Catalytic Ammonia Decomposition for COx-Free Hydrogen Production over Fumed SiO2-Supported Co-Ni Bimetallic Catalysts

Hydrogen production from ammonia decomposition using cheap metal catalysts at moderate temperatures is facing challenges. In this study, a fumed SiO2-supported Co-Ni bimetallic catalyst (Co9Ni1/SiO2) was prepared by coimpregnation. The catalyst achieved a 99.55% NH3 conversion and a 55.99 mmol g(cat)(-1) h(-1) H-2 yield at 550 degrees C with a w8 hly space velocity (WHSV) of 30,000 mL g(cat)(-1) h(-1). Besides, the catalyst exhibited good stability and reproducibility during a 60 h continuous test at 500-550 degrees C. XRD and TEM results confirmed that Co and Ni were well dispersed on the catalyst surface and exhibited a strong synergistic effect. Kinetic tests showed that the bimetallic Co-Ni catalyst effectively reduced the apparent activation energy of the ammonia decomposition reaction compared to monometallic Co or Ni catalysts. This study provides a new case for designing and developing efficient and cheap catalysts for ammonia decomposition.