Download - Egyptian Petroleum Research Institute

3- PETROCHEMICALS
Edited by: Vivek Patel
Published by: InTech,
Croatia, March 2012.
ISBN: 978-953-51-0411-7
www.intechopen.com
Chapter 12 – New Trends
in Hydroprocessing Spent
Catalysts Utilization
249
Hoda S. Ahmed and
Mohammed F. Menoufy
Summary of the chapter:
The objective of this
chapter is to give academics, research scientists, research
scholars, science and engineering students and industry
professionals an overview of the different utilization technologies
for hydrotreating spent catalysts.
Hydrotreating catalysts consist of critical metals such as Mo, Co,
and Ni, as active metals and are generally supported by alumina
or silica alumina and are usually used in hydrotreating
petroleums. These catalysts deactivate with time, and partial or
complete regeneration can be carried out depending on the
severity of the processes due to carbon or sulfides deposition. In
the long term, the regeneration of these catalysts will become
impossible due to irreversible deactivation, and spent catalysts
would discard as solid wastes. The volume of these solid wastes
has increased significantly worldwide and in Egyptian petroleum
refining industries due to a steady increase in upgrading of
feedstock or distillates to meet the environmental regulations for
low sulfur fuels.
Several alternative methods such as disposal in landfills,
reclamation of metals, regeneration/ rejuvenation and reuse, and
utilization as raw materials to produce other useful products are
available to the refiners to deal with the spent catalyst problems.
The choice between these options depends on technical
feasibility and economic consideration.
In recent years, increasing emphasis has been placed on the
development of processes for recycling and recovering of the
waste catalyst metals, as much as possible. In literature there are
many applied researches for spent metals recovery, particularly
for catalyst that contain high concentrations of valuable metals
(Mo, Ni, V and Al2O3) However, fluctuations in the market prices
of the recovered metals and their purity, together with the high
costs of shipping significantly influence the economics of the
metal reclamation process that making it less attractive.
and metal contaminants. Therefore, many efforts were subjected
to replace the conventional regeneration procedures in order to
reactivate and rejuvenate the spent catalysts. The new
procedures are conducted to remove contaminant metals
selectively by chemical treatments without significantly affecting
the chemical and physical characteristics of the original catalyst
In experimental works, carried out by the authors of this
chapter in EPRI (1), concerning spent catalysts, were succeeded
in rejuvenating the spent catalyst Mo-Ni/Al2O3 using for rerefining
of waste lube oil, and applied in Alexandria Petroleum
Company. Our data revealed that the treated spent catalyst could
be restored nearly its fresh HDS activity levels by application of
oxalic acid leaching technique in addition to H2O2 as an oxidizing
agent. The most effective leaching agent was 4% oxidized oxalic
acid, and the extent of metals recovered was dependent on acid
concentrations or the specific reuse of the spent catalyst. The
rejuvenation process promotes the formation of a
hydroprocessing catalyst due to its improvements in surface area
and average pore diameter (i.e. 87% and 63% of the fresh
catalyst characteristics, respectively). These improvements
caused recovery in the HDS activity of the treated catalyst in the
ranges of 81–96 wt %
Other utilization of spent catalysts, experimental data reveal
that the treatment processes succeeded for extracting nickel,
molybdenum and aluminum oxides in quantities of 25, 30, 45
wt% as raw materials using in the production of other valuable
industrial products. These results are attractive options from
environmental and economical points of view.
References of authors’ data:
1- E. Z. Hegazy., M.Sc. Thesis, Tanta University, Tanta (2003)
2- M. F. Menoufy, H. S. Ahmed, in Proc. of the OAPEC Seminar on
Energy Conservation and Environmental Protection in
Petroleum Industries, Cairo (2004).
3- M. F. Menoufy, H. S. Ahmed, .Energy Sources, Part A, 30:1213–
1222, (2008)
4- H S. Ahmed, M.F. Menoufy., Chem. Eng Technol., 32, No. 6,
873–880, (2009).
Many literature review revealed that reactivation of spent
catalysts technology did not reach to well developments.
Spent catalysts lose their activities, and deactivated by pore
blockage and fouling of the active surface with deposition of coke
EPRI Annual Report 2012 24