Browse Topic: Catalysts

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Biofuel Effect on Regeneration Capability and Soot Reactivity in SCRoF Systems2026-01-07507/1/2026
Biodiesel blends (B7, B20, B100) were evaluated in a Stage V-compliant SCR on Filter (SCRoF) system for heavy-duty applications to quantify soot reactivity and filter regeneration capability. Compared to conventional diesel (B7), B20 showed slightly faster regeneration performance under real-driving conditions, while B100 resulted in reduced particulate formation and higher soot reactivity, with more intense exothermic events requiring careful management. These differences are attributed to the distinct physical-chemical properties of the fuels (oxygen content, lower heating value) and their interaction with Diesel Oxidation Catalyst (DOC)/SCRoF. All tests were conducted on an engine dynamometer with a Cursor 9 FPT (Fiat Powertrain). Findings are discussed in the context of EU Stage V limits and practical control strategies for heavy-duty applications.
Costa, Simone
Advanced Alloys for Rotorcraft Enabled by ICME (Presentation Only)F-0082-2026-03415/5/2026
QuesTek is advancing a suite of emerging alloy technologies to address modern rotorcraft engineering challenges. Current initiatives prioritize the optimization of "print-to-use" materials, such as 17-4PH and other specialized steels designed to minimize or eliminate post-processing requirements in additive manufacturing. These innovations represent a strategic shift toward materials that are not only high-performing but are also specifically tailored for next-generation manufacturing workflows. The catalyst for these advancements is QuesTek’s mastery of Integrated Computational Materials Engineering (ICME). These core capabilities are now deployed through QuesTek's ICMD® software platform, which empowers engineering teams with predictive simulation tools that eliminate the bottlenecks of traditional trial-and-error methodologies. By integrating these physics-based models into a centralized digital environment, QuesTek enables the rotorcraft industry to design, test, and implement advanced materials with unprecedented speed, reduced costs, and increased technical confidence.
Sebastian, Jason, Gaffey, Michael, Kozmel, Thomas
Experimental and Kinetic Modeling Study of Aged Natural Gas Three-Way Catalyst Performance2026-01-03734/7/2026
The applicability of three-way catalyst (TWC) models for system-level aftertreatment simulations under transient operating conditions of natural gas engines depend on accurate integration of reaction kinetics as a function of the air-fuel equivalence ratio lambda(λ). A comprehensive global kinetic model has been developed for an aged commercial three-way catalyst (TWC), incorporating key reaction pathways including oxidation of CO, CH₄, C₂H₆, and H₂; reforming of CH₄ and C₂H₆; the water-gas shift reaction; and NO reduction via CO and H₂. The model also accounts for oxygen storage capacity (OSC) and its dynamic interaction with CO and H₂. To calibrate kinetic parameters, systematic bench-scale flow reactor experiments were conducted under lean, stoichiometric, and rich conditions. Performance metrics focused on CH₄ and C₂H₆ oxidation and reforming across varying O₂ and CO concentrations, and NO reduction with CO and H₂ under different oxygen levels. Experimental results revealed that CO suppresses the reforming of CH₄ and C₂H₆. NO conversion was observed between 150°C and 600°C, with H₂-driven reduction producing NH₃, N₂, and N₂O depending on lambda (λ). Under rich conditions, complete NO conversion occurred from 150°C, while lean conditions showed reduced NO conversion at elevated temperatures due to H₂ oxidation. NO reduction with CO initiated at 250°C, achieving full conversion under rich conditions. The model accurately captures the influence of λ on NO reduction with both H₂ and CO, predicts NH₃ formation under rich conditions, and simulates H₂ generation via the water-gas shift reaction above 400°C. It successfully reproduces λ sweep data (λ = 0.95–1.02) and demonstrates CO inhibition effects on H₂ oxidation and NO reduction. This global model is validated with dithering reactor data and qualitatively captures key trends in data which aids in catalyst sizing, calibration robustness and the system level modeling of end of useful life parts. Further validation of the current developed model with lean-rich cycle tests confirms the model’s ability to predict NOx slip at the onset of rich cycles impacting the ability to accurately predict NOx emissions during engine braking events in system level models.
Raj, Richa, Kim, Mi-Young, Aigbiremolen, Grace, Srinivasan, Anand
Simultaneous Reduction of NOx and Fuel Consumption for Off-Road Powertrains2026-01-02964/7/2026
Simultaneously reducing criteria pollutants and fuel consumption is important for clean air and improving vehicle total cost of ownership. The goal of this effort was focused on a 90% NOx reduction and 10% fuel savings for an off-road 407 kW diesel engine. The baseline was a production Fiat Powertrain 13L engine and aftertreatment system meeting 0.4 g/kW-hr NOx. The baseline system was quantified over the NRTC, RMC, new low load cycle and five field cycles. A next generation engine was built incorporating several fuel-efficient design features, including a higher compression ratio, increased fuel-rail pressure, low-friction piston rings, and a high-efficiency variable-geometry turbocharger. Cylinder deactivation and EGR pump technologies were added to this engine as well. The combination was optimized prior to adding advanced aftertreatment systems, showing the trade-off of engine out NOx and exhaust temperature. Two next-generation catalyst technologies were employed into a LO-SCR plus main SCR system, both with and without an electric heater upstream of the LO-SCR. These catalysts were hydrothermally aged to simulate significant field use. Dual SCR dosing with newly developed controls played a critical role in achieving the proper split between the upstream LO-SCR and the downstream main SCR. Adding a next generation mixer for the downstream SCR proved essential in obtaining the final results. The optimal configuration required adding an electric heater to elevate the exhaust temperature at the LO-SCR for early cycle NOx reduction. The final results showed a 94.8% NOx reduction and 15.7% fuel savings on the composite NRTC.
McCarthy, Jr.,, James, Wine, Jonathan, Bradley, Ryan, Hasseman, Andy, Prikhodko, Vitaly, Howell, Thomas
CuSCR Catalysts Under H 2 -ICE Exhaust Gas Conditions2026-01-03614/7/2026
In the near to mid-term, hydrogen internal combustion engines (H2-ICE) can be a bridge technology for reducing carbon emissions. A few challenges anticipated under lean-burn H2-ICE operation are the significant drop in turbo-out temperatures, combined with higher water content, and the possible presence of unburned hydrogen in the exhaust, which could have a potential impact on performance and durability of the downstream exhaust aftertreatment system, particularly oxidation and SCR catalysts, as these conditions can suppress low-temperature oxidation activity, perturb Cu-site speciation and redox cycling in SCR catalysts, and exacerbate hydrothermal aging under sustained wet operation. This study examines the impact of excess water and residual hydrogen on Cu-SCR durability, active site chemistry, and stability for the case with and without an upstream oxidation catalyst, through aging tests at 450 °C and 550 °C. Changes in Cu redox cycles were assessed through site quantification using multiple titration techniques to determine the influence of excess H2O and H2 on catalyst performance and aging.
Kim, Mi-Young, Daya, Rohil, Kamasamudram, Krishna
Impact of Hydrogen on Methane and Pollutant Emissions over Three-Way Catalysts with Natural Gas–Hydrogen Blends2026-01-03574/7/2026
Blending natural gas (NG) with hydrogen (H₂) can improve combustion and engine performance while potentially facilitating the catalytic conversion of methane and other pollutants, resulting in cleaner tailpipe emissions. This study evaluates the impact of H2 on the conversion of methane, CO, and NOx emissions on a commercial three-way catalyst (TWC) in a flow reactor using synthetic gas mixtures that simulate stoichiometric engine exhausts with NG or NG+H₂ combustion. The work examines whether, and how, the additional amount of H₂ in the exhaust stream affects the conversion efficiency of methane and other pollutants. Experiments were conducted with both degreened and aged catalysts under controlled conditions, systematically varying temperature, the air-to-fuel equivalence ratio (λ), and λ modulation. Test conditions covered λ values from 0.996 to 1.000 to represent nominally stoichiometric engine operation with different λ modulation amplitudes, as well as a range of temperatures to inform control strategies for effective CH₄, CO, and NOₓ reduction. Overall, the results show that hydrogen addition significantly improves the conversion efficiency of CH₄ and NOₓ, particularly at temperatures below 500 °C. More significantly, this study highlights that exhaust gas composition, operating temperature, λ management, and the oxygen storage capacity of the TWC all play major roles in affecting the tailpipe emissions from NG and NG+H₂ combustion.
Prikhodko, Vitaly, Wang, Min, Park, Yeonshil, Chen, Hai-Ying, Pihl, Josh
Study on the Regulation of the Three-Phase Microenvironment in Low-Platinum MEA2026-01-04434/7/2026
With the growth of energy demand, fuel cells as efficient and clean energy devices, have attracted increasing attention. However, the high cost of membrane electrode assembly (MEA) restricts their large-scale application. Therefore, reducing the platinum usage and improving performance have become key research point. In this work, MEA was prepared and excellent performance of 1.52 W·cm-2 was achieved at a low platinum loading. The influence of different ionomer/carbon (I/C) ratio on the performance of fuel cells was systematically investigated. It was found that the performance of the MEA was the highest when the I/C ratio is 0.6. Quantifying hydrophilic and hydrophobic characteristics of catalyst layers with varying ionomer contents revealed that the proton conduction efficiency is optimal when the I/C ratio is 0.6. This balance established efficient proton conduction pathways, from the results of proton conduction impedance testing. SEM analysis demonstrated that pore structure integrity was compromised at non-optimal I/C ratios, exhibiting pore blockage or cracking. The CV test results confirmed that the electrochemical active surface area (ECSA) reaches a maximum of 40 m2gPt-1 when the I/C ratio is controlled at 0.6. And the EIS tests indicated that the lowest charge transfer impedance. Combined the physical and electrochemical characterization results with I-V curves, it was clear that the proper ratio of the low I/C region benefits the mass transfer and proton conductions. This study provides theoretical and technical support for performance enhancement and has the potential for the large-scale application of low-platinum MEA in fuel cells in the future.
