Development of New Lean NOx Trap Technology with High Sulfur Resistance

Umeno, Takatoshi; Hanzawa, Masaya; Hayashi, Yoshiyuki; Hori, Masao

doi:10.4271/2014-01-1526

Cited by 11 publications

(8 citation statements)

References 13 publications

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“…Umeno, et al, (58) described an improved LNT with higher sulfur tolerance. The main NOx adsorbing material, barium oxide (baria) is supported on one basic material, and strontium oxide, which acts as a scavenger for the sulfur to protect the baria, is coated in the whole catalyst with high dispersion.…”

Section: Lean Nox Trap and Related Systemsmentioning

confidence: 97%

Review of Vehicular Emissions Trends

Johnson

2015

SAE Int. J. Engines

204

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This review paper summarizes major developments in vehicular emissions regulations and technologies from 2014. The paper starts with the key regulatory advancements in the field, including newly proposed Non-Road Mobile Machinery regulations for 2019-20 in Europe, and the continuing developments towards real driving emissions (RDE) standards. An expert panel in India proposed a roadmap through 2025 for clean fuels and tailpipe regulations. LD (light duty) and HD (heavy-duty) engine technology continues showing marked improvements in engine efficiency. Key developments are summarized for gasoline and diesel engines to meet both the emerging NOx and GHG regulations. HD engines are demonstrating more than 50% brake thermal efficiency using methods that can reasonably be commercialized. Next, NOx control technologies are summarized, including SCR (selective catalytic reduction), lean NOx traps, and combination systems. Emphasis is on durability and control. Diesel PM (particulate matter) reduction findings are evolving around the behavior of the soot cake and PM sensors. Gasoline particulates are further described and gasoline particulate filter regeneration is now better understood. Oxidation catalysts mainly involve developments towards stubborn problems, like sulfur tolerance, low-temperature performance with exhaust with high hydrocarbon and CO, and methane oxidation. Finally, the paper discusses some key developments in gasoline gaseous emission control, focusing on meeting new regulatory requirements in the US, durability, and on lean burn gasoline emissions control.

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Section: Lean Nox Trap and Related Systemsmentioning

confidence: 97%

Review of Vehicular Emissions Trends

Johnson

2015

SAE Int. J. Engines

204

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“…Furthermore, the rest of the main components of the NSR chemical composition such as ceria, alumina, and precious metals participate in the sulfur storage phenomena forming various types of sulfates, as it will be discussed later in this study. For this reason, the NSR catalyst needs to be periodically exposed at high temperatures up to 600–700°C and rich exhaust gas to remove sulfur and recover the NO x storage capacity and reduction efficiency of the catalyst …”

Section: Introductionmentioning

confidence: 99%

“…For this reason, the NSR catalyst needs to be periodically exposed at high temperatures up to 600-7008C and rich exhaust gas to remove sulfur and recover the NO x storage capacity and reduction efficiency of the catalyst. 12,13 Correspondence concerning this article should be addressed to G. Koltsakis at grigoris@auth.gr.…”

Section: Introductionmentioning

confidence: 99%

Modeling of the desulfation process in NO_x storage and reduction catalysts

et al. 2016

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One of the major challenges for the NOx Storage and Reduction Catalysts technology used in automotive exhaust remains the sulfur susceptibility, which calls for efficient desulfation strategies. The sulfation and desulfation processes are systematically studied via measurements and mathematical modeling of the physicochemical processes. The role of oxygen storage which influences the reducing agents availability for desulfation is explained and a respective reaction model is presented. The bulk oxygen storage component appears to be involved in sulfur storage, which further emphasizes the importance of oxygen–sulfur storage interactions. Next, the observed release of sulfur species under lean mode is discussed along with a proposed reaction mechanism which involves SO2 formation via O2 reaction with elemental sulfur on the surface. The parameters of the complex reaction model are calibrated in order to reproduce the observed trends at least in a qualitative manner. © 2016 American Institute of Chemical Engineers AIChE J, 63: 2117–2127, 2017

