Catalytic oxidation of propylene. 11. An investigation of the kinetics and mechanism over iron-antimony oxide

Keulks, George W.; Lo, M.-Y.

doi:10.1021/j100411a012

Cited by 31 publications

(22 citation statements)

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“…Because the selectivity to 1,3 butadiene increased, 2-butenal selectivity decreased and the other product selectivities remained constant with increasing space time, it can be concluded that 2-butenal can be converted in a secondary reaction step into 1,3-butadiene. The selectivity to 2-butene remains totally unchanged during the space time study which is to be expected on the basis of the findings of Adams [6] who showed that 0-olefins have a lower reactivity than the a-olefins. The amount of trans-2-butene in the fraction of 2-butene remained unchanged at 45% with both an increase of space time and of temperature.…”

Section: A Selection Of the Experimental Data Is Given Insupporting

confidence: 65%

“…The mechanism of the partial oxidation of propene to acrolein has been well studied. On the basis of deuterated propene studies, Keulks and Lo (6) showed for the selective oxidation of ethane, where the formation of a metal-allyl ether yields the selective partial oxidation products, whereas the formation of metal-alky 1 bond yields total oxidation (7). However, further investigation is necessary to proof this proposed reaction mechanism.…”

Section: Discussionmentioning

confidence: 99%

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Selective Partial Oxidation of α-Olefins over Iron Antimony Oxide

Steen

Schnobel

O’Connor

1996

ACS Symposium Series

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α-olefins in the range of ethene to 1-nonene were studied over an iron antimony oxide catalyst at temperatures between 350°C and 400°C in a tubular flow reactor. The primary reactions can be classified into five distinct classes, viz. double bond isomerization, partial oxidation, oxidative dehydrogenation, cracking and total oxidation. Ethene was unreactive and only total combustion products were formed. Propene and 1-butene formed conjugative aldehydes while 2-butenal produced 1,3 butadiene. On the basis of these results a mechanism for the partial oxidation and oxidative dehydrogenation of 1-butene is proposed. Increasing carbon number was found to increase the primary rate of total oxidation and the rate of formation of cracking products. Increasing carbon number decreased the rate of oxidative dehydrogenation and partial oxidation, except when going from C 3 to C 4 . The observed carbon number dependencies might be explained in terms of ease of formation and of stability of the π-allyl intermediate.Iron antimony oxide is a well known catalyst for the partial oxidation/ammoxidation of propene (1) and the oxidative dehydrogenation of n-butene (2). Aso et al.(3) studied iron antimony oxide containing various Sb:Fe ratios for the partial oxidation of propene. The activity and selectivity to acrolein increased strongly with increasing Sb contents beyond a ratio of 1:1. In a recent study of the surface properties of FeSb0 4 (4), it was concluded that the surface has a Sb-rich "skin" which is essential to the selective properties of the catalyst. Although iron antimony oxide is a well known catalyst for the selective oxidation of olefins, this catalyst is not selective for the partial oxidation of paraffins (van Steen, E.; Schnobel, M.; O'Connor, C. T., University of Cape Town, unpublished work).The partial oxidation of higher olefins has not been studied to the same extend as the oxidation of ethene, propene and butene. The dependency of the

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Section: A Selection Of the Experimental Data Is Given Insupporting

confidence: 65%

Section: Discussionmentioning

confidence: 99%

Selective Partial Oxidation of α-Olefins over Iron Antimony Oxide

Steen

Schnobel

O’Connor

1996

ACS Symposium Series

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“…Thus, in the process of propylene oxidation on a layered Bi molybdate, oxygen ions from up to 500 monolayers could participate in the reaction products formation [4]. At the same time, for catalysts with a low mobility of the lattice oxygen (V-P-O catalyst, Fe-Sb-O etc), only 2-3 near-surface layers are involved in reaction [5,6].…”

Section: Introductionmentioning

confidence: 99%

Effect of oxygen mobility in solid catalyst on transient regimes of catalytic reaction of methane partial oxidation at short contact times

et al. 2006

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Mathematical modeling of the effect of the oxygen mobility in a solid oxide catalyst on the dynamics of transients of fast catalytic reactions has been carried out. The analysis was based upon the redox mechanistic scheme with a due regard for diffusion of oxygen from the bulk of catalyst to its surface. Parameters of kinetic and mathematical models were selected via fitting of the experimental data for methane selective oxidation into syngas on 1.4%Pt/Gd 0.2 Ce 0.4 Zr 0.4 O x catalyst. The range of the Thiele parameter (/) where the oxygen bulk diffusion affects the most strongly reaction transients corresponds to /2[0:3 Ä 7]. For highsurface-area oxide catalysts, the bulk oxygen diffusion coefficients corresponding to this range of the Thiele parameter are in the range of10 À18 Ä 10 À13 cm 2 /s.

