Fig. 1: Copper templated zeolite mordenite exhibits the same active site identity as metalloenzyme methane monooxygenase. Ref: https://doi.org/10.1021/acs.jpcc.1c10774

Zeolite catalysts inspired by metalloenzymes

"Over the past several decades, isolated transition metal active sites have been stabilized in zeolite frameworks. Simultaneously, metalloenzyme active sites have been discovered, synthesized, or evolved for a variety of catalytic purposes. Recently, the structural similarity of copper/iron active sites in zeolites (fig. 1) and enzymes have received significant attention for the partial oxidation of hydrocarbons and for the remediation of harmful nitrogen oxides. These comparisons bring to light a significant opportunity and scientific challenge — to translate the earth-abundant active sites found in nature to industrially relevant heterogeneous catalysts. We assert that the similarity between metalloenzymes and metallozeolites is not limited to copper and iron catalysts."

Crustal abundance of catalytic materials

"No naturally occurring metalloenzymes utilize the platinum group metals. Contrastingly, many industrial processes rely on the platinum group metals as they tend to offer ideal reactivity. The platinum group metals are scarce and rapidly diminishing in crustal abundance (fig. 2). Metalloenzymes, however, have found powerful solutions to challenging reactions with earth-abundant transitions metals. Seeking replacement catalysts inspired by biological or evolved enzymes provides a future direction for rational catalyst design."

Fig. 2: The abundance of transition metal elements roughly correlates with their appearance in metalloenzymes. Contrastingly, metals with characteristically high activity are found at much lower concentrations. Ref: USGS Fact Sheet 087-02

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