Hydrogenation metal-based catalytic processes have emerged as a promising alternative to traditional zero-valent Fe for selective reductive transformation of water contaminants (e.g., halocarbons, nitro explosive, and oxyanions). Particularly, palladium-based catalysts have demonstrated their superior performance and stability in both lab- and pilot-scale studies. However, the scarcity and the high cost of Pd and its poor activity for certain contaminants necessitate an expansion of the catalyst toolbox. We have discovered that commercial Ru catalysts are very active in reducing nitrate and nitrite, among the most ubiquitous groundwater contaminants. This is relevant because Ru is much less expensive than Pd. The rapid conversion of nitrate and its postulated reduction intermediate, nitrous oxide, prompted the hypothesis that Ru is potentially effective for catalyzing the reduction of other water contaminants containing nitro or nitroso functional groups. This presentation will focus on our most recent finding of Ru/Al2O3 being highly reactive with N-nitrosamines. N-nitrosodimethylamine (NDMA) was selected as a model N-nitrosamine to evaluate catalyst activity and characterize reaction kinetics and products. A mixture of N-nitrosamines was used to demonstrate catalyst efficiency for various N-nitrosamine structures at environmentally relevant concentrations. The extremely high activity of Ru for catalyzing the reduction of N-nitrosamines provides evidence for the abovementioned hypothesis. To further explore the strength of Ru catalysts in water purification and remediation, we also tested commercial Ru/Al2O3 and Pd/Al2O3 for a suit of contaminants featuring a variety of reducible functional groups.

Expanding the catalyst toolbox – low-cost ruthenium catalysts for reduction of water contaminants

255th National Meeting (2018)

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