Selective catalytic reduction

About: Selective catalytic reduction is a research topic. Over the lifetime, 10502 publications have been published within this topic receiving 226291 citations.

Comparative Analysis on the Effects of Diesel Particulate Filter and Selective Catalytic Reduction Systems on a Wide Spectrum of Chemical Species Emissions

Abstract: Two methods, diesel particulate filter (DPF) and selective catalytic reduction (SCR) systems, for controlling diesel emissions have become widely used, either independently or together, for meeting increasingly stringent emissions regulations worldwide Each of these systems is designed for the reduction of primary pollutant emissions including particulate matter (PM) for DPF and nitrogen oxides (NOx) for SCR However, there have been growing concerns regarding the secondary reactions that these aftertreatment systems may promote, involving unregulated species emissions This study was performed to gain an understanding of the effects that these aftertreatment systems may have on the emission levels of a wide spectrum of chemical species found in diesel engine exhaust Samples were extracted using a source dilution sampling system designed to collect exhaust samples representative of real-world emissions Testing was conducted on a heavy-duty diesel engine with no aftertreatment devices to establish a bas

Emission abatement system utilizing particulate traps

Abstract: Emission abatement system. The system includes a source of emissions and a catalyst for receiving the emissions. Suitable catalysts are absorber catalysts and selective catalytic reduction catalysts. A plasma fuel converter generates a reducing gas from a fuel source and is connected to deliver the reducing gas into contact with the absorber catalyst for regenerating the catalyst. A preferred reducing gas is a hydrogen rich gas and a preferred plasma fuel converter is a plasmatron. It is also preferred that the absorber catalyst be adapted for absorbing NO x .

Adsorption and oxidation of NH3 over V2O5/AC surface

Abstract: V2O5/AC has been reported to be active for selective catalytic reduction (SCR) of NO with NH3 at around 200 °C and resistant to SO2 deactivation. To elucidate its SCR mechanism, adsorption and oxidation of NH3 over V2O5/AC are studied in this paper using TG, MS and DRIFTS techniques. It is found that the adsorption and oxidation of NH3 take place mainly at V O bond of V2O5. A higher V2O5 loading results in more NH3 adsorption on the catalyst. V2O5 contains both Brϕnsted and Lewis acid sites; NH4+ on Brϕnsted acid sites is less stable and easier to be oxidized than NH3 on Lewis acid sites. Gaseous O2 promotes interaction of NH3 with AC and oxidation of NH3 over V2O5/AC. NH3 is oxidized into NH2 and acylamide structures and then to isocyanate species, which is an intermediate for N2 formation.

Operando Spatially- and Time-Resolved XAS Study on Zeolite Catalysts for Selective Catalytic Reduction of NOx by NH3

Abstract: The structure of iron and copper sites during the selective catalytic reduction (SCR) of NOx by NH3 and related reactions (NH3 adsorption/oxidation, NO oxidation) has been elucidated by spatially- and time-resolved X-ray absorption spectroscopy (XAS) along the catalyst bed over Fe-containing BEA and ZSM-5 zeolites as well as Cu-SAPO-34 silicoaluminophosphate. Strong gradients of the Fe and Cu oxidation state are present along the catalyst bed for the processes involving NH3 and NOx (SCR) and less pronounced for NH3 oxidation, whereas the catalyst state in the NOx containing feed resembles that of a catalyst exposed to air. The variation in the oxidation state is strongly correlated to the concentration of NH3 and is more pronounced in the presence of NOx. For temperatures higher than 250 °C the Fe and Cu sites at the beginning of the catalyst bed stay in partially reduced state, whereas they are more oxidized in the later zones where NH3 and NO concentrations decrease. For temperatures lower than 250 °C a...