2
such as naphtha, kerosene, diesel, VGO, and residue. Catalysts form the heart of the
process because all of the hydroprocessing reactions occur over the surface of the
catalyst. The field of hydroprocessing catalysis is continuously evolving due to the
growing demand for clean middle distillates and increasingly stringent specifications for automotive fuels such as gasoline and diesel. Also, lower demand for heavy
fuel oils has been driving the refining industry more toward residue hydroprocessing, and in recent times, catalytic hydroprocessing has taken center- stage among
residue upgradation processes. Researchers are continuously developing new-generation high-activity catalysts and novel process configurations to cater to the needs
of changing refining market demands and product quality requirements.
The performance of hydroprocessing operations, both hydrotreating and hydrocracking, depends largely on the following aspects for any given feedstock
characteristics:
• Type of reactor system.
• Type of the catalyst system.
• Process parameters.
For a particular type of reactor system, the type of catalyst can be tailored to meet
the requirements of specific product slate and product quality for a given feedstock.
Catalysts also play an important role in the selection of process parameters for a
particular hydroprocessing application.
Hydroprocessing catalysts that are widely employed in commercial applications
are metals of group VI A (Mo and W) with promoter metals of group VIII A (Co and
Ni) or noble metals (Pt and Pd) supported on a suitable support material. The common support materials include alumina, silica-alumina, and zeolites. The active
sites of the metal promote hydrogenation/dehydrogenation reactions, and the acid
sites of the support promote hydrocracking reactions. The catalyst should also possess good mechanical strength to withstand the severe process conditions such as
high pressure and high temperature employed during hydroprocessing along with
appropriate physical properties such as surface area, pore volume, pore diameter,
and pore size distribution for better activity and molecular diffusion.
Feedstock properties have a significant effect on the performance of hydroprocessing catalysts and thus play an essential role during the design of hydroprocessing catalysts for a particular service. Parameters such as the concentration of
heteroatoms (mostly sulfur and nitrogen) and molecular weight distribution of the
feedstock need to be considered for the design of distillate hydroprocessing catalysts, while the concentration of metals and asphaltenes are the major factors in the
case of catalyst design for heavy oil hydroprocessing. Several factors need to be
considered while designing a catalyst for a particular hydroprocessing application
such as the type of active metals, choice of support, promoters, mechanical and
physical properties, feedstock characteristics, extent of conversion, required product slate, etc. Since catalyst design is of paramount importance for the success of
hydroprocessing applications, it is essential to delve into the advances in the area of
hydroprocessing catalysis and the factors influencing the performance and operation of these catalysts. The present chapter focuses mainly on the catalytic
G. Valavarasu and B. Ramachandrarao
such as naphtha, kerosene, diesel, VGO, and residue. Catalysts form the heart of the
process because all of the hydroprocessing reactions occur over the surface of the
catalyst. The field of hydroprocessing catalysis is continuously evolving due to the
growing demand for clean middle distillates and increasingly stringent specifications for automotive fuels such as gasoline and diesel. Also, lower demand for heavy
fuel oils has been driving the refining industry more toward residue hydroprocessing, and in recent times, catalytic hydroprocessing has taken center- stage among
residue upgradation processes. Researchers are continuously developing new-generation high-activity catalysts and novel process configurations to cater to the needs
of changing refining market demands and product quality requirements.
The performance of hydroprocessing operations, both hydrotreating and hydrocracking, depends largely on the following aspects for any given feedstock
characteristics:
• Type of reactor system.
• Type of the catalyst system.
• Process parameters.
For a particular type of reactor system, the type of catalyst can be tailored to meet
the requirements of specific product slate and product quality for a given feedstock.
Catalysts also play an important role in the selection of process parameters for a
particular hydroprocessing application.
Hydroprocessing catalysts that are widely employed in commercial applications
are metals of group VI A (Mo and W) with promoter metals of group VIII A (Co and
Ni) or noble metals (Pt and Pd) supported on a suitable support material. The common support materials include alumina, silica-alumina, and zeolites. The active
sites of the metal promote hydrogenation/dehydrogenation reactions, and the acid
sites of the support promote hydrocracking reactions. The catalyst should also possess good mechanical strength to withstand the severe process conditions such as
high pressure and high temperature employed during hydroprocessing along with
appropriate physical properties such as surface area, pore volume, pore diameter,
and pore size distribution for better activity and molecular diffusion.
Feedstock properties have a significant effect on the performance of hydroprocessing catalysts and thus play an essential role during the design of hydroprocessing catalysts for a particular service. Parameters such as the concentration of
heteroatoms (mostly sulfur and nitrogen) and molecular weight distribution of the
feedstock need to be considered for the design of distillate hydroprocessing catalysts, while the concentration of metals and asphaltenes are the major factors in the
case of catalyst design for heavy oil hydroprocessing. Several factors need to be
considered while designing a catalyst for a particular hydroprocessing application
such as the type of active metals, choice of support, promoters, mechanical and
physical properties, feedstock characteristics, extent of conversion, required product slate, etc. Since catalyst design is of paramount importance for the success of
hydroprocessing applications, it is essential to delve into the advances in the area of
hydroprocessing catalysis and the factors influencing the performance and operation of these catalysts. The present chapter focuses mainly on the catalytic
G. Valavarasu and B. Ramachandrarao