213 results on '"TOTAL OXIDATION"'
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2. Chemical and Fatty Acid Characterization of the Penja Fish (Sicyopterus parvei) Oil in Budong-Budong River Estuary, West Sulawesi, Indonesia.
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Astuti, Ida, Nurdiani, Rahmi, Sulistiyati, Titik Dwi, and Fadjar, Mohamad
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FATTY acids , *FREE fatty acids , *FISH oils , *GAS chromatography/Mass spectrometry (GC-MS) , *CHEMICAL yield , *ENDEMIC fishes - Abstract
The Penja, Sicyopterus parvei, is an endemic fish species in the Budong-Budong River, Central Mamuju, West Java, Indonesia. This species has a high nutritional content for human health. However, there is no research regarding the characterization of penja fish. This study aimed to determine the chemical quality and characteristics of the penja fish oil (Sicyopterus parvei) from the Budong-Budong River Estuary. Penja fish samples were extracted with 96% ethanol, purified and bleached with 3% bentonite. The yield and chemical characteristics of penja fish oil, including acid number, free fatty acid number, anisidine and peroxide value were determined. The characteristics of penja fish fatty acid were assessed using GCMS (Gas Chromatography-Mass Spectrometry). All chemical characteristics of penja fish crude oil were higher than penja fish pure oil, including oil yield (8.55% vs 2.83%), acid number (50.75% vs 19.40%), free fatty acids (19.35% vs 9.56%), peroxide value (8.51 vs 2.58 meq/kg), anisidin value (4.14 vs 2.38 meq/kg) and total oxidation (20.95 vs 7.38 meq/kg). The fatty acid of penja fish recorded 10.62% PUFA, 19.03% MUFA and 35.3% SFA. Besides, penja fish contain omega 3, viz., DHA and EPA. The quality of the penja fish oil after purification was better than that before purification. Free fatty acids did not meet either the Indonesian National Standard (SNI) nor the International Fish Oil Standards (IFOS), while the peroxide value, anisidin number and total oxidation met both standards. [ABSTRACT FROM AUTHOR] more...
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- 2023
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Catalog
3. Influence of Transesterification Catalysts Synthesized with Citric Acid on the Quality and Oxidative Stability of Biodiesel from Black Soldier Fly Larvae.
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Kathumbi, Lilies K., Home, Patrick G., Raude, James M., Gathitu, Benson B., Gachanja, Anthony N., Wamalwa, Anthony, and Mibei, Geoffrey
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CITRIC acid ,TRANSESTERIFICATION ,FATTY acid methyl esters ,GAS chromatography/Mass spectrometry (GC-MS) ,BIODIESEL fuels - Abstract
In biodegradable waste management, use of Black Soldier Fly Larvae (BSFL) is a promising method for bioconversion of waste into crude insect fat as feedstock for biodiesel production. Biodiesel is a renewable alternative to fossil fuel, but it is more susceptible to oxidative degradation over long-term storage. This study investigates the effectiveness of NaOH and CaO catalysts synthesized with citric acid (CA) in improving the oxidative stability of biodiesel. The biodiesel and biodiesel/diesel blends derived from BSFL were stored at 63 °C for 8 days. The quality of biodiesel was determined by analysis of the physicochemical and fuel properties by: Fourier transform infrared (FTIR) spectroscopy, ultraviolet visible spectrophotometer (UV-Vis), gas chromatography-mass spectroscopy (GC-MS), bomb calorimeter and titration methods. Properties that were analyzed included: peroxide value, acid value, iodine value, refractive index, density, calorific value, total oxidation (TOTOX), anisidine value and fatty acid profile. The results showed that catalysts synthesized with CA retarded the decomposition of unsaturated fatty acids, resulting in a significant delay in the formation of hydroperoxides. Besides, 10-oxo-octadecanoic acid, an antioxidant, was present in biodiesel produced using catalysts synthesized with CA, hence enhancing the stability of biodiesel against oxidation. Catalysts synthesized with CA slowed the decomposition of monounsaturated fatty acids by 6.11–11.25%. Overall, biodiesel produced using catalysts synthesized with CA was observed to degrade at a slower rate than biodiesel produced using commercial calcium oxide. The reduced degradation rates demonstrate the effectiveness of the synthesized catalysts in enhancing the oxidation stability and consequently the fuel qualities of biodiesel from BSFL under accelerated storage. [ABSTRACT FROM AUTHOR] more...
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- 2022
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4. Supported RuxIr1‐xO2 Mixed Oxides Catalysts for Propane Combustion: Resistance Against Water Poisoning.
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Wang, Zheng, Wang, Wei, Khalid, Omeir, Weber, Tim, Spriewald Luciano, Alexander, Zhan, Wangcheng, Smarsly, Bernd M., and Over, Herbert
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RUTHENIUM catalysts , *MIXED oxide catalysts , *POISONING , *CATALYST poisoning , *PROPANE , *COMBUSTION - Abstract
Mixed oxide catalysts RuxIr1‐xO2 with varying composition x (x=0, 0.25, 0.5, 0.75, 1.0) supported on CeO2, γ‐Al2O3 or ZrO2 are successfully prepared and tested in the catalytic propane combustion in terms of activity and stability. Pure IrO2 reveals a significantly lower activity than RuxIr1‐xO2 with x≥0.25. For low conversion, pure RuO2 on CeO2 turns out to be the most active catalyst, while at higher conversion, Ru0.75Ir0.25O2 on ZrO2 is found to be more active than RuO2, pointing towards synergism of Ru and Ir sites. Long‐term stability and also the resistance against water poisoning are highest for ZrO2‐supported catalysts. The higher the Ir concentration in the active component RuxIr1‐xO2 the more susceptible is the catalyst to water poisoning. Water poisoning is shown to be reversible, consistent with a blocking of catalytically active sites by water adsorption. [ABSTRACT FROM AUTHOR] more...
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- 2022
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5. Effectiveness of toluene mineralization by gas-phase oxidation over Co(II)/SiO2 catalyst with ozone.
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Machniewski, Piotr, Biń, Andrzej, and Kłosek, Katarzyna
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TOLUENE ,CARBON dioxide in water ,OZONE ,CATALYST poisoning ,MINERALIZATION ,OXIDATION ,CATALYSTS - Abstract
The results of experimental study on effectiveness of gas-phase total oxidation of toluene towards carbon dioxide and water with the aid of ozone over Co(II)/SiO
2 catalyst are presented in this work. The main objective of the work was to determine ozone demand necessary for total mineralization of toluene at the temperature range of 40–100°C chosen to minimize catalyst poisoning by water. Complete mineralization of toluene was possible if sufficient ozone/toluene ratio was maintained in the gas supplied to the reactor. For ozone/toluene molar ratios less than 20 the extent of toluene mineralization increased with temperature up to a plateau starting at approximately 60°C, which was caused by ozone shortage. Stoichiometry of the total oxidation of toluene with ozone indicates that only one oxygen atom in the ozone molecule is used for the oxidation of toluene, to achieve complete mineralization. Experimentally determined ozone/toluene ratio (20–25) necessary for the total oxidation of toluene was larger than the theoretical one mostly due to ozone losses resulting from its 'unproductive' decomposition. At the range of lower values of mineralization rate, the toluene oxidation proceeds according to a more efficient mechanism, indicating less ozone demand being between 6 and 18 moles of ozone per mole of toluene. A possible mechanism of toluene oxidation was suggested. The mechanism involves the formation of •OH radicals, which may explain the effectiveness of Co(II)/SiO2 catalyst in combination with ozone for the oxidation of toluene and other aromatic VOCs in a low-temperature process. [ABSTRACT FROM AUTHOR] more...- Published
- 2021
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6. Bulk defect-dependent initial steps of acetone oxidation on rutile TiO2(110).
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Kräuter, Jessica and Al-Shamery, Katharina
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RUTILE , *PROPENE , *ACETONE , *CARBON dioxide in water , *INFRARED absorption , *SURFACE reactions , *SURFACE temperature - Abstract
Systematic model investigations revealed that defects, particularly bulk Ti3+ interstitials, play a crucial role in directing reactions of alcohols and aldehydes at rutile Titania (TiO2), a cheap, nontoxic and earth abundant catalyst. Coadsorption with oxygen may enhance the population of certain reaction paths. As systematic studies on the reactivity of ketones are rare, we studied the interaction of acetone with slightly (∼5%) and highly (∼20%) reduced rutile TiO2(110) surfaces by Temperature Programmed Desorption (TPD) and polarised Fourier-Transform Infrared Reflexion Absorption Spectroscopy (FT-IRRAS) to elucidate surface intermediates and reaction products. For low defect densities the only reaction observed occurs at high temperatures resulting in the formation of propane and propene of less than 1%. At high Ti3+ defect densities a stabilisation of acetone on the surface by the formation of a diolate was observed. In the presence of oxygen, the partial formation of a tilted acetone species is apparent in FT-IRRAS. A concomitant activation of the CH-bond can be attributed to the interaction with Oad atoms and can relate to thermally induced low temperature decomposition to water and carbon dioxide. However, in contrast to alcohols and aldehydes, both intermediates do not react to other more valuable products. [ABSTRACT FROM AUTHOR] more...
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- 2021
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7. Combustion of toluene over cobalt-modified MFI zeolite dispersed on monolith produced using 3D printing technique.
