Liquid-phase colour-spectrum quantitative analysis method for cyclohexane carboxylic-acid sulfoacid in process system for producing caprolactam by methylbenzene method

Abstract

The invention discloses a toluene-cyclohexane carboxylic acid-acid liquid chromatography system quantitative analysis method in process of caprolactam production. Its technical features are: (1)Do toluene-cyclohexane carboxylic acid-acid extraction and preparation in cyclohexane carboxylic acid containing sulfonate system by the way of extraction and adsorption, elution, extraction and the crystalline means. The purity of samples from the cyclohexane carboxylic acid-acid >= 98%, absorbents and extract the raw materials are easy to get, adsorption and elution process is simple and easy to operate; (2)Using of the 1H and 13C NMR spectral analysis. FT-IR, UV and LC AAS analysis for Cyclohexane carboxylic acid acid qualitative and quantitative analysis, and the analysis is reliable qualitative and quantitative analysis; (3)Adapting to a complex system of cyclohexane carboxylic acid-acid liquid chromatography quantitative analysis method, the analysis method can separate cyclohexane carboxylic acid-acid from various other components, and have an appropriate response signal, and analyze the harsh conditions, the results of the analysis accuracy and reproducibility, analysis is quick, sample handling is simple.

Description

technical field [0001] The invention relates to a liquid chromatography quantitative analysis method of cyclohexanecarboxylic acid sulfonic acid. Background technique [0002] The production of caprolactam by the toluene method is a method developed by the Italian SNIA Viscosa company in 1960 to produce caprolactam using toluene as a raw material. The advantages of the toluene method are short process, safe operation, and low initial cost, which is suitable for countries with abundant toluene. . But there are some deficiencies at the same time. In addition to the many by-product sulfuric acid and pollution to the atmospheric environment, the selectivity and yield of producing caprolactam by cyclohexane carboxylic acid are not as high as producing caprolactam by methods such as cyclohexanone oxime. The main reason is that There are sulfonation side reactions in the premixed reaction of cyclohexane carboxylic acid. The side reaction is mainly the sulfonation reaction at the ...

AI Technical Summary

Problems solved by technology

From the perspective of production practice and scientific research, the influence on the selectivity and yield of caprolactam produced by SNIA lies in the lack of sufficient understanding of each reaction mechanism and influencing factors, and the current analysis conditions do not have a clear understanding of the amount of cyclohexanecarboxylic acid sulfonic acid produced. Accurate instrumental qualitative and quantitative analysis of by-products, such as the amount of cyclohexanecarboxylic acid sulfonic acid generated in the premixed reaction of cyclohexanecarboxylic acid, and the process conditions that affect the ratio of main and side reaction products have no quantitative analysis and understanding. Qing, how to establish a set of liquid chromatography quantitative analysis method of cyclohexane carboxylic acid sulfonic acid, according to the qualitative and quantitative analysis results of cyclohexane carboxylic acid sulfonic acid and other by-products, find the primary and secondary components of the premixed reaction of cyclohexane carboxylic acid The distribution of reaction products and the change of cyclohexanecarboxylic acid sulfonic acid in the follow-up process are of great significance for optimizing the pre-mixed reaction process conditions, reducing the generation of by-product cyclohexanecarboxylic acid sulfonic acid, etc., and improving the reaction yield of caprolactam produced by the toluene method. very important

In view of the advantages and disadvantages of producing caprolactam by the toluene method, the National Natural Science Foundation of China established a project in 2003 (Project No. 20233040, a key research project of the National Natural Science Foundation of China) to conduct key scientific and technological research on "Key Technology Innovation and Basic Research for Environmentally Friendly Production of Caprolactam" , the main research of the key research is the environment-friendly production process, which does not involve the establishment of the analysis method of cyclohexane carboxylic acid sulfonic acid in the system. At the same time, in the existing patents and documents, there is no related cyclohexane in each system of the SNIA process. The report of the instrument quantitative analysis method of carboxylic acid sulfonic acid and acidic by-product only has the chemical analysis method to cyclohexane carboxylic acid sulfonic acid in neutral and alkaline system, and the chemical analysis method of cyclohexane carboxylic acid sulfonic acid adopts The neutralization titration method with two equivalence points, this method has limitations and serious deficiencies through production practice and scientific research applications: the analysis conditions are quite harsh, multiple extractions are required, the processing steps are cumbersome, the consumption of reagents is large, etc. It is very difficult to judge when the point, the analysis time is long, the analysis results are not repeated and the analysis deviation is large, it is even more unsuitable for the acidic system, and cannot meet the needs of production and scientific research. The establishment of an accurate and rapid cyclohexine that is suitable for various systems in the SNIA process The liquid chromatographic instrument quantitative analysis method of alkane carboxylic acid sulfonic acid and other components, and the process of producing caprolactam by the p-toluene method are very necessary in guiding industrial production and scientific research

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