Method capable of simultaneously determining hydrogenation efficiency of hydrogenation liquid and oxidation efficiency of oxidation liquid in hydrogen peroxide production

Abstract

The invention relates to the field of spectrum detection, and discloses a method for simultaneously determining the hydrogenation efficiency of a hydrogenation solution and the oxidation efficiency of an oxidation solution in hydrogen peroxide production. The method comprises the following steps: (1) obtaining a standard hydrogenation solution and a standard oxidation solution; collecting a near infrared spectrogram; (2) selecting a characteristic spectrum wave band; (3) constructing a prediction model by adopting a random forest algorithm and taking the characteristic spectral band as an input variable and the hydrogenation efficiency and the oxidation efficiency as output variables; and (4) obtaining a reaction solution to be detected and a corresponding characteristic spectrum wave band, and substituting the reaction solution and the corresponding characteristic spectrum wave band into the prediction model to obtain hydrogenation efficiency or oxidation efficiency. The method is suitable for measuring the hydrogenation efficiency of the hydrogenation liquid and the oxidation efficiency of the oxidation liquid at the same time, the result can be rapidly, simply and accurately obtained, and compared with the prior art, the method provided by the invention has the obvious advantages of operation, accuracy and repeatability.

Description

Technical Field

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

[0002] The anthraquinone method, primarily used to prepare hydrogen peroxide, offers a high degree of automation, low production costs and energy consumption, making it suitable for large-scale production. However, since the raw materials, intermediates, and final products are almost always flammable, explosive, or combustion-supporting, the production process is complex. Therefore, accurate and timely monitoring of quality indicators and real-time adjustments during the hydrogen peroxide production process are crucial.

[0003] Among them, the hydrogenation liquid hydrogen effect (hydrogenation efficiency) and the oxidation liquid oxygen effect (oxidation efficiency) are two important analytical items in the anthraquinone method hydrogen peroxide production process, which directly affect the output, quality and production safety of hydrogen peroxide. The analysis frequency is very high, generally once every 4-8 hours.

[0004] Hydrogenated liquid is the liquid product formed after the hydrogenation stage of the hydrogen peroxide production process. Its primary component is anthrahydroquinone, along with small amounts of unreacted anthraquinone and other impurities such as catalyst. The general method for measuring hydrogen efficiency is to take a sample of the hydrogenated liquid, introduce oxygen into it for oxidation (the hydrogenated liquid itself does not contain hydrogen peroxide, so oxygen must be added to oxidize it into hydrogen peroxide. The hydrogen efficiency is the amount of hydrogen peroxide produced after oxygenation, i.e., the potential content). Potassium permanganate titrant is then added until the hydrogen peroxide reaction is complete. The hydrogen efficiency (i.e., the potential hydrogen peroxide content) of the hydrogenated liquid is calculated based on the amount of titrant consumed at the titration endpoint, expressed in g / L.

[0005] Oxidation liquid is the liquid product formed after the oxidation reaction during the hydrogen peroxide production process. Its primary component is hydrogen peroxide, along with small amounts of unreacted anthraquinone, hydrogen peroxide decomposition products, and other impurities such as the catalyst. The oxygen efficiency is generally determined by taking a portion of the sample, adding potassium permanganate titrant, and calculating the corresponding oxygen efficiency (i.e., the actual hydrogen peroxide content in the sample) based on the amount of titrant consumed at the titration endpoint. The unit of measurement is g / L.

[0006] Manual analysis is cumbersome and time-consuming, making it difficult to provide relatively accurate results in a short period of time. On the other hand, manual analysis places high demands on operators, and operators are subject to high labor intensity, prolonged contact with the working fluid, poor operating environment, and the reagents used have the defect of polluting the environment. Therefore, current manual analysis does not have an advantage in the industrial production of hydrogen peroxide. In particular, in existing rapid analysis methods, hydrogen efficiency and oxygen efficiency are analyzed separately, that is, hydrogen efficiency is analyzed separately using the hydrogen efficiency analysis method, and oxygen efficiency is analyzed separately using the oxygen efficiency analysis method, that is, both are analyzed and measured according to their respective analysis methods. This makes the operation more cumbersome, places higher demands on operators, and manual operation is prone to errors, with the risk of low accuracy and poor repeatability.