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Rokicińska, Anna, Drozdek, Marek, Bogdan, Elżbieta, Węgrzynowicz, Adam, Michorczyk, Piotr, and Kuśtrowski, Piotr
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THREE-dimensional printing , *PRINTMAKING , *ZEOLITES , *TOLUENE , *VOLATILE organic compounds , *COMBUSTION - Abstract
[Display omitted] • Ordered ceramic monoliths are formed by casting using 3D printed resin templates. • Coating with a MFI zeolite layer increases porosity of monolith walls. • Various amounts of Co 3 O 4 are deposited by ion-exchange or impregnation technique. • Catalytic activity of Co 3 O 4 -modified monolith is higher than that of reference Co-BEA. • Co 3 O 4 -containing monoliths show very high stability and selectivity to CO 2. A facile method of fabrication of ceramic monoliths assisted by 3D printing was developed for preparation of Co 3 O 4 -based catalysts of total oxidation of volatile organic compounds. The proposed approach was based on the production of a resin template, which was subsequently used at a casting step for the construction of corundum monolith. The walls of this material were additionally coated with a MFI zeolite layer providing the possibility of modification with a Co 3 O 4 precursor using ion-exchange and impregnation techniques. The parent and Co 3 O 4 -modified monoliths with varying active phase content were characterized by SEM/EDS, XRD, XRF, XPS, UV–vis-DR and H 2 -TPR. Their catalytic performance in the toluene combustion was also tested. It was shown that the formation of Co 3 O 4 spinel particles highly dispersed on the zeolite-coated monolith resulted in excellent catalytic activity measured by very high TOF values. Furthermore, stability tests confirmed that the obtained monolith catalysts can work for prolonged reaction time without noticeable changes in the toluene conversion and selectivity to CO 2. [ABSTRACT FROM AUTHOR] more...
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- 2021
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8. Assessing the quality and the degree of rancidity of frying oils used in drive-in restaurants of tamil nadu.
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POOJA B., BISWAL. R., ABHISHEK, SARATHCHANDRA, GHADEVARU, and SELVAM. S., PERIYAR
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FATTY acids , *OXIDATION , *FAST food restaurants , *PEROXIDES , *FRIED food - Abstract
With growing popularity, fried food items are eaten worldwide because of their distinctive sensory properties, particularly the frying taste, the golden-brown color and the crisp consistency. When the oil is being heated or fried with the food stuffs for a long time there will be a change in the quality of oils. The continuous heating affects the quality parameters like free fatty acid, iodine values, acid values and peroxide value. Total of 25 frying oil samples were collected from the five districts of the fast-food restaurants. The first stage of the study was to evaluate the quality parameters such as the Free Fatty Acid content and Iodine number on analysis which some samples show highest FFA content and lower Iodine number that tends to have increase number of unsaturation fatty acids in cooked oil with low level of iodine number. The second stage of the work was to assess the oxidation and rancidity parameters such as Peroxide value, p-Anisidine value, TOTOX, acid value and viscosity. Most of the sample's results showed that the rancidity values and oxidation values were beyond the standard limits. The main objective of the work was to assess the quality of the randomly collected oil samples from the restaurants and fast-food shops in five districts. The bulk of fast-food restaurant used oil was over-degraded, containing dangerous secondary oxidative compounds, and fast-food restaurant use of non-standard frying oil has risen. [ABSTRACT FROM AUTHOR] more...
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- 2021
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9. Mechanochemical Synthesis as an Alternative Effective Technique for the Preparation of the Composite Catalysts.
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Morozova, O. S., Firsova, A. A., Tyulenin, Yu. P., Vorobieva, G. A., and Leonov, A. V.
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COPPER oxide , *TEMPERATURE-programmed reduction , *COPPER catalysts , *SCANNING electron microscopy , *METALLIC oxides , *CATALYSTS , *COPPER oxide films - Abstract
Abstarct: —Mechanochemical synthesis in a ball mill was applied for the nanocomposite Cu(CuO)–CeO2 catalyst preparation from CeO2 and following dopants: Cu metal and copper oxides of different morphology and composition (CuO pure and CuO containing 4 or 16.5 wt % of Cu2O). The materials obtained were examined with the use of X-ray phase analysis, scanning electron microscopy, temperature-programmed reduction in CO, H2, C2H6 (TPR-СО, TPR-Н2, and TPR-С2Н6), and tested as catalysts in reactions of selective CO oxidation in H2 excess (CO-PROX) and total C2H6 oxidation. New forms of oxygen with high low-temperature reactivity towards CO, H2, and C2H6 were found by TPR in the samples synthesized. It was shown that CO conversion was slightly affected by the dopant nature in the dopant-CeO2 mixture. Contrary, C2H6 conversion at low temperatures depends on dopant composition. The highest C2H6 conversion at 400°С (91.4%) was observed on Cu–CeO2. The lowest one (54.2%) was observed on CuO–CeO2. As was demonstrated, mechanochemical synthesis is a universal technique to produce copper oxide–ceria catalysts. [ABSTRACT FROM AUTHOR] more...
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- 2020
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10. The potential use of HNO3-treated clinoptilolite in the preparation of Pt/CeO2-Clinoptilolite nanostructured catalyst used in toluene abatement from waste gas stream at low temperature
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Majid Amereh, Mohammad Haghighi, and Pooya Estifaee
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Clinoptilolite ,Pt/CeO2-Clinoptilolite ,Toluene ,Total oxidation ,Air treatment ,Chemistry ,QD1-999 - Abstract
In this paper, CeO2(30%)/Clinoptilolite was synthesized via HNO3 treatment and co-precipitation methods and then 1% Pt was dispersed over support by ultrasound assisted wet impregnation. The synthesized samples were characterized using XRF, XRD, FESEM, N2 adsorption and FTIR techniques. The obtained results from XRD revealed the main phase in utilized clay is clinoptilolite and also formation of amorphous structure was proved after acid treatment. FESEM micrographs confirmed significant structural changes in clinoptilolite after acid treatment and also formation of ceria nanoparticles. N2 adsorption presented large enough surface area for Pt/CeO2-Clinoptilolite nanostructured catalyst to be used for toluene oxidation. Finally, activity results indicated that synthesized nanostructured catalyst was highly active and stable and could eliminate more than 90% of toluene at 130 °C. Utilizing inexpensive materials in synthesis and assisting ultrasound in dispersion of active phase have made Pt(1%)/CeO2(30%)-Clinoptilolite a nominee to be used for catalytic oxidation of toluene. more...
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- 2018
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11. Catalytic abatement of dichloromethane over transition metal oxide catalysts: Thermodynamic modelling and experimental studies.
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El Assal, Zouhair, Ojala, Satu, Zbair, Mohamed, Echchtouki, Hafid, Nevanperä, Tuomas, Pitkäaho, Satu, Pirault-Roy, Laurence, Bensitel, Mohammed, Brahmi, Rachid, and Keiski, Riitta L.
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TRANSITION metal catalysts , *TRANSITION metal oxides , *CHLORINE , *METAL catalysts , *INDUSTRIAL wastes , *PRECIOUS metals , *METALLIC oxides - Abstract
Dichloromethane (DCM) is a noxious chemical that is widely used in industry. The current work focuses on the catalytic abatement of DCM from industrial effluents to minimize its harmful effects to the environment and human wellbeing. Three transition metal oxide catalysts (V, Cu and Mn) supported on γ-Al 2 O 3 were synthetized for total oxidation of DCM in presence of steam. Thermodynamic modelling was used to reveal information related to the stability of the used transition metal oxides in the abatement conditions. The results showed that with 10 wt-% CuO and 10 wt-% V 2 O 5 containing catalysts 100% conversion of DCM together with 90% HCl yield and insignificant by-product formation can be achieved at temperature around 500 °C. According to modelling, V 2 O 5 should be stable at the conditions of DCM oxidation, while CuO would be more stable at higher temperature level (decomposition of CuCl 2 starts at 300 °C). MnCl 2 remains stable until 800 °C, which leads to deactivation of MnO 2 catalyst. Presence of steam inhibits the poisoning of the materials by chlorine based on thermodynamic calculation. XRF analysis supports the results of thermodynamic modelling – used MnO 2 and CuO catalysts contain chlorine, which was not detected in case of V 2 O 5 /Al 2 O 3. CuO/γ-Al 2 O 3 seems to be a good alternative to noble metal catalysts for the total oxidation of dichloromethane when used in the presence of steam and the temperatures above 300 °C to minimize Cl-poisoning. The outcomes of this study showed that the prepared metal oxides are promising catalysts to minimize pollution caused by chlorinated volatile organic compounds. [ABSTRACT FROM AUTHOR] more...
- Published
- 2019
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12. Size-activity relationship of iridium particles supported on silica for the total oxidation of volatile organic compounds (VOCs).
