The first step of the mechanism is the dissociative adsorption of O 2 onto the surface. Like other works, we do not include molecular adsorption of O 2 prior to dissociation. At such high temperatures, only atomic oxygen will exist on the surface. This occurs extremely quickly and fills most surface vacancies, leading to high oxygen surface coverages at the start of the catalyst, seen in the Supporting Information. CH 4 adsorbs much slower in comparison, mostly through dissociative adsorption, and immediately undergoes hydrogen dissociation 0.0 0.0 a Sticking coefficient (dimensionless); b pre-exponential factor for unimolecular reactions (s -1 ); c pre-exponential factor for bimolecular surface reactions (cm 2 mol -1 s -1 ); d pre-exponential factor for bimolecular surface and gas reactions (cm 3 mol -1 s -1 ); e pre-exponential factor for trimolecular reactions (cm 5 mol -2 s -1 ) until fully dehydrogenated. From there, C(s) can combine with oxygen and either desorb partially oxidized, or combine with additional oxygen and desorb fully oxidized. The influx of hydrogens on the surface from CH There is good agreement for species profiles between the Horn et al. C/O = 1.0 experiments and model simulations, as shown in Figure , with H 2 generation roughly 1.75 times more than CO generation. The production of water peaks around the same position as ex-periments, but there is less H 2 O conversion to additional synthesis gas products, as seen in the steam reforming zone that is mentioned in ref. 52. The RMG model had difficulties with predicting the amount of steam reformation, in this case underestimating the amount of H 2 produced, but was able to accurately predict the maximum amount of H 2 O.