Effect of TiO{sub}2 on the Reduction Performance of NO{sub}x Storage and Reduction Catalysts for Lean-Burn Natural Gas Vehicle

摘要

The effect of TiO{sub}2 on the reduction performance of NSR catalysts is investigated for lean-burn natural gas vehicles applications. Three types of NSR catalysts containing various amount of TiO{sub}2 are prepared to reduce NO{sub}x from the natural gas vehicle. In NSR catalysts, the main catalysts are composed of precious metals, Pt, Pd, Rh, and barium (Ba) which was used to adsorb the NO{sub}x in a lean engine condition. The catalytic reactions on NO{sub}x storage and reduction were estimated with the synthetic model gases. To examine the catalytic deactivation, the catalysts were aged under a laboratory hydrothermal aging mode. The characterizations of fresh and aged catalysts were carried out by SEM, TEM, and NOTPD. It was found that the addition of TiO{sub}2 in the NSR catalyst decreased a little bit of the NO{sub}x adsorption in comparison to the NSR catalyst without TiO{sub}2. At the catalyst temperature of 400°, the NO{sub}x reduction ratio of the fresh NSR catalyst containing 3.0 g/L TiO{sub}2 was almost the same level comparing with the NSR catalyst without TiO{sub}2. The amount of NO{sub}x adsorption of the aged NSR catalyst containing TiO{sub}2 increases a little comparing with the NSR catalyst without TiO{sub}2. The NO{sub}x reduction ratio of NSR catalyst is almost an equal level comparing to the NSR catalyst without TiO{sub}2. Therefore, we suggest that the optimum amount of TiO{sub}2 loaded to NSR catalyst should be about 3.0 g/L to increase durability of the NSR catalyst.