Behavior of active sites on Cr-MCM-41 catalysts during the dehydrogenation of propane with CO2

Takehira, Katsuomi; Ohishi, Yoshihiko; Shishido, Tetsuya; Kawabata, Tomonori; Takaki, Ken; Zhang, Qinghong; Wang, Ye

doi:10.1016/j.jcat.2004.03.014

Cited by 200 publications

(181 citation statements)

References 55 publications

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“…1). In accordance with the results of detailed studies by Takehira et al (2004) and Bensalem et al (1997), these bands were assigned to O-Cr(VI) electronic charge transfer of chromate species in a tetrahedral conformational structure.…”

Section: Uv-vis Spectrophotometric Titrationsupporting

confidence: 86%

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Soil humic acids may favour the persistence of hexavalent chromium in soil

Leita

Margon

Pastrello

et al. 2009

Environmental Pollution

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The interaction between hexavalent chromium Cr(VI), as K 2 CrO 4 , and standard humic acids (HAs) in bulk solution was studied using three complementary analytical methods: UV-Visible spectroscopy, X-ray absorption spectroscopy and differential pulse stripping voltammetry. The observed UV-Vis and X-ray absorption spectra showed that, under our experimental conditions, HAs did not induce reduction of Cr(VI) to its trivalent chemical form. The interaction between Cr(VI) and HAs has rather led to the formation of Cr(VI)-HAs micelles via supramolecular chemical processes. The reported results could contribute towards explaining the relative persistence of ecotoxic hexavalent chromium in soils.

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Section: Uv-vis Spectrophotometric Titrationsupporting

confidence: 86%

“…As comparatively shown in Fig. 1, we did not observe any absorption bands at 425 and 583 nm assigned to the typical octahedral Cr(III) structure (Takehira et al, 2004). The reduction of Cr(VI) is strongly pH-dependent.…”

Section: Uv-vis Spectrophotometric Titrationmentioning

confidence: 45%

Soil humic acids may favour the persistence of hexavalent chromium in soil

Leita

Margon

Pastrello

et al. 2009

Environmental Pollution

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“…The chromium species with the high oxidation state is found to play a key role in obtaining higher catalytic activity during the dehydrogenation of light alkanes [39,40]. Ge et al [11] used electron spin resonance and UV-DRS to explore the active site for the ODE with CO 2 over silica-supported chromium oxide catalysts and established that the species with a higher oxidation state (Cr 5? [41,42].…”

Section: Catalytic Activitymentioning

confidence: 99%

Oxidative dehydrogenation of ethane with carbon dioxide over Cr2O3/SBA-15 catalysts: the influence of sulfate modification of the support

et al. 2017

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Unmodified and sulfate-modified SBA-15-supported Cr 2 O 3 catalysts were prepared by impregnation method. The physico-chemical properties of the supports and catalysts were determined by nitrogen adsorption/ desorption, powder X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), laser-Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), UV-Vis diffuse reflectance spectroscopy (UV-DRS), inductively coupled plasma optical emission spectroscopy (ICP-OES), transmission electron microscopy (TEM) and temperature-programmed reduction (TPR) techniques. Oxidative dehydrogenation of ethane to ethylene (ODE) with CO 2 as oxidant was carried out on these catalysts in a fixed-bed reactor at temperatures in the range of 600-700°C and at atmospheric pressure. The changes in structural and textural properties because of sulfate modification were identified. Sulfate modification affected the nature of interaction of CrO x species with the SBA-15 support. During the evaluation, it was observed that sulfate modification enhances ethane conversion and ethylene selectivity of the catalyst. Better dispersion of CrO x and the increase in Cr 6? /Cr 3? ratio seem to be the reasons for the higher performance of the sulfate-modified catalysts compared to that of the unmodified catalyst.

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“…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%

“…The traditional preparation method based on wet impregnation is characterized by a low cost and operational easy, but it appeared unable to prevent the formation of agglomerated species and Cr 2 O 3 particles, that are less effective or even effective towards side reactions (e.g, total oxidation) respectively. Conversely, "one-pot" methods for the preparation of Cr/MCM-41 [9,10,16] and Cr/SBA-15 [17, 18] materials with highly isolated Cr species exposed at the inner wall of the channels of a silica regular mesoporous matrix have been developed, but Cr contents higher than 1 wt% usually resulted in the depletion of the mesoporous structure. Here, we report the possibility to prepare Cr/SiO 2 catalysts for ODH by using the so called "metal vapour synthesis (MVS) method".…”

Section: Introductionmentioning

confidence: 99%

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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Behavior of active sites on Cr-MCM-41 catalysts during the dehydrogenation of propane with CO2

Cited by 200 publications

References 55 publications

Soil humic acids may favour the persistence of hexavalent chromium in soil

Soil humic acids may favour the persistence of hexavalent chromium in soil

Oxidative dehydrogenation of ethane with carbon dioxide over Cr2O3/SBA-15 catalysts: the influence of sulfate modification of the support

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

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