Steam cracking

It is the principal industrial method for producing the lighter alkenes (or commonly olefins), including ethene (or ethylene) and propene (or propylene).

The main differences between each of them concerns the catalyst employed, design of the reactor and strategies to achieve higher conversion rates.

Steam cracking is the core technology that supports the largest scale chemical processes, i.e. ethylene and propylene.

Most of the energy recovered from the cracked gas is used to make high pressure (1200 psig (8300 kPa)) steam.

Even though the thorough energy integration within a steam cracking plant, this process produces an unsurmountable amount of carbon dioxide.

[4] Resulting in a staggering amount of more than 300 million tonnes of carbon dioxide that is annually emitted into the atmosphere of which 70–90% is directly attributed to the combustion of fossil fuel.

In the last few decades, several advances in steam cracking technology have been implemented to increase its energy efficiency.

Steamcracker II at the BASF site in Ludwigshafen/Germany
Steam cracker process diagram
Gibbs free energy per carbon atom. This shows that at high temperature, hexane can split into ethane and ethylene ("Ethen"), and ethane can split into ethylene and hydrogen. But ethylene can decompose into methane and carbon if given too much time, and all the hydrocarbons can decompose into carbon and hydrogen.
Ludwigshafen steamcracker at night