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Catalytic emission control systems are installed on nearly all automobiles and heavy-duty trucks produced today to reduce exhaust emissions for the vehicles to meet government regulations. Current systems can achieve very high efficiencies in reducing tailpipe emissions once the catalytic components reach their operating temperatures. They are, however, relatively ineffective at temperatures below their operating temperature windows, especially during the cold start period of the vehicles. With the increasingly stringent government regulations, reducing the emissions during the cold start period before the catalytic components reach their operating temperatures is becoming a major challenge. For cold start HC control, HC traps based on zeolites have been investigated and commercialized for certain applications. For cold start NOx control, especially in lean burn engine exhaust, NOx storage and release catalysts have been evaluated.

This paper describes the development and in-field application of a new type of metallic partial filter. The unique design of the filter is described. The performance of a complete system, consisting of an oxidation catalyst upstream of the new partial filter, is described, demonstrating the ability of the system to achieve over 70% particulate matter (PM) conversion. Finally, a field demonstration of the system retrofitted to different vehicles running in Seoul is described, demonstrating the performance and physical durability of the system is retained over 30,000 km of real-world operation.

This paper describes the development and characterization of a selective catalytic reduction (SCR) catalyst system for a typical EUIV heavy-duty diesel (HDD) engine. The performance of the SCR catalyst and the impact of catalyst volume are described. The effect of using an ammonia slip catalyst behind the SCR catalyst is investigated, before examples of the use of computer modelling to refine the optimum volume and urea injection strategy are given. Finally, the durability of the SCR catalyst is described. Taken as a whole, the results demonstrate how a combination of practical experiments and computer modelling can be used to refine the system and provide a cost-effective exhaust aftertreatment (EA) solution.

Particulate Matter (PM) emissions are of increasing importance, as diesel emissions legislation continues to tighten around the world. Diesel PM can be controlled using Diesel Particulate Filters (DPFs), which can effectively reduce the level of carbon (soot) emissions to ambient background levels. The Johnson Matthey Continuously Regenerating Trap (CRT®) [1], which will be referred to as the Continuously Regenerating DPF (CR-DPF) for the remainder of this paper, has been widely applied in Heavy Duty Diesel (HDD) applications, and has been proved to have outstanding field durability [2]. To widen the potential application of this system, addition of a platinum based catalyst to the DPF has been shown to lead to a higher PM removal rate under passive regeneration conditions, using the NOx contained in the exhaust gases.

Two campaigns measuring on-road emissions of 23 VN-trucks on a randomly chosen driving cycle, consisting of 10 miles two-lane and 8 miles four-lane road were performed. The first, during October 2004, showed tailpipe NOx emissions on fleet average of 1.06 g/bhp-hr including the time the exhaust gas temperature was below 200°C. The second, during June 2005, showed tailpipe NOx emissions on fleet average of 1.13 g/bhp-hr including the time the exhaust gas temperature was below 200°C. Complementary measurements in a SET-cycle (13 point OICA-cycle) on a chassis dynamometer showed a tailpipe emission of 0.008 g PM per bhp-hr. Moreover, cost analysis show that the diesel fuel consumption remains unchanged whether the truck running on ULSD is equipped with a Combined Exhaust gas AfterTreatment System (CEATS) installed or not.

On-road emission measurements of 23 VN-trucks on a randomly chosen driving cycle, consisting of 10 miles two-lane and 8 miles four-lane road, showed tailpipe NOx emissions on fleet average of 0.96 g/bhp-hr, or 1.06 g/bhp-hr when including the time the exhaust gas temperature was below 200°C. Complementary measurements in a SET-cycle (13 point OICA -cycle) on a chassis dynamometer showed a tailpipe emission of 0.008 g PM per bhp-hr. Moreover, cost analysis show that the diesel fuel consumption remains unchanged whether the truck running on ULSD is equipped with a Combined Exhaust gas AfterTreatment System (CEATS) installed or not.

This paper reviews field test results in 23 Volvo D12C non-Exhaust Gas Recirculation (EGR) diesel engines using continuously regenerating Diesel Particulate Filter (DPF) with Selective Catalytic Reduction (SCR) and ultra low sulfur diesel fuel at 4-10 ppm. This 2-year field test provided an opportunity to measure on-road nitrogen oxide (NOx) emissions, and to do in-depth analysis of the incombustible material remaining in the filters. In addition, two crankcase oils were used at 1.0% and 1.4% sulfated ash to provide enhanced information on the material collected in the filters, and on oil drain capability. The study demonstrates that the U.S. Environmental Pro-tection Agency (EPA) 2007 emissions can be met. After 2 years in the field the 23 trucks using the DPF-SCR system are still providing a very high NOx conversion of 75% on fleet average. The filter material contained only 2 wt-% carbon, which demonstrates the effectiveness of the DPF-SCR system in combusting soot.

The modern Diesel engine is one of the most versatile power sources available for mobile applications. The high fuel economy and power of the Diesel engine has long made it the choice for heavy-duty applications worldwide. Over the coming years, global emissions legislation applied to heavy-duty Diesel (HDD) engines will become more and more stringent, necessitating the use of advanced emissions control technologies. In particular, the coming exhaust gas emissions legislation focuses on particulate matter (PM) emissions and emissions of nitrogen oxides (NOx). A filtration device can control PM emissions, and a possible technology for the abatement of NOx emissions involves NOx absorber catalysts. This paper describes investigations into the activity and system behaviour of a prototype HDD exhaust system based on NOx absorber technology. The system consists of a “single leg” containing NOx absorber catalyst that is bypassed during rich regeneration of the NOx absorbers.

