Ru-Based Catalysts for Ammonia Decomposition: A Mini-Review

Ammonia with a hydrogen content of 17.6 wt % is viewed as a promising hydrogen carrier because the infrastructures for its production, storage, and transportation have been well established. The challenge is that currently the straight production of H2 from NH3 only works at high temperatures. To date, various metal-based catalysts have been developed for NH3 decomposition, among which the Ru-based ones are the most superior due to the suitable Ru–N binding energy. In the past decade, efforts have been put in to improve the performance of Ru-based catalysts, and the target is to lower Ru loading and reaction temperature. A large variety of support and promoter materials were studied, and advanced techniques were employed to disclose the relationship between catalytic performance and catalyst structure. In this paper, we conduct a review on the materials that are used as supports and/or promoters, focusing specifically on the carbon (CNTs, CNFs, and graphene) and metal oxide (Al2O3, MgO, SiO2, and others) materials. Moreover, the reaction mechanism for ammonia decomposition over Ru-based catalysts is described, and future works on designing novel catalysts and unravelling the catalyst structure–activity relationship are proposed.