing piperazine and triethylenediamine from ethylenediamine. The yield of the product piperazine and triethylenediamine can be adjusted by adjusting the amount of the auxiliary agent added. The adjustment range of the reaction product is piperazine: triethylenediamine = 1:0.2-0.9 (molar ratio).

[0011] The auxiliary agent is a mixture of one or more of potassium hydroxide, calcium hydroxide, strontium hydroxide, sodium aluminate and potassium aluminate;

[0012] It should be noted here that alkali metals are added to the reaction raw materials, enter the reactor, diffuse in the reactor with water vapor, act on the catalyst, and adjust the acidity of the catalyst. In addition, when the auxiliary agent is sodium aluminate or potassium aluminate, adding aluminum elements at the same time can improve the performance attenuation caused by the removal of framework aluminum when the molecular sieve is used in a high-temperature water vapor environment.

[0013] The amount of additive added per hour is 0.001-0.08% of the mass of the catalyst. The addition of additives can significantly adjust the acidity of the inner and outer surfaces of the catalyst during use, and lead to changes in activity. When more piperazine needs to be produced, the reaction temperature is lowered, the space velocity is increased, and the amount of additive added is increased; when more triethylenediamine needs to be produced, the reaction temperature is increased, the space velocity is reduced, and the amount of additive added is reduced.

[0014] The selected mass airspeed range is: 0.1-4h -1 .

[0015] The selected reaction temperature range is: 300-360°C.

[0016] When the piperazine yield needs to be increased, the hourly addition amount of the auxiliary agent can be increased, the mass space velocity can be increased, and the reaction temperature can be lowered. The adjustment range is: the hourly addition amount of the auxiliary agent is 0.01 to 0.08% of the mass of the catalyst, and the mass space velocity selection range is: 1 to 4h -1 , the reaction temperature selection range is: 330 to 300℃.

[0017] When the yield of triethylenediamine needs to be increased, the amount of additive added per hour is reduced, the mass space velocity is reduced, and the reaction temperature is increased. Adjustment range: The amount of additive added per hour is 0.01% to 0.001% of the mass of the catalyst, and the mass space velocity selection range is: 1 to 0.1h -1 , the reaction temperature selection range is: 330 to 360℃.

[0018] The above two auxiliary agents, space velocity, and reaction temperature range only represent a trend for obtaining a high yield of piperazine or triethylenediamine. The overlapping reaction conditions can be regarded as the starting point or dividing point for adjusting the yield.

[0019] Specifically, the ZSM-5 molecular sieve catalyst used is a commercially available molecular sieve with a silicon-aluminum ratio of 20-80, and is used after being pelletized.

[0020] The invention adds an auxiliary agent to the raw material and can adjust the yield of the product according to the product quantity demand. By increasing the amount of the auxiliary agent added, the space velocity is increased, and the yield of piperazine is improved. By reducing the amount of the auxiliary agent added, the space velocity is reduced, and the yield of triethylenediamine is improved.

[0021] The present invention can be implemented in the same device without replacing the catalyst, and can directly change the product yield to meet market demand. DETAILED DESCRIPTION

[0022] Specific implementation modes are given below in combination with the present invention, but are not limited to the present invention.

[0023] The molecular sieve catalyst used in the embodiment is a commercially available ZSM-5 molecular sieve, and different silicon-to-aluminum ratios are selected according to needs, and the silicon-to-aluminum ratio range is 20-80.

[0024] Example 1

[0025] Ethylenediamine aqueous solution was used as raw material (mass fraction 40%), ZSM-5 molecular sieve (silicon-aluminum ratio 60) was used as catalyst, the reactor was a fixed bed reactor, the reaction temperature was 350°C, and the space velocity was 2h -1 , inert ceramic balls of the same height as the catalyst were placed under the catalyst bed, and no additives were added to the raw material feed. The raw material conversion rate and product selectivity are shown in Table 1.

[0026] Example 2

[0027] Other experimental conditions were consistent with those in Example 1. Auxiliary agent: potassium hydroxide was added to the feed in an amount of 0.05% of the mass of the catalyst per hour. The space velocity was unchanged. The reaction temperature was 330° C. The feed conversion rate and product selectivity were shown in Table 1. The output ratio of piperazine to triethylenediamine was 1:0.21.

