Nonoxidative and oxidative dehydrogenation of ethylbenzene over ZnFeCr ternary spinel system

Jebarathinam, N. John; Eswaramoorthy, M.; Krishnasamy, Vengaimuthu

doi:10.1016/0926-860x(96)00149-4

Cited by 26 publications

(13 citation statements)

References 15 publications

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“…Conversion of n-butene ¼ moles of n-butene reacted moles of n-butene supplied Selectivity for 1,3-butadiene [26]. Three types of spinel structures (normal spinel, inverse spinel, and random spinel) can be formed depending on the distribution of metal atoms; (i) a normal spinel structure in which divalent cations (A) are in the tetrahedral sites and trivalent cations (B) are in the octahedral sites, (ii) an inverse spinel structure in which divalent cations (A) occupy octahedral sites while trivalent cations (B) are equally distributed in the tetrahedral and octahedral sites, and (iii) a random spinel structure in which divalent (A) and trivalent cations (B) are randomly located at both tetrahedral and octahedral sites [7,27].…”

Section: Oxidative Dehydrogenation Of N-butenementioning

confidence: 99%

Effect of Divalent Metal Component (MeII) on the Catalytic Performance of MeIIFe2O4 Catalysts in the Oxidative Dehydrogenation of n-Butene to 1,3-Butadiene

et al. 2008

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A series of metal ferrite (Me II Fe 2 O 4 ) catalysts were prepared by a co-precipitation method with a variation of divalent metal component (Me II = Zn, Mg, Mn, Ni, Co, and Cu) for use in the oxidative dehydrogenation of n-butene to 1,3-butadiene. Successful formation of metal ferrite catalysts with a random spinel structure was confirmed by XRD, ICP-AES, and XPS analyses. The catalytic performance of metal ferrite catalysts in the oxidative dehydrogenation of n-butene strongly depended on the identity of divalent metal component. Acid properties of metal ferrite catalysts were measured by NH 3 -TPD experiments, with an aim of correlating the catalytic performance with the acid property of the catalysts. It was revealed that the yield for 1,3-butadiene increased with increasing surface acidity of the catalyst. Among the catalysts tested, ZnFe 2 O 4 catalyst with the largest surface acidity showed the best catalytic performance in the oxidative dehydrogenation of n-butene.

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Section: Oxidative Dehydrogenation Of N-butenementioning

confidence: 99%

Effect of Divalent Metal Component (MeII) on the Catalytic Performance of MeIIFe2O4 Catalysts in the Oxidative Dehydrogenation of n-Butene to 1,3-Butadiene

et al. 2008

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“…Cerium oxide was found to be the best promoter for accelerating styrene formation. Jebarathinam et al [8] demonstrated that the desorption of styrene was the rate-determining in the case of a catalyst of weak basicity; the formation of styrene was the rate-determining for a catalyst of weak acidity. Zhu et al [9] investigated transient kinetic experiments for Fe-K catalyst by on-line mass spectroscopy, and they revealed that the initial high activity for the dehydrogenation of ethylbenzene was originated from the fully oxidized iron (Fe 3+ ), and subsequently the yield of styrene decreased due to the reduction of iron.…”

Section: Introductionmentioning

confidence: 98%

High Performance of Fe–K Oxide Catalysts for Dehydrogenation of Ethylbenzene to Styrene with an aid of ppm-order Pd

et al. 2008

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Styrene is manufactured industrially through catalytic dehydrogenation of ethylbenzene on Fe-K oxidebased catalysts. It was invented by Süd-Chemie Group that the activity of the industrial ethylbenzene dehydrogenation catalysts (Styromax) based on the oxides of Fe and K is highly promoted by the addition of small amount (hundreds ppm-order) of precious metals such as Pd. The present work is intended to elucidate the role of Pd on the Fe-K catalyst empirically by use of a periodical pulse technique from a mechanistic point of view. The oxidative dehydrogenation was faster than the simple dehydrogenation, and it proceeded by consuming the surface lattice oxygen in the catalyst. The lattice oxygen was subsequently supplied from steam. Palladium added to the Fe-K oxide catalysts was found to enhance the rate of regeneration (supplying) of the lattice oxygen, although it hardly changed the rate of dehydrogenation of ethylbenzene or consumption of surface lattice O 2-anions. This study demonstrated that steam works not only as a diluent but also as a reactant to form hydrogen and lattice oxygen.

