Rapid determination of products of phenol hydrogenation in a supercritical water system using headspace gas chromatography

Abstract

This paper reports a headspace analysis technique for the determination of products, i.e., cyclohexanone (CE) and cyclohexanol (CL), of phenol hydrogenation in a supercritical water reaction system (SWRS) with water removal by hydrate formation. An addition of anhydrous calcium chloride leads to water absorption resulting in crystal water; thus, the samples can be quantitatively measured without the influence of water. After achieving equilibrium at 150 • C and maintaining it for 5 min, the obtained results showed a relative standard deviation of less than 5.3 % and the recovery ranged from 93 % to 104 %. The presented method is simple and accurate for the analysis of CL, CE and phenol in samples from phenol conversion in SWRS.

Determination of highly volatile compounds in fresh onion (Allium cepa L.) by room‐temperature enrichment headspace‐trap coupled to cryotrapping GC–MS

“…However, the memory effects of Nafion driers have always affected the method . For static HS‐GC, the conversion of water into a solid crystalline hydrate form using appropriate hygroscopic salts was a usual method to reduce the amount of water transferred to the column . This method was insufficient for removing large amounts of water vapor from high‐water‐content‐samples .…”