Carbamate extracting agent for removing alpha-olefin oxygen-containing compound and preparation method of carbamate extracting agent

Abstract

The invention relates to the field of fine chemical engineering separation technologies and new materials, in particular to a carbamate extracting agent for removing alpha-olefin oxygen-containing compounds and a preparation method thereof.The carbamate extracting agent is prepared by reacting propylene carbonate with excessive primary / secondary amine at the temperature of 20-120 DEG C for 1-10 hours and removing the excessive amine through reduced pressure distillation, and the structure of the carbamate extracting agent conforms to R3N-R1-NH-COO-R2; when the carbamate extracting agent is used, the carbamate extracting agent and impurity-containing alpha-olefin are subjected to liquid-liquid extraction at the temperature of 10-60 DEG C according to the mass ratio of 1: 20 to 1: 5, and the extracting agent can be washed and regenerated. The carbamate extracting agent for removing the alpha-olefin oxygen-containing compounds can remove aldehydes and aldehyde ketone oxygen-containing compounds in the alpha-olefin to be smaller than or equal to 1 ppm, meets the polymer grade requirement, is low in energy consumption, can be continuously operated, and is suitable for industrial production. And the method is green and environment-friendly and is easy for industrial production.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of fine chemical separation technology and new materials, and particularly relates to a carbamate extractant for removing alpha-olefin oxygen-containing compounds and a preparation method thereof. BACKGROUND

[0002] Alpha-olefins, such as 1-hexene and 1-octene, are important comonomers for producing high-density polyethylene (HDPE) and linear low-density polyethylene (LLDPE), and the purity of the alpha-olefins directly affects the performance of the polyolefin products. In the production process of alpha-olefins, trace amounts of oxygen-containing compound impurities, such as n-butyraldehyde and pentanal, are introduced. Even if the impurities are at the ppm level, they can seriously poison the subsequent Ziegler-Natta polymerization catalyst, resulting in catalyst deactivation, broadening of the molecular weight distribution of the polymer, and degradation of the product quality. The impurity control requirements for polymerization-grade alpha-olefins in Europe and the United States are usually below 1 ppm. It has been reported that aldehyde impurities can cause the catalyst activity to decrease by more than 80%, which seriously affects the polymerization efficiency.

[0003] The current common removal techniques for oxygen-containing compounds in alpha-olefins have obvious defects and deficiencies: the rectification method has high energy consumption and is difficult to separate oxygen-containing compound impurities with boiling points close to those of alpha-olefins, and the removal efficiency can only reach about 20 ppm, which cannot meet the deep purification requirements; the molecular sieve adsorption method has limited adsorption capacity and needs to be regenerated frequently by burning, which is discontinuous in operation, and the removal effect is about 15 ppm, which is difficult to adapt to industrial continuous production; conventional solvent extraction methods, such as the use of propylene carbonate (PC) and dimethyl carbonate (DMC), have a removal efficiency of about 18 ppm for unmodified PC and about 52 ppm for DMC, both of which have the problem of insufficient selectivity and cannot meet the deep purification requirements of <1 ppm to adapt to high-end polymerization processes. Although propylene carbonate is a green and highly polar solvent and has certain solubility for some oxygen-containing compounds, the extraction selectivity and capacity of unmodified PC for oxygen-containing compounds are still limited, especially for deep removal (requirements below 10 ppm, even 1 ppm) to meet the needs of high-end polymerization. The fundamental reason is that PC molecules themselves lack active sites for specific and strong interactions with target impurities (such as the carbonyl groups of aldehydes and ketones). Therefore, in view of the above status, it is urgent to develop a carbamate extractant for removing alpha-olefin oxygen-containing compounds and a preparation method thereof to overcome the deficiencies in current practical applications. SUMMARY

[0004] The present application aims to provide a carbamate extractant for removing alpha-olefin oxygen-containing compounds and a preparation method thereof to solve the problems raised in the background.

