Method for detecting purity of phthalic anhydride in phthalic anhydride slag

Abstract

The invention relates to a method for detecting the purity of phthalic anhydride in phthalic anhydride slag. The method comprises the following steps of dissolving the phthalic anhydride slag to be detected in a polar solvent to prepare a sample solution; standing the sample solution until the insoluble substances are completely precipitated, taking the supernate, injecting the supernate into a gas chromatograph, and detecting the mass percent of the phthalic anhydride in the sample solution; extracting the insoluble substances and weighing to obtain the mass of the insoluble substances, and obtaining the mass of the phthalic anhydride residues dissolved in the polar solvent according to the mass of the insoluble substances; and obtaining the purity of the phthalic anhydride in the phthalic anhydride slag according to the mass of the insoluble substances insoluble in the polar solvent, the mass percent of the phthalic anhydride dissolved in the polar solvent and the mass of the phthalic anhydride slag. According to the method, the insoluble substances insoluble in the solvent are independently extracted and independently weighed, so that the detection precision is improved, the operation is simple, the analysis time is short, the repeatability is good, and the detection of the purity of the phthalic anhydride in the phthalic anhydride residues with relatively lower purity can be met.

Description

technical field [0001] The invention belongs to the technical field of chemistry, and in particular relates to a gas chromatography detection method for detecting the purity of phthalic anhydride in phthalic anhydride residues. Background technique [0002] In the actual production process of industrial naphthalene oxidation to phthalic anhydride, due to the existence of various impurities and the occurrence of side reactions, a by-product of phthalic anhydride residue containing dozens of organic substances is produced. The content of phthalic anhydride in the by-products has a direct impact on the process control and profit of the production enterprise. [0003] The current national standard GB / T 15336-2013 "Phthalic Anhydride" 6.7 provides a method for the determination of the purity of phthalic anhydride. However, this method is only aimed at high-purity phthalic anhydride products, and impurities that are insoluble in polar solvents cannot be directly obtained through ...

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Problems solved by technology

However, this method is only aimed at high-purity phthalic anhydride products, and impurities that are insoluble in polar solvents cannot be directly obtained through chromatographic detection. Therefore, the detection of phthalic anhydride content in phthalic anhydride residues cannot be based on this standard. direct detection

The neutralization titration method for the determination of the purity of phthalic anhydride given in 5.8 of the national standard GB / T 15336-2006 "phthalic anhydride" has been invalidated. The distillation time is too long, the operation is cumbersome, and because the sample color is darker , the color change of the titration end point is judged by the naked eye with a large error, which cannot meet the repeatability requirements in the standard

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