Promoted porous Co3O4-Al2O3 catalysts for ammonia decomposition

Abstract

Transition metal catalysts have been considerably used for NH3 decomposition because of the potential application in CO x -free H2 generation for fuel cells. However, most transition metal catalysts prepared via traditional synthetic approaches performed the inferior stability due to the agglomeration of active components. Here, we adopted an efficient method, aerosol-assisted self-assembly approach (AASA), to prepare the optimized cobalt-alumina (Co3O4-Al2O3) catalysts. The Co3O4-Al2O3 catalysts exhibited excellent catalytic performance in the NH3 decomposition reaction, which can reach 100% conversion at 600 °C and maintain stable for 72 h at a gaseous hourly space velocity (GHSV) of 18000 cm3 gcat−1 h−1 . The catalysts were characterized by various techniques including transmission electron microscope (TEM), scanning electron microscope (SEM), nitrogen sorption, temperature-programmed reduction by hydrogen (H2-TPR), ex - situ / in - situ Raman and ex - situ / in - situ X-ray diffraction (XRD) to obtain the information about the structure and property of the catalysts. H2-TPR and in - situ XRD results show that there is strong interaction between the cobalt and alumina species, which influences the redox properties of the catalysts. It is found that even a low content of alumina (10 at%) is able to stabilize the catalysts due to the adequate dispersion and rational interaction between different components, which ensures the high activity and superior stability of the cobalt-alumina catalysts.