Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
7718057 | International Journal of Hydrogen Energy | 2014 | 8 Pages |
Abstract
Ammonia decomposition over Ni-loaded SiO2 catalysts (Ni/SiO2) was observed in a fixed-bed reactor at different temperatures (ranging from 773 to 973 K) and ammonia feeding rates (ranging from 1200 to 18,000 hâ1). As support materials, several porous and inert SiO2 particles with different mean pore diameters (d¯) ranging from 7.7 to 34.8 nm were used to clarify the effect of pore diameter on the kinetic parameters for catalytic ammonia decomposition. The Ni/SiO2 catalyst with the smallest pores, d¯ = 7.7 nm, showed the highest activity at temperatures below 923 K, while the activity of this catalyst at 973 K was lower than that of catalysts with larger pores. Kinetic analysis indicated that the activation energy for d¯ = 7.7 nm was significantly decreased at higher temperatures, suggesting the occurrence of strong diffusion resistance of ammonia molecules in the pores. Our experiments also confirmed that almost complete decomposition of ammonia could be achieved over Ni/SiO2 with d¯ = 26.7 nm at 973 K and a gas hourly space velocity as high as 42,000 hâ1.
Related Topics
Physical Sciences and Engineering
Chemistry
Electrochemistry
Authors
Ryosuke Atsumi, Reiji Noda, Hideyuki Takagi, Luigi Vecchione, Andrea Di Carlo, Zaccaria Del Prete, Koji Kuramoto,