T:Toxic;
106-51-4Relevant articles and documents
Effect of calcination temperature on the structure and catalytic performance of copper-ceria mixed oxide catalysts in phenol hydroxylation
Amadine, Othmane,Essamlali, Younes,Fihri, Aziz,Larzek, Mohamed,Zahouily, Mohamed
, p. 12586 - 12597 (2017)
We report on highly active CuO@CeO2 catalysts prepared by the surfactant-template method and calcined at different temperatures. Then the obtained catalysts were characterized by means of various analytical techniques. Our findings show that the BET surface area and pore volume of the CuO@CeO2 catalyst measured by N2 adsorption-desorption are decreasing with the elevation of calcination temperature. From the results of XRD and XPS, we determined the oxidation state of copper in the copper-ceria mixed oxide catalysts. The CuO@CeO2 catalysts displayed good catalytic activity for the phenol hydroxylation using H2O2 as an oxidant. Moreover, we found that the catalytic activity is improved for high calcining temperature and the optimum conditions were obtained when the catalyst CuO@CeO2 is calcined at 800 °C, which lead to higher phenol conversion of 54.62% with 92.87% of selectivity for catechol and hydroquinone. More importantly, the catalyst seems to be easily recovered by simple centrifugation. The results of catalyst recycling illustrated that the catalytic activity remained high even after five cycles with slight Cu leaching and slight loss of activity. Finally, a possible mechanism in phenol hydroxylation by H2O2 over CuO@CeO2 catalyst was also proposed.
Oxidation of Electron-Rich Arenes Using HFIP-UHP System
Llopis, Natalia,Baeza, Alejandro
, p. 6159 - 6164 (2020)
The straightforward oxidation of electron-rich arenes, namely, phenols, naphthols, and anisole derivatives, under mild reaction conditions, is described by means of the use of an environmentally benign HFIP-UHP system. The corresponding quinones or hydroxylated arenes were obtained in moderate to good yields.
Nitrogen Dioxide and Related Free Radicals: Electron-transfer Reactions with Organic Compounds in Solutions containing Nitrite or Nitrate
Forni, Luigi G.,Mora-Arellano, Victor O.,Packer, John E.,Willson, Robin L.
, p. 1 - 6 (1986)
The absolute rate constants for the reaction of NO32-. (formed by one-electron reduction of nitrate) with oxygen, benzoquinone, and methyl viologen have been determined by pulse radiolysis.Experiments have shown that such reactions can occur in competition with the hydrolysis reaction leading to NO2. and that the formation of the latter can be catalysed by the presence of hydrogen or ammonium ions.Absolute rate constants for the oxidation of the phenothiazine derivative metiazinic acid, of 2,2'-azinobis-(3-ethyl-2,3-dihydrobenzothiazole-6-sulphonate), of ascorbate, and of dihydroxyfumarate by NO2. have also been measured.
Improving removal of 4-chlorophenol using a TiO2 photocatalytic system with microwave and ultraviolet radiation
Ki, Seo Jin,Jeon, Ki-Joon,Park, Young-Kwon,Jeong, Sangmin,Lee, Heon,Jung, Sang-Chul
, p. 15 - 22 (2017)
A conventional photocatalytic system is a viable tool to purify wastewaters, whereas poor degradation performance due to diverse pollutants under various conditions still leaves it behind commercial markets. This study aimed to determine the degradation e
Synthesis of Cu2 (OH)PO4 crystals with various morphologies and their catalytic activity in hydroxylation of phenol
Fu, Weiwei,Wang, Runwei,Wu, Lele,Wang, Hongbin,Wang, Xu,Wang, Aijing,Zhang, Zongtao,Qiu, Shilun
, p. 772 - 774 (2013)
Copper hydroxyphosphate (Cu2(OH)PO4) crystals with various morphologies have been successfully synthesized by a simple hydrothermal method, using different organic amines as the morphology-controlling agents. These Cu2(OH)PO4 crystals were used as catalysts for phenol hydroxylation by H2O2, and they showed distinct activities. The sheet morphology of Cu2(OH)PO4 crystals with a large percentage of reactive facets ({011} facets) exhibited enhanced catalytic activity in hydroxylation of phenol.
Preparation and photocatalytic performance of silver-modified and nitrogen-doped TiO2nanomaterials with oxygen vacancies
Zhang, Hong,Jiang, Yingyu,Zhou, Baiqin,Wei, Zhuo,Zhu, Zhenya,Han, Lijuan,Zhang, Ping,Hu, Yingying
, p. 4694 - 4704 (2021)
The photocatalysis of titanium dioxide (TiO2) exerts excellent degradation performance against contaminants in the environment. However, it prefers to absorb ultraviolet light rather than visible light, which significantly constrains its widespread use under visible light. Here, we prepared oxygen vacancy-containing TiO2viaAg-modification and N-doping. The utilization of visible light for phenol degradation was significantly enhanced by Ag/N co-doping. The characterization results showed a shuttle-like material coupled with multiple oxygen vacancies, and a well-designed experiment demonstrated that the Ti?:?N?:?Ag ratio of 1?:?0.45?:?0.32 presented optimal performance for phenol degradation. The batch experiment results also proved the modified TiO2as a potent photocatalyst against phenol degradation with an 80.8% degradation efficiency within 5 hours under visible light and with a 99.3% degradation efficiency within 2 hours under ultraviolet light. What is more, we also demonstrated that hydroxyl radical was the mainly effective radical in the mineralization of phenol and put forward a possible degradation pathway based on the observed intermediates. Lastly, the cycling tests indicated that the proposed photocatalyst is durable with a fair phenol degradation ability after recycling 5 times.
