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Fleet average SULEV30 emissions over FTP-75 must be met under full implementation of US Tier 3/LEV III emission regulation in 2025. The majority of SULEV30 certified 2021 model year vehicles are equipped with ≤ 2L displacement engines and some models adopt hybrid powertrain systems. Pickup trucks account for > 20% of passenger vehicles in the US. They could represent a quick route to meet fleet average SULEV30 targets. The newest pickup truck models are typically ULEV50 or ULEV70 certified. To reach SULEV30 or lower emission category, total tailpipe emissions must be reduced by more than 40%. Improvement of cold start emission is essential because over 70% of regulated emission is emitted during the first 60 seconds of a drive cycle with current engine and aftertreatment technology. High porosity (HP) ceramic substrate is designed to reduce thermal mass and time required to reach three-way catalyst (TWC) active temperature compared to conventional ceramic substrates.

Today the Ammonia Selective Catalytic Reduction (SCR) system with good NOx conversion is the emission technology of choice for diesel engines globally. High NOx conversion SCR systems combined with optimized engine calibration not only address the stringent NOx emission limits which have been introduced or are being considered for later this decade, but also reduce CO2 emissions required by government regulations and the increase in fuel economy required by end-users. Reducing the packaging envelope of today's SCR systems, while retaining or improving NOx conversion and pressure drop, is a key customer demand. High SCR loadings ensure high NOx conversion at very low temperatures. To meet this performance requirement, a High Porosity Substrate which minimizes the pressure drop impact, was introduced in SAE Paper 2012-01-1079 [1], [2], [3].

Ammonia Selective Catalytic Reduction (SCR) is adapted for a variety of applications to control nitrogen oxides (NOx) in diesel engine exhaust. The most commonly used catalyst for SCR in established markets is Cu-Zeolite (CuZ) due to excellent NOx conversion and thermal durability. However, most applications in emerging markets and certain applications in established markets utilize vanadia SCR. The operating temperature is typically maintained below 550°C to avoid vanadium sublimation due to active regeneration of the diesel particulate filter (DPF), or some OEMs may eliminate the DPF because they can achieve particulate matter (PM) standard with engine tuning. Further improvement of vanadia SCR durability and NOx conversion at low exhaust gas temperatures will be required in consideration of future emission standards.

Ammonia Selective Catalytic Reduction (SCR) is a key emission control component utilized in diesel engine applications for NOx reduction. There are several types of SCR catalyst currently in the market: Cu-Zeolite, Fe-Zeolite and Vanadia. Diesel vehicle and engine manufacturers down select their production SCR catalyst primarily based on vehicle exhaust gas temperature operation, ammonia dosing strategy, fuel quality, packaging envelope and cost. For Vanadia SCR, the operating temperature is normally controlled below 550oC to avoid vanadium sublimation. In emerging markets, the Vanadia SCR is typically installed alone or downstream of the DOC with low exhaust gas temperature exposure. Vanadia SCR is also utilized in some European applications with passive DPF soot regeneration. However, further improvement of Vanadia SCR NOx conversion at low exhaust gas temperatures will be required to meet future emission regulations (i.e.: HDD Phase 2 GHG).

Selective catalyst reduction (SCR) using cordierite honeycomb substrate is generally used as a DeNOx catalyst for diesel engines exhaust in both on-road and commercial off-highway vehicles to meet today’s worldwide emission regulations. Worldwide NOx emission regulations will become stricter, as represented by CARB2027 and EuroVII. Technologies which can achieve further lower NOx emissions are required. Recently, several technologies, like increased SCR catalyst loading amount on honeycomb substrates, and additional SCR catalyst volume in positions closer to the engine are being considered to achieve ultra-low NOx emissions. However, undesirable pressure drop increase and enlarging after treatment systems will be caused by adopting these technologies. Therefore, optimization of the material and honeycomb cell structure for SCR is inevitable to achieve ultra-low NOx emissions, while minimizing any system drawbacks.

Honeycomb substrates are widely used to reduce harmful emissions from gasoline engines and are exposed to numerous thermal shocks during their lifetime making thermal shock resistance one of the key factors in designing honeycomb substrates. More stringent emission regulations will require the honeycomb substrates to be lighter in weight to improve light-off performance and to have better thermal shock resistance than conventional honeycomb substrates to handle higher expected temperature gradients. Thermal shock resistance is generally evaluated on a substrate by evaluating the thermal strain caused by temperature gradients inside the substrate during durability testing [1,2]. During the test, a heated substrate is cooled at a surface face to generate temperature gradients while the temperature inside the honeycomb substrate is monitored by multiple thermocouples.

Development of the ultra thin wall ceramic catalytic substrate is necessary to meet increasingly strict emissions regulations. The cell walls need to be thinner in order to improve the warm-up characteristics related to the reduction of emissions and to lower the back pressure. However, the thinner the wall thickness, the smaller the mechanical strength of the substrate becomes. For substrates with 2.5mil wall thickness, we densified a conventional material with 35% porosity to less than 30%[1] to improve erosion resistance. Furthermore, for substrates less than 2.5mil wall thickness, a denser material and strengthened end surface is necessary to protect against erosion. In addition to that, we think that a reinforced periphery is necessary for isostatic strength. In this paper, we evaluated the effect of a densified material, strengthened end surface, and a reinforced periphery.

The present paper describes the results of a joint development program focussing on a system approach to meet the EURO IV emission standards for an upper class passenger car equipped with a newly developed high displacement gasoline engine. Based on the well known catalyst systems of recent V6- and V8-engines for the EURO III emission standards with a combination of close coupled catalysts and underfloor catalysts, the specific boundary conditions of an engine with an even larger engine displacement had to be considered. These boundary conditions consist of the space requirements in the engine compartment, the power/torque requirements and the cost requirements for the complete aftertreatment system. Theoretical studies and computer modeling showed essential improvements in catalyst performance by introducing thin wall substrates with low thermal inertia as well as high cell densities with increased geometric surface area.

The LEV II and SULEV/PZEV emission standards legislated by the US EPA and the Californian ARB will require continuous reduction in the vehicles' emission over the next several years. Similar requirements are under discussion in the European Union (EU) in the EU Stage V program. These future emission standards will require a more efficient after treatment device that exhibits high activity and excellent durabilty over an extended lifetime. The present study summarizes the findings of a joint development program targeting such demanding future emission challenges, which can only be met by a close and intensive co-operation of the individual expert teams. The use of active systems, e.g. HC-adsorber or electrically heated light-off catalysts, was not considered in this study. The following parameters were investigated in detail: The development of a high-tech three-way catalyst technology is described being tailored for applications on ultra thin wall ceramic substrates (UTWS).