Reaction Behaviors of Polycyclic Aromatic Hydrocarbon Moleculesin a Diesel Hydro-Upgrading Process Based on the Molecular-LevelReaction Kinetic Model

A molecular-level reaction kinetic model for the diesel hydro-upgrading (DHU) process was established on the basisof the structure-oriented lumping (SOL) method to describe the hydro-upgrading reaction network and investigate the reactionbehaviors of polycyclic aromatic hydrocarbon (PAH) molecules. Twenty-two structural increments were selected to construct an835 rowx23 column feed oil molecular matrix based on the composition analysis. Twenty-eight reaction rules were formulated todeduce molecular reactions according to the hydro-upgrading reaction mechanism. One-hundred ninety-seven structural vectorswere used to represent the PAH molecules and 299 structural vectors were used to represent the monocyclic aromatic hydrocarbon(MAH) molecules. The reaction network containing about 24 600 reactions was generated and calculated byMATLABprogramming. The reliability of the model was verified by industrial data. The molecular matrix transformation could clearly trackthe reaction path of the petroleum molecules and reveal the influence of the temperature and the hydrogen partial pressure on PAHmolecules in the reaction network. The hydro-upgrading process containing the reactions of aromatic hydrogenation and ringopening reduced the PAH content and increased the cetane number (CN). At a hydrogen partial pressure of 10.0 MPa, the optimalreactor operating temperature range was 304.1-324.1 degrees C when the diesel yield was required to be larger than 88.0 wt % and thePAH content was less than 5.5 wt % in the refinery.

Automated summary

A molecular-level reaction kinetic model for the diesel hydro-upgrading process was established, which revealed the reaction behaviors and factors influencing the reactions. The study showed that the hydro-upgrading process could reduce PAH content and increase diesel yield under specific conditions.