Reduction of Heavy-Duty Diesel Engine Emissions Using a High Molecular Weight Polymer Fuel Additive

Polyisobutylene (PIB), a high molecular weight polymer fuel additive, has been extensively tested in heavy-duty diesel engines to determine its effect on both controlled and presently un-controlled exhaust emissions. This work was performed at a TCEQ (Texas) and CARB (California) recognized laboratory using the official EPA transient cycle test protocol for on-road engine applications and the official ISO 8178 8-mode steady-state test protocol for off-road engine applications. Testing with California specified diesel fuels in several production diesel engine models resulted in exhaust particulate matter being reduced over both test protocols in all engines on the order of 20 to 50% while reducing NOx on the order of 5 to 25%. Idle particulate matter emissions were reduced on the order of 60%. Simultaneously, 1,3-butadiene, a high risk carcinogenic compound in diesel engine exhaust was essentially eliminated with the PIB additive treated fuel and all polycyclic aromatic hydrocarbons were reduced compared to the baseline exhaust emission data without PIB. These results and emission reductions were all obtained with a 5 ppm concentration of the PIB additive in CARB specification diesel and biodiesel fuels.