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Keywords = DeNOxing

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20 pages, 3470 KiB  
Article
Hydrogen Supplementation in SI Engines: Enhancing Efficiency and Reducing Emissions with a Focus on Knock Phenomena
by Saugirdas Pukalskas, Alfredas Rimkus, Tadas Vipartas, Saulius Stravinskas, Donatas Kriaučiūnas, Gabrielius Mejeras and Andrius Ušinskas
Machines 2025, 13(7), 571; https://doi.org/10.3390/machines13070571 - 1 Jul 2025
Viewed by 330
Abstract
This study investigates the impact of hydrogen supplementation on the performance, efficiency, and emissions of a spark-ignition internal combustion engine, with a specific focus on knock phenomena. A Nissan HR16DE engine was modified to operate in a dual-fuel mode using gasoline (E95) and [...] Read more.
This study investigates the impact of hydrogen supplementation on the performance, efficiency, and emissions of a spark-ignition internal combustion engine, with a specific focus on knock phenomena. A Nissan HR16DE engine was modified to operate in a dual-fuel mode using gasoline (E95) and high-purity hydrogen. Hydrogen was injected via secondary manifold injectors and managed through a reprogrammable MoTeC ECU, allowing precise control of ignition timing and fuel delivery. Experiments were conducted across various engine speeds and loads, with hydrogen mass fractions ranging from 0% to 30%. Results showed that increasing hydrogen content enhanced combustion intensity, thermal efficiency, and stability. Brake specific fuel consumption decreased by up to 43.4%, while brake thermal efficiency improved by 2–3%. CO, HC, and CO2 emissions were significantly reduced. However, NOx emissions increased with higher hydrogen concentrations due to elevated combustion temperatures. Knock tendency was effectively mitigated by retarding ignition timing, ensuring peak in-cylinder pressure occurred at 14–15° CAD aTDC. These findings demonstrate the potential of hydrogen supplementation to reduce fossil fuel use and greenhouse gas emissions in spark ignition engines, while highlighting the importance of precise combustion control to address challenges such as knock and NOx formation. Full article
(This article belongs to the Special Issue Advanced Engine Energy Saving Technology)
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16 pages, 1982 KiB  
Article
Selective Catalytic Reduction of NO with H2 over Pt/Pd-Containing Catalysts on Silica-Based Supports
by Magdalena Jabłońska, Adrián Osorio Hernández, Jürgen Dornseiffer, Jacek Grams, Anqi Guo, Ulrich Simon and Roger Gläser
Catalysts 2025, 15(5), 483; https://doi.org/10.3390/catal15050483 - 15 May 2025
Viewed by 634
Abstract
Platinum- and/or palladium-containing silica-based supports were applied for the selective catalytic reduction of NOx with hydrogen (H2-SCR-DeNOx). To obtain enhanced activity and N2 selectivity below 150 °C, we varied the type and loading of noble metals (Pt [...] Read more.
Platinum- and/or palladium-containing silica-based supports were applied for the selective catalytic reduction of NOx with hydrogen (H2-SCR-DeNOx). To obtain enhanced activity and N2 selectivity below 150 °C, we varied the type and loading of noble metals (Pt and Pd both individually and paired, 0.1–1.0 wt.-%), silica-containing supports (ZrO2/SiO2, ZrO2/SiO2/Al2O3, Al2O3/SiO2/TiO2), as well as the H2 concentration in the feed (2000–4000 ppm). All of these contributed to enhancing N2 selectivity during H2-SCR-DeNOx over the (0.5 wt.-%)Pt/Pd/ZrO2/SiO2 catalyst in the presence of 10 vol.-% of O2. H2 was completely consumed at 150 °C. A comparison of the catalytic results obtained during H2-SCR-DeNOx,(H2-)NH3-SCR-DeNOx, as well as stop-flow H2-SCR-DeNOx and temperature-programmed studies, revealed that in the temperature range between 150 and 250 °C, the continuously coupled or overlaying mechanism of NO reduction by hydrogen and ammonia based on NH3 formation at lower temperatures, which is temporarily stored at the acid sites of the support and desorbed in this temperature range, could be postulated. Full article
(This article belongs to the Topic Advanced Materials in Chemical Engineering)
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30 pages, 30213 KiB  
Review
Development of Ammonia Combustion Technology for NOx Reduction
by Hossein Ali Yousefi Rizi and Donghoon Shin
Energies 2025, 18(5), 1248; https://doi.org/10.3390/en18051248 - 4 Mar 2025
Cited by 4 | Viewed by 1934
Abstract
This study comprehensively reviewed the engineering theories and technologies required for using ammonia as a fuel. The slow reaction rate and high NOx emissions of ammonia remain challenging issues with existing combustion technologies. Accordingly, the causes of these problems with ammonia were analyzed [...] Read more.
