Although in the European Union in general no metal containing additives are used, in 2009 a limitation of manganese in gasoline fuel up to 6 mg manganese per liter was introduced in the revised Fuels Quality Directive.
In this paper the influences and risks of metal-based additives on the aging of exhaust system components were detected, using the example of the currently allowed manganese content of 6 mg per liter. The legislative endurance test, the Standard Road Cycle (SRC) over the useful life period of 160,000 km conforming to EC Regulation 692/2008 was used.
Investigations were carried out with two endurance tests with metal-free-fueled and metal-containing-fueled (reference fuel plus metallic additive) vehicles on a certified chassis dynamometer. The two identical vehicles were both equipped with a typical state of the art downsized DISI engine with Euro 5 application. Euro 5 reference fuel was used as base gasoline. Exhaust emissions were analyzed in fixed intervals over run time in the form of NEDC tests. For better understanding of the NEDC emission results, the analysis was supported by measurements of oxygen storage capacity (OSC), endoscopy and computer tomography of the catalyst. The results are presented and discussed.
It is shown that long term compliance to Euro 5 emission limits with state of the art exhaust gas after treatment systems (like the chosen Euro 5 concept) cannot be ensured if the fuel includes metal-based additives (like 6 mg manganese per liter in this investigation). Increasingly stringent emission limit values require improvements in fuel quality. The use of manganese containing additive in fuel provokes risks for modern engines and the necessary highly efficient exhaust gas aftertreatment systems and thus for the environment.