KrevelenMechanismus

Krevelen mechanism is a conceptual model used in geochemistry, petroleum science, and related fields to describe how organic matter evolves chemically during oxidation and thermal maturation. The mechanism is named after the Dutch chemist Dirk W. Krevelen and is often discussed in connection with the Krevelen diagram, which plots hydrogen-to-carbon and oxygen-to-carbon ratios to track changes in composition.

Core idea and features of the mechanism are that oxidation and weathering processes lead to dehydrogenation (loss of hydrogen) and concurrent incorporation of oxygen into the organic matrix, forming oxygen-containing functional groups such as carbonyls, carboxyls, and hydroxyls. As a result, the H/C ratio tends to decrease while the O/C ratio increases, producing characteristic trajectories in plots of H/C versus O/C that are used to interpret maturation or degradation stages in coal, kerogen, and related materials.

Applications and implications of the Krevelen mechanism include helping researchers assess the degree of thermal maturation or oxidation, compare different fossil fuels and precursors, and model qualitative shifts in product distributions during weathering, combustion, or diagenesis. It provides a framework for understanding broad trends in elemental composition without prescribing exact reaction pathways.

Limitations of the model are that it remains a simplification. Real systems involve many parallel and competing reactions, material heterogeneity, and environment-dependent kinetics, so the mechanism describes general trends rather than a single universal sequence of steps. Despite its simplifications, the Krevelen mechanism remains a widely used heuristic in interpreting changes in fossil organic matter. See also Krevelen diagram.