Experimental study on particle emission reduction and oxidation regeneration performance of CDPF: influence of Pt-Pd synergy and Ce modification

Catalytic diesel particulate filters (CDPFs) combine particulate filtration with catalyst assisted soot oxidation. However, the effects of Pt-Pd synergy and Ce modification on particulate emission reduction and oxidation regeneration performance under engine exhaust conditions require further investigation. In this study, Pt, Pt-Pd, and Pt-Pd-Ce loaded CDPFs with identical substrate specifications were investigated using engine bench tests. Their PN and PM reduction efficiencies, particle size distributions, soot accumulation characteristics, pressure drop recovery, temperature evolution, regeneration rates, and particle emissions during regeneration were systematically evaluated. The results show that Pt-Pd-Ce-CDPF achieves the highest average PN and PM reduction efficiencies of 98.4% and 99.3%, respectively. All three CDPFs remove accumulation mode particles more effectively than nucleation mode particles. The average soot accumulation rates of Pt-CDPF, Pt-Pd-CDPF, and Pt-Pd-Ce-CDPF are 1.16, 1.02, and 0.87 g/h, while their regeneration rates are 1.79, 2.01, and 2.55 g·L −1 /h, respectively. The corresponding complete regeneration times are 2.24, 1.99, and 1.57 h. Pressure drop recovery shows a rapid initial stage followed by a slower stage. Particle emissions during regeneration are dominated by transient nucleation mode burst windows. Pt-Pd-CDPF reduces the number and cumulative duration of significant burst windows to 10 and 91 s, while Pt-Pd-Ce-CDPF shows a lower mean PN concentration of 2.24 × 10 5 #/cm 3 at the peak particle diameter. Under the tested conditions, Pt-Pd-Ce-CDPF provides the best overall particulate emission reduction and oxidation regeneration performance.