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CO 2 ‐Catalyzed Surface Area and Porosity Changes in High‐Surface‐Area CaO Aggregates
Author(s) -
BERUTO DARIO,
BARCO LUIGI,
SEARCY ALAN W.
Publication year - 1984
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/j.1151-2916.1984.tb19644.x
Subject(s) - porosity , diffusion , adsorption , limiting , surface diffusion , specific surface area , ion , materials science , catalysis , mineralogy , chemical engineering , decomposition , chemistry , thermodynamics , composite material , organic chemistry , mechanical engineering , physics , engineering
The changes in surface area and mesoporosity in aggregates of ∼0.01 μm cross‐section CaO particles when heated in CO 2 at 686°C were determined from N 2 adsorption isotherms. Initially, the surface area decreases rapidly with little change in porosity. When the surface area has decreased below ∼90 m 2 /g, surface area and porosity variations become consistent with expectations for coarsening by grain‐boundary or bulk diffusion. The initial rapid decrease in surface area must result from CO 2 ‐catalyzed surface diffusion, but the data suggest that surface diffusion is not rate‐limiting. The rate‐limiting step may be reaction of CO 2 to form surface CO 3 2‐ ions or decomposition of these ions to O 2‐ ions and CO 2 gas.