High‐temperature adsorption of alkali vapors on solid sorbents

W. A. Punjak, M. Uberoi, F. Shadman

Research output: Contribution to journalArticlepeer-review

89 Scopus citations


Vapors of alkali metal compounds can be removed from coal combustion and gasification flue gases using high‐temperature aluminosilicate sorbents. The fundamentals of alkali adsorption on kaolinite, bauxite, and emathlite are compared and analyzed both experimentally and through theoretical modeling. The results show that the process is not a simple physical condensation, but a complex combination of diffusion and reaction. The kinetics of adsorption on these sorbents have similarities: the process is diffusion‐influenced, the rate decreases with time, and there is a final saturation limit. There are, however, differences in reaction mechanisms leading to potentially different applications for each sorbent. In adsorbing alkali chloride vapors, kaolinite and emathlite release all the chlorine back to the gas phase while bauxite retains some of the chlorine. Moreover, the products of reaction with emathlite have a melting point significantly lower than those for kaolinite and bauxite. Therefore, emathlite is more suitable for lower‐temperature sorption systems downstream of the combustors/gasifiers, while kaolinite and bauxite are suitable as in‐situ additives.

Original languageEnglish (US)
Pages (from-to)1186-1194
Number of pages9
JournalAIChE Journal
Issue number7
StatePublished - Jul 1989

ASJC Scopus subject areas

  • Biotechnology
  • Environmental Engineering
  • Chemical Engineering(all)


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