Li, Xin, Cai, Xin, Lin, Rui
Comparison of Ammonia Emission Characteristics Between Different Gasoline Vehicles Equipped with Three-Way Catalysts2026-01-03744/7/2026
In recent years, the tightening of vehicle emission regulations has led to a decreasing trend in regulated pollutants such as NOₓ and CO. However, the emission of ammonia (NH₃), which is unintentionally generated during the purification process in three-way catalyst of gasoline vehicles, has become a growing concern. NH₃ emissions from vehicles can serve as a precursor to PM2.5 and have been reported to cause local roadside pollution. Therefore, there is a growing need for on-road testing to identify conditions under which NH₃ is likely to be emitted. Furthermore, since engine control strategies vary among vehicle types, it is desirable to consider differences in emission behavior across different models. In this study, on-road NH₃ emissions were measured for multiple vehicle models with different powertrains, and the effects of engine behaviors and engine operating duration across vehicles on NH₃ emissions were investigated. To analyze differences in NH₃ emission behavior among vehicle types, conventional gasoline vehicles and series-type hybrid vehicles were employed. Additionally, vehicle control parameters were obtained via an OBD (On-Board Diagnostics) interface unit and utilized for analysis. The analysis revealed that, for the conventional gasoline vehicles, aggressive accelerator pedal control induced rapid fluctuations in engine speed, which in turn led to NH₃ emissions. In contrast, for the series-type hybrid vehicles, NH₃ emissions were primarily observed when the engine started under specific conditions, whereas differences in driver behavior had only a minor direct impact on NH₃ emissions. In addition, longer engine operating durations resulted in higher emission levels. A common characteristic observed across both vehicle types was that NH₃ emissions were elevated during periods corresponding to CO emissions, which serve as precursors to NH₃ formation.
Ashizawa, Keigo, Fukunaga, Chisato, Gao, Tianyi, Sato, Susumu
Experimental Evaluation of After-Treatment Solutions for Heavy-Duty Natural Gas Vehicles to Meet Future CNVII Regulations2026-01-03764/7/2026
The heavy-duty truck market in China has seen a significant increase in the adoption of natural gas-powered engines over the past two years. Simultaneously, the anticipated release of the China VII emissions regulation proposal by the end of 2025 is expected to impose stricter emissions limits on all heavy-duty engines, including new particulate number (PN10) thresholds analogous to those in the Euro 7 regulation. While tailpipe oxides of nitrogen (NOx) and methane (CH4) emissions from natural gas engines can be mitigated through tighter lambda control and adjustments to catalyst volume and precious metal (PGM) loading, addressing NOx and particulate number (PN) emissions necessitate more advanced after-treatment solutions. Although natural gas combustion is virtually soot-free, the entrainment of lubricating oil into the combustion chamber, especially during cold-start conditions, poses a challenge, leading to potential exceedance of the proposed future China VII limits. Additionally, PN emissions from natural gas vehicles are highly dependent on duty-cycles and the state of the actual engine, with applications involving frequent stop/go operation experiencing increased piston ring wear, and thus, higher oil consumption, and elevated PN emissions. This study aimed to evaluate the performance of different after-treatment solutions for natural gas engines in meeting future China VII emissions standards, with a particular focus on the efficacy of particle filters for controlling PN10 emissions. Three different after-treatment configurations, comprising close-coupled and underfloor three-way catalysts, as well as bare and coated filters, were tested on a 15L China VI commercial natural gas engine in a controlled laboratory environment. Emissions and PN10 data were collected over regulatory cold and hot World Harmonized Transient Cycle (WHTC) test cycles, and analyzed for light-off behavior, conversion efficiencies, system pressure drop, and filtration effectiveness for particles as small as 10nm. The relative advantages and challenges of each configuration are discussed. The results indicate that natural gas engines will likely require the integration of particle filter devices to comply with future China VII PN10 limits. The results also show that NOx compliance is challenging and fine-tuning of the lambda calibration is essential for CNVII.
Gao, Jiahui, Besch, Marc, Ding, Ning, He, Suhao, Zhao, Yuxin, Yixiao, Li, Shen, Ye
Effect of Exhaust Gas Components on Oxygen Storage Capacity Measurements of Automotive Catalysts2026-01-03604/7/2026
Three-way catalytic converters (TWC) are one of the most popular methods to help reduce harmful tailpipe emissions emitted from internal combustion (IC) vehicles. To help improve conversion efficiency, TWCs can store and release oxygen via an oxygen storage capacity (OSC) mechanism. During engine control unit (ECU) calibration, on board OSC measurements are correlated to TWC and vehicle emissions to monitor emissions performance throughout the full useful life (FUL) of the vehicle. It is known that different test conditions, including temperature, space velocity and background gases in the exhaust stream affect OSC measurement, potentially altering the calculated OSC values and thus the perceived level of OSC and emissions preformance during operation. This study utilises an OMEGA test bench to complete OSC measurements on the full-scale automotive catalyst samples to quantify the effects of different background gases including carbon monoxide, hydrocarbons and nitric oxide on OSC measurements, concluding that all background gases studied affect measured OSC values. The study revealed that hydrocarbons had the largest effect on OSC measurement increasing OSC values by up to 50%. It was concluded that the increase in OSC measurement with injected hydrocarbons was due to the breakdown of hydrocarbons on the catalyst surface during rich periods of operation increasing the amount of oxygen required to fully oxidise the catalyst resulting in a larger perceived OSC measurement. During the initial ECU calibration original equipment manufacturers (OEM) should consider these effects on OSC measurement and understand how this will affect perceived OSC and vehicle emissions performance for FUL and onboard diagnostics (OBD) applications. This will help ensure emissions compliance and guide optimized catalyst and engine calibrations.
Mc Grane, Liam, Douglas, Roy, Irwin, Kurtis, Woods, Andrew, Elliott, Matthew, Istrate, Oana, Nockemann, Peter
New Graphite-Based Catalyst in Biodiesel Production04-19-02-00093/20/2026
Climate change and the depletion of fossil fuels have increased the need for renewable energy sources such as biodiesel. Biodiesel is an environmentally friendly fuel derived from various vegetable oils through a process known as transesterification. In this study, a new graphite-based heterogeneous catalyst was developed by modifying it Na2CO3, K2CO3, Al2O3 and was used for biodiesel production from linseed, cottonseed, sunflower, olive oils. Catalyst activity gradually decreased from 90.0 to 76.7% for cottonseed oil, from 93.0 to 76.0% for olive oil, from 95.0 to 77.0% for sunflower oil, and from 89.0 to 69.0% for linseed oil after the fourth operation. The fuel properties of the obtained biodiesel samples were investigated and the most favorable characteristics of cottonseed oil–based biodiesel were found to be d 4 20 = 0.8448, ν 40 = 3.3820, flash point of 93°C. Based on the X-ray broad peaks at 22.8° and 26.4°, we can note that after the four-time reaction cycle, the structure of the catalyst was destroyed to expanded and pure graphite with the loss of catalytic activity. Additionally, the influence of the amount of oleic, linoleic, linolenic, and saturated acyl groups in oil samples on exploitation properties was investigated by NMR spectroscopy.
Mamedov, Ibrahim, Mamedova, Gulben, Mamedova, Yegana
Optimization of Combustion Stability and Fuel Economy for Dedicated Hybrid Engines with High Exhaust Gas Recirculation Rate03-19-02-00082/26/2026
In recent years, the rapid growth of hybrid vehicles has driven the development of dedicated hybrid engines (DHEs) as a key powertrain technology for achieving high thermal efficiency and low emissions. Driven by stringent emissions regulations and demand for improved fuel economy, enhancing thermal efficiency in gasoline engines remains a critical industry challenge. Exhaust gas recirculation (EGR) technology dilutes oxygen in the intake charge, suppresses knock, and optimizes combustion phasing. However, excessive EGR rates compromise combustion stability by inducing elevated cyclic variability and potential misfire, posing challenges in maintaining stable combustion and improving fuel efficiency at high EGR levels. Thus, combustion stability and fuel efficiency optimization in Geely’s DHEs under high EGR conditions was investigated in this article. In this study, a high tumble combustion system was designed to enhance charge motion and promote stable flame propagation. Furthermore, exhaust gases were drawn from the upstream side of the three-way catalyst to realize high EGR rate. Additionally, high-energy ignition system was applied to ensure stable combustion under high EGR dilution conditions. Compared with the 1.5T engine with a similar technical route, the optimized DHE achieved a 5.4% increase in EGR rate and a 7.2 g/kWh reduction in brake specific fuel consumption (BSFC). These results demonstrate the feasibility of high EGR operation in gasoline engines through synergistic combustion system design and ignition enhancement, offering a scalable solution for meeting future fuel efficiency and emissions targets.
Li, Qiang, Deng, Xiaorong, Ren, Siming, Zhang, Peiyi, Zhu, Yunfeng, Li, Hongzhou, Yan, Pingtao, Gu, Xiangsheng
Alternate Catalyst for DOC in a Catalytic Converter2026-28-00162/12/2026
Emission norms have become much more stringent to reduce emissions from vehicles. Diesel engines in particular are the predominant contributors to higher emissions. Diesel Oxidation Catalyst (DOC) in diesel engine catalytic converter systems is the crucial component in reducing harmful emissions such as Carbon Monoxide (CO) and unburnt Hydrocarbons (HC). DOCs often rely on expensive noble metals like platinum, palladium, and rhodium as catalyst materials. This significantly raises the cost of emission control units. The proposed idea is to explore MnO2-CeO₂ (Manganese Oxide, Cerium Oxide) as an alternative catalyst to traditional DOC materials. The goal is to deliver effective oxidation performance while reducing overall system cost. MnO2-CeO₂ catalysts are promising because of their good low-temperature activity, oxygen storage capacity, and redox behavior. These features are helpful for diesel engines that operate under various conditions. They improve the oxidation of CO and HC, even during cold starts or at lower exhaust temperatures. The catalyst was successfully synthesized and applied to a honeycomb substrate, resulting in a fabricated catalytic converter prototype. Quantitatively, the fabricated MnO₂–CeO₂ coated prototype demonstrated a 43% reduction in CO, 47% reduction in HC, 27% reduction in NOx, and 41% reduction in PM during low-temperature exhaust testing (150 – 400 °C) during testing on a 1.5 L diesel engine. The results were based on repeated experimental runs using an uncoated substrate as baseline. The work also focuses on material accessibility and environmental sustainability by using non-noble, widely available metal oxides. The hypothesis of this study is that a MnO₂–CeO₂ catalyst synthesized via co-precipitation can deliver meaningful low-temperature oxidation performance at significantly lower cost compared to PGM-based DOCs. Thus, the project contributes a significant step toward developing more accessible and sustainable emission control technologies for the automotive industry.
