H2 Production via Ammonia Decomposition Using Non-Noble Metal Catalysts: A Review

Abstract

The wide-spread implementation of the so-called hydrogen economy is currently partially limited by an economically feasible way of storing hydrogen. In this context, ammonia has been commonly presented as a viable option for chemical storage due its high hydrogen content (17.6 wt%). However, its use as an energy carrier requires the development of catalytic systems capable of releasing hydrogen at adequate rates and conditions. At the moment, the most active catalytic systems for the decomposition of ammonia are based on ruthenium, however its cost and scarcity inhibit the wide scale use of these catalysts. This issue has triggered research on the development of alternative catalysts based on more sustainable systems using more readily available, non-noble metals mainly iron, cobalt and nickel as well as a series of transition metal carbides and nitrides and bimetallic systems, which are reviewed herein. There have been some promising cobaltand nickel-based catalysts reported for the decomposition of ammonia but metal dispersion needs to be increased in order to become more attractive candidates. Conversely, there seems to be less scope for improvement of iron-based catalysts and metal carbides and nitrides. The area with the most potential for improvement is with bimetallic catalysts, particularly those consisting of cobalt and molybdenum.

Effect of Magnetic Inducement in Preparation of Ni/Ce‐doped Al2O3 for Ammonia Decomposition

“…CO causes deactivation of the H 2 fuel cell electrodes and CO 2 has many environmental impacts . Ammonia decomposition was reported as a potential clean H 2 production process since the reaction produces H 2 without CO and CO 2 emissions as shown in equation …”

“…Ammonia (NH 3 ) is considered as an excellent hydrogen carrier for on‐site H 2 generation. One mole of ammonia contains 17.8 wt% hydrogen and can be easily transported in the liquid phase at 298 K and a pressure of 8 atm . Unfortunately, Ruthenium (Ru), which is an active catalyst for this reaction, is expensive.…”

Ammonia decomposition over cobalt/carbon catalysts—Effect of carbon support and electron donating promoter on activity

“…the cobalt-support interaction [17]. However, a recent review of the decomposition of ammonia decomposition using non-noble metals [23] reveals the lack of systematic investigation on the development of these catalysts and the need of fundamental understanding of the effects of catalyst parameters on the resulting activity. By using a range of carbon supports with different physical and chemical properties, this paper reveals the effect of metal dispersion, metal particle size, support porosity and the electronic modification of the active sites of cobalt/carbon catalysts on the decomposition of ammonia catalytic activity, providing guidelines for future catalyst development in the field.…”

Fast Development of Self‐Assembled, Highly Oriented Polymer Thin Film and Observation of Dual Sensing Behavior of Thin Film Transistor for Ammonia Vapor

“…We observed the almost similar results for before exposure and after exposure, that is, Au electrode is almost unaffected in presence of NH 3 . It is important to mention here that the interaction of ammonia molecules with Pd‐electrode results in the formation of hydrogen molecules due to catalytic activity as :The presence of H 2 molecules in Pd‐metal resulted increase in contact resistances due to spill over mechanism as reported by other researchers . Therefore, AFM examination using phase image before and after exposure endows slight change in phase having Pd electrode, whereas in SPC it is almost the same for both the electrodes (i.e., Au & Pd).…”