Investigation of the thermal degradation of a cation exchange resin in aqueous medium

A strong acid cation resin consisting of a styrene-divinylbenzene copolymer matrix with sulfonic acid functional groups was studied in aqueous solution at high temperatures and pressures in a Teflon-lined Parr pressure reactor to mimic power plant conditions. Gas Chromatography-Mass Spectroscopy and High Performance Liquid Chromatography were used to identify and quantitate the resin degradation products. The effects of two metal alloys--Inconel 600 and Carpenter 20--on the degradative behavior of the resin and the effect of the resin and its degradation products on these alloys were also investigated. In the environment within the Parr pressure reactor, thermal, oxidative, mechanical, and solvent forces acted on the resin producing a variety of products. Analysis of the sample solutions showed that trace amounts of polymeric and non-polar aromatic material such as acetophenone, styrene, and benzaldehyde were produced. Part-per-million concentrations of polar aromatic compounds, principally p-sulfobenzoic acid, were also found in solution. In agreement with literature studies, sulfate was the major degradation product. It was found at the percent concentration levels. The resin and its degradation products increased the corrosion rates of the alloys. Carpenter 20 was more affected because of its composition. The large quantities of metal ions that were dissolved from the alloys under the high temperature and pressure conditions suppressed the formation of sulfate and increased the production of organic material from the cation exchange resin.