Characterizadtion of porosity via secondary reactions. Quarterly technical progress report, 1 July 1994--30 September 1994

The following was accomplished during the reporting period: Comparisons between porosity characterization data obtained from nitrogen adsorption isotherms, and that revealed by CO and CO{sub 2} temperature programmed desorption (TPD) spectra were performed for Pittsburgh {number_sign}8 coal char samples prepared at various degrees of burn-off, ranging from 0--72% burn-off, in 0.1 MPa oxygen at 470{degrees}C. Conclusions derived from these analyses include: The CO TPD spectra correlate the development of the microporosity; and the CO{sub 2} spectra correlate the development of the larger, external porosity. This behavior is the same as we have observed for Wyodak coal char. This behavior is currently attributed to the restriction of formation of the larger C0{sub 2}-liberating oxygen surface complexes (e.g., lactones, carboxylic acid anhydrides) to the larger, external porosity, while the smaller CO{sub 2}-liberating complexes (e.g., carbonyls, semi-quinones) form on the surfaces of all they porosity, but since the microporosity accounts for the bulk of the surface area, the latter correlates the microporosity quite well. Together with the Wyodak coal char results, these data represent the first time that this particular connection has been made between porosity development and TPD spectra