C, Jegadheesan, T, Karthi, Rajendran, Pawan, Muruganantham, Kowshiik, S, Vaitheeshwaran
New Material Significantly Enhances Green Hydrogen Production EfficiencyTBMG-545612/1/2026
Green hydrogen, produced through water electrolysis, is a next-generation eco-friendly energy source as it does not generate pollutants like carbon dioxide during production. Catalysts play a crucial role in the water electrolysis process, splitting water into hydrogen and oxygen. The efficiency of green hydrogen production largely depends on the performance of these catalysts. Therefore, the commercialization of green hydrogen hinges on the development of cost-effective catalysts capable of maintaining high performance over extended periods.
All New 1.2L Turbocharged Gasoline Direct Injection Engine from Tata Motors2026-26-00711/16/2026
There is continuous push from the legislation for stringent fuel economy and emission regulations while the modern customers are demanding more engaging driving experience in terms of performance and refinement. To meet this Tata Motors has developed an advanced 1.2L 3-cylinder turbocharged gasoline direct injection engine. This next-generation powertrain delivers optimum efficiency, reduced emissions, superior performance with refined NVH characteristics. The key features used to enable these demanding requirements includes a 35 MPa fuel injection system, Miller Cycle operation and electrically actuated variable nozzel turbocharger (VNT). A uniquely designed BSVI complaint (WLTP ready) exhaust after-treatment system with Four-Way Conversion Catalyst (FWC+TM) ensures optimum emission control. A centrally mounted variable cam phaser minimizes pumping losses. The lightweight yet rigid all-aluminum engine structure, featuring an integrated structural oil sump, enhances durability and stiffness. These technology packages coupled with right engine management system results in over 15 % better brake thermal efficiency (BTE) and 24% higher low end torque as compared to its predecessor 1.2L TC MPFI engine. The engine delivers 208 Nm/l transient torque density and 225 Nm of Maximum Torque along with 125ps Maximum Power. This paper details the engine’s layout, combustion system optimizations and comparative studies on injector selection, fuel spray patterns for achieving right performance, emissions and NVH.
Hosur, Viswanatha, Ghadge, Ganesh Narayan, Joshi, Manoj, Jadhav, Aashish, Panwar, Anupam
CS Structure: New Metallic Catalyst Substrate Generation for 2- and 3-Wheeler Applications2026-26-02201/16/2026
Affordable, efficient and durable catalytic converters for the two and three-wheeler industry in developing countries are required to reduce vehicle emissions and to maintain them at a low level; and therefore, to participate in a cleaner and healthier environment. Especially, metallic catalyst substrates developed by Emitec Technologies GmbH with structured foils like the Longitudinal Structure (LS), or LS-Design® are fully compatible to this effort with more than 70% share of produced 2/3 Wheelers metallic catalyst substrates for the Indian market in 2024. One decade after the market introduction of this LS structure, Emitec Technologies GmbH will introduce now a new generation of foil structure: the Crossversal Structure (CS) or CS-Design®, that improves further the affordability, the efficiency of metallic catalytic converters, keeping the durability at same level as previous substrate generation. The paper will briefly review the development of metallic substrates for 2/3 wheelers applications, especially the development of structured foil substrates, describe the new foil structure CS, compare its performances to those of previously developed metallic substrates with structured LS foils. For this later purpose, experimental emission measurements under WMTC driving cycle on roller bench will be carried out on one Indian BS6 - OBD2 four stroke motorcycle. The results will be discussed and the benefits of CS for current and future motorcycle applications will be drawn.
Jayat, Francois, Seifert, Sven, Bhalla, Ashish, Ganapathy, Narayana Prakash
A Case Study of Emission Optimization using Machine Learning2026-26-02291/16/2026
The Exhaust Emission Control is a vital part of automotive development aimed at ensuring effective control of pollutants such as NOx, CO, and HC. The traditional method of calibrating emission control strategies is a highly time-consuming process, which requires extensive vehicle testing under a variety of operating conditions. The frequent updates in emission legislation requires a high-efficiency process to achieve a faster time-to-market. The use of Machine Learning (ML) in the domain of emission calibration is the need of the hour to proactively improve the process efficiency and achieve a faster time-to-market. This paper attempts to explores emerging trend of Machine Learning (ML) based data analysis that have improved the overall process efficiency of emission control calibration. The data generated by automated programs could be used directly in data analysis with minimal or no need for data cleaning. The Machine Learning (ML) models could be trained by historical data from relevant engine platforms to predict the output. The integration of Machine Learning (ML) models with automated measurement processes further enhances the process by enabling model-based calibration development. The use of automated programs and machine learning (ML) models could ensure high accuracy of the emission calibration data. This methodology could significantly reduce the need for volumes of measurements required for data analysis and calibration. This could further help in optimized usage of testing facilities, ultimately saving time and resources. A 70% overall savings in time and resources could be expected with the use of automation and machine learning models. This methodology also supports faster calibration development cycles that would be required for adhering to frequent legislative changes and achieving faster time-to-market.
Dhayanidhi, Hukumdeen, Balasubramanian, Karthick, A, Akash
Introducing a New Catalyst Family in Gasoline Aftertreatment2026-26-02311/16/2026
This paper is to introduce a new catalyst family in gasoline aftertreatment. The very well-known three-way catalysts effectively reduce the main emission components resulting from the combustion process in the engine, namely THC, CO, and NOx. The reduction of these harmful emissions is the main goal of emission legislation such as Bharat VI to increase air quality significantly, especially in urban areas. Indeed, it has been shown that under certain operating conditions, three-way catalysts may produce toxic NH3 and the greenhouse gas N2O, which are both very unwanted emissions. In a self-committed approach, OEMs could want to minimize these noxious pollutants, especially if this can be done with no architecture change, namely without additional underfloor catalyst. In most Bharat VI gasoline aftertreatment system architectures, significant amounts of NH3 occur in two phases of vehicle driving: situations with the catalyst temperature below light-off, which appear after cold start or at low-speed urban driving and hot, high mass flow phases. In this paper, we will compare several approaches to reduce NH3 starting with an existing gasoline technology, diesel technologies modified to gasoline conditions and the especially developed novel gasoline Secondary Emission Treatment (SET) catalyst, providing both ammonia abatement and underfloor three-way functionality. SET is the combination addressing both the cold start phase and hot driving conditions. In addition, it fulfills the role of an underfloor three-way catalyst, responsible for CO and NOx hot phase treatment.
Kuhn, Sebastian, Magar, Avinash, Kogel, Julius, Lahousse, Christophe
Biodiesel Production via Homogeneous Route (KOH) and Heterogeneous Route (K 2 O/Nb 2 O 5 )2025-36-011612/18/2025
Biodiesel, a renewable biofuel obtained from vegetable oils or animal fats, has emerged as a sustainable alternative to fossil fuels. This fuel has stood out for its ability to reduce greenhouse gas emissions, helping to mitigate environmental impacts. Biodiesel is produced by reacting oil with an alcohol in the presence of a catalyst, which can be homogeneous or heterogeneous. Heterogeneous catalysis has advantages such as ease of separation, greater tolerance to oils with a high fatty acid content and the possibility of reusing the catalyst, which reduces costs and minimizes waste generation. Among the various heterogeneous catalysts available, niobium-based compounds stand out. The use of niobium-based catalysts is advantageous due to the vast reserves of this element in Brazil, guaranteeing autonomy in production and strengthening the national biofuels industry. This work investigated the production of biodiesel from soybean oil using the homogeneous and heterogeneous transesterification routes. The homogeneous route used 0.7% KOH dissolved in methanol, operating at 60 °C for 1 hour with a methanol:oil molar ratio of 6:1. The heterogeneous route used a solid K2O catalyst supported on Nb2O5, in a ratio of 4% by mass, with a molar ratio of 10:1 and a reaction time of 4 hours. The yield obtained was 85% for the homogeneous route and 90% for the heterogeneous route. The biodiesel from the homogeneous route had a slightly basic pH, requiring neutralization with hydrochloric acid, while the product from the heterogeneous route had a neutral pH, requiring no additional treatment. The results indicate that although the homogeneous route is faster and uses less catalyst, the heterogeneous route has advantages in terms of yield and quality of the final product, as well as less environmental impact. Heterogeneous catalysts such as K2O/Nb2O5 are therefore promising for the sustainable production of biodiesel.
Coelho, Gabriella Vilela, Alvarez, Carlos Eduardo Castilla, Ribeiro, Jessica Oliveira Notório
Accelerated Aging Methodology for Catalyst on Engine Test Benches: Practical Considerations for a Successful Implementation of the Methodology2025-36-008712/18/2025
The durability of automotive catalysts is a critical factor in ensuring compliance with strict environmental regulations throughout the vehicle’s lifespan. Accelerated aging methods are widely used in the industry to predict catalyst degradation over a reduced period, allowing for performance optimization and ensuring their effectiveness in emission reduction. The ABNT NBR 16897:2021 standard establishes general guidelines for these tests but does not define in detail all the experimental conditions necessary for practical implementation. Addressing this gap, this study proposes the application and development of a standardized experimental procedure for accelerated catalyst aging, aligned with current regulations and adapted to test conditions in an engine dynamometer test bench. The objective is to provide a solid technical foundation, filling gaps for future implementations of this methodology, allowing investigations into the durability of aftertreatment systems and assisting both researchers and manufacturers in validating their products. This paper focuses exclusively on the description and validation of the experimental procedure. The methodology adopted in this study involves equipping the catalysts with K-type thermocouples for precise thermal monitoring, the selection and calibration of an internal combustion engine on a dynamometer test bench, and the control of test parameters via the FuelTech control unit. The aging time was determined using the Bench Aging Time (BAT) equation, following the temperature profile recorded during the Standard Road Cycle (SRC) on a chassis dynamometer. The implementation of the cycle, following the collected data, is carried out by running the engine on a bench dynamometer using the Standard Bench Cycle (SBC), ensuring precise accelerated aging that accurately reflects the same thermal exposure that the aftertreatment unit experiences during conventional vehicle operation throughout its lifespan. The methodological standardization and the analysis of implementation challenges offer a solid technical reference for future applications.
