Catalytic oxidation of 1,2-dichlorobenzene over Ca-doped FeOx hollow microspheres

Ma, Xiaodong; Feng, Xin; Guo, Jie; Cao, Huiqin; Suo, Xueyue; Sun, Hongwen; Zheng, Meihua

doi:10.1016/j.apcatb.2013.10.003

Cited by 86 publications

(45 citation statements)

References 59 publications

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“…The above analysis showed that the order of the activities of the prepared materials in PCB-209 degradation was 1%Ca- was an important factor to its activity. It also confirmed that the material activity was affected by both the phase composition and the surface area caused by "Ca-doping effect" (Ma et al, 2014).…”

Section: Characterizations Of Ca Species-doped Fe 2 Osupporting

confidence: 63%

Thermal dechlorination of PCB-209 over Ca species-doped Fe2O3

Huang

Shi

et al. 2016

Chemosphere

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h i g h l i g h t s• 1% mol Ca species enhanced the activity of Fe 2 O 3 in the degradation of DecaCB.• Dominant Nona-MonoCB isomers were determined during hydrodechlorination reaction.• Thermodynamic and/or steric effects drive conversion.• Steric effect prevented the hydrodechlorination at ortho-positions. a r t i c l e i n f o b s t r a c tDegradation reaction of decachlorobiphenyl (PCB-209) was investigated over the synthesized Ca speciesdoped Fe 2 O 3 at 300°C. The 1%Ca-Fe 2 O 3 exhibited the highest activity among the four catalysts prepared with the pseudo-first order reaction at k obs = 0.103 min −1 . PCB-207, PCB-197, PCB-176, PCB-184, PCB-150, PCB-136, PCB-148, PCB-104, PCB-96, PCB-54, PCB-19, PCB-4 and PCB-1 were identified as the dominant isomers in their respective nonachlorobiphenyl (NonaCB) to monochlorobiphenyl (MonoCB) homologue groups. Analysis of the hydrodechlorination products indicated that dechlorination was much more favored on meta-and para-than on ortho-positions. The formation of significantly predominant NonaCB and octachlorobiphenyl (OctaCB) isomers was attributed to lower energy principles and to the 90°dihe-dral angles of two aromatic rings which prevented the hydrodechlorination at ortho-positions. When the number of chlorine atoms is not more than 7, the steric effect supports the formation of predominant PCB isomers having chlorines at four ortho-positions. During the dechlorination of tetrachlorobiphenyl (TetraCB) formed to generate monochlorobiphenyl (MonoCB) isomers, the chlorine atoms fully substituted at the ortho-positions have to be successively removed, with the first two dechlorinations preferentially occurring at the two different benzene rings. This is dissimilar to that of octachloronaphthalene in which the hydrodechlorination reaction happened preferentially at ortho-position due to the existence of steric effects. The opposite roles of the steric effect in ortho-position between PCB-209 and PCN-75 might be due to the difference of the π -conjugated plane caused by the dihedral angle of 90°and 0°of the two aromatic rings.

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Section: Characterizations Of Ca Species-doped Fe 2 Osupporting

confidence: 63%

Thermal dechlorination of PCB-209 over Ca species-doped Fe2O3

Huang

Shi

et al. 2016

Chemosphere

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“…35 The contribution of surface active oxygen species to the oxidation reaction has also been reported during the catalytic degradation of 1,2-dichlorobenzene over Ca-doped FeO x hollow microspheres. 38 The molecular electrostatic potential (MESP) of CN-75, as shown in Figure 4b, was calculated by DFT at the B3LYP, 6-311++G (d,p) theory level and used to characterize the chemical reactivity. The red area corresponds to a "negative MESP", whereby the energy level of the outer electron is higher and the nucleus is weakly attracted to the outer electron.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

Thermal Degradation of Octachloronaphthalene over As-Prepared Fe₃O₄ Micro/Nanomaterial and Its Hypothesized Mechanism

Lü

Zhang

et al. 2014

Environ. Sci. Technol.

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Decomposition of octachloronaphthalene (CN-75) featuring fully substituted chlorines was investigated over asprepared Fe 3 O 4 micro/nanomaterial at 300°C. It conforms to pseudo-first-order kinetics with k obs = 0.10 min −1 as comparable to that of hexachlorobenzene and decachlorobiphenyl. Analysis of the products indicates that the degradation of CN-75 proceeds via two competitive hydrodechlorination and oxidation pathways. The onset of hydrodechlorination producing lower chlorinated naphthalenes (CNs) is more favored on α-position than β-position. Higher amounts of CN-73, CN-66/67, CN-52/60, and CN-8/11 isomers were found, while small content difference was detected within the tetrachloronaphthalene and trichloronaphthalene homologues, which might be attributed to lower energy principle and steric effects. The important hydrodechlorination steps, leading to CN-73 ≫ CN-74 in two heptachloronaphthalene isomers contrary to that in technical PCN-mixtures, were specified by calculating the charge of natural bond orbitals in CN-75 and the energy of two heptachloronaphthalene radicals. On the basis of the molecular electrostatic potential of CN-75, the nucleophilic O 2− , and eletrophilic O 2 − and O − , present on the Fe 3 O 4 surface, might attack the carbon atom and π electron cloud of naphthalene ring, producing naphthol species with Mars−van Krevelen mechanism, and formic and acetic acids.

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“…We speculated that the presence of active oxygen species on the surfaces of the catalysts prepared in the current study could contribute to the reactions occurring during the degradation of CN-27. [37][38][39] In this study, the proportions of electrophilic oxygen (O a ) observed on the FeAl-1, FeAl-5 and FeAl-10 composites were calculated as 20.4%, 33.9% and 28.1%, respectively. The higher ratios of electrophilic oxygen (O 2 and O -) observed in the FeAl-5 and FeAl-10 materials could therefore explain why these materials showed higher reactivity toward the degradation of CN-27 than FeAl-1.…”

Section: Activity Analysismentioning

confidence: 99%

Degradation of one-side fully-chlorinated 1,2,3,4-tetrachloronaphthalene over Fe–Al composite oxides and its hypothesized reaction mechanism

et al. 2017

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Catalytic oxidation of 1,2-dichlorobenzene over Ca-doped FeOx hollow microspheres

Cited by 86 publications

References 59 publications

Thermal dechlorination of PCB-209 over Ca species-doped Fe2O3

Thermal dechlorination of PCB-209 over Ca species-doped Fe2O3

Thermal Degradation of Octachloronaphthalene over As-Prepared Fe₃O₄ Micro/Nanomaterial and Its Hypothesized Mechanism

Degradation of one-side fully-chlorinated 1,2,3,4-tetrachloronaphthalene over Fe–Al composite oxides and its hypothesized reaction mechanism

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Catalytic oxidation of 1,2-dichlorobenzene over Ca-doped FeOx hollow microspheres

Cited by 86 publications

References 59 publications

Thermal dechlorination of PCB-209 over Ca species-doped Fe2O3

Thermal dechlorination of PCB-209 over Ca species-doped Fe2O3

Thermal Degradation of Octachloronaphthalene over As-Prepared Fe3O4 Micro/Nanomaterial and Its Hypothesized Mechanism

Degradation of one-side fully-chlorinated 1,2,3,4-tetrachloronaphthalene over Fe–Al composite oxides and its hypothesized reaction mechanism

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Thermal Degradation of Octachloronaphthalene over As-Prepared Fe₃O₄ Micro/Nanomaterial and Its Hypothesized Mechanism