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Schick, Lukas, Sanchis, Rut, González-Alfaro, Vicenta, Agouram, Said, López, José Manuel, Torrente-Murciano, Laura, García, Tomás, and Solsona, Benjamín
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VOLATILE organic compounds , *IRIDIUM , *PRECIOUS metals , *IRIDIUM catalysts , *PLATINUM group , *PALLADIUM oxides - Abstract
Graphical abstract Highlights • Catalytic activity increases when the iridium oxide particle size decreases. • Iridium on silica highly active in VOC oxidation and if calcined at >350 °C highly stable. • Reducibility is a determining factor according to a MVK mechanism. Abstract This systematic catalytic study reveals for the first time a strong size-activity relationship of iridium-based catalysts for the total oxidation of short chain alkanes reaction. Silica has been selected as support for its inertness and weak silica-iridium interaction to avoid its contribution to the catalytic activity. The size of the iridium particles can be increased from ∼5 to 27 nm by increasing the calcination temperature from 350 to 750 °C. Unlike other precious metals such as palladium or platinum, in the case of iridium catalysts, the oxidation activity increases when the size decreases. This effect is also maintained when the activity is normalized per metallic surface area revealing a higher intrinsic activity as the iridium size decreases beyond its simple increase in metallic surface area. Indeed, as the particle size decreases, a higher proportion of highly reducible iridium species as well as an increase in defective Ir3+ species on the surface is observed by XPS, directly related to the enhanced activity. The highly reducible species are oxidized under the reaction conditions, leading to an initial decrease in activity before reaching a stable rate of oxidation reaction. This knowledge provides useful guidelines for the design of iridium-based systems for the total oxidation of volatile organic compounds at low temperatures. [ABSTRACT FROM AUTHOR] more...
- Published
- 2019
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13. Novel CuO-containing catalysts based on ZrO2 hollow spheres for total oxidation of toluene.
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Kondratowicz, Tomasz, Drozdek, Marek, Rokicińska, Anna, Natkański, Piotr, Michalik, Marek, and Kuśtrowski, Piotr
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OXIDATION of toluene , *COPPER oxide , *ZIRCONIUM oxide , *CATALYSTS , *CALCINATION (Heat treatment) , *X-ray diffraction , *ADSORPTION (Chemistry) - Abstract
Abstract A bottom-up strategy was used to construct SiO 2 @ZrO 2 core-shell materials with amorphous or tetragonal structure of ZrO 2 induced by calcination temperature. After etching of the SiO 2 core with NaOH, @ZrO 2 hollow spheres were formed as supports for different amounts of CuO (2.5–15.0 wt% of Cu). Significant differences in porosity and distribution of Cu2+ species were identified by X-ray diffraction, low-temperature N 2 adsorption, UV-vis-DR and X-ray photoelectron spectroscopy. The Cu-containing catalysts based on tetragonal @ZrO 2 exhibited higher surface areas and surface concentrations of finely dispersed Cu2+ compared to the series prepared using amorphous @ZrO 2. Moreover, CuO particles deposited on the tetragonal ZrO 2 shells appeared to be easier reducible during temperature-programmed reduction (TPR) measurements. Consequently, these catalysts were more active in the total oxidation of toluene, which mainly proceeded by the Mars-van Krevelen mechanism. Nevertheless, an analysis of correlation between the catalytic activity and reducibility for both studied catalyst series revealed that oxygen vacancies present on the surface of tetragonal ZrO 2 clearly promote the reaction rate. The developed materials can be considered as useful for commercial application due to high selectivity to the combustion products (CO 2 and H 2 O) and stable work even in a wide range of toluene concentrations and a moisture presence. Graphical abstract Image 1 Highlights • Tetragonal ZrO 2 is formed above 850 °C in SiO 2 @ZrO 2 core-shell composites. • High surface ZrO 2 hollow spheres remain after etching of silica core with NaOH. • Very good dispersion of Cu2+ species on tetragonal ZrO 2 shells is obtained. • Easy reducibility of CuO favors high catalytic activity in toluene combustion. • Oxygen vacancies of ZrO 2 support enhance the rate of total oxidation of toluene. [ABSTRACT FROM AUTHOR] more...
- Published
- 2019
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14. Polymer template assisted construction of spherical Co3O4@meso-SiO2 yolk-shell nanoreactors for catalytic combustion of volatile organic compounds.
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Rokicińska, Anna, Łątka, Piotr, Olszański, Bazyli, Żurowska, Magdalena, Dębosz, Marek, Michalik, Marek, and Kuśtrowski, Piotr
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COMBUSTION , *POLYMERS , *ADSORPTION capacity , *X-ray diffraction , *VOLATILE organic compounds - Abstract
[Display omitted] • Spherical polymer particles are scaffolds in formation of mesoporous SiO 2 shells. • Adsorption properties of template favor aggregation of Co2+ ions within SiO 2 shells. • Choice of template affects strength of interaction of Co 3 O 4 nanograins with SiO 2. • Space inside porous shell creates specific kind of Co 3 O 4 @SiO 2 nanoreactor. • VOCs combustion reaction can run very effectively inside Co 3 O 4 @SiO 2 nanoreactor. Co 3 O 4 @SiO 2 yolk-shell materials containing Co 3 O 4 nanoparticles protected against aggregation and easily accessible for gaseous reactants inside a mesoporous SiO 2 shell were developed for the catalytic combustion of volatile organic compounds (VOCs). Spherical polymer templates with an appropriate cation adsorption capacity were used as scaffolding for the construction of these structures by the bottom-up strategy. An application of polystyrene led to accumulation of introduced cobalt phase within the SiO 2 layer and favored the formation of catalytically inactive Co silicate species. On the other hand, poly(maleic anhydride- co -divinylbenzene) modified with diethylenetriamine gave improved penetration of the composite interior by Co2+ cations and highly dispersed Co 3 O 4 nanoparticles after calcination. The latter materials appeared excellent nanoreactors for the catalytic combustion of toluene. The real role of the active phase was determined by characterization of the developed catalysts with XRD, N 2 adsorption, SEM-EDS, TEM, UV–Vis-DR, FT-IR, H 2 -TPR, isothermal oxidation-reduction analyses, XPS, XAS and electrochemical measurements. [ABSTRACT FROM AUTHOR] more...
- Published
- 2024
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15. Prospective environmental assessment of technologies for mitigating methane emissions
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Johannisson, Jonas, Hiete, Michael, and Ziegenbalg, Dirk
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Methan ,LCA ,Total oxidation ,Umweltbilanz ,Life Cycle Assessment ,Climate change mitigation ,Emission mitigation ,DDC 570 / Life sciences ,ddc:570 ,Emerging technology ,Fotokatalyse ,Environmental sustainability ,Prospective Life Cycle Assessment ,Photocatalysis ,Methane - Abstract
Climate change is and will continue to impact our everyday lives. Rising methane emissions are contributing a significant share of this problem, as the same mass of methane is 28 times more harmful to the climate than carbon dioxide on a 100-year basis. While natural sinks metabolize methane in such great amounts that there is an equilibrium between natural methane emissions and removal, anthropogenic methane emissions bring an imbalance to this natural system. This imbalance needs to at least be offset and, ideally, overcompensated for, in order to reduce the atmospheric methane concentration to preindustrial levels. Currently, most of the mitigation approaches focus on high-concentrated methane emissions, even though about half of the total methane emissions stem from low-concentrated and spatially distributed sources, which are not currently possible to effectively mitigate. To develop a technical system able to aid in this endeavor, one must establish mitigatable methane sources, determine suitable technologies, and assess the proposed environmental technology. This thesis contributes to the current literature accordingly with three articles dealing with low-concentrated methane emission mitigation. The first research article identifies, from different fields of research, 18 problems currently preventing the mitigation of natural emissions, but also systematically provides answers and assistance in solving those problems. This article clearly lays out that only post-emission methane mitigation seems fit to tackle the identified problems, such as emission sources that are hard to reach or non-confined. The article also proposes multiple mitigation techniques which could be applied independently to the characteristics of the methane emission source and finds that, while valorization opportunities of methane emissions seem more economical, technically, the total oxidation of methane to carbon dioxide is more easily achievable. Moreover, using this conversion from CH 4 to CO 2 up to 90% of the specific climate change impact of methane is mitigatable. One of the proposed technologies is photocatalysis, where low methane concentrations can self-sufficiently be oxidized to carbon dioxide using only sunlight as an energy source. The second article introduces the methodology of life cycle assessment by reporting about a first-in-research case study. Here, students conducted a total of 25 life cycle assessments of meals in a service-learning environment. The use-case of meals was chosen since agricultural methane emissions, which are strongly related to food production, are both one of the largest anthropogenic emission sources as well as one of the hardest to mitigate. The life cycle assessments used an easy-to-understand impact assessment methodology to be able to communicate the results to a broad audience. This is needed for communicating with different fields of research and their individual challenges and solutions for methane mitigation, as described in article 1. Bridging between articles 1, 2, and 3 a qualitative comparison between different technologies used for low-methane mitigation was done. The focus was placed on biocatalysis, catalytic combustion, and photocatalysis. The comparison aimed to investigate advantages and disadvantages of the technologies related to stakeholder requirements and eco-design. It was found that photocatalysis shows the most promising evaluation, as it is the easiest to operate autonomously. Article 3 builds on the foundation laid out by article 1 and article 2. Here, the use of a lab-scale photocatalytic methane mitigation technology is proposed, described, and scaled up to a market-ready version in the year 2050, resulting in a market-ready photocatalytic system designed with CAD. This system is then assessed from an environmental perspective to find out if, and under which circumstances, this technology could be viable in mitigating low- concentrated methane emissions. This assessment builds on a four-step prospective LCA approach. The results show that, depending on the scenario chosen, the technology might be suitable for methane mitigation, as—in the best-case scenario—life cycle greenhouse gas emissions of the technology are amortized after a few years of use. Under more pessimistic considerations, the technology will emit about 50% more greenhouse gases than it can mitigate over its lifetime. Still, in both scenarios, the current physicochemical properties of the photocatalyst, such as reaction rate and lifetime, must be increased by multiple orders of magnitude to be able to achieve these results. Therefore, it can be concluded that, while photocatalysis might be the best option to mitigate low-concentrated methane, the current technical, regulatory, and environmental hurdles might reasonably hinder a large-scale application. Still, this dissertation contributes to the assessment of emerging environmental technologies at a future point in time. This study can be adapted to include new research insights, in a way that, as research continues, more environmentally friendly photocatalysts with improved physicochemical properties might be developed, which could change the assessment drastically. more...
