Accession Number : AD0639659

Title :   THE ADSORPTION OF CARBON DIOXIDE ON CARBON SOLIDS. PART 1 - GRAPHITE AND DIAMOND AT 0 C.

Descriptive Note : Interim rept.,

Corporate Author : NAVAL RESEARCH LAB WASHINGTON D C

Personal Author(s) : Deitz,V. R.

Report Date : 11 JUL 1966

Pagination or Media Count : 18

Abstract : The high-temperature physical adsorption of carbon dioxide (<<1% coverage) was measured on a number of relatively well defined carbon solids. The results provide an experimental means to differentiate between two arrays of adsorption sites that originate in the strong anisotropy of the graphite structure. The adsorption isotherms at 0 C indicate two distinct regions of surface coverage that are separated by a wide plateau. The adsorption at very low pressures (<0.01 torr) is considered to correspond to high-energy adsorption on an array of edge carbon atoms in the prism faces; the additional adsorption at higher pressures takes place at sites of lesser energy in the more abundant basal planes. Similar behavior was observed for graphitized carbon black FT (2700 C), nmineral graphite, an annealed pyrolytic graphite, and a deashed heat-treated (1500 C) coconut charcoal. In contrast, the adsorption of carbon dioxide on purified natural-diamond fragments followed a simple Langmuir isotherm compatible with the known isotropic structure of diamond. The amounts adsorbed expressed per unit area bring out similarities among the carbon solids that are characteristic of graphite. The large adsorption on the coconut charcoal appears due only to the large area that is essentially basal plane in behavior. There is evidence that the pyrolytic graphite has a porosity that may be invaded more completely by carbon dioxide than by krypton. (Author)

Descriptors :   (*CARBON DIOXIDE, ADSORPTION), (*GRAPHITE, SORPTION), (*DIAMONDS, SORPTION), SURFACE PROPERTIES, THERMODYNAMICS, CHEMISORPTION, CARBON BLACK, CHARCOAL, PYROLYTIC GRAPHITE, POROSITY

Subject Categories : Industrial Chemistry and Chemical Processing
      Physical Chemistry
      Life Support Systems

Distribution Statement : APPROVED FOR PUBLIC RELEASE