Modified polymer porous microspheres, and preparation method and application thereof

Abstract

The application belongs to the field of analytical chemistry and relates to a modified high polymer porous microsphere, a preparation method and application thereof. The modified high polymer porous microsphere is prepared by suspension polymerization of styrene, divinylbenzene and acrylonitrile and then sulfonation modification. The chromatographic column filled with the modified high polymer porous microsphere can effectively separate phosphane in ethylene, the analysis time is short, the whole analysis process can be completed within 15 minutes, the minimum detection limit is as low as 10 ppb, the high activity and long period operation of the polyolefin catalyst are effectively ensured, the cost is reduced and the polyolefin resin product quality is improved.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of analytical chemistry, more particularly, relates to a modified high-molecular porous microsphere and a preparation method and application thereof. BACKGROUND

[0002] Ethylene is a basic organic raw material of petroleum chemical industry, about 75% of the petroleum chemical products are produced by using ethylene as raw material. The development of ethylene industry in China drives the development of fine chemical industry, light industry, textile, automobile manufacturing, mechanical and electronic industry, building material industry and modern agriculture, and plays a positive role in the economic field. The ethylene production in the world is one of the important symbols for measuring the development level of a country's petroleum chemical industry.

[0003] In China, the diversification of ethylene upstream raw materials is the future development trend. Oil-based ethylene is produced by steam cracking using naphtha as raw material; coal-based ethylene is produced by Fischer-Tropsch synthesis using coal as raw material; gas-based ethylene is produced by dehydrogenation using ethane as raw material. The diversification of ethylene upstream raw materials also causes more complex impurities in ethylene monomer, for example, phosphine often exists in coal-based ethylene and oil-based ethylene, the specific reason is that the phosphorus element existing in crude oil and coal can be decomposed into phosphine in the process of steam cracking and Fischer-Tropsch synthesis and enter into the ethylene monomer. The Mg / Ti active center of polyethylene Z-N catalyst is extremely sensitive to phosphine, when the phosphine content exceeds 10 ppb, the activity of Z-N catalyst decreases to 80%; when the phosphine content exceeds 100 ppb, the activity of Z-N catalyst is only 50%. Therefore, it is necessary to strictly monitor the content of phosphine in ethylene monomer produced by using crude oil and coal as raw material, so as to reduce the toxicity to the downstream polyethylene catalyst.

[0004] The trace amount of phosphine in ethylene can be detected by helium ionization detector (HID), inductively coupled plasma mass spectrometry (ICP-MS) and mass spectrometry detector (MSD), the sensitivity of the three detectors can meet the requirement of detecting 10 ppb trace phosphine. The critical temperature and pressure of ethylene are about 9.2℃ and 5.02 MPa, ethylene is generally gaseous at room temperature, the boiling point of ethylene is-103.9℃ at normal pressure, and the boiling point of phosphine is-87.5℃ at normal pressure. It is difficult to separate low-boiling-point compounds by different boiling points on a general chromatographic column, and it is necessary to separate them by polarity and other chemical properties. If ethylene and phosphine cannot be completely separated on a chromatographic column, it is difficult to meet the requirement of 10 ppb trace detection. Therefore, it is necessary to develop a gas chromatographic column which can effectively separate ethylene and phosphine, so that the completely separated phosphine can meet the requirement of 10 ppb trace detection. SUMMARY

[0005] The application aims to provide a modified polymer porous microsphere, a preparation method and application thereof, so as to realize effective separation of phosphoranes in ethylene, and make the completely separated phosphoranes meet the trace detection requirement of ppb level, and ensure the high activity and long period operation of polyolefin catalyst.

[0006] In order to achieve the above-mentioned purpose, the application provides a modified polymer porous microsphere, which is prepared by suspension polymerization of styrene, divinylbenzene and acrylonitrile, and then sulfonation modification.

[0007] According to the application, preferably, the specific surface area of the modified polymer porous microsphere is 300-400 m 2 / g, and the pore size of the modified polymer porous microsphere is 2-10 nm.

[0008] The application provides a preparation method of the modified polymer porous microsphere, which comprises the following steps:

[0009] 1) mixing and suspension polymerizing the optionally pretreated styrene, divinylbenzene, acrylonitrile, initiator and porogen to obtain styrene-divinylbenzene-acrylonitrile copolymer porous microspheres;

[0010] 2) sequentially drying and sulfonating the polymer porous microspheres obtained in step 1) to obtain the modified polymer porous microspheres.

