Modeling and simulation of hydrodemetallation and hydrodesulfurization processes with transient catalytic efficiency

Abstract

A model is presented for the description of the concentration behavior of organometallic and sulfurated compounds in hydrodemetallation and hydrodesulfurization catalytic processes, where catalyst effectiveness decreases with time. Due to the complexity of the mixture, an approach based on pseudocomponents was adopted. The system is modeled as an isothermal tubular reactor with axial dispersion, where the gas phase (hydrogen in excess) flows upward concurrently with the liquid phase (heavy oil) while the solid phase (catalyst) stays inside the reactor in an expanded (confined) bed regime. The catalyst particles are very small and are assumed to be uniformly distributed in the reactor. The heavy oil fractions contain organometallics and sulfurated compounds, from which the metals and sulfur are to be removed, the metals as deposits in the catalyst pores and the sulfur as gas products. Simulations were carried out where the concentration profile inside the reactor was calculated for several residence times

Modeling of Hydrodesulfurization Catalysts. I. Influence of Catalyst Pore Structures on the Rate of Demetallization

“…Although experimental procedures to quantitatively describe the deactivation processes are available, the modeling approach has also received some attention. ,− In the present work, a second-order reaction mechanism for HDS catalysts is considered in a model simulation. Models developed for the macro-, micro-, and random pore structures were used in the prediction of catalyst lifetime.…”