Analysis method and analysis system for ethylene glycol byproduct mixed alcohol

Abstract

The invention belongs to the technical field of analysis and detection, and relates to an analysis method and an analysis system of ethylene glycol by-product mixed alcohol, the analysis method comprises the following steps: S1, preparing a corresponding reference solution and a standard mixed alcohol solution according to a to-be-analyzed component in the ethylene glycol by-product mixed alcohol; s2, for the reference substance solution and the standard mixed alcohol solution, constructing a standard curve model corresponding to each component through gas chromatography; s3, collecting by-products in ethylene glycol production in real time, and filtering; according to the method, peak areas corresponding to components to be analyzed in the mixed alcohol sample are obtained and then substituted into respective standard curve models respectively, and the content of the components to be analyzed in the mixed alcohol sample is obtained. According to the method, the standard curve model is constructed, and the mixed alcohol is pretreated, so that the content of multiple components in the mixed alcohol is analyzed and detected, the analysis time is shortened, the analysis cost is reduced, and the analysis accuracy and sensitivity are improved.

Description

Technical Field

[0001] The invention belongs to the technical field of analysis and detection, and relates to an analysis method and an analysis system for ethylene glycol byproduct mixed alcohol. Background Art

[0002] Mixed alcohols are often produced as byproducts in the production of ethylene glycol. The components of these mixed alcohols are relatively complex, mainly including methylal, methyl formate, methanol, ethanol, dimethyl carbonate, dimethyl oxalate, methyl glycolate, ethylene glycol, 1,2-propylene glycol, 1,2-butylene glycol, 1,2-hexanediol, etc. At present, these mixed alcohols are generally sold as waste. Before they are sold, the content of the components needs to be analyzed, because if the content of the components is not analyzed, the mixed alcohols can only be sold based on the water content, which will reduce the sales price and reduce the revenue.

[0003] There are many components in mixed alcohols, and different components require different analysis methods. For example, ethanol can be determined by distillation. The distillation method mainly separates the ethanol component to be detected through the distillation process, and then determines the ethanol content by measuring the relative density of the components after distillation. However, for samples with complex components, this method may require more complex pretreatment steps to accurately determine the content of each component, resulting in long processing time and high cost. Another example is the Chinese invention patent with announcement number CN114814049B, which discloses a method for analyzing dimethyl oxalate. Acetonitrile is used as a solvent to dissolve solid dimethyl oxalate so that it can be directly injected into a gas chromatography column with an automatic sampler, and the purity and impurities of dimethyl oxalate are detected by gas chromatography separation. The Chinese invention patent with announcement number CN106814144B discloses a method for measuring the content of dimethyl sulfate in dimethyl fumarate. A quantitative analysis method, in which a secondary amine is used as a derivatizing agent to form a derivative with dimethyl sulfate in dimethyl fumarate, and then the content of the derivative is determined by high performance liquid chromatography-mass spectrometry, thereby obtaining the content of dimethyl sulfate in dimethyl fumarate; a Chinese invention patent with publication number CN105699499A discloses a quantitative analysis method, in which a 1,3-propanediol fermentation broth from which Klebsiella and high protein are removed by centrifugation is diluted with a carrier liquid and filtered to obtain a sample to be tested; the chromatographic column is a ligand exchange column, a differential refractive index detector is used, and the ligand exchange column is activated before injection; the obtained sample to be tested is injected into the activated ligand exchange column for detection; the contents of 1,3-propanediol, glycerol, acetic acid, ethanol, 2,3-butanediol, lactic acid and succinic acid are calculated by an external standard method.

[0004] In summary, in the current analysis methods, each component corresponds to a specific analysis method. However, the components in the ethylene glycol by-product mixed alcohol are complex. If multiple methods are used to analyze the component contents in the mixed alcohol separately, the analysis time will be long and the analysis cost will be high. In addition, since the ethylene glycol by-product mixed alcohol also contains impurities, the analysis accuracy and sensitivity are reduced. Summary of the invention

[0005] In view of the technical problems of long analysis time, high cost and reduced accuracy and sensitivity in the existing analysis process, the present invention provides an analysis method and analysis system for ethylene glycol by-product mixed alcohol.

[0006] The invention realizes the analysis and detection of the contents of multiple components in the mixed alcohol by constructing a standard curve model of the mixed alcohol components and filtering the mixed alcohol, thereby shortening the analysis time, reducing the analysis cost, and improving the analysis accuracy and sensitivity.

