Activated alumina adsorbent is used as a protective layer, at the inlet of many gas-phase molecular sieve beds. Activated alumina has an exceptionally high volumetric capacity for any liquids that may be present in the feed stream and can hold over 50% of its weight in liquids. It serves to protect the molecular sieve bed from film coating and accelerated coking as a result of hydrocarbon condensates and carryover, potential amine and glycol carryover from upstream processes, and liquid water entrainment.
In addition, activated alumina is a dehydration-grade material with high density that can remove water when not being used for liquids containment. It regenerates more easily than a molecular sieve and thus adds little additional load to the regeneration step in thermal swing applications. Thus, it can be easily added in most applications with minimal changes and will typically require no more than 1 ft. (0.3 meters) of additional bed height.
Additionally, it can be used in the drying of streams such as air, carbon dioxide, carbon monoxide, sulfur hexafluoride, ammonia, hydrogen sulfide, heavy hydrocarbons, gasoline, chlorinated or fluorinated hydrocarbons, or aromatic hydrocarbons. It is most often recommended when complete dryness is not necessary (ppm level water is acceptable) and where high thermal and mechanical resistance is required.