Method for measuring content of acrolein in propylene oxidation reaction liquid-phase product

Abstract

The invention belongs to the technical field of organic matter detection, and discloses a method for determining the content of acrolein in a propylene oxidation reaction liquid-phase product through gas chromatography. The determination method comprises the following steps: S1, controlling chromatographic conditions; s2, preparing a calibration curve solution, and selecting isobutanol as an internal standard substance; s3, drawing a correction curve; s4, detecting a sample to be detected; and S5, preparing an acrolein standard solution to verify a detection result. According to the method disclosed by the invention, the separation of acrolein, propionaldehyde and acetone is effectively realized by a method of combining quantification by adding isobutanol as an internal standard agent into a sample and segmented control of carrier gas flow during chromatographic determination, so that the effect of accurately quantifying the content of acrolein in a propylene oxidation reaction liquid-phase product is achieved.

Description

Technical Field

[0001] This invention belongs to the field of organic matter detection technology, specifically relating to a method for determining the content of acrolein in the liquid phase product of propylene oxidation reaction by gas chromatography. Background Technology

[0002] Acrolein, an important organic compound with the molecular formula C3H4O, is chemically highly reactive due to its conjugated structure of carbon-carbon double bonds and aldehyde groups. It is a colorless, volatile, and toxic liquid with a strong, pungent odor; its vapor is highly irritating to the eyes and mucous membranes. It is a key chemical intermediate widely used in the synthesis of products such as methylpyridine, methionine, and 1,3-propanediol, and is of great significance in the pharmaceutical, food, and cosmetic industries.

[0003] The liquid-phase products of acrolein preparation via propylene oxidation are complex, containing various similar compounds such as acetaldehyde, acrolein, propionaldehyde, acetone, acetic acid, and acrylic acid (as shown in Table 1). Effective separation of acrolein is necessary for quantification using gas chromatography. However, in the liquid-phase products, the boiling points of acrolein, propionaldehyde, and acetone are 52.5℃, 48.5℃, and 56.5℃, respectively, with dipole moments of 3.1, 2.5, and 2.9, indicating similar molecular polarities. Therefore, effective separation of acrolein, propionaldehyde, and acetone is very difficult or time-consuming when using gas chromatography. If the separation of propionaldehyde and acetone is neglected, their chromatographic peaks may be masked by the acrolein peak, making accurate quantification of acrolein difficult.

[0004] Table 1: Properties of acetaldehyde, acrolein, propionaldehyde, acetone, acetic acid, and acrylic acid

[0005] In the prior art, Chinese Patent Application No. 2016102892549 discloses a method for analyzing the acrylic acid content in a liquid mixture using gas chromatography, specifically involving the determination of acrylic acid content in the reaction product of propylene oxidation to prepare acrolein. The system employs a flame ionization detector (FID), a 3mm × 3m packed column, and uses acetone or butanone as an internal standard. First, the total acid molar concentration in the test solution is determined by acid-base titration. Then, the contents of acrylic acid and acetic acid are determined by gas chromatography. Finally, the molar concentration of acrylic acid is measured, and the acrylic acid concentration in the acrylic acid and acetic acid standard samples is between 93.2% and 99.5 mol%.

[0006] Chinese Patent Application No. 2014100371552 discloses a method for determining acrylic acid in workplace air using ion chromatography. Specifically, the system uses a Metrosep A SUPP 4-250 / 4.0 anion exchange column with dimensions of 4.0 mm × 250.0 mm. Acrylic acid is collected using silicone tubing, and an environmentally friendly and pollution-free sodium carbonate / sodium bicarbonate solution is used as the desorption solvent and chromatographic mobile phase. This establishes a rapid, sensitive, accurate, environmentally friendly, and low-cost method for the ion chromatography detection of acrylic acid in workplace air. The method exhibits good linearity for acrylic acid in the range of 0.1 μg to 4 μg / ml.

[0007] Chinese Patent Application No. 2015103166450 discloses an analytical method for the acetic acid content in the liquid phase products of propylene oxidation reaction, specifically involving the determination of the acetic acid content in the liquid phase reaction products of propylene oxidation to acrolein. The system employs a flame ionization detector (FID), a chromatographic column (3 mm × 3 m packed column), and uses acetone or butanone as an internal standard. First, the total acid molar concentration in the test solution is determined by acid-base titration. Then, the molar percentage content of acrylic acid and acetic acid is determined by gas chromatography. Finally, the molar concentration of acetic acid is measured. The acrylic acid content in the acrylic acid and acetic acid standard samples is between 93.2% and 99.5 mol%.

[0008] Chinese Patent Application No. 2016102893950 discloses a method for determining the acetic acid content in the liquid phase product of propylene oxidation reaction, specifically relating to the determination of the acetic acid content in the liquid phase product of acrolein oxidation reaction to prepare acrolein. The system employs a flame ionization detector (FID), a chromatographic column (3 mm × 3 m packed column), and uses dimethyl sebacate as an internal standard, with a concentration range of 0.00001–0.00009 mol / L.

[0009] Chinese Patent Application No. 2016102908123 discloses a method for determining the acetaldehyde content in a liquid mixture, specifically relating to the determination of acetaldehyde content in the liquid product of the acrolein oxidation reaction to prepare acrylic acid. The system employs a flame ionization detector (FID), a chromatographic column (3 mm × 3 m packed column), and uses butanone as an internal standard, with a concentration range of 0.00001–0.00009 mol / L.

[0010] Chinese Patent Application No. 2016102896304 discloses a method for determining the content of unsaturated aldehydes in a liquid mixture, specifically relating to the determination of acrolein content in the liquid product of the acrolein oxidation reaction to prepare acrylic acid. The system employs a flame ionization detector (FID), a chromatographic column (3 mm × 3 m packed column), and uses butanone as an internal standard, with a concentration range of 0.00001–0.00009 mol / L.

