Method for measuring oxidation efficiency of oxidation liquid in hydrogen peroxide production process

Abstract

The invention relates to the field of rapid detection, and discloses a method for determining the oxidation efficiency of an oxidation solution in a hydrogen peroxide production process. The method comprises the following steps: (1) obtaining a plurality of standard oxidation liquids, a near infrared spectrum and a characteristic spectrum wave band; (2) performing first three-dimensional transformation on the characteristic spectral band to obtain a first three-dimensional spectrogram and a first correction model; optionally, the method further comprises the following steps: carrying out additional three-dimensional transformation on the characteristic spectral band to obtain an additional three-dimensional spectrogram, and obtaining an additional correction model; fusing the obtained correction models to obtain a fusion model; and (3) taking a to-be-detected oxidation liquid, collecting a near infrared spectrum, obtaining a corresponding characteristic spectrum wave band, obtaining a three-dimensional spectrogram according to the step (2), and substituting the three-dimensional spectrogram into the first correction model or the fusion model to obtain the oxidation efficiency. The method can quickly, accurately and simply obtain the oxidation efficiency of the oxidation liquid.

Description

Technical Field

[0001] The invention relates to the field of rapid detection, and in particular to a method for determining the oxidation efficiency of an oxidizing liquid in a hydrogen peroxide production process. Background Art

[0002] The preparation method of hydrogen peroxide mainly adopts the anthraquinone method, which has a high degree of automation control, low product cost and energy consumption, and is suitable for large-scale production. However, since the raw materials, intermediate products and final products are almost all flammable and explosive or combustion-supporting substances, the production process is also relatively complicated. Therefore, it is particularly important to accurately and timely monitor the quality indicators of the hydrogen peroxide production process and make real-time adjustments.

[0003] Oxidation liquid is a liquid product formed after the oxidation reaction in the production process of hydrogen peroxide. Its main component is hydrogen peroxide, and it also contains a small amount of unreacted anthraquinone, decomposition products of hydrogen peroxide, catalyst and other impurities. Oxidation efficiency is a relatively important parameter in the production process of hydrogen peroxide by anthraquinone method, which can reflect the output and quality of hydrogen peroxide.

[0004] However, in the current hydrogen peroxide production process, the oxidation efficiency is mainly analyzed manually. The method for determining the oxidation efficiency is generally: take part of the sample, add potassium permanganate titration solution, and calculate the corresponding oxidation efficiency (that is, the actual hydrogen peroxide content in the sample) according to the content of the titration solution consumed at the titration endpoint, in g / L. Since manual analysis is cumbersome and time-consuming, it is difficult to give a more accurate result in a short time; on the other hand, in manual analysis, the requirements for operators are high, and the labor intensity of operators is large, they are in contact with the working solution for a long time, the operating environment is poor, and the reagents used also have the defect of polluting the environment. Therefore, the current manual analysis does not have an advantage in the industrial production of hydrogen peroxide.

[0005] Therefore, it is necessary to develop a method that can accurately, quickly and simply measure the oxidation efficiency of the oxidizing solution. Summary of the invention

[0006] The purpose of the present invention is to overcome the above-mentioned problems existing in the prior art and to provide a method for determining the oxidation efficiency of an oxidizing liquid in a hydrogen peroxide production process, which method can quickly, accurately and simply obtain the oxidation efficiency of the oxidizing liquid.

[0007] In order to achieve the above object, the present invention provides a method for determining the oxidation efficiency of an oxidizing liquid in a hydrogen peroxide production process, the method comprising:

[0008] (1) obtaining a plurality of standard oxidizing solutions, wherein the plurality of standard oxidizing solutions have known and different oxidation efficiencies, and obtaining near-infrared spectra and characteristic spectral bands of the standard oxidizing solutions respectively;

[0009] (2) performing a first three-dimensional transformation on the characteristic spectral band to obtain a first three-dimensional spectrum, and performing regression analysis on the first three-dimensional spectrum and the oxidation efficiency of the standard oxidation solution to obtain a first calibration model;

