(361d) Development of Low-Temperature SCR Catalysts for the Cold-Start Applications of NOx Reduction

Forthcoming low emissions standards for vehicles are forcing automobile and catalyst manufacturers to focus on reducing cold start NO_x emissions since a large portion of NO_x emissions occur during the cold start period. Consequently, control of emissions during the cold start operation of a vehicle containing an internal combustion engine is highly desirable. In pursue of our research interest in selective catalytic reduction (SCR) of NO_x, we prepared a series of TiO₂, TiO₂-SiO₂ (1:1 mole ratio) supported catalysts by adopting incipient wetness technique and investigated for the catalytic reduction of NO_x with ammonia. In order to simulate the realistic diesel exhaust conditions, we have evaluated the potential catalytic performance of all the prepared catalysts under industrially relevant conditions with excess (10 vol.%) oxygen in the feed. To our surprise, Cu/TiO₂ catalyst showed highly impressive low temperature deNO_x performance in the 150-200°C temperature regimes. The V/TiO₂, Ce/TiO₂ formulations achieved better stability in the temperature range of 200-350 °C, which will add several advantages over high temperature operations. Therefore, the effect of dopants, water vapors and SO₂ poisoning will be investigated. The chemical environment of these catalysts were characterized by using different spectroscopic and non-spectroscopic methods such as N₂ physisorption, temperature programmed reduction (TPR), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). More details about the reaction, durability of the catalysts and characterizations will be discussed in the presentation.