[0011] "Determination of Acrolein Content in Catalytic Incineration Tail Gas of Acrylic Acid Production by Gas Chromatography" (Author: Lu Junliang; Zhejiang Satellite Holding Group, *Chemical Analysis and Metrology*, Vol. 18, No. 6, 2009, pp. 58-59). This paper describes a system for determining the acrolein content in the catalytic incineration tail gas of acrylic acid production using capillary gas chromatography. The chromatographic column was an FFAP (25 m × 0.53 mm, 1.0 μm), and the detector was a flame ionization detector (FID). 1,4-dioxane was used as an internal standard. The detection limit was 0.029 mg / m³. 3 The relative standard deviations of the determination results ranged from 0.93% to 2.48% (n=5), and the recoveries ranged from 97.4% to 103.1%. This paper determined that the acrolein content was no higher than 4 mg / L. -1 This method is suitable for determining the content of acrolein in the catalytic combustion tail gas of acrylic acid production, and is suitable for determining the content of acrolein at low levels.

[0012] "Determination of Acrolein, Acetic Acid, and Acrylic Acid Content in Acrylic Acid Tail Gas from Propylene Oxidation Production by Gas Chromatography" (Author: Chen Kejie; Zhejiang Satellite Petrochemical Co., Ltd., *Chemical Analysis and Metrology*, Vol. 22, No. 5, 2013, pp. 92-93). The system employs capillary gas chromatography to determine the contents of acrolein, acetic acid, and acrylic acid in the tail gas from propylene oxidation production of acrylic acid. The chromatographic column is FFAP (30m × 0.53mm, 1μm), and the detector is a flame ionization detector (FID). Quantification is performed using the external standard method. The detection limits for acrolein, acetic acid, and acrylic acid in the tail gas sample are 0.025, 0.033, and 0.031 mg / m³, respectively. The relative deviations of the determination results are 0.97%–2.63% (n = 5), and the spiked recoveries are 98.29%–103.60%. This paper records that the acrylic acid production process often uses catalytic incineration to treat wastewater, waste acid, and waste gas for harmless treatment. However, the treated tail gas still contains a certain amount of acrolein, which affects the atmospheric environment. The state has regulations on the atmospheric emissions of acrolein from industrial enterprises. Measuring the acrolein content in the incineration tail gas is very helpful in adjusting the process parameters of the catalytic incinerator, controlling the acrolein content in the tail gas, and meeting environmental requirements. This method is applicable to the determination of the contents of acrolein, acetic acid, and acrylic acid in the waste gas after catalytic incineration of acrylic acid.

[0013] "Determination of Acetonitrile, Acetone, and Acrolein in Industrial Acrylonitrile by Capillary Gas Chromatography" (Author: An Cailing, *Analytical Testing Technology and Instruments*, Vol. 12, No. 2, 2006, pp. 112-114). This paper describes a system for determining the content of acetonitrile, acetone, and acrolein in acrylonitrile using capillary gas chromatography. The chromatographic column was a 50 m × 0.32 mm × 0.53 μm FFAP-bonded quartz elastic capillary column. Quantification was performed using the internal standard method (butanone). The column temperature was 54℃, and the carrier gas linear velocity was 15 cm / s. The recovery rate and RSD of the determination of acetonitrile, acetone, and acrolein in industrial acrylonitrile met the analytical requirements.

[0014] The thesis, "Research on Gas Chromatographic Analysis of Propylene Oxidation Reaction Gas" (author: Li Luqing, Master's Thesis, Lanzhou University, 2014), describes that the main components of the propylene oxidation reaction gas include propylene, acrylic acid, acrolein, acetic acid, oxygen, nitrogen, carbon monoxide, carbon dioxide, water, and acetone. Conventional methods are insufficient for accurately determining these components. Currently, there are no standardized national or industry standards specifying methods for determining the composition of the propylene oxidation reaction gas. This thesis, based on the actual conditions of the acrylic acid unit at Lanzhou Petrochemical Company, explored optimal sampling conditions under different unit loads and determined a method for accurately collecting samples. Meanwhile, a gas chromatography method was developed using a gas chromatograph. This method utilizes two six-way valves and one four-way valve to switch the sample gas multiple times into different chromatographic columns (two φ3.0mm×3m PEG-20M 10% Shimalite-TPA columns, one φ3.0mm×2.5m Porapak Q column, and one φ3.0mm×2.5m Molecular Sieve 13X column). This method can analyze various required components of propylene oxidation reaction gas in a single analysis.

[0015] The paper, "Research on Propylene Oxidation Process" (author: Sang Lei, Master's Thesis, Shandong University of Science and Technology, 2007), describes how propylene oxide, acrolein, acrylic acid, acetone, and other products can be produced through selective oxidation processes using propylene as a raw material.

[0016] "Microscopic Reaction Kinetics of Selective Oxidation of Propylene to Acetone" (Author: Li Mingshi; Jiangsu Institute of Technology, Proceedings of the 11th National Conference on Youth Catalysis, 2007) This paper describes the selective oxidation of propylene to acetone under certain conditions and proposes that enhancing the acidity and redox properties of the catalyst and achieving a match between the two may be the direction for seeking good catalysts for the selective oxidation of olefins to ketones.

[0017] The methods described in the above patents and papers for determining the liquid phase products (or liquid phase mixtures) in the preparation of acrolein / acrylic acid by propylene oxidation involve acrolein, acrylic acid, and acetic acid as the liquid phase products, without mentioning the separation of acrolein, propionaldehyde, and acetone. However, the literature mentions that propionaldehyde and acetone exist as byproducts of the reaction at low concentrations in the liquid phase products. Because acrolein, propionaldehyde, and acetone have similar polarities, effective separation of them using gas chromatography is very difficult, or the separation time is very long. If the separation of acetone is neglected, the chromatographic peak of acetone may be masked by the chromatographic peak of acrolein, making accurate quantification of acrolein difficult.

[0018] Therefore, there is an urgent need to provide a new method for determining the acrolein content in the liquid phase products of propylene oxidation reaction. This method can distinguish between acrolein, acetone, and propionaldehyde, thus enabling the measurement of acrolein content. Summary of the Invention

[0019] The present invention aims to at least solve one of the technical problems existing in the prior art. To this end, the present invention proposes a method for determining the acrolein content in the liquid phase products of propylene oxidation reaction using gas chromatography. The method of the present invention can separate acrolein, acetone, and propionaldehyde, thereby enabling the precise measurement of acrolein content.