[0005] To achieve the above-mentioned purpose, the present application provides the following technical solutions: A carbamate extractant for removing alpha-olefin oxygen-containing compounds, the structure of the extractant conforms to general formula (I): R 3 N-R 1 -NH-COO-R 2 ; Wherein, R 1 is a carbon chain (such as alkylene) connecting the carbamate group, R 2 is a substituent of the ester group (usually derived from an alcohol or cyclic carbonate), and R 3 is a substituent (such as hydrogen, alkyl or aryl) connecting the nitrogen atom (secondary amino group).

[0006] As a further scheme of the present application: the R 2 is -CH(CH3)CH2OH or -CH2CH(CH3)OH.

[0007] As a further scheme of the present application: the R 1 is one of -CH2CH2- and -CH2CH2CH2-.

[0008] As a further scheme of the present application: the R 3 is one of hydrogen, alkyl or aryl.

[0009] As a further scheme of the present application: the extractant is 1-(2-aminoethyl carbamoyloxy)-2-propanol.

[0010] As a further scheme of the present application: the molecule of the extractant contains at least one primary amino group and one hydroxyl group.

[0011] A method for preparing the above-mentioned carbamate extractant for removing alpha-olefin oxygen-containing compounds, comprising the following steps: reacting propylene carbonate with an excess of primary or secondary amine at a certain temperature for a certain time, and then removing the excess of primary or secondary amine by vacuum distillation to obtain the carbamate extractant.

[0012] As a further scheme of the present application: the molar ratio of propylene carbonate to primary or secondary amine is 1:2-1:5.

[0013] As a further scheme of the present application: the temperature is 20-120℃, and the time is 1-10 hours.

[0014] The application of the above-mentioned carbamate extractant for removing alpha-olefin oxygen-containing compounds in removing alpha-olefin oxygen-containing compounds, the oxygen-containing compounds are aldehydes or ketones, and the residual concentration of alpha-olefin oxygen-containing compounds after removal is ≤1 ppm.

[0015] As a further scheme of the present application: the application comprises: mixing the extractant with the impurity-containing alpha-olefin at a mass ratio of 1:20-1:5, carrying out liquid-liquid extraction at 10-60 DEG C, and collecting the upper layer refined alpha-olefin after standing and layering.

[0016] Compared with the prior art, the present application has the beneficial effects that: The present application realizes the leap from "physical dissolution" to "chemical recognition" by ring-opening modification of propylene carbonate (PC) and directional introduction of amino groups (especially primary amino groups) capable of specific action with carbonyl groups, and the selectivity for aldehyde and ketone impurities is qualitatively improved; due to the strong interaction, the extractant of the present application can easily remove the content of aldehydes and ketones in alpha-olefin from 10 ppm to below 1 ppm, meeting the most stringent polymerization grade requirements, and for n-butyraldehyde with an initial content of 100 ppm, the content can be removed to 0.3 ppm, and the purification efficiency is more than 99.7%, which is difficult to achieve by physical extraction method; The amino groups in the extractant molecule have strong interaction with various oxygen-containing compounds (such as aldehydes and ketones), have good universality, and also exhibit excellent separation effect on alpha-olefins with different carbon numbers (such as 1-butene, 1-hexene and 1-octene), and can reduce the content of aldehydes in 1-butene and 1-octene to 0.5 ppm and 0.2 ppm respectively, and the application range is wide; After the extraction is completed, the extractant has moderate water solubility due to the presence of hydroxyl groups, and the extractant enriched with impurities can be regenerated by a very simple and inexpensive water washing method, avoiding high energy consumption caused by rectification regeneration, and the process flow is simple and the operation cost is greatly reduced; the performance of the regenerated extractant is attenuated very little (<5%), and can be used repeatedly, meeting the requirements of green chemical industry and circular economy, and having high industrial application value; The present application takes the recognized green solvent propylene carbonate (PC) as the starting point for synthesis, has high atom economy; the synthesis route is completed in one step, the conditions are mild (medium temperature, normal pressure), and no noble metal catalyst or strong corrosive reagent is needed, and the production process is safe and controllable; the final product inherits the characteristics of low toxicity and biodegradability of PC, and the whole process from synthesis, use to regeneration is environmentally friendly; The molecular structure of the extractant of the present application is clear, the synthesis path is clear (ring-opening addition reaction of amine to cyclic carbonate), the reaction efficiency is high, and the yield can be more than 95%; the preparation process does not need complex equipment, the post-treatment is simple, and it is very beneficial to large-scale production, and the technical transformation is feasible. BRIEF DESCRIPTION OF DRAWINGS

