In the quest to save money and prevent waste when making chemicals for industrial and consumer applications, laboratory chemists are looking to a new generation of catalysts to speed up reactions with less mess. Catalysts are added to chemical reactions to help efficiently transform raw materials into products. In a recent advance, researchers report how silver placed in a specific pattern on a stable molecular nanostructure can act as a catalyst and promote reactions at low temperatures using safe and abundant materials like oxygen in the reaction. The new system is 10 times more efficient than previous attempts. It not only conserves resources, but it will help researchers better understand how to use oxygen in industrial applications. The silver-based catalyst converts oxygen from the air into a chemically reactive form that allows common industrial chemicals to be made more efficiently. The products of these reactions are the starting materials for a majority of chemical products. Unlike previous catalysts that promote chemical reactions with oxygen, this silver-based model performs very well at low temperatures. Temperature is a key consideration. Lower temperatures reduce the amount of energy and potentially the cost of running these important reactions. The new catalyst created by researchers in China represents a 10-fold improvement over previous methods for making these chemical products. Catalysts increase the speed of chemical reactions. Yet they are not affected in the process. This allows catalysts to be reused and has helped expand their use in a wide range of manufacturing applications. In addition to working at low temperatures, the catalyst uses oxygen as the only additional reactant. Traditionally oxidation reactions have used harsh chemicals and generated large quantities of hazardous waste. In this reaction the oxygen is incorporated into the product without producing any additional waste. The results will help chemists understand how to better activate oxygen. Oxygen is often slow to react with other molecules because the molecule is very stable. It is usually found as two atoms paired together, hence its chemical nickname O2. These pairs must be broken apart before the individual oxygen atoms can react with other chemicals. The new catalyst breaks the oxygen atoms apart. It uses individual silver atoms located near a surface that does not have oxygen as part of its molecular structure. Using advanced chemical analysis tools, the scientists precisely characterised and explained the reactivity of the silver atoms that are attached to the surface of manganese oxide particle support. They verified the structure of their active catalyst with advanced microscopy and X-ray scattering techniques. The catalyst is only in the development stages. Before it is ready for use in the chemical industry, chemists will need to show that it can perform oxidation reactions cheaply on a wide range of organic molecules.
Environmental Health News, 10 July 2012 ;