Search results for "Partial oxidation"

Heterogeneous Photocatalysis and Photoelectrocatalysis: From Unselective Abatement of Noxious Species to Selective Production of High-Value Chemicals

2015

Heterogeneous photocatalysis and photoelectrocatalysis have been considered as oxidation technologies to abate unselectively noxious species. This article focuses instead on the utilization of these methods for selective syntheses of organic molecules. Some promising reactions have been reported in the presence of various TiO2 samples and the important role played by the amorphous phase has been discussed. The low solubility of most of the organic compounds in water limits the utilization of photocatalysis. Dimethyl carbonate has been proposed as an alternative green organic solvent. The recovery of the products by coupling photocatalysis with pervaporation membrane technology seems to be a…

Surfactant based synthesis of oxidic catalysts and catalyst supports

1995

The preparation of mesostructured metal oxides based on the surfactant controlledsynthesis of MCM-41 is presented. It can be expected that the new metal oxide materials will exhibit a high surface area of nearly 1000 m 2 /g and could have a possible use as catalysts, especially in partial oxidation reactions and as hosts for quantum sized material, if the surfactant can be removed without destroying the structure.

Photocatalytic activity of binary and ternary SnO2–ZnO–ZnWO4 nanocomposites

2015

Binary and ternary SnO2-ZnO-ZnWO4 nanocomposites were prepared by a sol-gel route. The photocatalytic activity of the samples was evaluated through the decomposition of 4-nitrophenol and partial oxidation of 4-methoxybenzyl alcohol to p-anisaldehyde. All the mixed catalysts revealed higher photoactivity than bare ZnO, SnO2 or ZnWO4 and the best performances were exhibited by the binary nanocomposites. The high photocatalytic activity was explained by the presence of heterojunctions among different semiconductors that enhance the separation of the photogenerated electron-hole pairs, hindering their recombination. As a general consideration, an essential role was played by the electronic feat…

Nanosponge-C3N4 composites with improved photocatalytic activity for selective partial alcohol oxidation in aqueous suspension

2022

Composites of C3N4 with nanosponges based on β-cyclodextrins containing a 5% w/w of C3N4 were synthesised, physicochemicaly characterised and tested as heterogeneous photocatalysts for the degradation of 4-nitrophenol and for the partial oxidation of 5-hydroxymethyl-2-furfural and veratryl alcohol. The results outline a synergistic effect in terms of conversion and selectivity. The association of the nanosponges with the C3N4 enhances the photocatalytic activity of the semiconductor, possibly due to the local concentration effect occurring on the photocatalyst surface that would involve a concentration into the nanosponge matrix ca. 500 times larger than in the solution bulk. Composites of …

Photoelectrochemical and EPR features of polymeric C 3 N 4 and O-modified C 3 N 4 employed for selective photocatalytic oxidation of alcohols to alde…

2019

Four different C 3 N 4 specimens have been prepared, a bulk one (MCN), a thermally etched (MCN-TE), a solid prepared by hydrothermally treating MCN with H 2 O 2 (MCN-H 2 O 2 ) and a polymeric carbon nitride-hydrogen peroxide adduct (MCN-TE-H 2 O 2 ). The principal aim of this work was to correlate the capability of the prepared material to generate reactive oxygen species (ROS), under irradiation, with their photocatalytic activities in terms of conversion and selectivity for partial oxidation reactions. Photoelectrochemical studies revealed that MCN-TE represented the best material in terms of photoconductivity, whereas MCN-H 2 O 2 was defective and evidenced a poor mobility of carriers. E…

Stabilisation of LDPE cross-linked in the presence of peroxidesII. FTIR study of chemical changes taking place in the LDPE–dicumyl peroxide–Irganox 1…

2000

Abstract The chemical changes taking place in the systems: LDPE–Irganox 1081, LDPE–dicumyl peroxide and LDPE–Irganox 1081–dicumyl peroxide, after homogenisation (in a rolling mill at 130°C) and after homogenisation and cross-linking (at 180°C and 5.0 MPa for 20 min) were investigated by FTIR. It was found that the OH groups in Irganox 1081 were in a bound form, and were most probably linked to the sulphur co-ordination centre. Further, the presence of dicumyl peroxide without Irganox 1081 in LDPE resulted in the formation of hydroperoxide groups at a temperature of 130°C, which were replaced by free hydroxy and carbonyl groups of a ketonic type after cross-linking. Simultaneous addition of …

Glycerol Partial Oxidation in Aqueous Solution by Home Prepared TiO2 Photocatalyst

2010

6th European Meeting on Solar Chemistry and Photocatalysis: Environmental Applications (SPEA6) -- JUN 13-16, 2010 -- Prague, CZECH REPUBLIC

Photocatalytic partial oxidation of phenenthrene in green organic solvents

2014

Synthesis and support composition effects on CH4 partial oxidation over Ni–CeLa oxides

2015

Abstract Two series of Ni (6 wt%) catalysts supported over CeO 2 , La 2 O 3 and mixed CeO 2 –La 2 O 3 were prepared by co-precipitation and by wet-impregnation. The effect of the two Ni loading procedures on the catalyst structural properties was investigated by XRD, TPR and XPS. The catalytic behavior of the catalysts was tested in the methane partial oxidation reaction performed at 1 atm in a temperature range of 400–800 °C using dilute feed gas mixture with CH 4 /O 2  = 2 and gas hourly space velocity of 60,000 ml g −1  h −1 . Total methane combustion was observed within the 450 °C ≤  T ≤ 650 °C temperature range. Above 650 °C partial oxidation of methane started to occur, reaching at 80…

SrTiO 3 -based perovskites: Preparation, characterization and photocatalytic activity in gas–solid regime under simulated solar irradiation

2015

Strontium titanate-based perovskites have been prepared in the presence of Y and Co with the aim to substitute Sr and Ti, respectively, in the ST crystalline structure. The obtained samples have been characterized by XRD, Raman spectroscopy, FE-SEM, XPS and tested as photocatalysts in two gas-solid regime reactions: (i) 2-propanol complete mineralization and (ii) propene partial oxidation, using a system simulating solar irradiation. All the tested samples resulted active as photocatalysts but with significant differences. The lattice substitution of Sr by Y displays a beneficial effect on the 2-propanol photodegradation. Conversely, the partial presence of cobalt on the ST surface, as Co-o…