Elucidating the mechanism of fast cycling NOx storage and reduction using C3H6 and H2 as reductants

Ting, Allen Wei-Lun; Harold, Michael P.; Balakotaiah, Vemuri

doi:10.1016/j.ces.2018.05.021

Cited by 17 publications

(6 citation statements)

References 22 publications

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“…Regarding the operation parameters, the time of the reduction phase or the ratio between oxidation/reduction period times is another open key point in the behaviour of these materials [31][32][33]. A decrease in the rich pulse length provokes a reduction in the NO x removal efficiency because insufficient time was available for the completely regeneration of the catalysts [22,34].…”

Section: Introductionmentioning

confidence: 99%

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

et al. 2020

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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/Al 2 O 3 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 O 2 , 1.5% of water, 0.3% of CO 2 , and H 2 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.

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Section: Introductionmentioning

confidence: 99%

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

et al. 2020

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“…Therefore, gas sensors are required to detect and monitor the regenerated H 2 with a moderate operating temperature, namely 150-300 °C. 26,27 H 2 sensors are also desired in gas separation engineering. For example, by using MFI-type zeolite membranes, multicomponent H 2 /hydrocarbon can be separated at various temperatures, from 25 to 300 °C, where an accurate and sensitive H 2 sensor is required to evaluate the efficiency of gas separation.…”

Section: Introductionmentioning

confidence: 99%

Selective H2 sensing using lanthanum doped zinc oxide thin film: A study of temperature dependence H2 sensing effect on carrier reversal activity

Ghosh

Zhang

et al. 2020

Journal of Applied Physics

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In the present work, we have demonstrated a highly sensitive H 2 gas sensor using a lanthanum doped ZnO (La_ZnO) thin film operated at 300 °C. Also, a p-type to n-type carrier reversal activity is revealed in the presence of H 2 gas species, which predominantly depends on the operating temperature and doping concentration of lanthanum. Pure and La_ZnO (1-10 at. %) thin films were successfully synthesized using a sol-gel route, where a 5 at. % lanthanum doped ZnO thin film shows an outstanding H 2 gas sensitivity (400%) among all other samples with an optimized temperature of 300 °C. Moreover, this sensor actively responds to a wide H 2 gas concentration (10-500 ppm) with a sensitivity of 0.9 (∼n). Additionally, H 2 gas sensing selectivity and mixed gas sensing performance were investigated in the presence of CO and CO 2 gas species at optimized temperature (300 °C). Results show that the pure and 1-3 at. % La_ZnO thin films exhibited n-type H 2 gas sensing, while p-type sensing behavior was observed for 5% and 10% La_ZnO thin films at 300 °C. It is further observed that O − species are extremely active to CO gas species operating at a high operating temperature (>250 °C). Therefore, despite the emerging p-type behavior of the sensor, the ejected electrons are expected to dominantly reduce the sensor resistance in the presence of CO gas species at 350 °C. The improvement of H 2 sensing is further interrelated with the defect levels using Raman spectroscopy.

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“…The NSR technology runs the engine under cyclic fuel-lean and -rich conditions, producing net oxidizing and reducing environments, respectively. Usually, lean period duration is on the order of few minutes, while rich period duration is few seconds. ,, During the lean period NO x are stored in barium sites in the form of nitrates and nitrites, and during the rich period, the stored NO x are released and reduced to N 2 , NH 3 , and N 2 O. One of the main drawbacks of the NSR technology is the emission of ammonia during the rich period. ,, …”

Section: Introductionmentioning

confidence: 99%

Influence of H₂, CO, C₃H₆, and C₇H₈ as Reductants on DeNO_x Behavior of Dual Monoliths for NO_x Storage/Reduction Coupled with Selective Catalytic Reduction

Urrutxua

Pereda‐Ayo

Trandafilović

et al. 2019

Ind. Eng. Chem. Res.

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The effects of feeding hydrogen, carbon monoxide, and propylene as reductants are analyzed in the combined NO x storage and reduction with selective catalytic reduction technology (NSR-SCR), with Pt−Ba/Al 2 O 3 and Pt− Ba−Ce/Al 2 O 3 monoliths as NSR catalysts, and Cu/BETA and Cu/SAPO-34 monoliths as SCR catalysts. Feed streams including CO 2 and H 2 O mimic the real composition of the diesel engine exhaust. Also, the reaction temperature and reductant concentration are analyzed on NO x removal and product distribution at the converter outlet. H 2 is the most efficient reductant at low temperature. The reducing capacity of CO is comparable to H 2 from 300 °C and onward. Higher temperature (400 °C) is needed for propylene to be as effective reductant as H 2 or CO due to the promotion of storage and reduction reaction. Benefits in dual NSR-SCR configurations are enhanced with H 2 as reductant, due to higher internal generation of NH 3 to be used in the SCR catalyst.

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Elucidating the mechanism of fast cycling NOx storage and reduction using C3H6 and H2 as reductants

Cited by 17 publications

References 22 publications

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

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

Selective H2 sensing using lanthanum doped zinc oxide thin film: A study of temperature dependence H2 sensing effect on carrier reversal activity

Influence of H₂, CO, C₃H₆, and C₇H₈ as Reductants on DeNO_x Behavior of Dual Monoliths for NO_x Storage/Reduction Coupled with Selective Catalytic Reduction

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Elucidating the mechanism of fast cycling NOx storage and reduction using C3H6 and H2 as reductants

Cited by 17 publications

References 22 publications

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

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

Selective H2 sensing using lanthanum doped zinc oxide thin film: A study of temperature dependence H2 sensing effect on carrier reversal activity

Influence of H2, CO, C3H6, and C7H8 as Reductants on DeNOx Behavior of Dual Monoliths for NOx Storage/Reduction Coupled with Selective Catalytic Reduction

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Influence of H₂, CO, C₃H₆, and C₇H₈ as Reductants on DeNO_x Behavior of Dual Monoliths for NO_x Storage/Reduction Coupled with Selective Catalytic Reduction