[0020] To address the problem of accurate quantification of acrolein in the liquid phase products of propylene oxidation in existing technologies, this invention combines the addition of isobutanol as an internal standard for quantification with segmented control of carrier gas flow rate during chromatographic determination. This effectively separates acrolein, propionaldehyde, and acetone, thereby achieving accurate quantification of the acrolein content in the liquid phase products of propylene oxidation reaction.

[0021] Specifically, a method for determining the acrolein content in the liquid phase product of propylene oxidation reaction by gas chromatography includes the following steps: S1. Chromatographic conditions control: The chromatographic column used is a cyanopropylphenyl-dimethylpolysiloxane capillary column, the carrier gas is nitrogen, the initial column flow rate is 0.4-0.6 mL / min, held for 11-14 min, and then the column flow rate is increased to 2.2-2.5 mL / min at a rate of 3.8-4.0 mL / min and held for 2-3 min; split injection is used. S2. Preparation of calibration curve solution: Weigh acrolein standard and internal standard isobutanol into multiple volumetric flasks according to the mass shown in Table 2, then add deionized water, shake well and set aside to use to obtain standard solution. Table 2: Sample weight of acrolein standard and internal standard isobutanol

[0022] S3. Construction of the calibration curve: Inject the standard solution prepared in step S2 into the syringe, and determine the peak areas of acrolein and the internal standard isobutanol according to the gas chromatography conditions. Plot the mass ratio as the abscissa and the peak area ratio as the ordinate, and find the linear regression equation, denoted as y=ax+b, as the calibration curve. S4. Detection of the test sample: Take the liquid phase product of the propylene oxidation reaction as the test sample. Accurately weigh the test sample and place it in a volumetric flask. Then weigh the internal standard isobutanol and add it to the volumetric flask. Add deionized water, and then inject the sample according to the gas chromatography conditions in step S1. After all components have eluted, obtain the peak area ratio of the test sample and the internal standard from the chromatogram, which is A. s / A r The mass ratio of the two components is obtained based on the calibration curve in step S3, and then the acrolein content W in the sample to be tested is calculated using the following formula: W=(a×A s / A r +b)×M r / M×100%; in: W represents the acrolein content in the sample to be tested; A s This indicates the peak area of ​​acrolein in the sample being tested; A r This indicates the peak area of ​​the internal standard isobutanol in the sample to be tested; M r This indicates the mass of the internal standard isobutanol in the sample to be tested; M represents the mass of the sample to be tested; a and b can be obtained from the linear regression equation in step S3; S5. Prepare acrolein standard solution to verify the test results: Weigh acrolein and place it in a volumetric flask, then add deionized water to obtain an acrolein standard solution. At this time, the acrolein content in the acrolein standard solution is similar to the acrolein content W in step S4. Weigh the internal standard isobutanol and add it to the volumetric flask. Then, inject the sample according to the gas chromatography conditions in step S1. After the components have completely eluted, obtain the peak area of ​​acrolein in the acrolein standard solution, the peak area of ​​the internal standard, and the ratio of their peak areas from the chromatogram. Compare the values ​​obtained in step S4 to verify the reliability of the test results.

[0023] Preferably, in step S1, the initial column flow rate is 0.6 mL / min, maintained for 14 min, and then the column flow rate is increased to 2.5 mL / min at a rate of 4.0 mL / min and maintained for 2 min.

[0024] Preferably, in step S1, the chromatographic column is a 30m×0.32mm×1.8μm WM-1301 (6% cyanopropylphenyl-94% dimethylpolysiloxane) capillary column.

[0025] Preferably, the mass fractions of cyanopropylphenyl and dimethylpolysiloxane in the capillary column are 6% and 94%, respectively.

[0026] Preferably, in step S1, the detector used is a flame ionization detector (FID).

[0027] Preferably, in step S1, the initial column temperature is 45-48℃, held for 8-9 minutes, and then increased to 170-180℃ at a rate of 30-40℃ / min, held for 1-2 minutes.

[0028] Preferably, in step S1, the temperature of the vaporization chamber is 190-200℃, and the temperature of the detector is 245-250℃.

[0029] Preferably, in step S1, the split ratio when using split injection is 10:1.

[0030] Preferably, in step S2, the contents are weighed into five 10mL volumetric flasks, accurate to 0.0001g, and then deionized water is added to a final volume of 5g, accurate to 0.0001g.

[0031] Preferably, in step S3, 0.2 μL of the standard solution prepared in step S2 is injected using a 1 μL microsyringe.

[0032] Preferably, in step S4, the liquid phase product of the propylene oxidation reaction is taken as the sample to be tested. The sample to be tested is accurately weighed to 0.0001 g and placed in a 10 mL volumetric flask. The internal standard isobutanol is then accurately weighed to 0.0001 g and placed in the same 10 mL volumetric flask. Deionized water is then added to 5 g to 0.0001 g and placed in the same 10 mL volumetric flask. The sample is then injected into the gas chromatographic conditions of step S1, with an injection volume of 0.2 μL.

[0033] Preferably, in step S5, acrolein is accurately weighed to a precision of 0.0001 g and placed in a 10 mL volumetric flask. Deionized water is then added to a final volume of 5 g, accurate to a precision of 0.0001 g, and placed in the same 10 mL volumetric flask. At this point, the acrolein content in the acrolein standard solution is similar to the acrolein content W in S4. The internal standard isobutanol is then accurately weighed to a precision of 0.0001 g and placed in the same 10 mL volumetric flask. The sample is then injected according to gas chromatography conditions, with an injection volume of 0.2 μL.