This study comprehensively reviewed the engineering theories and technologies required for using ammonia as a fuel. The slow reaction rate and high NOx emissions of ammonia remain challenging issues with existing combustion technologies. Accordingly, the causes of these problems with ammonia were analyzed and the results of research aimed at solving these issues and commercializing ammonia combustion were examined to explore future directions for the development of ammonia combustion technology. The equivalence ratio (ER) emerged as the most important factor, closely related to operational stability and NOx emissions. Various combustion technologies, such as staged combustion and flameless combustion, have been attempted, but NOx emissions remain high at overall ER < 1, necessitating post-treatment processes. The internal recirculation of combustion gases is a key technology that enhances the stability of ammonia combustion, and its extreme case, flameless combustion technology, is predicted to form stable ammonia combustion. This is related to supplying the radicals that are lacking in the pure ammonia combustion process through the recirculation of combustion gases. By utilizing this, if the stability of ammonia combustion is secured and staged ER control technology is established, it is believed that the commercialization of pure ammonia combustion technology will be possible in the future. Full article
(This article belongs to the Collection Feature Papers in Energy, Environment and Well-Being)
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22 pages, 12535 KiB  
Article
Numerical Modelling Assessment of the Impact of Hydrogen on the Energy and Environmental Performance of a Car Using Dual Fuel (Gasoline–Hydrogen)
by Saugirdas Pukalskas, Tadas Vipartas, Alfredas Rimkus, Donatas Kriaučiūnas, Justas Žaglinskis, Saulius Stravinskas, Andrius Ušinskas, Romualdas Juknelevičius, Gabrielius Mejeras, Vidas Žuraulis, Vilius Mejeras and Aleksas Narkevičius
Appl. Sci. 2025, 15(4), 1939; https://doi.org/10.3390/app15041939 - 13 Feb 2025
Cited by 1 | Viewed by 982
Abstract
The utilization of “green” hydrogen in transportation areas gives rise to production- and supply infrastructure-related challenges; therefore, its wider application in automotive transport would lead to higher demand with cost reduction and a faster expansion of the hydrogen refuelling network. This study presents [...] Read more.
The utilization of “green” hydrogen in transportation areas gives rise to production- and supply infrastructure-related challenges; therefore, its wider application in automotive transport would lead to higher demand with cost reduction and a faster expansion of the hydrogen refuelling network. This study presents energy and environmental performance indicators analyses of a Nissan Qashqai J10 engine during the Worldwide Harmonised Light Vehicles Test Cycle (WLTC), replacing conventional fossil gasoline with dual-fuel (D-F) gasoline and hydrogen. Numerical modelling was conducted using AVL Cruise™ (Version R2022.2) software, utilizing the torque, fuel consumption, and environmental performance data of the HR16DE engine obtained through experimental testing across a wide range of loads and speeds on an engine test bench. The experimental investigation was carried out in two stages: using pure gasoline (G100); injecting a hydrogen additive into the intake air, constituting 5% of the gasoline mass (G95H5). Following similar stages, numerical modelling was conducted using the vehicle’s technical specifications to calculate engine load and speed throughout the WLTC range. Instant fuel consumption and pollutant emissions (CO, CH, NOx) were determined for various driving modes using experimental data maps. CO2 emissions were calculated considering fuel composition and consumption. By integrating the instant values, the total and specific fuel consumption and emissions were calculated. As a result, this study identified the effect of a 5% hydrogen additive in improving engine energy efficiency, reducing incomplete combustion products and lowering greenhouse gas (CO2) emissions under various driving modes. Finally, the results were compared with the requirements of EU standards. Full article
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17 pages, 18261 KiB  
Article
Reactive Dicarbonyl Scavenging with 2-Hydroxybenzylamine Improves MASH
by Joyce Cheung-Flynn, John A. Rathmacher, Lisa M. Pitchford, Yanhua Xiong and Charles Robert Flynn
Nutrients 2025, 17(4), 610; https://doi.org/10.3390/nu17040610 - 7 Feb 2025
Cited by 1 | Viewed by 3500
Abstract
Background: Products of lipid peroxidation include a number of reactive lipid aldehydes including reactive dicarbonyl electrophiles (DEs) and contribute to disease processes. DEs play a significant role in the development and progression of metabolic-associated steatotic liver disease (MASLD) by contributing to oxidative stress, [...] Read more.
