Exploring the impact of coating strategies on temperature and emission characteristics of diesel particulate filters coated with selective catalytic reduction catalysts

Nitrogen oxides (NO_x) and particulate number (PN) emissions from internal combustion engines can be reduced by SDPF (diesel particulate filters coated with selective catalytic reduction (SCR) catalysts). The internal temperature of SDPF is significantly influenced by the SCR catalyst coating strategy, thereby affecting emission characteristics. Four SDPFs were prepared according to different coating strategies. The effects of the coating strategy on temperature characteristics, fuel consumption, emission characteristics and passive regeneration were studied through engine bench tests. The results indicate that the inlet temperature of the SDPF, coated once with a high-concentration catalyst, is lower at 441.19 °C and exhibits the best uniformity in internal temperature distribution, with a coefficient of variation (Cv) of 0.64 %. Conversely, the SDPF coated twice with low-concentration catalyst and the second coating 1/2 length of substrate inlet channel shows the poorest uniformity, with temperature difference of 113.63 °C and Cv of 9.07 %. The catalyst coating strategy has a little effect on fuel consumption, within 5.0 %. The SDPF coated once with high-concentration catalyst has the highest NO_x conversion rate, at 91.2 %, and the lowest total particulate number filtration efficiency, at 89.8 %. The selective catalytic reduction catalyst coating strategy has little effect on the passive regeneration of SDPF. Compared to the SDPF coated once with high-concentration catalyst, the SDPF coated twice with low-concentration catalyst has a higher pressure drop, with the maximum pressure drop increasing by 79.5 %.