[0010] Optionally, the method further comprises performing another three-dimensional transformation on the characteristic spectral band to obtain another three-dimensional spectrum, performing regression analysis on the other three-dimensional spectrum and the oxidation efficiency of the standard oxidation solution to obtain another correction model; fusing the obtained two or more correction models to obtain a fusion model;

[0011] (3) Taking an oxidizing liquid with unknown oxidation efficiency as the oxidizing liquid to be tested, collecting a near-infrared spectrum and obtaining a corresponding characteristic spectral band, and according to step (2), obtaining a three-dimensional spectrum, and substituting the three-dimensional spectrum into the first calibration model or fusion model obtained in step (2) to obtain the oxidation efficiency of the oxidizing liquid to be tested.

[0012] Through the above technical solution, after the spectrum is transformed into three dimensions, more comprehensive information can be obtained, and the influence of overlapping peaks can be avoided, so that the accuracy of the result is higher. In a preferred case, another three-dimensional transformation is performed and a fusion model is obtained, which can further improve the accuracy of the model and further ensure the accuracy and stability of the result. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 It is a correlation diagram of the measured values ​​and calculated values ​​of the verification set in Example 1. DETAILED DESCRIPTION

[0014] The endpoints and any values ​​of the ranges disclosed in this article are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this article.

[0015] The present invention provides a method for determining the oxidation efficiency of an oxidizing liquid in a hydrogen peroxide production process, the method comprising:

[0016] (1) obtaining a plurality of standard oxidizing solutions, wherein the plurality of standard oxidizing solutions have known and different oxidation efficiencies, and obtaining near-infrared spectra and characteristic spectral bands of the standard oxidizing solutions respectively;

[0017] (2) performing a first three-dimensional transformation on the characteristic spectral band to obtain a first three-dimensional spectrum, and performing regression analysis on the first three-dimensional spectrum and the oxidation efficiency of the standard oxidation solution to obtain a first calibration model;

[0018] Optionally, the method further comprises performing another three-dimensional transformation on the characteristic spectral band to obtain another three-dimensional spectrum, and performing regression analysis on the other three-dimensional spectrum and the oxidation efficiency of the standard oxidation solution to obtain another calibration model;

[0019] fusing the obtained two or more correction models to obtain a fusion model;

[0020] (3) Taking an oxidizing liquid with unknown oxidation efficiency as the oxidizing liquid to be tested, collecting a near-infrared spectrum and obtaining a corresponding characteristic spectral band, and according to step (2), obtaining a three-dimensional spectrum, and substituting the three-dimensional spectrum into the first calibration model or fusion model obtained in step (2) to obtain the oxidation efficiency of the oxidizing liquid to be tested.

[0021] Generally, in the three-dimensional processing of the spectrum, the three dimensions of the obtained three-dimensional spectrum are wave number (which can be the X-axis and can range from 1000-10000cm -1 ), absorbance (which can be the Y axis, the range can be 0-100%) and band type (which can be the Z axis). Compared with other materials, the method of the present invention can obtain more accurate results for the oxidizing liquid in the production process of hydrogen peroxide.

[0022] The inventors of the present invention have found that for the oxidizing liquid in the hydrogen peroxide production process, performing three-dimensional transformation in the above manner can effectively avoid the influence of overlapping peaks and obtain more comprehensive information. The first calibration model or fusion model constructed in this way is more accurate. Substituting the three-dimensional spectrum of the oxidizing liquid with unknown oxidation efficiency into the first calibration model or fusion model, the result obtained is more accurate. In particular, when another three-dimensional transformation is used, the fusion model constructed together is more accurate and the result is more accurate.

