Fabrication and Characterization of the DOC/DPF Catalyst for the Diesel Engine Made Through the Nanoparticles on Powder Process

摘要

Noble metal nanoparticles such as Pt and Pd were fabricated on glucose powder using physical vapor deposition, the so-called "nanoparticles on powder (NPP) process." The nanoparticles were loaded on the surface of a honeycomb monolith to improve the catalytic efficiency of the catalytic converter (DOC/DPF) in the diesel engine. The DC magnetron sputter deposition method with a 99.95% pure metal target was adopted to form nanoparticles on the powder. The nanoparticles on glucose are easily synthesized to form the colloid by dissolving in water, and the monolith ceramic is dipped in the colloidal solution to load the nanoparticles on the surface of the ceramic's airflow channel. The fine nanoparticles were uniformly loaded on the surface of the monolith ceramic, and the surface of the ceramic supporters after heat treatment were analyzed via inductively coupled plasma atomic emission spectroscopy (ICP-AES), field emission scanning electron microscopy (FESEM), and high-resolution transmission electron microscopy (HRTEM). The sizes of the Pt and Pd nanoparticles on the powder were 2-3 and 3-5 nm, respectively. Agglomeration and enlargement of the metal nanoparticles were not observed even with the increase in the deposition time on the supporter powder until the 3,000 ppm concentration. The stability and uniform distribution of the nanoparticles on the whole surface of the airflow channel in the monolith were verified through TEM observation after high-temperature treatment.