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Gasoline particulate filters (GPF) have become a standard aftertreatment component in Europe, China, and since recently, India, where particulate emissions are based on a particle number (PN) standard. The anticipated evolution of regulations in these regions towards future EU7, CN7, and BS7 standards further enhances the needs with respect to the filtration capabilities of the GPFs used. Emission performance has to be met over a broader range in particle size, counting particles down to 10nm, and over a broader range of boundary conditions. The requirements with respect to pressure drop, aiming for as low as possible, and durability remain similar or are also enhanced further. To address these future needs new filter technologies have been developed. New technologies for uncatalyzed GPF applications have been introduced in our previous publications.

The gasoline particulate filter (GPF) represents a practical solution for particulate emissions control in light-duty gasoline-fueled vehicles. It is also seen as an essential technology in North America to meet the upcoming US EPA tailpipe emission regulation, as proposed in the “Multi-pollutant Rule for Model Year 2027”. The goal of this study was to introduce advanced, uncoated GPF products and measure their particulate mass (PM) reduction performance within the existing US EPA FTP vehicle testing procedures, as detailed in Code of Federal Regulations (CFR) part 1066. Various state-of-the-art GPF products were characterized for their microstructure properties with lab-bench checks for pressure drop and filtration efficiency, then pre-conditioned with an EPA-recommended 1500 mile on-road break-in, and finally were tested on an AWD vehicle chassis-dyno emissions test cell at both 25°C and -7°C ambient conditions.

India BS6 Stage2 (2023) regulations demand all gasoline direct injection (GDI) vehicles to meet particulate number emissions (PN) below 6x10+11# per km. Gasoline particulate filters (GPF) are a proven technology and enable high PN filtration efficiencies throughout the entire vehicle lifetime. One challenge for GPF applications could be the changing emission performance characteristics as a function of mileage due to collected ash and/or soot deposits with implications on back pressure losses. The main objective of this technical contribution is to study the above-mentioned challenges while applying Indian driving conditions and typical Indian climate and other ambient conditions. The substrate technology selected for this study is a high porosity GPF designed to enable the integration of a three-way functionality into the GPF, commonly described as catalyzed GPF (cGPF).

With the introduction of EU6d and CN6 all vehicles with gasoline direct injection and many with port fuel injection engine will be equipped with a gasoline particulate filter (GPF). A range of first generation filter technologies has been introduced successfully, helping to significantly reduce the tailpipe particulate number emissions. The continued focus on particulate emissions and the increasing understanding of their impact on human health, combined with the advanced emission regulations under RDE conditions results in the desire for filters with even higher filtration efficiency, especially in the totally fresh state. At the same time, to balance with the requirements on power and CO2, limitations exist with respect to the tolerable pressure drop of filters. In this paper we will report on a new generation of gasoline particulate filters for uncatalyzed applications.

Diesel particle filters (DPF) have become a standard aftertreatment component for all current and future on-road diesel engines used in the US. In Europe the introduction of EUVI is expected to also result in the broad implementation of DPF's. The anticipated general trend in engine technology towards higher engine-out NOx/PM ratios results in a somewhat changing set of boundary conditions for the DPF predominantly enabling passive regeneration of the DPF. This enables the design of a novel filter concept optimized for low pressure drop, low thermal mass for optimized regeneration and fast heat-up of a downstream SCR system, therefore reducing CO₂ implications for the DPF operation. In this paper we will discuss results from a next-generation cordierite DPF designed to address these future needs.

With the introduction of the current EU5 standards the diesel particulate filter has become a key element in the aftertreatment of diesel passenger cars. The upcoming future emission standards target primarily a further reduction in NOx emission as well as reduced fleet average CO₂ emissions. Although the particulate filter has no direct influence on the reduction of these species, the needs of future aftertreatment systems impose additional requirements on advanced filter technologies. In this paper we are introducing two new filter products based on a new low porosity aluminum titanate family that complement the current DuraTrap® AT filter products. The new products offer the potential for an increased soot mass limit or a significant reduction in pressure drop. The enhanced performance of the new filter products is discussed and demonstrated in a large number of experimental data obtained in engine bench tests.

