Method for detecting content of organic ligand in Co-Zn double metal cyanide catalyst

Abstract

The invention discloses a method for detecting the content of organic ligands in a Co-Zn double-metal cyanide catalyst, and belongs to the technical field of analytical chemistry. The detection method comprises the following steps: S1, sample pretreatment: treating a Co-Zn double-metal cyanide catalyst by using a chelating agent, dissolving the Co-Zn double-metal cyanide catalyst in an aqueous solution, and extracting a target analyte to obtain a sample to be detected; s2, preparing a standard solution: preparing a standard solution formed by mixing tert-butyl alcohol and dimethyl phthalate; and S3, sample determination: detecting to obtain chromatograms of the standard solution and the to-be-detected sample through gas chromatography, obtaining peak areas of the tert-butyl alcohol and the dimethyl phthalate, drawing a standard curve according to the corresponding peak areas and concentrations, and calculating to obtain the content of the tert-butyl alcohol and the dimethyl phthalate in the to-be-detected sample. The method disclosed by the invention is simple and convenient to operate, can realize rapid separation of the organic ligands, effectively avoids side reactions, enables detection results to be quicker, more accurate and more reliable, and is good in repeatability.

Description

Technical Field

[0001] The invention relates to the technical field of analytical chemistry, and in particular to a method for detecting the content of organic ligands in a Co-Zn double metal cyanide catalyst. Background Art

[0002] Co-Zn double metal cyanide catalysts (DMC catalysts) are complex complexes based on a double metal cyanide backbone and containing a variety of organic and inorganic ligands. The type and content of the organic ligands significantly influence the catalyst's structure. The addition of organic ligands increases the proportion of amorphous structures, which exhibit excellent catalytic activity and thus affect the catalyst's efficiency. As a highly efficient catalyst for epoxy polymerization, Co-Zn double metal cyanide catalysts produce products with higher molecular weights and lower unsaturation levels compared to conventional acid-base catalysts. Consequently, they have been successfully applied in the industrial production of high-molecular-weight, low-unsaturation polyether polyols.

[0003] During the synthesis of Co-Zn double metal cyanide catalysts, the crystal form is a key factor influencing the catalytic activity. The type and content of the organic ligands, in turn, determine the catalyst's crystal form. During the synthesis process, the amount of organic ligands must be continuously adjusted to achieve the desired crystal form. Therefore, accurate and rapid determination of the organic ligand content in Co-Zn double metal cyanide catalysts is crucial.

[0004] Literature reports suggest that the type and content of organic ligands in Co-Zn double metal cyanide catalysts can be analyzed by thermal decomposition, collecting different fractions, and then using gas chromatography-mass spectrometry for qualitative analysis and gas chromatography for quantitative analysis. However, this method of separating organic ligands through thermal treatment is not only energy-intensive and cumbersome, but can also produce side reactions and cannot guarantee complete dissociation of the organic ligands from the catalyst. These factors can lead to deviations in content determination and inaccurate results.

[0005] In view of this, it is very necessary to invent a method that can simply, quickly and accurately detect the content of organic ligands in Co-Zn double metal cyanide catalysts. Summary of the Invention

[0006] In order to overcome the shortcomings of the prior art, the purpose of the present invention is to provide a method for detecting the content of organic ligands in Co-Zn double metal cyanide catalysts. The method is simple to operate, can achieve rapid separation of organic ligands, and effectively avoids the occurrence of side reactions, making the detection results faster, more accurate, reliable, and reproducible.

[0007] In order to solve the above problems, the technical solutions adopted by the present invention are as follows: A method for detecting the content of organic ligands in a Co-Zn double metal cyanide catalyst comprises the following steps: S1. Sample pretreatment: using a chelating agent to treat the Co-Zn double metal cyanide catalyst to dissolve it in an aqueous solution, extract the target analyte, and obtain a sample to be tested; S2. Prepare standard solution: prepare a standard solution of tert-butyl alcohol and dimethyl phthalate; S3. Sample determination: Obtain chromatograms of the standard solution and the sample to be tested by gas chromatography, obtain the peak areas of tert-butyl alcohol and dimethyl phthalate, draw a standard curve based on the corresponding peak areas and concentrations, and calculate the contents of tert-butyl alcohol and dimethyl phthalate in the sample to be tested.

