Activated Carbon Coated Polymeric Foam for Hydrocarbon Vapor Adsorption 2005-01-1103
The Environmental Protection Agency (EPA) has enacted increasingly stringent limits on hydrocarbon emissions for vehicles used in the United States. The Partial Zero Emissions Vehicle (PZEV) requires a lower level of emissions than previously accepted. OEMs, Tier 1, and various suppliers have been working to cost effectively meet this challenge.
Activated Carbon (AC) in the form of pellets, granules, or as part of an extruded ceramic has been used in emission control systems. Wood based activated carbon, treated with phosphoric acid, seems to offer the optimal pore structure, adsorption, and desorption characteristics required.
This paper discusses materials used to meet the challenges of the PZEV requirement, highlights the differences between two types of hydrocarbon adsorbing materials, and offers a modified test method useful for evaluating filter medium performance at the lower hydrocarbon concentrations associated with PZEV emission levels.