I.FLUID CATALYTIC CRACKING: www.wissenschaftler-avh.in
B.CATALYST/ADDITIVES:
Q-46:
How Matrix and Zeolite Interact in Fluid Catalytic Cracking?
A-46
Interaction of Matrix and Zeolite in Catalytic Cracking
Modern fluid catalytic cracking (FCC) catalysts are composed of crystalline zeolite Y which is surrounded and held together by an amorphous silica/alumina matrix. Matrix contributes significantly to the overall performance of FCC catalysts. The catalyst matrix can be tailored to provide refiners with desired product quality and quantity. Therefore, in selecting FCC catalysts refiners should understand the type of matrix they need for their particular application.
Synergy of Matrix and Zeolite Increases Conversion
The mechanism of primary matrix cracking of hydrocarbons followed by secondary zeolite cracking can be better understood when the zeolite pore size is considered. The zeolite pore size is not suitable for cracking large hydrocarbon molecules since the pores are too small (< 8 Angstroms in diameter) to allow them to diffuse to the cracking sites. The zeolite catalyst in this experiment, for example, can convert only about half of the feed to products having a boiling point below 421°F (216°C). With the addition of the amorphous catalyst which contains larger pores ( >50 Angstroms) however, many additional molecules can be cracked on the more accessible matrix cracking sites. Relatively few of the products of matrix cracking are in the gasoline boiling range or lighter, so by the above definition, the amorphous catalyst provides minimal "conversion". The amorphous catalyst does, however, produce a wide range of intermediate, partially cracked products whose boiling points exceed 421°F (216°C ). These intermediate products, when added to the lighter feed molecules that are already of a size allowing diffusion into the zeolite, significantly increase the fraction of hydrocarbon molecules which are available for zeolite cracking. The result is a synergistic interaction between matrix and zeolite in which the activity attained by their combined effects is far greater than the sum of their individual effects.
FCC catalyst matrix plays a key role in determining overall activity, selectivity, and octane trends. Matrix provides primary cracking sites, generating intermediate feed molecules for further cracking to desirable products by the internal zeolite sites. The type of matrix used in the cracking catalyst alters activity and selectivities and can be controlled by the manufacturer to meet specific refining needs.
B.CATALYST/ADDITIVES:
Q-46:
How Matrix and Zeolite Interact in Fluid Catalytic Cracking?
A-46
Interaction of Matrix and Zeolite in Catalytic Cracking
Modern fluid catalytic cracking (FCC) catalysts are composed of crystalline zeolite Y which is surrounded and held together by an amorphous silica/alumina matrix. Matrix contributes significantly to the overall performance of FCC catalysts. The catalyst matrix can be tailored to provide refiners with desired product quality and quantity. Therefore, in selecting FCC catalysts refiners should understand the type of matrix they need for their particular application.
Synergy of Matrix and Zeolite Increases Conversion
The mechanism of primary matrix cracking of hydrocarbons followed by secondary zeolite cracking can be better understood when the zeolite pore size is considered. The zeolite pore size is not suitable for cracking large hydrocarbon molecules since the pores are too small (< 8 Angstroms in diameter) to allow them to diffuse to the cracking sites. The zeolite catalyst in this experiment, for example, can convert only about half of the feed to products having a boiling point below 421°F (216°C). With the addition of the amorphous catalyst which contains larger pores ( >50 Angstroms) however, many additional molecules can be cracked on the more accessible matrix cracking sites. Relatively few of the products of matrix cracking are in the gasoline boiling range or lighter, so by the above definition, the amorphous catalyst provides minimal "conversion". The amorphous catalyst does, however, produce a wide range of intermediate, partially cracked products whose boiling points exceed 421°F (216°C ). These intermediate products, when added to the lighter feed molecules that are already of a size allowing diffusion into the zeolite, significantly increase the fraction of hydrocarbon molecules which are available for zeolite cracking. The result is a synergistic interaction between matrix and zeolite in which the activity attained by their combined effects is far greater than the sum of their individual effects.
FCC catalyst matrix plays a key role in determining overall activity, selectivity, and octane trends. Matrix provides primary cracking sites, generating intermediate feed molecules for further cracking to desirable products by the internal zeolite sites. The type of matrix used in the cracking catalyst alters activity and selectivities and can be controlled by the manufacturer to meet specific refining needs.
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