Nanostructure and oxidation reactivity of carbons prepared by rapid heating

This dissertation describes the development of a new digital image processing algorithm for HRTEM micrographs, including the definition of new structure parameters and a new transient thermal treatment apparatus for investigating thermal deactivation in the oxidation reaction of carbons. Char nanostructural transformations during combustion were quantitatively characterized and the ordering mechanism inferred. New parameters were developed for distinguishing short and long range order. Long range order was further classified as statistical or mesophasic, depending on the formation mechanism. Among bituminous coals, the oxidation reactivity was highly correlated with several structural parameters extracted from the fringe images.In addition, thermal deactivation at high heating rates and short heat treatment times was measured for a large number of organic precursors, and the trends were qualitatively explained. Reactivity of carbons to oxygen showed a strong dependence on heat treatment temperature and precursor. The char reactivities from various precursors differed by 103, and the difference became smaller (&sim101.5) at a heat treatment temperature (HTT) of 2500°C. From raw to heat treated chars, the degree of deactivation was on the order of 104 for lignite and 10 for Pocahontas chars. As shown in thermal deactivation trend among precursors, the higher the initial reactivity, the greater the typical extent of deactivation. An exception to this trend was an anthracite, Lykens valley...