Hybrid Technology for DeNOxing by LNT-SCR System for Efficient Diesel Emission Control: Influence of Operation Parameters in H₂O + CO₂ Atmosphere

• Main Authors: Marina Cortés-Reyes, Concepción Herrera, María Ángeles Larrubia, Luis J. Alemany
• Format: Article
• Language: English
• Published: MDPI AG 2020-02-01
• Series: Catalysts
• Subjects: nsr-scr hybrid catalysts; coupled aftertreatment technologies; denoxing; fixed double bed; no_x emission control
• Online Access: https://www.mdpi.com/2073-4344/10/2/228

The behavior and operation parameters were analyzed for the hybrid LNT-SCR (Lean NO_x-Trap−Selective Catalytic Reduction) system with advanced catalyst formulations. Pt-Ba-K/Al₂O₃ was used as an NSR (NO_x Storage and Reduction) or LNT catalyst effective in NO_x and soot simultaneous removal whereas Cu-SAPO-34 with 2 wt.% of copper inside the structure was the small pore zeolite employed as the SCR catalyst. Under alternating and cyclic wet conditions, feeding volumetric concentrations of 1000 ppm of NO, 3% of O₂, 1.5% of water, 0.3% of CO₂, and H₂ as a reductant, the NO_x-conversion values were above 95% and a complete mineralization to nitrogen was registered using θ ≤ 3 (20 s of regeneration) and a hydrogen content between 10,000 and 2000 ppm in the whole temperature range tested. An excess of hydrogen fed (above 1% v/v) during the rich phase is unnecessary. In addition, in the low temperature range below 250 °C, the effect is more noticeable due to the further ammonia production and its possible slip. These results open the way to the scale up of the coupled catalytic technologies for its use in real conditions while controlling the influence of the operation map.