[0011] In the above-mentioned step 1), the purity of the styrene, divinylbenzene and acrylonitrile is greater than 90%, and the pretreatment of the styrene, divinylbenzene and acrylonitrile is generally removal of the polymerization inhibitor in the styrene, divinylbenzene and acrylonitrile.

[0012] According to the application, preferably, the mass ratio of the styrene, divinylbenzene, acrylonitrile, initiator and porogen is 30-35:25-30:10-20:1-3:1-3; the initiator is a peroxide and / or azo compound; the porogen is at least one of toluene, paraffin, ethyl acetate, gasoline, kerosene, n-dodecanol and n-octadecanol; the reaction temperature of the suspension polymerization is 60-90℃, the reaction time is 6-9h, and the reaction mode is ultrasonic dispersion gradient heating stirring.

[0013] Further preferably, the styrene is a copolymerization monomer styrene; the divinylbenzene is meta-divinylbenzene; and the initiator is at least one of azobisisobutyronitrile, azobisisoheptyl nitrile, benzoyl peroxide and tert-butyl hydroperoxide. Among them, the meta-divinylbenzene is more likely to form a cross-linked polymer network microsphere.

[0014] In the step 2), preferably, the drying is carried out at a temperature of 100-110℃ for 4-6 hours; the sulfonation treatment is carried out for 6-10 hours at a temperature of 60-90℃ and a pressure of 10KPa-50KPa.

[0015] The sulfonation treatment is carried out by dispersing the dried polymer microspheres into concentrated sulfuric acid, adding different kinds and amounts of sulfonation aids under stirring, and changing the external pressure in a range of 10KPa-50KPa, and sulfonating for 6-10 hours. When the mixed solution is cooled to room temperature, the product is repeatedly washed by ethanol and centrifuged, and the finally separated product is dried to obtain the sulfonated modified polymer porous microsphere powder. The sulfonation aid can be anhydrous sodium sulfate and / or phosphorus pentoxide, and the amount is 3%-6% of the mass of the modified polymer microspheres, and the concentration of the concentrated sulfuric acid is 70%-80%.

[0016] The third aspect of the present application provides a chromatographic column for separating phosphane from ethylene, which comprises a chromatographic column tube and the above-mentioned modified polymer porous microspheres filled in the chromatographic column tube.

[0017] The shape of the chromatographic column tube is not particularly limited, and can be a U-shaped or spiral-shaped tube, and the material can be a glass tube, a stainless steel tube or a plastic tube. The inner diameter of the chromatographic column tube is 1.2-4mm, and the length is 0.5-3m. In order to effectively ensure the separation effect of the chromatographic column and reduce the loss of the chromatographic column, preferably, the packing density of the chromatographic column is 0.2-0.5g / mL, and the mesh number of the modified polymer porous microspheres is 20-100mesh.

[0018] The separation mechanism of the chromatographic column is mainly based on the interaction between the internal molecular pores of the modified polymer microspheres and the adsorption of the gas analysis. The ethylene molecules can quickly pass through the small pores inside the polymer microspheres and are first separated from the chromatographic column, while the relatively large phosphane molecules can only pass through the pores larger than the phosphane molecules themselves, resulting in a longer residence time in the chromatographic column. The sulfonation modification of the polymer microspheres increases the acidic properties, which is easy to chemically and physically adsorb with the basic phosphane, and the adsorption capacity is stronger than the physical affinity adsorption, further increasing the residence time of the phosphane in the chromatographic column. Thus, the separation effect of ethylene raw material and phosphane is achieved.

[0019] The fourth aspect of the present application provides the application of the above-mentioned chromatographic column in gas chromatography detection.

[0020] According to the present application, preferably, the use conditions of the chromatographic column are as follows: the carrier gas is helium, the carrier gas flow rate is 0.8-15mL / min, the carrier gas pressure is 0.3-0.6MPa, the quantitative ring is 0.2-3mL, and the split ratio is 1:5-1:20.

[0021] Compared with the prior art, the present application has the following beneficial effects:

[0022] 1) The preparation raw material of the modified polymer porous microsphere disclosed by the present application is simple and easy to obtain, and the cost is low, the preparation process is simple, there is no environmental pollution, and the consistency of the prepared modified polymer porous microsphere is high.