A 1-D numerical model describing the ammonia selective catalytic reduction (SCR) de-NOx process has been developed based on data measured on a laboratory microreactor for a vanadia-titania washcoated catalyst system. Kinetics for various NH3-NOx reactions were investigated, as well as those for ammonia, CO and hydrocarbon oxidation. The model has been successfully validated against engine bench measurements, over light-off and ESC tests, under a wide range of conditions, e.g. flow rate, temperature, NO2/NO ratio, and ammonia injection rate. A very good agreement between the experimental data and the model has been achieved. The model has now been used to predict the effect of NO2/NO ratio on NOx conversion, and the effect of different ammonia injection rates on the efficiency of the SCR process.

Selective Catalytic Reduction (SCR) systems will be widely used to meet the Heavy Duty Diesel (HDD) Euro IV emissions legislation. Reports on a number of demonstrations of such systems have already been published, but the long-term durability of such systems is still to be proven. The potential catalyst deactivation induced by oil-derived species and thermal processes have, up to now, received very little attention, despite the fact that these HDD emission control systems will need to be durable for distances of the order of 500,000 km or more. This paper describes the development and performance of a new family of SCR catalyst with very high thermal durability and poison resistance. The thermal durability of the catalyst was initially demonstrated within long-term, high temperature engine bench ageing studies.

The European research co-operation Lotus is presented. The main objectives of the project were i) to show the potential for a urea-based SCR system to comply with the EU standard of years 2005 and 2008 for heavy-duty Diesel engines for different driving conditions with optimal fuel consumption, ii) to reach 95 % conversion of NOx at steady state at full load on a Euro III engine, iii) to reach 75 % NOx reduction for exhaust temperatures between 200-300°C, and 85 % average NOx reduction between 200-500°C. The energy content of the consumed urea should not exceed 1.0 %, calculated as specific fuel consumption. These targets were met in May 2003 and the Lotus SCR system fulfilled the Euro V NOx legislative objectives for year 2008.

The tightening of Heavy Duty Diesel (HDD) emissions legislation throughout the world is leading to the development of emission control devices to enable HDD engines to meet the new standards. NOx and Particulate Matter (PM) are the key pollutants which these emission control systems need to address. Diesel Particulate Filters (DPFs) are already in use in significant numbers to control PM emissions from HDD vehicles, and Selective Catalytic Reduction (SCR) is a very promising technology to control NOx emissions. This paper describes the development and performance of the Compact SCR-Trap system - a pollution control device comprising a DPF-based system (the Continuously Regenerating Trap system) upstream of an SCR system. The system has been designed to be as easy to package as possible, by minimising the total volume of the system and by incorporating the SCR catalysts on annular substrates placed around the outside of the DPF-based system.

Increasingly stringent Diesel vehicle emissions legislation around the world means that advanced aftertreatment systems may be required to achieve the required nitrogen oxide (NOx) emissions rather than through engine control measures alone. As in lean-burn gasoline applications, NOx adsorber systems offer great potential for high level NOx conversion in Diesel exhaust, and their use on Diesel engines is an area of intense interest for possible use in light-duty and heavy-duty applications. This paper is concerned with the performance of advanced NOx adsorber catalysts developed specifically for the requirements of light-duty Diesel vehicles. Laboratory and engine bench data are discussed that demonstrate NOx conversions in excess of 90% over a wide temperature window can be achieved. The durability characteristics of these catalysts are also reported.

As legislation tightens in the Heavy Duty Diesel (HDD) area it is essential to develop systems with high activity and excellent durability for both Particulate Matter (PM) and NOx control. The Continuously Regenerating Trap (CRT™) system controls hydrocarbon (HC), CO and PM emissions from HDD vehicles with efficiencies of over 90%, and has demonstrated very good field durability over distances exceeding 700,000 km. The system is widely used in Europe, and is demonstrating the same high performance and excellent durability within field applications in North America. The Continuously Regenerating Trap (CRT™) system has been developed and patented by Johnson Matthey [1]. Throughout this paper this system will be referred to as the Continuously Regenerating Diesel Particulate Filter, CR-DPF. The CR-DPF comprises an oxidation catalyst, optimised for NO2 generation from the engine-out NOx, and a downstream DPF.

Future US emissions limits are likely to mean a sophisticated nitrogen oxide (NOx) reduction technique is required for all vehicles with a diesel engine, which is likely to be either NOx trap or selective catalytic reduction (SCR) technology. To investigate the potential of SCR for NOx reduction on a light duty vehicle, a current model vehicle (EUII M1 calibration), of inertia weight 1810 kg, was equipped with an urea-based SCR injection system and non-vanadium, non-zeolitic SCR catalysts. To deal with carbon monoxide (CO), hydrocarbon (HC) and volatile organic fraction (VOF), a diesel oxidation catalyst was also incorporated into the system for most tests. Investigations into the effect of placing the oxidation catalyst at different positions in the system, changing the volume of the SCR catalysts, increasing system temperature through road load changes, varying the SCR catalyst composition, and changing the urea injection calibration are discussed.