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 NH3. 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/MgAl2O4-LDH shows high NH3 conversion (-88.7%) and H2 production rate (-1782.6 mmol g-(1) h-(1)) at 30,000 L. kg-(1) h-(1) and 600 degrees C, which is 1.68 times as large as that of Ni/MgAl2O4-MM. The performance remains stable over 30 h. The characterizations manifest that the high specific surface area of Ni/MgAl2O4-LDH can introduce highly dispersed Ni on the surface. Kinetics analysis implies promoted NH3 decomposition reaction and alleviated H-2 poisoning for Ni/MgAl2O4-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 NH3. This indicates that enhanced NH3 decomposition performance can be ascribed to the strengthened NH3 decomposition reaction and weakened H-2 poisoning by the highly dispersed Ni on the MgAl2O4-LDH surface. This work provides an opportunity to develop highly active and cost-effective catalysts to produce hydrogen via NH3 decomposition. (c) 2021 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.

Automated summary

This study develops an efficient and cost-effective catalyst for hydrogen production via ammonia decomposition by using non-precious nickel as the catalyst. The Ni/MgAl2O4-LDH catalyst exhibits high ammonia conversion and hydrogen production rates, with stable performance over time. The highly dispersed nickel on the MgAl2O4-LDH surface plays a crucial role in enhancing the catalytic performance.