Reformulating Gasoline for Lower Emissions Using the Fuel Additive MMT® 2002-01-2893
Throughout the world, governments are promulgating regulations that are intended to improve air quality. Some of these regulations affect the physical and chemical properties of gasoline. Consequently, refiners are under increasing pressure to reformulate their gasoline to be lower emitting when handled and combusted. These regulatory actions have also greatly reduced flexibility in the fuel formulation process. In many cases, refiners are attempting to reduce gasoline vapor pressure, sulfur, aromatic, and olefin content while simultaneously tightening distillation characteristics by removing butane and reducing the use of heavy reformate and FCC fractions. Because butane, aromatics and olefins can contribute substantially to pool octane levels, blending clean-burning gasoline with the required octane rating for acceptable vehicle performance can be difficult. Use of the “fuel additive methylcyclopentadienyl manganese tricarbonyl” (MMT®) not only helps maintain vehicle emission system activity, but effectively increases gasoline octane rating, thus enabling refiners to increase the volume of clean-burning low octane streams blended directly into the gasoline pool.
Several different aspects of the impact of fuel reformulation on emission system durability will be discussed in this paper. First, the long-term impact of fuel formulation on vehicle emission system performance is studied. The effect of blending fuels with and without the additive MMT® to meet various fuel standards is then explored and the effect of this formulation strategy on vehicle emissions is evaluated. In particular, the emissions benefit conveyed by specifically obtaining the last increment of octane with MMT® instead of other conventional measures is examined. Using MMT® in this manner allows heavy aromatic blend streams to be replaced with lighter, more paraffinic components, which lowers aromatic levels and distillation temperatures. Therefore, gasoline blended with MMT® via this approach is inherently cleaner-burning than gasoline blended without the additive.