Abstract: Nitrogen oxide (NO_x) is produced from both stationary power generation and mobile transportation sources. To mitigate NO_x production, heterogeneous catalysis can serve either as the primary combustion method or as the after-treatment process. In power generation for household electricity, synthesis gas (syngas) combustion in Integrated Gasification Combined Cycle (IGCC) is a viable alternative to typical coal combustion in reducing emissions, though the NO_x emission is still too high. In the Rich Catalytic Quick Lean (RCQL) syngas combustion, NO_x reduction is achieved by avoiding high temperature combustion. Power generation is accomplished in two stages: a rich catalytic first stage followed by a lean second stage. In mobile transportation, NO_x emission from Diesel engines can be substantially reduced by ethanol Selective Catalytic Reduction (SCR) on silver alumina catalysts. By injecting ethanol in the exhaust and quickly mixing the two, researchers have found that more than 90% of NO _x can be converted back to nitrogen by passing the mixture through a silver alumina catalyst. In this study, a validated surface mechanism is used for designing a universal RCQL syngas burner, and a detailed surface mechanism is developed for ethanol SCR of NO on silver alumina catalyst. Through the two-dimensional rich catalytic syngas combustion simulations with detailed surface chemistry and transport in CURRENT, the preferential consumption of hydrogen over carbon monoxide on the platinum catalyst is observed. A direct consequence is that syngas with different hydrogen concentrations can be properly conditioned for the second stage lean combustion. Flame speed calculations with PREMIX show that the flame speed variations for the various syngas can be mitigated through the RCQL treatment. On the other hand, zero-dimensional Surface Perfectly-Stirred Reactor (SPSR) simulations with both gas-phase and surface chemistry are performed to develop a detailed surface mechanism with 35 reactions for ethanol SCR. Using the new surface SCR mechanism along with validated ethanol gas phase chemistry, the cause of the inactivity of ethanol SCR beyond 500°C is found to be the desorption of NO and ethanol rather than gas-phase ethanol oxidation. Predictions with the new ethanol SCR mechanism match well with the experimental NO_x conversion.