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- 2023
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16. Enhancement of Catalytic Performance of H-Clinoptilolite in Toluene Abatement from Polluted Air via Controlled Dealumination Method.
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Ghasemian, Naser and Yousefi, Ali Reza
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CLINOPTILOLITE , *CATALYSIS , *TOLUENE , *ABATEMENT (Atmospheric chemistry) , *AIR pollutants , *OXALIC acid - Abstract
In this study, the effect of clinoptilolite dealumination on the total oxidation of toluene was reported for the first time. To avoid excess decrease of catalyst crystallinity, chemical modification of zeolite was carried out using a mild acid like oxalic acid. The catalysts were characterized by XRD, XRF, SEM, BET and TPD analyses. It was found that dealumination resulted in a significant enhancement of toluene conversion when 0.050 M acid oxalic was used for a treatment period of 2 h. Dealumination substantially changed the distribution of the concentration of acid sites of different strength and increased the surface area and porosity, so that the temperature corresponding to the maximum conversion shifts around 50 °C towards lower temperatures (in case of CLP 050). The effect of dealumination on the activity of the zeolite samples and the total oxidation of toluene was discussed in terms of Si/Al ratio, crystallinity, distribution of acid site strength and textural characteristics of the samples. [ABSTRACT FROM AUTHOR] more...
- Published
- 2018
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17. Oxidation of Volatile Organic Compounds by Highly Efficient Metal Zeolite Catalysts.
- Author
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Soares, Olívia S. G. P., Fonseca, António M., Parpot, Pier, Órfão, José J. M., Pereira, Manuel F. R., and Neves, Isabel C.
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VOLATILE organic compounds , *OXIDATION , *ZEOLITE catalysts , *POLLUTANTS , *ETHYL acetate - Abstract
Abstract: The presence of two metals (M1M2) in a zeolite structure enhances the degradation of pollutants in liquid or gas phase comparing to monometallic catalysts. In this work, the complete oxidation of ethyl acetate into CO2 was achieved by metal catalysts based on NaY zeolite prepared by the ion‐exchange method. The metal zeolite catalysts were optimized by using several parameters: (i) the presence of a second metal in M1M2 catalysts; (ii) the presence or not of a noble metal in the pair CuM2 (M2=Pd, Zn or Ag); (iii) the order of introduction of the metals in M1M2 catalysts (CuPd or PdCu); (iv) particle size of NaY and NaYnano; and (v) the effect of simultaneously adding metal species (Cu and Pd). M1M2 catalysts presented the best results compared to the monometallic catalysts and the presence of a noble metal in M1M2 catalysts enhanced their acivity. Among the metal phases studied, the catalyst (CuPd)0.01‐Y has shown to be the most efficient for this application. [ABSTRACT FROM AUTHOR] more...
- Published
- 2018
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18. Unravelling the critical role of silanol in Pt/SiO2 for room temperature HCHO oxidation: An experimental and DFT study.
- Author
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Chen, Shuo, Gueddida, Saber, Badawi, Michael, Lebègue, Sébastien, Giraudon, Jean-Marc, Dhainaut, Jérémy, Royer, Sébastien, and Lamonier, Jean-Francois
- Subjects
- *
OXIDATION , *CATALYST testing , *SURFACE interactions , *CATALYTIC activity , *CARBON dioxide , *ACTIVATION energy , *CATALYTIC oxidation - Abstract
In the present work, Pt/SiO 2 catalysts have been prepared by impregnating as-prepared Pt NPs onto commercial SiO 2 of tailored silanol density (2.3, 3.1 and 4.5 OH nm−2) produced through hexamethyldisilazane passivation. The resulting Pt/SiO 2 catalysts were then tested for formaldehyde (HCHO) total oxidation. The catalytic tests showed that high surface silanol density led to lower apparent activation energy (from 40.7 kJ⸱mol−1 at 2.3 OH nm−2 to 21.9 kJ⸱mol−1 at 4.5 OH nm−2)), allowing formaldehyde total oxidation in dry and wet conditions (100% conversion into CO 2 over Pt/SiO 2 (4.5 OH nm−2) at room temperature in dry condition, among the best catalytic performances reported). DFT calculations described the different interaction behaviours of HCHO, H 2 O, CO and CO 2 on pure SiO 2 and Pt/SiO 2 (1.1–7.2 OH nm−2) surface, showing the critical role of silanols in the total oxidation of formaldehyde over Pt/SiO 2 in different humid conditions. [Display omitted] • Pt/SiO 2 design with tailored silanol density for the room temperature formaldehyde oxidation in dry and humid environments. • Pt/SiO 2 with 4.5 OH nm-2 is highly efficient and stable for formaldehyde oxidation at room temperature. • Evidence of critical role of surface hydroxyls in the interaction modes of molecules involved in the reaction. • Reduction of the interaction strength of water molecules with surface of the silanol-rich Pt/SiO 2 catalyst. • In humid environment, a suitable silanol density facilitate water molecule activation and promote the catalytic activity. [ABSTRACT FROM AUTHOR] more...
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- 2023
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19. Influence of Transesterification Catalysts Synthesized with Citric Acid on the Quality and Oxidative Stability of Biodiesel from Black Soldier Fly Larvae
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Lilies K. Kathumbi, Patrick G. Home, James M. Raude, Benson B. Gathitu, Anthony N. Gachanja, Anthony Wamalwa, and Geoffrey Mibei
- Subjects
biodiesel ,Black Soldier Fly Larvae ,catalyst synthesis ,fatty acid methyl esters ,oxidizability index ,physicochemical properties ,total oxidation - Abstract
In biodegradable waste management, use of Black Soldier Fly Larvae (BSFL) is a promising method for bioconversion of waste into crude insect fat as feedstock for biodiesel production. Biodiesel is a renewable alternative to fossil fuel, but it is more susceptible to oxidative degradation over long-term storage. This study investigates the effectiveness of NaOH and CaO catalysts synthesized with citric acid (CA) in improving the oxidative stability of biodiesel. The biodiesel and biodiesel/diesel blends derived from BSFL were stored at 63 °C for 8 days. The quality of biodiesel was determined by analysis of the physicochemical and fuel properties by: Fourier transform infrared (FTIR) spectroscopy, ultraviolet visible spectrophotometer (UV-Vis), gas chromatography-mass spectroscopy (GC-MS), bomb calorimeter and titration methods. Properties that were analyzed included: peroxide value, acid value, iodine value, refractive index, density, calorific value, total oxidation (TOTOX), anisidine value and fatty acid profile. The results showed that catalysts synthesized with CA retarded the decomposition of unsaturated fatty acids, resulting in a significant delay in the formation of hydroperoxides. Besides, 10-oxo-octadecanoic acid, an antioxidant, was present in biodiesel produced using catalysts synthesized with CA, hence enhancing the stability of biodiesel against oxidation. Catalysts synthesized with CA slowed the decomposition of monounsaturated fatty acids by 6.11–11.25%. Overall, biodiesel produced using catalysts synthesized with CA was observed to degrade at a slower rate than biodiesel produced using commercial calcium oxide. The reduced degradation rates demonstrate the effectiveness of the synthesized catalysts in enhancing the oxidation stability and consequently the fuel qualities of biodiesel from BSFL under accelerated storage. more...
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- 2022
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20. Appendix A. Supplementary material for The promoter effect of Nb species on the catalytic performance of Ir-based catalysts for VOCs total oxidation [Dataset]
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Gobierno de Aragón, Agencia Estatal de Investigación (España), Ministerio de Ciencia e Innovación (España), European Commission, Ministerio de Economía y Competitividad (España), Chávez Sifontes, Marvin [0000-0001-8264-291X], García Moreno, Adrián [0000-0002-9530-1230], Furgeaud, Clarisse [0000-0002-6654-396X], Mayoral, Álvaro [0000-0002-5229-2717], Arenal, Raúl [0000-0002-2071-9093], Morgan, David J. [0000-0002-1611-9263], Taylor, Stuart H. [0000-0002-1933-4874], López Sebastián, José Manuel [0000-0002-6203-8835], García Martínez, Tomás [0000-0003-4255-5998], Solsona, Benjamín [0000-0001-7235-2038], García Martínez, Tomás; Solsona, Benjamín, García Moreno, Adrián, Chávez Sifontes, Marvin, Sanchis, Rut, Furgeaud, Clarisse, Mayoral, Álvaro, Arenal, Raúl, Morgan, David J., Taylor, Stuart H., López Sebastián, José Manuel, García Martínez, Tomás, Solsona, Benjamín, Gobierno de Aragón, Agencia Estatal de Investigación (España), Ministerio de Ciencia e Innovación (España), European Commission, Ministerio de Economía y Competitividad (España), Chávez Sifontes, Marvin [0000-0001-8264-291X], García Moreno, Adrián [0000-0002-9530-1230], Furgeaud, Clarisse [0000-0002-6654-396X], Mayoral, Álvaro [0000-0002-5229-2717], Arenal, Raúl [0000-0002-2071-9093], Morgan, David J. [0000-0002-1611-9263], Taylor, Stuart H. [0000-0002-1933-4874], López Sebastián, José Manuel [0000-0002-6203-8835], García Martínez, Tomás [0000-0003-4255-5998], Solsona, Benjamín [0000-0001-7235-2038], García Martínez, Tomás; Solsona, Benjamín, García Moreno, Adrián, Chávez Sifontes, Marvin, Sanchis, Rut, Furgeaud, Clarisse, Mayoral, Álvaro, Arenal, Raúl, Morgan, David J., Taylor, Stuart H., López Sebastián, José Manuel, García Martínez, Tomás, and Solsona, Benjamín more...
