Iron-based composite nanostructure catalysts used to produce COx-free hydrogen from ammonia

Iron-based composite nanostructures with ceria or titania as shell coating on naked iron spheres were successfully synthesized and used to catalyze ammonia decomposition. The structure and texture of fresh and used catalysts were characterized by transmission electron microscopy, X-ray diffraction, in situ X-ray diffraction, temperature-programmed reduction by hydrogen, and N2 adsorption-desorption. For ammonia decomposition, the iron-based composite catalyst coated with cerium and titanium showed excellent catalytic activity compared with naked iron sphere catalyst, with the former yielding nearly 100% ammonia conversions at 650 °C and showing high stability in the catalysis test (for 60 h) at 600 °C with a space velocity of 24,000cm3gcat−1h−1. These results showed that adding cerium and titanium played a key role in improving catalytic activity for ammonia decomposition and enabling high thermal stability.