CO2 gasification of Argentinean coal chars: a kinetic characterization

A kinetic characterization of the CO2 gasification of chars from Argentinean low-rank coals, subbituminous (SB) and high volatile bituminous (HVB), is performed by isothermal thermogravimetry. Temperatures in the range 1173–1433 K and CO2 concentrations among 50% and 70% v/v are employed. Experimental data obtained for both chars for the whole range of experimental conditions explored were satisfactorily described by a single master curve. Reactivity differences between chars are discussed in terms of carbon content, microporosity and crystallinity of the char carbonaceous part. In addition, potential catalytic effects of inherent minerals on chars gasification reactivity are examined by demineralizing the chars. For the subbituminous char, catalytic effects due to mineral matter content are detected up to 1333 K, whereas at higher temperatures they become considerably less pronounced. For the bituminous char, reactivity seems to depend more on structural and textural features than on catalysis over the whole range of operating conditions. Intrinsic gasification rates for both chars are properly represented by the well-known random capillary and random pore models (RPM). Recent models based on modifications introduced to the latter are also applied and kinetic data description is discussed.