[0023] Hydrogen peroxide is mainly produced by the anthraquinone method. The main reaction liquids involved in the production process generally include hydrogenation liquid, oxidation liquid and raffinate. The main process of the anthraquinone method includes: preparing anthraquinone (generally 2-ethyl anthraquinone) and an organic solvent (such as a mixed solvent of C9-C10 heavy aromatics, trioctyl phosphate and tetrabutyl urea) into a working solution, and controlling the total effective anthraquinone content to about 160g / L. Hydrogenation stage: under the conditions of 0.3MPa or above, 40-80°C and a catalyst (such as Pd catalyst), the anthraquinone in the working solution is hydrogenated and reduced by H2 to obtain anthrahydroquinone or tetrahydroanthrahydroquinone; in the oxidation stage, the material after the hydrogenation stage is subjected to an oxidation reaction with O2 at 30-60°C and slight compression to oxidize anthrahydroquinone and tetrahydroanthrahydroquinone to generate H2O2 and anthraquinone; then the material after the oxidation stage is subjected to extraction (the raffinate is the solution remaining after the H2O2 is extracted), regeneration, refining and concentration to obtain a 20wt%-50wt% H2O2 aqueous solution.

[0024] After obtaining the standard oxidation solution, the method for obtaining the oxidation efficiency therein is not particularly limited, and the oxidation efficiency therein can be obtained by the potassium permanganate titration method commonly used in the art.

[0025] According to the present invention, preferably, the fusion method includes: substituting the three-dimensional spectrograms obtained by each three-dimensional transformation into the corresponding correction models respectively, and obtaining the prediction values ​​of each correction model respectively;

[0026] Assign weights to each predicted value obtained, and adjust the weight values ​​so that the sum of the products of each weight value and the corresponding predicted value is close to the actual oxidation efficiency, wherein each weight value satisfies that each weight value is greater than 0 and less than 1, and the sum of each weight value is 1;

[0027] The fusion model is the sum of the products of each weight value and the corresponding correction model.

[0028] Such integration can further reduce errors and further ensure the accuracy of the results. It can be understood that the real oxidation efficiency refers to the oxidation efficiency obtained by the currently available manual titration method after obtaining the standard solution. In the process of adjusting the weight value, there can be many combinations that can be used. The sum of the products of each weight value and the corresponding predicted value in these combinations can be taken to be closer to the value of the real oxidation efficiency.

[0029] When collecting samples, it is generally sufficient to make the samples uniformly distributed within a possible range, and the present invention has no particular limitation. However, preferably, in step (1), the oxidation efficiency of the standard oxidation solution is 0.5-7 g / L, preferably 0.8-6.5 g / L (for example, it can be 0.8 g / L, 0.9 g / L, 1 g / L, 1.5 g / L, 2 g / L, 2.5 g / L, 3 g / L, 3.5 g / L, 4 g / L, 4.5 g / L, 5 g / L, 5.5 g / L, 6 g / L, 6.5 g / L, and the range formed by any two of the above values ​​and the value within the range).

[0030] According to the present invention, preferably, in step (1), the number of the standard oxidizing solutions is not less than 28, and more preferably is 40-220 (for example, it can be 40, 50, 80, 100, 120, 150, 180, 200, 220, and a range formed by any two of the above values, and a value within the range).

[0031] According to the present invention, preferably, the conditions for obtaining near-infrared spectra include: the collection temperature is 15-55°C, preferably 20-28°C (for example, it can be 20°C, 22°C, 25°C, 28°C); the wave number range is 3000-11000cm -1 ; The acquisition resolution is 2-16cm -1 , preferably 5-12cm-1 (For example, it can be 5cm -1 、6cm -1 、7cm -1 、8cm -1 、9cm -1 , 10cm -1 、11cm -1 、12cm -1 ).

[0032] When collecting near infrared spectra, the sample is injected into about two-thirds of the volume of the cuvette, and the cuvette containing the sample is sealed, and the sealed cuvette can be placed in a temperature-controlled sample cell rack for spectrum collection. The optical path of the cuvette can be 1-5 mm. The instrument when collecting near infrared spectra is not particularly limited and can be a conventional choice in the art, for example, Antaris II near infrared spectrometer (Thermo Fisher Company) can be used.

[0033] According to the present invention, preferably, the wave number interval of the characteristic spectral band is 3880-4204cm -1 and 4458-6194cm -1 The inventors of the present invention further discovered that the selection of the above-mentioned wavelength bands can further fully extract information from the spectrum.

