Research on the relationship between the structure and pyrolysis characteristics of pretreated Shendong coal.

• The content of phenolic hydroxyl increased during hydrothermal pretreatment. • OH-ether O hydrogen bonds were newly formed during THF swelling pretreatment. • Reactions during methane thermal pretreatment were bond breaking and re-bonding. • Structure-activity relationship between coal structure and pyrolysis was revealed. Studying the relationship between the structure and pyrolysis of coal is useful for understanding the coal pyrolysis mechanism. In this study, three typical pretreatment methods (viz. hydrothermal pretreatment, tetrahydrofuran swelling pretreatment, and methane thermal pretreatment) were selected to artificially change the structure and composition of Shendong coal. Subsequently, the physicochemical structure and pyrolysis characteristics of the pretreated coals were systematically investigated. The results indicate that the three pretreatment methods had different influences on the pore modification and evolution of the functional groups in coal, thereby destroying the cross-linking structure in different ways. Correspondingly, these changes eventually altered the distribution and composition of the pyrolysis products. Based on these findings, the different mechanisms underlying the pyrolysis behavior, involving alteration of the structure and composition, were analyzed, and the structure–activity relationship between the coal structure and the pyrolysis characteristics was explored. [ABSTRACT FROM AUTHOR]