硝酸氧化环己醇合成已二酸中微量苯酚的生成及机理分析

Generation and mechanism of trace phenol during nitric acid oxidation of cyclohexanol into adipic acid

为了探究硝酸氧化环己醇合成己二酸过程中生成微量苯酚的机理及其对己二酸的影响,采用中和萃取的方法处理硝酸氧化环己醇合成己二酸的反应液,并利用气相色谱-质谱(GC-MS)分析萃取液,同时采用同样的处理方法和分析方法对己二酸不同工段的产品进行了处理分析。结果表明:环己醇氧化反应液和不同生产工段的己二酸产品中均检测出了微量苯酚;微量苯酚的生成机理是环己醇在催化剂作用下,于反应体系局部高温区域脱氢而成;微量苯酚易被空气氧化生成苯醌或者其他偶氮化合物最终导致己二酸色度偏高,引起尼龙66盐UV值偏高。

In order to study the generation mechanism of trace phenol during nitric acid oxidation of cyclohexanol into adipic acid and the effect of trace phenol on adipic acid, the reaction solution of nitric acid oxidation of cyelohexanol into adipic acid was treated by neutralization extraction and the extraction solution was analyzed by gas chromatograph-mass spectrometry when adipic acid at different production stages was treated and analyzed by the same method. The results showed that trace adipic acid was detected in the reaction solution of cyclohexanol oxidation and the crude product of adipic acid at different production stages ; the generation mechanism of trace phenol was the local high-temperature dehydrogenation of eyclohexanol reaction system in presence of catalysts; trace phenol was easy to be oxidized into benzoquinone or other azo compounds in air, resulting in the relatively high chroma of adipic acid and the comparably high UV value of nylon 66 salt.