TY - JOUR N2 - In the paper, on the basis of our studies and the available literature data, a model of changes in the number of active centers corresponding to the structure of the reactive coal particle has been developed. A new distribution function that links the specific surface area of a particle with its porosity and reaction degree has been proposed. An equation for estimation of changes in this parameter during the reaction, on the basis of the initial value, has been presented. In the range of our data and the analysis of the literature data, the model, with satisfactory accuracy, describes internal structural changes of coal and coal char particles. The present results may constitute a basis for complex modelling of coal conversion processes. Based on the results it was found that the total active centres are related to the internal surface area and porosity of the particle. For a specific coal type, this value depends on the porosity, true density and size of the particle. Changes in total active centres, when these structural properties during thermal conversion of coal are considered, are described in equations. L1 - http://journals.pan.pl/Content/84599/PDF/06-paper-Gil.pdf L2 - http://journals.pan.pl/Content/84599 PY - 2011 IS - No 2 June EP - 169 DO - 10.2478/v10176-011-0012-8 KW - coal KW - active centers KW - porosity A1 - Gil, Stanisław A1 - Mocek, Piotr A1 - Bialik, Wojciech PB - Polish Academy of Sciences Committee of Chemical and Process Engineering DA - 2011 T1 - Changes in total active centres on particle surfaces during coal pyrolysis, gasification and combustion SP - 155 UR - http://journals.pan.pl/dlibra/publication/edition/84599 T2 - Chemical and Process Engineering ER -