Background: Products of lipid peroxidation include a number of reactive lipid aldehydes including reactive dicarbonyl electrophiles (DEs) and contribute to disease processes. DEs play a significant role in the development and progression of metabolic-associated steatotic liver disease (MASLD) by contributing to oxidative stress, inflammation, protein dysfunction, and mitochondrial impairment. Reducing DE stress may be a potential strategy for managing MASLD. We hypothesized that the DE scavenger 2-hydroxybenzylamine (2-HOBA) would reduce liver injury by reducing liver protein adduct formation by DE in mouse models of MASLD. Methods: Protein adducts were measured in human livers by immunohistochemistry and immunoblot. The effects of 2-HOBA were assessed in two different mouse models of MASLD. Results: Isolevuglandin (IsoLG) protein adducts were increased in MASH-staged human livers relative to histologically normal controls. Diet-Induced Animal Model of Nonalcoholic Fatty Liver Disease (DIAMOND) mice treated with 2-HOBA exhibited significantly lower fibrosis scores (* p = 0.012) and reduced liver transaminases (AST, p = 0.03) and ALT, p = 0.012) by over 40%. In STAM (Stelic Animal Model) mice, 2-HOBA improved NAFLD activity scores (p = 0.03, NAS), hyperglycemia, and inflammatory cytokines and reduced serum F2-isoprostanes (IsoPs) by 30%, p = 0.05. These improvements were absent mRNA changes in hepatic antioxidant enzymes (Cat, Gpx1, or Sod2) or ROS-generating proteins (p22PHOX, p47PHOX, NOX4 or COX1). Conclusions: DE scavenging with 2-HOBA may be a promising therapeutic strategy for managing MASLD. While findings are currently limited to male mice, a nutraceutical that reduces liver fibrosis could significantly improve the management of MASH by offering a non-invasive treatment option to potentially slow or reverse liver scarring, delay progression to cirrhosis, and improve patient outcomes, while also providing a potential treatment option for patients who may not be suitable for other interventions like liver transplantation. Full article
(This article belongs to the Special Issue Hot Topics in Clinical Nutrition (3rd Edition))
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16 pages, 5232 KiB  
Article
Numerical Simulation of Static Ammonia Mixer in Denox Unit of Flue Gas Purification Plant
by Anton L. Esipovich, Andrey V. Vorotyntsev, Andrey A. Roslyakov, Dmitry E. Sykhanov, Olga A. Demchenko, Anton V. Stepykin and Konstantin K. Shirshin
Energies 2025, 18(2), 295; https://doi.org/10.3390/en18020295 - 10 Jan 2025
Viewed by 668
Abstract
The modeling of a mixer used for mixing ammonia and flue gasses is considered. Simulations were performed using Flow Vision 3.14 (TESIS LLC). As a result of the simulation, the distribution of concentrations along the mixer length was obtained at 50%, 65%, 85%, [...] Read more.
The modeling of a mixer used for mixing ammonia and flue gasses is considered. Simulations were performed using Flow Vision 3.14 (TESIS LLC). As a result of the simulation, the distribution of concentrations along the mixer length was obtained at 50%, 65%, 85%, and full flue gas loading. It was found that operations at 100% and 85% gas loads are accompanied by an acceptable distribution of ammonia in the mixer volume (Cov = 0.05). The development and creation of an experimental model in real production was carried out according to the results of the numerical simulation. The simulation results were compared with experimental data on the speed and concentration of ammonia in the control section. The discrepancy, in general, did not exceed 15%. The developed mixer corresponds to modern developments in terms of mixing quality but is simpler in design and more compact. Full article
(This article belongs to the Section J1: Heat and Mass Transfer)
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16 pages, 3993 KiB  
Article
Transformation of NO in Combustion Gases by DC Corona
by Oleksandr Molchanov, Kamil Krpec, Jiří Horák, Lenka Kuboňová, František Hopan, Jiří Ryšavý and Marcelina Bury
Fire 2025, 8(1), 21; https://doi.org/10.3390/fire8010021 - 8 Jan 2025
Viewed by 1034
Abstract
This study investigates the performance of DC corona discharge electrostatic precipitators (ESPs) for NO conversion to increase DeNOx technologies’ efficiency for small-scale biomass combustion systems. Experiments were conducted using a 5 kW automatic wood pellet domestic heat source with combustion gas treated [...] Read more.