Yana, Diego Andree Reynoso, Pradelle, Florian, Braga, Sergio Leal, Sánchez, Fernando Zegarra, Machado, Guilherme Bastos, Carvalho, Rogério Nascimento de, Silva, Katia Moniz da
Investigation of Degradation of Catalyst Performance due to Phosphorus Poisoning in Practical Catalysts2025-32-007311/3/2025
Although exhaust gas regulations for internal combustion engines have been in place for quite some time, they are still getting stricter every year. Motorcycles are no exception. Exhaust gas regulations for after-degradation durability have already been applied, and the next regulation is expected to require vehicles in use in the market to meet the exhaust gas regulation values. Technology to comply with exhaust gas regulations mainly deals with catalyst performance degradation. The main issues are metal sintering and poisoning. In particular, it is difficult to explain clearly the change in catalyst performance due to poisoning alone, as it is necessary to distinguish it from sintering and to determine the distribution of deterioration. However, phosphorus poisoning from oil cannot be ignored unless oil consumption is reduced to zero. In order to understand the change in practical catalyst performance due to poisoning with a distribution of degradation, it is necessary to explain the distribution of poisoning substances and to understand the performance change at each point while separating poisoning and sintering. In this report, we attempt to show the distribution of poisoning substances on the catalyst from individual driving histories based on a simple adsorption mechanism hypothesis. Furthermore, we investigated the performance change at each point of the poisoning substance distribution. To this end, we prepared a catalyst in which it is believed that there was almost no sintering distribution within the catalyst during degradation durability. We investigated samples that were divided as finely as possible in the flow direction. By using the rear end part of the catalyst, which is almost unpoisoned, as a reference, we can obtain the change in catalyst performance relative to the amount of poisoning. These results will be used to consider the performance change of practical catalyst due to poisoning.
Ibara, Takeru, Itou, Shiori, Yusa, Kazuma, Kinoshita, Hisatoshi, Motegi, Takuya
Performance Analysis of a Hydrogen-blended Naturally Aspirated Gas Engine with a Dedicated Exhaust Gas Recirculation System2025-32-004611/3/2025
With the publication of the Renewable Energy Directive (RED) III in 2022, the European Union increased its renewable energy consumption target to 42.5% by 2030. Consequently, gaseous fuels derived from renewable electricity, particularly green hydrogen, are expected to play a pivotal role in the decarbonization of the energy sector. One promising application of green hydrogen is its integration into combined heat and power (CHP) plants, where it can replace natural gas to reduce CO2 emissions. Pure hydrogen as fuel or blended with natural gas has demonstrated potential for lowering both pollutant emissions and fuel consumption while maintaining or even enhancing engine performance. But it is expected, that the amount of available green hydrogen will be limited in the beginning. So new engine systems with hydrogen and natural gas for CHP plants are required, that offer more CO2-benefit and NOx reductioon than from fuel substitution only. In the LeanStoicH2 project, a novel approach was developed to optimize the operation of a four-cylinder stationary gas engine for hydrogen utilization. The project introduced a customized exhaust gas recirculation (EGR) system in which the exhaust gas from a hydrogen-fueled cylinder is fully recirculated into the intake mixture of three other cylinders operating stoichiometrically with natural gas. This configuration leverages the benefits of both lean and stoichiometric combustion strategies. After passing a lower temperature condenser, the dry recirculated exhaust gas, which is CO2- and H2O-free, dilutes the intake mixture of the three cylinders, mimicking lean operation and thus increasing engine efficiency due to the higher isentropic coefficient (κ). Simultaneously, this approach reduces combustion temperatures, thereby lowering knock tendency and engine wear. Furthermore, the stoichiometric operation of the EGR-receiving and emission relevant cylinders allows for the effective use of a three-way catalyst, significantly reducing pollutant emissions. Experimental results confirm that this innovative combustion strategy enhances indicated efficiency from 41.5% to 43.5% compared to series operation, and maintains low NOx tail pipe emissions. These findings highlight the potential of advanced hydrogen combustion strategies to improve the sustainability and performance of gas engine CHP plants, supporting the transition toward a greener energy landscape.
Salim, Naqib, Beltaifa, Youssef, Kettner, Maurice
Reactivity Retention of Modern Converters for Stringent Emission Control2025-01-040110/7/2025
The growing emphasis on environmental protection and sustainability has resulted in increasingly stringent emission regulations for automotive manufacturers, as demonstrated by the upcoming EURO 7 and 2027 EPA standards. Significant advancements in cleaner combustion and effective aftertreatment strategies have been made in recent decades to increase the engine efficiency while abiding by the emission limits. Among the exhaust aftertreatment strategies, three-way catalyst has remained the primary solution for stoichiometric burn engines due to its high conversion efficiency and ability to simultaneously allow both oxidative and reductive reactions in a single stage with spatial separation due to the oxygen storage capabilities of ceria. However, fuel and lubricant-borne sulfur and phosphorus compounds have been shown to have a significant long-term effect on the activity of three-way catalysts, particularly during the lean-rich transitions and oxygen storage processes. In the present study, the impact of sulfur contamination on the conversion efficiency and oxygen storage capacity of the three-way catalyst has been investigated on a heated flow reactor bench platform. The influence of sulfur accumulation on the water-gas shift reaction and activity of ceria has been studied. Additionally, the process of sulfur removal at high temperature (~700-750°C) has also been explored. Relevant engine-out exhaust conditions from the SI engine platform, including flow, temperature, and exhaust species (individually), were replicated on a heated aftertreatment flow bench during contamination and regeneration cycles. A comprehensive analysis of species before and after the catalyst sections was performed using Fourier-transformed infrared (FTIR) and mass spectrometers to study and quantify the conversion and formation of species including sulfur species (sulfur dioxide and hydrogen sulfide) and hydrogen, under different catalyst conditions. The conversion selectivity of sulfur species during regeneration is also investigated. The results show that sulfur contamination causes a substantial reduction in oxygen storage capacity. Effective sulfur removal required a combination of high temperature (~700°C or higher) and lean-rich cycling; absence of either condition resulted in incomplete desulfation and the selectivity towards sulfur dioxide and hydrogen sulfide was largely dependent on the reductant species used during high temperature desulfation.
Sandhu, Navjot Singh, Yu, Xiao, Jiang, Chuankai, Ting, David, Zheng, Ming
Combined Virtual and Experimental Approach to Develop Highly Efficient Metallic Catalyst for New World Wide Emission Legislation2025-24-00809/7/2025
The market penetration of Battery Electric Vehicles (BEV) in Europe is not following the foreseen scenario. This is related to several factors, such as uncertainty of the second-hand value of BEV, real driving range under cold conditions and availability of charging stations. Even if the European Community is still planning a full ban of Internal Combustion Engines (ICE) by 2035, in the rest of the world a more technology neutral approach is being pursued. Car manufacturers are developing different powertrain architectures, from mild- to full-hybrid and Range Extenders (REEX). In this context of different emission regulations, and wide range of powertrain architectures, the focus of the development will be the increase of catalyst efficiency without any big impact on exhaust aftertreatment cost. In previous work [1] the authors have used a 1D simulation approach to support the optimization of metallic TWC substrate for the High Power Cold Start use case. Additionally, a 3D CFD was used to investigate the effect of flow rate peaks where maldistribution appears to have a major impact on the overall abatement efficiency. Additionally, a complete validation of the 3D tool was made using roller bench data, measured by Aurobay on a representative production car. This step served also as an opportunity to deeply validate the tool. The limitation of the heat losses, along with a tailored choice of the thermal mass and properties of the substrate, allowed to guarantee the desired abatement. In this work a comprehensive 3D CFD approach is used to assess the possibility to simulate the efficiency of a metallic substrate during typical emissions cycles. Moreover, a dedicated test, using lambda-step, will be used to assess the response of metallic substrates to lambda perturbation.
Montenegro, Gianluca, Della Torre, Augusto, Marinoni, Andrea, Onorati, Angelo, Klövmark, Henrik, Laurell, Mats, Pace, Lorenzo, Konieczny, Katrin
Water Injection as an Enabling Technology for Stoichiometric High Performance Normally Aspirated Engines2025-24-00279/7/2025
The mainstream automotive market is rapidly transitioning to electrified and fully electric powertrains. Where gasoline engines are still employed, they are frequently turbocharged units with relatively low maximum engine speed and modest power density. The hypercar class, in contrast, has recently seen somewhat of a renaissance in high performance, high speed, naturally aspirated gasoline engines, which are prized for their emotional contribution to the vehicle. In order to guarantee high conversion efficiency of a Three Way Catalyst in the exhaust system, an engine must be operated at stoichiometric air-fuel ratio. At high power density, this may result in very high exhaust gas temperature, which poses a risk to engine and vehicle hardware. A number of technological interventions to extend the maximum stoichiometric performance whilst respecting component limitations have already been described in the literature, but many of these are not applicable to specific engine architectures in the hypercar niche. This work describes some of the unique challenges for such vehicle types in achieving stoichiometric operation in all conditions and identifies water injection as a key enabling technology. An experimental campaign on a high speed normally aspirated mule engine with water injectors installed in the intake ports is described. This is supported by Computational Fluid Dynamics calculations with detailed chemistry and bench testing of the injectors using Phase Doppler Anemometry and momentum flux techniques. It is shown that stoichiometry can be maintained at peak power, but some further complementary technologies may be of interest to limit water consumption and ensure an adequate combustion stability.