- Abstract
Figure S1. XRD patterns of fresh Ir/Nb/Ti catalysts. Figure S2. Figure S3. Cs-corrected STEM-HAADF. Figure S4. O(1s) XPS core-level spectra.
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- 2022
21. The promoter effect of Nb species on the catalytic performance of Ir-based catalysts for VOCs total oxidation
- Author
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Gobierno de Aragón, Ministerio de Ciencia, Innovación y Universidades (España), European Commission, Diputación General de Aragón, Agencia Estatal de Investigación (España), Ministerio de Economía y Competitividad (España), Chávez Sifontes, Marvin [0000-0001-8264-291X], García Moreno, Adrián [0000-0002-9530-1230], Furgeaud, Clarisse [0000-0002-6654-396X], Mayoral, Álvaro [0000-0002-5229-2717], Arenal, Raúl [0000-0002-2071-9093], Morgan, David J. [0000-0002-1611-9263], Taylor, Stuart H. [0000-0002-1933-4874], López Sebastián, José Manuel [0000-0002-6203-8835], García Martínez, Tomás [0000-0003-4255-5998], Solsona, Benjamín [0000-0001-7235-2038], Chávez Sifontes, Marvin, García Moreno, Adrián, Sanchis, Rut, Furgeaud, Clarisse, Mayoral, Álvaro, Arenal, Raúl, Morgan, David J., Taylor, Stuart H., López Sebastián, José Manuel, García Martínez, Tomás, Solsona, Benjamín, Gobierno de Aragón, Ministerio de Ciencia, Innovación y Universidades (España), European Commission, Diputación General de Aragón, Agencia Estatal de Investigación (España), Ministerio de Economía y Competitividad (España), Chávez Sifontes, Marvin [0000-0001-8264-291X], García Moreno, Adrián [0000-0002-9530-1230], Furgeaud, Clarisse [0000-0002-6654-396X], Mayoral, Álvaro [0000-0002-5229-2717], Arenal, Raúl [0000-0002-2071-9093], Morgan, David J. [0000-0002-1611-9263], Taylor, Stuart H. [0000-0002-1933-4874], López Sebastián, José Manuel [0000-0002-6203-8835], García Martínez, Tomás [0000-0003-4255-5998], Solsona, Benjamín [0000-0001-7235-2038], Chávez Sifontes, Marvin, García Moreno, Adrián, Sanchis, Rut, Furgeaud, Clarisse, Mayoral, Álvaro, Arenal, Raúl, Morgan, David J., Taylor, Stuart H., López Sebastián, José Manuel, García Martínez, Tomás, and Solsona, Benjamín more...
- Abstract
Ir/TiO2 catalysts promoted by niobium have been synthesized, characterized by different complementary techniques and tested for the total oxidation of a set of alkanes and their mixtures. The addition of appropriate amounts of niobium to Ir/TiO2 catalysts resulted in a remarkable increase in the catalytic activity compared to the Nb-free Ir/TiO2 catalysts. The promotion caused by the presence of niobium has been related to the massive presence of isolated IrOx surface species which, interestingly, present remarkable reducibility and, consequently, excellent catalytic activity. Conversely, the IrOx species formed in the catalyst in the absence of niobium also include IrO2 clusters with lower intrinsic reactivity. Similarly, Nb-loadings exceeding the theoretical monolayer tends to the formation of bulk Nb2O5 species on the titania surface that provokes the formation of IrO2 nanoclusters. A positive influence on the reactivity of non-stoichiometric surface non- Ti3+ species that generates oxygen vacancies is also observed. more...
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- 2022
22. Combinatorial Methodology and its Experimental Validation by Parallel Synthesis, Testing and Characterization of Solid Catalytic Materials
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Baerns, M., Buyevskaya, O., Grubert, G., Rodemerck, U., Derouane, Eric G., editor, Parmon, Valentin, editor, Lemos, Francisco, editor, and Ribeiro, Fernando Ramôa, editor
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- 2002
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23. The potential use of HNO3-treated clinoptilolite in the preparation of Pt/CeO2-Clinoptilolite nanostructured catalyst used in toluene abatement from waste gas stream at low temperature.
- Author
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Amereh, Majid, Haghighi, Mohammad, and Estifaee, Pooya
- Abstract
In this paper, CeO
2 (30%)/Clinoptilolite was synthesized via HNO3 treatment and coprecipitation methods and then 1% Pt was dispersed over support by ultrasound assisted wet impregnation. The synthesized samples were characterized using XRF, XRD, FESEM, N2 adsorption and FTIR techniques. The obtained results from XRD revealed the main phase in utilized clay is clinoptilolite and also formation of amorphous structure was proved after acid treatment. FESEM micrographs confirmed significant structural changes in clinoptilolite after acid treatment and also formation of ceria nanoparticles. N2 adsorption presented large enough surface area for Pt/CeO2 -Clinoptilolite nanostructured catalyst to be used for toluene oxidation. Finally, activity results indicated that synthesized nanostructured catalyst was highly active and stable and could eliminate more than 90% of toluene at 130 °C. Utilizing inexpensive materials in synthesis and assisting ultrasound in dispersion of active phase have made Pt(1%)/CeO2 (30%)- Clinoptilolite a nominee to be used for catalytic oxidation of toluene. [ABSTRACT FROM AUTHOR] more...- Published
- 2018
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24. Enhanced photo-catalytic activity of TiO2 films by removal of surface carbon impurities; the role of water vapor.
- Author
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Seo, Hyun Ook, Woo, Tae Gyun, Park, Eun Ji, Cha, Byeong Jun, Kim, Il Hee, Han, Sang Wook, and Kim, Young Dok
- Subjects
- *
PHOTOCATALYTIC oxidation , *ACETALDEHYDE , *X-ray photoelectron spectroscopy , *GAS chromatography , *VACUUM chambers - Abstract
We have studied the photo-catalytic degradation of acetaldehyde over the surface of TiO 2 films under UV light (365 nm) irradiation both at dry and humid air conditions using a high vacuum chamber equipped with on-line gas-chromatography as a batch-type reactor. Changes of TiO 2 surfaces upon the photo-catalysis experiments were studied by X-ray photoelectron spectroscopy. The competitive adsorption of water and acetaldehyde resulted in the reduction of reaction rate of photo-catalytic degradation of acetaldehyde under the UV light irradiation. The photo-catalytic reaction rate of TiO 2 films towards acetaldehyde mineralization increased when the photo-catalysis experiments were performed repeatedly and it was much more pronounced under humid conditions. Our XPS analysis revealed that carbon impurities on the surface of TiO 2 films were removed by UV-light driven photo-catalytic mineralization under humid conditions. Water vapor facilitated the photo-catalytic removal of carbon impurities from TiO 2 surface generating additional active sites of TiO 2 which resulted in the enhanced photo-catalytic activity of TiO 2 films. [ABSTRACT FROM AUTHOR] more...
- Published
- 2017
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25. Total oxidation of methane over supported CuO: Influence of the MgxAlyO support.
- Author
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Popescu, Ionel, Tanchoux, Nathalie, Tichit, Didier, and Marcu, Ioan-Cezar
- Subjects
- *
METHANE , *OXIDATION , *ALKANES , *CHEMICAL reactions , *COPPER oxide - Abstract
Copper oxide supported on Al 2 O 3 , MgO and Mg(Al)O mixed oxides with Mg/Al atomic ratios of 1, 3 and 5 were prepared by coprecipitation followed by calcination at 750 °C. These catalysts have been characterized by XRD, EDX, N 2 adsorption, TG-DTG, NH 3 -TPD, CO 2 -TPD and H 2 -TPR, and their catalytic properties in the total oxidation of methane were investigated. Correlations between the physico-chemical properties and the catalytic activities were established. The best activity was obtained for the catalyst presenting a distribution of CuO species going from well distributed and aggregated CuO particles to CuAl 2 O 4 phase on a Mg(Al)O support composed of a mixture of γ-alumina and periclase phases. It also possesses high relative amounts of strong acid and of medium and strong basic sites in this series. All the catalysts tested exhibited very good stabilities for the reaction conditions chosen and time-on-stream up to more than 50 h. [ABSTRACT FROM AUTHOR] more...
