Model-feedstock studies on the hydrogenating, desulfurizing and denitrogenating activity of a fresh, spent and regenerated catalyst from ebullated-bed VRU

PETR 82

Robert Wandas, robert.wandas@obr.pl, Research & Development Center for the Refining Industry, ul. Chemikow 5, PL-09-411, Plock, Poland
A commercial NiMo/Al2O3 catalyst, used as ebullated-bed catalyst in a VRU (vacuum residue upgrading) unit in the Polish refining industry, has been tested in lab-scale experiments of hydrorefining of a model feedstock simulating to some extent the petroleum residue processed. Reaction networks in the process conducted in a trickle-bed reactor were determined for each reacting component of the model mixture, i.e. for 1-methylnaphthalene, quinoline and dibenzothiophene. Total conversion degrees as well as nitrogen and sulfur elimination degrees have been calculated for above components, in case of: fresh catalyst, spent catalyst from the VRU unit, the spent catalyst partly regenerated by supercritical extraction with a highly aromatic petroleum fraction and the spent catalyst regenerated by oxidative burn-off. Pseudo first-order rate constants for model reactions running were estimated. BET surface area and pore volume were measured for each catalyst sample. Supercritical extraction with the petroleum fraction practically does not restore the lost hydrogenating and denitrogenating activity of the spent VRU catalyst. It can be partially restored by oxidative burn-off of the coke deposited.