Microkinetic modeling of spatially resolved autothermal CH4 catalytic partial oxidation experiments over Rh-coated foams

Measurement and analysis of spatial reactor profiles in high temperature catalysis research

“…In consequence the actual concentration of O 2 in immediate vicinity of the Rh surface is essentially zero and the surface coverage of oxygen at the Rh surface negligible [15]. Taking these results on Rhodium into account it has been argued by some groups [19] that the co-existence of H 2 and O 2 revealed by the spatial profiles [8,12] is solely due to the vanishing O 2 concentration at the Rh surface. Therefore it is an interesting question to study H 2 formation by CPO on a catalytic system where transport limitations are much less pronounced than on Rhodium, and it will be shown in the following that this is the case on Platinum.…”

“…At first glance it is surprising that H 2 and O 2 can co-exist in the gas phase over a Rh surface at temperatures around 1000 • C. To rationalize this finding, the profiles in Fig. 5 and similar profiles measured for other conditions on Rh were modeled in several follow up publications using different elementary step reaction mechanisms [15,16,19]. Both these model studies as well as other independent experimental studies measuring spatial profiles at varying pressure [14] revealed that methane CPO on Rh foams is nearly completely film transport limited for the stoichiometrically limiting component O 2 .…”

Modeling of the Interactions Between Catalytic Surfaces and Gas-Phase

“…(1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11) can principally be used in the numerical simulation of laminar as well as turbulent flow fields; the so-called Direct Numerical Simulations, DNS. In practice, however, the solution of the Navier-Stokes equations for turbulent flows demands a prohibitive amount of computational time due to the huge number of grid points needed to resolve the small scales of turbulence.…”

“…In the last few years, a capillary sampling technique has become popular to measure axial species profiles in channel-like structures but also in fixed bed reactors in situ [10,11,25,113]. In this technique, a small amount of gas is sucked into a very thin capillary.…”

“…However, intermediates formed on the surface may desorb as well and readsorb. Examples are the water molecule in partial oxidation of alkanes over noble metals [10,11] and NO 2 in NO x storage catalysts [12,13]. Desorbing intermediates and radicals may trigger chemical reactions in the gas-phase and by this open a competing reaction pathway.…”