Oxidation of propane with oxygen, nitrous oxide and oxygen/nitrous oxide mixture over Co- and Fe-zeolites

Oxygen, nitrous oxide and their mixture was used in oxidation of propane over CoH(Fe)-BEA and parent H(Fe)-zeolites (containing trace concentrations of Fe) of beta and ZSM-5 structures. CoH(Fe)-BEA zeolite exhibited a substantial increase in propene yield (from 2.0 to 6.8%), if together with molecular oxygen, nitrous oxide was used. No other oxygenates were detected. With increasing concentration of molecular oxygen in the propane/nitrous oxide/oxygen mixture, a synergetic effect of oxygen and nitrous oxide resulting in nearly threefold increase in propene yield was observed. At the reaction conditions studied, the highest propane conversion (15.8%) with 61.9% selectivity to propene and propene yield of 9.8%, and the sum of selectivities to oxygenates of 10.3% (foremost propyl alcohol and propanal) was achieved with the steamed H(Fe)-MFI zeolite when a mixture of nitrous oxide and oxygen was used. It is concluded that, the oxidation activity of nitrous oxide originates from specific Fe species, present in CoH(Fe)-BEA and H(Fe)-zeolites, exhibiting extra-ordinary activity in hydroxylation of propane to propyl alcohol (dehydrated to propene) and its further oxidation to propanal, whereas Co ions contribute only to propane oxidation to propene and carbon oxides.