不同类型干酪根热解特性及微观机理分子动力学模拟OA

The in situ gasification of coal and the in situ modification of oil shale require high-temperature heating to decompose heavy components into light gaseous products,significantly enhancing the resource recovery efficiency of coal and oil shale.These processes represent key technologies in the current domain of in situ extraction of subsurface minerals.As the primary organic constituent in coal and oil shale,the pyrolysis behavior of kerogen is a critical determinant of the underground gasification potential of these resources.However,variations in pyrolysis characteristics and its microscopic mechanisms among different types of kerogen remain inadequately understood.In this study,we focus on kerogen types ⅠA,ⅡA,and ⅢA,extracting representative chemical structure fragments and employing quantum chemical methods to analyze the active sites in kerogen structural units during pyrolysis.Molecular dynamics simulations of the pyrolysis process under increasing temperatures were conducted with the ReaxFF reactive force field.The results demonstrate that carbonyl and carboxyl groups significantly weaken C-C bonds in kerogen.The kerogen pyrolysis process can be divided into three stages:the cleavage of weak chemical bonds forming large molecular components,the generation of abundant free radicals,and the recombination of free radicals with fragment products at elevated temperatures,which produce stable small molecules.These findings enhance theoretical understanding of the microscopic pyrolysis mechanisms of kerogen in coal and oil shale,providing critical theoretical support for advancing and innovating in situ mining technologies for underground coal and oil shale resources.