Experimental investigation to enhance the low-temperature nitrogen oxide emission reduction in biodiesel exhaust using selective catalytic reduction with direct ammonia injection and manganese cerium zirconia catalyst

Selective catalytic reduction (SCR) employs AdBlue, a reducing agent over a catalytic surface to reduce the oxides of nitrogen (NO_x) emission in diesel engines. SCR's inherent problem is its poor cold start performance at exhaust temperatures below 150°C. In the current work, the researcher has discussed the investigation of two techniques to enhance low-temperature NO_x conversion and combined them to achieve the best results. First, AdBlue injection was replaced by gaseous ammonia injection. The gaseous ammonia was generated by heating solid ammonia precursor materials such as solid urea and ammonium carbonate. Second, to improve the catalytic performance, MnCeZrO_x catalysts were introduced instead of conventional CuZ catalysts. MnCeZrO_x were prepared in the laboratory using its component materials. The prepared catalyst was tested through SEM and EDAX analysis. The newly developed SCR system was tested and compared with a conventional Adblue-CuZ SCR. The results revealed with diesel fuel at exhaust temperatures below 150°C the ammonia-MnCeZrO_x SCR system gave a 90% increase in NO_x reduction compared to the conventional system. With biodiesel blend jatropha B20 the conversion was greater than 80% from 100 to 150°C. A maximum NO_x conversion of 95% was obtained for diesel and 93% for jatropha Biodiesel blend B20.