Isobutane dehydrogenation on chromia/zirconia catalysts

Rossi, S. De; Ferraris, Giovanni; Fremiotti, Silvia; Indovina, Valerio; Cimino, A.

doi:10.1016/0926-860x(93)80160-r

Cited by 49 publications

(27 citation statements)

References 18 publications

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“…25−32 De Rossi et al reported that higher dehydrogenation activity was observed over ZrO 2 compared with SiO 2 as a catalyst support for chromium-catalyzed PDH. 33−36 However, the low surface area of ZrO 2 (<100 m 2 /g) 28,34,35 resulted in lower overall activity than on Al 2 O 3 . For the purpose of fundamental study in this work, there are a low number of hydroxyl groups on ZrO 2 , likely of many different types that strongly depend on dehydration conditions (cf.…”

Section: Introductionmentioning

confidence: 99%

Zirconium Modification Promotes Catalytic Activity of a Single-Site Cobalt Heterogeneous Catalyst for Propane Dehydrogenation

Zhao

Sohn

et al. 2018

ACS Omega

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The effect of Zr modification on the catalytic activity of Co/SiO 2 was investigated for nonoxidative propane dehydrogenation. Isolated Zr on SiO 2 surface sites were prepared by organometallic synthesis using Zr(O t Bu) 4 as a precursor. The resulting Zr/SiO 2 support was functionalized with Co 2+ ions via strong electrostatic adsorption. Spectroscopic (diffuse reflectance infrared Fourier transform spectroscopy, UV–vis, electron paramagnetic resonance) and microscopic characterization (transmission electron microscopy, scanning transition electron microscopy) results are consistent with single-site cobalt that preferentially associates with the mono-dispersed Zr at a variety of loadings and Co/Zr ratios. The oxidation state of Co in the as-prepared Co/SiO 2 and Co–Zr/SiO 2 was both +2 with tetrahedral and octahedral geometries, respectively. In situ X-ray absorption near edge structure and extended X-ray absorption fine structure results confirmed that the oxidation state of Co remained as +2 under reaction condition for both Co/SiO 2 and Co–Zr/SiO 2 samples and both catalysts have tetrahedral Co 2+ as the active catalyst. Despite similar Co coordination environments, the catalytic activity and selectivity was significantly improved by the Zr modification of the silica support versus Co/SiO 2 . This was attributed to the change in oxygen donor ability and Co–O bond strength of the ≡SiO–Zr–O sites of Co–Zr/SiO 2 compared with the ≡SiO– ligands in Co/SiO 2 . These results show that tuning of the support SiO 2 oxygen donation ability by use of an anchoring site (e.g., ≡SiO–Zr–O – ) can be used to alter both rate and selectivity of propane dehydrogenation with single-site heterogeneous catalysts. These results also show some preference for Co 2+ active sites to associate with ≡SiO–Zr–O – sites over ≡SiO–.

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Section: Introductionmentioning

confidence: 99%

Zirconium Modification Promotes Catalytic Activity of a Single-Site Cobalt Heterogeneous Catalyst for Propane Dehydrogenation

Zhao

Sohn

et al. 2018

ACS Omega

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“…(C) nm −2 . This is not enough to affect the activity so that conversions ( X ) and selectivities ( S ) were calculated on a molar basis neglecting coke. The activity of the catalysts is given as the rate of isobutene formation determined by Equation

r = \frac{X * S * F}{m_{cat}}

in which r is the rate of isobutene formation (μmol s −1 g cat −1 ), F is the molar isobutane flow (μmol s −1 ), and m cat is the weight of the catalyst (g cat ).…”

Section: Methodsmentioning

confidence: 99%

The Effect of Transition Alumina (γ‐, η‐, χ‐Al₂O₃) on the Activity and Stability of Chromia/Alumina Catalysts. Part I: Model Catalysts and Aging Conditions

et al. 2019

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The effect of transition alumina (γ‐, η‐, χ‐Al2O3) on the activity and stability of model chromia/alumina catalysts with 4 wt% Cr in isobutane dehydrogenation is studied. It is shown that a fresh catalyst with η‐Al2O3 as a support has the highest activity, while with χ‐Al2O3 has the lowest one. The characterization of the catalysts by N2 adsorption, X‐ray diffraction (XRD), electron spin resonance (ESR) spectroscopy, and X‐ray photoelectron spectroscopy (XPS) is used to describe changes in the catalysts induced by high‐temperature treatment at 800, 1000, and 1200 °C in air. It is shown that sintering of the alumina support and formation of chromia‐alumina solid solutions are the reasons of irreversible decline in the catalytic activity. Cr/γ‐Al2O3 is found to be the most stable to sintering and phase transformation, whereas Cr/χ‐Al2O3 is found to be the least stable. Due to its highest initial activity, the η‐Al2O3‐supported catalyst loses its dehydrogenation activity most rapidly as the calcination temperature is raised. The segregation of sodium impurities is observed in the course of heat treatment, which may be an additional cause of deactivation.

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“…␥-Alumina (grain size 100-500 m, surface area 121 m 2 g −1 , kindly provided by Süd Chemie MT, Novara, Italy) was obtained by calcination in air of pseudoboehmite Versal 250 La Roche at 1223 K for 4 h. The support was impregnated with comparable volumes of aqueous solutions of the appropriate amounts of CrO 3 (and K 2 Cr 2 O 7 for the ACr10KX samples). The carefully stirred paste was dried overnight at 383 K and finally calcined at 973 K for 12 h. For comparison purposes a sample of crystalline chromia was prepared as in [9]. All chemicals were Carlo Erba reagent grade.…”

Section: Catalyst Preparationmentioning

confidence: 99%

Catalytic nitroxidation of 1-methylnaphthalene

Rombi

Cutrufello

Rossi

et al. 2006

Journal of Molecular Catalysis A: Chemical

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Isobutane dehydrogenation on chromia/zirconia catalysts

Cited by 49 publications

References 18 publications

Zirconium Modification Promotes Catalytic Activity of a Single-Site Cobalt Heterogeneous Catalyst for Propane Dehydrogenation

Zirconium Modification Promotes Catalytic Activity of a Single-Site Cobalt Heterogeneous Catalyst for Propane Dehydrogenation

The Effect of Transition Alumina (γ‐, η‐, χ‐Al₂O₃) on the Activity and Stability of Chromia/Alumina Catalysts. Part I: Model Catalysts and Aging Conditions

Catalytic nitroxidation of 1-methylnaphthalene

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Isobutane dehydrogenation on chromia/zirconia catalysts

Cited by 49 publications

References 18 publications

Zirconium Modification Promotes Catalytic Activity of a Single-Site Cobalt Heterogeneous Catalyst for Propane Dehydrogenation

Zirconium Modification Promotes Catalytic Activity of a Single-Site Cobalt Heterogeneous Catalyst for Propane Dehydrogenation

The Effect of Transition Alumina (γ‐, η‐, χ‐Al2O3) on the Activity and Stability of Chromia/Alumina Catalysts. Part I: Model Catalysts and Aging Conditions

Catalytic nitroxidation of 1-methylnaphthalene

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The Effect of Transition Alumina (γ‐, η‐, χ‐Al₂O₃) on the Activity and Stability of Chromia/Alumina Catalysts. Part I: Model Catalysts and Aging Conditions