Hydrodesulfurization and hydrodemetallization of different origin vacuum residues: New modeling approach

In order to be able to upgrade the heaviest part of the crude oil one needs to remove several impurities, such as sulfur or metals. Residue hydrotreatment in fixed beds, under high hydrogen pressure can achieve high removal performances, with an industrial catalysts optimized staging. Despite the recent improvements, petroleum residues remain very difficult to describe and characterize in detail. Several kinetic models have been developed, but mostly they are feed dependant and their predictions are not satisfying for residues of different origins. Based on a recent study comparing residue properties and the differentiating physical-chemical properties responsible for reactivity (Ferreira et al., 2012), the present work develops a hydrotreatment kinetic model coupled with mass transfer in the catalyst which attempts to simulate the different residue performances. After estimation of kinetic parameters for a Iraqi residue (Buzurgan) with API gravity of 5, the model taking into account differences in residue characteristics, was validated for residues with API gravity close to Buzurgan one but shows increasing discrepancies with increasing API gravity.