A numerical study of NOx removal from exhaust gas at low-temperature using metal Zeolite catalysts

With the growing emphasis on environmental protection, together with the recent EURO-6 European emission regulations, there has an increasing concern regarding the reduction of harmful substances in vehicle engine emissions at ambient temperatures, such as nitrogen oxides (NO_x) and particulate matter (PM). Selective Catalytic Reduction (SCR) has emerged as a way to mitigate low-temperature emissions from engines. This study focuses on analyzing the reduction characteristics of NO_x in engine exhaust by employing diverse copper/iron bimetallic catalysts through a numerical model. Experimental measurements at moderate to high temperatures were used to validate the numerical results. Subsequent simulations were conducted to examine, in detail, the performance of SCR converters at low temperatures. The findings suggest that varying the copper content in the catalyst can significantly enhance conversion efficiency at lower temperatures. While lower gas flow rates improve conversion efficiency, their effectiveness diminishes as the copper content in the catalyst increases. The effect of catalyst thickness is more pronounced at low temperatures and with lower copper content. Additionally, a higher inlet NO₂ concentration notably amplifies the conversion efficiency of the SCR process, particularly at lower temperatures.