[0017] Figure 1 It is a synthesis route diagram of the extractant (taking the product modified by ethylenediamine as an example) in the embodiments of the present application.

[0018] Figure 2 The extraction and refining process flow chart in the embodiment of the present application.

[0019] Figure 3 The extraction and refining process flow chart in the embodiment of the present application.

[0020] Figure 4 The nuclear magnetic resonance hydrogen spectrum (H NMR) chart of the extractant A in the embodiment 1 of the present application. 1 The test solvent is CDCl3.

[0021] Figure 5 The infrared spectrum (FT-IR) chart of the extractant A in the embodiment 1 of the present application. The key characteristic absorption peaks in the spectrum include: the wide absorption peak at ~3400 cm -1 belongs to the stretching vibration of the hydroxyl (-OH) and the primary amino group (-N-H) in the molecule; the strong absorption peak at ~1650 cm -1 belongs to the stretching vibration of the carbamate carbonyl (C=O); the absorption peak at ~1100 cm -1 belongs to the stretching vibration of the C-O bond; and the above characteristic peaks jointly prove that the product has the target carbamate structure (HO-R 1 -NH-COO-R 2 ). DETAILED DESCRIPTION

[0022] The technical solutions in the embodiments of the present application will be described clearly and completely in combination with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, but not all the embodiments. Based on the embodiments in the present application, all the other embodiments obtained by those skilled in the art without creative labor fall within the protection scope of the present application.

[0023] The specific implementation of the present application will be described in detail in combination with specific embodiments.

[0024] Please refer to Figures 1-5 , the present application provides a kind of carbamate extractant for removing α-olefin oxygen-containing compound and its preparation method, specific content as follows: (1) provide carbamate functionalized extractant, the structure of the extractant meets general formula (I): HO-R 1 -NH-COO-R 2 (I), wherein R 1 It is C2-C6 straight-chain or branched alkylene group, derived from amine-containing compound, R 2The 1,2-propanediol residue is derived from the ring opening of propylene carbonate, and the extractant molecule contains at least one primary amino group and one hydroxyl group; (2) A preparation method of the extractant is provided, which uses propylene carbonate and an excess of a primary amine or a secondary amine as raw materials, reacts at 20-120°C for 1-10 hours, and then removes the excess amine by distillation under reduced pressure to obtain the target extractant; (3) The application of the extractant is provided, which is mixed with impurity-containing α-olefins at a mass ratio of 1:20 to 1:5, liquid-liquid extraction is carried out at 10-60°C, and after standing and layering, the upper layer is refined α-olefins, and the used extractant can be regenerated by water washing and recycled.

[0025] The application will be further described in detail below in combination with the accompanying drawings and specific examples, and the protection scope of the application is not limited to the following examples.

[0026] I. Synthesis of functionalized extractant Example 1: Synthesis of extractant A (1-(2-aminoethylcarbamoyloxy)-2-propanol) A 250 mL three-necked round-bottom flask equipped with a magnetic stirrer, a reflux condenser and a thermometer was charged with 105 g of analytical grade anhydrous ethylenediamine. The reaction system was cooled in an ice water bath and stirred, and 52 g of propylene carbonate (PC) was slowly added dropwise through a constant pressure dropping funnel, and the dropping speed was controlled to maintain the reaction temperature below 30°C to prevent the reaction from being too violent.

