PORPHYRIN-DERIVED AND METALLOPORPHYRIN-DERIVED CARBONS AS MODELS FOR COAL CHAR COMBUSTION AND PYROLYSIS

The pyrolysis and combustion characteristics of carbons prepared by ca rbonization of porphyrin-and metalloporphyrin-containing (or phthalocy anine-and vanadyl phthalocyanine-containing) precursors are reported. All the metals studied-V, Fe, Co and Cu-catalysed the combustion of th e carbons, regardless of heat-treatment temperature. In general, the r eactivities of all the carbons decreased with increasing heat-treatmen t temperature, and a compensation effect on the rate was observed, wit h both the activation energies and the pre-exponential factors decreas ing. The metals have a marked influence on the release of nitrogen spe cies during pyrolysis. Less HCN and CH3CN are released in the volatile s for metalloporphyrin-derived carbons than for porphyrin-derived carb ons. The vanadyl system was also studied for nitrogen release during c ombustion. Less fuel-N is converted to NO and more is converted to N-2 and HCN during combustion of this carbon. (C) 1997 Elsevier Science L td.