Relative cracking rates: in catalytic cracking versus thermal cracking, olefins are observed to crack how many times faster under catalytic conditions?

Introduction:
Catalytic cracking leverages acidic catalysts to accelerate carbon–carbon bond scission, especially in olefins, compared with purely thermal mechanisms. Understanding order-of-magnitude rate differences explains why FCC units are so effective at converting heavy feeds to lighter products.

Given Data / Assumptions:

• Comparison: catalytic vs thermal cracking rates for olefins.
• Looking for an order-of-magnitude range rather than an exact number.

Concept / Approach:
Acidic zeolite catalysts stabilize carbocation intermediates, dramatically increasing reaction rates for olefin cracking. Literature commonly cites differences on the order of three to four magnitudes for olefinic species under catalytic conditions versus thermal alone.

Step-by-Step Solution:
Catalyst presence → carbocation pathway → much higher rates.Typical multiplier → 10^3 to 10^4 faster for olefins.Choose range 1000–10000 as the best answer.

Verification / Alternative check:
FCC fundamentals texts emphasize very large rate enhancements for olefin reactions on acidic catalysts relative to thermal cracking benchmarks.

Why Other Options Are Wrong:
10, 100, 200–300: Understate the magnitude of catalytic acceleration for olefins.About the same: Contradicts catalytic mechanism benefits.

Common Pitfalls:
Assuming similar rate enhancements for all hydrocarbon classes; olefins are especially reactive in catalytic environments.

Final Answer:
1000–10000