[0034] Preferably, the determination method includes the following steps: S1. Chromatographic conditions: A 30m × 0.32mm × 1.8μm WM-1301 (6% cyanopropylphenyl-94% dimethylpolysiloxane) capillary column was used. High-purity nitrogen was used as the carrier gas. A flame ionization detector (FID) was used. The initial column temperature was 48℃, held for 9 min, and then increased to 180℃ at a rate of 40℃ / min, held for 1 min. The initial column flow rate was 0.6mL / min, held for 11-14 min, and then increased to 2.5mL / min at a rate of 4.0mL / min, held for 2-3 min. The vaporization chamber temperature was 200℃, the detector temperature was 250℃, and split injection was used with a split ratio of 10:1. S2. Preparation of calibration curve solution: Weigh acrolein standard and internal standard isobutanol into five 10mL volumetric flasks according to the mass shown in Table 2, accurate to 0.0001g. Then add deionized water to 5g, accurate to 0.0001g, and shake well for later use. S3. Plotting the calibration curve: Inject 0.2 μL of the standard solution prepared in step S2 into a 1 μL microsyringe, and determine the peak areas of acrolein and the internal standard isobutanol according to the gas chromatography conditions. Plot the mass ratio as the abscissa and the peak area ratio as the ordinate to obtain the linear regression equation, denoted as y=ax+b. S4. Detection of the sample to be tested: Take the liquid phase product of the propylene oxidation reaction as the sample to be tested. Accurately weigh the sample to be tested to a value of 0.0001 g and place it in a 10 mL volumetric flask. Then accurately weigh the internal standard isobutanol to a value of 0.0001 g and place it in the same 10 mL volumetric flask. Add deionized water to a value of 5 g to a value of 0.0001 g and place it in the same 10 mL volumetric flask. Inject the sample according to the gas chromatography conditions. The injection volume is 0.2 μL. After the components have completely eluted, obtain the peak area ratio of the sample to the internal standard from the chromatogram, which is As / Ar. Calculate the mass ratio of the two components according to the calibration curve in step S3. Then calculate the content W of acrolein in the sample to be tested using the following formula: W=(a×A s / A r +b)×M r / M×100%; in: W represents the acrolein content in the sample to be tested; A s This indicates the peak area of ​​acrolein in the sample being tested; A r This indicates the peak area of ​​the internal standard isobutanol in the sample to be tested; M r This indicates the mass of the internal standard isobutanol in the sample to be tested; M represents the mass of the sample to be tested; a and b can be obtained from the linear regression equation in step S3; S5. Preparation of acrolein standard solution to verify the test results: Accurately weigh acrolein to the nearest 0.0001 g and place it in a 10 mL volumetric flask. Add deionized water to the nearest 5 g, accurate to the nearest 0.0001 g, and place it in the same 10 mL volumetric flask. At this point, the acrolein content in the acrolein standard solution is similar to the acrolein content W in S4. Then accurately weigh the internal standard isobutanol to the nearest 0.0001 g and place it in the same 10 mL volumetric flask. Inject the sample according to gas chromatography conditions, with an injection volume of 0.2 μL. After the components have completely eluted, obtain the peak area of ​​acrolein in the acrolein standard solution, the peak area of ​​the internal standard, and the ratio of their peak areas from the chromatogram. Compare these values ​​with those obtained in S4 to verify the reliability of the test results.

[0035] The above-mentioned gas chromatography method for determining the acrolein content in the liquid phase product of propylene oxidation reaction has applications in the pharmaceutical, food, or cosmetic fields.

[0036] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0037] This invention effectively separates acrolein, propionaldehyde, and acetone by combining the addition of isobutanol as an internal standard for quantification with segmented control of carrier gas flow rate during chromatographic determination. This results in accurate quantification of the acrolein content in the liquid phase products of propylene oxidation reaction.

[0038] The method of this invention combines single-stage rapid temperature programming with segmented control of the carrier gas flow rate within the chromatographic column, effectively separating acrolein, propionaldehyde, and acetone, and accurately quantifying the acrolein content in the liquid phase product of the propylene oxidation reaction. The heating rate reaches 30-40℃ / min, while the carrier gas flow rate is controlled at 0.4-0.6 mL / min and held for 11-14 min. Then, the column flow rate is increased to 2.2-2.5 mL / min at a rate of 3.8-4.0 mL / min and held for 2-3 min. This rapid heating simultaneously achieves effective separation of the target product acrolein from other compounds. Furthermore, the stable isobutanol is selected as an internal standard, and the internal standard quantification method using a calibration curve ensures stable, repeatable, and precise results. The method is simple, rapid, and practical, enabling rapid and accurate analysis of acrolein content in the acrolein synthesis process. Attached Figure Description

[0039] Figure 1 This is the chromatogram corresponding to S4 in Example 1;

[0040] Figure 2 This is the chromatogram corresponding to S5 in Example 1;

[0041] Figure 3 The chromatogram is for Comparative Example 1;

[0042] Figure 4 The chromatogram for Comparative Example 2 is shown below.

[0043] Figure 5 The chromatogram is for Comparative Example 3;

[0044] Figure 6 The chromatogram is for Comparative Example 4;

[0045] Figure 7 The chromatogram is for Comparative Example 5;

[0046] Figure 8 The chromatogram for Comparative Example 6 is shown below.

[0047] Figure 9 This is the chromatogram of Comparative Example 7. Detailed Implementation

[0048] To enable those skilled in the art to more clearly understand the technical solutions described in this invention, the following embodiments are provided for illustration. It should be noted that the following embodiments do not constitute a limitation on the scope of protection claimed by this invention.

[0049] Unless otherwise specified, the raw materials, reagents or devices used in the following examples are available from conventional commercial sources or can be obtained by existing known methods.

