Experimental Study of Influence of Gasoline Fuel with MMT on Aging Performance of Three-Way Catalyst

Abstract

The octane enhancing fuel additive Methylcyclopentadienyl Manganese Tricarbonyl (MMT) is widely used in China to meet market demand for octane in the unleaded gasoline pool, as the use of gasoline of the appropriate octane level is critical to obtaining optimal vehicle fuel economy. The impact of combustion products resulting from the use of MMT-containing gasoline on vehicle emissions control components has long been debated. In order to better understand this issue, a fundamental research program was undertaken to investigate the interactions of combustion products from MMT-containing gasoline with high cell density (600 cpsi) catalysts during severe catalyst operating conditions typical of those used to accelerate catalyst aging for the vehicle durability demonstration process. The paper reports on tests conducted to evaluate the influence of engine running condition, the absence or presence of MMT (at 18 mg Mn/l), and the impact of catalyst inlet temperatures on deposition phenomena occurring at the catalyst face that can lead to plugging. Additionally, a 1000 h test based upon the Type V durability procedure was conducted using MMT-containing gasoline (also at 18 mg Mn/l) to evaluate the impact of the additive under longer term exposure conditions more representative of those dynamic mode operation encountered during typical real-world vehicle operation. Results were consistent with the conclusion that catalyst backpressure was influenced primarily by the test cycle condition, as backpressure increase was only observed during continuous long term exposure of catalysts to MMT-containing fuel at the most severe catalyst inlet temperatures (820 °C) under steady-state operating conditions. Backpressure increase was not obviously observed under dynamic operating conditions regardless of the MMT concentration or temperature.

F2012-A03-024