[0008] As a preferred embodiment of the present invention, step S1 specifically includes the following steps: S11, adding a chelating agent to ultrapure water to prepare a chelating agent aqueous solution with a chelating agent mass percentage of 5-15% (calculated based on the corresponding acid), adding a pH adjuster to adjust the pH to 7, and allowing the solution to stand for use; S12, adding sodium chloride to ultrapure water and dissolving it to prepare a saturated sodium chloride solution; S13. Add the Co-Zn double metal cyanide catalyst to the chelating agent aqueous solution in step S11 and dissolve it by ultrasonication. Add the saturated sodium chloride solution in step S12 and mix well. Pour the mixture into a separatory funnel and extract with ethyl acetate for multiple times. Collect the extract and dilute it to 50 ml with ethyl acetate to obtain a sample to be tested.

[0009] As a preferred embodiment of the present invention, the chelating agent is at least one of ethylenediaminetetraacetic acid, ethylenediaminetetraacetic acid disodium salt, ethylenediaminetetraacetic acid tetrasodium salt, nitrilotriacetic acid trisodium salt, and diethylenetriaminepentaacetic acid.

[0010] As a preferred embodiment of the present invention, the concentration of the pH adjuster is 1-6 mol / L.

[0011] As a preferred embodiment of the present invention, the pH adjuster is an alkali metal hydroxide solution or hydrochloric acid; the alkali metal hydroxide solution is one of sodium hydroxide, potassium hydroxide, and cesium hydroxide.

[0012] As a preferred embodiment of the present invention, step S2 specifically includes the following steps: S21. Prepare standard stock solution: accurately weigh 0.25 g of tert-butyl alcohol, place it in a 50 mL volumetric flask, add ethyl acetate, dilute to the mark, mix well, and set aside; accurately weigh 0.40 g of dimethyl phthalate, place it in a 50 mL volumetric flask, add ethyl acetate, dilute to the mark, mix well, and set aside; S22, preparing a mixed standard solution: diluting the standard stock solution prepared in step 21 to prepare a mixed standard solution with stepwise concentrations.

[0013] As a preferred embodiment of the present invention, the concentration of the tert-butyl alcohol is 25-500 μg / mL, and the concentration of the dimethyl phthalate is 40-800 μg / mL.

[0014] As a preferred embodiment of the present invention, the step concentrations of tert-butanol in the mixed standard solution are 25, 50, 100, 250, and 500 μg / mL, and the step concentrations of dimethyl phthalate are 40, 80, 160, 400, and 800 μg / mL.

[0015] As a preferred embodiment of the present invention, the detection conditions of the gas chromatography in step S3 are as follows: Chromatographic column: 6% cyanopropylphenyl, 94% polydimethylsiloxane, specification 30m*0.32mm*1.8μm; Chromatographic conditions: column temperature was initially 40-60°C, held for 4 min, then raised to 240°C at a rate of 10-20°C / min and held for 10 min; The injection port temperature was 230~250℃, the detector temperature was 250~260℃, the flow rate was 1~2mL / min, the injection volume was 1μL, the carrier gas was nitrogen, and the split ratio was 10~100:1.

[0016] As a preferred embodiment of the present invention, the calculation formula used in step S3 is as follows:

[0017] Wherein, w is the content of the component to be measured in the Co-Zn double metal cyanide catalyst, unit is μg / g; A i is the peak area of ​​the component to be measured; m is the sample mass of the Co-Zn double metal cyanide catalyst, in g; V is the constant volume of the extract, in mL; f is the dilution factor; a is the slope of the standard curve; and b is the intercept of the standard curve on the abscissa.

