Interaction of N2O (as gas dope) with nickel molybdate catalysts during the oxidative dehydrogenation of propane to propylene

Highly Efficient Fe-silicalite Zeolite in Direct Propane Ammoxidation with N2O and O2

“…It can be postulated that in a mixture of oxidants, the oxidation state of the active iron sites can be varied to achieve higher ACN and AcCN yields. A similar concept has been proposed to explain the positive effect of N 2 O in the oxidative dehydrogenation of propane with O 2 over nickel molybdate catalysts [22]. In any case, the positive effect of O 2 in the N 2 O-mediated propane ammoxidation over Fe-silicalite is exceptional attending to selective oxidations over iron zeolites.…”

Direct ammoxidation of propane over zeolites with traces of iron

“…This cooperative effect is not yet entirely understood. Pe´rez-Ramı´rez et al [11] proposed an explanation of the positive effect of N 2 O by changes in the oxidation state of the active iron sites in parallel with the case of nickel molybdate catalysts [27]. In addition to the synergy effect, the stability of the catalyst performance in time on stream is another great advantage of the direct propane conversion to acrylonitrile over steam-activated Fe-silicalites with the mixture of oxygen and nitrous oxide (see figure 2) in comparison with the propane conversion to propene in oxidative dehydrogenation over the same catalyst where the Fe-silicalites rapidly lost their activity due to coke formation [19].…”

Modulation of selective sites by introduction of N2O, CO2 and H2 as gaseous promoters into the feed during oxidation reactions

“…Homogeneous gas phase conversion of propane was not observed for any set of catalytic conditions of reaction described. No limitation by intraparticles gas diffusion of reactants was observed [4,5].…”

“…It was also previously demonstrated that the addition of 300 ppm N 2 O modifies the catalytic performances of the same catalyst in the same reaction by, principally: (i) decreasing the conversion of propane and oxygen, (ii) increasing the yield and the selectivity to propylene, and (iii) decreasing the yield and the selectivity to CO 2 [5]. In the presence of N 2 O, catalytic sites work in a more reduced state and, consequently, in a more selective way.…”

“…Previously [4][5][6][7], we reported the effects brought about by the introduction of CO 2 or N 2 O as gaseous additives during the oxidative dehydrogenation of propane (ODP) to propylene using NiMoO 4 alone or in mixture with a-Sb 2 O 4 as catalysts. With respect to the results obtained in the absence of CO 2 , the main consequences of the addition of CO 2 in the gas feed were: (i) an increase in the conversion of propane, (ii) a decrease in the yield and selectivity of propylene, and (iii) an increase of the CO 2 yield.…”