Corrigan, Dáire James, Villa, Davide, Penazzi, Eugenio, Meghani, Amit, Knop, Vincent, Caroli, Giacomo, Frigeri, Davide, Ruggiero, Federico, Malaguti, Simone, Postrioti, Lucio, Maka, Cristian
Investigation of a Lambda Leap Strategy for Hydrogen Internal Combustion Engines to Balance Efficiency with Performance and Vehicle Packaging2025-24-00709/7/2025
The paper reports an investigation into employing a “lambda leap” (λ leap) strategy for hydrogen internal combustion engines (H₂ICEs), wherein inherently low emissions of oxides of nitrogen (NOx) are afforded at light load via operation at lambda 2.5, and at higher load by operation at stoichiometry utilizing a three-way catalyst (TWC) for NOx control. This approach means it is necessary under transient operation to “leap” between high values of lambda and stoichiometry from one cycle to the next, in order to avoid completely the λ ≈ 1.3 area where high combustion NOx is generated away from lambda equal to 1; this is because lean catalysis of NOx will be extremely challenging at the rate that it is generated there. To achieve this, a short cam profile was introduced to reduce air mass flow by 57.5%, enabling this leap without changing the fuel injection amount, while preserving favorable combustion characteristics via an early Miller cycle. The study models a 2.0 L inline four-cylinder turbocharged engine converted to hydrogen operation and equipped with the necessary valvetrain functionality. Engine maps show that the λLeap strategy increases peak brake efficiency to 38.6% and positions the high-efficiency region in a more usable part of the operating range of the engine. Vehicle-level simulations across three driving cycles (NEDC, WLTP, FTP75) and three vehicle classes (sedan, medium SUV, large SUV) show fuel consumption reductions of up to 9.9% and engine-out NOx reductions exceeding 50% compared to stoichiometric-only operation. The paper also explains why the strategy would be especially beneficial for light-duty H₂ICEs, given that they have different operating areas compared to heavy-duty ones, and why vehicle packaging, mass, and drag advantages would accrue as well. Finally, some discussion is made regarding how H₂ICEs might benefit from upsizing of their swept volumes if this strategy is successfully employed.
Fong Cisneros, Eric J., Kodaboina, Raghu Vamsi, Vorraro, Giovanni, Turner, James W. G.
Development of After-Treatment Systems and Control Strategy for a Hybrid-Dedicated Homogeneous Lean Burn Engine2025-01-02176/16/2025
The development of lean-burn gasoline engines has continued due to their significant improvements in thermal efficiency. However, challenges associated with NOx emissions have hindered their mainstream adoption. As a result, the development of an effective NOx after-treatment system has become a key focus in lean-burn engine research. Additionally, HC emissions pose another challenge, as they tend to increase under lean combustion conditions while their conversion efficiency simultaneously declines. This study presents a novel after-treatment system incorporating a lean NOx trap(LNT) and a passive SCR(pSCR) system. This configuration enables efficient NOx reduction at a competitive cost while maintaining operational simplicity. Moreover, conventional catalyst technologies, including three-way catalysts (TWCs) and fuel-cut NOx traps (FCNTs), were optimized to maximize conversion performance under lean operating conditions. To further enhance system performance, various control strategies were explored, including advanced temperature management of after-treatment systems, the regeneration strategy of LNT, and optimized catalyst purge strategies during the cold-start phase. The proposed after-treatment system and control strategies were validated through vehicle testing on a chassis dynamometer. The results demonstrated that a hybrid vehicle equipped with a lean-burn gasoline engine and new after-treatment system can achieve a 10% improvement in fuel efficiency while remaining compliant with future emission regulations, underscoring its viability for real-world applications.
Oh, Heechang, Lee, Jonghyeok, Sim, Kiseon, Lim, SeungSoo, Park, Jongil, Park, Minkyu, Kang, Hyunjin, Han, Donghee, Lee, Kwiyeon, Song, Jinwoo
Impact of Reduced Catalytic Activity on Passive Regeneration of Catalyzed Diesel Particulate Filters2025-01-01856/16/2025
Oxidation catalysts can greatly improve the regeneration efficiency of diesel particulate filters (DPF) by providing sufficient levels of NO2 for low-temperature soot oxidation. As for other automotive catalysts, catalyzed DPFs are subject to aging effects, resulting in decreased performance of the NO oxidation reaction. The life span of DPFs generally only considers the elevated back pressure as a consequence of the accumulation of ash. However, with reduced catalytic activity and impaired functionality of the regeneration process there is a risk of premature replacement of the catalyzed DPF or accumulation of soot above critical levels. In this study, a new exhaust aftertreatment system has been developed to accommodate laboratory-scale catalysts and DPFs for testing with full-size heavy-duty engines. The modified exhaust aftertreatment set-up was used together with a rig for accelerated soot and ash loading to assess the impact of catalyst aging on regeneration performance under real conditions. Experiments were conducted with and without diesel oxidation catalyst to limit or increase the concentration of NO2. It could be demonstrated that the impaired catalytic activity can have a significant impact on the regeneration process. With a limited upstream concentration of NO2 fed to the catalyzed DPF, a temperature increase from about 390 °C to 450 °C was required to initiate the oxidation of soot. Furthermore, an overall lower oxidation rate was observed. With the addition of a diesel oxidation catalyst, resulting in elevated upstream concentrations of NO2, the effect of aging could be partially mitigated leading to more comparable soot oxidation rates with a temperature difference of 30 °C for soot ignition. These results highlight the importance of the catalytic activity for the functionality of the system, which should be considered for future catalyzed DPF design and regeneration strategies.
af Ugglas, Samuel, Finker, Pascal, Ersson, Anders, Yao, Dawei, Pettersson, Lars J., Kusar, Henrik
Effect of Ignition Condition and Fuel Octane Number on Knock Intensity in a Small 2-Stroke Engine2025-01-02116/16/2025
Internal combustion engines (ICEs) remain widely used in automotive transportation for their high energy storage system efficiency and economic benefits. The 4-stroke engine has dominated all other forms to date, because the Otto cycle is relatively simple to understand. However, the significant benefits such as less pumping work and friction, lighter construction of 2-stroke engine, are attractive for applications that prioritize the simplicity and power density as well as meet the emission regulations. The disadvantages of the 2-stroke engine are mainly caused by the lack of sufficient scavenging process. Also, the overlap of the intake and exhaust phases results in charge short-circuiting, more fuel consumption and high unburned hydrocarbon emissions. For these reasons, it is difficult for 2-stroke engines to achieve stoichiometric combustion, making them incompatible with three-way catalyst to control emissions. The residual exhaust gas in the cylinder makes the spark ignition application leads to incomplete combustion and a higher coefficient of variation. Hence, it is imperative to investigate the effect of spark ignition strategies (ignition position, ignition timing conditions) on a portable small 2-stroke engine with complex in-cylinder gas flow distribution. In this study, we discussed the effect of spark ignition strategies on a small 2-stroke engine. In-cylinder combustion characteristics, emission characteristics and flame propagation process were observed by an optical 2-stroke engine with loop-scavenging. Additionally, in terms of fuel properties, gasoline, dimethyl carbonate/gasoline blend fuel and primary reference fuel are used to investigate the influence of ignition method on knock intensity with different octane numbers. To analyze the effect of fuel properties on combustion characteristics, the computational fluid dynamic (CFD) simulation using CONVERGE were conducted to predict the flame propagations. Through the experimental and CFD results, the potential for combustion improvement on 2-stroke spark ignition engine was evaluated by the optimization of ignition strategies.
Liu, Jinru, Yamazaki, Yoshiaki, Otaki, Yusuke, Kato, Hayato, Yokota, Takumi, Iijima, Akira
A Successful Catalyst Design for Advanced Zinc-Iodine BatteriesTBMG-532066/1/2025
Aqueous zinc-ion batteries (ZIBs) have attracted extensive attention due to their high safety, abundant reserves, and environmental friendliness. Iodine with high abundance in seawater (55 μg L-1) is highly promising for fabricating zinc-iodine batteries due to its high theoretical capacity (211 mAh g-1) and appropriate redox potential (0.54V). However, the low electrical conductivity of iodine hinders the redox conversion for an efficient energy storage process with zinc. Additionally, the formed soluble polyiodides are prone to migrate to the Zn anode, leading to capacity degradation and Zn corrosion.
Influence of Exhaust Gas Recirculation on Knock in a Spark Ignition Engine Fueled with Ethanol–Gasoline Blends03-18-03-00194/28/2025
Exhaust gas recirculation (EGR) is widely used in spark ignition engines to reduce throttling losses, decrease exhaust gas temperatures, increase efficiency, and suppress knock. However, the effectiveness of EGR as a knock suppressor is dependent on the fuel type and operating condition. In this study, the effectiveness of EGR to suppress knock was tested with E10, E30, E50, E75, and E100 at a moderately boosted condition. It was found that EGR was effective at suppressing knock with E10, but high EGR rates were required to achieve a knock suppression effect with E30 and E50. No knock suppression effect was observed with E75 and E100 across all tested EGR rates. With E30 and E50, EGR that was passed through a three-way catalyst was more effective at suppressing knock at all EGR rates. Chemkin modeling with neat ethanol revealed that nitric oxide enhanced ignition by increasing the hydroxyl radical concentration in the end gas, resulting in earlier auto-ignition. Directly seeding nitric oxide in the intake system with neat ethanol resulted in an increase in knock intensity, which required a knock-limited CA50 retard of 3.5 crank angle degrees with 660 ppm of nitric oxide.