This study investigates the performance of DC corona discharge electrostatic precipitators (ESPs) for NO conversion to increase DeNOx technologies’ efficiency for small-scale biomass combustion systems. Experiments were conducted using a 5 kW automatic wood pellet domestic heat source with combustion gas treated in a specially designed ESP operated in both positive and negative corona modes, resulting in a reduction in NO concentrations from 130 mg/m3 to 27/29 mg/m3 for positive/negative polarities (at 0 °C and 101.3 kPa). NO conversion efficiency was evaluated across a range of specific input energies (SIEs) from 0 to 50 J/L. The results demonstrate that DC corona ESPs can achieve up to 78% NO reduction, with positive corona demonstrating a greater energy efficiency, requiring a lower SIE (35 J/L) compared to the negative corona mode (48 J/L). A detailed analysis of reaction pathways revealed distinct conversion mechanisms between the two modes. In positive corona, dispersed active species distribution led to more uniform NO conversion, while negative corona exhibited concentrated reaction zones with about 20% higher ozone production. The reactions involving O and OH radicals were more important in positive corona, whereas ozone-mediated oxidation dominated in negative corona. The research results demonstrate that ESP technology with DC corona offers a promising, energy-efficient solution for NOx control in small-scale combustion systems. Full article
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20 pages, 2939 KiB  
Article
Transition Metal Oxides Supported on TiO2 as Catalysts for the Low-Temperature Selective Catalytic Reduction of NOx by NH3
by Michael Liebau, Wolodymyr Suprun, Marcus Kasprick and Roger Gläser
Catalysts 2025, 15(1), 22; https://doi.org/10.3390/catal15010022 - 30 Dec 2024
Cited by 2 | Viewed by 1080
Abstract
The conversion of NOx and the yield of N2O during NH3-SCR-DeNOx below 473 K over TiO2-supported transition metal oxide catalysts with equal loading of 20 wt.-% decreases in the following order of the supported oxides: [...] Read more.
The conversion of NOx and the yield of N2O during NH3-SCR-DeNOx below 473 K over TiO2-supported transition metal oxide catalysts with equal loading of 20 wt.-% decreases in the following order of the supported oxides: MnOx > CuOx > CoOx > FeOx > NiOx > CeOx. The storage capacity for NH3, characterized by the acid site density of the catalyst, is not directly correlated with the catalytic activity. Rather, the temperature range for the reduction of the supported transition metal oxides as determined by TPR-H2 is the main governing factor for high NH3-SCR-DeNOx activity, especially in the temperature range below 473 K. At the same time, oxidation temperature range and the density of Lewis acid sites govern the formation of N2O. The decomposition of NH4NO3 as an intermediate in the NH3-SCR-DeNOx reaction is determined by the redox property of TMO-based catalysts, which further influences both the windows of the decomposition temperature and the yield of N2O. The correlation between the redox properties and the activity for NH3-SCR-DeNOx was confirmed for a series of MnOx-CeOx/TiO2-SiO2 mixed transition metal oxide catalysts as a promising combination of the less active and more selective CeOx with less selective and highly active MnOx. The linear correlation between reduction temperature range and the NH3-SCR-DeNOx activity indicates that the found relation can be transferred to other supported transition metal-containing catalysts for low-temperature NH3-SCR-DeNOx. Full article
(This article belongs to the Special Issue Catalytic Reactions in Hydrogen and Ammonia Economy)
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17 pages, 2736 KiB  
Article
Effects of Decanol Blended Diesel Fuel on Engine Efficiency and Pollutant Emissions
by Kwonwoo Jang, Jeonghyeon Yang, Beomsoo Kim and Jaesung Kwon
Energies 2024, 17(24), 6223; https://doi.org/10.3390/en17246223 - 10 Dec 2024
Cited by 1 | Viewed by 940
Abstract
This study examined the effects of blending decanol, an oxygenated fuel, with diesel on diesel engine performance and emissions. Experiments were conducted on a single-cylinder engine at 1700 rpm and 2700 rpm, using diesel/decanol blends at 10%, 30%, and 50% by volume (D90de10, [...] Read more.