[0050] Example 1 A method for determining the acrolein content in the liquid phase product of propylene oxidation reaction by gas chromatography includes the following steps: S1. Chromatographic conditions: The chromatographic column was a 30m × 0.32mm × 1.8μm WM-1301 (6% cyanopropylphenyl-94% dimethylpolysiloxane) capillary column; the carrier gas was high-purity nitrogen (99.99% by mass); the detector was a flame ionization detector (FID); the initial column temperature was 48℃, held for 12 min, then increased to 180℃ at a rate of 35℃ / min, held for 1 min; the initial column flow rate was 0.6mL / min, held for 14 min, then increased to 2.5mL / min at a rate of 4.0mL / min, held for 2 min; the vaporization chamber temperature was 200℃, the detector temperature was 250℃, and split injection was used with a split ratio of 10:1. S2. Preparation of calibration curve solution: Weigh acrolein standard and internal standard isobutanol into five 10mL volumetric flasks according to the mass shown in Table 2, accurate to 0.0001g, then add deionized water to 5g, shake well and set aside to obtain standard solution; Table 2: Sample weight of acrolein standard and internal standard isobutanol

[0051] S3. Construction of calibration curve: Inject 0.2 μL of the standard solution prepared in step S2 into a 1 μL microsyringe. Measure the peak areas of acrolein and the internal standard isobutanol under the gas chromatography conditions in step S1. Plot the mass ratio on the x-axis and the peak area ratio on the y-axis to obtain the linear regression equation y = 1.4019x - 0.0068, which serves as the calibration curve. S4. Detection of the test sample: Take the liquid phase product of the propylene oxidation reaction as the test sample. Accurately weigh 5.0512 g of the test sample, accurate to 0.0001 g, into a 10 mL volumetric flask. Then accurately weigh 0.5058 g of the internal standard isobutanol, accurate to 0.0001 g. Inject the sample according to the gas chromatography conditions in step S1, with an injection volume of 0.2 μL. After all components have eluted, analyze the chromatogram (e.g., ...). Figure 1 As shown, the peak area of ​​acrolein in the sample to be tested was 35.7240%, and the peak area of ​​the internal standard was 63.2276%, with a peak area ratio of 0.5650. According to the calculation formula, the content of acrolein in the sample to be tested was W=7.8626%. The calculation formula is as follows: W=(a×A s / A r +b)×M r / M×100%; in: W represents the acrolein content in the sample to be tested; A s This indicates the peak area of ​​acrolein in the sample being tested; A r This indicates the peak area of ​​the internal standard isobutanol in the sample to be tested; M r This indicates the mass of the internal standard isobutanol in the sample to be tested; M represents the mass of the sample to be tested; a and b can be obtained from the linear regression equation y = 1.4019x - 0.0068 in step S3; S5. Preparation of acrolein standard solution to verify results: Accurately weigh 0.3934 g of acrolein, accurate to 0.0001 g, into a 10 mL volumetric flask. Add deionized water to a final volume of 5.0121 g, accurate to 0.0001 g. At this point, the acrolein content W = 7.8490%. Then accurately weigh 0.5043 g of the internal standard isobutanol, accurate to 0.0001 g, into the same 10 mL volumetric flask to obtain the standard solution. Inject the solution according to the gas chromatography conditions in step S1, with an injection volume of 0.2 μL. After all components have eluted, analyze the chromatogram (e.g., ...). Figure 2As shown, the peak area of ​​acrolein in the test sample (standard solution) is 35.4133%, and the peak area of ​​the internal standard is 62.5068%. The peak area ratio of the two is 0.5666, which is similar to the peak area ratio of the test sample in S4. According to the calculation formula, the content of acrolein in the test sample is W=7.9237%, which is similar to the actual value of the acrolein standard solution mentioned above.

[0052] Example 2 A method for determining the acrolein content in the liquid phase product of propylene oxidation reaction by gas chromatography includes the following steps: S1. Chromatographic conditions: The chromatographic column was a 30m × 0.32mm × 1.8μm WM-1301 (6% cyanopropylphenyl-94% dimethylpolysiloxane) capillary column; the carrier gas was high-purity nitrogen (99.99% by mass); the detector was a flame ionization detector (FID); the initial column temperature was 48℃, held for 12 min, then increased to 180℃ at a rate of 35℃ / min, held for 1 min; the initial column flow rate was 0.6mL / min, held for 14 min, then increased to 2.5mL / min at a rate of 4.0mL / min, held for 2 min; the vaporization chamber temperature was 200℃, the detector temperature was 250℃, and split injection was used with a split ratio of 10:1. S2. Preparation of calibration curve solution: Weigh acrolein standard and internal standard isobutanol into five 10mL volumetric flasks according to the mass shown in Table 2, accurate to 0.0001g, then add deionized water to 5g, shake well and set aside to obtain standard solution; Table 2: Sample weight of acrolein standard and internal standard isobutanol

[0053] S3. Construction of calibration curve: Inject 0.2 μL of the standard solution prepared in step S2 into a 1 μL microsyringe. Measure the peak areas of acrolein and the internal standard isobutanol under the gas chromatography conditions in step S1. Plot the mass ratio on the x-axis and the peak area ratio on the y-axis to obtain the linear regression equation y = 1.4019x - 0.0068, which serves as the calibration curve. S4. Detection of the sample to be tested: Take the liquid phase product of propylene oxidation reaction as the sample to be tested. Accurately weigh 5.0277 g of the sample to be tested, accurate to 0.0001 g, into a 10 mL volumetric flask. Then accurately weigh 0.4957 g of the internal standard isobutanol, accurate to 0.0001 g, into the same 10 mL volumetric flask. Inject the sample into the gas chromatography under the conditions described in step S1, with an injection volume of 0.2 μL. After the components have completely eluted, the chromatogram shows that the peak area of ​​acrolein in the sample to be tested is 46.0661%, and the peak area of ​​the internal standard is 52.7249%, with a peak area ratio of 0.8737. According to the calculation formula, the content of acrolein in the sample to be tested is W = 12.0092%. The calculation formula is as follows: W=(a×A s / A r +b)×M r / M×100%; in: W represents the acrolein content in the sample to be tested; A s This indicates the peak area of ​​acrolein in the sample being tested; A r This indicates the peak area of ​​the internal standard isobutanol in the sample to be tested; M r This indicates the mass of the internal standard isobutanol in the sample to be tested; M represents the mass of the sample to be tested; a and b can be obtained from the linear regression equation y = 1.4019x - 0.0068 in step S3; S5. Preparation of acrolein standard solution to verify results: Accurately weigh 0.5985 g of acrolein, accurate to 0.0001 g, into a 10 mL volumetric flask. Add deionized water to a final volume of 5.0063 g, accurate to 0.0001 g. At this point, the acrolein content W = 11.9351%. Then accurately weigh 0.5063 g of the internal standard isobutanol, accurate to 0.0001 g, into the same 10 mL volumetric flask to obtain the standard solution. Follow the gas chromatography procedure in step S1. The chromatographic injection conditions were as follows: injection volume was 0.2 μL. After the components had completely eluted, the chromatogram showed that the peak area of ​​acrolein in the test sample (standard solution) was 44.9756%, and the peak area of ​​the internal standard was 54.2757%, with a peak area ratio of 0.8188. This peak area ratio was similar to that of the test sample in S4. Based on the calculation formula, the acrolein content in the test sample was calculated to be W = 11.6797%, which was similar to the actual value of the acrolein standard solution.