Gandolfo, John, Gainey, Brian, Lawler, Benjamin
Experimental Study on Thermo-Catalytic Ammonia Decomposition into Hydrogen2024-32-01184/18/2025
In order to rapidly achieve the goal of global net-zero carbon emissions, ammonia (NH3) has been deemed as a potential alternative fuel, and reforming partial ammonia to hydrogen using engine exhaust waste heat is a promising technology which can improve the combustion performance and reduce the emission of ammonia-fueled engines. However, so far, comprehensive research on the correlation between the reforming characteristic for accessible engineering applications of ammonia catalytic decomposition is not abundant. Moreover, relevant experimental studies are far from sufficient. In this paper, we conducted the experiments of catalytic decomposition of ammonia into hydrogen based on a fixed-bed reactor with Ru-Al2O3 catalysts to study the effects of reaction temperature, gas hour space velocity (GHSV) and reaction pressure on the decomposition characteristics. At the same time, energy flow analysis was carried out to explore the effects of various reaction conditions on system efficiency. The results show that both the ammonia catalytic conversion and decomposition efficiency increase with the reaction temperature increasing. However, these two parameters decrease with the increases of GHSV and reaction pressure, the former due to the reduction of ammonia retention time in the reactor as GHSV accelerates, and the latter due to the high-pressure environment inhibiting the overall reaction towards ammonia decomposition. In addition, the maximum conversion rate of 86% and a peak decomposition efficiency of 112% were achieved at 853 K, 2000 h-1, and 0.1 MPa. The energy flow analysis shows that increasing the reaction temperature increases the decomposition losses, but the total calorific value of the reformate increases, which is expected to improve the combustion efficiency of ammonia fueled engines and reduce the unburned ammonia emissions. Furthermore, GHSV has a negligible impact on decomposition losses. This paper contributes to the database of hydrogen production from the ammonia thermo-catalytic decomposition, analyze the energy flow distribution of the catalytic decomposition process, and provides important information for development of zero-carbon ammonia-hydrogen fueled engines.
Li, Ze, Li, Tie, Chen, Run, Li, Shiyan, Zhou, Xinyi, Wang, Ning
Development of NOx Storage Catalyst and Investigation of Deterioration Mechanism for Small Powertrains2024-32-00974/18/2025
In response to the evolving landscape of exhaust gas regulations for small powertrains, reducing NOx emission is increasingly important. This study deeply investigated the feasibility of a NOx storage catalyst (NSC) containing cerium oxide (CeO2) and barium oxide (BaO) for reducing NOx emission. The key functions, NOx storage and reduction performances were evaluated, and deterioration mechanisms were explored through performance evaluations and physical property analyses. The findings revealed a strong correlation between the size of CeO2 crystals and NOx storage performance at low temperature, such as those encountered during city driving conditions. Conversely, at high temperature, such as those during highway driving conditions, NOx storage performance correlated well with sulfur deposition, suggesting that the formation of barium sulfate (BaSO4) contributes to the deactivation. This experiment also showed a strong correlation between NOx reduction performance and BaSO4 formation. A new aging method that can simulate both thermal and sulfur deterioration was established based on these findings. This method effectively reflects field aging conditions. A new NSC based on the concept of resisting this newly established aging method showed significantly improved performance in both NOx storage and reduction. Despite an increase in the amount of barium components compared to the conventional NSC, high performance was maintained after sulfur poisoning. In the case of the new NSC, it was found that weakly basic chemical introduced as a sulfur scavenger suppresses the formation of BaSO4. This new NSC concept is expected to be leveraged in a wide range of vehicles including small powertrains, to achieve robust performance.
Nakano, Fumiya, Koito, Yusuke
Investigation on Degradation Process of PdRuIr/CZ “Pseudo-Rh” Catalysts Used for Motorcycles2024-32-00164/18/2025
Platinum (Pt), palladium (Pd), and rhodium (Rh) are used as active substances in exhaust gas purification catalysts for automobiles. Among these, Rh is an essential element because it efficiently promotes a NOx reduction reaction. On the other hand, the price of Rh has been rising in recent years. From the perspective of the supply risk of rare resources, there is an urgent need to develop technologies to replace or reduce the amount of Rh used in catalysts. We focused on the pseudo-rhodium alloy developed by the ACCEL program of the Japan Science and Technology Agency (JST), and then investigated the application of the pseudo-rhodium alloy on the catalysts of our motorcycles and also the degradation process. A nanosized PdRuIr alloy supported on a ceria-zirconia solid solution (PdRuIr/CZ) was prepared and assembled into a motorcycle for emissions measurement. The PdRuIr/CZ catalyst with an alloy loading of 4.0 g/L had initial properties comparable to the Rh supported on a CZ (Rh/CZ) catalyst with a Rh loading of 0.3 g/L, but after degradation treatment, emissions increased and were inferior to the Rh/CZ. X-ray diffraction and transmission electron microscopy of the catalyst powder showed that the alloy particles increased in size and underwent phase separation after degradation treatment. Furthermore, it was confirmed that iridium (Ir) was oxidized during the specimen preparation process. It is speculated that phase separation proceeds as iridium undergoes repeated oxidation and reduction during the catalyst production process and exposure to exhaust gases. We have clarified the degradation process of PdRuIr/CZ catalysts and concluded that iridium oxidation is one of the major factors causing phase separation of the alloy.
Motegi, Takuya, Tatara, Shunya, Takamoto, Shunpei, Doi, Kosuke
Coupled Analysis of First Principle Calculation and Chemical-Kinetics Simulation to Predict the Activity of Three Way Catalyst2024-32-00044/18/2025
This study proposes a technique to predict the catalytic activity of the CO-NO-O2 reaction using the first principle calculations without experiment. The proposed method consists of four steps. (1) Assuming the detailed chemical reactions based on the Langmuir-Hinshelwood mechanism. (2) Estimating the activation energy (Ea) for each detailed chemical reaction using first principle (e.g. Density Functional Theory: DFT) calculations. (3) Defining frequency factors (A) theoretically. (4) Inputting the estimated Ea and A values into simulation software for chemical-kinetics (e.g. exothermia suite) and running the simulation. The validity of the proposed method was evaluated by experiments. This study predicted the catalytic activities of Pt, Pd or Rh(111) surfaces. The predicted results qualitatively matched the experimental outcomes obtained from the Pt, Pd or Rh thin-film catalyst prepared by the “arc plasma method”.
Miura, Kazuya, Kusaba, Hiroki, Miyoshi, Tomoya, Yoshida, Hiroshi, Tsuchizaki, Hiroyuki, Machida, Masato
Effects of Post-Injection Strategy on the Performance of Diesel Catalyst-Heating Operation2025-01-84144/1/2025
Minimizing the time needed to achieve light-off temperatures in diesel engine aftertreatment devices is key to mitigate pollutant emissions during the first minutes of operation. Catalyst heating operation typically includes one or multiple post-injections late during the expansion stroke aimed to increase the enthalpy of the exhaust gases. However, post-injection retardability is constrained by low combustion efficiency and the formation of CO and unburned hydrocarbons that cannot be oxidized by a still-inactive oxidation catalyst. In this study, the effects of post-injection strategy on the performance and emissions of a medium duty diesel engine have been investigated experimentally, focusing on the impacts on post-injection retardability. A five injection strategy (two pilot, one main, two post) was implemented in the engine, and the injection duration ratio between the two post-injections has been varied systematically while performing post-injection timing sweeps to identify the trade-offs between exhaust enthalpy, emissions, fuel delivered by each post-injection, and post-injection timing. The exhaust enthalpy and the indicated specific CO and unburned hydrocarbon emissions increase as the post-injection retard for all the injection duration ratios. However, this effect is more dramatic for long first post injection durations and short second post injection durations (i.e., a high first-to-second post-injection duration ratio). For these cases, the fuel vaporization cooling effect of the first post-injection on the in-cylinder reactivity causes that both post injections burn together at lower in-cylinder temperatures than those of the other first-to-second injection duration ratios, leading to higher emissions with no significant advantages in exhaust enthalpy. In general, a fuel split ratio equal to 1 with half of the fuel injected in the second post-injection, which ignition is sustained by half of the fuel injected in the first post-injection provides better performance-emissions trade-off and higher post-injection retardability.
Lopez Pintor, Dario, Lee, Sanguk, Cho, Seokwon, Busch, Stephen, Wu, Angela, Narayanan, Abhinandhan, Abboud, Rami
Effect of Catalyst Coating Strategy on NOx Reduction and Passive Soot Oxidation for Selective Catalytic Oxidation-Selective Catalytic Reduction Catalyst on Diesel Particulate Filter2025-01-84904/1/2025
Selective catalytic oxidation/reduction catalysts coated on diesel particulate filters (SDPF) are an important technology route to meet next-stage emission regulations. The previous research of the research group showed that compared with SDPF coated with Cu-SSZ-13, the SDPF coated with novel selective catalytic oxidation-selective catalytic reduction (SCO-SCR) catalyst, which combined MnO2-CeO2/Al2O3 and Cu-SSZ-13, can simultaneously improve NOx reduction and soot oxidation performance. Catalyst coating strategy is an important parameter affecting the performance of SDPF. In this study, the effects of different coating strategies of SCO-SCR catalysts (C25, C50, C75, and C100) on the performance of NOx reduction and soot oxidation in SDPF were investigated. The results show that, as the inlet gas temperature increases, NO emissions first decrease and then increase, NOx conversion efficiency first increases and then decreases, and the rich-NO2 area, NH3 oxidation rate, N2O, CO, CO2 emissions, and pressure drop increase. By expanding the catalyst coating area, the NH3 oxidation rate, NOx conversion efficiency, NO2, N2O, CO, CO2 emission and pressure drop of filter wall all increased, the pressure drop of soot cake layer and NO emissions decreased. When the temperature is 450 °C, there are rich-NO2 areas at both the front end and rear end of C100. The 25% area at the rear end of the filter wall coated with SCO-SCR catalyst can increase NOx conversion efficiency and soot regeneration efficiency. While the impact on N2O generation is small. Still, it will lead to excessive NO2 emissions. The increased magnitude in NOx conversion efficiency and soot regeneration efficiency decease as the catalyst coating area expands.
Chen, Ying-jie, Tan, Piqiang, Yao, Chaojie, Lou, Diming, Hu, Zhiyuan, Yang, Wenming
Gasoline Particulate Filter Modeling with Catalytic Washcoat and Ash Accumulation and Transient Soot Distribution Prediction2025-01-84834/1/2025
The upcoming EURO 7 and EPA Tier 4 regulations and the possible China 7 are expected to tighten the tailpipe particulate emissions limits significantly. High performance Gasoline Particulate Filters (GPFs) with high filtration efficiency and low pressure drop would be mandated for gasoline engines to meet these stringent regulations. Due to packaging constraints, GPFs are often coated with three-way catalyst (TWC) materials to achieve four-way functionality. Ash accumulation in GPFs also has a significant impact on the performance of GPFs. This paper utilizes 3D CFD to predict the transient filtration efficiency and pressure drop of a washcoated GPF with ash accumulation during the soot loading process. Simulation results show a decent match with experimental data. The 3D CFD model also provides detailed information on soot penetration in the GPF wall substrate and soot cake characteristics on the wall. These information can be crucial for GPF wall substrate design and washcoating strategy design.