[0018] Compared with the prior art, the present invention has the following beneficial effects: The present invention uses a chelating agent solution to destroy the structure of a Co-Zn double metal cyanide catalyst, allowing it to dissolve in water. The organic ligand can then be separated through simple extraction. The process is simple and quick to operate. Compared with traditional thermal decomposition separation of organic ligands, the device is simpler, the separation is faster, and side reactions are avoided during sample pretreatment, resulting in more accurate and reliable test results. Experiments have demonstrated accurate and reproducible results, effectively solving the problem of simply, quickly, and accurately measuring the contents of two organic ligands, tert-butyl alcohol and dimethyl phthalate, in a poorly soluble solid Co-Zn double metal cyanide catalyst. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is a standard curve of tert-butyl alcohol prepared in Example 1 of the present invention; Figure 2 This is a standard curve of dimethyl phthalate prepared in Example 1 of the present invention; Figure 3 This is a standard chromatogram of tert-butanol and dimethyl phthalate prepared in Example 1 of the present invention, wherein 1 is tert-butanol and 2 is dimethyl phthalate. DETAILED DESCRIPTION

[0020] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0021] A method for detecting the content of organic ligands in a Co-Zn double metal cyanide catalyst comprises the following steps: S1. Sample pretreatment: Use a chelating agent to treat the Co-Zn double metal cyanide catalyst to dissolve it in an aqueous solution, extract the target analyte, and obtain a sample to be tested. The specific steps are as follows: S11. Add a chelating agent of mass M to ultrapure water to prepare a chelating agent aqueous solution having a chelating agent mass percentage of 5-15% (calculated based on the corresponding acid), and add a pH adjuster of concentration of 1-6 mol / L to adjust the pH to 7, and allow to stand for use; wherein the chelating agent is at least one of ethylenediaminetetraacetic acid, ethylenediaminetetraacetic acid disodium salt, ethylenediaminetetraacetic acid tetrasodium salt, nitrilotriacetic acid trisodium salt, and diethylenetriaminepentaacetic acid. The pH adjuster is an alkali metal hydroxide solution or hydrochloric acid; wherein the alkali metal hydroxide solution is one of sodium hydroxide, potassium hydroxide, and cesium hydroxide; S12, adding sodium chloride to ultrapure water and dissolving it to prepare a saturated sodium chloride solution; S13. Add the Co-Zn double metal cyanide catalyst with a mass of m to the chelating agent aqueous solution with a volume of V1 in step S11 and dissolve it by ultrasonication. Add the saturated sodium chloride solution with a volume of V2 in step S12 and mix evenly. Pour the mixture into a separatory funnel and extract with ethyl acetate for multiple times. Collect the extract and dilute it to 50 ml with ethyl acetate to obtain a sample to be tested.

[0022] S2. Prepare standard solution: Prepare a standard solution of tert-butyl alcohol and dimethyl phthalate. The specific steps are as follows: S21. Prepare standard stock solution: accurately weigh 0.25 g of tert-butanol, place it in a 50 mL volumetric flask, add ethyl acetate, dilute to the mark, mix well, and set aside; accurately weigh 0.40 g of dimethyl phthalate, place it in a 50 mL volumetric flask, add ethyl acetate, dilute to the mark, mix well, and set aside.

[0023] S22, preparing a mixed standard solution: diluting the standard stock solution prepared in step 21 to prepare a mixed standard solution with stepwise concentrations. The concentration of tert-butyl alcohol is 25 to 500 μg / mL, and the concentration of dimethyl phthalate is 40 to 800 μg / mL. Specifically, the stepwise concentrations of tert-butyl alcohol in the mixed standard solution are 25, 50, 100, 250, and 500 μg / mL, and the stepwise concentrations of dimethyl phthalate are 40, 80, 160, 400, and 800 μg / mL.

[0024] S3. Sample determination: Analyze the standard solution and the sample to be tested by gas chromatography to obtain a chromatogram, obtain the peak areas of tert-butyl alcohol and dimethyl phthalate, and use the corresponding peak areas and concentrations to create a standard curve to calculate the content of tert-butyl alcohol and dimethyl phthalate in the sample to be tested. The gas chromatography detection conditions are as follows: Chromatographic column: 6% cyanopropylphenyl, 94% polydimethylsiloxane, specification 30m*0.32mm*1.8μm; Chromatographic conditions: column temperature was initially 40-60°C, held for 4 min, then raised to 240°C at a rate of 10-20°C / min and held for 10 min; The injection port temperature was 230~250℃, the detector temperature was 250~260℃, the flow rate was 1~2mL / min, the injection volume was 1μL, the carrier gas was nitrogen, and the split ratio was 10~100:1.