[0007] In order to achieve the above object, the technical solution adopted by the present invention is:

[0008] An analytical method for ethylene glycol byproduct mixed alcohol comprises the following steps:

[0009] S1. Solution preparation

[0010] According to the components to be analyzed in the ethylene glycol byproduct mixed alcohol, prepare corresponding reference solution and standard mixed alcohol solution;

[0011] There are multiple components to be analyzed, and there are multiple reference solutions, which are prepared from the corresponding components to be analyzed; the standard mixed alcohol solution refers to a mixed solution containing multiple components to be analyzed at the same time, and the content of each component to be analyzed in the standard mixed alcohol solution is known;

[0012] S2. Constructing a standard curve model

[0013] S2.1. For the above-mentioned multiple reference solution, the peak time of each chromatographic peak on the chromatogram of each reference solution is collected by gas chromatography in turn, that is, the peak time corresponding to each component is obtained;

[0014] S2.2, obtaining a standard mixed chromatogram of the standard mixed alcohol solution by gas chromatography, and qualitatively analyzing each chromatographic peak on the standard mixed chromatogram according to the peak elution time in step S2.1 to confirm the components corresponding to each chromatographic peak on the standard mixed chromatogram;

[0015] S2.3, then quantitatively analyze each chromatographic peak on the standard mixed chromatogram to obtain the peak area of ​​each chromatographic peak, that is, obtain the peak area corresponding to each component;

[0016] S2.4, changing the content of each component to prepare a reference solution and a standard mixed alcohol solution respectively, and according to the method of step S2.1 to step S2.3, obtaining the corresponding peak area of ​​each component at different known contents;

[0017] S2.5. For each component, use the known content as the horizontal axis and the peak area as the vertical axis to draw a curve and perform normalization to construct a standard curve model corresponding to each component;

[0018] S3. Actual sample testing

[0019] S3.1. Real-time collection of by-products in ethylene glycol production, i.e. mixed alcohol samples;

[0020] S3.2, filtering the mixed alcohol sample;

[0021] S3.3. Referring to the method of step 2.2 and step S2.3, obtain the peak area corresponding to the component to be analyzed in the mixed alcohol sample, and then substitute it into the respective standard curve models to obtain the content of the component to be analyzed in the mixed alcohol sample.

[0022] It is further defined that in step S1, the components to be analyzed are methylal, methanol, dimethyl carbonate, dimethyl oxalate, ethylene glycol, 1.2-hexanediol, ethylene carbonate, methyl formate, ethanol, methyl glycolate, 1.2-propylene glycol, 1.2-butylene glycol, 1.4-butylene glycol and triethylene glycol.

[0023] Further defined, in step S2, the conditions of gas chromatography are:

[0024] The chromatographic column was DB-WAX with dimensions of 60 m × 320 μm × 0.25 μm;

[0025] The temperature program is as follows: Gradient 1: heating rate is not more than 10°C / min, temperature setting is not higher than 100°C; Gradient 2: heating rate is not more than 20°C / min, temperature setting is not higher than 240°C, and temperature holding time is not less than 8 minutes.

[0026] It is further defined that in step S3, purification is performed using a water filter membrane.

[0027] It is further defined that the water filter membrane has a pore size of 0.45 μm.

[0028] It is further defined that in step S3, it is necessary to determine whether the collected mixed alcohol sample contains crystal particles. If it contains crystal particles, an organic reagent needs to be added to dissolve the crystal particles.

[0029] It is further defined that the organic reagent is acetonitrile.

[0030] An analysis system for realizing the analysis method of ethylene glycol byproduct mixed alcohol, the analysis system comprising a liquid preparation unit, a gas chromatography analysis unit, a sample collection unit and a pretreatment unit;

[0031] The pretreatment unit is used to filter the collected mixed alcohol sample;

[0032] The liquid preparation unit is used to prepare each reference substance solution and each standard mixed alcohol solution;

[0033] The gas chromatography analysis unit is used to detect and obtain the chromatograms corresponding to each reference solution, each standard mixed alcohol solution and the mixed alcohol sample, and to perform qualitative and quantitative analysis on each chromatogram to obtain the peak area of ​​each reference solution;

[0034] The model building unit is used to build a standard curve model corresponding to each reference substance according to the known content and the peak area of ​​each reference substance;

[0035] The sample collection unit is used to collect mixed alcohol samples from ethylene glycol production.

