Temperature

Steam cracking reactions are highly endothermic. Increasing temperature favors the formation of olefins, high molecular weight olefins, and aromatics. Optimum temperatures are usually selected to maximize olefin production and minimize formation of carbon deposits. Reactor temperature is also a function of the feedstock used. Higher molecular weight hydrocarbons generally crack at lower temperatures than lower molecular weight compounds. For example, a typical furnace outlet temperature for cracking ethane is approximately 800°C, while the temperature for cracking naphtha or gas oil is about 675–700°C.