The effect of the textural properties of bituminous coal chars on NO emissions

NO is the primary product of the oxidation of char nitrogen, and in some co mbustion processes the NO can be reduced on the char surface to give N2O an d/or N-2 In this study a range of bituminous coals (low, medium and high vo latile matter content) were pyrolysed in a fixed bed reactor at various hea ting rates. Textural characterisation was carried out by measuring true (He ) and apparent (Hg) densities and N-2 (-196 degrees C) and CO2 (0 degrees C ) adsorption isotherms. Pore volume distributions and surface areas were ob tained for the chars studied. A thermogravimetric analyser coupled to a qua drupole mass spectrometer (TG-MS) was used to study the combustion behaviou r of the samples and the nitrogen compounds evolved during temperature-prog rammed combustion. Results are discussed in terms of the influence of both textural properties and reactivity on NO emissions and on the heterogeneous reduction of NO. (C) 1999 Elsevier Science Ltd. All rights reserved.