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The current European fleet of vehicles is ageing and lifetime mileages are rising proportionally. Consequently, a substantial fraction of the vehicle fleet is currently operating at mileages well beyond current durability legislation (≤ 160,000 km). Emissions inventories and models show substantial increases in emissions with increasing mileage, but knowledge of the effect of emissions control system deterioration at very high mileages is sparse. Emissions testing has been conducted on matched pairs (or more) of diesel and gasoline (and CNG) vehicles, of low and high mileage, supplementing the results with in-house data, in order to explore high mileage emission deterioration factors (DF). The study isolated, as far as possible, the effect of emissions deterioration with mileage, by using nominally identical vehicle models and controlling other variables.

Lean operating natural gas heavy duty applications have advantages in terms of lower CO2 and PM compared to Diesel applications. This makes operating heavy duty applications on natural gas attractive and currently, they do not have to implement an exhaust particulate filter. However, the challenge is controlling methane emissions over a range of vehicle operating conditions. Methane is extremely stable and light off occurs at temperatures above 400 °C, with high efficiency occurring >500 °C and requires high precious metal loaded catalysts in the range of 150 - 200 g/ft3. Under stoichiometric conditions, 500 °C can be met in many engine operating points however, for lean operating applications, the exhaust temperature can be significantly lower than 500 °C posing a significant challenge for exhaust catalytic CH4 control. This paper will discuss synthetic gas reactor study results using ozone in the feed gas to perform low temperature methane control.

The earliest public domain reference regarding full engine testing of an automotive catalyst was from January 1959, written by GM and presented at the annual SAE meeting in Detroit. This current publication will review the first public domain paper referencing different aftertreatment technologies (such as TWC, LNT, DPF and SCR, but not limited to these technologies) and compare the technologies to the current state of the art in aftertreatment technology. This historical review using a range of databases, will show how exhaust aftertreatment technologies have significantly enhanced emissions control over the last 60 years for both gasoline and diesel applications. A timeline will be given showing when various technologies were first presented into the public domain. This will indicate how long it has taken certain emissions control technologies to enter the market.

The exhaust emissions of two Euro 6 diesel cars with different emissions control systems have been evaluated both on the road and over various chassis dynamometer test cycles. European emissions limits are currently set using the New European Driving Cycle (NEDC), but the European Commission is preparing additional test procedures to ensure that emissions are well controlled both in real-world use and over the legislative test cycle. The main focus of this work on ‘Real Driving Emissions’ (RDE) is on measurements using Portable Emissions Measurement Systems (PEMS) in truly representative, on-road, driving. A key focus of the test programme, undertaken as a collaboration between AECC (the Association for Emissions Control by Catalyst) and Ricardo UK, was therefore the use of PEMS systems to measure on-road emissions of both gaseous pollutants and particulate matter. This included measurement of particle number emissions with a new candidate system for this type of measurement.

Understanding the behavior of automotive catalysts formulations under the wide range of conditions characteristic of automotive applications is key to the design of present and future emissions control systems. Platinum-based oxidation catalysts have been in use for some time to treat the exhaust of diesel-powered vehicles and have, as part of an emissions control package, successfully enabled compliance with emissions legislation. However, progressively stringent legislated limits, coupled with the need to reduce vehicle manufacturing costs, is incessantly demanding the development of new and improved catalyst formulations for the removal of pollutants in the diesel exhaust. With the introduction of low sulfur diesel fuel, and the advantageous decline in Palladium prices with respect to Platinum, bimetallic Pt:Pd-based catalysts have found an application in diesel after treatment.

This paper describes the development of a novel low precious metal nano-technology catalyst (Nanocat) and its application in a modern European gasoline vehicle. Three iterations of low precious metal nano-technology catalysts were tested on a Euro 3 certified gasoline vehicle over the European drive cycle (EDC). Engine dynamometer lean spike ageing was used to simulate aged catalysts representing approximately 100 000 km on-road ageing. The fresh and aged nano-technology catalysts were tested and compared to the vehicle production catalyst. The third iteration of fresh nano-technology catalyst met Euro 3 emissions legislation and also met Euro 4 limits for HC and NOx. However, after lean spike ageing the NOx levels exceeded Euro 3 limits but the HC tailpipe remained within Euro 4 limits. The ageing process caused an 18% reduction in the NOx conversion but the HC conversion was maintained.