A Novel Solid Oxide Fuel Cell Based Catalytic Converter Replacement for Enhanced Emission Control and Power Generation in Automotive Exhaust

Increased concerns over climate change, limited fossil fuel resources, emissions, and poor air quality has created a greater need for sustainable energy systems. The need for increased sustainable energy systems has created largely two cooperative movements: 1) technologies that are considered renewable or more environmentally friendly and 2) higher efficiency. The automotive industry has long been a target for increasing efficiency and decreasing emissions. Current emission control systems rely heavily on the usage of precious metal based catalytic converters. Traditional catalytic converters convert incomplete combustion products into carbon dioxide and water vapor. During this conversion, any remaining chemical energy within the exhaust is lost to waste heat production. In order to achieve increased efficiency and reduced pollutant emission, the remaining chemical energy in the exhaust must be transformed into usable energy. A Solid Oxide Fuel Cell (SOFC) stack is therefore integrated into the exhaust system of a traditional internal combustion engine in place of the current upstream catalytic converter. A SOFC stack would eliminate the need to maintain stoichiometric exhaust conditions, and would allow the recovery of any remaining chemical energy in the exhaust stream. The SOFC stack creates the potential for electrical power generation from the exhaust, while significantly improving emission reduction in a lean environment when compared to the traditional catalytic converter. Initial testing indicates that a typical internal combustion engine operating at stoichiometric conditions results in an exhaust composition of ~2-3% H₂ and CO and ~1% mixed hydrocarbons. These exhaust constituents may be used by the SOFC for electrical power generation. Simultaneously, the SOFC stack has demonstrated an ability to decrease hydrocarbon, carbon monoxide, and nitrogen oxide emission by up to 50% when compared to a traditional platinum foil based catalytic converter.