[0007] Therefore, it is necessary to develop a method that can accurately, quickly, and simply measure the hydrogenation efficiency and oxidation efficiency. In particular, it is best to establish a unified and rapid analytical method that can simultaneously measure the hydrogenation efficiency of the hydrogenating solution and the oxidation efficiency of the oxidizing solution to further improve the analytical efficiency. Summary of the Invention

[0008] The object of the present invention is to overcome the above-mentioned problems existing in the prior art and provide a method for simultaneously determining the hydrogenation efficiency of the hydrogenating liquid and the oxidation efficiency of the oxidizing liquid in hydrogen peroxide production. The method is suitable for determining the hydrogenation efficiency of the hydrogenating liquid and the oxidation efficiency of the oxidizing liquid at the same time, and can obtain results quickly, simply and accurately. Compared with the prior art, the method provided by the present invention has obvious operational and accuracy advantages and good stability.

[0009] In order to achieve the above object, the present invention provides a method for simultaneously determining the hydrogenation efficiency of the hydrogenation liquid and the oxidation efficiency of the oxidation liquid in hydrogen peroxide production, the method comprising:

[0010] (1) obtaining a plurality of standard hydrogenation solutions with known and different hydrogenation efficiencies, and a plurality of standard oxidation solutions with known and different oxidation efficiencies; and collecting near-infrared spectra of the above standard solutions;

[0011] (2) Select the characteristic spectral band of the above near-infrared spectrum;

[0012] (3) using a random forest algorithm, taking the characteristic spectral band obtained in step (2) as an input variable and the corresponding hydrogenation efficiency and oxidation efficiency obtained in step (1) as output variables, and constructing a prediction model between the input variables and the output variables;

[0013] (4) Obtaining the reaction liquid to be tested, collecting a near-infrared spectrum and obtaining the corresponding characteristic spectral band, and substituting it into the prediction model to obtain the hydrogenation efficiency or oxidation efficiency of the reaction liquid to be tested.

[0014] Through the above technical solution, a prediction model suitable for measuring the hydrogenation efficiency of the hydrogenated liquid and the oxidation efficiency of the oxidizing liquid can be obtained. Therefore, when measuring the hydrogen efficiency or the oxygen efficiency, there is no need to process them separately for their respective objects. It is only necessary to substitute the corresponding characteristic spectral band into the prediction model. If the reaction liquid to be measured is the hydrogenated liquid, the result obtained is the hydrogen efficiency; if the reaction liquid to be measured is the oxidizing liquid, the result obtained is the oxygen efficiency. This is more convenient, fast, and simple, and the result has good accuracy and stability. Compared with the prior art, the method provided by the present invention can avoid complex manual processing processes, is more efficient, greatly improves the analysis and operation environment, and has obvious advantages. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 3 is a correlation diagram of the measured values ​​and the calculated values ​​obtained in Example 1 of the present invention. DETAILED DESCRIPTION

[0016] The endpoints of the ranges and any values ​​disclosed herein 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 endpoints of each range, the endpoints of each range and 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 to be specifically disclosed herein.

[0017] The present invention provides a method for simultaneously determining the hydrogenation efficiency of a hydrogenating liquid and the oxidation efficiency of an oxidizing liquid in hydrogen peroxide production, the method comprising:

[0018] (1) obtaining a plurality of standard hydrogenation solutions with known and different hydrogenation efficiencies, and a plurality of standard oxidation solutions with known and different oxidation efficiencies; and collecting near-infrared spectra of the above standard solutions;

[0019] (2) Select the characteristic spectral band of the above near-infrared spectrum;

[0020] (3) using a random forest algorithm, taking the characteristic spectral band obtained in step (2) as an input variable and the corresponding hydrogenation efficiency and oxidation efficiency obtained in step (1) as output variables, and constructing a prediction model between the input variables and the output variables;

[0021] (4) Obtaining the reaction liquid to be tested, collecting a near-infrared spectrum and obtaining the corresponding characteristic spectral band, and substituting it into the prediction model to obtain the hydrogenation efficiency or oxidation efficiency of the reaction liquid to be tested.