[0036] It is further defined that the pretreatment unit is a filter screen, the filter screen is circular, and the mesh diameter of the filter screen is 0.45 μm.

[0037] The beneficial effects of the present invention are:

[0038] 1. The present invention filters the mixed alcohol by pretreatment, and realizes the analysis and detection of multiple components in the mixed alcohol by constructing a standard curve model of the mixed alcohol components, thereby shortening the analysis time, reducing the analysis cost, and improving the analysis accuracy and sensitivity.

[0039] 2. The present invention can enhance the separation effect by setting chromatographic conditions, such as temperature program, carrier gas flow rate, heating rate, temperature holding time and post-operation time, so as to effectively separate the components in the mixed alcohol, ensure the order of peaks, avoid the mutual influence of each component, further improve the accuracy and sensitivity of the analysis, and solve the problem of separation of complex mixtures.

[0040] 3. In the present invention, the collected mixed alcohol sample is filtered to reduce the interference of impurities and improve the analysis sensitivity.

[0041] 4. The analysis method provided by the present invention has small differences in analysis results, good consistency, and high accuracy of analysis results.

[0042] 5. The analysis system provided by the present invention has a simple structure and is easy to build, and is easy to implement batch analysis and detection of mixed alcohols, thereby improving the analysis efficiency of samples. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 The chromatogram corresponding to the standard mixed alcohol solution at the first component content in Example 1;

[0044] Figure 2 The chromatogram corresponding to the standard mixed alcohol solution at the second component content in Example 1;

[0045] Figure 3 This is the chromatogram corresponding to the standard mixed alcohol solution at the third component content in Example 1. DETAILED DESCRIPTION

[0046] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Therefore, the following detailed description of the embodiments of the present invention provided in the drawings is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0047] The present invention provides a method for analyzing ethylene glycol byproduct mixed alcohol, comprising the following steps:

[0048] S1. Solution preparation

[0049] According to the components to be analyzed in the ethylene glycol byproduct mixed alcohol, the corresponding reference solution and standard mixed alcohol solution are prepared.

[0050] There are multiple components to be analyzed, and there are multiple reference solutions, which are prepared from the corresponding components to be analyzed; the standard mixed alcohol solution refers to a mixed solution containing multiple components to be analyzed at the same time, and the content of each component to be analyzed in the standard mixed alcohol solution is known.

[0051] Preferably, in step S1 of the present invention, the components to be analyzed include methylal, methanol, dimethyl carbonate, dimethyl oxalate, ethylene glycol, 1.2-hexanediol, ethylene carbonate, methyl formate, ethanol, methyl glycolate, 1.2-propylene glycol, 1.2-butanediol, 1.4-butanediol and triethylene glycol.

[0052] In the present invention, the number of reference solutions is determined according to the number of components to be actually analyzed. If several components need to be analyzed, several reference solutions are prepared accordingly, and each reference solution contains only one component to be analyzed.

[0053] In the present invention, the number of components contained in the standard mixed alcohol solution is determined according to the number of components to be analyzed. If several components need to be analyzed, the standard mixed alcohol solution will contain several components at the same time.

[0054] S2. Constructing a standard curve model

[0055] S2.1. For the above-mentioned multiple reference solution, the peak time of each chromatographic peak on the chromatogram of each reference solution is collected by gas chromatography in turn, that is, the peak time corresponding to each component is obtained;

[0056] S2.2, obtaining a standard mixed chromatogram of the standard mixed alcohol solution by gas chromatography, and qualitatively analyzing each chromatographic peak on the standard mixed chromatogram according to the peak elution time in step S2.1 to confirm the components corresponding to each chromatographic peak on the standard mixed chromatogram;

[0057] S2.3, then quantitatively analyze each chromatographic peak on the standard mixed chromatogram to obtain the peak area of ​​each chromatographic peak, that is, obtain the peak area corresponding to each component;

[0058] S2.4, changing the content of each component to prepare a reference solution and a standard mixed alcohol solution respectively, and according to the method of step S2.1 to step S2.3, obtaining the corresponding peak area of ​​each component at different known contents;

[0059] S2.5. For each component, use the known content as the horizontal axis and the peak area as the vertical axis to draw a curve and perform normalization to construct a standard curve model corresponding to each component;

[0060] S3. Actual sample testing

[0061] S3.1. Real-time collection of by-products in ethylene glycol production, i.e. mixed alcohol samples;

[0062] S3.2, filtering the mixed alcohol sample;

[0063] S3.3. Referring to the method of step 2.2 and step S2.3, obtain the peak area corresponding to the component to be analyzed in the mixed alcohol sample, and then substitute it into the respective standard curve models to obtain the content of the component to be analyzed in the mixed alcohol sample.

