Cracking and Reforming Flashcards
which fractions of hydrocarbons are most in demand?
fractions with shorter C chains
how is demand for shorter C chain fractions met?
longer hydrocarbons are cracked - breaking long-chain alkanes into smaller hydrocarbons, involves breaking C-C bonds
Give 2 conditions of thermal cracking
- 900°C - high temperature
- Up to 70 atm - high pressure
What does thermal cracking produce?
high proportion of alkanes and alkenes
Name 3 conditions of catalytic cracking
- Uses zeolite catalyst
- normal pressure
- 450°C - lower temperatures
why is a zeolite catalyst used in catalytic cracking?
needed to compensate for less harsh conditions (lower pressure and temperature)
also speeds up reactions, saving time and money
What does catalytic cracking normally produce?
aromatic hydrocarbons with carbon rings
Why doesn’t cracking produce 2 alkanes?
Since there isn’t enough hydrogen atoms to produce 2 alkanes = one of new chains has C=C
How are the products obtained from cracking separated?
fractional distillation
what is reforming?
straight chain hydrocarbons converted to branched chain alkanes and cyclic alkanes
why are hydrocarbons reformed?
to burn more efficiently and used in petrol for cars