- Published
- 2017
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- View/download PDF
26. Self-Sustained Oscillations as a Method to Increase an Active Surface and Catalytic Activity of Ni and Pd.
- Author
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Bychkov, V., Tulenin, Yu., Slinko, M., Sokolov, S., and Korchak, V.
- Subjects
- *
CATALYTIC activity , *PALLADIUM catalysts , *OSCILLATIONS , *NICKEL catalysts , *SURFACE chemistry , *OSCILLATING chemical reactions - Abstract
The effect of Ni and Pd surface development during catalytic self-oscillatory oxidation of C-C alkanes on the activity of these two metals in other catalytic reactions was studied. Scanning electron microscopy investigations revealed that the surface of bulk Ni and Pd (foil or powder) developed significantly faster during alkane oxidation in a self-oscillatory regime than under stationary conditions. Thanks to increase in available metal surface achieved during such self-oscillatory pretreatment, catalytic activity of Ni in methane dry reforming and in ethylene hydrogenation and that of Pd in total methane oxidation increased by an order of magnitude compared to the untreated metals. With time on stream, the activity dropped to some stationary level that was still significantly higher than the activity of the fresh metals. Morphological changes of Ni during the pretreatment were caused by periodic oxidation-reduction of the surface atomic layers whereas in case of Pd redox cycles were accompanied by carbon dissolution-removal. The amount of carbon dissolved in Pd during self-oscillatory oxidation of C-C alkanes decreased with increasing chain length, likewise the metal surface development. Supported Pd/AlO catalyst did not exhibit significant activity changes after the self-oscillatory pretreatment suggesting that the morphology of Pd particles remained unaltered. Graphical Abstract: [ABSTRACT FROM AUTHOR] more...
- Published
- 2017
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- View/download PDF
27. Comparative sonochemically synthesis of CeO2-doped Pd/clinoptilolite and Pd/Al2O3 nanocatalysts used in total oxidation of toluene at low temperatures for polluted air treatment.
- Author
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Hosseini, Maryam, Haghighi, Mohammad, Margan, Payam, and Ajamein, Hossein
- Subjects
- *
PALLADIUM catalysts , *CATALYST synthesis , *CERIUM oxides , *ALUMINUM oxide , *OXIDATION of toluene , *AIR pollution - Abstract
A series of palladium based nanocatalysts which were loaded on CeO2 doped alumina or clinoptilolite supports were synthesized by the ultrasonic assisted impregnation method. The influence of different ceria doped supports via total oxidation of toluene was investigated. Therefore, physiochemical properties of prepared nanocatalysts were evaluated by XRD, FESEM, BET and FTIR analyses. The FESEM images stated that synthesized naocatalysts had nanometric particles. The average size of catalyst particle was obtained to be 34.5 nm. BET analysis introduced a considerable rise in clinoptilolite surface area after treatment and demonstrated large surface area for Al2O3 and its composites. CeO2 acts not only as a fine support due to its stability and surface area, but also had catalytic role because of its reducibility properties. Among synthesized catalysts, Pd/Al2O3-CeO2 sample resulted the lowest particle size, highest surface area and consequently highest oxidation performance and stability. [ABSTRACT FROM AUTHOR] more...
- Published
- 2017
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28. Influence of active phase composition (Mn, Ni, MnxNi10-x) on catalytic properties and performance of clinoptilolite supported nanocatalysts synthesized using ultrasound energy toward abatement of toluene from polluted air.
- Author
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Ahmadi, Maryam, Haghighi, Mohammad, and Kahforoushan, Dauood
- Subjects
- *
CATALYST synthesis , *CLINOPTILOLITE , *CATALYST supports , *CATALYSIS , *OXIDATION of toluene - Abstract
Toluene removal out of waste gas streams was fulfilled through catalytic oxidation over series of MnxNi10-x/clinoptilolite nanocatalysts with different Mn/Ni ratios. The samples were synthesized using sonochemical method and examined in total oxidation of toluene. The nanocatalysts were characterized by XRD, FESEM, EDX, FTIR and BET techniques. XRD data was confirmed the formation of Mn2O3 and NiO as the crystalline phases for single and mixed oxides nanocatalysts. Furthermore, EDX analysis manifested homogenous dispersion of elements on ultrasound irradiated nanocatalysts. Basically, reaction data illustrated that all bimetallic nanocatalysts had lower temperature activity compared to monometallic nanocatalysts. Results indicated that there are significant synergetic effects of bimetallic on reduction of oxidation temperature. Mn7%Ni3%/clinoptilolite nanocatalyst had the best performance among synthesized samples. Toluene removal efficiency on this nanocatalyst was completed at 225 °C. Stability test of nanocatalyst demonstrated that the removal efficiency has remained constant for 1440 min. [ABSTRACT FROM AUTHOR] more...
- Published
- 2017
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29. Sono-dispersion of ceria and palladium in preparation and characterization of Pd/Al2O3-clinoptilolite-CeO2 nanocatalyst for treatment of polluted air via low temperature VOC oxidation.
- Author
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Hosseini, Maryam, Haghighi, Mohammad, Kahforoushan, Davood, and Zarrabi, Mahdi
- Subjects
- *
CATALYST synthesis , *PALLADIUM catalysts , *NANOSTRUCTURED materials , *AIR pollution , *ALUMINUM oxide , *CERIUM oxides - Abstract
Pd/Al2O3-clinoptilolite-CeO2 nanocatalyst was successfully synthesized via ultrasound assisted wet impregnation method to be utilized for total oxidation of toluene. Chemical analysis like XRD, FESEM, EDX, BET and FTIR techniques are used to determine physicochemical properties of synthesized samples. Chemical analysis confirms the presence of all the elements in natural and treated clinoptilolite. XRD patterns prove the formation of ceria as a crystalline phase with an average crystallite size of 19.5 nm. FESEM images show the surface nanometric size of catalyst particles. EDX analysis indicates homogeneous dispersion of elements over nanocatalyst. BET surface area presented large surface for nanocatalysts. The results confirm the positive effect of ultrasound irradiation on surface morphology and elemental dispersion. Catalytic performance tests indicated high removal efficiency of nanocatalyst in total oxidation of toluene. High conversion at low temperatures (200-225 °C) and thermal stability are reasons for this observation. [ABSTRACT FROM AUTHOR] more...
- Published
- 2017
- Full Text
- View/download PDF
30. Decreasing CoO Particle Sizes by Ammonia-Etching and Catalytic Oxidation of Propane.
- Author
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Zhang, Weidong, Hu, Lijuan, Wu, Feng, and Li, Jinjun
- Subjects
- *
NANOSTRUCTURED materials synthesis , *SIZE reduction of materials , *COBALT oxides , *AMMONIA , *METAL etching , *CATALYTIC oxidation , *OXIDATION of propane - Abstract
Nanosized cobalt oxides were synthesized by ammonia-etching of cobalt hydroxide and subsequent calcination. The effects of ammonia etching on the structures and catalytic properties of cobalt oxide were investigated. The results suggested that the cobalt oxide is composed of cubic CoO having particle sizes in the range of 10-20 nm; smaller than the analogue prepared through the conventional precipitation method. Ammonia etching improved the reducibility of cobalt oxide, and facilitated the generation of surface oxygen vacancies and the production of surface-adsorbed active oxygen species. The activity of CoO in propane oxidation was greatly enhanced by ammonia etching, mainly due to the smaller particle size and better redox properties. The facile ammonia-etching synthesis method has potential for large-scale and low-cost production of cobalt oxide catalyst. Graphical Abstract: [ABSTRACT FROM AUTHOR] more...
- Published
- 2017
- Full Text
- View/download PDF
31. Experimental study on a methanol auto-thermal reforming for compact reformer
- Author
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Jun OHTANI, Takahiro SAKAMOTO, Masayoshi WADA, Hasan Mohd FAIZAL, Takeshi YOKOMORI, and Toshihisa UEDA
- Subjects
methanol ,steam reforming ,partial oxidation ,total oxidation ,auto-thermal reforming ,hydrogen ,oxygen/carbon ratio ,steam/carbon ratio ,Mechanical engineering and machinery ,TJ1-1570 - Abstract
Performance of self-sustaining methanol auto-thermal reforming (ATR) was investigated experimentally in order to elucidate a reforming reaction mechanism and a condition required for high purity H2 production for compact reformer. The reformer consists of vaporizing and reforming sections in a single unit. The exothermic oxidation and endothermic steam reforming (STR) take place simultaneously in the reforming section. The reforming section is surrounded by the vaporizing section and then the heat for vaporization is supplied from the reforming section. Two types of exothermic oxidation reaction were investigated as the heat source for STR; one is a partial oxidation (POX) and the other is a total oxidation (TOX). CuO/ZnO/Al2O3 catalyst and Pt/Al2O3 catalyst were used for STR and POX, respectively. While, only CuO/ZnO/Al2O3 catalyst was needed for TOX because TOX took place when fuel and oxygen were supplied to the CuO/ZnO/Al2O3 catalyst. Experiments were investigated in the range of oxygen/carbon ratio (O/C ratio) 0.1-1.5, steam/carbon ratio (S/C ratio) 1.0-3.0 and N2 mole ratio 79-50 % in oxidizer. The results showed that the H2 formation reached maximum at around O/C=0.4 in both STR/POX and STR/TOX cases in the present study. When O/C ratio is decreased from 0.4, heat formation by the oxidation reactions decreases and is insufficient to reform residual CH3OH by STR. As a result, H2 formation and the methanol conversion ratio decrease. When O/C ratio is increased from 0.4, the H2 formation decreases, because methanol is consumed with the excess O2 by TOX and CH3OH for STR decreases. After all, O/C=0.4 gives an appropriate balance of heat supply and methanol for H2 production. These results elucidate that the reaction rate of oxidation reactions, POX and TOX, is much faster than that of STR. In other words, methanol is first consumed by the oxidation reaction and the residual methanol is used for STR. For S/C ratio, H2 formation is decreased in the higher S/C ratio. N2 mole ratio in oxidizer has few influence over the reforming gas. The chemical equilibrium calculations support the experimental results. more...
