Modeling intraphase and interphase mass transfer limitations for NH3–SCR over Cu–ZSM–5

Abstract

Abstract A model describing NH3 selective catalytic reduction (NH3-SCR) over Cu-ZSM-5 to investigate the effects of intraphase and interphase mass transfer on standard SCR reaction is developed and further verified with the synthetic gas bench. The correlation between tortuosity and porosity has been analyzed by least squares method and applied to the sinuousoidal capillary bundle model. The effects of washcoat thicknesses, lengths, cell densities and channel widths on the standard SCR reaction are analyzed in temperature range of 150–500\u202f°C. It is found that deNOx efficiency is affected by intraphase diffusion limitations at 200–500\u202f°C and by interphase mass transfer limitation at intermediate (250–400\u202f°C) and high temperatures (400–500\u202f°C). As the temperature increases, the reaction is firstly controlled by kinetics, with the kinetics resistance decreasing and then increasing until the maximum among three processes. Furthermore, intake flow rates (GHSVs) play an important role impacting NO conversion on NH3–SCR.