Reduction of Nano-Particle Emissions from Gasoline 2-stroke Engines Using CLM™ Ceramic Exhaust Filters

GEO2 Technologies has developed an extruded fiber-based cross linked microstructure (CLM™) for use as a nano-particulate filter in gasoline 2-stroke exhaust emission control. CLM™ materials exhibit high porosity, narrow pore-size distribution, robust thermo-mechanical properties, and are extruded into high cell density honeycomb structures for wall-flow filter applications. GEO2 has demonstrated basic emission performance and durability of the CLM™ filter on a Piaggio 50cc scooter as well as on a 29cc Homelite leaf blower. The results show significant reduction in particulate emissions of greater than 97% while maintaining gas phase emissions (leaf blower) and without significant impact on engine performance or power output. In addition, a 16,000 km dynamometer durability test was conducted on the Piaggio scooter. During testing, ash loading in the CLM™ filter exceeded 10 grams/liter. Compared to the original muffler, this high ash load produced only a modest increase in exhaust system restriction (4.2% from 7.2kPa to 7.5kPa) and a small decrease in peak power (3.7% from 2.7KW to 2.6KW). These results were achieved by optimization of the test system for filtration versus flow through catalysis. The test system was developed with low initial backpressure (5kPa) since it was known that restriction would increase over the course of testing due to a build-up of inorganic particulates in the filter.