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Method for measuring content of cyclohexanone-oxime by liquid chromatography

A cyclohexanone oxime and liquid chromatography technology is applied in the field of liquid chromatography for determining the content of cyclohexanone oxime in Beckmann rearrangement liquid in caprolactam production, and can solve the problems of complex analysis process, low recovery rate, high formaldehyde toxicity, etc. problems, to achieve the effect of simple analysis steps, high analysis accuracy and less harmful reagents

Active Publication Date: 2011-05-11
CHINA PETROLEUM & CHEM CORP +1
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AI Technical Summary

Problems solved by technology

The main problems of this method are: ①The preliminary treatment of the tested samples is cumbersome
②The analytical results have low precision and poor repeatability, with a standard deviation of 5.0% and a recovery rate of 85%
③ The measurement time is long, which is not conducive to guiding the production of the device
④ Formaldehyde is highly toxic and pollutes the environment
This method can be used for the determination of trace cyclohexanone oxime, good repeatability, and can be used for production process control analysis. However, the analysis process of this analysis method is complicated, the number of reagents used is too large, and the recovery rate is not high, which is about 90%, which is not conducive to improving the production process. Analytical efficiency and analytical quality

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  • Method for measuring content of cyclohexanone-oxime by liquid chromatography

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0015] Example 1 Determination of cyclohexanone oxime content in the reaction solution,

[0016] Because the caprolactam production unit by cyclohexanone oxime method has not been started yet, the amidation reaction product solution of caprolactam production by toluene method is added with cyclohexanone oxime standard reagent to prepare the tested sample solution, and the amidation reaction product solution is a mixture of caprolactam and concentrated sulfuric acid. The measurement steps are:

[0017] (1) Preparation of standard solution: Take 0.0925 g of cyclohexanone oxime chromatographically pure reagent, dissolve it in water, put it into a 100ml volumetric flask, and dilute to the mark with distilled water. Take 5ml from it, add 0.1M NaOH to make PH = 8-9, put it in a 100ml volumetric flask, dilute to the mark with distilled water, and it is A solution. Take 5ml from solution A and place it in a 100ml volumetric flask, dilute to the mark with distilled water, and obtain s...

Embodiment 2

[0023] Embodiment 2 repeatability test

[0024] Take 21.8894g of the amidation reaction liquid, add 0.0306g of cyclohexanone oxime, add ice water and 4M NaOH for hydrolysis and neutralization, weigh 185.57g in total, and have a pH value of 8-9 to prepare 10 samples. Using the standard solution and calibration solution in Example 1, a calibration curve was established according to the steps and instrument conditions in Example 1, and 10 samples were measured. The measurement results are shown in Table 1.

[0025] Table 1 Analysis results of repeatability test

[0026] sample

Embodiment 3

[0027] Embodiment 3 comparative test

[0028] In order to verify the accuracy of the determination of the present invention, the tested samples were prepared with caprolactam, cyclohexanone oxime and different amounts of 50% sulfuric acid. The composition of the prepared samples is shown in Table 2. Accurately weigh the samples in Table 2, hydrolyze with ice water, and neutralize with 4M NaoH to pH=8-9, dilute and make to volume in a 100ml volumetric flask. Using the standard solution and calibration solution in Example 1, establish a calibration curve according to the steps and instrument conditions in Example 1, and measure the sample and calculate the content of cyclohexanone oxime. As a comparison, the tested samples in Table 2 were measured by spectrophotometry at the same time, and the measurement results are shown in Table 3. The results show that the liquid chromatography method of the present invention has a much higher determination accuracy of the trace cyclohexano...

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Abstract

The invention provides a method for measuring the content of cyclohexanone-oxime by liquid chromatography, which comprises the following steps of: adding alkali to regulate pH to be between 8 and 9, preparing standard solution and sample solution by using water as a diluent, and measuring by using a liquid chromatograph with an ultraviolet-visible detector, wherein the wavelength is 210nm, the column box temperature is 25 DEG C, and aqueous solution of acetonitrile is taken as a mobile phase; and after a base line of the chromatograph is stable, measuring the standard solution and the sample solution, namely injecting the standard solution, ensuring that the area change of two-time injected standard solution is less than 1 percent, injecting the sample solution during two-time standard solution injection, and measuring. Analysis accuracy is high, standard deviation is less than 1.0 percent, measuring time is short, and average recovery rate is 97.75 percent; and analysis steps are simple, the labor intensity of testers is low, and the method is safe and environmental-friendly, is used for measuring the content of the cyclohexanone-oxime in Beckmann rearrangement liquid during the production of caprolactam, and also can be used for measuring trace cyclohexanone-oxime in an acidic medium in other processes.

Description

technical field [0001] The invention belongs to the technical field of chemical analysis and relates to a method for measuring the content of cyclohexanone oxime, in particular to a method for measuring the content of cyclohexanone oxime in Beckmann rearrangement liquid in caprolactam production by liquid chromatography. Background technique [0002] The production of caprolactam by cyclohexanone oxime method uses concentrated sulfuric acid or oleum as a catalyst, and the intermediate product cyclohexanone oxime is converted into caprolactam sulfate by liquid-phase Beckmann rearrangement reaction, and then neutralized with ammonia. Cyclohexanone oxime is an intermediate product in the production of caprolactam. The Beckmann rearrangement of cyclohexanone oxime is the main process of caprolactam production. The effect of the rearrangement reaction directly affects the product yield and product quality of caprolactam. The content of cyclohexanone oxime in the rearrangement liq...

Claims

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Application Information

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IPC IPC(8): G01N30/02G01N30/88
Inventor 陈艳芬陈淼邱路刘岚王仲霞高立新
Owner CHINA PETROLEUM & CHEM CORP
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