Low-Cost Hydrogenation Catalyst

An inexpensive aluminum-iron alloy may give precious-metal catalysts a run for their money when it comes to mediating selective hydrogenations, a multinational research team reports in Nature Materials (DOI: 10.1038/nmat3347). Platinum-group metals enjoy premier status as heterogeneous catalysts as a result of their superlative properties. Yet for decades, researchers have sought to replace these costly metals with low-cost, Earth-abundant substitutes. Guided by computational methods for screening intermetallic compounds of common elements, Marc Armbrüster of the Max Planck Institute for Chemical Physics of Solids, in Dresden, Germany, and coworkers identified Al₁₃Fe₄ as an active and selective catalyst for semihydrogenation of acetylene. That reaction plays a key preparatory role in ethylene polymerization by removing (hydrogenating) trace levels of acetylene, a catalyst poison, from ethylene supplies. The team reports that Al₁₃Fe₄ remained active and stable during prolonged tests and converted acetylene to ethylene with selectivities comparable to commercial palladium-based catalysts. They note that the alloy, which consists of single Fe atoms encapsulated by an Al shell, is presently unoptimized, leaving open the possibility for further improvements by tailoring the particle size and selecting a customized support material.