[0034] It can be understood that after the characteristic spectral band is obtained, that is, the spectrum including the characteristic spectral band is obtained, and the characteristic spectral band is transformed three-dimensionally, that is, the spectrum including the characteristic spectral band is transformed three-dimensionally.

[0035] According to the present invention, preferably, the three-dimensional transformation method includes: performing first-order differentiation, segmentation, interpolation and stacking of characteristic spectral bands in sequence. According to the present invention, preferably, the three-dimensional transformation method includes: performing second-order differentiation, segmentation, interpolation and stacking of characteristic spectral bands in sequence.

[0036] According to the present invention, preferably, the number of segments is 2-5 (for example, it can be 2, 3, 4, or 5). After segmentation, the band type dimension of the corresponding three-dimensional spectrum corresponds to the number of segments (i.e., one segment is one band type).

[0037] According to the present invention, preferably, the window width of the first-order differential is 6-15 (for example, it can be 6, 7, 8, 9, 10, 11, 12, 13, 14, 15).

[0038] According to the present invention, preferably, the window width of the second-order differential is 18-25 (for example, it can be 18, 19, 20, 21, 22, 23, 24, 25).

[0039] It can be understood that when the fusion model is substituted, since the fusion model is obtained through the correction model, and the correction model is directly related to the three-dimensional spectrum, the three-dimensional spectrum is substituted into the fusion model through the correction model.

[0040] The inventors of the present invention further discovered in their research that the use of the first-order differential and the second-order differential as described above can further ensure the elimination of the influence of interference factors and improve the accuracy of the model.

[0041] When the above three-dimensional transformation method is adopted, the accuracy of the obtained model can be further ensured.

[0042] The present invention has no particular limitation on the method of regression analysis, but preferably, the regression analysis method is multidimensional partial least squares analysis, which can further ensure the accuracy of the model.

[0043] The inventors of the present invention further found in the study that for the oxidizing liquid in the process of preparing hydrogen peroxide by the anthraquinone method, by selecting the specific characteristic spectral band defined by the present invention, and coordinating the spectral processing methods of the first-order differential, second-order differential, segmentation, interpolation and stacking array as described above, especially coordinating the multidimensional partial least squares analysis applicable to the three-dimensional spectrum, and fusing the obtained correction models in the manner defined by the present invention, the obtained fusion model has a higher accuracy. Compared with the use of other spectra, or other processing methods for the spectrum, or not performing a three-dimensional transformation on the spectrum and using a method (such as partial least squares analysis) applicable to constructing a correction model corresponding to a two-dimensional spectrum, the near-infrared spectrum defined by the present invention, and the processing method of the present invention, the obtained fusion model has a higher accuracy and a higher accuracy of the calculation result. The specific method provided by the present invention is particularly suitable for determining the oxidation efficiency of the oxidizing liquid in the hydrogen peroxide production process.

[0044] The present invention will be described in detail below through examples.

[0045] In the following examples, the oxidizing liquid is obtained during the process of preparing hydrogen peroxide by the anthraquinone process.

[0046] In step (I) of the following examples, the oxidation efficiency in the standard oxidation solution is determined by potassium permanganate titration, and the oxidation efficiency value obtained by potassium permanganate titration is recorded as the measured value.

[0047] The instrument used to collect near-infrared spectra was Antaris II near-infrared spectrometer (Thermo Fisher).

[0048] The operations after spectrum acquisition were performed in MATLAB.

[0049] Example 1

[0050] Method for describing the present invention for determining the oxidation efficiency of the oxidizing liquid in the hydrogen peroxide production process

[0051] (1) 45 oxidation solutions were obtained as standard oxidation solutions, and the oxidation efficiencies thereof were measured (the oxidation efficiencies were distributed in the range of 0.91-6.08 g / L, and the difference between every two adjacent oxidation efficiencies was in the range of 0.1-0.5 g / L).

[0052] The sample is injected into the cuvette until it is about two-thirds of the cuvette volume, and the cuvette containing the sample is sealed. The sealed cuvette is placed in a temperature-controlled sample cell rack for spectrum collection. The optical path of the cuvette is 2 mm. The conditions for collecting near-infrared spectra include: temperature of 25°C, and the collected wavenumber range of 3500-10000 cm -1 , resolution 8cm -1 , scanned 128 times.

