Title : Enhancing hydrogen production: Acidic-basic structural modification of nickel-based catalysts for ammonia decomposition
Abstract:
The increase in global sustainable green energy and hydrogen fuel trend towards net zero emission for the transport sector expected to surge hydrogen production. The decarbonization of energy processes will boost the use of hydrogen carriers like ammonia, methanol and methyl-cyclo-hexane. Ammonia seems to be an excellent choice, due to its high hydrogen content compared to other hydrocarbon streams. However, the catalytic decomposition of ammonia is still challenging in term of sustainable catalyst development. Ammonia decomposition requires several steps comprising adsorption over active catalyst/support, enough binding energy for nitrogen-hydrogen (N-H) bond activation for hydrogen abstraction via dehydrogenation followed by desorption of N2 and H2. Several catalysts were explored for ammonia cracking showed the most active catalysts. However, these catalysts required selected supports and promoters to upsurge the catalytic activity for greater ammonia conversion and lowering the cracking temperature. The objective of the study was to modify the acid-base surface of catalyst structure, by impregnating metal promotors of Na, K and Ba to Ni oxide and using moderate acidic surface support of gamma alumina for ammonia conversion [1]. Metallic oxides of Co and La were also used to enhance surface basicity by introducing transition and rare earth metals to incorporate with Ni oxide for better dehydrogenation of ammonia at lower temperature. The modification of Ni oxide structure with promoter is expected to enhance bifunctionality of the catalyst by expanding promotor-metal-support interaction. The catalytic reactivity over trimetallic catalysts was systematically influenced by their basic-acidic property that promoted ammonia dehydrogenation and catalyst activity.
