Characterization of porosity via secondary reactions. Quarterly technical progress report, 1 January 1995--31 March 1995

The following was accomplished during the reporting period: Small angle neutron scattering (SANS) data were obtained for Pittsburgh {number_sign}8 coal char samples at various levels of bum-off at the Intense Pulsed Neutron Source (IPNS) of the Argonne National Laboratory on the small angle diffractometer (SAD) instrument. The Pittsburgh {number_sign}8 samples complement previous SANS data obtained for non-mineral matter-containing phenol-formaldehyde resin char samples. A contrast-matching technique involving the comparison of scattering data for ``dry`` samples with data from the same samples saturated in deuterated toluene, show that the ungasified Pittsburgh {number_sign}8 char has very little closed porosity and, consequently, that pore development during gasification proceeds by the creation of new pores. In the early stages of gasification (< 4.5% burn-off) a pore system with significant microporosity is produced. In later stages of gasification (4.5%--13.5% bum-off) the tendency is to open these micropores, producing a pore system with a broad size distribution. Nitrogen adsorption isotherms (77K) were determined for all the same samples for which SANS data were obtained in order to provide a corroborative check on their porosity characteristics