Cracking + reforming Flashcards
What is cracking?
Breaking long chain hydrocarbons into smaller hydrocarbons by breaking C-C bonds
Why is cracking done?
Because light fractions of hydrocarbons are higher in demand thus more valuable than heavier fractions
So heavier fractions broken down into lighter
2 types of cracking
Catalytic
Thermal
Thermal cracking
Using high heat and pressure to break C-C bonds in long chain hydrocarbons
What does thermal cracking produce a lot of?
Alkenes
Why is thermal cracking done?
To produce alkenes which act as the monomer for polymers, other useful products
Thermal cracking conditions
1000°c
70atm
Catalytic cracking
Using a catalyst so to break the C-C bond we don’t have to raise the temperature as high
Which will cut costs by saving time and money to heat at high temps
What does catalytic cracking produce a lot of?
Aromatic compounds (cycloalkanes) which have a benzene ring
What is the catalyst used in catalytic cracking?
Zeolite (hydrated aluminosilicate)
Catalytic cracking conditions
Zeolite/ hydrated aluminosilicate catalyst
450°c
Slight pressure
Reforming
Process of converting straight chain alkanes into branched or cycloalkanes for more efficient combustion when used as fuel
Why is reforming done?
Because using straight chain hydrocarbons such as diesel or petrol for fuel can cause knocking in cars, which isn’t wanted. So we avoid this by reforming so not linear
What is knocking?
When a hydrocarbon such as petrol in a car’s fuel explodes on its own accord when compressed
What catalyst is used in reforming?
Platinum on aluminium oxide
Abbreviated as Pt
