8
• Is easy to form into desired shapes.
• Is relatively cheap.
Recently, other supports such as mixed oxides and zeolites have also been
reported for hydrotreating applications. HDT catalysts usually do not require highly
acidic supports in order to suppress the cracking activity and increase product yields
unlike hydrocracking catalysts. The surface area of the support material is normally
in the range of 100–350 m
2
/g. The structure of the support plays an important role
in influencing the catalytic activity. Commonly used hydrotreating catalyst support
such as γ-alumina with similar chemical composition but varied structure was found
to exhibit different conversions during cracking of n-heptane due to the differences
in the support structure [5].
4.3 Acidity
Acidity is provided by acid sites present in the hydrotreating catalyst support. The
proper balance of acid strength and acid site distribution is essential for optimum
activity and selectivity of HDT catalysts. Acidity does not play a major role in HDT/
HDS catalysts since most of the reactions occur over metallic sites and acidic activity is not much desirable due to the formation of lighter ends and resultant loss of
valuable product yield due to hydrocracking reaction. In contrast, support acidity
plays a crucial role in the case of hydrocracking catalysts to impart the cracking
activity and product conversion. Weak acidity with strong hydrogenation activity is
the primary requirement for any hydrotreating catalyst.
4.4 Textural Properties
Textural properties of hydrotreating catalysts such as geometric structure and morphology from the macro- to the microlevel influence the performance of HDT catalysts in a significant manner. These textural properties are listed in Table 3.
Microlevel catalyst properties such as pore size and pore size distribution greatly
influence the hydrotreating activity. HDT catalysts have different mesopore/
Table 3 Textural properties of hydrotreating catalysts
Textural properties
Macrolevel properties
Microlevel properties
Size of the catalyst particle
Surface area
Shape of the catalyst particle (e.g., pellets, rings,
extrudates, lobes)
Pore structure
Pore size
Pore size distribution
G. Valavarasu and B. Ramachandrarao
• Is easy to form into desired shapes.
• Is relatively cheap.
Recently, other supports such as mixed oxides and zeolites have also been
reported for hydrotreating applications. HDT catalysts usually do not require highly
acidic supports in order to suppress the cracking activity and increase product yields
unlike hydrocracking catalysts. The surface area of the support material is normally
in the range of 100–350 m
2
/g. The structure of the support plays an important role
in influencing the catalytic activity. Commonly used hydrotreating catalyst support
such as γ-alumina with similar chemical composition but varied structure was found
to exhibit different conversions during cracking of n-heptane due to the differences
in the support structure [5].
4.3 Acidity
Acidity is provided by acid sites present in the hydrotreating catalyst support. The
proper balance of acid strength and acid site distribution is essential for optimum
activity and selectivity of HDT catalysts. Acidity does not play a major role in HDT/
HDS catalysts since most of the reactions occur over metallic sites and acidic activity is not much desirable due to the formation of lighter ends and resultant loss of
valuable product yield due to hydrocracking reaction. In contrast, support acidity
plays a crucial role in the case of hydrocracking catalysts to impart the cracking
activity and product conversion. Weak acidity with strong hydrogenation activity is
the primary requirement for any hydrotreating catalyst.
4.4 Textural Properties
Textural properties of hydrotreating catalysts such as geometric structure and morphology from the macro- to the microlevel influence the performance of HDT catalysts in a significant manner. These textural properties are listed in Table 3.
Microlevel catalyst properties such as pore size and pore size distribution greatly
influence the hydrotreating activity. HDT catalysts have different mesopore/
Table 3 Textural properties of hydrotreating catalysts
Textural properties
Macrolevel properties
Microlevel properties
Size of the catalyst particle
Surface area
Shape of the catalyst particle (e.g., pellets, rings,
extrudates, lobes)
Pore structure
Pore size
Pore size distribution
G. Valavarasu and B. Ramachandrarao