Deciphering the role of Pr on NH3 decomposition activity over Ni/Mg-Al mixed metal oxide catalyst

NH 3 is a promising hydrogen carrier and its decomposition commonly requires noble-metal catalysts i.e., Ru. Therefore, developing efficient Ni-based catalysts offers a cost-effective route for NH 3 cracking at low temperatures. The NH 3 cracking results revealed that an optimal loading of Pr modifier outperformed the conversion (95%) and H 2 formation rate of 21.3 mmol. g cat −1 . min at 600 °C (GHSV of 20 L. g cat −1 . h −1 ) and sustained performance over 100 h-on-stream on continuous operation without any noticeable deactivation compared to undoped 10% Ni/MgAl catalyst. Kinetic studies indicated that the inclusion of Pr drastically decreased the apparent activation energy (Ea) to 47.5 kJ/mol of the 10%Ni/Mg-Al catalyst. The promotional effect arises from Pr-induced oxygen vacancies that facilitate NH 3 activation and improved Ni dispersion that increases active site availability. This work clarifies the structure-activity relationship in rare-earth-promoted Ni catalysts and pave the way for designing efficient non-noble metal catalysts for sustainable hydrogen production.