In the present work, studies were carried out with the objective of utilizing spent residue hydroprocessing
catalysts, which contained coke and metal (V and Ni) deposits, in the preparation of active new catalysts that
can be used for hydrodemetallization of residual oils. Three types of spent catalysts that contained different
levels of vanadium, molybdenum, and nickel were used in the experiments. These catalysts were collected
from different reactors (front, middle, and back-end) of an industrial atmospheric residue desulfurization
unit. A series of catalysts were prepared by mixing and kneading of spent catalysts with boehmite in different
proportions followed by extrusion of the resulting paste. All prepared catalysts were characterized by chemical
analysis and by surface area, pore volume, and pore size measurements, and their hydrodesulfurization (HDS)
and hydrodemetallization (HDM) activities were evaluated by hydrotreating tests in a fixed-bed reactor using
Kuwait atmospheric residue as feed. A commercial HDM catalyst was also tested under the same operating
conditions and its HDM and HDS activities were compared with that of the prepared catalysts. The results
revealed that the catalysts prepared from spent catalyst/boehmite blends contained vanadium, molybdenum,
and nickel. The relative concentrations of these metals (V, Mo and Ni) in the prepared catalysts and other
key properties such as surface area, porosity, and crushing strength showed a strong dependence on the amount
and the type of spent catalyst used in the preparation. Forty to 60 wt % of spent catalysts could be mixed
with boehmite and extruded to produce active HDM catalysts. Catalysts prepared from the spent catalysts
with low vanadium content such as those discarded from the back-end reactors of an atmospheric residue
desulfurization unit were more active than a reference commercial HDM catalyst for promoting HDM and
HDS reactions. The presence of some kind of new active sites involving a combination of the three metals
Mo, Ni, and V together with the reasonably high surface area and porosity could be responsible for the high
hydrotreating activity of the catalyst prepared by mixing spent catalyst with boehmite.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.