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“…Thus, in the oxidation of propylene at bismuth molybdate, which has a layer structure, oxygen ions of 500 monolayers in number can take part in the formation of the reaction products [2]. At the same time at catalysts with nonmobile volume oxygen (phosphorus-vanadium, iron-antimony, and others) the oxygen of~2-3rd surface layers enter into the reaction [3,4].The oxide catalysts of oxidation processes include catalysts based on perovskites. In [5] it was shown that in the series of modified perovskite catalysts SrCoO 3 a system with the composition K 0.125 Na 0.125 Sr 0.75 CoO 3-x exhibits the highest activity and selectivity in conjunction with stability of catalytic action in the condensation of methane in the gas phase in the absence of oxygen.…”

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confidence: 99%

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Effect of the mobility of oxygen in perovskite catalyst on the dynamics of oxidative coupling of methane

2011

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The effect of the diffusion of oxygen from the volume of the catalyst to its surface on the dynamics of the oxidative coupling of methane was assessed on the basis of a mathematical model of the reaction of methane with the oxidized surface of KNaSrCoO 3-x perovskite. It was shown that the possible values of the diffusion coefficient lie in the range of 10 -18 -10 -16 cm 2 /s characteristic of the diffusion of oxygen in oxide catalysts.Key words: diffusion of oxygen, mathematical modeling, perovskite, oxidative coupling of methane.The diffusion of ions and atoms in the crystal lattice of solids takes place as a result of the movement of point defects. The diffusion process can be realized by various mechanisms depending on the type of defect: exchange of the atoms of the crystalline structure with its vacancies, movement of the atoms along the interstices, simultaneous cyclic replacement of several atoms, etc.[1]. The diffusion effect in a solid catalyst is widely distributed and has a significant effect on the course of the catalytic reactions. This mostly concerns the diffusion of oxygen in metal oxides.Most oxidation processes are realized in the presence of oxygen in the gas phase. Nevertheless there are processes that are preferably realized in a nonstationary regime where the catalyst is alternately oxidized and reduced.The degree of participation of the oxygen of the catalyst is determined by its mobility in the volume of the crystal lattice and the capacity characteristics of the catalyst with respect to oxygen. Thus, in the oxidation of propylene at bismuth molybdate, which has a layer structure, oxygen ions of 500 monolayers in number can take part in the formation of the reaction products [2]. At the same time at catalysts with nonmobile volume oxygen (phosphorus-vanadium, iron-antimony, and others) the oxygen of~2-3rd surface layers enter into the reaction [3,4].The oxide catalysts of oxidation processes include catalysts based on perovskites. In [5] it was shown that in the series of modified perovskite catalysts SrCoO 3 a system with the composition K 0.125 Na 0.125 Sr 0.75 CoO 3-x exhibits the highest activity and selectivity in conjunction with stability of catalytic action in the condensation of methane in the gas phase in the absence of oxygen. In this case the reaction products are formed as a result of reaction of the methane with oxygen on the surface of the catalyst; the decrease of surface oxygen is partly compensated as a result of its diffusion from the volume of the catalyst.It is clear that the effect of the volume oxygen will be minimal if the diffusion is too low. In this connection it seemed of interest to obtain a quantitative estimate of the range of diffusion coefficients of oxygen in the volume of the catalyst in order to 0040-5760/11/4701-0049

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Catalytic oxidation of propylene. 11. An investigation of the kinetics and mechanism over iron-antimony oxide

Cited by 31 publications

References 0 publications

Selective Partial Oxidation of α-Olefins over Iron Antimony Oxide

Selective Partial Oxidation of α-Olefins over Iron Antimony Oxide

Effect of oxygen mobility in solid catalyst on transient regimes of catalytic reaction of methane partial oxidation at short contact times

Effect of the mobility of oxygen in perovskite catalyst on the dynamics of oxidative coupling of methane

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