[0053] For the obtained near-infrared spectrum, the characteristic spectral band 3880-4204cm was selected -1 and 4458-6194cm -1 .

[0054] (2) For the characteristic spectral band, a first-order differential with a window width of 11 is performed, and then the band is divided into three segments (the wave number ranges of the three segments are 3880-4204cm -1 、4458-5230cm -1 、5234-6194cm -1 ), and interpolate and stack the arrays to obtain a three-dimensional spectrum X1;

[0055] For the characteristic spectral band, the second-order differential with a window width of 21 is performed, and then the band is divided into three sections (the wave number ranges of the three sections are 3880-4204cm -1 、4458-5230cm -1 、5234-6194cm -1 ), and interpolate and stack the arrays to obtain a three-dimensional spectrum X2;

[0056] Through multidimensional partial least squares analysis, the three-dimensional spectrum X1 and the oxidation efficiency of the standard oxidation solution were regressed to obtain the correction model M1;

[0057] Through multidimensional partial least squares analysis, the three-dimensional spectrum X2 and the oxidation efficiency of the standard oxidation solution were regressed to obtain the correction model M2;

[0058] Substitute the three-dimensional spectrum X1 into the calibration model M1 to obtain the predicted value R1 of the calibration model M1;

[0059] Substitute the three-dimensional spectrum X2 into the calibration model M2 to obtain the predicted value R2 of the calibration model M2;

[0060] Assign weights a and b to R1 and R2 respectively. According to aR1+bR2, a and b are adjusted until the calculation result of aR1+bR2 is close to the actual oxidation efficiency of the oxidizing liquid, and a is 0.485 and b is 0.515.

[0061] Then we get the fusion model M=aM1+bM2.

[0062] (3) Fifteen oxidation solutions from the anthraquinone process for producing hydrogen peroxide with unknown oxidation efficiency were selected as the validation set and processed as follows:

[0063] The method in step (1) is adopted to first determine the oxidation efficiency by potassium permanganate titration method, collect a near-infrared spectrum, select a characteristic spectrum band, and process the characteristic spectrum band in step (2) to obtain a three-dimensional spectrum X1' and a three-dimensional spectrum X2' respectively.

[0064] Substitute X1' and X2' into the fusion model of step (2) to obtain the oxidation efficiency (calculated value).

[0065] The measured and calculated values ​​of the 15 samples in the validation set, as well as the deviation between the two (measured value minus calculated value) are shown in Table 1. In addition, the root mean square error of prediction (RMSEP) and R (correlation coefficient) are used to evaluate the performance of the fusion model, where

[0066]

[0067] Where n is the total number of samples in the validation set, yi is the measured value of the i-th sample, is the calculated value of the ith sample.

[0068]

[0069] Among them, n is the total number of samples in the validation set, y i is the measured value of the i-th sample, y i ^ is the calculated value of the i-th sample, y — is the average value of the actual values ​​of the validation set samples. By calculation, we can get R = 0.949.

[0070] Table 1

[0071]

[0072] In addition, a correlation diagram is drawn with the measured values ​​(x-axis) and calculated values ​​(y-axis) of the 15 samples in the validation set, see Figure 1 (where R is the correlation coefficient).

[0073] It can be seen that the method provided by the present invention can quickly, simply and accurately determine the oxidation efficiency of the oxidizing liquid in the hydrogen peroxide production process, and the prediction results at various concentrations are relatively accurate and have high stability.

[0074] Comparative Example 1

[0075] The characteristic spectral band is obtained in the manner of step (1) of Example 1, and the characteristic spectral band is subjected to a second-order differential with a window width of 21, and then the band after the second-order differential and the oxidation efficiency of the standard oxidation solution are subjected to partial least squares analysis to obtain the model M D .

