The effect of fuel additive catalyzed regeneration of diesel particulate filters was studied for manganese and manganese plus copper additives. The primary objectives of the study were to define any reaction between cordierite cellular substrate filter and the additive ash, to evaluate any changes in filtration characteristics of the filter within a 10,000 mile test, and to investigate the effects of fuel additive upon the regeneration characteristics.
There was no evidence of chemical reaction between ash and the ceramic filter, nor were there any changes observed in the filtration pressure drop and efficiency. Use of manganese and manganese plus copper additives produced a dramatic reduction in particulate ignition temperature, to as low as 400°C at 16.75% oxygen. The magnitude of reduction, and the increase in regeneration frequency were found to be proportional to the additive concentration. Maximum filter temperature during regeneration was found to be proportional to the average particulate loading at regeneration, and was not related to the oxygen concentration. An oxygen concentration-ignition temperature relationship was found for each additive concentration. The metal additive ash appeared to be totally collected within the filter.
The fuel additive combinations used in this study appear to offer a viable approach to controlling diesel particulate regeneration, and to allow regeneration within the conditions achieved within the normal driving cycle for light duty diesel vehicles. Regeneration characteristics of these additives at higher concentrations should be defined to find the optimum tradeoff between ease and control of regeneration, and filter pressure drop resulting from additive ash accumulation. Other additive candidates should also be evaluated to define the best system.