Method for preparing adsorbent by using high-boiling-point byproduct in piperazine preparation process

Abstract

The invention relates to a method for preparing an adsorbent by using a high-boiling-point byproduct in a piperazine preparation process, and belongs to the field of reutilization of waste materials and byproduct materials, the method comprises the following steps: preheating a deactivated catalyst obtained after the reaction of preparing piperazine from ethylenediamine and co-producing triethylene diamine by using a reactor, and blowing until a low-boiling-point material adsorbed by the deactivated catalyst is blown off; the method comprises the following steps: adding a deactivated catalyst into a reaction kettle, cooling to room temperature to obtain a treated deactivated catalyst, taking a high-boiling-point byproduct in a reboiler for co-production of piperazine and triethylene diamine from ethylenediamine, adding a high-boiling-point polyethylene polyamine compound and the treated deactivated catalyst into the reaction kettle, adding water, heating, carrying out a constant-temperature reaction, cooling, discharging the material, and filtering to obtain the product. The aqueous solution is separated from the solid material, the solid material is dried under nitrogen protection, and the obtained solid material is used as an adsorbent. The adsorbent can be used as an adsorbent for acid gas, the deactivated catalyst and high-boiling-point byproducts generated in the piperazine preparation process are fully utilized, and certain economic significance is achieved.

Description

Technical Field

[0001] The invention relates to the field of recycling waste materials and by-product materials, and in particular to a method for preparing an adsorbent by utilizing high-boiling-point by-products in the process of preparing piperazine. Background Art

[0002] When synthesizing piperazine, ethylenediamine is used as a raw material to undergo a self-condensation reaction, and triethylenediamine can be produced as a by-product. The process is usually synthesized in one step by a gas phase method under normal pressure. The commonly used catalysts are zeolites or solid acid catalysts. The zeolite is commonly used as a ZSM-5 molecular sieve catalyst. Using K-ZSM-5 molecular sieve as a catalyst, the reaction temperature is 340°C, and after more than 3 hours of reaction under gas phase conditions, the conversion rate of ethylenediamine drops from 90% to 80%. Using H-type molecular sieve as a catalyst, the yield of piperazine is less than 40%, and the selectivity is less than 60%. Or using Cs-ZSM-5 molecular sieve as a catalyst, at 340°C, the vaporized diethylamine aqueous solution contacts the catalyst for reaction, the conversion rate of ethylenediamine is 55%, and the selectivity of generating piperazine is 55%, that is, this process will produce more by-products, and the reuse of by-products is also a big problem, among which about 3% of high-boiling point compounds will be produced. This compound is a polyethylene polyamine compound, which is miscible with water when it comes down from the reaction, and contains some impurities, which is difficult to use.

[0003] The catalyst used in the preparation of piperazine from ethylenediamine as a raw material can be a molecular sieve catalyst, which is formed by a molecular sieve and a binder. The binder is silica sol, aluminum sol, titanium sol, and pseudo-boehmite. When these materials are used as binders, they are calcined to form porous materials, which adsorb high-boiling point compounds in the reaction process together with the molecular sieve. After the catalyst is used for a period of time and adsorbs these high-boiling point compounds, the conversion rate of ethylenediamine and the selectivity of piperazine decrease, and it no longer has good technical and economic indicators, and the activity and selectivity decrease. It must be regenerated before it can be used again. The regeneration method of these deactivated catalysts mostly adopts the roasting method, and nitrogen oxides are formed during the roasting process, which pollutes the environment. Summary of the invention

[0004] According to the problem that the high boiling point by-products and deactivated catalysts of the reaction of preparing piperazine and co-producing triethylenediamine from ethylenediamine are difficult to handle at present, the purpose of the present invention is to provide a method for treating the high boiling point by-products and deactivated catalysts of the reaction of preparing piperazine and co-producing triethylenediamine from ethylenediamine, and to obtain a reusable adsorbent with good performance, which can be regenerated and reused, thereby reducing the pollution to the environment during the roasting and regeneration process.

[0005] The steps included in the present invention are as follows

[0006] The high boiling point by-product in the piperazine preparation process and the treated deactivated catalyst are mixed into a reactor, water is added, the temperature is raised to a certain temperature, and the adsorbent is reacted at a constant temperature;

[0007] Wherein, the deactivated catalyst is the deactivated catalyst obtained by the reaction of preparing piperazine from ethylenediamine and co-producing triethylenediamine;

[0008] The treatment process of the deactivated catalyst is as follows: the catalyst after the reaction of preparing piperazine from ethylenediamine and co-producing triethylenediamine is preheated in situ in a reactor to 340-370° C., nitrogen is introduced into the reactor to purge the low-boiling point materials adsorbed by the deactivated catalyst, and then the temperature is cooled to room temperature to obtain the treated deactivated catalyst;

[0009] The high boiling point by-product is a high boiling point by-product of the reaction of preparing piperazine from ethylenediamine and producing triethylenediamine;

[0010] The high boiling point by-product is an ethylene polyamine compound; common high boiling point by-products are diethylenetriamine, triethylenetetramine, and tetraethylenepentamine.

