Carbon monoxide detection and purification system for fuels cells

Abstract

The present invention provides an apparatus and method for determining the concentration of CO gas in a fuel reformate stream such as in a PEM fuel cell vehicle. This invention protects the fuel cell catalyst by controlling the reformate stream system to minimize the CO and reduce it by a novel catalyst system that selectively converts CO to methane but does not react with carbon dioxide and hydrogen. The catalyst may reduce the CO to methane by reaction with hydrogen. The preferred embodiment both monitors the CO by a thermal differential sensing means and an optical biomimetic sensor and or a conductivity sensor. These sensors respond to the CO gas and are monitored by one or more monitoring sensors such as the temperature and or conductivity difference between the control and the catalytic material such as nickel and in the biomimetic sensor an optical change is monitored. The optical sensing comprising a photon source optically coupled to the sensor and photodiode system, so that the photon flux is a function of at least one other sensor's response to the CO gas, e.g., transmits light through the sensor to the photodiode. The photocurrent from the photodiode is converted to a digital sensor reading value proportional to the optical characteristic(s) of the sensor(s) as a function of time and the data is loaded into a microprocessor or other logic circuit. In the microprocessor, the sensor readings are essentially used to calculate the CO concentration and control the process to maximize the fuel cell or to trigger a signal for service.