Selective Catalytic Reduction of NOx over V2O5-WO3-TiO2 SCR Catalysts—A Study at Elevated Pressure for Maritime Pre-turbine SCR Configuration

Abstract

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Impact of gas phase reactions and catalyst poisons on the NH3-SCR activity of a V2O5-WO3/TiO2 catalyst at pre-turbine position

“…This behavior is in line with literature [7,8] and emphasizes the positive effect of elevated pressure on the performance of a V-based SCR catalyst. Several studies [8,9] have shown that the pressure does not change the reaction kinetics and that the increased conversion with elevated pressure is affected by the negative impact of decreased diffusivity. For the small hydraulic diameter (1,27 mm) of the monolithic channels used in the present study, the higher residence time was the dominant factor leading to significantly improved NOx conversion.…”

“…Kröcher et al [7] showed for a V-based catalyst that an increased pressure grants a significantly smaller catalyst volume but also that the decreased diffusion and increased partial pressures can hinder the standard SCR reaction. Experimental and modeling studies of Rammelt et al [8] and Christensen et al [9] indicated no change in catalytic activity and kinetics at elevated pressures, and only an increased adsorption of NH3 for V-based catalysts. In one of our earlier studies we reported the positive influence of pressure as well as the negative impact of propylene and SO2 for a Cu-SSZ-13 SCR catalyst.…”

Analysis of the Driving Altitude and Ambient Temperature Impact on the Conversion Efficiency of Oxidation Catalysts

“…The volumetric flow rate of the exhaust gas also suffers a direct variation and, consequently, the flow dwell time [27]. The dwell time increase improves the mass transfer of the pollutants toward the catalyst active sites, which implies higher conversion efficiency [28] and a reduction of the light-off temperature [29]. On the contrary, an increase in the volumetric flow rate reduces the dwell time, which decreases the conversion efficiency of the catalysts [30].…”

The Impact of Pressure and Hydrocarbons on NOx Abatement over Cu- and Fe-Zeolites at Pre-Turbocharger Position

“…In this regard, one of the most important parameters promoting the catalytic reaction is temperature and numerous solutions proposed over the years include a closer location of the catalytic system towards the engine [13]. For instance, a very promising increase in activity 2 of 17 was obtained by positioning the NH 3 -SCR catalyst in front of the turbocharger [14][15][16][17]. In addition to temperatures of up to 180 • C higher at this location [18], the residence time is enhanced due to the higher pressure.…”