[0011] The deactivated catalyst can react and adsorb the high-boiling-point polyethylene polyamine compound again, so that the NH2-containing basic groups are enriched on the inner and outer surfaces of the catalyst, making it better suitable for the adsorption of acidic gases such as carbon dioxide.

[0012] After the high boiling point byproduct reacts with the deactivated catalyst at a constant temperature, the post-treatment process is as follows: the solid product is separated from water, and the solid product is dried in a certain atmosphere protection; the atmosphere is one of nitrogen, argon, and helium; the drying temperature is 50-80°C;

[0013] The active component of the deactivated catalyst is one or more of H-type, K-type, Ca-type, and Zn-type ZSM-5 molecular sieves, and the binder of the catalyst is one or more of silica sol, aluminum sol, titanium sol, pseudo-boehmite, and kaolin;

[0014] The addition ratio of the high boiling point byproduct to the deactivated catalyst is 0.2-0.5:1 (volume ratio), and the addition amount of water is 1.5-3 times of the total volume of the polyethylene polyamine compound and the catalyst.

[0015] The reaction temperature is 130-200°C and the reaction time is 2-6 hours.

[0016] The adsorbent prepared by the present invention can be used to adsorb acidic gases, and the acidic gases are one or more of carbon dioxide, hydrogen sulfide and sulfur dioxide gases.

[0017] The adsorbent generates water-soluble salts after adsorbing acidic gases. It is a reaction between weak acid and weak base and a reversible process. When the temperature is raised to 120-160°C, the reaction proceeds in reverse and the acidic gases can be released. When the temperature is raised above 120°C, the adsorbed CO2 can be desorbed. When the temperature is raised above 150°C, the adsorbed hydrogen sulfide can be desorbed, that is, the adsorbent can be reused.

[0018] The beneficial effects of the present invention are:

[0019] 1. The polyethylene polyamine compound, a byproduct of preparing piperazine using ethylenediamine as a raw material, has a high boiling point and is a mixture, so it cannot be reused. The present invention makes full use of this part of the high boiling point byproduct as an active point for adsorbing acidic gases;

[0020] 2. The deactivated catalyst for preparing piperazine from ethylenediamine as a raw material is heavily polluted because the carbon deposits are mostly N-containing compounds. Direct roasting and regeneration causes heavy pollution. The present invention utilizes the deactivated catalyst. The deactivated catalyst is not roasted at high temperature and does not produce ammonia-containing waste gas. Instead, the carbon deposits are purged with nitrogen to remove low-boiling point substances. The carbon deposits do not need to be treated and react with high-boiling point polyethylene polyamine compounds to obtain an adsorbent. The adsorbent can directly adsorb acidic gases and can be reused. DETAILED DESCRIPTION

[0021] The present invention will be further explained below by way of examples, but the present invention is not limited to these examples.

[0022] In the following examples, the deactivated catalyst is obtained from the deactivated catalyst obtained after the reaction of preparing piperazine from ethylenediamine and producing triethylenediamine is completed, and the high-boiling point by-product is taken from the reboiler of preparing piperazine from ethylenediamine and producing triethylenediamine.

[0023] The detection instrument involved in the embodiment is: gas chromatography-mass spectrometry: model 7890B-5977A.

[0024] Example 1

[0025] (1): The deactivated catalyst (active component is K-ZSM-5 molecular sieve, and the binder is silica sol and kaolin) is preheated to 350° C. in a reactor, and nitrogen is introduced into the reactor in an amount such that low-boiling-point materials adsorbed by the deactivated catalyst are blown off, and then cooled to room temperature to obtain a treated deactivated catalyst;

[0026] (2) Take a high boiling point compound (analyzed by gas chromatography-mass spectrometry to show that the content of diethylenetriamine is 31%, triethylenetetramine is 49%, and tetraethylenepentamine is 18%), put the high boiling point polyethylene polyamine compound and the deactivated catalyst treated in step (1) into a reactor, add the polyethylene polyamine compound: catalyst = 0.5:1 (volume ratio), add water in an amount twice the total volume of the polyethylene polyamine compound and the catalyst, raise the temperature to 200°C, react at a constant temperature for 5 hours, cool down, unload the material, separate the aqueous solution from the solid material, dry the solid material at 60°C under nitrogen protection, and use the obtained solid material as an adsorbent.

[0027] Example 2

[0028] (1): The deactivated catalyst (active component is K-ZSM-5 molecular sieve, and the binder is silica sol and kaolin) is preheated to 360° C. in a reactor, and nitrogen is introduced into the reactor in an amount such that low-boiling-point materials adsorbed by the deactivated catalyst are blown off, and then cooled to room temperature to obtain a treated deactivated catalyst;

[0029] (2) Take a high boiling point compound (analyzed by gas chromatography-mass spectrometry to have a content of 25% diethylenetriamine, 48% triethylenetetramine, and 25% tetraethylenepentamine), put the high boiling point polyethylene polyamine compound and the deactivated catalyst treated in step (1) into a reactor, add the polyethylene polyamine compound: catalyst = 0.4:1 (volume ratio), add 2.5 times the total volume of the polyethylene polyamine compound and the catalyst, heat to 160°C, react at a constant temperature for 5 hours, cool down, unload the material, separate the aqueous solution and the solid material, dry the solid material at 70°C under nitrogen protection, and use the obtained solid material as an adsorbent.

