Promotional effect of ZrO2 and WO3 on bimetallic Pt-Pd diesel oxidation catalyst

• Published in: Environmental science and pollution research international Vol. 29; no. 4; pp. 5282 - 5294
• Main Authors: Fan, Rongrong, Li, Zhaoqiang, Wang, Yu, Wang, Yan, Ding, Zhiyong, Zhang, Cheng, Kang, Na, Guo, Xin, Wang, Rong
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01.01.2022; Springer Nature B.V
• Subjects: Additives; Aluminum oxide; Aquatic Pollution; Atmospheric Protection/Air Quality Control/Air Pollution; Bimetals; Carbon monoxide; Catalysts; Cerium oxides; Chemisorption; Conversion; Dispersion; Earth and Environmental Science; Ecotoxicology; Environment; Environmental Chemistry; Environmental Health; Environmental science; High temperature; hydrogen; Low temperature; Metal oxides; Noble metals; Oxidation; oxygen; Palladium; Platinum; Reduction (metal working); Research Article; species; temperature; Thermal stability; tungsten oxide; Tungsten oxides; Waste Water Technology; Water Management; Water Pollution Control; X ray photoelectron spectroscopy; Zirconium dioxide; Zirconia; Palladium; Diesel oxidation catalyst; Platinum; Tungsten; Bimetallic
• ISSN: 0944-1344; 1614-7499; 1614-7499
• DOI: 10.1007/s11356-021-15800-7

Diesel oxidation catalysts Pt-Pd-( y) ZrO 2 -( z) WO 3 /CeZrO x -Al 2 O 3 with total Pt & Pd loading of only 0.68 wt.% were prepared and investigated for oxidation activity and stability of CO, C 3 H 6 , and NO. Introduction of ZrO 2 greatly improved low-temperature activities and retained stability especially for CO and C 3 H 6 oxidation after treated at 800 °C. With the optimal loading amount of 6 wt% ZrO 2 , 2 wt% WO 3 was introduced to the system and showed higher activity. Reaction temperature for 50% CO and C 3 H 6 conversion declined to 160 and 181 °C, and the maximal NO conversion increased to 50%. By using XRD, TEM, CO chemisorption, XPS, and H 2 -TPR analysis, it was found that ZrO 2 could inhibit aggregation of Pt and Pd, improve metal dispersion, and increase surface-chemisorbed oxygen after high-temperature treatment, accounting for promoted performance. Also, there were more reducible oxide species in ZrO 2 -doped catalysts. ZrO 2 could induce reduction of noble metal oxides and surface ceria by weakening Pt-O-Ce interaction, which increased the ability to dissociate H 2 and spillover effect of dissociated hydrogen to ceria. Doping WO 3 increased metal dispersion of fresh samples and brought more Pt 0 species that were active sites for oxidation reactions. Thus, ZrO 2 and WO 3 could be effective additives for oxidation catalysts to synergistically improve their activities and thermal stability.