[0025] The calculation formula is:

[0026] Wherein, w is the content of the component to be measured in the Co-Zn double metal cyanide catalyst, in μg / g; Ai is the peak area of ​​the component to be measured; m is the sample mass of the Co-Zn double metal cyanide catalyst, in g; V is the constant volume of the extract, in mL; f is the dilution factor; a is the slope of the standard curve; and b is the intercept of the standard curve on the abscissa.

[0027] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be noted that the following embodiments do not limit the scope of protection claimed by the present invention.

[0028] Unless otherwise specified, the reagents and devices used in the following examples can be obtained from conventional commercial sources or by existing known methods.

[0029] 1. Testing instruments: gas chromatograph (equipped with FID detector and autosampler), analytical balance (accuracy 0.1 mg), ultrasonic cleaner, pH meter.

[0030] 2. Reagents: Co-Zn double metal cyanide catalyst (homemade), tert-butyl alcohol (AR), dimethyl phthalate (AR), ethyl acetate (AR), ethylenediaminetetraacetic acid (AR), ethylenediaminetetraacetic acid disodium salt (AR, containing crystalline water), ethylenediaminetetraacetic acid tetrasodium salt (AR, containing crystalline water), sodium hydroxide (AR), potassium hydroxide (AR), cesium hydroxide (AR), hydrochloric acid (AR), ultrapure water, trisodium nitrilotriacetate (AR, containing crystalline water), diethylenetriaminepentaacetic acid (AR).

[0031] 3. Materials: beaker, volumetric flask, separatory funnel.

[0032] Example 1 This embodiment provides a method for detecting the content of organic ligands in a Co-Zn double metal cyanide catalyst, comprising the following steps: S1. Sample pretreatment: Use a chelating agent to treat the Co-Zn double metal cyanide catalyst to dissolve it in an aqueous solution, extract the target analyte, and obtain a sample to be tested. The specific steps are as follows: S11. Add 11 g of disodium ethylenediaminetetraacetic acid to 100 mL of ultrapure water to prepare a chelating agent aqueous solution. Use a syringe to add 5 mol / L sodium hydroxide solution to the chelating agent aqueous solution. Measure the pH value with a pH meter until the pH reaches 7. Stop adding the sodium hydroxide solution and let the solution stand for later use.

[0033] S12, adding sodium chloride to ultrapure water and dissolving it to prepare a saturated sodium chloride solution; S13. Place 0.1 g of Co-Zn double metal cyanide catalyst in a 50 mL beaker, add 10 mL of ethylenediaminetetraacetic acid sodium salt solution with pH = 7 in step S11, and ultrasonically dissolve until the solid disappears; add 10 mL of saturated sodium chloride solution, mix well, and transfer to a separatory funnel. Extract with ethyl acetate multiple times, collect the organic phase, and dilute to the scale with ethyl acetate to obtain the sample solution to be tested.

[0034] S2. Prepare standard solution: Prepare a standard solution of tert-butyl alcohol and dimethyl phthalate. The specific steps are as follows: S21. Prepare standard stock solution: accurately weigh 0.25 g of tert-butyl alcohol, place it in a 50 mL volumetric flask, add ethyl acetate, dilute to the mark, mix well, and set aside; accurately weigh 0.40 g of dimethyl phthalate, place it in a 50 mL volumetric flask, add ethyl acetate, dilute to the mark, mix well, and set aside; S22, preparing a mixed standard solution: diluting the standard stock solution prepared in step S21 to prepare a mixed standard solution with stepwise concentrations. Specifically, the stepwise concentrations of tert-butyl alcohol in the mixed standard solution are 25, 50, 100, 250, and 500 μg / mL, and the stepwise concentrations of dimethyl phthalate are 40, 80, 160, 400, and 800 μg / mL.