[0054] Comparative Example 1

[0055] Compared with Example 1, the only difference in Comparative Example 1 is that the liquid phase product of the propylene oxidation reaction was directly taken as the sample to be tested and separated according to the following chromatographic conditions.

[0056] The chromatographic conditions for Comparative Example 1 are as follows:

[0057] 0.2 μL of the sample was injected using a 1 μL microsyringe. The chromatographic column was a 30 m × 0.32 mm × 1.8 μm WM-1301 (6% cyanopropylphenyl-94% dimethyl polysiloxane) capillary column. The carrier gas was high-purity nitrogen (99.99% by mass). The detector was a flame ionization detector (FID). The initial column temperature was 48 °C, held for 12 min, and then increased to 180 °C at a rate of 35 °C / min, held for 1 min. The initial column flow rate was 0.6 mL / min, held for 19 min. The temperature of the vaporization chamber was 200 °C, and the detector temperature was 250 °C. Split injection was used with a split ratio of 10:1.

[0058] The compounds were isolated, and the collection time was 18.92 min.

[0059] The chromatogram obtained from Comparative Example 1 is as follows: Figure 3 ( Figure 3 The horizontal axis represents time, and the vertical axis represents current (pA), as shown in the diagram. Figure 3 As can be seen, the chromatogram of the sample tested has seven peaks: acetaldehyde, acrolein, propionaldehyde, acetone, isobutanol, acetic acid, and acrylic acid. From... Figure 3 It can also be seen that the content of acrolein is 25.3220%, the content of propionaldehyde is 1.7355%, and the content of acetone is 5.1626%.

[0060] Comparative Example 2

[0061] Compared with Example 1, the only difference in Comparative Example 2 is that the liquid phase product of the propylene oxidation reaction was directly taken as the sample to be tested and separated according to the following chromatographic conditions.

[0062] The chromatographic conditions for Comparative Example 2 are as follows:

[0063] 0.2 μL of the sample was injected using a 1 μL microsyringe. The chromatographic column was a 30 m × 0.32 mm × 1.8 μm WM-1301 (6% cyanopropylphenyl-94% dimethyl polysiloxane) capillary column. The carrier gas was high-purity nitrogen (99.99% by mass). The detector was a flame ionization detector (FID). The initial column temperature was 48 °C, held for 12 min, and then increased to 180 °C at a rate of 35 °C / min, held for 1 min. The initial column flow rate was 0.6 mL / min, held for 17 min. The temperature of the vaporization chamber was 200 °C, and the detector temperature was 250 °C. Split injection was used with a split ratio of 10:1.

[0064] The compounds were isolated, and the acquisition time was 16.29 min.

[0065] The chromatogram obtained from Comparative Example 2 is as follows: Figure 4 As shown. From Figure 4 As can be seen, the chromatogram of the sample tested has six peaks: acetaldehyde, acrolein, propionaldehyde, acetone, isobutanol, and acetic acid. No peak for acrylic acid was observed. From... Figure 4 It can also be seen that the content of acrolein is 27.0938%, the content of propionaldehyde is 1.8545%, and the content of acetone is 5.2780%.

[0066] Comparative Example 3

[0067] Compared with Example 1, the only difference in Comparative Example 3 is that the liquid phase product of the propylene oxidation reaction was directly taken as the sample to be tested and separated according to the following chromatographic conditions.

[0068] The chromatographic conditions for Comparative Example 3 are as follows:

[0069] 0.2 μL of the sample was injected using a 1 μL microsyringe. The chromatographic column was a 30 m × 0.32 mm × 1.8 μm WM-1301 (6% cyanopropylphenyl-94% dimethyl polysiloxane) capillary column. The carrier gas was high-purity nitrogen (99.99% by mass). The detector was a flame ionization detector (FID). The initial column temperature was 48 °C, held for 12 min, and then increased to 180 °C at a rate of 35 °C / min, held for 1 min. The initial column flow rate was 0.6 mL / min, held for 14 min, and then increased to 2.5 mL / min at a rate of 4 mL / min, held for 2 min. The vaporization chamber temperature was 200 °C, and the detector temperature was 250 °C. Split injection was used with a split ratio of 10:1.

[0070] The compounds were isolated, and the acquisition time was 16.29 min.

[0071] The chromatogram obtained in Comparative Example 3 is as follows: Figure 5 As shown. From Figure 5 As can be seen, the chromatogram of the sample to be tested has 7 peaks, namely acetaldehyde, acrolein, propionaldehyde, acetone, isobutanol, acetic acid, and acrylic acid. Comparing with Comparative Example 2, it can be found that acrylic acid was detected.

[0072] from Figure 5 It can also be seen that the content of acrolein is 26.4254%, the content of propionaldehyde is 1.7970%, and the content of acetone is 5.1905%.

[0073] Comparative Example 4

[0074] Compared with Example 1, the only difference in Comparative Example 4 is that the liquid phase product of the propylene oxidation reaction was directly taken as the sample to be tested and separated according to the following chromatographic conditions.