[0027] After the dropwise addition was completed, the ice water bath was removed, and the temperature of the oil bath was raised to 80°C, and the stirring was continued at this temperature for 4 hours. After the reaction was completed, the reaction liquid was transferred to a rotary evaporator, and the excess ethylenediamine was distilled off under the conditions of an 80°C water bath and a reduced pressure of -0.095 MPa to obtain a colorless to light yellow viscous liquid product.

[0028] In this example, 89.5 g of product was finally obtained, with a yield of 95% based on propylene carbonate. The product was characterized by infrared spectroscopy (FT-IR) and nuclear magnetic resonance hydrogen spectrum (HNMR) to confirm that its structure was 1-(2-aminoethylcarbamoyloxy)-2-propanol, which contained a primary amino group, a hydroxyl group and a carbamic acid ester bond, laying a structural foundation for subsequent deep removal of oxygen-containing compounds. 1 HNMR) to confirm that its structure was 1-(2-aminoethylcarbamoyloxy)-2-propanol, which contained a primary amino group, a hydroxyl group and a carbamic acid ester bond, laying a structural foundation for subsequent deep removal of oxygen-containing compounds.

[0029] Example 2: Synthesis of extractant B (1-(2-hydroxyethylcarbamoyloxy)-2-propanol) Into a 250 mL three-necked round bottom flask equipped with a magnetic stirrer, a reflux condenser and a thermometer, 61 grams (1.0 mol) of ethanolamine was charged. With stirring at room temperature, 52 grams (0.5 mol) of propylene carbonate was added dropwise. After the addition was completed, the reaction system was heated to 90°C and stirred for 5 hours. After the reaction was completed, unreacted ethanolamine was removed by distillation at 90°C under reduced pressure of -0.095 MPa to obtain a yellowish viscous liquid product.

[0030] In this example, about 85 grams of product was finally obtained with a yield of about 90%, which was characterized by infrared spectroscopy (FT-IR) and nuclear magnetic resonance hydrogen spectrum (HNMR) to confirm that it was the target product 1-(2-hydroxyethylaminocarbamoyloxy)-2-propanol. The product also had the core structure of primary amino, hydroxyl and carbamate bond and could be used for the removal of oxygen-containing compounds in α-olefins. 1 HNMR) to confirm that it was the target product 1-(2-hydroxyethylaminocarbamoyloxy)-2-propanol. The product also had the core structure of primary amino, hydroxyl and carbamate bond and could be used for the removal of oxygen-containing compounds in α-olefins.

[0031] II. Performance evaluation of the extractant Example 3: Performance evaluation of extractant A for the removal of n-butyraldehyde in 1-hexene Simulation of raw material preparation: Chromatographically pure 1-hexene was taken and accurately weighed n-butyraldehyde was added to prepare a simulated raw material oil with a n-butyraldehyde content of (102±2) ppm (weight ratio), which simulated the impurity content of α-olefins in industrial production.

[0032] Extraction experiment: Under constant temperature conditions at 25°C, 50 grams of the above-mentioned simulated raw material oil was accurately measured in a 125 mL separatory funnel, and 5 grams of the extractant A prepared in Example 1 was added, with a solvent / oil mass ratio of 1:10. The separatory funnel was sealed, manually shaken vigorously for 10 minutes, and then placed in a constant temperature rack for 30 minutes to allow it to fully separate.

[0033] Sample analysis: After standing and separating, the upper oil phase (refined 1-hexene) was carefully collected, and a gas chromatograph (GC) equipped with an FID detector was used to analyze the residual content of n-butyraldehyde in the upper oil phase under chromatographic conditions of a DB-WAX capillary column and programmed temperature.

[0034] In this example, the GC analysis results showed that the n-butyraldehyde content in the refined 1-hexene was 0.3 ppm, with a removal rate of 99.7%, achieving the goal of deeply removing oxygen-containing compounds in α-olefins to below 1 ppm, meeting the stringent requirements of high-end polymerization processes for raw material purity, and far superior to the removal effect of existing conventional solvents.

