Oxidative dehydrogenation of C3–C4 paraffins in the presence of CO2 over CrOx/SiO2 catalysts

Botavina, Maria; Martra, Gianmario; Agafonov, Yu. A.; Gaidai, N. A.; Nekrasov, N. V.; Trushin, D.V.; Coluccia, S.; Лапидус, А. Л.

doi:10.1016/j.apcata.2008.05.037

Cited by 58 publications

(47 citation statements)

References 39 publications

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“…For direct reduction, the C−H bonds in the organics could easily react with Cr(VI) and subsequently reduce it. 30,31 The carbonyl products were formed after C−H bonds reacted with Cr(VI). 32,33 In the indirect reduction, the secondary cracking of the volatile organics could form new products, which could react with Cr(VI).…”

Section: ■ Results and Discussionmentioning

confidence: 99%

Pyrolysis Treatment of Chromite Ore Processing Residue by Biomass: Cellulose Pyrolysis and Cr(VI) Reduction Behavior

Zhang

et al. 2016

Environ. Sci. Technol.

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ABSTRACT:The pyrolysis treatment with biomass is a promising technology for the remediation of chromite-oreprocessing residue (COPR). However, the mechanism of this process is still unclear. In this study, the behavior of pyrolysis reduction of Cr(VI) by cellulose, the main component of biomass, was elucidated. The results showed that the volatile fraction (VF) of cellulose, ie. gas and tar, was responsible for Cr(VI) reduction. All organic compounds, as well as CO and H 2 in VF, potentially reduced Cr(VI). X-ray absorption nearedge structure (XANES) spectroscopy and extended X-ray absorption fine-structure (EXAFS) spectroscopy confirmed the reduction of Cr(VI) to Cr(III) and the formation of amorphous Cr 2 O 3 . The remnant Cr(VI) content in COPR can be reduced below the detection limit (2 mg/kg) by the reduction of COPR particle and extension of reaction time between VF and COPR. This study provided a deep insight on the co-pyrolysis of cellulose with Cr(VI) in COPR and an ideal approach by which to characterize and optimize the pyrolysis treatment for COPR by other organics.

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Section: ■ Results and Discussionmentioning

confidence: 99%

Pyrolysis Treatment of Chromite Ore Processing Residue by Biomass: Cellulose Pyrolysis and Cr(VI) Reduction Behavior

Zhang

et al. 2016

Environ. Sci. Technol.

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“…that is almost equal to the propane conversion that can be achieved on the catalyst with 5.0 wt% Cr but prepared by standard method of wet impregnation (47%) [5]. Propane conversion increased with the increase of chromium loading and on the catalyst with 6.0wt% of chromium attained 85%.…”

Section: ------------------------------------------------------------mentioning

confidence: 60%

“…For the sake of comparison, the values for the catalysts prepared by wet impregnation method (hereafter: Cr-SiO 2 -WI) are also reported [5] (Table 1, Part B). It can be observed, that the two types of catalysts with the similar chromium loadings exhibit similar textural features.…”

Section: Page 5 Of 21mentioning

confidence: 99%

“…For the sake of comparison, the spectra of the catalysts, prepared by wet impregnation (Figure 3, panel B) and the spectrum of the bare silica KSKG (Figure 3, panel B, curve 1) are also reported [5].…”

Section: Page 7 Of 21mentioning

confidence: 99%

“…Among these latter is the oxidative dehydrogenation of propane (ODH), where O2, CO2 or a CO2+O2 mixture can be used like an oxidant agents [5][6][7][8][9][10][11][12][13][14]. Actually, this process has been the subject of many investigations, and a number of catalysts has been evaluated [15].…”

Section: Introductionmentioning

confidence: 99%

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CrO /SiO2 catalysts prepared by metal vapour synthesis: Physical–chemical characterisation and functional testing in oxidative dehydrogenation of propane

Botavina¹,

Evangelisti²,

Agafonov³

et al. 2011

Chemical Engineering Journal

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In the present work catalysts prepared by a new perspective method of metal vapour synthesis were studied in the reaction of propane oxidative dehydrogenation in the presence of CO 2 as a mild oxidant. This method let to obtain on the catalyst surface a high dispersed chromium species even at high chromium loadings. On the surface of the catalysts with the chromium loading up to 6.0 wt % only chromate species were found, the further increase of the chromium loading results in the appearance of the -Cr 2 O 3 . The catalyst with 6.0 wt % demonstrated also the highest catalytic activity with the yield in propene 69%.

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Promotional Effect of Ni on a CrO_x Catalyst Supported on Silica in the Oxidative Dehydrogenation of Propane with CO₂

et al. 2012

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As CrOx catalysts supported on the SBA‐15 support (Cr/Si) are highly active, they represent potentially promising catalysts for the oxidative dehydrogenation of propane with CO2 (ODHP). However, reduction of the active sites (Cr3+) during the reaction is known to lead to severe deactivation. The findings reported herein indicate that after the addition of 0.5 wt % Ni to 10 wt % Cr/Si (0.5 Ni‐Cr/Si), the catalytic activity was stable and the selectivity was high. Reduced CrOx was easily regenerated by the addition of Ni, as evidenced by a three‐step H2‐temperature programmed reduction analysis. In addition, ex situ XPS results revealed that Cr3+ was maintained only in the Ni‐promoted catalyst whereas Cr3+ was easily reduced to Cr2+ in the non‐promoted catalyst during the reaction. The role of the Ni added to the catalyst elucidates that Ni induces the dissociation of CO2 to CO and activated O (O*ads). Then, the generated O*ads regenerates the reduced CrOx. Consequently, the Ni‐promoted Cr/Si catalyst enhances the catalytic stability of propylene in the ODHP reaction.

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Oxidative dehydrogenation of C3–C4 paraffins in the presence of CO2 over CrOx/SiO2 catalysts

Cited by 58 publications

References 39 publications

Pyrolysis Treatment of Chromite Ore Processing Residue by Biomass: Cellulose Pyrolysis and Cr(VI) Reduction Behavior

Pyrolysis Treatment of Chromite Ore Processing Residue by Biomass: Cellulose Pyrolysis and Cr(VI) Reduction Behavior

CrO /SiO2 catalysts prepared by metal vapour synthesis: Physical–chemical characterisation and functional testing in oxidative dehydrogenation of propane

Promotional Effect of Ni on a CrO_x Catalyst Supported on Silica in the Oxidative Dehydrogenation of Propane with CO₂

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Oxidative dehydrogenation of C3–C4 paraffins in the presence of CO2 over CrOx/SiO2 catalysts

Cited by 58 publications

References 39 publications

Pyrolysis Treatment of Chromite Ore Processing Residue by Biomass: Cellulose Pyrolysis and Cr(VI) Reduction Behavior

Pyrolysis Treatment of Chromite Ore Processing Residue by Biomass: Cellulose Pyrolysis and Cr(VI) Reduction Behavior

CrO /SiO2 catalysts prepared by metal vapour synthesis: Physical–chemical characterisation and functional testing in oxidative dehydrogenation of propane

Promotional Effect of Ni on a CrOx Catalyst Supported on Silica in the Oxidative Dehydrogenation of Propane with CO2

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Promotional Effect of Ni on a CrO_x Catalyst Supported on Silica in the Oxidative Dehydrogenation of Propane with CO₂