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Sulfur containing species as well as other polar molecules provide lubricity and thermal stability to diesel fuels. During the refining process to produce low and ultra-low sulfur diesel fuels, these components are removed. As a result, fuel additives such as lubricity agents and antioxidant may be added to protect fuel stability and prevent fuel pump wear. Some lubricity additives, such as dimer acids, resulted in fuel filter plugging. The plugging mechanism was related to the capability of aliphatic acids to form agglomeration by interactions with the overbased detergents, delivered into the fuel as oil contaminants. Other sources of acids, derived from thermal degradation, can lead to the same problem. In this study, individual lubricant additives were mixed in the fuel to form single- and dual-component systems. Levels of compatibility and amounts of interaction products were evaluated for individual solutions.

Sulfur poisoning from engine fuel and lube is one of the most recognizable degradation mechanisms of a NOx adsorber catalyst system for diesel emission reduction. Even with the availability of 15 ppm sulfur diesel fuel, NOx adsorber will be deactivated without an effective sulfur management. Two general pathways are currently being explored for sulfur management: (1) the use of a disposable SOx trap that can be replaced or rejuvenated offline periodically, and (2) the use of diesel fuel injection in the exhaust and high temperature de-sulfation approach to remove the sulfur poisons to recover the NOx trapping efficiency. The major concern of the de-sulfation process is the many prolonged high temperature rich cycles that catalyst will encounter during its useful life. It is shown that NOx adsorber catalyst suffers some loss of its trapping capacity upon high temperature lean-rich exposure.

Global emission legislations for diesel engines are becoming increasingly stringent. While the exhaust gas composition requirements for prior iterations of emission legislation could be met with improvements in the engine's combustion process, the next issue of European, North American and Japanese emission limits greater than 2005 will require more rigorous measures, mainly employment of exhaust gas aftertreatment systems. As a result, many American diesel OEMs are considering NOx adsorbers as a means to achieve 2007+ emission standards. Since the efficacy of a NOx adsorber over its lifetime is significantly affected by sulfur (“sulfur poisoning”), forthcoming reductions in diesel fuel sulfur (down to 15 ppm), have raised industry concerns regarding compatibility and possible poisoning effects of sulfur from the lubricant.