[0035] S3. Sample determination: Obtain chromatograms of the standard solution and the sample to be tested by gas chromatography, obtain the peak areas of tert-butyl alcohol and dimethyl phthalate, draw a standard curve based on the corresponding peak areas and concentrations, and calculate the contents of tert-butyl alcohol and dimethyl phthalate in the sample to be tested.

[0036] The specific operations are as follows: 1. The detection conditions of gas chromatography are set as follows: Chromatographic column: 6% cyanopropylphenyl, 94% polydimethylsiloxane, specification 30m*0.32mm*1.8μm Chromatographic conditions: column temperature: initial temperature 40-60°C, hold time 4 min, increase temperature at 10-20°C / min to 240°C, hold for 10 min The injection port temperature was 230-250°C, the detector temperature was 250-260°C, the flow rate was 1-2 mL / min, the injection volume was 1 μL, the carrier gas was nitrogen, and the split ratio was 30:1.

[0037] 2. Take an appropriate amount of ethyl acetate and pack it into a 1.5mL automatic injection bottle, numbered 1#, then respectively pack 5 mixed standard solutions of tert-butyl alcohol and dimethyl phthalate obtained in step S22 into a 1.5mL automatic injection bottle, and the concentrations are numbered 2#-6# from small to large; Repeat the sample pretreatment operation step of step S13 5 times to obtain 5 test sample solutions, take these 5 test sample solutions respectively and pack them into the automatic injection bottle, numbered 7#-11#; The automatic injection bottles 1#-11# are placed in the automatic sampler in sequence, the injection sequence is set on the computer instrument software, and the sample is started; 3. Establish a standard curve: Detect by gas chromatography to obtain chromatograms of different concentrations of tert-butyl alcohol and dimethyl phthalate, integrate the corresponding chromatographic peaks to obtain the peak area, and make a standard curve with the corresponding peak area and concentration. The results are shown in Figures 1 to 3, wherein the peak areas of tert-butyl alcohol and dimethyl phthalate are the ordinates, and the concentrations of tert-butyl alcohol and dimethyl phthalate are the abscissas; The contents of tert-butyl alcohol and dimethyl phthalate were calculated by the following formula:

[0038] Wherein, w is the content of the component to be measured in the Co-Zn double metal cyanide catalyst, in μg / g; Ai is the peak area of ​​the component to be measured; m is the sample mass of the Co-Zn double metal cyanide catalyst, in g; V is the constant volume of the extract, in mL; f is the dilution factor; a is the slope of the standard curve; and b is the intercept of the standard curve on the abscissa.

[0039] The methodological characteristics of this embodiment are as follows: 1. Linear range and detection limit The detection limit of the analytical method was calculated based on a signal-to-noise ratio (S / N) of 3, and the quantification limit of the analytical method was calculated based on a signal-to-noise ratio (S / N) of 10. The detection limits for tert-butanol were 2.7 μg / mL, and the detection limits for dimethyl phthalate were 1.8 μg / mL. The quantification limits for tert-butanol were 9 μg / mL, and the quantification limits for dimethyl phthalate were 6 μg / mL. Specific results are shown in Table 1.

[0040] The experimental results in Table 1 show that within the concentration ranges of 25-500 μg / mL of tert-butyl alcohol and 40-800 μg / mL of dimethyl phthalate, the linearity is good and the correlation coefficient is greater than 0.999.

[0041] Table 1 Linear equations, detection limits and quantification limits of tert-butyl alcohol and dimethyl phthalate Unit: μg / mL

[0042] 2. Repeatability The samples to be tested were pretreated 5 times and injected into the test sample sequentially. The repeatability test results are shown in Table 2.

[0043] Table 2 Repeatability test Unit: μg / g

[0044] The data in Table 2 show that the test results have good repeatability.

[0045] 3. Spike recovery test After verification, the spiked recovery rates of tert-butyl alcohol and dimethyl phthalate of this detection method were between 98.4% and 103.5%, and between 99.2% and 102.8%, respectively.

