ADVANCED COMBUSTION ENGINEERING RESEARCH CENTER

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Sommerfeld, DA

1992

Spectroscopic Studies of Coal Maceral Depolymerization Effected by an Iron-Based Catalyst

Wang, H.P.; Lo, R.; Sommerfeld, D.A.; Huai, H.; Pugmire, R.J.; Shabtai, J.S. and Eyring, E.M.
Fuel, 71(7):723-729, 1992. Funded by US Department of Energy.

Demineralized Hiawatha (Utah) coal was divided into narrow density fractions of resinite and vitrinite macerals using a density gradient centrifugation technique. The distribution of an iron-based catalyst in the coal maceral matrix was studied using an electron probe microanalyser. The data indicate that the iron catalyst is evenly dispersed inside the vitrinite. This uniform dispersion is preserved upon mild (275ºC) hydrotreatment and attendant partial depolymerization of the vitrinite maceral. However, the iron catalyst does not completely penetrate into the resinite maceral matrix due to a lack of microporosity. The small amount of dispersed iron catalyst in the resinite causes some depolymerization of maceral components, e.g. dimers, trimers, or higher polymers, into monomers. Due to the insufficient dispersion of the iron catalyst in the resinite a competing thermal breakdown of the maceral occurs. This apparently involved a partial dehydrogenation reaction that may be favored during the hydrotreatment of resinite.