[0022] Hydrogen peroxide (Hydrogen peroxide) is primarily produced using the anthraquinone process. The main reaction solutions involved in the production process generally include a hydrogenation solution, an oxidation solution, and a raffinate. The anthraquinone process involves preparing anthraquinone (typically 2-ethylanthraquinone) with an organic solvent (such as a mixed solvent of C9-C10 heavy aromatic hydrocarbons, trioctyl phosphate, and tetrabutyl urea) to form a working solution. In the hydrogenation stage, under conditions of pressure of 0.3 MPa or above, a temperature of 40-80°C, and a catalyst (such as Pd), the anthraquinone in the working solution is hydrogenated and reduced with H2 to produce anthrahydroquinone or tetrahydroanthrahydroquinone. In the oxidation stage, the product after the hydrogenation stage is further oxidized with O2 at 30-60°C under slight compression to produce H2O2 and anthraquinone. The product after the oxidation stage is then subjected to extraction (the raffinate is the solution remaining after H2O2 extraction), regeneration, purification, and concentration to produce a 20-50 wt% H2O2 aqueous solution.

[0023] The inventors of the present invention have discovered in their research that, by processing the hydrogenated liquid and the oxidizing liquid in the anthraquinone process according to the above method, and in particular by establishing a correction model through a random forest algorithm of nonlinear calculation, a relatively accurate and unified prediction model capable of simultaneously predicting the hydrogen efficiency of the hydrogenated liquid and the oxygen efficiency of the oxidizing liquid can be established. When used to calculate unknown hydrogen efficiency and oxygen efficiency, the results can be obtained quickly, simply and conveniently, and high accuracy and good repeatability can be guaranteed.

[0024] According to the present invention, preferably, in step (1), the hydrogenation efficiency of the standard hydrogenation liquid and the oxidation efficiency of the standard oxidation liquid are each independently 5-16 g / L.

[0025] According to the present invention, preferably, in step (1), the hydrogenation efficiency of the standard hydrogenation liquid and the oxidation efficiency of the standard oxidation liquid are each independently 7-14 (for example, it can be 7, 8, 9, 10, 11, 12, 13, 14 and the range formed by any two of the above values ​​and the value within the range) g / L.

[0026] It is understood that when collecting samples, it is generally desirable to have the sample conditions evenly distributed within the possible range, so as to further ensure the accuracy of the model obtained from the samples. Therefore, the hydrogenation efficiency of the standard hydrogenation liquid and the oxidation efficiency of the standard oxidation liquid are also preferably evenly distributed within the above range. For example, the difference between each two adjacent hydrogenation efficiency values ​​(or each two adjacent oxidation efficiency values) is preferably between 0.01-0.8 g / L.

[0027] According to the present invention, preferably, in step (1), the total number of standard hydrogenation liquids and standard oxidation liquids is not less than 100, more preferably 150-350 (for example, it can be 150, 180, 200, 220, 240, 260, 280, 300, 320, 330, 340, 350 and the range formed by any two of the above values ​​and the values ​​within the range). It can be understood that in order to further ensure the accuracy of the obtained model, a slightly larger number of samples is generally required. The inventors of the present invention have found in their research that within the above range, a model with better accuracy can be obtained. In addition, in order to make the calculation results of the hydrogenation efficiency and the oxidation efficiency better, the number of each of the standard hydrogenation liquid and the standard oxidation liquid should be equivalent, for example, they can each account for half of the total (or about half, for example, the difference between the number of each of the two and half of the total should not exceed 5% of the total).

[0028] The present invention has no particular limitation on the specific method of obtaining the near-infrared spectrum, and the method can be carried out according to conventional methods in the art. However, preferably, in step (1), the conditions for obtaining the near-infrared spectrum include: a temperature of 12-62°C (for example, 12, 15, 20, 22, 24, 25, 26, 28, 30, 35, 40, 45, 50, 60, 62, and a range formed by any two of the above values, and a value within the range); a wave number range of 3500-12000 cm -1 ; Resolution is 2-16 (for example, it can be 2, 4, 6, 7, 8, 9, 10, 12, 14, 16, and the range formed by any two of the above values ​​and the value within the range) cm -1 .

[0029] More preferably, in step (1), the conditions for obtaining the near-infrared spectrum include: a temperature of 20-30 (for example, 20, 22, 24, 26, 28, 30, and a range formed by any two of the above values, and a value within the range) ° C; a resolution of 6-10 (for example, 6, 7, 8, 9, 10, and a range formed by any two of the above values, and a value within the range) cm -1 . Can scan 64-128 times.

