NH3 formation over a lean NOX trap (LNT) system: Effects of lean/rich cycle timing and temperature

DiGiulio, Christopher D.; Pihl, Josh A.; Choi, Jae‐Soon; Parks, James E.; Lance, Michael J.; Toops, Todd J.; Amiridis, Michael D.

doi:10.1016/j.apcatb.2013.09.012

Cited by 53 publications

(26 citation statements)

References 53 publications

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“…For example, Al 2 O 3 support favored the formation of methane and higher hydrocarbons, whereas supports such as TiO 2 and La 2 O 3 remarkably increased the yields of ethanol and other C 2 oxygenates, especially when there was a strong interaction between the support and active metal (SISM). CeO 2 has been widely used for the conversion of NO, CO, and hydrocarbons in the three-way catalysts (TWC) due to its high oxygen storage/release capacity [25]. In addition, it can also be used as a support [26] or a promoter [27] in the synthesis of ethanol, and has been claimed to result in the highest ethanol selectivity among several lanthanide oxide promoters [28].…”

Section: Introductionmentioning

confidence: 99%

The Promoting Effect of Fe Doping on Rh/CeO2 for the Ethanol Synthesis

et al. 2015

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The effects of Fe promotion were investigated on the activity and selectivity of Rh/CeO 2 catalyst for the direct synthesis of ethanol from syngas. The catalysts were comprehensively characterized by X-ray diffraction (XRD), N 2 adsorption-desorption, CO uptake, H 2 -TPR, temperature programmed surface reaction (TPSR), and FT-IR. XRD, CO uptake and FT-IR measurements indicated that Rh particles were well dispersed. TPSR results revealed that the addition of Fe changed CO dissociation behavior over the catalysts. FT-IR results showed that Fe promoter stabilized both linear carbonyl and gem-dicarbonyl species, which could be responsible for the improved catalytic activity. The interaction between Rh and Fe species is proposed to play a crucial role in achieving higher ethanol selectivity. Graphical Abstract

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Section: Introductionmentioning

confidence: 99%

The Promoting Effect of Fe Doping on Rh/CeO2 for the Ethanol Synthesis

et al. 2015

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“…They reported the highest selectivity of 87 % towards NH 3 for the lowest Pt dispersion. Other publications also reported a selectivity towards NH 3 of 75 % and higher for a variety of Pt/BaO/Al 2 O 3 catalysts [42–44] …”

Section: Resultsmentioning

confidence: 82%

Towards Green Ammonia Synthesis through Plasma‐Driven Nitrogen Oxidation and Catalytic Reduction

et al. 2020

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Ammonia is an industrial large‐volume chemical, with its main application in fertilizer production. It also attracts increasing attention as a green‐energy vector. Over the past century, ammonia production has been dominated by the Haber–Bosch process, in which a mixture of nitrogen and hydrogen gas is converted to ammonia at high temperatures and pressures. Haber–Bosch processes with natural gas as the source of hydrogen are responsible for a significant share of the global CO2 emissions. Processes involving plasma are currently being investigated as an alternative for decentralized ammonia production powered by renewable energy sources. In this work, we present the PNOCRA process (plasma nitrogen oxidation and catalytic reduction to ammonia), combining plasma‐assisted nitrogen oxidation and lean NOx trap technology, adopted from diesel‐engine exhaust gas aftertreatment technology. PNOCRA achieves an energy requirement of 4.6 MJ mol−1 NH3, which is more than four times less than the state‐of‐the‐art plasma‐enabled ammonia synthesis from N2 and H2 with reasonable yield (>1 %).

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“…As described below, an inhibition of the hydrogen (H 2 ) formation mechanism was supposed, as no CO was converted and no decrease in downstream lambda was observed. On the one hand, H 2 is a very effective reducing agent, especially at very low DeNO x temperatures [20][21][22][23]; on the other hand, it plays an important role in the detection of a complete NO x regeneration because of the hydrogen sensitivity of the oxygen [30] sensor downstream of the LNT. Catalytic hydrogen formation over a LNT with a comparable formulation was frequently mentioned in the literature [22,[24][25][26][27][28][29] and takes place according to the water gas shift (WGS) mechanism (1):…”

Section: Hydrogen Formationmentioning

confidence: 99%

Impact of cyclic lean–rich aging under DeSO x condition on the lean-gas light-off and hydrogen formation ability of a lean NO x trap (LNT)

Maurer¹,

Fortner²,

Holler³

et al. 2017

Automot. Engine Technol.

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In this paper, the aging impact of desulphation (DeSO x) procedures on lean NO x traps (LNT) was investigated. With accelerated aging procedures on an engine test bench and on a synthetic-gas test bench, LNTs were stressed with lean rich cycling under realistic desulphation conditions. Exhaust gas chassis dynamometer tests showed the impact on emissions of the lean rich treatment. High carbon monoxide (CO) slips were detected in NEDC tests during NO x regeneration (DeNO x). With light-off tests, the pattern of damage was further investigated. A pronounced deactivation in CO-rich gas conversion was found to be the main reason for the carbon monoxide emissions in the chassis dynamometer tests. A correlation between DeSO x duration (cumulated duration of rich pulses) and the inhibited CO conversion was observed. Determinations of oxygen storage capacities of aged catalysts indicated that the lean-rich cycling mainly damaged the ceria oxide of the LNT. Variations of the rich gas components indicated that hydrogen in the feed gas as well as in situ generated hydrogen out of feed gas components (steam reforming, water gas shift) is accountable for the degradation in carbon monoxide conversion in rich purges. Investigations for lower desulphation temperatures showed that the effect is negligible for temperature \350°C. Therefore, catalyst deactivation throughout NO x regeneration events with much lower temperatures than at DeSO x was not observed. As reference to other aging treatments used in the literature, samples aged hydrothermally at 750°C, a phosphorus poisoned and hydrothermally aged LNT as well as a LNT sample from a vehicle endurance run were compared to the DeSO x aged catalysts. All LNTs had the same conventional LNT coating.

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NH3 formation over a lean NOX trap (LNT) system: Effects of lean/rich cycle timing and temperature

Cited by 53 publications

References 53 publications

The Promoting Effect of Fe Doping on Rh/CeO2 for the Ethanol Synthesis

The Promoting Effect of Fe Doping on Rh/CeO2 for the Ethanol Synthesis

Towards Green Ammonia Synthesis through Plasma‐Driven Nitrogen Oxidation and Catalytic Reduction

Impact of cyclic lean–rich aging under DeSO x condition on the lean-gas light-off and hydrogen formation ability of a lean NO x trap (LNT)

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