This study examined the effects of blending decanol, an oxygenated fuel, with diesel on diesel engine performance and emissions. Experiments were conducted on a single-cylinder engine at 1700 rpm and 2700 rpm, using diesel/decanol blends at 10%, 30%, and 50% by volume (D90de10, D70de30, D50de50). Results showed that brake thermal efficiency decreased with higher decanol ratios at low speeds. As a result, brake specific fuel consumption and brake specific energy consumption increased due to decanol’s lower calorific value. Regarding emissions, decanol blending reduced NOx, CO, HC, and smoke. NOx emissions were lowered by the cooling effect resulting from decanol’s higher latent heat of vaporization and lower calorific value, especially at low speeds. CO and HC emissions declined as decanol’s oxygen content promoted oxidation, reducing incomplete combustion. Smoke emissions were minimized in fuel-rich zones by preventing unburned carbon particle formation. This study highlights decanol’s potential as an eco-friendly diesel blending option. Future work should optimize blending ratios and injection settings to enhance diesel engine performance. Full article
(This article belongs to the Special Issue Renewable Fuels for Internal Combustion Engines: 2nd Edition)
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16 pages, 4809 KiB  
Article
The Effect of CeO2 on the Catalytic Activity and SO2 Resistance of the V2O5-MoO3/TiO2 Catalyst Prepared Using the Ball Milling Method for the NH3-SCR of NO
by Xuehong Zi, Jingtong Ye, Yao Cheng, Shuangye Li, Xiangru Li, Xingtong Li, Wenge Qiu and Liyun Song
Catalysts 2024, 14(11), 794; https://doi.org/10.3390/catal14110794 - 7 Nov 2024
Cited by 1 | Viewed by 1108
Abstract
V2O5-WO3(MoO3)/TiO2 catalysts are widely used in industrial denitrification (deNOx) processes based on the selective catalytic reduction (SCR) technique. To lower their cost and shorten the production cycle, V2O5-MoO [...] Read more.
V2O5-WO3(MoO3)/TiO2 catalysts are widely used in industrial denitrification (deNOx) processes based on the selective catalytic reduction (SCR) technique. To lower their cost and shorten the production cycle, V2O5-MoO3/TiO2 catalysts with and without CeO2 modification were prepared using the ball milling method. This study demonstrates that the CeO2-modified catalyst has high NO conversion and a broader temperature window due to the decreased amount of easily reducible vanadium species and the enhanced property of oxygen species activation in CeO2. Meanwhile, the SO2 resistance of the catalyst is restrained due to the strong adsorption and oxidation of SO2 over CeO2 in the catalyst. Full article
(This article belongs to the Section Catalytic Materials)
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27 pages, 10241 KiB  
Article
The Effect of Bioalcohol Additives on Biofuel Diesel Engines
by Chengfang Mao, Jiewen Wei, Wangsheng Lan and Ananchai Ukaew
Fire 2024, 7(11), 404; https://doi.org/10.3390/fire7110404 - 4 Nov 2024
Cited by 1 | Viewed by 1260
Abstract
This study experimentally investigated a water-cooled four-cylinder turbocharged diesel engine (DE) under different loads and fuel blend ratios. The integration of Computational Fluid Dynamics (CFD) simulations enables a deeper analysis of the combustion process. Through an in-depth analysis of the combustion process, the [...] Read more.
This study experimentally investigated a water-cooled four-cylinder turbocharged diesel engine (DE) under different loads and fuel blend ratios. The integration of Computational Fluid Dynamics (CFD) simulations enables a deeper analysis of the combustion process. Through an in-depth analysis of the combustion process, the focus was placed on investigating the specific impacts of ethanol and n-butanol additives on diesel engine performance. Research shows that a fuel mixture consisting of 70% diesel, 10% biodiesel, and 20% ethanol reduced NOx emissions by 5.56% compared to pure diesel at 75% load. Furthermore, this study explores the combustion performance of diesel/biodiesel blended with butanol/ethanol. The findings indicate that n-butanol improves thermal efficiency, particularly at 100% load, with the D70B10E20 and D70B10BU20 blends demonstrating thermal efficiencies of 9.94%and 8.72% higher than that of diesel alone, respectively. All mixed fuels exhibited reduced hydrocarbon and CO emissions under different loads, with a notable reduction in hydrocarbon emissions of 34.4% to 46.1% at 75% load. Full article
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17 pages, 4438 KiB  
Article
Significant Effects of Adding Mode on Low-Temperature De-NOx Performance and SO2 Resistance of a MnCeTiOx Catalyst Prepared by the Co-Precipitation Method
by Xi Yang, Hongyan Xue, Lei Wang, Jun Yu, Lupeng Han and Dongsen Mao
Catalysts 2024, 14(10), 690; https://doi.org/10.3390/catal14100690 - 4 Oct 2024
Viewed by 1030
Abstract
Three MnCeTiOx catalysts with the same composition were prepared by conventional co-precipitation (MCT-C), reverse co-precipitation (MCT-R), and parallel co-precipitation (MCT-P), respectively, and their low-temperature SCR performance for de-NOx was evaluated. The textural and structural properties, surface acidity, redox capacity, and reaction [...] Read more.