[0023] 2) The chromatographic column filled with the modified polymer porous microsphere disclosed by the present application can effectively separate phosphoranes in ethylene, the analysis time is short, the whole analysis process can be completed within 15 min, the minimum detection limit is as low as 10 ppb, the high activity and long period operation of the polyolefin catalyst are effectively ensured, the effect of reducing cost and increasing benefit is achieved, and the product quality of the polyolefin resin is improved.

[0024] 3) The chromatographic column filled with the modified polymer porous microsphere disclosed by the present application is suitable for various gas chromatographs, and has a wide application range.

[0025] Other features and advantages of the present application will be described in detail in the following specific embodiment part. BRIEF DESCRIPTION OF DRAWINGS

[0026] The above and other objects, features and advantages of the present application will become more apparent from the following detailed description of exemplary embodiments of the present application taken in conjunction with the accompanying drawings, in which like reference characters refer to the like parts throughout the figures, and in which:

[0027] Figure 1 A synthesis schematic diagram of the modified polymer porous microsphere in one specific embodiment of the present application is shown.

[0028] Figure 2 A structure schematic diagram of a U-shaped chromatographic column in one specific embodiment of the present application is shown.

[0029] Figure 3 A GC-MSD chromatogram for separating phosphoranes in ethylene in Example 1 of the present application is shown.

[0030] Figure 4 A GC-PDHID chromatogram for separating phosphoranes in ethylene in Example 2 of the present application is shown.

[0031] Figure 5 A GC-MSD chromatogram for separating phosphoranes in ethylene in Comparative Example 1 of the present application is shown.

[0032] Figure 6 A chromatogram for separating phosphoranes in ethylene in Comparative Example 2 of the present application is shown.

[0033] Figure 7 A chromatogram for separating phosphoranes in ethylene in Comparative Example 3 of the present application is shown.

[0034] BRIEF DESCRIPTION OF DRAWINGS:

[0035] 1. U-shaped chromatographic column; 2. Modified polymer porous microspheres. DETAILED DESCRIPTION

[0036] The preferred embodiments of the present application will be described in more detail below. Although the preferred embodiments of the present application are described below, it should be understood that the present application can be implemented in various forms and should not be limited by the embodiments set forth herein.

[0037] Example 1

[0038] 1) Preparation of toluene solution

[0039] 3.5 g of comonomer styrene, 3 g of divinylbenzene and 2 g of acrylonitrile, from which the polymerization inhibitor was removed, were mixed with 0.1 g of benzoyl peroxide, 0.1 g of n-octadecanol, in 40 mL of toluene, and deoxygenated by nitrogen, to obtain a toluene solution.

[0040] 2) Preparation of mixed solution

[0041] 0.3 g of cetyltrimethylammonium bromide was mixed with an appropriate amount of distilled water, and after deoxygenation by nitrogen, it was mixed with the toluene solution obtained in step 1) and ultrasonically dispersed for 30 min, to obtain a mixed solution.

[0042] 3) Preparation of polymer porous microspheres

[0043] The mixed solution was transferred to a three-necked flask, and after deoxygenation by nitrogen for 10 min, heating was started, and at a stirring speed of 1040 r / min, the temperature was increased to 60°C, and then the reaction was carried out for 60 min, and then the temperature was increased to 80-85°C, and the reaction was carried out for 90 min, and then the temperature was increased to 85-90°C, and the reaction was carried out for 4 h, and then the heating was stopped. After the solution was cooled to room temperature, water vapor distillation was carried out to remove n-octadecanol, and after filtration, the filter cake was placed in a fat extractor, and extracted with toluene to remove the chain polymer, and the remaining solid was dried and then sieved, to obtain solid polymer porous microspheres of 20-100 mesh.