[0030] When collecting near-infrared spectra, the sample can be injected into the cuvette to about two-thirds of its volume, and the cuvette containing the sample can be sealed with a sealing film. The sealed cuvette can be placed in a temperature-controlled sample cell holder for spectrum collection. The optical path of the cuvette can be 1-2 mm. The instrument used when collecting the near-infrared spectra is not particularly limited and can be a conventional choice in the art, for example, an Antaris II near-infrared spectrometer (Thermo Fisher Corporation) can be used.

[0031] According to the present invention, preferably, in step (2), the characteristic spectrum band is within the range of 4000-8000 cm -1 , more preferably 4556-7596cm -1 The inventors of the present invention have further discovered that the selection of the above characteristic spectral bands can further fully reflect information related to hydrogen efficiency and oxygen efficiency.

[0032] According to the present invention, preferably, before performing step (3), the method further comprises: preprocessing the characteristic spectral band to reduce redundant information and / or noise in the spectrum.

[0033] According to the present invention, preferably, the pretreatment method is selected from the second-order differential and / or the first-order differential, and more preferably the second-order differential with a window width of 11-21 (such as 11, 13, 15, 17, 19, 21). The inventors of the present invention further discovered that the use of the above-mentioned pretreatment method, whether for hydrogenated liquid samples or oxidized liquid samples, can further ensure that more effective information of the corresponding hydrogen efficiency or oxygen efficiency is obtained, further improving the accuracy of the results obtained by the subsequent prediction model.

[0034] Among them, the random forest algorithm selected in step (3) is a fusion classification algorithm that includes many decision trees and voting strategies. It belongs to an integrated algorithm and is a natural nonlinear modeling tool that can be used for classification or regression analysis. The inventors of the present invention have found in their research that, compared with other algorithms, such as the partial least squares algorithm and linear modeling algorithm, the random forest algorithm used to construct the prediction model of the present invention has a good tolerance for outliers and noise, and is not prone to overfitting. In particular, the obtained model has a high prediction accuracy rate in determining the hydrogenation efficiency of the hydrogenated liquid and the oxidation efficiency of the oxidizing liquid. As for the random forest algorithm itself, it is a common algorithm. Those skilled in the art are also aware of the principle, and the above algorithm has been open sourced for application. For its specific content, please refer to the description in Fang Kuangnan; Wu Jianbin; Zhu Jianping; Xie Bangchang. A review of random forest method research [J]. Statistics and Information Forum, 2011, 26(03): 32-38. The model construction using the random forest algorithm as above can be carried out in MATLAB.

[0035] In the Random Forest (RF) algorithm, you can also control the ntree (generally referring to the number of sampling training) and mtry (generally referring to the number of features selected for each sampling training) parameters. ntree can be set to 100-500, especially 300-400; mtry can be set to 190-380, especially 230-300.

[0036] According to the present invention, preferably, in step (4), the reaction liquid to be tested is a hydrogenation liquid with unknown hydrogenation efficiency, or an oxidation liquid with unknown oxidation efficiency.

[0037] It is understood that in step (4), the characteristic spectral bands are obtained in the same manner as for the standard hydrogenated liquid, and corresponding preprocessing is performed to obtain corresponding input variables, which are then substituted into the prediction model. If the reaction liquid to be tested is a hydrogenated liquid, the result obtained is the hydrogenation efficiency; if the reaction liquid to be tested is an oxidizing liquid, the result obtained is the oxidation efficiency.

[0038] The present invention will be described in detail below through examples.

[0039] In the following examples, the hydrogenation liquid and the oxidation liquid were obtained during the production of hydrogen peroxide by the anthraquinone process.

[0040] In step (1) of the following examples, the hydrogenation efficiency of the standard hydrogenating solution is determined by first oxidizing with oxygen and then titrating with potassium permanganate, and the oxidation efficiency of the standard oxidizing solution is determined by titrating with potassium permanganate. The hydrogenation efficiency and oxidation efficiency obtained in this way are their respective measured values.

[0041] The instrument used to collect near-infrared spectra was an Antaris II near-infrared spectrometer (Thermo Fisher Scientific).

