Effect of the pressure and temperature of devolatilization on the morphology and steam gasification reactivity of coal chars

This document is the Accepted Manuscript version of a Published Work that appeared in final form in Energy and Fuels, copyright © American Chemical Society after peer review and technical editing by the publisher. To access the final edited and published work see https://doi.org/10.1021/ef100877tThe effect of operating conditions (pressure and temperature) on char morphology and structure during coal devolatilization was studied. For this purpose, five different rank coals were selected: a lignite, three bituminous coals, and a semi-anthracite. The coal chars were prepared by devolatilization in a novel pressurized fixed-bed reactor. The pyrolysis experiments were carried out isothermally at temperatures of 800, 900, and 1000 °C and pressures of 1, 5, 10, and 20 atm. The chars obtained from the bituminous coals at elevated pressure experienced a high degree of swelling, whereas those from the lignite and semi-anthracite were hardly affected at all by pressure. The devolatilization temperature did not appear to have any significant effect on char morphology below 1000 °C. The reactivity of the char samples prepared under different pyrolysis conditions was studied by isothermal thermogravimetric analysis at 1000 °C under a steam atmosphere. The chars obtained at elevated pressure were found to be more reactive than those produced at atmospheric pressure. An increase in the pyrolysis temperature led to a decrease in char reactivity.Peer reviewe