1. CHEMISTRY 2000 Topics of Interest #8: “Green” Crystals – Cleaning up N 2 O Emissions

2. “Laughing Gas” is No Laughing Matter Nitrous oxide (N 2 O; colloquially known as “laughing gas”) is a greenhouse gas emitted by many chemical plants. As well as contributing to climate change, it also reacts with the ozone layer. Researchers recently developed technology to remove N 2 O from chemical plant exhausts as it is emitted: The exhausts are passed over a catalytic membrane which converts the N 2 O into N 2. As an added bonus, the oxygen atoms from N 2 O are used to convert CH 4 into “synthesis gas”, a mixture of H 2 and CO that can be used to make a wide variety of chemicals. Effectively, the waste N 2 O is “recycled” rather than emitted. H. Jiang et al Angew. Chemie Int. Ed. (2009) DOI: 10.1038/457639d. As reported in Nature (2009) 457 p. 639

3. “Laughing Gas” is No Laughing Matter The membrane consists of a crystal lattice containing barium, cobalt, iron, zirconium and oxygen atoms (BaCo x Fe y Zr [1-(x+y)] O 3-  ). It takes the form of hollow fibres that exhausts can be passed through: H. Jiang et al Angew. Chemie Int. Ed. (2009) 48 pp. 1-5. As reported in Nature (2009) 457 p. 639

4. “Laughing Gas” is No Laughing Matter This is an example of how we can use oxidation-reduction chemistry (or “redox” chemistry) to our advantage. The oxidation half-reaction produces “synthesis gas” from methane and oxide ions while the reduction half-reaction breaks the undesirable N 2 O into harmless N 2 gas and more oxide anions: Gas mixtures containing as much as 50% N 2 O reacted fully with the membranes. H. Jiang et al Angew. Chemie Int. Ed. (2009) 48 pp. 1-5. As reported in Nature (2009) 457 p. 639 reduction oxidation