[0042] The operations after spectrum acquisition were performed in MATLAB.

[0043] Example 1

[0044] To illustrate the method provided by the present invention

[0045] (1) 124 hydrogenation liquids and 126 oxidation liquids, a total of 250 samples, were obtained, and their corresponding measured values ​​were obtained. The measured values ​​of hydrogenation efficiency were distributed in the range of 8.37-13.33 g / L, and the measured values ​​of oxidation efficiency were distributed in the range of 7.42-9.39 g / L. The difference between every two adjacent hydrogenation efficiency values ​​(or every two adjacent oxidation efficiency values) was in the range of 0.01-0.61 g / L).

[0046] The samples were injected into cuvettes (optical path length 2 mm) until the cuvettes were filled to two-thirds of their capacity. The cuvettes were sealed with sealing film and placed in a temperature-controlled sample cell holder for spectrum acquisition. The conditions for acquiring near-infrared spectra included: a temperature of 25°C and a wavenumber range of 3500-10000 cm -1 , with a resolution of 8cm -1 , scanned 128 times.

[0047] (2) For the near-infrared spectrum obtained above, select the characteristic spectral band 4556-7596cm-1 . And perform the second-order differential of each characteristic spectral band with a window width of 19.

[0048] (3) For the above 250 samples, the random forest algorithm was used. The characteristic spectral band after the second-order differential of each sample was used as the input variable of the random forest algorithm, and the measured value of the hydrogenation efficiency or the measured value of the oxidation efficiency corresponding to each sample was used as the output variable. ntree was set to 400, and mtry was set to 253 to construct the prediction model M.

[0049] (4) Take 46 samples to be tested, including 20 hydrogenated liquids and 26 oxidized liquids, obtain near-infrared spectra using the method in step (1), and process them according to step (2) to obtain characteristic spectral bands after second-order differentiation. Substitute each characteristic spectral band into the prediction model M obtained in step (3) to obtain the corresponding calculated value.

[0050] In addition, in order to verify the accuracy of the prediction model, the measured values ​​of the hydrogenation efficiency or oxidation efficiency corresponding to each of the 46 samples were also obtained.

[0051] The measured and calculated values ​​of the 46 samples, as well as the deviation between the two (calculated value minus measured value) are shown in Table 1. In addition, the root mean square error of prediction (RMSEP) and correlation coefficient (R) are used to evaluate the performance of the prediction model M, where

[0052]

[0053] Among them, n is 46, y i is the measured value of the i-th sample to be tested, is the calculated value of the i-th sample to be tested.

[0054]

[0055] Among them, n is 46, y i is the measured value of the i-th sample to be tested, is the calculated value of the i-th sample to be tested, is the average value of the measured values ​​of 46 samples. Through calculation, we can get R=0.931.

[0056] Table 1

[0057]

[0058]

[0059] In addition, a correlation diagram is drawn using the measured values ​​(x-axis) and calculated values ​​(y-axis) of the 46 samples in the validation set. Figure 1 (where R is the correlation coefficient).

[0060] It can be seen that the method provided by the present invention can quickly, simply and accurately predict the hydrogen efficiency of the hydrogenation liquid and the oxygen efficiency of the oxidation liquid in the hydrogen peroxide production process, and the prediction results at various concentrations are relatively accurate and have high accuracy.

[0061] Example 2

[0062] Used to evaluate the repeatability of the method provided by the present invention

[0063] Take one sample of each of the hydrogenated liquid or oxidized liquid to be tested, repeat the near-infrared spectrum measurement four times according to step (1) in Example 1, and then process according to step (2) in Example 1. The characteristic spectral band of each sample after the above processing is used as an input variable and substituted into the prediction model M to obtain the four results (calculated values) for each sample in the four parallel calculations, as shown in Table 2. The relative standard deviation is calculated as follows:

[0064]

[0065] Where S represents the standard deviation of the calculated values, represents the average value of the sample calculation, i = 1, 2, ..., n, n represents the number of samples, x i Represents the calculated value of the i-th sample.

