Simulating the Geological Fate of Terrestrial Organic Matter: Lignin vs Cellulose
Léa Atmani, Pierre-Louis Valdenaire, Roland J.‐M. Pellenq, Christophe Bichara, Henri Van Damme, Adri C. T. van Duin, Franz‐Josef Ulm, Jean‐Marc Leyssale
Abstract
While shale gas has become a major source of energy, a more sustainable recovery requires a better understanding of the gas/kerogen matrix interactions. Here, we use replica exchange molecular dynamics to investigate the geological conversion of two important classes of gas-forming constituents of the terrestrial organic matter: lignin and cellulose. In agreement with results from pyrolysis experiments, we show that lignin produces twice as much kerogen and 5 times more methane than cellulose. In addition, while ex-cellulose kerogen is relatively stiff and almost nonporous, ex-lignin kerogen, despite having a very similar composition and bonding, is an order of magnitude more compliant due to the presence of large micropores. The obtained results can potentially improve the nanoscale brick of bottom-up models of shale gas recovery.