[0064] Preferably, in the present invention, it is necessary to detect the contents of 14 components including methylal, methanol, dimethyl carbonate, dimethyl oxalate, ethylene glycol, 1.2-hexanediol, ethylene carbonate, methyl formate, ethanol, methyl glycolate, 1.2-propylene glycol, 1.2-butanediol, 1.4-butanediol and triethylene glycol in the actual mixed alcohol sample, and therefore 14 reference solutions are prepared respectively; then, 12 chromatograms of the reference solutions are obtained by gas chromatography of the 14 reference solutions, and the peak times corresponding to the chromatographic peaks on the chromatograms of the 14 reference solutions are collected, that is, the peak times corresponding to the 14 components.

[0065] In the present invention, a standard mixed alcohol solution containing 14 components is prepared at the same time, and the content (amount) of each component is known. The standard mixed chromatogram is obtained by gas chromatography, and the chromatographic peaks on the standard mixed chromatogram are qualitatively analyzed according to the peak elution times corresponding to the 12 components, the components corresponding to the chromatographic peaks are confirmed, and quantitative analysis is performed to obtain the peak areas of each chromatographic peak, that is, the peak area corresponding to each component is obtained.

[0066] In order to improve the accuracy of analysis, the content of each component in the standard mixed alcohol solution is changed to obtain standard mixed alcohol solutions with different known contents. A standard mixed chromatogram is obtained by gas chromatography, and correspondingly multiple standard mixed chromatograms are obtained. Each standard mixed chromatogram is qualitatively and quantitatively analyzed to obtain the peak area corresponding to each component at different contents.

[0067] Further, the known content and corresponding peak area of ​​each component are collected, a curve is drawn, and a standard curve model corresponding to each component is obtained by normalization. In the present invention, a total of 12 standard curve models are obtained.

[0068] In step S2 of the present invention, the conditions of gas chromatography are:

[0069] The chromatographic column is DB-WAX with dimensions of 60m×320μm×0.25μm; the temperature program is: gradient 1: heating rate not greater than 10℃ / min, temperature setting not higher than 100℃; gradient 2: heating rate not greater than 20℃ / min, temperature setting not higher than 240℃, and temperature holding time not less than 8min.

[0070] In step S3 of the present invention, purification is performed using a water filter membrane. Preferably, the water filter membrane has a pore size of 0.45 μm.

[0071] In step S3 of the present invention, it is also necessary to determine whether the collected mixed alcohol sample contains crystal particles. If it contains crystal particles, an organic reagent is added to dissolve the crystal particles. Preferably, the organic reagent is acetonitrile.

[0072] The present invention also provides an analysis system for realizing the analysis method of ethylene glycol byproduct mixed alcohol, the analysis system comprising a liquid preparation unit, a gas chromatography analysis unit, a sample collection unit and a pretreatment unit;

[0073] Pretreatment unit: used for filtering the collected mixed alcohol samples;

[0074] Liquid preparation unit: used to prepare various reference solutions and various standard mixed alcohol solutions;

[0075] Gas chromatography analysis unit: used to detect and obtain the chromatograms corresponding to each reference solution, each standard mixed alcohol solution and the mixed alcohol sample, and to perform qualitative and quantitative analysis on each chromatogram to obtain the peak area of ​​each reference solution;

[0076] Model building unit: used to build a standard curve model corresponding to each reference substance based on the known content and peak area of ​​each reference substance;

[0077] Sample collection unit: used to collect mixed alcohol samples from ethylene glycol production.

[0078] Preferably, the pretreatment unit provided by the present invention is a filter screen, the filter screen is circular, and the mesh diameter of the filter screen is 0.45 μm.

[0079] The analysis method provided by the present invention is described in detail below with reference to specific embodiments.

[0080] It should be noted that, unless otherwise specified, the chemical reagents, medicines, etc. used in the following examples are all conventional products purchased from the market.

