Catalytic oxidation of chlorinated benzenes over V2O5/TiO2 catalysts

Lichtenberger, Janine

doi:10.1016/j.jcat.2004.01.032

Cited by 307 publications

(201 citation statements)

References 39 publications

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“…According to previous studies, the band at 1,716 cm -1 is assignable to C=O stretching vibration of acetate species [31]. The peaks at 1,575 and 1,439 cm -1 are explained by the contribution of C=C stretching vibrations of phenolate species [28,32,33]. Phenolate and acetate species are the partial oxidation products when HCB are decomposed, whose appearance provides the proof for the oxidative degradation of HCB.…”

Section: Resultsmentioning

confidence: 76%

“…Stach [9] and Weber [23] et al demonstrated that hydrodechlorination existed, when polychlorinated aromatics was decomposed by different metal oxides. Krishnamoorthy [24][25][26], Liu [27] and Lichtenberger [28] et al considered that catalytic oxidation was the reaction pathway, when polychlorinated aromatics was decomposed by oxide catalysts.…”

Section: Introductionmentioning

confidence: 99%

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Competitive Reaction During Decomposition of Hexachlorobenzene Over Ultrafine Ca–Fe Composite Oxide Catalyst

Sun

et al. 2007

Catal Lett

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The decomposition of hexachlorobenzene (HCB) has been investigated over ultrafine Ca-Fe composite oxide catalyst (Ca/Fe atomic ratio was 3.4), CaO and a-Fe 2 O 3 by using in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS). Adsorption experiments on the surface of oxides monitored by in situ DRIFTS showed that partial oxidation products, i.e., phenolate and acetate species were formed on the surface of Ca-Fe composite oxide. The further studies indicated that Ca-Fe composite oxide catalyst was easier to induce the rupture of C-Cl bond and C-C bond of aromatic rings. The best catalytic activity of Ca-Fe composite oxide may be related to the acidity, which was determined by NH 3 -TPD. The products after reaction have been analyzed by XRD and chloride selective electrode. Ca-Fe composite oxide exhibited the highest extent of mineralization for organic chlorine among the different oxides tested. The combined results of current and previous experiments demonstrated that two competitive reactions took place during the decomposition process of HCB: (1) hydrodechlorination resulting in the formation of lower chlorinated benzenes and (2) oxidation of aromatic rings leading to the rupture of aromaticity and the formation of oxidation products. The latter is the major process in the coexisted competitive reaction. A possible decomposition pathway was discussed.

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Section: Resultsmentioning

confidence: 76%

Section: Introductionmentioning

confidence: 99%

Competitive Reaction During Decomposition of Hexachlorobenzene Over Ultrafine Ca–Fe Composite Oxide Catalyst

Sun

et al. 2007

Catal Lett

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“…Lichtenberger et al [44] reported the formation of chlorophenol via the nucleophilic attack of O 2− on dichlorobenzene adsorbed onto V 2 O 5 /TiO 2 at 200-400 • C. Zhang et al [45] confirmed the presence of pentachlorophenol during the degradation of hexachlorobenzene over ultrafine ␥-Al 2 O 3 at 300 • C. In comparison, there have been few literatures reporting the existence of hydroxyl species during the degradation of PCBs over metal oxides. The XPS results provided above indicated that the reactive electrophilic oxygen species (e.g., O 2 − , O − ) were available over Fe 3 O 4 and NiFe 2 O 4 , which suggested the formation possibility of hydroxyl species during the degradation of CB-209 over the iron-based spinels.…”

Section: Hydroxyl Species Produced Over Fe 3 O 4 and Nife 2 Omentioning

confidence: 99%

“…Thus, there were the mass imbalance between the carbon contents of initial CB-209 and detected products. It was speculated that during the heating reaction of CB-209, other oxidative products should be produced on Fe 3 O 4 and favorably on NiFe 2 O 4 [44,47].…”

Section: Carbon Distribution In Productsmentioning

confidence: 99%

Degradation of polychlorinated biphenyls using mesoporous iron-based spinels

Huang¹,

Su²,

Zhang³

et al. 2013

Journal of Hazardous Materials

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h i g h l i g h t s• The NiFe 2 O 4 had the highest activity in degradation of CB-209, followed by Fe 3 O 4 .• Hydroxyl species, organic acids, PCBs and chlorobenzenes were identified as products.• Three degradation reactions and one combination reaction competitively occurred.• Hydrodechlorination of CB-209 was more favored over Fe 3 O 4 than NiFe 2 O 4 .• Oxidation reaction of CB-209 was more favored over t r a c tA series of mesoporous iron-based spinel materials were synthesized to degrade polychlorinated biphenyls (PCBs), with CB-209 being used as a model compound. The materials were characterized by X-ray powder diffraction (XRD), pore structure analysis, and X-ray photoelectron spectroscopy (XPS). A comparison of the dechlorination efficiencies (DEs) of the materials revealed that NiFe 2 O 4 had the highest DE, followed by Fe 3 O 4 . Newly produced polychlorinated biphenyls, chlorinated benzenes, hydroxyl species and organic acids were detected by gas chromatography-mass spectrometry, high performance liquid chromatography-mass spectrometry and ion chromatograph. Identification of the intermediate products indicates that three degradation pathways, hydrodechlorination, the breakage of C C bridge bond and oxidative reaction, accompanied by one combination reaction, are competitively occurring over the iron-based spinels. The relative amounts of produced three NoCB isomers were illustrated by the C Cl BDEs of CB-209 at meta-, para-and ortho-positions, and their energy gap between HOMO and LUMO. The consumption of the reactive oxygen species caused by the transformation of Fe 3 O 4 into Fe 2 O 3 in the Fe 3 O 4 reaction system, and the existence of the highly reactive O 2 −• species in the NiFe 2 O 4 reaction system, could provide a reason why the oxidation reaction was more favored over NiFe 2 O 4 than Fe 3 O 4 .

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“…In related work, some methods have been reported with metal oxide as dechlorination reagent. Among them, some oxides were used for catalytic oxidation without metal loading [19][20][21][22][23], others were acted as supports for metal elements [24,25]. In seeking to find less expensive reagents for organochlorine destruction, the behavior of CaO, MgO and Fe 2 O 3 has been examined [26][27][28] [29][30][31].…”

Section: Introductionmentioning

confidence: 99%