Yang, Pengze, Cheng, Zhen
A Study on Cetane on Demand Technology Part 1 - Development of Fuel Reformer to Improve Fuel Ignitability2025-01-84474/1/2025
The integration of low-octane gasoline with a compression ignition combustion system has been proposed as a strategy to reduce Well-to-Wheel CO2 emissions from automobiles using petroleum-based fuel. In the current situation where low-octane gasoline is not widely available in the market, onboard reforming of commercial gasoline to increase the cetane number (lower the octane number) allows for compression ignition combustion even with commercial gasoline. This requires “Cetane on Demand” technology, which enables compression ignition combustion with both commercial gasoline and low-octane gasoline. It is known that the ignition property of fuel is enhanced when the fuel is oxidized to generate hydroperoxides. Moreover, the use of N-hydroxyphthalimide (NHPI) as a catalyst promotes hydroperoxide generation at low temperatures. The objective of this study is to develop a device that enhances the ignition properties of gasoline through onboard fuel reforming. Initially, from the seven kinds of NHPI-supported solid catalysts, a catalyst appropriate for a flow reactor operating at ambient pressure was selected. The NHPI-supported ZSM-5 catalyst demonstrated the highest performance in hydroperoxide formation under flow reactor conditions. Subsequently, with a focus on onboard reforming, two types of reactors (spiral-type reactor and inner-circulation type reactor) and two methods of air introduction (metal mesh bubbler and mechanical stirring bubbler) to ensure adequate contact between the fuel, air, and solid catalyst were designed and prototyped. The combination of the spiral-type reactor and mechanical stirring air introduction exhibited the best performance in hydroperoxide formation.
Hashimoto, Kohtaro, Yamada, Yoshikazu, Matsuura, Katsuya, Kudo, Tomohide, Chishima, Hiroshi, Al-Taher, Maryam, Kalamaras, Christos, Albashrawi, Reem
Impact of Oxidation Catalyst Formulation and Space Velocity on Performance with Conventional and Renewable Fuels2025-01-84954/1/2025
Prior study with biodiesel and its blends with ultra-low sulfur diesel (ULSD) and renewable diesel (RD) showed that a commercial diesel oxidation catalyst (DOC) is unable to effectively oxidize neat biodiesel (B100) or high-level biodiesel blends injected into the exhaust of a diesel engine at challenging conditions of low temperature, high exhaust flow rate and high dosing rate. In steady-state performance tests, the performance of blends up to B50 in ULSD or RD was nearly equivalent to ULSD at the lowest exhaust flow rate or for exhaust temperature over 340°C for medium and high flows. ULSD blends above 50 vol% biodiesel exhibited reduced thermal efficiency and DOC outlet temperature with increasing dosing rate and required exhaust temperatures over 400°C to achieve similar performance as ULSD. For RD blends at higher flow rates and temperatures below 300°C even B10 blends showed some loss in performance at the highest dosing rates. Data showed an increase in lightoff temperature with an increase in biodiesel concentration in both the ULSD and RD blends. Here we conducted a limited study with higher catalyst volume and increased platinum group metal (PGM) loading to see if these factors would improve DOC performance with B100. ULSD, RD and B100 were run on steady-state performance test with the same DOC used previously. To assess the impact of PGM loading and catalyst volume we also used a three-way catalyst (TWC) for comparison to the DOC. The TWC consisted of two bricks and the test was run with one and both bricks to assess the impact of catalyst volume. The data showed that the single brick of TWC was marginally better than the DOC with better light off performance for B100 at low temperatures and exhaust flow rates. The entire TWC (two bricks) was significantly better than the DOC showing marginally better performance at low temperature and exhaust flow rate and significantly improved performance at low temperature and medium flow rate. The additional catalyst volume and higher overall catalyst loading produced better oxidation of B100 even at the most challenging conditions – with increased catalyst volume (increased residence time) have the largest effect.
Lakkireddy, Venkata, Weber, Phillip, McCormick, Robert, Howell, Steve
Fundamental Science on Oxygen Storage Capacity of Cerium Complex Oxides for Advanced On-Board Diagnostics (2) Quantitative Observation of Oxygen Released from Cerium Complex Oxides2025-01-84764/1/2025
In order to comply with the tightening of global regulations on automobile exhaust gas, further improvements to exhaust gas control catalysts and upgrades to on-board diagnostics (OBD) systems must be made. Currently, oxygen storage capacity (OSC) is monitored by front and rear sensors before and after the catalyst, and deterioration is judged by a decrease in OSC, but it is possible that catalyst deterioration may cause the rear sensor to detect gas that has not been sufficiently purified. It is important to observe the activity changes when the catalyst deteriorates in more detail and to gain a deeper understanding of the catalyst mechanism in order to create guidelines for future catalyst development. In this study, we used a μ-TG (micro thermogravimetric balance) to analyze in detail how differences in design parameters such as the type of precious metal, detection temperature, and mileage (degree of deterioration) affect the OSC rate in addition to the OSC of the ceria-based composite oxide of the entire catalyst. It was found that CZY has better durability in terms of both OSC rate and amount than CZ. Furthermore, by comparing the results of experiments using time-resolved dispersive X-ray absorption fine structure (DXAFS) using synchrotron radiation, the reduction behavior of ceria was analyzed in more detail.
Hamada, Shota, Uegaki, Shinya, Tanabe, Hidetaka, Nakayama, Tomohito, Jinjo, Itsuki, Kurono, Seita, Oishi, Shunsuke, Narita, Keiichi, Onishi, Tetsuro, Yasuda, Kazuya, Matsumura, Daiju, Tanaka, Hirohisa
High-Efficient and Cost-Effective Three-Way Catalyst Substrate Design for Plug-in Hybrid Electric Vehicle2025-01-85284/1/2025
China 6b regulation was fully implemented since July 2023 with very strict emission standards for HC, NMHC, NOx, and CO. The country is now also in the process of developing China 7 regulation, which will perhaps impose even stricter emission limits and extra criteria pollutants including NH3. Moreover, increasingly strict fuel consumption regulation has been implemented as well and it is highly possible that greenhouse gas emission limits will be included in the China 7 regulation. With the hybrid technology innovation, PHEVs are effective in fuel economy and emission reduction, which are favored by manufacturers and consumers, and leading to a rapid increase in market share. Through the optimization of hybrid architecture and the synergy of electric motors, the operating conditions of the hybrid engine have been optimized, making it more stable and avoiding extreme engine operating conditions compared to traditional ICE, which also provides possibilities for optimizing the after-treatment system design to achieve low cost and high efficiency at the same time. In this study, engine operating conditions and engine out emissions of a PHEV were analyzed through vehicle testing with WLTC cycle in lab. Emission tests were conducted using different catalyst systems to study the impact of different substrate design options including low mass Corning® FLORA® substrates with higher cell density on gaseous pollutant emissions. As a byproduct of secondary reactions on catalysts, the generation of NH3 is closely related to catalyst efficiency. This study also investigated the characteristics of NH3 emissions and proposed appropriate design to reduce NH3 emission. Additionally, the influence of thermal aging conditions on catalyst conversion efficiency was studied to explain the correlation between anti-ageing performance and the substrate design.
Wang, Jiming, Li, Chunbo, Feng, Xiangyu, Chen, Xiaolang, Boger, Thorsten, Tian, Lichen, Hu, Xianli, Zeng, Jun, Tian, Tian, Gao, Bojun, Li, Dacheng, Liu, Shicheng, Jiang, Fajun
Fundamental Science on Oxygen Storage Capacity of Cerium Complex Oxides for Advanced On-Board Diagnostics (1) Kinetic Observation of Cerium Valence Change Using Synchrotron Radiation2025-01-84744/1/2025
On-board diagnosis (OBD) of gasoline vehicle emissions is detected by measuring the fluctuations of the rear oxygen sensor due to the time-dependent deterioration of the oxygen storage capacity (OSC) contained in the automotive catalyst materials. To detect OBD in various driving modes of automobiles with an order of magnitude higher accuracy than before, it is essential to understand the OSC mechanism based on fundamental science. In this study, time-resolved dispersive X-ray absorption fine structure (DXAFS) using synchrotron radiation was used to carry out a detailed analysis not only of the OSC of ceria-based complex oxides, which had previously been roughly understood, but also of how differences in design parameters such as the type of precious metals, reducing gases (CO and H2), detection temperatures, and mileages (degree of deteriorations) affect the OSC rate in a fluctuating redox atmosphere. A fundamental characteristic was clearly demonstrated in ceria-based complex oxides: the oxygen release rate accompanying the generation of oxygen vacancies is overwhelmingly slower than the oxygen storage rate that restores the crystal structure. Another interesting result was revealed: when precious metals are supported, a competitive reaction occurs between the precious metal and the ceria-based complex oxide in the release/storage of oxygen, and the change in cerium valence from tetravalent to trivalent actually slows down. Furthermore, it was proven that CZY is more durable than CZ in terms of both OSC rate and amount. In this way, the basic scientific properties of ceria-based complex oxides, which are necessary for designing OBD logic, have been clarified.
