Hydrocracking of Naphthalene by NiMo3S4/ZSM‐5 Catalyst: A Theoretical Study on the Reaction Mechanism

Abstract

The study for effective utilization and conversion of polycyclic aromatic hydrocarbons in heavy oil of petroleum is of great significance in the chemical industry. Although extensive experiments have been conducted on the relevant catalyst performance and reaction conditions in the practical hydrocracking process, the reaction mechanism remains unclear. Here, a first‐principles study is performed to address this long‐standing issue by taking a polycyclic aromatic naphthalene molecule as an example and choosing a typical NiMo3S4/ZSM‐5 bi‐functional catalyst for the hydrocracking reaction. By comparing the performance of various crystal planes, it is identified that the (001) plane of NiMo3S4 and the (010) plane of ZSM‐5 are the most effective crystal planes for the hydrogenation and cracking processes, respectively. Based on this catalytic structure, an optimal hydrogenation pathway from naphthalene to tetralin (1α → 4α → 2β → 3β) is first revealed with the third hydrogen‐addition stage as the rate‐determining step. Then, it is disclosed that the cracking reaction occurs in the form of isomerization and energetically more favorable ring‐opening mode, and the main products are determined to include toluene, ethylbenzene, benzene, ethane, and methane. These results would deepen our understanding of the hydrocracking of naphthalene to tetralin and other products, and further promote the research of reaction mechanisms and more efficient catalysts for the utilization of polycyclic aromatic hydrocarbons in heavy oil of petroleum.