[0046] Example 2 The difference between this embodiment and embodiment 1 is only the difference in sample pretreatment in step S1, and the rest is the same as embodiment 1.

[0047] The specific sample pretreatment operations are as follows: S11. Add 11 g of ethylenediaminetetraacetic acid to 100 mL of ultrapure water to prepare a chelating agent suspension. Use a syringe to add a 5 mol / L sodium hydroxide solution to the chelating agent suspension. Measure the pH value with a pH meter until the pH reaches 7. Stop adding the sodium hydroxide solution and let it stand for later use.

[0048] S12, adding sodium chloride to ultrapure water and dissolving it to prepare a saturated sodium chloride solution; S13. Place 0.1 g of Co-Zn double metal cyanide catalyst in a 50 mL beaker, add 10 mL of ethylenediaminetetraacetic acid sodium salt solution with pH = 7 in step S11, and ultrasonically dissolve until the solid disappears; add 10 mL of saturated sodium chloride solution, mix well, and transfer to a separatory funnel. Extract with ethyl acetate multiple times, collect the organic phase, and dilute to the scale with ethyl acetate to obtain the sample solution to be tested.

[0049] The detection was performed according to the detection method of Example 1. The detection results were: tert-butanol 66925 μg / g, dimethyl phthalate 170036 μg / g.

[0050] Example 3 The difference between this embodiment and embodiment 1 is only that the sample pretreatment in step S1 is different, and the rest is the same as embodiment 1.

[0051] The specific sample pretreatment operations are as follows: S11. Add 14 g of tetrasodium ethylenediaminetetraacetic acid to 100 mL of ultrapure water to prepare a chelating agent aqueous solution. Use a syringe to add 5 mol / L hydrochloric acid solution to the chelating agent aqueous solution. Measure the pH value with a pH meter until the pH reaches 7. Stop adding the hydrochloric acid solution and let it stand for later use.

[0052] S12, adding sodium chloride to ultrapure water and dissolving it to prepare a saturated sodium chloride solution; S13. Place 0.1 g of Co-Zn double metal cyanide catalyst in a 50 mL beaker, add 10 mL of ethylenediaminetetraacetic acid sodium salt solution with pH = 7 in step S11, and ultrasonically dissolve until the solid disappears; add 10 mL of saturated sodium chloride solution, mix well, and transfer to a separatory funnel. Extract with ethyl acetate multiple times, collect the organic phase, and dilute to the scale with ethyl acetate to obtain the sample solution to be tested.

[0053] The detection was performed according to the detection method of Example 1. The detection results were: tert-butanol 67912 μg / g, dimethyl phthalate 173025 μg / g.

[0054] Example 4 The difference between this embodiment and embodiment 1 is only that the sample pretreatment in step S1 is different, and the rest is the same as embodiment 1.

[0055] The specific sample pretreatment operations are as follows: S11. Add 9 g of trisodium nitrilotriacetate to 100 mL of ultrapure water to prepare a chelating agent aqueous solution. Use a syringe to add 5 mol / L hydrochloric acid solution to the chelating agent aqueous solution. Measure the pH value with a pH meter until the pH reaches 7. Stop adding the hydrochloric acid solution and let it stand for later use.

[0056] S12, adding sodium chloride to ultrapure water and dissolving it to prepare a saturated sodium chloride solution; S13. Place 0.1 g of Co-Zn double metal cyanide catalyst in a 50 mL beaker, add 10 mL of sodium nitrilotriacetic acid solution with a pH of 7 in step S11, and ultrasonically dissolve until the solid disappears; add 10 mL of saturated sodium chloride solution, mix well, and transfer to a separatory funnel. Extract with ethyl acetate multiple times, collect the organic phase, and dilute to the scale with ethyl acetate to obtain the sample solution to be tested.

[0057] The detection was performed according to the detection method of Example 1. The detection results were: tert-butanol 68019 μg / g, dimethyl phthalate 174318 μg / g.

[0058] Example 5 The difference between this embodiment and embodiment 1 is only that the sample pretreatment in step S1 is different, and the rest is the same as embodiment 1.

