The catalyst’s activity is measured by a standard laboratory (MAT) test. The
base catalyst without zeolite can have an activity as low as four MAT though
numbers ranging from 20 to 45 MAT are more typical. Commercial FCC operations
have activities that range from 58 to 77 MAT with 62–72 being the most common
range.
The matrix is the rest of the catalyst and contains clay, additives, and/or a binder
that holds all the components together. Important properties such as the catalyst’s
attrition characteristics, density, CO burning rate, coke selectivity, bottom cracking,
and dry gas make are a direct function of the matrix composition.
Clay is used as filler and provides some pore structure. Additives such as
alumina and silica-alumina are used to increase the matrix cracking activity and
crack large molecules. Binders can consist of silica, alumina, or silica-alumina and
can also enhance activity. In the new catalysts, more than one additive can be
incorporated into the catalyst and small amounts of secondary compounds such as
titanium or phosphorus can modify the catalyst’s performance.
The ratio of zeolite to matrix is used to vary the yields from an FCC and must be
optimized for each matrix and zeolite system. Each feedstock with different
properties such as molecular weight and aromaticity requires a unique catalyst
formulation. Figure 28a–c shows how the ratio of zeolite to matrix affects yields for
a 22.5
API (11.5 K) feed.
In addition to FCC catalysts, there is now a long list of FCC additives to meet
specific processing needs. These include products for:
• SO x removal
• NO x removal
• Octane enhancement
• Metal passivation
• Bottom cracking
• Fluidization aids
• Olefin generation
A compilation of all the commercially available products is given in Appendix 1.
Cracking for Light Olefins and Aromatics (Petrochemicals)
The demand for propylene as a petrochemical feedstock is outpacing the need for
ethylene. As a result, the traditional source of propylene, i.e., as by-product of the
steam cracker, is not sufficient for future propylene projections.
Catalytic cracking is the other major source of propylene with the balance being
propane dehydrogenation, metathesis, olefin cracking, and MeOH to propylene.
Worldwide market shares (2010) are 52:36:12, though catalytic cracking has
overtaken steam cracking in the United States as the largest single source of
propylene used for petrochemicals. The fracking technology has made large
amounts of ethane and propane available to the US market. The ethane is replacing
Fluid Catalytic Cracking (FCC) in Petroleum Refining
297
base catalyst without zeolite can have an activity as low as four MAT though
numbers ranging from 20 to 45 MAT are more typical. Commercial FCC operations
have activities that range from 58 to 77 MAT with 62–72 being the most common
range.
The matrix is the rest of the catalyst and contains clay, additives, and/or a binder
that holds all the components together. Important properties such as the catalyst’s
attrition characteristics, density, CO burning rate, coke selectivity, bottom cracking,
and dry gas make are a direct function of the matrix composition.
Clay is used as filler and provides some pore structure. Additives such as
alumina and silica-alumina are used to increase the matrix cracking activity and
crack large molecules. Binders can consist of silica, alumina, or silica-alumina and
can also enhance activity. In the new catalysts, more than one additive can be
incorporated into the catalyst and small amounts of secondary compounds such as
titanium or phosphorus can modify the catalyst’s performance.
The ratio of zeolite to matrix is used to vary the yields from an FCC and must be
optimized for each matrix and zeolite system. Each feedstock with different
properties such as molecular weight and aromaticity requires a unique catalyst
formulation. Figure 28a–c shows how the ratio of zeolite to matrix affects yields for
a 22.5
API (11.5 K) feed.
In addition to FCC catalysts, there is now a long list of FCC additives to meet
specific processing needs. These include products for:
• SO x removal
• NO x removal
• Octane enhancement
• Metal passivation
• Bottom cracking
• Fluidization aids
• Olefin generation
A compilation of all the commercially available products is given in Appendix 1.
Cracking for Light Olefins and Aromatics (Petrochemicals)
The demand for propylene as a petrochemical feedstock is outpacing the need for
ethylene. As a result, the traditional source of propylene, i.e., as by-product of the
steam cracker, is not sufficient for future propylene projections.
Catalytic cracking is the other major source of propylene with the balance being
propane dehydrogenation, metathesis, olefin cracking, and MeOH to propylene.
Worldwide market shares (2010) are 52:36:12, though catalytic cracking has
overtaken steam cracking in the United States as the largest single source of
propylene used for petrochemicals. The fracking technology has made large
amounts of ethane and propane available to the US market. The ethane is replacing
Fluid Catalytic Cracking (FCC) in Petroleum Refining
297