Where does the CO2 come from when styrene monomer is made?

Most styrene is made by dehydrogenating ethylbenzene with superheated steam, so the main source is fuel burned in the steam superheater and boilers. Off-gas burned as fuel adds to it. Count fuel CO2 in Scope 1 and purchased benzene and ethylene in Scope 3.

Scope 1 sources

• Fuel for the steam superheater, the largest single use.
• Hydrogen-rich off-gas burned as fuel.
• Flaring during start up and upsets.

Scope 3 sources

• Benzene and ethylene, or bought ethylbenzene.
• Catalyst and chemicals.
• Transport of feedstock.

Co-products

Toluene and off-gas leave the unit alongside styrene. If you split emissions between them, write down the method and use it every year.

What Senseible does here

Senseible reads bills, fuel invoices and production records into dated, fingerprinted records, so the figure you send a buyer can be traced to its documents.

• Steam cracker CO2
• Polymer resin factors
• Epoxy resin footprint

Sources: IPCC 2006 Guidelines, Volume 2 Energy (fuel defaults), GHG Protocol Corporate Standard, GHG Protocol Corporate Value Chain (Scope 3) Standard

Last reviewed 2026-10-22.