Conversion of Nitrogen Dioxide, Nitric Acid, and

Abstract

A new technlque Is described for the real-tlme, quantltatlve conversion of several XNO, compounds to NO, where X de- notes a radical group. The technlque utlllzes the reductlon of these compounds by CO at a heated gold catalyst to yleld NO. The NO product was detected by a sensltlve chemllu- mlnescence detector. The technlque was demonstrated to convert NO,, HNO,, and n-propyl nltrate quantltatlvely to NO for mlxlng ratios In the range of 1-120 ppbv In synthetlc alr at atmospherlc pressure. Converslon results were obtained for CO mlxlng ratlos In the range of 0.2-1000 ppmv and for temperatures In the range of 20-600 OC. The Gormley- Kennedy equatlon was used to analyze the results for con- sistency with known dlffuslon coefflclents. The CO reductlon process Is dlscussed In terms of the thermochemistry of the net converslon reactlons and catalytlc properties of the gold surface. In addltlon, the potential of thls technlque for at- mospheric measurements Is noted.