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“…Lubricants, such as zinc dialkyldithiophosphate (ZDDP), are commonly used in vehicles and are a source for accumulation of both sulfates, zinc and phosphorus in the catalyst [13]. The deactivation effect of sulfur has extensively been studied over LNTs [12,[14][15][16], and also how to regenerate the catalyst from sulfur [17].There are only a few studies available in the open literature where phosphorus poisoning has been studied over noble metal catalysts used for emission control. Bunting et al[13] studied a diesel oxidation catalyst (DOC) connected to an engine rig where the fuel was doped with ZDDP, which showed accumulation of foreign compounds such as phosphates, zinc and sulfates on the catalyst.…”

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confidence: 99%

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Gas-Phase Phosphorous Poisoning of a Pt/Ba/Al2O3 NOx Storage Catalyst

et al. 2018

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The effect of phosphorous exposure on the NO x storage capacity of a Pt/Ba/Al 2 O 3 catalyst coated on a ceramic monolith substrate has been studied. The catalyst was exposed to phosphorous by evaporating phosphoric acid in presence of H 2 O and O 2 . The NO x storage capacity was measured before and after the phosphorus exposure and a significant loss of the NO x storage capacity was detected after phosphorous exposure. The phosphorous poisoned samples were characterized by X-ray photoelectron spectroscopy (XPS), environmental scanning electron microscopy (ESEM), N 2 -physisorption and inductive coupled plasma atomic emission spectroscopy (ICP-AES). All characterization methods showed an axial distribution of phosphorous ranging from the inlet to the outlet of the coated monolith samples with a higher concentration at the inlet of the samples. Elemental analysis, using ICP-AES, confirmed this distribution of phosphorous on the catalyst surface. The specific surface area and pore volume were significantly lower at the inlet section of the monolith where the phosphorous concentration was higher, and higher at the outlet where the phosphorous concentration was lower. The results from the XPS and scanning electron microscopy (SEM)-energy dispersive X-ray (EDX) analyses showed higher accumulation of phosphorus towards the surface of the catalyst at the inlet of the monolith and the phosphorus was to a large extent present in the form of P 4 O 10 . However, in the middle section of the monolith, the XPS analysis revealed the presence of more metaphosphate (PO 3 − ). Moreover, the SEM-EDX analysis showed that the phosphorous to higher extent had diffused into the washcoat and was less accumulated at the surface close to the outlet of the sample.Catalysts 2018, 8, 155 2 of 15 periods of time the engine is switched from operating under lean to rich conditions. Under rich conditions, barium nitrates decompose and are reduced over the noble metal sites to mainly N 2 and H 2 O. The reducing agents in the exhaust gas are hydrocarbons (HC), carbon monoxide (CO) and hydrogen (H 2 ), which react with the NO x to produce CO 2 , H 2 O and N 2 . Nitrogen is the desired product from the reduction of stored nitrates. However, there are other possible bi-products from the reduction process such as ammonia (NH 3 ) and nitrous oxide (N 2 O) [3]. A vehicle is expected to be in service for a long time, which requires the catalyst to be durable. Over time, the catalytic properties of the catalyst deteriorate. There are a few mechanisms that contribute to degradation of catalysts, such as sintering of catalytic particles as a result of high-temperature exposure [11]. The catalytic washcoat can also undergo mechanical tear and poisoning of active sites on the catalyst caused by chemisorption or reactions of catalytically active sites with poisons in the exhaust gas [12]. The poisons are often introduced to the system through the gasoline or diesel fuel, which is the case for SO 2 , or through the lubricant of the engine. Lubricants, such as...

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Development of New Lean NOx Trap Technology with High Sulfur Resistance

Cited by 11 publications

References 13 publications

Review of Vehicular Emissions Trends

Review of Vehicular Emissions Trends

Modeling of the desulfation process in NO_x storage and reduction catalysts

Gas-Phase Phosphorous Poisoning of a Pt/Ba/Al2O3 NOx Storage Catalyst

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Development of New Lean NOx Trap Technology with High Sulfur Resistance

Cited by 11 publications

References 13 publications

Review of Vehicular Emissions Trends

Review of Vehicular Emissions Trends

Modeling of the desulfation process in NOx storage and reduction catalysts

Gas-Phase Phosphorous Poisoning of a Pt/Ba/Al2O3 NOx Storage Catalyst

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Product

Resources

About

Modeling of the desulfation process in NO_x storage and reduction catalysts