Experimental investigation on the active sites during combustion of aromatic clusters in coals and chars

Abstract

The combustion of aromatic clusters account for major part during combustion of coals or chars, but there is few directly information from experiments about the active sites during combustion of aromatic clusters. Using differential thermal analysis (DTA), nuclear magnetic resonance (NMR), electron spin resonance (ESR), and Raman spectra, coupled with kinetic analyses, the properties and combustion behaviors of different coals and chars are obtained to investigate the active sites. The peak temperatures (Tpeak) of the DTA curves during combustion reflect the properties of active sites from kinetic deduction. The numbers of aromatic rings per unit structure are obtained and are correlated with Tpeak. The amounts of stable radicals and functions obtained from Raman spectra are also correlated with Tpeak. Linear relationship between A(S + A1+A2)/AD and Tpeak−2 can be found, indicating the peripheral parts of aromatic clusters are the active sites. The active sites can be represented quantitatively by A(S + A1+A2)/AD function.