SusChEM: Non-precious metal substitution into hydrogenation metal alloy catalysts deposited onto redox active supports for facile nitrate destruction in drinking water

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United States companies spend almost $3 billion a year buying and making reduction catalysts to help create fuel, fertilizers, and medicines. Given this investment and proven success, it is perhaps surprising that these catalysts are not used to produce potable drinking water. Instead, current drinking water treatment methods are costly and have potential to harm the environment. The main reason reduction catalysts are not used to clean water is because they are made from precious metals that also have a high cost, and water is a low value product. The research goal of this work is to advance the science of water treatment by replacing precious metals with inexpensive metal reduction catalysts to achieve treatment goals at the lowest cost and with the least harm to the environment. The catalysts will be used to treat nitrate, the most common groundwater pollutant in the world that results primarily from agricultural fertilizer. Student researchers will be trained to become future leaders in this technology, so they can train others to design more effective water treatment plants.The primary goal of the proposed work is to advance the science of supported metal-alloy catalysis for the treatment of the ubiquitous water pollutant nitrate. The specific objectives are to 1) develop new metal alloy nanoparticle catalysts with markedly higher catalytic activity for nitrate reduction; 2) identify electronically active supports that enhance catalytic activity and stability of alloy metal nanoparticles for water treatment; and 3) evaluate the environmental impacts and costs of the new catalysts using life cycle assessment. To address these objectives, a suite of platinum group metal-based alloy nanoparticles with lattice substituted semi- and non-precious metals will be synthesized using a novel microwave-assisted method. The catalysts will be supported on a series of redox active supports and characterized using advanced microscopic/spectroscopic techniques. The new catalysts will be evaluated with/without amended indium for nitrate and nitrite reduction kinetics, and selectivity for ammonia. The results will be compared to catalyst properties and interpreted with density functional theory to identify controlling mechanisms. Long-term catalyst stability will be evaluated under realistic water treatment conditions, and the results used to perform economic and environmental life cycle assessments. The proposed work will result in new fundamental knowledge regarding 1) the effects of hydrogenation-inactive metals on catalysis; 2) the influence of redox active supports on alloy metal alloy nanoparticle activity and stability; and 3) a quantitative assessment of the effects of metal alloys on cost and sustainability of catalytic treatment of drinking water.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.