Title: Coal gas adsorption/desorption isotherms versus diffusion process

Authors: Cristina Fernanda Rodrigues; Maria Alzira Pimenta Dinis; Manuel João Lemos de Sousa

Addresses: CIAGEB, Global Change, Energy, Environment and Bioengineering RDID&D Unit, Faculty of Science and Technology, Universidade Fernando Pessoa, Praça de 9 de Abril, 349, 4249-004 Porto, Portugal ' CIAGEB, Global Change, Energy, Environment and Bioengineering RDID&D Unit, Faculty of Science and Technology, Universidade Fernando Pessoa, Praça de 9 de Abril, 349, 4249-004 Porto, Portugal ' CIAGEB, Global Change, Energy, Environment and Bioengineering RDID&D Unit, Faculty of Science and Technology, Universidade Fernando Pessoa, Praça de 9 de Abril, 349, 4249-004 Porto, Portugal; Academia das Ciências de Lisboa, Rua da Academia das Ciências, 19, 1249-122 Lisboa, Portugal

Abstract: In the present work, the authors studied two meta-anthracite samples from Douro coalfield (NW of Portugal) in which classical sorption isotherms were carried out, using CO₂ only. Results have demonstrated that whenever the CO₂ is adsorbed in the coal pores/matrix it will be enduringly fixed up to, approximately, pressures of 32 bar in sample A and 34 bar in sample B. Since the gas release process is intensely related to diffusion coefficients, it is crucial to define their evolution on the two analyses reported in this paper. So, during adsorption, diffusion coefficients decrease in sample A from 4.66736E-08 to 1.23490E-09 cm²/sec (6.72 and 48.13 bar) and during desorption they increase from 7.61829E-09 to 1.09908E-08 cm²/sec (45.68 and 11.48 bar). In sample B, diffusion coefficients decrease from 2.47409E-08 to 2.11813E-09 cm²/sec (7.53 and 47.17 bar) in adsorption and increase in desorption from 1.48767E-09 to 2.83736E-08 cm²/sec (42.22 and 7.71 bar).

Keywords: carbon adsorption; desorption; coal gas; CO2; diffusion process; global warming; sorption isotherms; Portugal; carbon dioxide; gas release.

DOI: 10.1504/IJGW.2016.076332

International Journal of Global Warming, 2016 Vol.9 No.4, pp.467 - 485

Received: 22 Feb 2014
Accepted: 07 Dec 2014
Published online: 04 May 2016 *

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