5.14 describe how lng-chain alkanes are converted to alkenes and shorter-chaiin alkanes by catalytic cracking, using silica or alumina as the atalyst and a temperature in the range of 600-700°C

If carrying out the reaction in a lab...
1- Heat the hydrocarbon (e.g. paraffin).
2- After a few seconds, move the Bunsen burner to heat the silica/aluminium catalyst
3- Alternate between the two until the paraffin vaporises and the catalyst glows red
4- The heated paraffin vapour cracks as it passes over the heated catalyst
5- small alkanes collect at the end of the boiling tube, while alkene gases travel down the delivery tube
6- The alkenes are collected through water using a glass jar


In industry, vapourised hydrocarbons are passed over a powdered catalyst at about 600-700°C. silica and aluminium are used as catalysts.

Notes credit: CGP