Christopher T. Holt

Fuel processing catalysts based on nanoscale ceria

Abstract The water-gas shift (WGS) reactor is a key component in fuel processors, but existing WGS catalysts are unsuitable for transportation applications, since the iron-chrome catalysts used at high temperatures are relatively inactive, and the copper-based catalysts used at low temperature tend to degrade under the severe conditions encountered in an automotive system. NexTech Materials has developed hydrothermal synthesis methods for dispersed suspensions of nanoscale ceria and ceria-zirconia, to give more active WGS catalyst, as well as more efficient and rugged catalyst packaging. The resulting WGS reactors based on ceramic monoliths loaded with Pt/ceria catalysts provide a technically viable and cost-effective option for automotive fuel processors.

Carbon monoxide sensor for PEM fuel cell systems

Power generation systems based on Proton-exchange membrane (PEM) fuel cells require sensors to detect carbon monoxide to extremely low levels (� 1 ppm) in the presence of hydrogen and other gaseous components (nitrogen, carbon dioxide, methane and steam). The CO sensors capable of working in reducing environments are almost non-existent. Development of a new CO sensor stable in H2-rich environment is described. The novel sensing approach is based on the adsorption of CO onto a film of an inorganic material that allows CO detection by monitoring resistance changes of the film in a simulated reformed gas, rich in H2. When suitable materials were used for the thick film approach, the resistance of the device exhibited a rapid and reversible sensitivity to carbon monoxide in the range 0‐5000 ppm over a period of several days, in the presence of hydrogen and nitrogen. # 2002 Elsevier Science B.V. All rights reserved.

Sensing of carbon monoxide gas in reducing environments

The change in resistance of thin-films of CuCl upon exposure to carbon monoxide is developed as the basis for sensing CO gas in reducing environments. Several methods of preparation of thin films of CuCl films were examined. Films prepared by solvent evaporation under ambient conditions showed good sensitivity for CO in the presence of hydrogen gas. The optimum sensing temperature was found to be 50 8C. We propose a hole conduction mechanism for CO sensing by CuCl films. # 2002 Elsevier Science B.V. All rights reserved.

HYDROCARBON AND SULFUR SENSORS FOR SOFC SYSTEMS

The following report summarizes work conducted during the Phase I program Hydrocarbon and Sulfur Sensors for SOFC Systems under contract No. DE-FC26-02NT41576. For the SOFC application, sensors are required to monitor hydrocarbons and sulfur in order to increase the operation life of SOFC components. This report discusses the development of two such sensors, one based on thick film approach for sulfur monitoring and the second galvanic based for hydrocarbon monitoring.