[0028] Example 3

[0029] Other experimental conditions were consistent with those in Example 1. Auxiliary agent: potassium hydroxide was added to the feed at an amount of 0.005% of the mass of the catalyst per hour. The space velocity was adjusted to 0.5 h -1 , the reaction temperature remains unchanged. The raw material conversion rate and product selectivity are shown in Table 1, and the output ratio of piperazine: triethylenediamine is 1:0.69.

[0030] Example 4

[0031] Ethylenediamine aqueous solution was used as raw material (mass fraction 45%), ZSM-5 molecular sieve (silicon-aluminum ratio 40) was used as catalyst, the reactor was a fixed bed reactor, the reaction temperature was 350°C, and the space velocity was 2h -1 , inert ceramic balls of the same height as the catalyst were placed under the catalyst bed, no additives were added to the raw material feed, and the yields of piperazine and triethylenediamine. The raw material conversion rate and product selectivity are shown in Table 1.

[0032] Example 5

[0033] Other test conditions were consistent with those in Example 4. An auxiliary agent, sodium aluminate, was added to the feed at an amount of 0.03% of the mass of the catalyst per hour. The space velocity remained unchanged. The reaction temperature was adjusted to 320° C. The feed conversion rate and product selectivity are shown in Table 1. The output ratio of piperazine to triethylenediamine was 1:0.31.

[0034] Example 6

[0035] Other test conditions were consistent with those in Example 4. Auxiliary agent: sodium aluminate was added to the feed at an amount of 0.008% of the mass of the catalyst per hour. The air velocity was adjusted to 0.5 h -1 , the reaction temperature remained unchanged, the raw material conversion rate and product selectivity were shown in Table 1, and the output ratio of piperazine: triethylenediamine was 1:0.71.

[0036] Product yield of each example = conversion rate * selectivity

[0037] The calculation method of output ratio is = yield 哌嗪 / Yield 三乙烯二胺 =Selectivity 哌嗪 / Selective 三乙烯二胺

[0038] Table 1 Example product performance

[0039] Conversion rate of ethylenediamine / % Piperazine selectivity / % Triethylenediamine selectivity / % Example 1 70％ 56％ 12％ Example 2 98％ 81％ 17％ Example 3 95％ 58％ 40％ Example 4 68％ 52％ 15％ Example 5 96％ 75％ 23％ Example 6 94％ 56％ 40％

[0040] The applicant declares that the present invention illustrates the detailed process flow of the present invention through the above-mentioned embodiments, but the present invention is not limited to the above-mentioned detailed process flow, that is, it does not mean that the present invention must rely on the above-mentioned detailed process flow to be implemented. Those skilled in the art should understand that any improvement of the present invention, equivalent replacement of various raw materials of the product of the present invention, addition of auxiliary components, selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

Claims

1. A method for adjusting the yield of the reaction of ethylenediamine to prepare piperazine and triethylenediamine, characterized in that The following steps are involved: An auxiliary agent is added to the raw material feed of the reaction of preparing piperazine and triethylenediamine from ethylenediamine. The yield of the product piperazine and triethylenediamine can be adjusted by adjusting the amount of the auxiliary agent added. The adjustment range of the reaction product is piperazine:triethylenediamine molar ratio = 1:0.2-0.

9.

2. The method for adjusting the reaction yield of ethylenediamine to prepare piperazine and triethylenediamine according to claim 1, characterized in that The auxiliary agent is a mixture of one or more of potassium hydroxide, calcium hydroxide, strontium hydroxide, sodium aluminate and potassium aluminate.

3. The method for adjusting the reaction yield of ethylenediamine to prepare piperazine and triethylenediamine according to claim 1, characterized in that The amount of the auxiliary agent added per hour is 0.001-0.08% of the mass of the catalyst.

4. The method for adjusting the reaction yield of ethylenediamine to prepare piperazine and triethylenediamine according to claim 1, characterized in that Mass airspeed range: 0.1-4h -1 .

5. The method for adjusting the reaction yield of ethylenediamine to prepare piperazine and triethylenediamine according to claim 1, characterized in that The reaction temperature range is: 300-360℃.

6. The method for adjusting the reaction yield of ethylenediamine to prepare piperazine and triethylenediamine according to claim 1, characterized in that The catalyst is a spherical catalyst with ZSM-5 molecular sieve as the active center, ethylenediamine aqueous solution is used as the raw material, and the reactor is a fixed bed reactor.