First-Principles-Based Simulation of the Product Yields Obtained in an Industrial Vacuum Gas Oil Hydroconversion Unit

The product yields obtained in an industrial vacuum gas oil (VGO) hydroconversion unit were assessed using PR1ME, i.e., an innovative first-principles-based simulation framework. This required coupling of an enhanced single-event microkinetics (SEMK) model with a Shannon-based molecular reconstruction method. It allowed to describe the feed at a molecular level from the measured bulk properties. The catalyst descriptors, such as acid strength and concentration of active sites, in the kinetic model were fine-tuned, next to the physisorption enthalpy within the catalyst pores for feed and product species to accurately model the process performance in different operational windows, i.e., Start-Of-Run (SOR), Mid-Of-Run (MOR), and End-Of-Run (EOR). Reducing the physisorption strength, corresponding to less negative values of the standard heats of adsorption, sufficed to capture the differences in conversion and selectivities between SOR and MOR. These differences indicate weaker interactions between the molecules and the catalyst surface, which is attributed to reduced accessibility to catalyst pores due to coking. Particularly between the MOR and EOR windows, an additional adjustment in protonation enthalpy (+4 kJ/mol) was necessary, indicating that carbon deposition not only affects the adsorption capacity of the catalyst but also reduces the strength of the acid sites.