In the industrial refining of crude oil, catalytic cracking is widely used to convert long-chain heavy gas oil fractions into gasoline and light alkenes. Which of the following best describes the primary advantage of employing a zeolite catalyst in this process compared to thermal cracking?
- It allows cracking to proceed at lower temperatures and pressures while yielding a higher proportion of branched-chain hydrocarbonsAnswer
- BIt shifts the chemical equilibrium to ensure total conversion of gas oil into straight-chain alkanes without producing alkenes
- CIt increases the boiling points of the heavy gas oil molecules so that they condense faster in the fractionating column
- DIt functions as a consumable limiting reactant that determines the maximum mole yield of gasoline produced
Answer
The primary advantage of catalytic cracking is that it reduces energy requirements by operating at lower temperatures and pressures while producing a higher yield of high-octane branched-chain hydrocarbons.
In industrial petroleum refining, catalytic cracking uses zeolites (aluminosilicate catalysts) to accelerate hydrocarbon breakdown at moderate temperatures (~500 °C) and relatively low pressures. In addition to reducing energy demands, zeolites selectively encourage the formation of branched-chain alkanes and aromatics, which greatly improves the octane rating of the resulting petrol.
Step-by-Step Solution
Key Concept
Industrial Petroleum Refining and Catalytic Cracking