Early maturation processes in coal. Part 1: Pyrolysis mass balances and structural evolution of coalified wood from the Morwell Brown Coal seam

摘要

In this work, we develop a theoretical approach to evaluate maturationprocess of kerogen-like material, involving molecular dynamic reactive modelingwith a reactive force field to simulate the thermal stress. The Morwell coalhas been selected to study the thermal evolution of terrestrial organic matter.To achieve this, a structural model is first constructed based on models fromthe literature and analytical characterization of our samples by modern 1-and2-D NMR, FTIR, and elemental analysis. Then, artificial maturation of theMorwell coal is performed at low conversions in order to obtain, quantitativeand qualitative, detailed evidences of structural evolution of the kerogen uponmaturation. The observed chemical changes are a defunctionalization of thecarboxyl, carbonyl and methoxy functional groups coupling with an increase ofcross linking in the residual mature kerogen. Gaseous and liquids hydrocarbons,essentially CH4, C4H8 and C14+ liquid hydrocarbons, are generated in lowamount, merely by cleavage of the lignin side chain.