[0059] The specific sample pretreatment operations are as follows: S11. Add 14 g of diethylenetriaminepentaacetic acid to 100 mL of ultrapure water to prepare a chelating agent aqueous solution. Use a syringe to add a 5 mol / L sodium hydroxide solution to the chelating agent aqueous solution. Measure the pH value with a pH meter until the pH reaches 7. Stop adding the sodium hydroxide solution and let it stand for later use.

[0060] S12, adding sodium chloride to ultrapure water and dissolving it to prepare a saturated sodium chloride solution; S13. Place 0.1 g of Co-Zn double metal cyanide catalyst in a 50 mL beaker, add 10 mL of sodium diethylenetriamine pentaacetate solution with pH = 7 in step S11 and ultrasonically dissolve until the solid disappears; add 10 mL of saturated sodium chloride solution, mix well and transfer to a separatory funnel, extract with ethyl acetate multiple times, collect the organic phase, and dilute to the scale with ethyl acetate to obtain the sample solution to be tested.

[0061] The detection was performed according to the detection method of Example 1. The detection results were: tert-butanol 68235 μg / g, dimethyl phthalate 175593 μg / g.

[0062] Comparative Example 1 A method for detecting the content of organic ligands in a Co-Zn double metal cyanide catalyst comprises the following steps: 3g of Co-Zn double metal cyanide catalyst was placed in a 100mL flask and heated in stages to separate and collect the organic ligands. The first stage was maintained at 150°C to separate tert-butyl alcohol; the second stage was maintained at 300°C to separate dimethyl phthalate. The entire process was carried out under a nitrogen atmosphere, with high-purity nitrogen dried in an anhydrous calcium chloride and molecular sieve drying tower flowing at a flow rate of 50mL / min to prevent oxidation of the organic matter and remove the pyrolysis products. The pyrolysis products were introduced into a glass test tube placed in a cold trap (-20°C) and condensed at the bottom of the test tube. The separation was completed until no more product flowed out. After cooling, the separated product in the glass test tube was dissolved in ethyl acetate, the glass tube was rinsed, and the solutions were combined.

[0063] The detection was performed according to the detection method of Example 1. The detection results were: tert-butanol 41545 μg / g, dimethyl phthalate 128974 μg / g.

[0064] By comparison, it can be seen that the test results of Examples 1 to 5 are basically consistent, proving that the use of a chelating agent to pre-treat the Co-Zn double metal cyanide catalyst can effectively improve the accuracy of the test results of the organic ligand content. Comparing the results of Examples 1 to 5 with those of Comparative Example 1, it can be seen that the test results of Comparative Example 1 are significantly lower. This is because the thermal separation method used in Comparative Example 1 may result in product loss or incomplete thermal separation. In summary, the detection method of the present invention is simple to operate, can achieve rapid separation of organic ligands, and effectively avoids the occurrence of side reactions, making the detection results faster, more accurate, reliable, and reproducible.

[0065] The above-described embodiments merely illustrate the implementation methods of the present invention, and their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art may make various modifications and improvements without departing from the scope of the present invention, and these modifications and improvements fall within the scope of protection of the present invention. Therefore, the protection of the present invention shall be subject to the appended claims.

Claims

1. A method for detecting the content of organic ligands in a Co-Zn double metal cyanide catalyst, characterized in that: The following steps are involved: S1. Sample pretreatment: using a chelating agent to treat the Co-Zn double metal cyanide catalyst to dissolve it in an aqueous solution, extract the target analyte, and obtain a sample to be tested; S2. Prepare standard solution: prepare a standard solution of tert-butyl alcohol and dimethyl phthalate; S3. Sample determination: Obtain chromatograms of the standard solution and the sample to be tested by gas chromatography, obtain the peak areas of tert-butyl alcohol and dimethyl phthalate, draw a standard curve based on the corresponding peak areas and concentrations, and calculate the contents of tert-butyl alcohol and dimethyl phthalate in the sample to be tested.