- Published
- 2016
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32. Recognition of B vs. Z-Form DNA Using Nickel and Cobalt Complexes
- Author
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Burrows, Cynthia J., Muller, James G., Shih, Hui-Chen, Rokita, Steven E., and Siegel, Jay S., editor
- Published
- 1995
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33. Techniques of Preparation of Thin Films: Catalytic Combustion
- Author
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Marius Stoian, Thomas Maurer, Salim Lamri, Ioana Fechete, University of Bucharest (UniBuc), Lumière, nanomatériaux et nanotechnologies (L2n), Université de Technologie de Troyes (UTT)-Centre National de la Recherche Scientifique (CNRS), Laboratoire des Systèmes Mécaniques et d'Ingénierie Simultanée (LASMIS), and Université de Technologie de Troyes (UTT) more...
- Subjects
Chemistry ,[SPI]Engineering Sciences [physics] ,total oxidation ,methane ,Chemical technology ,TP1-1185 ,Physical and Theoretical Chemistry ,thin film catalysts ,environment ,QD1-999 ,Catalysis ,carbon monoxide - Abstract
International audience; Over the past several decades, an increasing amount of attention has been given to catalytic combustion as an environmentally friendly process. However, major impediments to large-scale application still arise on the materials side. Here, we review catalytic combustion on thin film catalysts in view of highlighting some interesting features. Catalytic films open the way for new designs of structured catalysts and the construction of catalysts for catalytic combustion. A special place is occupied by materials in the form of very thin films that reveal catalytic activity for various chemical reactions. In this review, we demonstrate the high catalytic activity of thin film catalysts in these oxidation reactions. more...
- Published
- 2021
- Full Text
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34. Highly Active Co3O4-Based Catalysts for Total Oxidation of Light C1–C3 Alkanes Prepared by a Simple Soft Chemistry Method: Effect of the Heat-Treatment Temperature and Mixture of Alkanes
- Author
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Adrián García, Benjamín Solsona, Francisco Ivars-Barceló, Rut Sanchis, María Isabel Vázquez, Stuart Hamilton Taylor, Tomás García, Ana Dejoz, Ministerio de Ciencia, Innovación y Universidades (España), European Commission, Agencia Estatal de Investigación (España), Comunidad de Madrid, García Moreno, Adrián, Ivars-Barceló, F., Taylor, Stuart H., García Martínez, Tomás, Dejoz, Ana, Solsona, Benjamín, García Moreno, Adrián [0000-0002-9530-1230], Ivars-Barceló, F. [0000-0002-5896-7623], Taylor, Stuart H. [0000-0002-1933-4874], García Martínez, Tomás [0000-0003-4255-5998], Dejoz, Ana [0000-0002-1600-8803], and Solsona, Benjamín [0000-0001-7235-2038] more...
- Subjects
inorganic chemicals ,Technology ,Inorganic chemistry ,Total oxidation ,cobalt oxide ,chemistry.chemical_element ,alkane oxidation ,propane ,Heterogeneous catalysis ,surface oxygen vacancies ,Methane ,Article ,Catalysis ,chemistry.chemical_compound ,Propane ,Alkane oxidation ,Surface oxygen vacancies ,total oxidation ,volatile organic compounds ,General Materials Science ,Reactivity (chemistry) ,Volatile organic compounds ,Cobalt oxide ,Alkane ,chemistry.chemical_classification ,Ethane ,Microscopy ,QC120-168.85 ,methane ,QH201-278.5 ,ethane ,Engineering (General). Civil engineering (General) ,TK1-9971 ,heterogeneous catalysis ,chemistry ,Descriptive and experimental mechanics ,Mixed oxide ,Electrical engineering. Electronics. Nuclear engineering ,TA1-2040 ,Cobalt - Abstract
9 figures, 2 tables., In the present work, a simple soft chemistry method was employed to prepare cobalt mixed oxide (Co3O4) materials, which have shown remarkably high activity in the heterogeneously catalyzed total oxidation of low reactive VOCs such as the light alkanes propane, ethane, and methane. The optimal heat-treatment temperature of the catalysts was shown to depend on the reactivity of the alkane studied. The catalytic activity of the Co3O4 catalysts was found to be as high as that of the most effective catalysts based on noble metals. The physicochemical properties, from either the bulk (using XRD, TPR, TPD-O2, and TEM) or the surface (using XPS), of the catalysts were investigated to correlate the properties with the catalytic performance in the total oxidation of VOCs. The presence of S1 low-coordinated oxygen species at the near surface of the Co3O4-based catalysts appeared to be linked with the higher reducibility of the catalysts and, consequently, with the higher catalytic activity, not only per mass of catalyst but also per surface area (enhanced areal rate). The co-presence of propane and methane in the feed at low reaction temperatures did not negatively affect the propane reactivity. However, the co-presence of propane and methane in the feed at higher reaction temperatures negatively affected the methane reactivity., This research was funded by MINECO-Spain, grant number PRE2018-085211. This work was also funded by the MAT2017-84118-C2-1-R MCIN/AEI/10.13039/501100011033/ project and FEDER Una manera de hacer Europa. Comunidad de Madrid, grant number 2017-T1/IND-6025, within the program “Atracción y Retención de Talento Investigador” of the V PRICIT. more...
- Published
- 2021
- Full Text
- View/download PDF
35. Structure and reactive properties of Nb-impregnated two-dimensional pillared MWW zeolites for total oxidation of volatile organic compounds
- Author
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Christian W. Lopes, Urbano Díaz, Anderson Joel Schwanke, Rosana Balzer, Debora Motta Meira, Katia Bernardo-Gusmão, Sibele B. C. Pergher, and Ministerio de Economía y Competitividad (España)
- Subjects
Chemistry ,Niobium ,Inorganic chemistry ,Xylene ,Total oxidation ,chemistry.chemical_element ,Pillared zeolites ,General Chemistry ,Condensed Matter Physics ,Toluene ,Catalysis ,chemistry.chemical_compound ,MCM-36 ,Octahedron ,Mechanics of Materials ,General Materials Science ,Volatile organic compounds ,Zeolite ,Benzene ,Mesoporous material - Abstract
In this work, the structure and reactive properties of niobium (Nb)-impregnated MWW-type materials were evaluated for gas-phase total oxidation of volatile organic compounds, including BTX (benzene, toluene and o -xylene). The role of the type of structure (two or three-dimensional) and the loading of Nb were considered. The results indicated most Nb species with a tetrahedral coordination on the external surfaces of both two- and three-dimensional zeolites, together with a minimal contribution of octahedral extra-framework NbO species. The texture and Nb content played a key role in the gas-phase total oxidation of BTX. With the same Nb content (5 wt%), the pillared zeolite exhibited a higher specific surface, larger pore volume and mesopores between the MWW nanosheets when compared to the MCM-22 zeolites, which resulted in high accessibility of the reactant molecules to the active sites, reflected in higher BTX conversion at lower and higher temperatures (50–300 °C). The best performance was achieved with the pillared zeolite (10 wt% Nb), reaching a BTX conversion at 300 °C of 92%, 69% and 58%, respectively. The catalyst was stable for up to 30 h of reaction., A.J.S. thanks the Cordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES, Brazil; Finance Code 001) and the Programa de Pós-Graduação em Química of the Universidade Federal do Rio Grande do Sul (PPGQ-UFRGS). C.W.L. thanks the PRH 50.1 – ANP/FINEP Human Resources Program for the Visiting Researcher Fellowship. This research used resources of the Advanced Photon Source, a user facility operated for the U.S. Department of Energy (DOE) Office of Science by Argonne National Laboratory, and was supported by the U.S. DOE under Contract No. DE-AC02-06CH11357 and by the Canadian Light Source and its funding partners. U.D thanks the MAT2017-82288-C2-1-P Project. more...
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- 2021
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36. Elimination of 1,2-dichloroethane over (Ce,Cr)xO2/MOy catalysts (M = Ti, V, Nb, Mo, W and La).