[0081] It should be noted that, unless otherwise specified, the operating steps used in the following embodiments are all conventional operating methods in the art.

[0082] Example

[0083] The analysis method of the ethylene glycol byproduct mixed alcohol provided in this embodiment comprises the following steps:

[0084] S1. Solution preparation

[0085] According to the components to be analyzed in the ethylene glycol byproduct mixed alcohol, the corresponding reference solution and standard mixed alcohol solution are prepared.

[0086] In this embodiment, the components to be analyzed are methylal, methanol, dimethyl carbonate, dimethyl oxalate, ethylene glycol, 1.2-hexanediol, ethylene carbonate, methyl formate, ethanol, methyl glycolate, 1.2-propylene glycol, 1.2-butylene glycol, 1.4-butylene glycol and triethylene glycol.

[0087] The contents of each component are shown in Table 1, where the contents refer to mass fractions.

[0088] In the implementation, 14 reference solutions and 1 standard mixed alcohol solution with known content were prepared according to the contents in Table 1.

[0089] Table 1 Content (mass fraction) of each component

[0090] Components content Components content Methylal 4.87％ Methyl formate 5.98％ Methanol 17.00％ Ethanol 4.94％ Dimethyl carbonate 1.01％ Methyl glycolate 1.02％ Dimethyl oxalate 0.33％ 1.2-Propanediol 2.00％ Ethylene glycol 55.91％ 1.2-Butanediol 1.99％ 1.2-Hexanediol 0.96％ 1.4-Butanediol 0.983％ Ethylene carbonate 2.02％ Triethylene glycol 0.987％

[0091] S2. Constructing a standard curve model

[0092] S2.1. The 14 reference solution solutions are sequentially subjected to gas chromatography to obtain 14 reference solution chromatograms, and the elution time of the chromatographic peak on each reference solution chromatogram is collected to obtain the elution time corresponding to the 14 components.

[0093] In this embodiment, the setting conditions of gas chromatography are: the chromatographic column is DB-WAX, the size is 60m×320μm×0.25μm; the temperature program is as follows: Gradient 1: the heating rate is 10℃ / min, the temperature is 60℃, the temperature holding time and the running time do not need to be set, and the default is 0; Gradient 2: the heating rate is 20℃ / min, the temperature is 240℃, the temperature holding time is 8min, and the running time is 19min. The air flow rate is 400ml / min, the nitrogen gas flow rate is 40ml / min, and the tail gas flow rate (N 2 ) is 15ml / min, the flame is 14.4pA, the post-run flow rate is 1.15ml / min, the control mode is: flow rate is 3ml / min, pressure is 12.8psi, average linear velocity is 47.153cm / sec, and holding time is 1.0604min.

[0094] After the above detection parameters were set, 14 reference solutions were respectively subjected to gas chromatography detection to obtain the peak times corresponding to the 14 components, see Table 2.

[0095] S2.2, the above standard mixed alcohol solution is subjected to gas chromatography to obtain a standard mixed chromatogram (see Figure 1 ), and at the same time, the various chromatographic peaks on the standard mixed chromatogram are qualitatively characterized according to the peak elution time in step S2.1 to confirm the components corresponding to the various chromatographic peaks on the standard mixed chromatogram.

[0096] S2.3. Then, each chromatographic peak on the standard mixed chromatogram is quantitatively analyzed to obtain the peak area of ​​each chromatographic peak, that is, to obtain the peak area corresponding to each component. For details, see Table 2.

[0097] Table 2 Peak areas corresponding to the 14 components

[0098]

[0099] S2.4. Change the content of each component in the standard mixed alcohol solution, and according to the method of step S2.2 and step S2.3, obtain the corresponding peak area of ​​each component at different known contents.

[0100] In this embodiment, the content of each component in the standard mixed alcohol solution is changed twice to obtain the corresponding peak area at different contents. In this embodiment, the content refers to the mass fraction.

[0101] Preferably, the content of each component is shown in Table 3, and a reference solution and a standard mixed alcohol solution are prepared respectively. According to step S2.1, the retention time corresponding to each component is obtained (see Table 3), and the chromatogram corresponding to the standard mixed alcohol solution is obtained by continuing to refer to the method of steps S2.2 and S2.3 (see Figure 2 ), through quantitative and qualitative analysis, the corresponding peak area of ​​each component at different known contents was obtained (see Table 3).