The photochemistry of 4-chlorophenol in water revisited: The effect of cyclodextrins on cation and carbene reactions
Manet, Ilse,Monti, Sandra,Bortolus, Pietro,Fagnoni, Maurizio,Albini, Angelo
, p. 4274 - 4282 (2005)
The photochemistry of 4-chlorophenol (1) in water and in the presence of cyclodextrins has been studied by means of steady-state and time-resolved experiments. These have shown that 1 undergoes photoheterolysis of the C-Cl bond in the triplet state to yield the 4-hydroxyphenyl cation 32 in equilibrium with 4-oxocyclohexa-2,5-dienylidene, 33. These triplet intermediates scarcely react with a n nucleophile, such as water, nor abstract hydrogen from this solvent, thus they are long-lived (≈1 μs). Specific trapping of both intermediates has been achieved. The cation adds to 2-propenol, kadd～1.3× 108 M-1 s-1, to form the long-lived phenonium ion 11 (with λmax = 290 nm), which then converts to 3-(4-hydroxyphenyl)propane-1,2-diol (10). Carbene 33 is trapped by oxygen to give benzoquinone and is reduced by D-glucose (kq = 8.5 × 10-1 s-1) to give the phenoxyl radical (8) and phenol (9). Cyclodextrins have been found to trap the intermediates much more efficiently (kq = 9.4×10 8M-1s-1 with β-CD), which indicates that inclusion is involved. Ground state 1 forms inclusion complexes with 1:1 stoichiometry and association constants of 140 and 300 M-1 with α- and β-CD, respectively. Complexation does not change the efficiency or the mode of photofragmentation of 1; however, it does influence the course of the reaction because the major portion of the intermediates are reduced to phenol within the cavity (k′red ≥ 5 × 107 s-1) either via a radical 8 or via a radical cation 9+. Under these conditions, neither 2-propenol nor oxygen trap the intermediates to a significant extent.
Effective photodegradation of organic pollutantsin the presence of mono and bi-metallic complexes under visible-light irradiation
Chetti, Prabhakar,Gade, Ramesh,Guguloth, Venkanna,Pola, Someshwar,Ravulapelly, Koteshwar Rao,Subburu, Mahesh
, (2021)
The synthesis of new mono and bi-metallic complexes such as Zn (II) and Ag-Zn (II) complexes with organic functional group-based ligand (OFL) presented in the current work along with the exploration of their applicability in the photocatalytic degradation
Peroxomonophosphoric Acid Oxidation. 7. Studies of the Kinetics and Substituent Effect in the Oxidation of Aniline
Panda, Abhina K.,Mahapatro, Surendra N.,Panigrahi, Ganesh P.
, p. 4000 - 4004 (1981)
The kinetics of the oxidation of aniline and 12 substituted anilines by peroxomonophosphoric acid (PMPA) have been measured.The reactions are first order in PMPA and first order in amine.The rate laws are given in eq 10 and 13.The unprotonated amine is the reactive species.Correlation of log rates with ?, ?+, ?-, and ΔpKa yielded values of ρ (-1.37), ρ+ (-1.31); ρ- (-1.38), and β (0.58), respectively.The values suggest an electron-deficient reaction center, and the Bronsted coefficient, β, indicates considerable bond formation in the transition state.All the ortho substituents provide steric retardation for the formation of the transition state.Oxidation of aniline gives azobenzene, azoxybenzene, p-aminophenol, and p-benzoquinone routed through the reactive intermediate phenylhydroxylamine.The individual reactivities of various ionized PMPA species with the amine have been estimated.
Two-Dimensional Layered Zinc Silicate Nanosheets with Excellent Photocatalytic Performance for Organic Pollutant Degradation and CO2 Conversion
Wang, Lan,Bahnemann, Detlef W.,Bian, Liang,Dong, Guohui,Zhao, Jie,Wang, Chuanyi
, p. 8103 - 8108 (2019)
Two-dimensional (2D) photocatalysts are highly attractive for their great potential in environmental remediation and energy conversion. Herein, we report a novel layered zinc silicate (LZS) photocatalyst synthesized by a liquid-phase epitaxial growth route using silica derived from vermiculite, a layered silicate clay mineral, as both the lattice-matched substrate and Si source. The epitaxial growth of LZS is limited in the 2D directions, thus generating the vermiculite-type crystal structure and ultrathin nanosheet morphology with thicknesses of 8–15 nm and a lateral size of about 200 nm. Experimental observations and DFT calculations indicated that LZS has a superior band alignment for the degradation of organic pollutants and reduction of CO2 to CO. The material exhibited efficient photocatalytic performance for 4-chlorophenol (4-CP) degradation and CO2 conversion into CO and is the first example of a claylike 2D photocatalyst with strong photooxidation and photoreduction capabilities.
