DFT Insights into Competitive Adsorption and Reaction Mechanism of Benzothiophene and Naphthalene on Fe-Doped Ni ₂P Catalyst

The competitive adsorption and reaction mechanism of benzothiophene (BT) and naphthalene at the active sites on the Ni2P (001) surfaces were systematically explored using density function theory (DFT) calculations. In the competitive adsorption process under reaction conditions, BT was preferred to occupy the P-hollow site and Ni-top site, while naphthalene was preferentially adsorbed at the Ni-hollow site on the Ni(I) structure surface. Fe atom doped was beneficial to improve the adsorption ability of probe molecules, in which the Ni-top site exhibited the highest adsorption ability for BT during competitive adsorption. In addition, the dominant reaction pathway of BT was HYD with the preferential cleavage route of the aryl C4-S bond, and the naphthalene tended to form tetralin and further saturated products through hydrogenation on the Ni(I) structure surface. Notably, the energy barrier for the C-S bond scission of BT, which was the rate control step, was significantly reduced after Fe atom doped on the Ni(I) structure surface (1.34 eV vs 1.05 eV). Meanwhile, the energy barrier for the cycloalkyl C-C bond scission of tetralin was also obviously decreased on the Fe-Ni(I) structure surface (2.02 eV vs 1.65 eV). Overall, Fe atom doped on the Ni(I) structure surface was of great significance to further improve the activity and selectivity of BT and naphthalene hydrogenation reactions.