Sorption–desorption of NOx from a lean gas mixture on H3PW12O40 · 6H2O supported on carbon nanotubes

NO x sorption capacities and efficiencies were measured on a new type of sorbent formed by 12-tungstophosphoric acid (HPW) supported on carbon nanotubes. On such a system, the sorption of both NO and NO2 was observed but compared with HPW alone, a complementary sorption of NO x is possible leading to a capacity of 25 mg/gHPW at 300 °C with an efficiency of 50%. The sorption results from the formation of a [H+(NO2 −),NO+)]. complex on HPW and an additional mode of adsorption by a free-nitrate which was identified by the bands at 2261, 1384 and 1295 cm−1 using infrared spectroscopy.