A method for reducing CO2 emissions from steam cracking operations can include: introducing an oxygen-rich stream comprising oxygen and from 0 wt % to 15 wt % nitrogen to a vessel; introducing hydrocarbon combustion fuel to the vessel; combusting oxygen and hydrocarbon combustion fuel in the vessel to (1) produce a flue gas comprising carbon dioxide and water and (2) heat a cracking coil passing through the vessel; and performing a steam cracking reaction in the cracking coil passing through the vessel.