[0075] The chromatographic conditions for Comparative Example 4 are as follows:

[0076] 0.2 μL of the sample was injected using a 1 μL microsyringe. The chromatographic column was a 30 m × 0.32 mm × 1.8 μm WM-1301 (6% cyanopropylphenyl-94% dimethyl polysiloxane) capillary column. The carrier gas was high-purity nitrogen (99.99% by mass). The detector was a flame ionization detector (FID). The initial column temperature was 48 °C, held for 12 min, and then increased to 180 °C at a rate of 35 °C / min, held for 1 min. The initial column flow rate was 0.6 mL / min, held for 10 min, and then increased to 2.5 mL / min at a rate of 4 mL / min, held for 6 min. The temperature of the vaporization chamber was 200 °C, and the detector temperature was 250 °C. Split injection was used with a split ratio of 10:1.

[0077] The compounds were isolated, and the acquisition time was 16.29 min.

[0078] The chromatogram obtained in Comparative Example 4 is as follows: Figure 6 As shown. From Figure 6 As can be seen, the chromatogram of the sample to be tested has 7 peaks, namely acetaldehyde, acrolein, propionaldehyde, acetone, isobutanol, acetic acid, and acrylic acid. Compared with Comparative Example 3, it was found that a small portion of the propionaldehyde peak area was included in the acrolein peak area.

[0079] from Figure 6 It can also be seen that the content of acrolein is 26.2517%, the content of propionaldehyde is 1.6811%, and the content of acetone is 5.1773%.

[0080] Comparative Example 5

[0081] Compared with Example 1, the only difference in Comparative Example 5 is that the liquid phase product of the propylene oxidation reaction was directly taken as the sample to be tested and separated according to the following chromatographic conditions.

[0082] The chromatographic conditions for Comparative Example 5 are as follows:

[0083] 0.2 μL of the sample was injected using a 1 μL microsyringe. The chromatographic column was a 30 m × 0.32 mm × 1.8 μm WM-1301 (6% cyanopropylphenyl-94% dimethyl polysiloxane) capillary column. The carrier gas was high-purity nitrogen (99.99% by mass). The detector was a flame ionization detector (FID). The initial column temperature was 48 °C, held for 12 min, and then increased to 180 °C at a rate of 35 °C / min, held for 1 min. The initial column flow rate was 0.6 mL / min, held for 6 min, and then increased to 2.5 mL / min at a rate of 4 mL / min, held for 10 min. The temperature of the vaporization chamber was 200 °C, and the detector temperature was 250 °C. Split injection was used with a split ratio of 10:1.

[0084] The compounds were isolated, and the acquisition time was 16.29 min.

[0085] The chromatogram obtained in Comparative Example 5 is as follows: Figure 7 As shown. From Figure 7 As can be seen, the chromatogram of the sample to be tested has 7 peaks, namely acetaldehyde, acrolein, propionaldehyde, acetone, isobutanol, acetic acid, and acrylic acid. Compared with Comparative Examples 3-4, it was found that more and more propionaldehyde was counted as acrolein in the peak area of ​​acrolein.

[0086] from Figure 7 It can also be seen that the content of acrolein is 24.6488%, the content of propionaldehyde is 1.0859%, and the content of acetone is 5.1476%.

[0087] Comparative Example 6

[0088] Compared with Example 1, the only difference in Comparative Example 6 is that the liquid phase product of the propylene oxidation reaction was directly taken as the sample to be tested and separated according to the following chromatographic conditions.

[0089] The chromatographic conditions for Comparative Example 6 are as follows:

[0090] 0.2 μL of the sample was injected using a 1 μL microsyringe. The chromatographic column was a 30 m × 0.32 mm × 1.8 μm WM-1301 (6% cyanopropylphenyl-94% dimethyl polysiloxane) capillary column. The carrier gas was high-purity nitrogen (99.99% by mass). The detector was a flame ionization detector (FID). The initial column temperature was 48 °C, held for 12 min, and then increased to 180 °C at a rate of 35 °C / min, held for 1 min. The initial column flow rate was 0.6 mL / min, held for 1 min, and then increased to 2.5 mL / min at a rate of 4 mL / min, held for 15 min. The temperature of the vaporization chamber was 200 °C, and the detector temperature was 250 °C. Split injection was used with a split ratio of 10:1.

[0091] The compounds were isolated, and the acquisition time was 16.29 min.

[0092] The chromatogram obtained from Comparative Example 6 is as follows: Figure 8 As shown. From Figure 8 As can be seen, the chromatogram of the sample to be tested has 7 peaks, namely acetaldehyde, acrolein, propionaldehyde, acetone, isobutanol, acetic acid, and acrylic acid. Compared with Comparative Examples 3-5, it was found that most of the propionaldehyde was counted as acrolein in the peak area calculation.

[0093] from Figure 8 It can also be seen that the content of acrolein is 25.1533%, the content of propionaldehyde is 0.4358%, and the content of acetone is 5.0506%.

[0094] Comparative Example 7

[0095] Compared with Example 1, the only difference in Comparative Example 7 is that the liquid phase product of the propylene oxidation reaction was directly taken as the sample to be tested and separated according to the following chromatographic conditions.

[0096] The chromatographic conditions for Comparative Example 7 are as follows:

[0097] 0.2 μL of the sample was injected using a 1 μL microsyringe. The chromatographic column was a 30 m × 0.32 mm × 1.8 μm WM-1301 (6% cyanopropylphenyl-94% dimethyl polysiloxane) capillary column. The carrier gas was high-purity nitrogen (99.99% by mass). The detector was a flame ionization detector (FID). The initial column temperature was 48 °C, held for 12 min, and then increased to 180 °C at a rate of 35 °C / min, held for 1 min. The initial column flow rate was 2.5 mL / min, which was kept constant. The test time was 16.29 min. The temperature of the vaporization chamber was 200 °C, and the detector temperature was 250 °C. Split injection was used with a split ratio of 10:1.

[0098] The dipole moments of acrolein, propionaldehyde, and acetone are close, indicating that their molecular polarities are similar. Therefore, effective separation of acrolein, propionaldehyde, and acetone is very difficult when using gas chromatography. If the separation of propionaldehyde is neglected, its chromatographic peak may be masked by that of acrolein, making accurate quantification of acrolein difficult.

[0099] The chromatogram obtained in Comparative Example 7 is as follows: Figure 9 As shown. From Figure 9 As can be seen, the chromatogram of the sample to be tested has 5 peaks, namely acetaldehyde, acrolein, acetone, isobutanol, and acrylic acid.