Three MnCeTiOx catalysts with the same composition were prepared by conventional co-precipitation (MCT-C), reverse co-precipitation (MCT-R), and parallel co-precipitation (MCT-P), respectively, and their low-temperature SCR performance for de-NOx was evaluated. The textural and structural properties, surface acidity, redox capacity, and reaction mechanism of the catalysts were investigated by a series of characterizations including N2 adsorption and desorption, XRD, SEM, XPS, H2-TPR, NH3-TPD, NO-TPD, and in situ DRIFTs. The results revealed that the most excellent catalytic performance was achieved on MCT-R, and more than 90% NOx conversion can be obtained at 100–300 °C under a high GHSV of 80,000 mL/(gcat·H). Furthermore, MCT-R possessed optimal tolerance to H2O and SO2 poisoning. The excellent catalytic performance of MCT-R can be attributed to its larger BET specific surface area; higher contents of Mn4+, Ce3+, and adsorbed oxygen species; and more adsorption capacity for NH3 and NO. Moreover, in situ DRIFTs results indicated that the NH3-SCR reaction follows simultaneously the Langmuir–Hinshelwood and Eley–Rideal mechanisms at 100 °C. By adjusting the adding mode during the co-precipitation process, excellent low-temperature de-NOx activity of MCT-R can be obtained simply and conveniently, which is of great practical value for the preparation of a MnCeTiOx catalyst for denitrification. Full article
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23 pages, 6442 KiB  
Article
Numerical Study on Optimization of Combustion Cycle Parameters and Exhaust Gas Emissions in Marine Dual-Fuel Engines by Adjusting Ammonia Injection Phases
by Martynas Drazdauskas and Sergejus Lebedevas
J. Mar. Sci. Eng. 2024, 12(8), 1340; https://doi.org/10.3390/jmse12081340 - 7 Aug 2024
Cited by 5 | Viewed by 2384
Abstract
Decarbonizing maritime transport hinges on transitioning oil-fueled ships (98.4% of the fleet) to renewable and low-carbon fuel types. This shift is crucial for meeting the greenhouse gas (GHG) reduction targets set by the IMO and the EU, with the aim of achieving climate [...] Read more.
Decarbonizing maritime transport hinges on transitioning oil-fueled ships (98.4% of the fleet) to renewable and low-carbon fuel types. This shift is crucial for meeting the greenhouse gas (GHG) reduction targets set by the IMO and the EU, with the aim of achieving climate neutrality by 2050. Ammonia, which does not contain carbon atoms that generate CO2, is considered one of the effective solutions for decarbonization in the medium and long term. However, the concurrent increase in nitrogen oxide (NOx) emissions during the ammonia combustion cycle, subject to strict regulation by the MARPOL 73/78 convention, necessitates implementing solutions to reduce them through optimizing the combustion cycle. This publication presents a numerical study on the optimization of diesel and ammonia injection phases in a ship’s medium-speed engine, Wartsila 6L46. The study investigates the exhaust gas emissions and combustion cycle parameters through a high-pressure injection strategy. At an identified 7° CAD injection phase distance between diesel and ammonia, along with an optimal dual-fuel start of injection 10° CAD before TDC, a reduction of 47% in greenhouse gas emissions (GHG = CO2 + CH4 + N2O) was achieved compared to the diesel combustion cycle. This result aligns with the GHG reduction target set by both the IMO and the EU for 2030. Additionally, during the investigation of the thermodynamic combustion characteristics of the cycle, a comparative reduction in NOx of 4.6% was realized. This reduction is linked to the DeNOx process, where the decrease in NOx is offset by an increase in N2O. However, the optimized ammonia combustion cycle results in significant emissions of unburnt NH3, reaching 1.5 g/kWh. In summary, optimizing the combustion cycle of dual ammonia and diesel fuel is essential for achieving efficient and reliable engine performance. Balancing combustion efficiency with emission levels of greenhouse gases, unburned NH3, and NOx is crucial. For the Wartsila 6L46 marine diesel engine, the recommended injection phasing is A710/D717, with a 7° CAD between injection phases. Full article
