Oxygenates from light alkanes catalyzed by NOx in the gas phase

The partial oxidations of light alkanes (methane, ethane, propane, and iso-butane) catalyzed by NOx in the gas phase have been studied at a pressure of less than 1 bar. For all the alkanes tested, the addition of NO to the mixture of alkanes and O-2 enhanced the selectivities and the yields of oxygenates remarkably. It was suggested that NO2 generated from NO and O-2 initiated the oxidation of alkanes and would specifically accelerate the C-C bond fission, enhancing the formation of C-1-oxygenates from ethane, propane, and iso-butane. NO2 and NO could be used as a homogeneous catalyst at >600 degrees C because nitroalkanes formed were decomposed completely, releasing the NOx. The comparison of the product distributions for the decomposition and oxidation of nitroalkanes and alkylnitrites strongly suggested that the oxygenates (HCHO, CH3CHO, and CH3COCH3) were formed from the corresponding alkylnitrites which must be the reaction intermediates during the oxidation of alkanes with an O-2 and NO mixture. (C) 1999 Academic Press.