[0102] Table 3 Retention time and peak area corresponding to different contents of components

[0103]

[0104] Preferably, the content of each component is shown in Table 3, and a reference solution and a standard mixed alcohol solution are prepared respectively. According to step S2.1, the retention time corresponding to each component is obtained (see Table 4), and the chromatogram corresponding to the standard mixed alcohol solution is obtained by continuing to refer to the method of steps S2.2 and S2.3 (see Figure 3 ), through quantitative and qualitative analysis, the corresponding peak area of ​​each component at different known contents was obtained (see Table 4).

[0105] Table 4 Retention time and peak area corresponding to different contents of components

[0106]

[0107] S2.5. For each component, use the known content as the horizontal axis and the peak area as the vertical axis to draw a curve and perform normalization to construct a standard curve model corresponding to each component.

[0108] Based on the data of the 14 components in Tables 1, 2, 3 and 4, each component has three different contents and the peak area corresponding to each content. According to the above requirements, the curves are drawn and normalized to obtain the standard curve models corresponding to the components. A total of 14 standard curve models, i.e., standard curve equations, are obtained.

[0109] In this embodiment, the equation of the standard curve model is: Y=aX+b.

[0110] Where: Y is the peak area, X is the content of the component, a is the slope, and b is the intercept. a and b are all constants.

[0111] In this embodiment, three groups of contents of 14 components are designed, and 14 standard curve models are finally determined. Each standard curve model contains three groups of coordinate data; when more groups of content design are used, the accuracy of the obtained standard curve model is higher.

[0112] S3. Actual sample testing

[0113] S3.1. Collect byproducts of ethylene glycol production, i.e. mixed alcohol samples, in real time. The sampling method is the conventional sampling method.

[0114] S3.2. Filter the mixed alcohol sample using a water filter membrane, specifically a circular filter with a pore size of 0.45 μm, to remove impurities in the sample.

[0115] For the sample collected, it is also necessary to determine whether the collected mixed alcohol sample contains crystal particles, because the sample containing crystal particles will block the gas chromatograph, so the chromatographic analysis cannot be performed directly. If it contains crystal particles, an organic reagent needs to be added to dissolve the crystal particles. Preferably, the organic reagent is acetonitrile.

[0116] S3.3. Referring to the method of step 2.2 and step S2.3, obtain the peak area corresponding to the component to be analyzed in the mixed alcohol sample, and then substitute it into the respective standard curve models to obtain the content of the component to be analyzed in the mixed alcohol sample.

[0117] In this embodiment, a total of 24 mixed alcohol samples were sampled, and a corresponding chromatogram was first obtained for each mixed alcohol sample. Then, qualitative and quantitative analysis was performed with reference to step S2.2 and step S2.3, respectively, to obtain the peak areas of the components contained, and further substituted into the respective standard curve equations to obtain the content of the components to be analyzed, i.e., the mass fraction, see Table 5. The water content in each mixed alcohol sample was measured using a moisture detector, see Table 5.

[0118] Table 5 Contents of the components to be analyzed in 24 mixed alcohol samples

[0119]

[0120]

[0121] As can be seen from the structure of Table 5, the analytical method of the present invention can determine the contents of various components in the ethylene glycol byproduct mixed alcohol, and the detection method is fast, has small differences, and has high consistency. It can provide a reference for the sales and post-processing of the ethylene glycol byproduct mixed alcohol and increase economic benefits.

[0122] Furthermore, the content of each component in the mixed alcohol sample No. 1 was analyzed by using a distillation method. The distillation method referred to the existing distillation method for determining the ethanol content. After the measurement, it was found that the alcohol content was 70.52%.

[0123] It can be seen from the measurement data of the distillation method that the components in the existing distillation analysis results are unclear, and the content of all components is represented only by the alcohol content. However, the analysis method provided by the present invention separates different components, and the analysis results have higher reliability and accuracy.

[0124] Obviously, the above-described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

Claims

1. A method for analyzing mixed alcohols produced as a byproduct of ethylene glycol, characterized in that: The following steps are involved: S1. Solution preparation According to the components to be analyzed in the ethylene glycol byproduct mixed alcohol, prepare corresponding reference solution and standard mixed alcohol solution; There are multiple components to be analyzed, and there are multiple reference solutions, which are prepared from the corresponding components to be analyzed; the standard mixed alcohol solution refers to a mixed solution containing multiple components to be analyzed at the same time, and the content of each component to be analyzed in the standard mixed alcohol solution is known; S2. Constructing a standard curve model S2.

