Search results for "LYST"
showing 10 items of 904 documents
Ferric sludge derived from the process of water purification as an efficient catalyst and/or support for the removal of volatile organic compounds
2019
Ferric chloride solutions are used as coagulants or flocculants in water treatment operations for human consumption. This treatment produces large amounts of clay-type solids formed mainly of montmorillonite with iron oxides and humic substances. This ferric sludge can be used as an efficient catalyst for the removal of volatile organic compounds (VOCs) by total oxidation. This waste isolated in the purification process has been activated by calcinations in air, characterized by several physicochemical techniques and employed as a catalyst for the removal by total oxidation of representative VOCs: toluene, propane and mixtures of toluene/propane with or without water. This ferric sludge has…
Electrochemical treatment of aqueous solutions of organic pollutants by electro-Fenton with natural heterogeneous catalysts under pressure using Ti/I…
2018
The treatment of toxic organic pollutants by electro-Fenton (EF) presents some drawbacks such as the necessity to work at low pH and the low solubility of oxygen in water contacted with air or oxygen at room pressure that results often in slow and relatively low abatements. Here, the coupled adoption of natural heterogeneous catalysts and of relatively high pressure was proposed in order to improve the performances of EF for the treatment of organic pollutants. Caffeic acid (CA) and 3-chlorophenol were used as model resistant organic pollutants. EF process was performed using both conventional homogeneous FeSO4 and natural heterogeneous catalysts (pyrite, chalcopyrite, Fe2O3 and Fe3O4) as i…
A survey of photocatalytic materials for environmental remediation
2012
Abstract Heterogeneous photocatalysis is an advanced oxidation process which has been the subject of a huge amount of studies related to air cleaning and water purification. All these processes have been carried out mainly by using TiO 2 -based materials as the photocatalysts and ca. 75% of the articles published in the last 3 years is related to them. This review illustrates the efforts in the search of alternative photocatalysts that are not based on TiO 2 , with some exceptions concerning particularly innovative modifications as nanoassembled TiO 2 or TiO 2 composites with active carbon, graphite and fullerene. Papers reporting preparation, characterization and testing of binary, ternary…
Opals infiltrated with a stimuli-responsive hydrogel for ethanol vapor sensing
2013
We report on a novel class of optical materials for ethanol vapor sensing, based on polystyrene opals infiltrated with an innovative stimuli responsive hydrogel. We describe the fabrication process of the bare polystyrene opals and their subsequent infiltration. The optical characterization of the photonic crystal templates was performed to prove the good quality of the samples. Measurements on the infiltrated opals showed that the transmission spectra in the visible range strongly change at varying concentrations of ethanol vapor. The fabricated structures show a linear optical response in the visible range, for high values of ethanol concentration.
Polystyrene nanoparticles in the presence of (ethylene oxide)13(propylene oxide)30(ethylene oxide)13, N,N-dimethyloctylamine-N-oxide and their mixtur…
2008
Polystyrene nanoparticles were synthesized by emulsion polymerization of styrene. They were functionalized using the conventional surfactant N,N-dimethyloctylamine-N-oxide (ODAO), the tri-block copolymer (ethylene oxide)13(propylene oxide)30(ethylene oxide)13 (L64) and their mixtures. To this purpose, dynamic light scattering and calorimetric experiments were carried out and provided information consistent to each other. The L64 adsorption is Langmuir-type in the copolymer dilute regime and generates complex structures at larger concentrations. In the region where ODAO is in the unimeric state, the adsorption process is cooperative leading to hemi-micelle formation at the polystyrene nanopa…
Introducing an amine functionality at the block junction of amphiphilic block copolymers by anionic polymerization strategies
2011
A series of block copolymers bearing a single amino in-chain functionality was synthesized via anionic polymerization of styrene and ethylene oxide. By means of both a conventional and a continuous setup, living polystyrene was quantitatively end functionalized with an oxirane (DBAG) prior to the polymerization of the poly(ethylene oxide) segment. The in-chain amine was conjugated with a fluorescent dye.
Sol–gel material as a support of organometallic catalyst for ethylene polymerization
2008
Abstract The sol–gel procedure was applied to obtain powdery materials with different structures and morphology. It was possible to produce almost non-porous silica powder, with an extremely low surface area (ca. 4 m 2 /g) and very high uniformity of spherical particles as well as materials with various uniformity of particles and different porosity, most likely associated with increasing pore volume. Dependent on the properties of the carrier, the resulting supported vanadium catalysts (VOCl 3 /AlEt 2 Cl) showed significant differences concerning activity and stability. It was confirmed that improved hydrophobicity of the carrier’s surface may be useful and improve the activity of the syst…
Effect of silica-type sol–gel carrier’s structure and morphology on a supported Ziegler–Natta catalyst for ethylene polymerization
2006
Abstract Silica xerogels with different structures and morphology, synthesized using a sol–gel procedure, were used as a carrier of vanadium catalysts (VOCl 3 /AlEt 2 Cl) for ethylene polymerization. Two techniques of catalyst synthesis were applied: slurry impregnation and gas-phase adsorption and the relevant polymerization methods were then employed. The effect of the carrier structure and morphology on the vanadium loading in the catalysts, the catalyst’s activity and kinetic stability were investigated.
The nickel-support interaction as determining factor of the selectivity to ethylene in the oxidative dehydrogenation of ethane over nickel oxide/alum…
2021
[EN] Nickel oxides supported on gamma-alumina (Ni-loading from 5 to 30 wt% NiO) have been synthesized and tested in the oxidative dehydrogenation (ODH) of ethane in order to determine the importance of the NiO-support interaction. The best performance was achieved by the catalyst with 15 wt% NiO; higher NiO-loadings lead to the formation of unselective bulk-like NiO and lower Ni-loadings present high proportion of free alumina surface sites. The presence of oxalic acid and/or niobium in the synthesis gel resulted in the formation of NiO particles with similar size, but higher crystallinity and reducibility than the standard 15 wt% NiO catalyst. The obtained results have revealed that, in ad…
Nickel oxide supported on porous clay heterostructures as selective catalysts for the oxidative dehydrogenation of ethane
2016
[EN] Porous clay heterostructures (PCH) have shown to be highly efficient supports for nickel oxide in the oxidative dehydrogenation of ethane. Thus NiO supported on silica with a PCH structure shows productivity towards ethylene three times higher than if NiO is supported on a conventional silica. This enhanced productivity is due to the increase in the catalytic activity and especially to the drastic increase in the selectivity to ethylene. Additionally, PCH silica partially modified with titanium in the columns (PCH-Ti) have also been synthesized and used as supports for NiO. An enhanced activity and selectivity to ethylene was found over NiO supported over PCH-Ti compared to the corresp…