Tanaka, Hirohisa, Matsumura, Daiju, Uegaki, Shinya, Hamada, Shota, Aotani, Takuro, Kamezawa, Saeka, Nakamoto, Masami, Asai, Shingo, Mizuno, Tomohisa, Takamura, Riku, Goto, Takashi
Degradation Analysis of Aged Fuel Cell Stack via Polarization Change Curve2025-01-70901/31/2025
A 20-cell self-humidifying fuel cell stack containing two types of MEAs was assembled and aged by a 1000-hour durability test. To rapidly and effectively analyze the primary degradation, the polarization change curve is introduced. As the different failure modes have a unique spectrum in the polarization change curve, it can be regarded as the fingerprint of a special degradation mode for repaid analysis. By means of this method, the main failure mode of two-type MEAs was clearly distinguished: one was attributed to the pinhole formation at the hydrogen outlet, and another was caused by catalyst degradation only, as verified by infrared imaging. The two distinct degradation phases were also classified: (i)conditioning phase, featuring with high decay rate, caused by repaid ECSA change from particle size growth of catalyst. (ii) performance phase with minor voltage loss at long test duration, but with RH cycling behind, as in MEA1. Then, an effective H2-pumping recovery is conducted, and MEA performance rejuvenated to the level of phase transition time (218h). It indicated the voltage loss at the performance phase is reversible, while the conditioning phase is not as expected. Therefore, there are few perquisites for the durability test, including proper selection of current density point as a baseline, test duration beyond the conditioning time, and effective recovery procedure; otherwise, the lifetime of the stack would be extremely underestimated. As massive voltage loss is from catalyst degradation in the conditioning phase for all MEAs and featuring irreversible, more understanding about catalyst degradation at the conditioning phase is suggested for further durability improvement.
Pan, Chenbing, Wu, Hailong, Ruyi, Wang
Enhanced High-Temperature Performance of NH 3 -SCR Catalysts for Lean-Burn Engines2025-01-70431/31/2025
NOx after-treatment has greatly limited the development of lean-burn technology for gasoline engines. NH3-Selective Catalytic Reduction (SCR) technology has been successfully applied to NOx conversion in diesel engines. For gasoline engines, SCR catalyst is required to maintain high activity over a higher temperature window. In this study, we utilized a turbocharged and intercooled 2.0 L petrol engine to investigate the NOx conversion of two zeolite-based SCR catalysts, Cu-SSZ-13 and Fe/Cu-SSZ-13, at exhaust flows ranging from 80 to 300 kg/h and exhaust temperatures between 550 to 600°C. The catalysts were characterized using SEM, ICP, XRD, H2-TPR, NH3-TPD, and other methods. The selected Fe/Cu-SSZ-13 catalyst showed higher NOx conversion (>80%) in the temperature range of 550~600oC and 80~300 kg/h exhaust gas flow. NOx output could be controlled below 10ppm. The characterization results showed that although the specific surface area and acidic sites decreased after the aging treatment for Fe/Cu-SSZ-13, they still retained active sites, showing higher activity and stability.
Pan, Shiyi, Wang, Ruwen, Zhang, Nan, Xu, Zhiqin, Hu, Jiangtao, Liao, Xiuke, Duan, Pingping, Chen, Ruilian
First Principle Study of Catalyst’s Influence on Self-Inhibition Effect and By-Products Formation of Lean NOx Trap2025-01-70421/31/2025
Lean NOx trap is a dedicated DeNOx catalyst for lean hybrid gasoline engines. Noble metals (usually platinum group metals) play the role of catalytic sites for NOx oxidation and reduction, which have significant impact of the performance of LNT. This work focuses on the influence of noble metal catalysts on self-inhibition effect from the view of competitive adsorption between NO and CO, and investigates the influence of CO self-inhibition effect on the main by-product of LNT: N2O formation. Adsorption configurations for NO, CO and N2O on noble metal clusters supported by γ-Al2O3(100) are confirmed. For detailed investigation, electron structures are analyzed by investigating Bader charge, DOS (density of state), charge density differences and COHP (crystal orbital Hamilton population) of selected configurations.The results show that CO self-inhibition effect is caused by competitive adsorption between CO and NO. The essence of competitive adsorption between CO and NO is that adsorption process of CO and NO on catalytic sites is similar. Excessive adsorption of CO on the catalytic site occupies the catalytic site and limits the NO adsorption and subsequent processes, making NO conversion efficiency decrease. Competitive adsorption between CO and NO will limit NO adsorption and dissociation, thus limiting N2O formation. Meanwhile, stronger adsorption of N2O on catalytic sites will make N2O desorption difficult.
Liu, Mingli, Liu, Yaodong, Qu, Hanshi, Duan, Jiaquan, Zhang, Qiqi, Qian, Dingchao, Wang, Zhenxi, He, Zhentao
Mesoscopic Heat and Mass Transfer Process in Catalyst Layer of Proton Exchange Membrane Fuel Cells under Cold Environment2025-01-70881/31/2025
To explore the heat and mass transfer processes within the low-temperature catalyst layer, a coupled heat and mass transfer lattice Boltzmann model and electrochemical model were established, creating a pore-scale model for heat and mass transfer in the catalyst layer. The influence of the catalyst layer parameters was investigated. The results indicate that as time progresses, heat gradually accumulates at the top of the catalyst layer (CL) and is transmitted towards the bottom. Once oxygen enters the CL, it quickly fills the pores within the CL, resulting in a rapid decrease in oxygen concentration within the ionomer. As the platinum volume fraction increases, there is a significant rise in temperature across the entire calculation domain. With the increasing platinum volume fraction, the current density also increases rapidly due to the larger reaction area. When the carbon volume fraction is 0.15, more oxygen enters the ionomer to participate in reactions, and the large porosity enhances thermal convection, leading to the highest temperature at this point. As the ionomer content increases, the area of the high-temperature red zone within the CL also expands. However, with a carbon volume fraction of 0.25, the diffusion of oxygen in the pores is reduced, leading to most of the oxygen entering the ionomer, resulting in the highest current density among the three cases. Nonetheless, since thermal convection is stronger when the I/C weight ratios is relatively small, the overall temperature remains high. As the I/C weight ratios increases, oxygen diffusion weakens, and the overall current density shows an upward trend.
Xu, Sheng, Chen, Xin, Sheng, Tao
Model Based Emissions and NVH Optimization2024-36-005912/20/2024
Throughout the years, the legislations which drive the vehicle development have experimented constant evolutions. Especially when it comes about pollutant emissions and NVH ( Noise, Vibration & Harshness). However, it is complex to understand which calibration strategy promotes the best balance about lowest levels of emissions, vibrations, and noise if considered the number of inputs to be explored, becoming the searching for the optimum calibration a huge challenge for the development engineering team. This work proposes a methodology development in which complex problems can be solved by model based solutions regarding the best balance finding of emissions reduction and noise attenuation. The methodology is based in machine learning approach which provides a virtual behavior of engine phenomena making possible a wider comprehension of the problem and hence the opportunity to explore enhanced solutions. The study case scenario used to apply the method was a 6.4 liters engine which presented a huge noise during the catalyst heating phase. The method allowed to find a calibration propose that could eliminate the noise without harming emissions levels. The methodology presented the capacity to solve the problem in a shorter time and higher quality than the conventional method. Based on its success, research is ongoing to refine the methodology to be applied in several other powertrain configuration.
Ruiz, Rodrigo Peralta Moraes, Santos, Lucas Resende, Nascif, Gabriel Nobre Alves, Oliveira Ribeiro, Douglas, Pereira, Willyan
Cracking Activity and Characterization of Magnesium Titanium Dioxide - Silicon Dioxide Catalysts2024-01-524112/10/2024
Purified nickel and a large number of MgTi2 / NiO2 catalysts with various MgTi2 loadings were produced using the traditional incipient wetness method. X-ray crystallography and Fourier-transform infrared spectroscopy were used to examine the catalysts. To understand the material's microstructure better, the researchers investigated oxygen adsorption at 90K. The amine titration method was used to investigate the acidic characteristics of these catalysts. In a study on cumene cracking, these catalysts were employed. The catalyst was found to be amorphous up to a loading of 12 weight percent MgTi2, but at higher loadings, crystalline MgTi2 phase formed on an amorphous silica substrate. When NiO2 is doped with more MgTi2, there are significant differences in the structure, surface acidity, and catalytic activity of the catalysts. Catalysts with a higher MgTi2 loading are noticeably more acidic than those with a lower MgTi2 loading. A correlation between the amount of cracking activity and the number of acid sites on the catalyst surface has been shown in numerous studies. Cumene cannot be cracked over the investigated catalysts unless the catalyst contains extremely acidic sites. Unmistakably Bronsted acid sites, with the breaking action attributed to a mechanism involving chromium ions. The results were validated by comparing them with relevant studies in the existing literature. These comparisons demonstrate consistency with similar research, confirming the effectiveness of the MgTi2/NiO2 catalysts.
Ashok Kumar, B., Dhiyaneswaran, J., Selvaraj, Malathi, Pradeepkumar, M., Shajeeth, S.
Effects of Fuel Distillation Characteristics on the Performance of Catalyst-Heating Operation in a Medium-Duty Off-Road Diesel Engine2024-01-427811/5/2024
Catalyst heating operation in compression-ignition engines is critical to ensure rapid light-off of exhaust catalysts during cold-start. This is typically achieved by using late post injections for increased exhaust enthalpy, which retardability is constrained by acceptable CO and unburned hydrocarbons emissions, since they are directly emitted through the tailpipe due to the inactivity of the oxidation catalyst at these conditions. Post-injection retardability has shown to be affected by the cetane number of the fuel, but it is unclear how other fuel properties affect the ability to retard the combustion. This study aims to understand the impact of the distillation characteristics of the fuel on the performance of catalyst heating operation and on post-injection retardability. In this study, experiments are performed in a single-cylinder medium-duty diesel engine fueled with three full boiling-range diesel fuels with different distillation curves using a five-injection strategy (two pilot, one main, two post) optimized for catalyst heating operation. The two post-injections are block-shifted to more retarded timings for three different first-post to second-post fuel split ratios and at a constant engine load. Decreasing the volatility of the fuel leads to higher exhaust enthalpy values and lower CO and unburned hydrocarbon emissions. The increase in exhaust enthalpy is caused by an additional fuel requirement to compensate for higher heat losses caused by higher flame-wall interactions with the less volatile fuels. The decrease in CO and unburned hydrocarbon emissions is caused by lower formation of overly-lean regions that do not burn properly using with the less volatile fuels. Thus, low volatility fuels improve the retardability of post injections. Chemical kinetic simulations are performed to better understand autoignition reactivity differences between fuels, concluding that fuel effects are more important for the pilot injections due to the low in-cylinder temperature and high in-cylinder pressure at the time of injection.
Lee, Sanguk, Lopez Pintor, Dario, Cho, Seokwon, Busch, Stephen
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