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“…2, which exhibit typical reflections of (220), (311), (222), 40 50 60 70 80 0 20 40 60 80 10 20 30 40 50 60 70 80 The average crystal size is determined by Scherrer equation using the peak broadening (FWHM) of the most intense peak (311): t = 0.9λ/βcos θ; where λ is the wavelength of CuKα (1.54059 Å), θ is the angle of Bragg diffraction at full width half maximum (FWHM). The average crystallite size obtained for all the spinel ferrites are given in Table-1.The cation distribution at A and B sites are determined by X-ray intensity calculations following the method reported by Jebarathinam et al [16].…”

Section: Resultsmentioning

confidence: 99%

Characterization and Magnetic Behaviour of Nanosized Binary Spinel Ferrites Synthesized by Low Temperature Hydrothermal Method and their Stability in Aqueous Suspensions

Ammal¹,

Jebarathinam²,

Jayalakshmi³

2017

Asian J. Chem.

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INTRODUCTIONFerro spinel compounds possess high permeability so that they can be used in electronics [1][2][3], in microwave and high density information storage devices [4], as ferrofluids [5] and magnetic drug delivery materials [6], etc. Spinel ferrites, possessing cubically close packed array of oxygen anions with the metallic ions occupy two crystallographically different sites, i.e. octahedral [B] and tetrahedral (A) site. Three kind of magnetic interactions are possible, between metallic ions, through the intermediate O ions, by super-exchange mechanism, namely, A-A interaction, B-B interaction and A-B interaction. It has been established experimentally that these interaction energies are negative and hence induce an anti-parallel orientation.Due to the specific electronic configurations of cations and the types of super-exchange interactions among them, the magnetic properties of ferrites are strongly dependent on the occupancy and exchange of cations in the two sites. In spinel ferrites, direct interactions are negligible, due to the large distance between cations. Super-exchange interaction occurs between two metal cations through the existence of a bridging oxygen ion. It involves the temporary transfer of one oxygen 2p electron to a neighboring metal ion. The A-B interaction is the strongest super-exchange interaction in the spinel structure, followed Cobalt ferrite, nickel ferrite and zinc ferrite spinel oxides are synthesized by low temperature hydrothermal method using ethylenediamine tetracetic acid (EDTA) as complexing agent. FTIR and XRD studies show the formation of pure and single spinel phase. The average crystalline size was determined from X-ray diffraction line broadening using Scherrer equation. FE-SEM studies revealed that all the synthesized ferrites are having nearly octahedron crystals with an average particle size of 20 to 40 nm. Magnetic behavior of cobalt ferrite, nickel ferrite and zinc ferrite spinels studied by vibrating sample magnetometer at room temperature shows ferromagnetic behaviour of cobalt ferrite, super paramagnetic nature of nickel ferrite and non-magnetic behaviour of zinc ferrite. Zeta potential measured at various pH conditions shows that cobalt ferrite and nickel ferrite can be used for the preparation of magnetic nanofluids with stable colloidal dispersion at 4.5 > pH < 7.5 and 3.5 > pH < 9.5, respectively.

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Nonoxidative and oxidative dehydrogenation of ethylbenzene over ZnFeCr ternary spinel system

Cited by 26 publications

References 15 publications

Effect of Divalent Metal Component (MeII) on the Catalytic Performance of MeIIFe2O4 Catalysts in the Oxidative Dehydrogenation of n-Butene to 1,3-Butadiene

Effect of Divalent Metal Component (MeII) on the Catalytic Performance of MeIIFe2O4 Catalysts in the Oxidative Dehydrogenation of n-Butene to 1,3-Butadiene

High Performance of Fe–K Oxide Catalysts for Dehydrogenation of Ethylbenzene to Styrene with an aid of ppm-order Pd

Characterization and Magnetic Behaviour of Nanosized Binary Spinel Ferrites Synthesized by Low Temperature Hydrothermal Method and their Stability in Aqueous Suspensions

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