Process Purifies Hydrogen Fuel Over a Broad Temperature Range

University of Science and Technology of China, Hefei

The catalyst shows great potential to thoroughly guard the fuel cell during not only continuous operation but also during frequent cold start periods even in extremely cold conditions. (Image: LU Junling research group)

Hydrogen is considered one of the most promising clean energy sources. Hydrogen fuel cells offer high energy conversion efficiency and zero emissions. But the development of hydrogen fuel cells faces many challenges, including the issue of carbon-monoxide (CO) poisoning of the fuel cell electrodes.

Currently, hydrogen is mainly derived from processes such as steam reforming of hydrocarbons like methanol and natural gas, and water gas shift reaction. The resulting hydrogen usually contains 0.5 to 2 percent of trace CO. As the heart of hydrogen fuel cell vehicles, fuel cell electrodes are easily “poisoned” by CO impurity gas, resulting in reduced battery performance and shortened life, which severely hampers the application fuel cells in vehicles.

Earlier research identified a method called preferential oxidation in CO in hydrogen (PROX) as a promising way to remove trace amounts of CO from hydrogen using catalysts. But existing PROX catalysts can only work in high temperatures (above room temperature) and within a narrow temperature range, making it impractical for applications such as fuel cell vehicles that must be reliable even in winter months.

A new structure of atomically dispersed iron hydroxide on platinum nanoparticles was designed to efficiently purify hydrogen fuel over a broad temperature range of 198–380 Kelvin, which is approximately -103 °F to 224 °F or -75 °F to 107 °C. The material provides a thorough protection of fuel cells against CO poisoning during both frequent cold starts and continuous operation in extremely cold temperatures.

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