Coke formation typically occurs in two stages; an initial fast coking regime, and a later regime where the buildup of further coke is much slower, which indicates that early coking stages change catalysts selectivity to limit further coking. This change in selectivity has been attributed to carbon blocking the most reactive and least selective sites, which can catalyze side-reactions leading to coke formation. An additional explanation is that the presence of carbon can modify olefin adsorption strength on a surface, and increase the energy barrier for C-H activation. Coke may therefore deactivate Pt catalysts via an electronic interaction, in addition to steric blocking.