First-Principles-Based\nSimulation of the Product Yields\nObtained in an Industrial Vacuum Gas Oil Hydroconversion Unit

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