Study of N2O Formation over Rh- and Pt-Based LNT Catalysts

Kubiak, Lukasz Maciej; Matarrese, Roberto; Castoldi, L.; Lietti, Luca; Daturi, Marco; Forzatti, Pio

doi:10.3390/catal6030036

Cited by 17 publications

(14 citation statements)

References 20 publications

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“…The NO2 and N2O emissions are higher at the Euro 6b vehicle, probably due to the LNT [37] that could also explain the N2O spikes of the Euro 6b vehicle. The NO2 concentration is reduced efficiently (middle panel) because the SCR has the appropriate temperature and the presence of NO2 enhances the SCR activity at lower temperatures [38].…”

Section: Comparison With the Euro 5b Retrofitmentioning

confidence: 97%

Emissions of a Euro 6b Diesel Passenger Car Retrofitted with a Solid Ammonia Reduction System

et al. 2019

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Nitrogen oxides (NOx) emissions from diesel vehicles are a serious environmental concern. Prior to the introduction of on-road tests at type approval, vehicle on-road NOx emissions were found many times higher than the applicable limits. Retrofitting an existing vehicle is a short/mid-term solution. We evaluated a NOx reduction retrofit system installed on a Euro 6b diesel passenger car both in the laboratory and on the road. The retrofit consisted of an under-floor SCR (selective catalytic reduction) for NOx catalyst in combination with a solid ammonia-based dosing system as the NOx reductant. The retrofit reduced NOx emissions from 25% (50 mg/km) to 82% (725 mg/km) both in the laboratory and on the road. The minimum reduction was achieved at cold start cycles and the maximum at hot start cycles. The retrofit had small effect on CO2 (fuel consumption). No ammonia emissions were detected and the N2O increase was negligible at cold start cycles, but up to 18 mg/km at hot start cycles. The results showed that the retrofit technology could be beneficial even for high emitting Euro 6b diesel vehicles.

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Section: Comparison With the Euro 5b Retrofitmentioning

confidence: 97%

Emissions of a Euro 6b Diesel Passenger Car Retrofitted with a Solid Ammonia Reduction System

et al. 2019

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“…The exhaust regulation on NO x emissions is getting more stringent [1]. Presently, NH 3 selective catalytic reduction (SCR) [2] and NO x storage reduction (NSR) [3] are widely used for NO x removal. However, standard NO x aftertreatment technologies fail to function efficiently at low temperatures, which results in a large proportion of the tailpipe NO x emission [4].…”

Section: Introductionmentioning

confidence: 99%

Investigation of Various Pd Species in Pd/BEA for Cold Start Application

et al. 2019

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A series of Pd/BEA catalysts with various Pd loadings were synthesized. Two active Pd2+ species, Z−-Pd2+-Z− and Z−-Pd(OH)+, on exchanged sites of zeolites, were identified by in situ FTIR using CO and NH3 respectively. Higher NOx storage capacity of Z−-Pd2+-Z− was demonstrated compared with that of Z−-Pd(OH)+, which was caused by the different resistance to H2O. Besides, lower Pd loading led to a sharp decline of Z−-Pd(OH)+, which was attributed to the ‘exchange preference’ for Z−-Pd2+-Z− in BEA. Based on this research, the atom utilization of Pd can be improved by decreasing Pd loading.

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“…Pérez-Ramírez et al [10] suggest that the coupling of ammonia intermediates (NHx) and nitric oxide is the exclusive route for N2O formation. The coupling of two adsorbed NO molecules, the recombination of an adsorbed NO molecule with an adsorbed NHx fragment, and the coupling of un-dissociated NO molecules with N• adspecies were considered to be possible pathways for N2O formation over a Pt−Ba/Al2O3 LNT catalyst, based on isotopic labeling experiments [11,12]. Due to the complexity of this reaction system, the reaction mechanisms of the whole system are complicated, and more fundamental studies are expected to provide further insights into the pathways involved in N2O formation.…”

Section: Introductionmentioning

confidence: 99%