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Why does catalytic cracking produce more valuable products than thermal cracking?

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Aerial view of an oil refinery complex near New Orleans, Louisiana, with storage tanks, industrial structures, and smoke rising from the facility, surrounded by open land. — petroleum refining Aerial view of an oil refinery near New Orleans.

Catalytic cracking is more valuable than thermal cracking because it produces higher-quality products under less severe operating conditions, while significantly reducing the formation of low-value by-products like gas and coke.1

While thermal cracking relies on the free-radical theory—a process that often results in unstable naphthas and large amounts of coke—catalytic cracking utilizes the carbonium ion theory. By employing zeolitic and molecular sieve-based catalysts, refineries can achieve more selective yields of desired products.1

Key advantages of catalytic cracking include:
* Higher Octane Yields: It produces cracked naphtha with an octane number of 90 to 94, making it an essential gasoline blend stock.1
* Valuable Feedstocks: The process generates significant quantities of propylene and butylene, which serve as critical raw materials for polymerization and alkylation processes.1
* Efficiency: Modern fluid catalytic cracking allows for high conversion levels, often exceeding 80 percent in some facilities, by continuously regenerating the catalyst to maintain its activity.1