The role of carbon dioxide and water in the degradation of zeolite 4A, zeolite 13X and silica gels

Abstract

The degradation of desiccants is important in designing natural gas conditioning processes. Previous studies have focused on the effect of changes in regeneration gas water content, regeneration temperature and number of thermal cycles. However, less is known about how other components impact the lifespan of desiccants over thousands of thermal cycles. Herein we present results on how desiccant degradation is influenced by CO₂ in a process fluid. Increasing the CO₂ concentration resulted in less degradation across unsupported zeolite 4A, zeolite 13X and silica gels. Additionally, higher water concentrations in the regeneration gas resulted in a decrease in the degradation at the same CO₂ concentration. For zeolite 13X, the surface area and pore volumes were larger in the samples subjected to greater CO₂ concentrations. For silica gels, a higher capacity for water adsorption after 5000 thermal swing adsorption cycles was observed in samples with a lower concentration of surface silanol groups.