What catalyst is standard in fluidized bed catalytic cracking units?
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Answer: D. All A., B. and C.
Explanation
Catalytic cracking units historically and currently employ various acidic catalysts. Silica-alumina, silica-magnesia, and treated bentonite clays represent standard cracking catalysts. These acidic solid materials promote carbonium ion reactions necessary for hydrocarbon cracking. Fluidized catalytic cracking uses circulating fine catalyst powders suspended in hydrocarbon vapors. Silica-alumina was the dominant synthetic catalyst used for decades in petroleum refineries. Modern fluid catalytic units primarily utilize synthetic zeolite catalysts for superior activity.
Refineries rely on fluid catalytic cracking to convert heavy gas oils into valuable gasoline and olefins. Catalyst regeneration burns off coke deposits continuously to maintain high catalytic activity. Selecting the proper catalyst formulation maximizes gasoline yield while minimizing undesirable dry gas. Option A silica-magnesia was used historically as an active cracking catalyst formulation. Option B silica-alumina served as the foundational synthetic catalyst for early cracking units. Option C bentonite clays were among the earliest natural mineral catalysts utilized in refining.
- Subject
- Engineering
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- Chemical Engineering
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