Diesel oxidation catalysts (DOC) were investigated for oxidation activity, NO conversion stability, and sulfur poisoning/regeneration on Pd/Al2O3, Pt/Al2O3, and Pd–Pt/Al2O3 catalysts. The Pd/Al2O3 catalyst was more active for CO and hydrocarbon (C3H6 and C3H8) oxidation, while the Pt/Al2O3 catalyst efficiently oxidized NO. The formation of a Pd–Pt alloy in the Pd–Pt/Al2O3 catalyst maintained Pd in a more reduced phase, resulting in the superior activity of this catalyst for the oxidation of CO, C3H6, and NO in comparison with its monometallic counterparts. The Pd–Pt alloy not only provided more low-temperature activity but also retained the stability of NO oxidation. The Pd–Pt alloy also favored the spillover of SO2 to the alumina support, resulting in significantly higher adsorption capacity of the Pd–Pt/Al2O3 catalyst, extensively prolonging its lifetime. However, the stable sulfates on Pd–Pt/Al2O3 made it difficult to completely regenerate the catalyst. The bimetallic sample showed higher activity for CO, C3H8, and C3H6 after sulfur poisoning and regeneration.

The formation characteristics of N 2 O were investigated with respect to copper-functionalized zeolites, i.e., Cu/SSZ-13 (CHA), Cu/ZSM-5 (MFI), and Cu/BEA (BEA) and compared with the corresponding zeolites in the H form as references to elucidate the effect of the framework structure, copper addition, and water. Temperature-programmed reduction with hydrogen showed that the CHA framework has a higher concentration of Cu 2+ (Z2Cu) compared to MFI and BEA. The characterizations and catalyst activity results highlight that CHA has a framework structure that favors high formation of ammonium nitrate (AN) in comparison with MFI and BEA. Moreover, AN formation and decomposition were found to be promoted in the presence of Cu species. On the contrary, lower N 2 O formation was observed from Cu/CHA during standard and fast SCR reactions, which is proposed to be due to highly stabilized AN inside the zeolite cages. On the other hand, significant amounts of N 2 O were released during heating due to decomposition of AN, implying pros and cons of AN stability for Cu/CHA with possible uncontrolled N 2 O formation during transient conditions. Additionally, important effects of water were found, where water hinders AN formation and increases the selectivity for decomposition to NO 2 instead of N 2 O. Thus, less available AN forming N 2 O was observed in the presence of water. This was also observed in fast SCR conditions where all Cu/zeolites exhibited lower continuous N 2 O formation in the presence of water.

No abstract

No abstract

Titanium oxide (TiO x ) was employed for passivation layer of indium-gallium-zinc oxide (a-IGZO) TFTs. Molybdenum (Mo) and titanium (Ti) was used as a sourcedrain metal. It is demonstrated the titanium layer could be used as an etch stopper layer to protect the back channel of a-IGZO during Mo etching process and transformed into TiO x by the surface treatment using oxygen plasma. From device measurement, we have observed that I on /I off ratio and mobility are ~10 8 and 9 cm 2 V -1 sec -1 , respectively. AMLCD panel has been demonstrated to verify the device uniformity and performance.