To meet the future emission targets for Diesel engines, one trend is the use of Catalyzed Diesel Particulate Filters (CDPF). Catalyzing the filter, however, alters filter behavior. In particular, alteration in filter permeability imparts a significant change in the filter's performance. To understand the impact of the catalyst coating on a DPF, engine tests have been conducted to measure the pressure drop across DPFs with different catalyst coatings, cell densities, and soot loadings. The tests were performed over a range of engine speeds and loads, with a corresponding range in exhaust flow rates and temperatures. A pressure drop model based on previous work for uncatalyzed filters has been modified and validated for CDPFs. To achieve optimum design for DPF's, a parametric study comparing the influence of catalyst, cell density, wall thickness, filter length and diameter was done.

Quantitative in-use pressure measurements were taken from packaging ceramic substrates with the SoftMountSM technology and two more traditional technologies, stuffing and tourniquet. Each technology was assessed using four separate mat materials. Mat selection enhanced the application of the SoftMountSM technology through the reduced pressures applied to the substrate during packaging. High temperature and low temperature thermal cycling studies were performed on the canned converters for the three packaging technologies so that an evaluation could be made of converter durability. The SoftMountSM packaging technology yielded the lowest pressures of all the processes studied, regardless of mat type. The laminar hybrid mat evaluated yielded the best combination of pressure and durability performance. Low temperature residual shear strengths following thermal cycling of the converters showed good correlation between the SoftMountSM technology and the stuffing method.

An analytical model for estimating shear and bending stresses during canning of cordierite ceramic catalyst supports is presented. These stresses arise when the radial pressure distribution is nonuniform due, primarily, to variations in gap bulk density (GBD ) of intumescent mat around the perimeter of the substrate. Variations in GBD can occur during canning, regardless of the canning technique, due to anisotropic can stiffness or component tolerances or mat overlap. The model helps relate shear and bending stresses to substrate size and orientation, elastic modulii, cell size and wall porosity. If these stresses approach the corresponding strength of substrate, a shear crack may develop during or after the canning process depending on the magnitude of stress. A special test fixture was developed to measure the shear strength of ceramic catalyst supports, with different cell sizes, before and after the application of washcoat.

As demand for wall-flow Diesel Particulate Filters (DPF) increases, accurate predictions of DPF behavior, and in particular their pressure drop, under a wide range of operating conditions bears significant engineering applications. In this work, validation of a model and development of a simulator for predicting the pressure drop of clean and particulate-loaded DPFs are presented. The model, based on a previously developed theory, has been validated extensively in this work. The validation range includes utilizing a large matrix of wall-flow filters varying in their size, cell density and wall thickness, each positioned downstream of light or heavy duty Diesel engines; it also covers a wide range of engine operating conditions such as engine load, flow rate, flow temperature and filter soot loading conditions. The validated model was then incorporated into a DPF pressure drop simulator.

With stricter emissions standards, low back pressure requirements, and 100,000 mile durability specifications, ceramic catalysts have undergone significant developments over the past few years. The thrust in the ceramics area has centered on thin-wall structures to minimize back pressure and on high cell density for rapid light-off in close-coupled applications. The thin-wall structures are extruded from low expansion cordierite ceramic with adequate strength and thermal shock resistance equivalent to those of standard cordierite substrate. Examples of thin-wall substrate include 350XT which is extruded from a very low expansion dense cordierite ceramic, and 400/4 and 600/4 cell structures extruded from a low expansion modified cordierite ceramic. This paper will focus on the high fatigue resistance, excellent conversion efficiency, and low back pressure of 350 XT substrates with advanced washcoat system.

Preliminary back pressure and adsorption performance results are reported for two activated carbon honeycomb materials. The carbon impregnated honeycomb (CIH) material is porous ceramic honeycomb with a complete impregnation and coating of activated carbon on all ceramic surfaces. It offers the potential to be a permanent odor filter in that it can be in situ electrically regenerated. It has adsorption performance similar to commercially available layered filters, but has much lower back pressure. The second material is an activated carbon honeycomb (ACH) and is not ceramic-based as is CIH. As such, it has much more activated carbon and superior adsorption performance. The back pressure is low, as with CIH. It has significant potential as a high-performing disposable odor filter.

The monolithic, large frontal area (LFA), extruded ceramic substrates for diesel flow-through catalysts offer unique advantages of design versatility, longterm durability, ease of packaging and low Cost [1, 2]*. This paper examines the effect of cell density and cell size on catalyst light-off performance, back pressure, mechanical and thermal durability, and the steady-state catalytic activity. The factors which affect these performance characteristics are discussed. Certain trade-offs in performance parameters, which are necessary for optimum systems design, are also discussed. Following a brief discussion of design methodology, substrate selection, substrate/washcoat interaction and packaging specifications, the durability data for ceramic flow-through catalysts are summarized. A total of over 18 million vehicle miles have been successfully demonstrated by ceramic LFA catalysts using the systems design approach.

