Radical-induced pyrolysis mechanism in Cal–O and Cal–Cal bond cleavage

During direct coal liquefaction , selective C al –O bond cleavage is critical for phenol production. In this study, anisole and benzyl phenyl ether were chosen as the oxygen-containing model compounds. Radical-induced sites of benzyl phenyl ether were investigated using the Fukui function and energy barrier calculation. The promotion routes of the C al –O bond cleavage in anisole and benzyl phenyl ether by radicals were illustrated. The formation of o -benzyl phenol was regarded as a sign of benzyl radical-induced pyrolysis based on the most optimal path. The competitive process between the optimal path and β-bond scission path was analyzed from the rate constant perspective. Radical-induced pyrolysis made remarkable differences in product selectivity for benzyl phenyl ether. Similarly, the cleavage of the C al –C al bond can also be promoted using two methods of radical induction, which is referred to as a radical chain process. In contrast to benzyl phenyl ethers, the induced pyrolysis of the C al –C al bond in bibenzyl is more likely to occur via β-bond scission after the H of CH 2 is abstracted by a radical. The findings of this research would provide a theoretical foundation for comprehending the radical mechanism of direct coal liquefaction.