Characterization of porosity via secondary reactions. Quarterly technical progress report, 1 April 1995--30 June 1995

Abstract

In the previous quarterly report (DE-FG22-91PC91305-14), we presented an analysis of small angle neutron scattering (SANS) data obtained for Pittsburgh {number_sign}8 coal char. These samples exhibited considerable scattering. However, when the voids between the particles were filled with a liquid that had the same neutron scattering density as the carbon, the amount of scattering was reduced by more than two orders of magnitude. Analysis of the scattering invariant in terms of surface area showed that the char had very little porosity. To date this has been the only contrast matching SANS study of carbon and the first recognition that interparticle scattering effects are important. In this report, we focus on SANS data obtained for a very different char--a phenolic resin char (PRC). The following was accomplished during the reporting period: contrast matching, SANS data obtained for resin char has been analyzed in detail. Conclusions derived from this analysis include: contrast matching SANS has been demonstrated to be a useful technique for monitoring the activation/gasification process. It is demonstrated how this technique can be used to address such important issues as the role of ``closed`` vs ``open`` porosity, and interparticle scattering. It has been used here to establish that the development of porosity in phenolic resin char upon gasification in air proceeds primarily by ``opening `` or originally ``closed`` porosity. This is quite different than the behavior of Pittsburgh {number_sign}8 coal char. for example, as presented in the previous quarterly report.