High temperature modulus of rupture (MOR) data, published previously, show that the ceramic catalyst supports get stronger with temperature due to the absence of water vapor and closure of microcracks which would otherwise act as stress concentrators [1, 2 and 3]*. The increased MOR value is partially responsible for the excellent durability of ceramic catalyst supports at high temperature. In this paper, we will present the compressive strength data of ceramic substrates at high temperature, namely the crush strength along B-axis and biaxial compressive strength of the whole substrate. Since the honeycomb strength is directly related to that of the individual cell wall, the compressive strength should also increase with temperature similar to the modulus of rupture. Accordingly, the ceramic substrates are capable of supporting higher mounting pressures exerted by the intumescent mat at high temperature [4].

The preconverter is an essential element of exhaust gas treatment to help meet the tighter emission standards of TLEV and LEV levels. Its design must be chosen so as to meet the simultaneous requirements of compactness, faster light-off, low back pressure, high temperature durability and low cost. This paper presents design options for a ceramic substrate and durable package which lead to an optimum and cost-effective preconverter system. Preliminary data for high temperature physical durability of selected converter systems are presented. Performance parameters for light-off activity and back pressure are also computed and compared with those of standard substrates used in underbody application. Laboratory tests comprising of axial push-out test, high temperature vibration test, exhaust gas simulation test and the engine dynamometer test demonstrate the viability of ceramic preconverters for automotive application.

This paper details the development of the EX-80 composition, a new cordierite material for use as a diesel particulate filter (DPF), that was developed based on the following objectives; (1) improved thermal durability, (2) high filtration efficiency and (3) low pressure drop. The achievement of these goals was demonstrated through engine testing, stress modeling, and other evaluations. EX-80 has a low coefficient of thermal expansion (CTE) averaging less than 4x10-7°C-1 (25°C-800°C), the Modulus of Rupture (MOR) averages greater than 350 psi and the Modulus of Elasticity (MOE) averages less than 0.8 x 106 psi. The improvement of these three properties has resulted in improved thermal durability for EX-80 as compared to the current Corning DPF compositions (EX-47, EX-54 and EX-66). The new cordierite composition has been designed to achieve a low pressure drop as a function of soot loading (0.30 inHg/gm of soot collected), coupled with high efficiency, averaging greater than 90%.

The motorcycle emissions regulations for both two-stroke and four-stroke engines, which are receiving worldwide attention, will go into effect in the very near future. To meet these regulations, the motorcycles will require a catalyst in conjunction with the muffler due to space limitations. The combination of high engine speeds, high vibrational acceleration, high HC and CO emissions, high oxidation exotherms, and stringent durability requirements, points to cordierite ceramic substrate as an ideal catalyst support. However, as an integral unit within the muffler, its packaging design must be capable of withstanding isothermal operating conditions which may exceed the upper intumescent temperature limit of the ceramic mat. This paper describes a durable packaging design for the ceramic catalyst which employs a hybrid ceramic mat, special end rings and gaskets, and high strength stainless steel can.

The stringent durability requirements approaching 100,000 vehicle miles for automotive substrates and 290,000 vehicle miles for large frontal area diesel substrates for 1994+ model year vehicles call for advanced packaging designs with thick ceramic mats and high mount densities. The latter result in high mounting pressure on the substrate and enhance its mechanical integrity against engine vibrations, road shocks and back pressure forces. A novel measurement technique which applies a uniform biaxial compressive load on the lateral surface of ceramic substrates, thereby simulating canning loads, is described. The biaxial compressive strength data obtained in this manner help determine the maximum mounting pressure and mat density for a durable packaging design. The biaxial compressive strength data for both round and non round substrates with small and large frontal area are presented.

The current automotive catalytic converter is highly dependable and provides excellent emissions reduction while at the same time it offers little resistance to the flow of gasses through the exhaust system. As automobile performance requirements increase, and as the allowable tailpipe emissions are tightened, there is a need on the one hand to reduce the back pressure even further, and on the other, to increase the already excellent catalytic performance. This paper will analyze the substrate factors which influence the pressure drop and conversion efficiency of the catalyst system. The converter frontal area has the most significant influence on both pressure drop and conversion efficiency, followed in order by part length, cell density, and wall thickness.