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19 pages, 4209 KiB  
Article
Post-Synthetically Treated ERI and SSZ-13 Zeolites Modified with Copper as Catalysts for NH3-SCR-DeNOx
by Alejandro Mollá Robles, Gabriele Deplano, Kinga Góra-Marek, Marek Rotko, Anna Wach, Muhammad Fernadi Lukman, Marko Bertmer, Matteo Signorile, Silvia Bordiga, Andreas Pöppl, Roger Gläser and Magdalena Jabłońska
Catalysts 2024, 14(7), 457; https://doi.org/10.3390/catal14070457 - 16 Jul 2024
Cited by 1 | Viewed by 1856
Abstract
ERI and SSZ-13 were subjected to post-synthetic treatments (depending on the zeolite topology) to create micro-/mesoporous materials. The results in terms of NH3-SCR-DeNOx show that the applied treatments improved the catalytic activity of the Cu-containing ERI-based materials; however, the NO [...] Read more.
ERI and SSZ-13 were subjected to post-synthetic treatments (depending on the zeolite topology) to create micro-/mesoporous materials. The results in terms of NH3-SCR-DeNOx show that the applied treatments improved the catalytic activity of the Cu-containing ERI-based materials; however, the NO conversion did not vary for the different materials treated with NaOH or NaOH/HNO3. For the micro-/mesoporous Cu-containing SSZ-13, a lower NO conversion in NH3-SCR-DeNOx was observed. Thus, our findings challenge the current paradigm of enhanced activity of micro-/mesoporous catalysts in NH3-SCR-DeNOx. The modification of the supports results in the presence of different amounts and kinds of copper species (especially isolated Cu2+ and aggregated Cu species) in the case of ERI- and SSZ-13-based samples. The present copper species further differentiate the formation of reactive reaction intermediates. Our studies show that besides the μ-η22-peroxo dicopper(II) complexes (verified by in situ DR UV-Vis spectroscopy), copper nitrates (evidenced by in situ FT-IR spectroscopy) also act as reactive intermediates in these catalytic systems. Full article
(This article belongs to the Section Catalytic Materials)
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18 pages, 8308 KiB  
Article
Mechanisms for deNOx and deN2O Processes on FAU Zeolite with a Bimetallic Cu-Fe Dimer in the Presence of a Hydroxyl Group—DFT Theoretical Calculations
by Izabela Kurzydym and Izabela Czekaj
Molecules 2024, 29(10), 2329; https://doi.org/10.3390/molecules29102329 - 15 May 2024
Cited by 1 | Viewed by 1238
Abstract
In this paper, a detailed mechanism is discussed for two processes: deNOx and deN2O. An FAU catalyst was used for the reaction with Cu-Fe bimetallic adsorbates represented by a dimer with bridged oxygen. Partial hydration of the metal centres in the [...] Read more.
In this paper, a detailed mechanism is discussed for two processes: deNOx and deN2O. An FAU catalyst was used for the reaction with Cu-Fe bimetallic adsorbates represented by a dimer with bridged oxygen. Partial hydration of the metal centres in the dimer was considered. Ab initio calculations based on the density functional theory were used. The electron parameters of the structures obtained were also analysed. Visualisation of the orbitals of selected structures and their interpretations are presented. The presented research allowed a closer look at the mechanisms of processes that are very common in the automotive and chemical industries. Based on theoretical modelling, it was possible to propose the most efficient catalyst that could find potential application in industry–this is the FAU catalyst with a Cu-O-Fe bimetallic dimer with a hydrated copper centre. The essential result of our research is the improvement in the energetics of the reaction mechanism by the presence of an OH group, which will influence the way NO and NH3 molecules react with each other in the deNOx process depending on the industrial conditions of the process. Our theoretical results suggest also how to proceed with the dosage of NO and N2O during the industrial process to increase the desired reaction effect. Full article
(This article belongs to the Section Computational and Theoretical Chemistry)
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