A review on exhaust gas after-treatment of lean-burn natural gas engines – From fundamentals to application

Lott, Patrick; Casapu, Maria; Grunwaldt, Jan-Dierk; Deutschmann, Olaf

doi:10.1016/j.apcatb.2023.123241

Cited by 23 publications

(10 citation statements)

References 517 publications

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“…For the catalytic combustion of CH 4 under automotive exhaust conditions, NO, CO, and SO 2 could coexist in the exhaust gas mixture. 3,13,31 8a), while the presence of 0.1% CO led to reduced CH 4 conversions at 200−300 °C. Additionally, the introduction of 0.1% CO or 0.1% NO was found to increase the O 3 conversions below 200 °C (Figure 8b).…”

Section: Resultsmentioning

confidence: 99%

Low-Temperature Methane Combustion Using Ozone over Coβ Catalyst

Yasumura,

Nagai,

Miyazaki

et al. 2024

J. Am. Chem. Soc.

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Catalytic methane (CH 4 ) combustion is a promising approach to reducing the release of unburned methane in exhaust gas. Here, we report Co-exchanged β zeolite (Coβ) as an efficient catalyst for CH 4 combustion using O 3 . A series of ion-exchanged β zeolites (Co, Ni, Mn, Fe, and Pd) are subjected to the catalytic test, and Coβ exhibits a superior performance in a lowtemperature region (<100 °C). The results of X-ray absorption spectroscopy (XAS) and catalytic tests for Coβ with different Co loadings indicate the isolated Co species is the plausible active site. The reaction mechanism of CH 4 combustion over the isolated Co 2+ cation is theoretically investigated by the single-component artificial force-induced reaction (SC-AFIR) method to thoroughly search for possible reaction routes. The resulting path toward CO 2 formation shows an activation energy of 73 kJ/ mol for the rate-determining step and an exothermicity of 1025 kJ/mol, which supports the experimental results. During a long-term catalytic test for 160 h without external heating, the CH 4 conversion gradually decreases from 80 to 40%, but the conversion fully recovers after dehydration at 500 °C (0.5 h). The copresence of H 2 O and CO exhibits a negative impact on the catalytic activity, while NO and SO 2 do not markedly change the catalytic activity.

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Section: Resultsmentioning

confidence: 99%

Low-Temperature Methane Combustion Using Ozone over Coβ Catalyst

Yasumura,

Nagai,

Miyazaki

et al. 2024

J. Am. Chem. Soc.

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“…As estimated by the World Health Organization, air pollution is causing ∼7% of the world’s deaths each year. The automotive industry accounts for the release of a major portion of toxic air pollutants, such as carbon monoxide (CO), soot particulates, and nitrogen oxides (NO x ). − Volatile organic compounds (VOCs), released from various stationary chemical industries and indoor sources, are also identified as toxic air pollutants because of their carcinogenic nature. − Thus, the purification of these air pollutants at ambient conditions is of utmost importance for a sustainable ecosystem.…”

Section: Introductionmentioning

confidence: 99%

Review of Shape-Controlled CeO₂ Nanocatalysts for Purification of Auto-Exhaust Pollutants

Putla,

Kamali,

Swapna

et al. 2024

ACS Appl. Nano Mater.

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CeO2 (cerium dioxide or ceria) is a versatile material for industrial catalysis because of its reversible Ce4+/Ce3+ redox pair and tunable oxygen vacancies. Purification of air pollutants released from vehicles and stationary chemical industries is one of the imperative catalytic applications of CeO2. In this regard, significant efforts have been made to improve the properties of CeO2 by precisely controlling its’ particle shape. This fascinating shape-controlled strategy can stabilize the surface-enriched crystal facets with excellent redox properties, abundant surface oxygen vacancies, enhanced active-site accessibility, and high catalytic activities. The synergistic effect of doping and deposition of transition metals in improving the structure–activity properties of shape-controlled ceria is also unraveled for air pollution control. Thus, this review aims to summarize and elucidate the advances in the field of catalytic air pollution control using shape-controlled ceria-based nanomaterials. The adverse effects of four types of air pollutants, namely carbon monoxide, soot particulates, nitrogen oxides, and volatile organic compounds, while emphasizing the drawbacks and challenges associated with the current technologies were briefly provided. The role of various doped metals (Zr, Ti, Mn, Co, Fe, Ni, etc.) and deposited metals (Au, Pt, Pd, Ru, Ag, Cu, Mn, etc.) associated with the well-defined morphologies (rods, cubes, tubes, polyhedra, spheres, fibers, etc.) of ceria for air pollution control was meticulously discussed. We hope that this timely important review can provide promising strategies for the rational design of advanced ceria-based catalysts not only for air pollution control but also for important energy-related applications.