[0044] 4) Modification of polymer porous microspheres

[0045] 10 g of the solid polymer porous microspheres prepared in step 3) were ultrasonically dispersed in 100 mL of 70% sulfuric acid, and then 0.5 g of anhydrous sodium sulfate and 0.5 g of phosphorus pentoxide were added, and stirring was continued, and a circulating water pump was used to continuously pump and vacuum, so that the external pressure was changed in the range of 10 KPa-50 KPa, and the sulfonation reaction was carried out at 60°C for 10 h. When the mixed solution was cooled to room temperature, the product was washed repeatedly with ethanol and centrifuged, and the finally separated product was dried to obtain sulfonated modified polymer porous microspheres. The modified polymer porous microspheres of 20-100 mesh were sieved and reserved for use. The synthesis process of the modified polymer porous microspheres is as follows: Figure 1As shown, the pore size of the modified polymer porous microspheres prepared is 2-10 nm, and the specific surface area is 300-400 m 2 / g.

[0046] 5) Preparation of chromatographic column

[0047] A U-shaped stainless steel chromatographic column tube with an inner diameter of 2 mm and a length of 3 m was selected. The chromatographic column tube was first rinsed with clean water for 20 min, then 0.1 mol / L sodium hydroxide was poured into the chromatographic column tube and soaked for 2 h, then rinsed with clean water until the effluent was neutral. Then the same method was used to inject ethanol into the chromatographic column tube and soak for 2 h, then rinse with distilled water and ethanol in turn, and finally dry the chromatographic column tube in an oven.

[0048] A funnel was placed at one end of the dried U-shaped chromatographic column tube 1, and the modified polymer porous microspheres 2 prepared in step 4) were filled into the funnel in batches, while the column wall was constantly tapped, until it was filled to 1.5 cm from the column port. The funnel was removed and a silanized glass wool wrapped with thin layer cotton was inserted into the port. Finally, the end of the U-shaped chromatographic column tube 1 was connected to a vacuum pump through a rubber tube.

[0049] A funnel was placed at the other end of the U-shaped chromatographic column tube 1, and after the vacuum pump was turned on, the modified polymer porous microspheres 2 prepared in step 4) were continuously filled into the U-shaped chromatographic column tube 1 through the funnel, and the column wall was constantly tapped to make it fill uniformly and tightly, until it was filled to 1.5 cm from the column port. The funnel was removed and a silanized glass wool wrapped with thin layer cotton was inserted into the port. The glass wool was compressed to keep the filling in the column from moving. The U-shaped chromatographic column tube 1 filled with modified polymer porous microspheres 2 as shown in Figure 2 , with a packing density of 0.2-0.5 g / mL.

[0050] The inlet of the chromatographic column was connected to the gasification chamber, and the outlet end was not connected to the detector. Nitrogen gas was introduced at a flow rate of 15 mL / min. The temperature was raised in stages to 250°C, and aged at 250°C for 24 h.

[0051] 6) Application of chromatographic column

[0052] Agilent 8890B (GC) gas chromatograph, 5977B (MSD) detector, control and recording of the chromatographic separation system were completed by MassHunter workstation.

[0053] The working conditions of the chromatograph were as follows: selected ion mode (SIM) 34, constant temperature of 70°C, constant flow rate of 1.2 mL / min, sample size of 1 mL, split ratio of 1:5, carrier gas of helium (99.9999%), and quantification ring of 0.25 mL.

[0054] The raw material from the polyolefin production device storage tank was introduced into the GC-MSD through a gas valve for separation and detection, and the obtained chromatogram is shown in Figure 3 .

[0055] Example 2

[0056] The difference from Example 1 is that:

[0057] 5) Preparation of the chromatographic column

[0058] A U-shaped stainless steel chromatographic column tube with an inner diameter of 1.5 mm and a length of 2 m was selected.

[0059] 6) Application of the chromatographic column

[0060] An Agilent 8890B (GC) gas chromatograph, a pulsed discharge helium ionization (PDHID) detector, and a chromatographic separation system control and recording by a CDS workstation were used.

[0061] The working conditions of the chromatograph were as follows: the temperature was kept at 60°C, the flow rate was kept at 10 mL / min, the injection volume was 0.25 mL, the split ratio was 1:10, the carrier gas was helium (99.9999%), and the quantitative ring was 3.0 mL.

[0062] The obtained chromatogram is shown in Figure 4 .

[0063] Comparative Example 1

[0064] The difference from Example 1 is that a Gaspro chromatographic column was used, and the obtained chromatogram is shown in Figure 5 .

[0065] Comparative Example 2

[0066] The difference from Example 1 is that an unsulfonated high polymer porous microsphere chromatographic column was used, and the obtained chromatogram is shown in Figure 6 .

