Hydrogen Production from Ammonia Decomposition: A Mini-Review of Metal Oxide-Based Catalysts

Efficient hydrogen storage and transportation are crucial for the sustainable development of human society. Ammonia, with a hydrogen storage density of up to 17.6 wt%, is considered an ideal energy carrier for large-scale hydrogen storage and has great potential for development and application in the "hydrogen economy". However, achieving ammonia decomposition to hydrogen under mild conditions is challenging, and therefore, the development of suitable catalysts is essential. Metal oxide-based catalysts are commonly used in the industry. This paper presents a comprehensive review of single and composite metal oxide catalysts for ammonia decomposition catalysis. The focus is on analyzing the conformational relationships and interactions between metal oxide carriers and active metal sites. The aim is to develop new and efficient metal oxide-based catalysts for large-scale green ammonia decomposition.

Emerging trends in research and development on earth abundant materials for ammonia degradation coupled with H2 generation

Ammonia, as an essential and economical fuel, is a key intermediate for the production of innumerable nitrogen-based compounds. Such compounds have found vast applications in the agricultural world, biological world (amino acids, proteins, and DNA), and various other chemical transformations. However, unlike other compounds, the decomposition of ammonia is widely recognized as an important step towards a safe and sustainable environment. Ammonia has been popularly recommended as a viable candidate for chemical storage because of its high hydrogen content. Although ruthenium (Ru) is considered an excellent catalyst for ammonia oxidation; however, its high cost and low abundance demand the utilization of cheaper, robust, and earth abundant catalyst. The present review article underlines the various ammonia decomposition methods with emphasis on the use of non-noble metals, such as iron, nickel, cobalt, molybdenum, and several other carbides as well as nitride species. In this review, we have highlighted various advances in ammonia decomposition catalysts. The major challenges that persist in designing such catalysts and the future developments in the production of efficient materials for ammonia decomposition are also discussed.

Catalytic ammonia reforming: alternative routes to net-zero-carbon hydrogen and fuel

Ammonia is an energy-dense liquid hydrogen carrier and fuel whose accessible dissociation chemistries offer promising alternatives to hydrogen electrolysis, compression and dispensing at scale. Catalytic ammonia reforming has thus emerged as an area of renewed focus within the ammonia and hydrogen energy research & development communities. However, a majority of studies emphasize the discovery of new catalytic materials and their evaluation under idealized laboratory conditions. This Perspective highlights recent advances in ammonia reforming catalysts and their demonstrations in realistic application scenarios. Key knowledge gaps and technical needs for real reformer devices are emphasized and presented alongside enabling catalyst and reaction engineering fundamentals to spur future investigations into catalytic ammonia reforming.

Applications of rare earth oxides in catalytic ammonia synthesis and decomposition

Due to their unique structural and electronic properties, rare earth oxides have been widely applied as supports and promoters in catalytic ammonia synthesis and decomposition.