Catalyst support effect on ammonia decomposition over Ni/MgAl2O4 towards hydrogen production

Ammonia is a prospective fuel for hydrogen storage and production, but its application is limited by the high cost of the catalysts (Ru, etc. ) to decompose NH 3 . Decomposing ammonia using non-precious Ni as catalysts can therefore improve its prospects to produce hydrogen. This work proposes several Ni/MgAl 2 O 4 with the support properties tuned and investigates the support effect on the catalytic performance. Ni/MgAl 2 O 4 -LDH shows high NH 3 conversion (∼88.7%) and H 2 production rate (∼1782.6 mmol g −1  h −1 ) at 30,000 L. kg −1  h −1 and 600 °C, which is 1.68 times as large as that of Ni/MgAl 2 O 4 -MM. The performance remains stable over 30 h. The characterizations manifest that the high specific surface area of Ni/MgAl 2 O 4 -LDH can introduce highly dispersed Ni on the surface. Kinetics analysis implies promoted NH 3 decomposition reaction and alleviated H 2 poisoning for Ni/MgAl 2 O 4 -LDH. A roughly linear relationship is obtained by fitting the curves of dispersed Ni on the surface vs the reaction orders regarding H 2 and NH 3 . This indicates that enhanced NH 3 decomposition performance can be ascribed to the strengthened NH 3 decomposition reaction and weakened H 2 poisoning by the highly dispersed Ni on the MgAl 2 O 4 -LDH surface. This work provides an opportunity to develop highly active and cost-effective catalysts to produce hydrogen via NH 3 decomposition.