2. The method for detecting the content of organic ligands in a Co-Zn double metal cyanide catalyst according to claim 1, wherein: The step S1 specifically includes the following steps: S11, adding a chelating agent to ultrapure water to prepare a chelating agent aqueous solution with a chelating agent mass percentage of 5-15%, and adding a pH regulator to adjust the pH to 7, and letting it stand for standby use; S12, adding sodium chloride to ultrapure water and dissolving it to prepare a saturated sodium chloride solution; S13. Add the Co-Zn double metal cyanide catalyst to the chelating agent aqueous solution in step S11 and dissolve it by ultrasonication. Add the saturated sodium chloride solution in step S12 and mix well. Pour the mixture into a separatory funnel and extract with ethyl acetate for multiple times. Collect the extract and dilute it to 50 mL with ethyl acetate to obtain a sample to be tested.

3. The method for detecting the content of organic ligands in a Co-Zn double metal cyanide catalyst according to claim 2, wherein: The chelating agent is at least one of ethylenediaminetetraacetic acid, ethylenediaminetetraacetic acid disodium salt, ethylenediaminetetraacetic acid tetrasodium salt, nitrilotriacetic acid trisodium salt, and diethylenetriaminepentaacetic acid.

4. The method for detecting the content of organic ligands in a Co-Zn double metal cyanide catalyst according to claim 2, wherein: The concentration of the pH regulator is 1-6 mol / L.

5. The method for detecting the content of organic ligands in the Co-Zn double metal cyanide catalyst according to claim 2 or 4, characterized in that: The pH regulator is an alkali metal hydroxide solution or hydrochloric acid; the alkali metal hydroxide solution is one of sodium hydroxide, potassium hydroxide and cesium hydroxide.

6. The method for detecting the content of organic ligands in a Co-Zn double metal cyanide catalyst according to claim 1, wherein: The step S2 specifically includes the following steps: S21. Prepare standard stock solution: accurately weigh 0.25 g of tert-butyl alcohol, place it in a 50 mL volumetric flask, add ethyl acetate, dilute to the mark, mix well, and set aside; accurately weigh 0.40 g of dimethyl phthalate, place it in a 50 mL volumetric flask, add ethyl acetate, dilute to the mark, mix well, and set aside; S22, preparing a mixed standard solution: diluting the standard stock solution prepared in step 21 to prepare a mixed standard solution with stepwise concentrations.

7. The method for detecting the content of organic ligands in a Co-Zn double metal cyanide catalyst according to claim 6, wherein: The concentration of the tert-butyl alcohol is 25-500 μg / mL, and the concentration of the dimethyl phthalate is 40-800 μg / mL.

8. The method for detecting the content of organic ligands in a Co-Zn double metal cyanide catalyst according to claim 7, wherein: The step concentrations of tert-butanol in the mixed standard solution are 25, 50, 100, 250, and 500 μg / mL, and the step concentrations of dimethyl phthalate are 40, 80, 160, 400, and 800 μg / mL.

9. The method for detecting the content of organic ligands in a Co-Zn double metal cyanide catalyst according to claim 1, wherein: The detection conditions of the gas chromatography in step S3 are as follows: Chromatographic column: 6% cyanopropylphenyl, 94% polydimethylsiloxane, specification 30m*0.32mm*1.8μm; Chromatographic conditions: column temperature was initially 40-60°C, held for 4 min, then raised to 240°C at a rate of 10-20°C / min and held for 10 min; The injection port temperature was 230~250℃, the detector temperature was 250~260℃, the flow rate was 1~2mL / min, the injection volume was 1μL, the carrier gas was nitrogen, and the split ratio was 10~100:

1.

10. The method for detecting the content of organic ligands in a Co-Zn double metal cyanide catalyst according to claim 1, wherein: The calculation formula used in step S3 is as follows: Wherein, w is the content of the component to be measured in the Co-Zn double metal cyanide catalyst, unit is μg / g; A i is the peak area of ​​the component to be measured; m is the sample mass of the Co-Zn double metal cyanide catalyst, in g; V is the constant volume of the extract, in mL; f is the dilution factor; a is the slope of the standard curve; and b is the intercept of the standard curve on the abscissa.

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