Water Gas Shift and Methane Steam Reforming Kinetics on Pt+Pd/Al2O3 Monolith: Application to Emission Control of Stoichiometric Natural Gas Engines

Steam methane reforming (SMR) is an important CH4 conversion pathway in the catalytic emission control of stoichiometric natural gas vehicle exhaust. The water gas shift (WGS) reaction also occurs, which alters the ratio of the CO/H2 reductant ratio. Herein, we report the self-consistent development of global kinetic models for WGS and SMR on Pt+Pd/Al2O3. This is accomplished by a sequential development approach, first of WGS and then of SMR, enabling an accurate prediction of conversions and product distributions for both reaction systems. The global kinetic models account for conventional reactant effects, along with product inhibition. The study illustrates an efficient method of developing rate expressions directly from monolith catalyst experiments, enabling their direct incorporation into a 1 + 1 D monolith reactor model. The reactor model is applied to simulate the reactor performance for SMR including an assessment of the extent of external and washcoat transport limitations, among other aspects.