[0100] from Figure 9 It can also be seen that the content of acrolein is 28.9762% and the content of acetone is 4.6354%.

[0101] Examples 1 and 2 above are used to verify the accuracy of the method of the present invention: first, the acrolein content in the sample to be tested is calculated according to the calibration curve, and then a solution is prepared according to the calculation result to verify whether the test result is accurate. For example, the calculated result of Example 2 is 12.0092%, and a solution of 11.9351% is prepared for testing, and the result obtained is 11.6797%. By comparing the results, 12.0092% and 11.6797% are similar, indicating that the test result is reliable.

[0102] Comparative Examples 1 to 7 are used to illustrate that different test conditions may lead to incomplete separation of acrolein, propionaldehyde, and acetone, affecting the reliability of the test results.

[0103] The method of this invention has been described through specific embodiments and is not intended to limit the invention. Those skilled in the art can make appropriate modifications or equivalent substitutions of some technical features based on the content of this invention to achieve other corresponding objectives. Such changes do not depart from the scope of this invention, and any modifications, substitutions, or improvements made are considered to be included within the protection scope of this invention.

Claims

1. A method for determining the acrolein content in the liquid phase product of propylene oxidation reaction by gas chromatography, characterized in that, Includes the following steps: S1. Chromatographic conditions control: The chromatographic column used is a cyanopropylphenyl-dimethylpolysiloxane capillary column, the carrier gas is nitrogen, the initial column flow rate is 0.4-0.6 mL / min, held for 11-14 min, and then the column flow rate is increased to 2.2-2.5 mL / min at a rate of 3.8-4.0 mL / min and held for 2-3 min; split injection is used. S2. Preparation of calibration curve solution: Weigh acrolein standard and internal standard isobutanol into multiple volumetric flasks according to the mass shown in Table 2, then add deionized water, shake well and set aside to use to obtain standard solution. Table 2: Sample weight of acrolein standard and internal standard isobutanol S3. Construction of the calibration curve: Inject the standard solution prepared in step S2 into the syringe, and determine the peak areas of acrolein and the internal standard isobutanol according to the gas chromatography conditions. Plot the mass ratio as the abscissa and the peak area ratio as the ordinate, and find the linear regression equation, denoted as y=ax+b, as the calibration curve. S4. Detection of the test sample: Take the liquid phase product of the propylene oxidation reaction as the test sample. Accurately weigh the test sample and place it in a volumetric flask. Then weigh the internal standard isobutanol and add it to the volumetric flask. Add deionized water, and then inject the sample according to the gas chromatography conditions in step S1. After all components have eluted, obtain the peak area ratio of the test sample and the internal standard from the chromatogram, which is A. s / A r The mass ratio of the two components is obtained based on the calibration curve in step S3, and then the acrolein content W in the sample to be tested is calculated using the following formula: W=(a×A s / A r +b)×M r / M×100%; in: W represents the acrolein content in the sample to be tested; A s This indicates the peak area of ​​acrolein in the sample being tested; A r This indicates the peak area of ​​the internal standard isobutanol in the sample to be tested; M r This indicates the mass of the internal standard isobutanol in the sample to be tested; M represents the mass of the sample to be tested; a and b can be obtained from the linear regression equation in step S3; S5. Prepare acrolein standard solution to verify the test results: Weigh acrolein and place it in a volumetric flask, then add deionized water to obtain an acrolein standard solution. At this time, the acrolein content in the acrolein standard solution is similar to the acrolein content W in step S4. Weigh the internal standard isobutanol and add it to the volumetric flask. Then, inject the sample according to the gas chromatography conditions in step S1. After the components have completely eluted, obtain the peak area of ​​acrolein in the acrolein standard solution, the peak area of ​​the internal standard, and the ratio of their peak areas from the chromatogram. Compare the values ​​obtained in step S4 to verify the reliability of the test results.

2. The determination method according to claim 1, characterized in that, In step S1, the initial column flow rate is 0.6 mL / min, held for 14 min, and then the column flow rate is increased to 2.5 mL / min at a rate of 4.0 mL / min and held for 2 min.

3. The determination method according to claim 1, characterized in that, The capillary column contains 6% cyanopropylphenyl and 94% dimethylpolysiloxane by mass, respectively.

4. The determination method according to claim 1, characterized in that, In step S1, the detector used is a hydrogen flame ionization detector.

5. The determination method according to claim 1, characterized in that, In step S1, the initial column temperature is 45-48℃, held for 8-9 minutes, and then increased to 170-180℃ at a rate of 30-40℃ / min, held for 1-2 minutes.

6. The determination method according to claim 1, characterized in that, In step S1, the temperature of the vaporization chamber is 190-200℃, and the temperature of the detector is 245-250℃.

7. The determination method according to claim 1, characterized in that, In step S1, the split ratio for split injection is 10:

1.

8. The determination method according to claim 1, characterized in that, In step S4, the liquid phase product of the propylene oxidation reaction is taken as the test sample. The test sample is accurately weighed to 0.0001 g and placed in a 10 mL volumetric flask. The internal standard isobutanol is then accurately weighed to 0.0001 g and placed in the same 10 mL volumetric flask. Deionized water is then added to 5 g to 0.0001 g and placed in the same 10 mL volumetric flask. The sample is then injected into the gas chromatographic flask according to the conditions of step S1, with an injection volume of 0.2 μL.

9. The determination method according to claim 1, characterized in that, In step S5, acrolein is accurately weighed to a precision of 0.0001 g and placed in a 10 mL volumetric flask. Deionized water is then added to a final volume of 5 g, accurate to a precision of 0.0001 g, and placed in the same 10 mL volumetric flask. At this point, the acrolein content in the acrolein standard solution is similar to the acrolein content W in step S4. The internal standard isobutanol is then accurately weighed to a precision of 0.0001 g and placed in the same 10 mL volumetric flask. The sample is then injected according to gas chromatography conditions, with an injection volume of 0.2 μL.

10. The application of the determination method according to any one of claims 1-9 in the fields of medicine, food or cosmetics.

Images