[0066] Table 2

[0067] Number of analyses Hydrogenation efficiency of hydrogenated liquid (g / L) Oxidation efficiency of oxidizing solution (g / L) 1 9.18 8.39 2 9.15 8.36 3 9.14 8.37 4 9.12 8.36 average value 9.148 8.370 Relative standard deviation 0.27％ 0.17％

[0068] As shown in Table 2, the relative standard deviations of the four predicted values ​​of the hydrogenation liquid hydrogen efficiency and the relative standard deviations of the four predicted values ​​of the oxidation liquid oxygen efficiency by the method of the present invention are both low. Therefore, the method provided by the present invention has good accuracy and repeatability for the hydrogenation efficiency of the hydrogenation liquid and the oxidation efficiency of the oxidation liquid to be measured. This shows that the method provided by the present invention has high repeatability and good stability.

[0069] Example 3

[0070] The method of Example 1 is followed, except that ntree is set to 60 and mtry is set to 152. The results are shown in Table 3.

[0071] Table 3

[0072]

[0073]

[0074] It can be seen that Example 1 has better accuracy.

[0075] Comparative Example 1

[0076] The model was established according to the method of Example 1, except that the random forest algorithm was replaced with the partial least squares algorithm. The results are shown in Table 4.

[0077] Table 4

[0078]

[0079]

[0080] It can be seen that the accuracy of the model obtained in this way is poorer than that of the solution provided by the present invention.

[0081] The preferred embodiments of the present invention have been described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, various simple variations of the technical solution of the present invention may be made, including combining the various technical features in any other appropriate manner. These simple variations and combinations should also be regarded as disclosed in the present invention and fall within the scope of protection of the present invention.

Claims

1. A method for simultaneously determining the hydrogenation efficiency of a hydrogenating liquid and the oxidation efficiency of an oxidizing liquid in hydrogen peroxide production, characterized in that: The method includes: (1) obtaining a plurality of standard hydrogenation solutions with known and different hydrogenation efficiencies, and a plurality of standard oxidation solutions with known and different oxidation efficiencies; and collecting near-infrared spectra of the above standard solutions; (2) Select the characteristic spectral band of the above near-infrared spectrum; (3) using a random forest algorithm, taking the characteristic spectral band obtained in step (2) as an input variable and the corresponding hydrogenation efficiency and oxidation efficiency obtained in step (1) as output variables, and constructing a prediction model between the input variables and the output variables; (4) Obtaining the reaction liquid to be tested, collecting a near-infrared spectrum and obtaining the corresponding characteristic spectral band, and substituting it into the prediction model to obtain the hydrogenation efficiency or oxidation efficiency of the reaction liquid to be tested.

2. The method according to claim 1, wherein In step (1), the hydrogenation efficiency of the standard hydrogenation solution and the oxidation efficiency of the standard oxidation solution are each independently 5-16 g / L.

3. The method according to claim 1 or 2, wherein: In step (1), the hydrogenation efficiency of the standard hydrogenation liquid and the oxidation efficiency of the standard oxidation liquid are each independently 7-14 g / L.

4. The method according to claim 1, wherein In step (1), the total amount of the standard hydrogenation liquid and the standard oxidation liquid is not less than 100.

5. The method according to claim 1 or 4, wherein In step (1), the total amount of the standard hydrogenation liquid and the standard oxidation liquid is 150-350.

6. The method according to claim 1, wherein In step (1), the conditions for obtaining the near-infrared spectrum include: temperature of 12-62°C; wave number range of 3500-12000cm -1 ; Resolution is 2-16cm -1 .

7. The method according to claim 1 or 6, wherein: In step (1), the conditions for obtaining the near-infrared spectrum include: temperature of 20-30°C; resolution of 6-10 cm -1 .

8. The method according to claim 1, wherein In step (2), the characteristic spectrum band is between 4000-8000cm -1 , preferably 4556-7596cm -1 .

9. The method according to claim 1 or 8, wherein Before performing step (3), the method further includes: preprocessing the characteristic spectrum band to reduce redundant information and / or noise in the spectrum.

10. The method according to claim 9, wherein: The preprocessing method is selected from the second-order differential and / or the first-order differential, preferably the second-order differential with a window width of 11-21.

11. The method according to claim 1 or 10, wherein: In step (4), the reaction liquid to be tested is a hydrogenation liquid with unknown hydrogenation efficiency, or an oxidation liquid with unknown oxidation efficiency.

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