NARROW PORE DISTRIBUTION FORMED IN STEAM AND CO2 GASIFIED COKES OF DIFFERENT ORIGIN

A new high resolution sorption (HRS) technique has been employed to characterize steam and/or CO//2 gasified petroleum cokes, coal chars, and carbon derived from peat and bone char. A lignite gasified by mild oxidation in steam was also studied. All samples show a narrow pore feature centered at 3. 9 nm diameter. High pressure mercury porosimetry of a petroleum coke gasified in a fluidized bed at temperatures greater than 900 degree C confirm the HRS analysis. The authors propose that a primary structural unit, analogous to a micelle or a spherulitic polymer micro domain, forms during the coke formation process. This unit is 4 nm in diameter. Gasification attacks these structural units, generating a narrow pore structure within the coke. In other work, gasification of carbon blacks by mild oxidation attacks the center of the particle and proceeds to the exterior of the spherulitic structure. Such a process would account for the generation of narrow pores within a coke following gasification in steam and/or CO//2.