Thermocatalytic Ammonia Decomposition – Status and Current Research Demands for a Carbon‐Free Hydrogen Fuel Technology

Abstract

Hydrogen storage materials and technologies are deemed as the cornerstone towards a world economy less reliant on, and ultimately independent of fossil resources. Ammonia is considered among the most efficient carbon‐free hydrogen carriers because of its relatively high gravimetric and volumetric hydrogen storage capacities and, equally important, ease of transport and storage. In addition, the well‐established chemical production of ammonia (preferably a green Haber‐Bosch process) would accelerate the immediate introduction of hydrogen into energy infrastructure. Thermocatalytic decomposition of ammonia yields clean, COx‐free hydrogen, but is energy intensive and currently performed with expensive Ru‐based catalysts. The development of more efficient catalysts based on more abundant and cheaper elements is indispensable for future wide‐scale industrial application. Therefore, the conceptualization of strategies and challenges for material developments, study and optimization of ammonia decomposition catalysts as well as their in situ/operando characterizations are pivotal aspects to be considered.

Challenges and advancement in direct ammonia solid oxide fuel cells: a review

“…In the scope of thermocatalytic ammonia cracking, the most precious metals used as catalysts include chromium (Cr), cobalt (Co), copper (Cu), iron (Fe), iridium (Ir), nickel (Ni), palladium (Pd), platinum (Pt), rhodium (Rh) and ruthenium (Ru) on metal oxides. 89–92 The catalytic activity and performance of different metal catalysts follow the order of Ru > Ni > Rh > Co > Ir > Pt ≅ Fe > Cr > Pd > Se ≅ Cu > Te > Pb, respectively. 92 By far, Ru-based catalysts have shown the highest ammonia conversion, but the high cost associated with Ru calls for finding other alternative materials or implementing advanced techniques like 3D printing to achieve higher performance with metals like Fe or Ni.…”

Recent Progress on Hydrogen Production from Ammonia Decomposition: Technical Roadmap and Catalytic Mechanism

“…This is due to the strong hydrogen bonds present within ammonia molecules, which demand a high level of energy to break apart. As a result, ammonia molecules break down into hydrogen and nitrogen [10,13,26,27]. Therefore, ammonia decomposition without a catalyst is not practical, as it necessitates high temperature ammonia molecules, which demand a high level of energy to break apart.…”

“…Therefore, ammonia decomposition without a catalyst is not practical, as it necessitates high temperature ammonia molecules, which demand a high level of energy to break apart. As a result, ammonia molecules break down into hydrogen and nitrogen [10,13,26,27]. Therefore, ammonia decomposition without a catalyst is not practical, as it necessitates high temperature and energy consumption as well as having a low reaction rate.…”

“…To produce clean H 2 , various technologies have been developed, such as thermocatalytic NH 3 decomposition, photocatalytic NH 3 decomposition, plasma-catalytic NH 3 decomposition, and electrocatalytic NH 3 decomposition. Figure 2 shows the advantages and disadvantages of each method [ 10 , 11 , 13 , 14 , 15 , 16 , 17 , 18 ]. Understanding these methods is key to determining the current capabilities of the NH 3 -to-H 2 conversion technologies.…”

Unveiling the mechanism of thermal catalytic oxidation of HCHO from the kiln exhaust gas using Sc-decorated Cr2CO2-MXenes

“…4,5 Thermal catalytic oxidation relies on catalysts to oxidatively decompose HCHO by heating and supplying energy. 6 The reported thermal catalysts include noble metals (Pt, Ru 7,8 ) and non-noble metal oxides (TiO 2 , MnO 2 , and Fe 2 O 3 (refs. 4, 9 and 10)).…”