[0067] Comparative Example 3

[0068] The difference from Example 1 is that a polymethylsiloxane high polymer porous microsphere chromatographic column was used, and the obtained chromatogram is shown in Figure 7 .

[0069] From Examples 1-2 and Comparative Examples 1-3, it can be seen that the modified polymer porous microsphere chromatographic column of the present application can effectively separate ppb-level phosphorane in ethylene raw material, the separation degree of ethylene and phosphorane is greater than 1.5, and complete baseline separation is achieved. The bonded silica gel as stationary phase chromatographic column cannot effectively separate ppb-level phosphorane in ethylene raw material, the phosphorane is interfered by the main body of ethylene, the peak type is steamed bun peak, greatly reducing the sensitivity of phosphorane; the separation degree of ethylene and phosphorane using the non-sulfonated polymer porous microsphere chromatographic column is less than 1.5, and complete baseline separation cannot be achieved, affecting the accurate quantification of phosphorane; the ethylene and phosphorane peak cannot be separated using the polymethylsiloxane polymer porous microsphere chromatographic column, and qualitative and quantitative analysis of ethylene and phosphorane cannot be achieved.

[0070] The above has described various embodiments of the present application, and the above description is exemplary, not exhaustive, and is not limited to the disclosed embodiments. Many modifications and changes are obvious to those skilled in the art without departing from the scope and spirit of the described embodiments.

Claims

1. A chromatographic column for separating phosphane from ethylene, characterized in that: The chromatographic column comprises a chromatographic column tube and modified polymer porous microspheres filled in the chromatographic column tube; the specific surface area of ​​the modified polymer porous microspheres is 300-400 m 2 / g, the pore size of the modified polymer porous microspheres is 2-10 nm; The preparation method of the modified polymer porous microspheres comprises: 1) 3.5 g of comonomer styrene, 3 g of divinylbenzene, and 2 g of acrylonitrile, from which the polymerization inhibitor has been removed, are mixed with 0.1 g of benzoyl peroxide and 0.1 g of n-octadecyl alcohol in 40 mL of toluene, and the mixture is deoxygenated by nitrogen flow to obtain a toluene solution; 2) Mix 0.3 g of hexadecyltrimethylammonium bromide with an appropriate amount of distilled water, remove oxygen through nitrogen flow, mix with the toluene solution obtained in step 1), and ultrasonically disperse for 30 minutes to obtain a mixed solution; 3) The mixed solution was transferred to a three-necked flask, and nitrogen was passed through it for 10 minutes to remove oxygen. After that, heating was started. At a stirring speed of 1040 r / min, the temperature was raised to 60°C and the reaction was continued for 60 minutes. The temperature was then raised to 80-85°C and the reaction was continued for 90 minutes. The temperature was then raised to 85-90°C and the reaction was continued for 4 hours. Then, heating was stopped. After the solution was cooled to room temperature, it was steam distilled to remove the n-octadecyl alcohol. After filtering, the filter cake was placed in a fat extractor and extracted with toluene to remove the chain polymer. The remaining solid was dried and sieved to obtain solid polymer porous microspheres with a mesh size of 20-100. 4) Ultrasonic dispersion of 10 g of the solid polymer porous microspheres prepared in step 3) into 100 mL of 70% sulfuric acid was performed. 0.5 g of anhydrous sodium sulfate and 0.5 g of phosphorus pentoxide were then added with continuous stirring. A circulating water pump was used to continuously evacuate and release the vacuum, adjusting the external pressure within the range of 10 kPa to 50 kPa. The sulfonation reaction was carried out at 60°C for 10 h.

2. The chromatographic column according to claim 1, characterized in that The divinylbenzene is meta-divinylbenzene.

3. The chromatographic column according to claim 1, characterized in that The packing density of the chromatographic column is 0.2-0.5 g / mL, and the mesh number of the modified polymer porous microspheres is 20-100 mesh.

4. Use of the chromatographic column described in any one of claims 1 to 3 in gas chromatography detection.

5. The use according to claim 4, characterized in that The operating conditions of the chromatographic column are as follows: the carrier gas is helium, the carrier gas flow rate is 0.8-15 mL / min, the carrier gas pressure is 0.3-0.6 MPa, the quantitative loop is 0.2-3 mL, and the split ratio is 1:5-1:20.

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