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“…A lean fuel-air mixture, for example, increases the risk of locally too lean zones due to inhomogeneities, as a result of which combustion can no longer be maintained and emissions of unburnt methane increase (CIMAC WG17 2014, Krivopolianskii et In addition, further tightening of emissions legislation is expected, which could bring methane emissions even further into focus. Consequently, questions regarding exhaust gas aftertreatment will remain relevant (Lott et al 2024). Following a retro t idea, the operating strategy should be optimised in terms of emissions while avoiding major physical modi cations to the engine.…”

Section: Introductionmentioning

confidence: 99%

“…In real exhausts, not only steam but also pollutants like carbon monoxide (CO), formaldehyde (CH 2 O), and nitrogen oxides (NO x ) interact with the catalyst, and sulfur-containing compounds such as hydrogen sul de (H 2 S) or sulfur oxides (SO x ) can act as a strong catalyst poison (Lott et al 2024). In this respect, optimized catalyst formulations can ensure high activity and stability.…”

Section: Introductionmentioning

confidence: 99%

Innovative Engine Test Bench Setup for Testing of Exhaust Gas Aftertreatment and detailed Gas Species Analysis for CNG-SI-Operation

Tomin,

Keller,

Wagner

et al. 2024

Preprint

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For an efficient reduction of methane slip, a precise understanding of exhaust gas aftertreatment under real conditions is essential. Since it is not possible to produce catalytic converters in near-series geometry on a laboratory scale, it is necessary to resort to significantly smaller sample catalysts. Therefore, an engine test bench was designed to ensure real operating conditions for such samples with the help of space velocity and temperature control. A comparison between the actual and reference values of the space velocity results in a small deviation of 0.1% on average. Furthermore, the pressure conditions at the catalyst have been measured showing a propagation of pressure oscillations from the engine outlet which in combination with the space velocity regulation show that real conditions could be applied to the catalyst sample. Subsequently the exhaust gas concentrations were monitored with a Fourier transform infrared spectrometer. The catalyst material used is Pd on Al2O3 common for methane oxidation. The measurements show that the CH4 conversion is higher under lean conditions, but is below complete conversion. In a final comparison between purely stoichiometric operation and dithering, the course of the CH4 conversion rate over the test period is examined more closely. In addition to sampling pre- and post-catalyst, the exhaust gas composition is measured spatially resolved within a catalyst channel using special measurement technology. In the temporal course of the CH4 emissions, a stabilising effect due to the change of the operating mode can be seen showing that dithering seems to prevent further deactivation.

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A review on exhaust gas after-treatment of lean-burn natural gas engines – From fundamentals to application

Cited by 23 publications

References 517 publications

Low-Temperature Methane Combustion Using Ozone over Coβ Catalyst

Low-Temperature Methane Combustion Using Ozone over Coβ Catalyst

Review of Shape-Controlled CeO₂ Nanocatalysts for Purification of Auto-Exhaust Pollutants

Innovative Engine Test Bench Setup for Testing of Exhaust Gas Aftertreatment and detailed Gas Species Analysis for CNG-SI-Operation

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A review on exhaust gas after-treatment of lean-burn natural gas engines – From fundamentals to application

Cited by 23 publications

References 517 publications

Low-Temperature Methane Combustion Using Ozone over Coβ Catalyst

Low-Temperature Methane Combustion Using Ozone over Coβ Catalyst

Review of Shape-Controlled CeO2 Nanocatalysts for Purification of Auto-Exhaust Pollutants

Innovative Engine Test Bench Setup for Testing of Exhaust Gas Aftertreatment and detailed Gas Species Analysis for CNG-SI-Operation

Contact Info

Product

Resources

About

Review of Shape-Controlled CeO₂ Nanocatalysts for Purification of Auto-Exhaust Pollutants