Hydrogen combustion engines (HICE) offer many advantages: converting a diesel version to hydrogen is significantly less expensive than replacing the powertrain with one powered by a fuel cell and their pollutant emissions are much lower than those from fossil fuel engines.
However, while they do not emit carbon, they produce nitrogen oxides (Nox) which react with other compounds present in the atmosphere to form ozone and harmful fine particles. The role of the catalytic exhaust is to limit these emissions.
The team of Professor Fudong Liu, from UCR, has just demonstrated that the addition of Y zeolites to platinum (already contained in catalytic filters) considerably improved the degradation of Nox. By modifying the reaction between hydrogen and Nox, zeolites convert them into harmless nitrogen gas and water vapor.
Nitrogen oxide emissions divided by five
The study showed that, compared to a conventional catalytic exhaust, the amount of nitrogen oxides converted to harmless substances increased four to five times (at an engine temperature of 250 degrees Celsius), for a model that incorporates zeolites.
A big advantage is that zeolites are inexpensive materials with a well-defined crystal structure; composed mainly of silicon, aluminum and oxygen atoms. By physically mixing them with platinum, the researchers created a system that effectively captures water generated during the hydrogen combustion process and promotes nitrogen reduction.
The laboratory study, which is the subject of a patent application, could very quickly find commercial outlets. In particular through BASF, financier of the research project.
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