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 N 2 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 , 000 cm 3 g cat − 1 h − 1 $24,000{\mathrm{cm}}^3{\mathrm{g}}_{\mathrm{cat}}^{-1}{\mathrm{h}}^{-1}$ . These results showed that adding cerium and titanium played a key role in improving catalytic activity for ammonia decomposition and enabling high thermal stability .