Machine Design

Fuel cells may say goodbye to platinum catalysts

A nickel-tin catalyst may replace platinum in a low-temperature process for making hydrogen fuel from plants.

According to engineers at the University of Wisconsin-Madison, the new catalyst, together with a second innovation that purifies hydrogen for use in fuel cells, offers a new method for making the transition from fossil fuels to renewable hydrogen-based power.

"Platinum is very effective but it's also very expensive," says James Dumesic, a professor of chemical and biological engineering. "It's also problematic for large-scale power production because platinum is already in demand for fuel-cell anode and cathode materials," he adds.

The single-step process uses temperature, pressure, and a catalyst to convert hydrocarbons such as glucose. Resulting products consist of 50% hydrogen with the rest being carbon dioxide and gaseous alkanes. More refined molecules, such as ethylene glycol and methanol, almost completely convert to hydrogen and carbon dioxide. Because plants grown as fuel crops absorb the carbon dioxide released by the system, the process is greenhouse-gas neutral. The process takes place in a liquid phase at 440°F without vaporizing water. This is said to represent a major energy savings compared to ethanol production or conventional fossil-fuel-based hydrogen-generation methods that boil away water.

Researchers are trying to create a combined process where the nickel-tin catalyst reforms oxygenated hydrocarbons to produce relatively clean hydrogen. The hydrogen then passes to a second-stage ultrashift catalyst that further purifies it and removes carbon monoxide.

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