[0076] Then, 15 oxidation solutions of hydrogen peroxide produced by the anthraquinone process with unknown oxidation efficiency were taken as the validation set, and the procedure of step (3) of Example 1 was followed to "select characteristic spectral bands", and then the obtained characteristic spectral bands were subjected to second-order differentiation with a window width of 21, and then the bands after the second-order differentiation were substituted into the model M. D In the above example, we get the model M D The results are shown in Table 2.

[0077] Calculate according to the model M in the manner of Example 1 D The prediction root mean square error of the obtained results is shown in Table 2.

[0078] Table 2

[0079]

[0080] RMSEP can characterize the accuracy of the method. The smaller the RMSEP, the more accurate the result. It can be seen that the method provided by the present invention has a smaller deviation from the actual measured value of the standard method, and the RMSEP is also smaller. The method provided by the present invention has better accuracy.

[0081] The preferred embodiments of the present invention are described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be regarded as the contents disclosed by the present invention and belong to the protection scope of the present invention.

Claims

1. A method for determining the oxidation efficiency of an oxidizing liquid in a hydrogen peroxide production process, characterized in that: The method includes: (1) obtaining a plurality of standard oxidizing solutions, wherein the plurality of standard oxidizing solutions have known and different oxidation efficiencies, and obtaining near-infrared spectra and characteristic spectral bands of the standard oxidizing solutions respectively; (2) performing a first three-dimensional transformation on the characteristic spectral band to obtain a first three-dimensional spectrum, and performing regression analysis on the first three-dimensional spectrum and the oxidation efficiency of the standard oxidation solution to obtain a first calibration model; Optionally, the method further comprises performing another three-dimensional transformation on the characteristic spectral band to obtain another three-dimensional spectrum, and performing regression analysis on the other three-dimensional spectrum and the oxidation efficiency of the standard oxidation solution to obtain another calibration model; fusing the obtained two or more correction models to obtain a fusion model; (3) Taking an oxidizing liquid with unknown oxidation efficiency as the oxidizing liquid to be tested, collecting a near-infrared spectrum and obtaining a corresponding characteristic spectral band, and obtaining a three-dimensional spectrum according to step (2), and substituting the three-dimensional spectrum into the first calibration model or fusion model obtained in step (2) to obtain the oxidation efficiency of the oxidizing liquid to be tested.

2. The method according to claim 1, wherein: The fusion method includes: substituting the three-dimensional spectra obtained by each three-dimensional transformation into the corresponding correction models respectively, and obtaining the prediction values ​​of each correction model respectively; Assign weights to each predicted value obtained, and adjust the weight values ​​so that the sum of the products of each weight value and the corresponding predicted value is close to the actual oxidation efficiency, wherein each weight value satisfies that each weight value is greater than 0 and less than 1, and the sum of each weight value is 1; The fusion model is the sum of the products of each weight value and the corresponding correction model.

3. The method according to claim 1, wherein: In step (1), the oxidation efficiency of the standard oxidation solution is 0.5-7 g / L, preferably 0.8-6.5 g / L.

4. The method according to claim 1 or 3, wherein: In step (1), the number of the standard oxidizing solutions is not less than 28, preferably 40-220.

5. The method according to claim 1 or 2, wherein: The conditions for obtaining near-infrared spectra include: acquisition temperature of 15-55°C, preferably 20-28°C; wave number range of 3000-11000cm -1 ; The acquisition resolution is 2-16cm -1 , preferably 5-12cm -1 .

6. The method according to claim 1 or 2, wherein: The wave number range of the characteristic spectral band is 3880-4204cm -1 and 4458-6194cm -1 .

7. The method according to claim 1, wherein: The three-dimensional transformation method includes: performing first-order differentiation, segmentation, interpolation and stacking on the characteristic spectral bands in sequence.

8. The method according to claim 1, wherein: The three-dimensional transformation method includes: performing second-order differentiation, segmentation, interpolation and stacking on the characteristic spectral bands in sequence.

9. The method according to claim 7 or 8, wherein: The number of segments is 2-5; And / or, the window width of the first-order differential is 6-15; And / or, the window width of the second-order differential is 18-25.

10. The method according to claim 1 or 2, wherein: The regression analysis method is multidimensional partial least squares analysis.

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