[0035] Comparative Example 1: Extraction performance of unmodified propylene carbonate (PC) The rest of the experimental steps, conditions (raw materials, solvent to oil ratio, temperature, time and analysis method) are exactly the same as Example 3, except that the extractant is replaced by an equal mass (5 g) of unmodified propylene carbonate (PC).

[0036] In this comparative example, the content of n-butyraldehyde in the refined 1-hexene is 18.5 ppm, and the removal rate is 81.9%. The results show that although the unmodified PC has a certain removal effect, it lacks active sites specific to oxygen-containing compounds, and the deep purification capacity is far inferior to the functionalized extractant A prepared by the present application.

[0037] Comparative Example 2: Extraction performance of dimethyl carbonate (DMC) The rest of the experimental conditions are exactly the same as Example 3, except that the extractant is replaced by an equal mass (5 g) of dimethyl carbonate (DMC).

[0038] In this comparative example, the content of n-butyraldehyde in the refined 1-hexene is 52.1 ppm, and the removal rate is only 48.9%. This further confirms the necessity of introducing specific active groups by chemical modification of PC in the present application, as well as the outstanding selectivity and removal efficiency of the functionalized extractant.

[0039] Comparative Example 3: Extraction performance of ethanolamine The rest of the experimental conditions are exactly the same as Example 3, except that the extractant is replaced by an equal mass (5 g) of ethanolamine.

[0040] In this comparative example, the content of n-butyraldehyde in the refined 1-hexene is 5.8 ppm, and the removal rate is 94.3%. Although ethanolamine itself has a certain removal effect, it has the problems of extremely high viscosity, which makes it difficult to separate from 1-hexene and has low mass transfer efficiency, and infinite mutual solubility with water, which leads to a large amount of extractant loss during the regeneration process, making it difficult to achieve industrial cyclic application. The product A of the present application has better physical properties while maintaining high activity, and is easy to operate and recover.

[0041] Example 4: Regeneration and cyclic use performance of extractant A The lower phase of the extractant A used in Example 3, which has been enriched with n-butyraldehyde, is collected, and an equal mass (5 g) of deionized water is added, which is shaken at 25°C for 5 minutes, and then separated into layers. Most of the n-butyraldehyde is dissolved in the water phase, and the upper layer of the extractant A is regenerated.

[0042] The regenerated extractant A was used again to treat fresh 1-hexene feedstock containing n-butyraldehyde 102 ppm under the same conditions as in Example 3. In this example, the content of n-butyraldehyde in 1-hexene after the second extraction was 0.35 ppm, and the removal rate was still as high as 99.66%, with a performance attenuation of less than 0.04% compared with fresh extractant, indicating that the extractant of the present application has excellent regeneration and recycling performance, low loss, can greatly reduce the industrial operation cost, and meets the requirements of green chemical industry and circular economy.

[0043] Example 5: Applicability of extractant A to different carbon number α-olefins 1-butene and 1-octene simulation oils containing n-butyraldehyde 100 ppm were respectively prepared, and treated with extractant A under the conditions of Example 3 (solvent to oil ratio 1:10, 25°C, oscillation for 10 minutes). The residual n-butyraldehyde content was analyzed by the same gas chromatograph.

[0044] In this example, the content of n-butyraldehyde in 1-butene system after refining was reduced to 0.5 ppm, and the content of n-butyraldehyde in 1-octene system after refining was reduced to 0.2 ppm. The results show that the extractant A of the present application has excellent and stable deep deoxidation effect on α-olefins of different carbon numbers (C4 to C8), has a wide range of application, and is suitable for the refining process of various polymerization grade α-olefins.

[0045] Example 6: Performance evaluation of extractant A for removing acetone from 1-hexene Simulation of raw materials: Chromatographically pure 1-hexene was taken, and a precise amount of acetone was added to prepare a simulation raw material oil with an acetone content of (98±2) ppm (weight ratio).

[0046] Extraction experiment: Under the condition of constant temperature at 25°C, 50 grams of the above simulation raw material oil was accurately measured in a 125 mL separatory funnel, and 5 grams of the extractant A prepared in Example 1 was added (solvent to oil mass ratio was 1:10). The separatory funnel was sealed, and manually oscillated vigorously for 10 minutes, and then placed in a constant temperature frame for 30 minutes to allow it to fully separate.