1. For the above-mentioned multiple reference solution, sequentially perform gas chromatography to obtain multiple reference solution chromatograms, respectively, and collect the elution time of the chromatographic peak on each reference solution chromatogram, that is, obtain the elution time corresponding to each component; S2.2, obtaining a standard mixed chromatogram of the standard mixed alcohol solution by gas chromatography, and qualitatively analyzing each chromatographic peak on the standard mixed chromatogram according to the peak elution time in step S2.1 to confirm the components corresponding to each chromatographic peak on the standard mixed chromatogram; S2.3, then quantitatively analyze each chromatographic peak on the standard mixed chromatogram to obtain the peak area of ​​each chromatographic peak, that is, obtain the peak area corresponding to each component; S2.4, changing the content of each component to prepare a reference solution and a standard mixed alcohol solution respectively, and according to the method of step S2.1 to step S2.3, obtaining the corresponding peak area of ​​each component at different known contents; S2.

5. For each component, use the known content as the horizontal axis and the peak area as the vertical axis to draw a curve and perform normalization to construct a standard curve model corresponding to each component; S3. Actual sample testing S3.

1. Real-time collection of by-products in ethylene glycol production, i.e. mixed alcohol samples; S3.2, filtering the mixed alcohol sample; S3.

3. Referring to the method of step 2.2 and step S2.3, obtain the peak area corresponding to the component to be analyzed in the mixed alcohol sample, and then substitute it into the respective standard curve models to obtain the content of the component to be analyzed in the mixed alcohol sample.

2. The method for analyzing the ethylene glycol byproduct mixed alcohol according to claim 1, characterized in that: In step S1, the components to be analyzed are methylal, methanol, dimethyl carbonate, dimethyl oxalate, ethylene glycol, 1.2-hexanediol, ethylene carbonate, methyl formate, ethanol, methyl glycolate, 1.2-propylene glycol, 1.2-butylene glycol, 1.4-butylene glycol and triethylene glycol.

3. The method for analyzing the ethylene glycol byproduct mixed alcohol according to claim 1, characterized in that: In step S2, the conditions of gas chromatography are: The chromatographic column was DB-WAX with dimensions of 60 m × 320 μm × 0.25 μm; The temperature program is as follows: Gradient 1: heating rate is not more than 10°C / min, temperature setting is not higher than 100°C; Gradient 2: heating rate is not more than 20°C / min, temperature setting is not higher than 240°C, and temperature holding time is not less than 8 minutes.

4. The method for analyzing the ethylene glycol byproduct mixed alcohol according to claim 1, characterized in that: In step S3, filtration is performed using a water filter membrane.

5. The method for analyzing the ethylene glycol byproduct mixed alcohol according to claim 4, characterized in that: The water filter membrane has a pore size of 0.45 μm.

6. The method for analyzing ethylene glycol byproduct mixed alcohol according to claim 1, characterized in that: In step S3, it is also necessary to determine whether the collected mixed alcohol sample contains crystal particles. If it contains crystal particles, an organic reagent needs to be added to dissolve the crystal particles.

7. The method for analyzing the ethylene glycol byproduct mixed alcohol according to claim 6, characterized in that: The organic reagent is acetonitrile.

8. An analysis system for implementing the analysis method of ethylene glycol byproduct mixed alcohol according to claim 1, characterized in that: The analysis system includes a liquid preparation unit, a gas chromatography analysis unit, a sample collection unit and a pretreatment unit; The pretreatment unit is used to filter the collected mixed alcohol sample; The liquid preparation unit is used to prepare each reference substance solution and each standard mixed alcohol solution; The gas chromatography analysis unit is used to detect and obtain the chromatograms corresponding to each reference solution, each standard mixed alcohol solution and the mixed alcohol sample, and to perform qualitative and quantitative analysis on each chromatogram to obtain the peak area of ​​each reference solution; The model building unit is used to build a standard curve model corresponding to each reference substance according to the known content and the peak area of ​​each reference substance; The sample collection unit is used to collect mixed alcohol samples from ethylene glycol production.

9. The analysis system according to claim 7, characterized in that The pretreatment unit is a filter screen, the filter screen is circular, and the mesh diameter of the filter screen is 0.45 μm.

Images