Comparison of micro- and macropore evolution of coal char during pyrolysis

• Published in: Fuel (Guildford) 2020-09, Vol.275, p.117845, Article 117845
• Main Authors: Wedler, Carsten, Span, Roland, Richter, Markus
• Format: Article
• Language: English
• Subjects: Adsorption; Bituminous coal; Carbon dioxide; Coal; Colombian coal; Dubinin-Astakhov model; Evolution; Gasification; Micropore analysis; Morphology; Nuclear fuels; Porosity; Pyrolysis; Solid fuels; Temperature
• ISSN: 0016-2361; 1873-7153
• DOI: 10.1016/j.fuel.2020.117845

To characterize the changing morphology of a solid fuel with ongoing pyrolysis and gasification, we investigated the evolution of the micropore structure of a high volatile bituminous Colombian coal. In a previous study, Colombian coal was pyrolyzed in a laminar drop tube reactor, whereby the residence time, the pyrolysis temperature, and the gas atmosphere were varied. Here, we present new experimental data on the micropore structure of those chars and compare them with their meso-/macropore analysis. The micropores were investigated using volumetric adsorption measurements with CO2 at a temperature of T = 273.15 K. Micropore volumes, surface areas and homogeneities were determined on the basis of the adsorption isotherm model of Dubinin-Astakhov and, thus, a comprehensive analysis of the pore structure is presented in this work. Differences in the evolution of micropores and meso-/macropores were observed. The dry coal and the chars pyrolyzed for residence times of around 45 ms are dominated by micropores, but as pyrolysis progresses this dominance decreases, since micropores are expanding to mesopores. Nevertheless, the formation of new narrow micropores during the pyrolysis could be observed as well.