Microkinetic model for the dry reforming of methane on Rh doped pyrochlore catalysts

•Created a microkinetic model of dry reforming of methane on a Rh-doped pyrochlore.•Computed overall methane conversion as a function of temperature and Rh loading.•Modeled inhibitory effects of competing reverse water gas shift reaction.•Observed a minimum Rh loading for DRM activity, approx. 0.4 wt% Rh.•Predicted low carbon deposition rates for the catalyst, matching experimental data.

Dry reforming of methane (DRM) is a promising gateway technology for energy and fuels production that utilizes methane and CO2, a common contaminant in natural gas deposits, as feed. Previous experimental work has shown that Rh-substituted lanthanum zirconate pyrochlores (LRhZ) are catalytically active and stable at the high temperatures needed for DRM. Although experimental and ab initio computational approaches have been used to study aspects of the DRM reaction mechanism on pyrochlores, this work is the first to describe a microkinetic model with variable reaction conditions and catalyst metal composition that uses parameters derived from DFT simulations for DRM over the (1 1 1) plane of an LRhZ pyrochlore catalyst. This model was used to gain insight into the favored reaction pathway for DRM and evaluate the time evolution of key intermediates (e.g., CH3, CH2, CH, OH, O) within the reactor at different reaction conditions and catalyst metal loading. Model predictions of reactant conversion and H2/CO product ratio were compared to experimental reaction data, and predicted yields compared well with experimental results.

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