3.2.2 Modification of Alkanes by Cracking Flashcards
1
Q
How can alkanes be made?
A
- Addition of H to alkenes
- Cracking longer alkane chains
2
Q
What is crude oil
A
Mixture of hydrocarbons containing alkanes, cycloalkanes and arenes
3
Q
Why is cracking done?
A
Smaller hydrocarbon compounds are more useful tan longer ones
4
Q
How is cracking done?
A
- Large hydrocarbons fed into steel chamber
- High temperatures
- Passed over Al2O3 catalyst
- No oxygen present to prevent combustion of hydrocarbons
5
Q
What are the types of cracking
A
Thermal Cracking : High temps and high pressure (up to 1000 degrees and 70 atmospheres) and produces mostly alkenes and some alkanes
Catalytic Cracking : Lower temperatures and slight pressure (450 degrees) and presence of zeolite or Al2O3 catalyst to produce mainly cyclic alkanes and aromatic hydrocarbons
6
Q
Steam Cracking Conditions
A
- High temperatures (up to 1000 degrees celsius)
- High pressure (70 atm)
- Mostly alkenes and some alkanes
7
Q
Catalytic Cracking Conditions
A
- Lower temperatures (450 degrees)
- Zeolite or Al2O3 catalyst
- Mainly aromatic hydrocarbons