[0047] Sample analysis: After standing and separating, the upper oil phase (refined 1-hexene) was carefully collected, and a gas chromatograph (GC) equipped with a FID detector was used to analyze the residual content of acetone in the upper oil phase. The chromatographic conditions were DB-WAX capillary column and programmed temperature. The detection limit (LOD) of this method was 0.1 ppm.

[0048] Results: GC analysis results showed that the content of acetone in refined 1-hexene was 0.8 ppm, and the removal rate was 99.2%, indicating that the extractant of the present application also has excellent deep removal ability for ketone impurities.

[0049] Example 7: Evaluation of the removal performance of extractant A of butanone (MEK) from 1-hexene The experimental procedure was the same as in Example 6, except that the impurity was replaced with butanone and the initial concentration was set to (105±2) ppm.

[0050] Results: GC analysis showed that the butanone content in the purified 1-hexene was 0.5 ppm, with a removal rate of 99.5%.

[0051] It should be noted that, in this invention, although the specification describes the embodiments, not every embodiment contains only one independent technical solution. This way of describing the specification is only for clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A carbamate extractant for removing oxygen-containing compounds from α-olefins, characterized in that, The extractant has a structure conforming to general formula (I): R 3 N-R 1 -NH-COO-R 2 ; Among them, R 1 For carbon chains (such as alkylene groups) that link urethane groups, R 2 These are substituents on the ester group (often derived from alcohols or cyclic carbonates), while R... 3 These are substituents (such as hydrogen, alkyl, or aryl) that connect to the nitrogen atom (secondary amino group), and the three together determine the overall structure and properties of the molecule.

2. The carbamate extractant for removing oxygen-containing compounds from α-olefins according to claim 1, characterized in that, The R 2 It is -CH(CH3)CH2OH or -CH2CH(CH3)OH.

3. The carbamate extractant for removing oxygen-containing compounds from α-olefins according to claim 1, characterized in that, The R 1 It is one of -CH2CH2- and -CH2CH2CH2-.

4. The carbamate extractant for removing oxygen-containing compounds from α-olefins according to claim 3, characterized in that, The extractant is 1-(2-aminoethylcarbamoyloxy)-2-propanol.

5. The carbamate extractant for removing oxygen-containing compounds from α-olefins according to claim 1, characterized in that, The extractant molecule contains at least one primary amino group and one hydroxyl group.

6. A method for preparing the carbamate extractant for removing oxygen-containing compounds of α-olefins as described in any one of claims 1-5, characterized in that, Includes the following steps: Propylene carbonate is reacted with an excess of primary or secondary amine at a certain temperature for a certain time. After the reaction is completed, the excess primary or secondary amine is removed by vacuum distillation to obtain the carbamate extractant.

7. The method for preparing the carbamate extractant for removing oxygen-containing compounds of α-olefins according to claim 6, characterized in that, The molar ratio of propylene carbonate to primary or secondary amine is 1:2 to 1:

5.

8. The method for preparing the carbamate extractant for removing oxygen-containing compounds of α-olefins according to claim 6, characterized in that, The temperature is 20-120℃, and the time is 1-10 hours.

9. The application of the carbamate extractant according to any one of claims 1-5 for removing oxygen-containing compounds from α-olefins in the removal of oxygen-containing compounds from α-olefins, characterized in that, The oxygen-containing compound is an aldehyde or ketone compound, and the residual concentration of the oxygen-containing compound in the α-olefin after removal is ≤1 ppm.

10. The application of the carbamate extractant for removing oxygen-containing compounds from α-olefins according to claim 9, characterized in that, The application includes: mixing the extractant with α-olefins containing impurities at a mass ratio of 1:20-1:5, performing liquid-liquid extraction at 10-60°C, and collecting the upper purified α-olefins after standing and separating the layers.

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