What is the primary purpose of Fluid Catalytic Cracking (FCC) in petroleum refining?
A
To distill crude oil into different fractions
B
To convert heavy hydrocarbons into lighter, more valuable products like gasoline
C
To remove sulfur from diesel
Analysis & Theory
FCC is used to break down large hydrocarbon molecules into lighter products such as gasoline and olefins.
What type of catalyst is commonly used in FCC units?
B
Zeolite-based catalysts
Analysis & Theory
Zeolite-based catalysts are widely used in FCC for their high activity and selectivity in cracking reactions.
FCC operates under which of the following conditions?
A
Low temperature and high pressure
B
Moderate temperature and atmospheric pressure
C
High temperature and low pressure
D
High pressure and low temperature
Analysis & Theory
FCC typically operates at high temperatures (470–520°C) and relatively low pressure (1.5–3 atm).
Which of the following is a major product of FCC?
Analysis & Theory
FCC primarily produces high-octane gasoline, along with LPG and light olefins.
Why is the catalyst continuously regenerated in FCC?
A
To maintain high pressure
B
To burn off deposited coke and restore activity
Analysis & Theory
Coke deposits on the catalyst during cracking; regeneration burns it off to restore catalyst activity.
Which of the following feeds is typically used in FCC units?
Analysis & Theory
FCC units primarily process Vacuum Gas Oil (VGO), a heavy distillate from vacuum distillation.
What is the role of the riser in FCC?
B
To store cracked products
C
To mix feed and catalyst and allow cracking reactions
D
To burn sulfur compounds
Analysis & Theory
The riser is where hot catalyst and feed are mixed, and cracking reactions occur rapidly in seconds.
What happens to the catalyst after cracking in the FCC riser?
B
It is cooled and reused without regeneration
C
It is regenerated by burning off coke
D
It is dissolved in gasoline
Analysis & Theory
Catalyst is sent to the regenerator where coke is burned off before being reused.
Which of the following is a by-product of FCC catalyst regeneration?
Analysis & Theory
During regeneration, coke on the catalyst is combusted, producing CO₂ (and sometimes CO).
What is the main advantage of FCC in modern refineries?
A
It reduces sulfur in fuels
B
It converts light gases into asphalt
C
It increases gasoline and olefin yield from heavy fractions
D
It eliminates the need for distillation
Analysis & Theory
FCC enhances the value of heavy fractions by converting them into high-demand lighter fuels and petrochemical feedstocks.