[0030] Example 3

[0031] (1): The deactivated catalyst (active component is Ca-ZSM-5 molecular sieve, and the binder is silica sol) is preheated to 360° C. in a reactor, and nitrogen is introduced into the reactor in an amount sufficient to purge the low-boiling point materials adsorbed by the deactivated catalyst, and then cooled to room temperature to obtain a treated deactivated catalyst;

[0032] (2) Take a high boiling point compound (analyzed by gas chromatography-mass spectrometry to have a content of 26% diethylenetriamine, 49% triethylenetetramine and 18% tetraethylenepentamine), put the high boiling point polyethylene polyamine compound and the deactivated catalyst treated in step (1) into a reactor, add the polyethylene polyamine compound: catalyst = 0.3:1 (volume ratio), add water in an amount twice the total volume of the polyethylene polyamine compound and the catalyst, raise the temperature to 170°C, react at a constant temperature for 4 hours, cool down, unload the material, separate the aqueous solution from the solid material, dry the solid material at 60°C under nitrogen protection, and use the obtained solid material as an adsorbent.

[0033] Example 4

[0034] Adsorbent evaluation

[0035] The fixed bed was used for evaluation. The adsorbent was crushed and sieved to 40-60 mesh. The filling amount was 2g. CO2 gas (CO2 volume percentage 10%, N2 balance) was introduced at a flow rate of 100mL / min for carbon dioxide adsorption. After the carbon dioxide adsorption was saturated, the reactor was heated to 120°C to regenerate the adsorbent, and then CO2 gas was introduced for adsorption again.

[0036] The saturated adsorption capacity of the adsorbents in Examples 1-3 and the adsorption attenuation after 5 times are shown in Table 1

[0037] Example Carbon dioxide saturation adsorption capacity (g / g) Adsorption attenuation after 5 times (%) Example 1 0.15 21％ Example 2 0.18 17％ Example 3 0.17 18％

[0038] 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 preparing an adsorbent using a high boiling point by-product in the process of preparing piperazine, characterized in that The following steps are involved: The high boiling point byproducts in the piperazine preparation process and the treated deactivated catalyst are mixed into a reactor, water is added, the temperature is raised to a certain temperature, the reaction is carried out at a constant temperature, and then post-processing is performed to obtain an adsorbent; Wherein, the deactivated catalyst is the deactivated catalyst obtained by the reaction of preparing piperazine from ethylenediamine and co-producing triethylenediamine; The high boiling point by-product is a high boiling point by-product of the reaction of preparing piperazine from ethylenediamine and co-producing triethylenediamine.

2. The method for preparing an adsorbent using a high boiling point by-product in the piperazine preparation process according to claim 1, characterized in that: The deactivated catalyst treatment process is as follows: the catalyst after the reaction of preparing piperazine from ethylenediamine and co-producing triethylenediamine is preheated in situ to 340-370° C. in a reactor, nitrogen is introduced into the reactor to blow away the low-boiling point materials adsorbed by the deactivated catalyst, and then cooled to room temperature to obtain the treated deactivated catalyst.

3. The method for preparing an adsorbent using a high boiling point by-product in the piperazine preparation process according to claim 1, characterized in that The high boiling point by-product is a polyethylene polyamine compound.

4. The method for preparing an adsorbent using a high boiling point by-product in the piperazine preparation process according to claim 1, characterized in that: After the high boiling point by-products react with the treated deactivated catalyst at a constant temperature, the post-treatment process is as follows: the solid product is separated from water, and the solid product is dried in a certain atmosphere protection.

5. The method for preparing an adsorbent using a high boiling point by-product in the piperazine preparation process according to claim 4, characterized in that The atmosphere is one of nitrogen, argon and helium.

6. The method for preparing an adsorbent using a high boiling point by-product in the piperazine preparation process according to claim 4, characterized in that The drying temperature is 50-80°C.

7. The method for preparing an adsorbent using a high boiling point by-product in the piperazine preparation process according to claim 1, characterized in that The active component of the deactivated catalyst is one or more of H-type, K-type, Ca-type and Zn-type ZSM-5 molecular sieves.

8. The method for preparing an adsorbent using a high boiling point by-product in the piperazine preparation process according to claim 1, characterized in that The volume ratio of the high boiling point byproduct to the deactivated catalyst is 0.2-0.5:1, and the amount of water added is 1.5-3 times the total volume of the polyethylene polyamine compound and the catalyst.

9. The method for preparing an adsorbent using a high boiling point by-product in the piperazine preparation process according to claim 1, characterized in that The reaction temperature is 130-200°C and the reaction time is 2-6 hours.

10. The adsorbent prepared by the method for preparing an adsorbent using a high boiling point by-product in the process of preparing piperazine according to claims 1-9, characterized in that The adsorbent is used to adsorb acidic gases, which are one or more of carbon dioxide, hydrogen sulfide, and sulfur dioxide.