Promoted porous CO3O4-Al2O3 catalysts for ammonia decomposition
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摘要:
Transition metal catalysts have been considerably used for NH3 decomposition because of the potential application in COx-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 ℃ 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 diff raction (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.