Nitriding resistance of materials for enabling NH₃ cracking technologies above 550 °C (AmmoMat)

Due to the volatility of renewable energy sources the large-scale storage and distribution are becoming increasingly important. Hydrogen is a promising, carbon-emission-free, chemical storage medium, but its low volumetric energy density and difficulties with liquefaction limits its areas of application. NH₃ is emerging as a liquid organic hydrogen carrier, as it offers a high gravimetric hydrogen capacity (18 wt.%) and the possibility to utilize already existing infrastructure. However, high pressures and temperatures exceeding 750 °C are needed during subsequent NH₃ cracking to achieve a kinetically reasonably fast reaction and a sufficiently high conversion. These conditions lead to an enrichment of nitrogen in the material surface, which induces microstructural changes and thus material damage. This nitridation was extensively studied for the Haber-Bosch process at lower temperatures (up to 550°C), but not for ammonia cracking at higher temperatures. In order to advance cracker developments, there is an urgent need to identify or develop suitable materials with a sufficiently long service life and to ultimately achieve their certification. This project aims to create the basis for this and to identify the relationship between material damage and process parameters, and to develop a lifetime model.

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