- Author
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Yang, Peng, Zuo, Shufeng, Shi, Zhinan, Tao, Fei, and Zhou, Renxian
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CATALYSTS , *CATALYSIS , *ALUMINUM catalysts , *BASE catalysts , *CATALYST pretreatment - Abstract
(Ce,Cr) x O 2 /MO y (M = Ti, V, Nb, Mo, W, La, respectively) mixed oxides are synthesized by deposition-precipitation method, and evaluated for total oxidation of gaseous 1,2-dichloroethane, a typical chlorinated organic pollutant. The characterization results show that there exists strong metal-support interaction or synergistic effect between (Ce,Cr) x O 2 and MO y . The catalytic performances of these catalysts can be related to the nature of each MO y support, the crystal structure and composition, the surface elements distribution and the diverse redox properties of (Ce,Cr) x O 2 /MO y . The improved redox property, as well as the increased content of Ce 3+ and Cr 6+ species on the surface can enhance the catalytic performances of the catalysts. Especially, (Ce,Cr) x O 2 /Nb 2 O 5 exhibits the best catalytic performance. (Ce,Cr) x O 2 /Nb 2 O 5 also represents high durability for 1,2-dichloroethane oxidation during the long-term continuous test. Moreover, though the presence of water or benzene in the reaction system slightly suppresses 1,2-dichloroethane oxidation, the catalytic activity can be recovered by the cut of water, while a little deactivation is found if benzene is removed away, since coke has been deposited on the catalyst surface by the combustion of benzene. [ABSTRACT FROM AUTHOR] more...
- Published
- 2016
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37. Modification of Y Faujasite zeolites for the trapping and elimination of a propene-toluene-decane mixture in the context of cold-start.
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Westermann, A., Azambre, B., Chebbi, M., and Koch, A.
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ZEOLITE Y , *ELIMINATION reactions , *PROPANE , *TOLUENE , *MIXTURES , *COPPER ions - Abstract
The modification of a HY zeolite (with Si/Al ratio = 2.5) by impregnation with a platinum salt or ion exchange with Cu 2+ cations was carried out in order to evaluate the potential interest of the obtained materials as hydrocarbon traps for cold-start application. Textural, structural and chemical characterizations were carried out using N 2 adsorption isotherms at −196 °C, XRD and DRIFTS of adsorbed CO and NO. Acidic properties of the parent H/Y and Cu- and Pt-modified zeolites were determined using FTIR of adsorbed pyridine. The methodology used to investigate the adsorption behaviour of the parent and modified HY zeolites consisted in: (i) analysing qualitatively and quantitatively the breakthrough curves obtained at 35 °C during the adsorption of a ternary hydrocarbon mixture (propene, toluene, decane) as well as the data from subsequent temperature-programmed experiments (TPD under He or TPSR in presence of 10%O 2 or 10%O 2 /0.2%NO) (ii) establishing relationships between adsorption/reactivity data and the structural, textural and chemical properties of the modified zeolites. Namely, the introduction of copper and platinum species considerably improves the adsorption of unsaturated hydrocarbons, such as propene or toluene, at the expense of decane. This results in a more adequate balance between all the hydrocarbons adsorbed, which is required for cold-start application. In addition, Cu/Y and Pt/Y zeolites were also found to be efficient for the removal of NOx or HC total oxidation, respectively. [ABSTRACT FROM AUTHOR] more...
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- 2016
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38. Quality assessment of mustard oil in deep fat frying.
- Author
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Nayak, Prakash Kumar, Dash, Uma, and Rayaguru, Kalpana
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QUALITY control , *MUSTARD oils , *DEEP frying , *FLAVOR , *CHEMICAL reactions , *FREE fatty acids , *PEROXIDES , *ANISIDINE - Abstract
Now a days fried foods are very common everywhere around the world and it can be observed by the increasing number of fast food restaurants in the last few decades. Deep frying of foods at high temperature enhances the sensorial properties which include the unique fried flavor, golden brown colour and crispy texture. At the same time, so many chemical reactions like oxidation, polymerization, hydrolysis, etc., take place in the food system, which ultimately alters the physical and chemical properties of fat. Mustard oil is a vegetable oil which is widely being used in India for cooking purpose. The parameters like free fatty acid (FFA), peroxide value (PV), p-anisidine value (p-AV), total oxidation (TOTOX value), iodine value (IV) and colour are studied in this experiment. The heating oil parameter has been taken in such a way, considering the frying practices done in the restaurants of North-East India. The oil sample was taken after every 5 hours of heating mustard oil in deep fat fryer. The 30 hours of heating (5h/day) degrades mustard oil to such an extent that it becomes unadvisable for human consumption. The study showed that there is ample change in the chemical composition and the hunter colour showed that the oil has lost its luster and has become dark red. [ABSTRACT FROM AUTHOR] more...
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- 2016
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39. Total oxidation of toluene over gold supported on mesoporous ferrisilicates materials.
- Author
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Benais-Hamidi, Faiha, Leïla, Chérif-Aouali, Siffert, Stéphane, Cousin, Renaud, and Bengueddach, Abdelkader
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MESOPOROUS silica ,COPOLYMERS ,OXIDATION of toluene - Abstract
Mesoporous ferrisilicates MFS-n (n = Si/Fe) with different Si/Fe molar ratio (Si/Fe = 20, 135) were synthesised by the assembly of Fe MFI nanoclusters with triblock copolymers in strongly acidic media. Au/MFS-n catalysts were prepared by deposition-precipitation with urea (DPU) with a loading of gold of 1 wt%. They were characterised by various techniques including XRD, BET, FT-IR spectroscopy; diffuse reflectance UV-vis (DRUV-vis), TPR. Total oxidation of toluene was investigated on MFS-n and Au/MFS-n. The catalytic activity of MFS-n materials for total toluene oxidation is considerably enhanced as the iron content increases. The presence of gold improves the catalytic activity of MFS-n towards the combustion of toluene, the extent of this effect depending on the Si/Fe molar ratio. The catalysts are totally selective for CO
2 and H2 O. [ABSTRACT FROM AUTHOR] more...- Published
- 2016
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40. Comparative Life Cycle Assessment (LCA) of Two On-Site Small-Scale Activated Sludge Total Oxidation Systems in Plastic and Vibrated Reinforced Concrete.
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De Feo, Giovanni, Ferrara, Carmen, and Iuliano, Giovanni
- Abstract
This study proposes a comparison of the environmental impacts calculated with the Life Cycle Assessment (LCA) methodology of two on-site small-scale activated sludge total oxidation systems in linear low-density polyethylene (LLDPE) and vibrated reinforced concrete (VRC). The plants were designed to ensure a treatment capacity of 5,10,20 and 30 equivalent inhabitants (PE). The main aim of the study was to evaluate the incidence of construction, disposal and operation phases on the total impacts evaluated with three different methods: ReCiPe 2008, Ecological Footprint and IPCC 2007 100 years. The most significant phase for both treatment lines was the use phase, which contributed more than 80% to the total impacts. The construction phase was the second most impactful phase with an incidence less than 25% for both systems and for all the considered impacts assessment methods. The plant in LLDPE was more eco-friendly than that in (VRC). The plant in VRC was always most impactful, even comparing each single phase of the life cycle and for all the treatment capacities taken into consideration. Finally, the obtained results were not dependent on the impact assessment method considered. [ABSTRACT FROM AUTHOR] more...
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- 2016
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41. Oxidation levels of North American over-the-counter n-3 (omega-3) supplements and the influence of supplement formulation and delivery form on evaluating oxidative safety
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Stefan A. Jackowski, Azhar Z. Alvi, Abdur Mirajkar, Zahabia Imani, Yuliya Gamalevych, Nisar A. Shaikh, and George Jackowski
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PUFA ,Peroxides ,Anisidine ,Total oxidation ,n-3 Supplements ,Omega-3 supplements ,Nutrition. Foods and food supply ,TX341-641 ,Medicine - Abstract
The aim of the present study was to evaluate the oxidation status of North American n-3 (omega-3) PUFA nutritional supplements commercially available in Canada and evaluate the influence of product formulation and delivery form on oxidative safety. A total of 171 North American over-the-counter n-3 PUFA nutritional supplements were analysed for oxidation safety. Primary and secondary oxidation and total oxidation (TOTOX) were determined using the American Oil Chemists’ Society (AOCS) procedures. Comparisons between supplements’ final forms, oil source and n-3 PUFA concentration quartiles, as measures of product formulations and delivery forms, were compared using ANOVA. Of the products successfully tested, 50 % exceeded the voluntary recommended levels for markers of oxidation. Another 18 % of products were approaching the limits with 1–3 years before expiration. Encapsulated products without flavour additives had significantly lower secondary and TOTOX levels than bulk oils and flavoured products (P 0·05), with the exception of krill oil products having higher secondary oxidation levels than plant-based products (P > 0·05). Markers of oxidation did not differ between n-3 PUFA supplement concentration quartiles. Consumers may be at risk of exposure to higher levels of oxidative products. New regulatory mandates need to be introduced to ensure that all n-3 PUFA products, used as nutritional supplements, regardless of their formulation or delivery form, can be tested for oxidative safety and compliance. more...
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- 2015
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42. Size-activity relationship of iridium particles supported on silica for the total oxidation of volatile organic compounds (VOCs)
- Author
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Laura Torrente-Murciano, Vicenta González-Alfaro, Rut Sanchis, Benjamín Solsona, Tomás García, Said Agouram, Lukas Schick, José Manuel López, Ministerio de Ciencia, Innovación y Universidades (España), Universidad de Valencia, Gobierno de Aragón, Agouram, S. [0000-0002-9906-1174], López Sebastián, José Manuel [0000-0002-6203-8835], Torrente-Murciano, Laura [0000-0002-7938-2587], García Martínez, Tomás [0000-0003-4255-5998], Solsona, Benjamín [0000-0001-7235-2038], Agouram, S., López Sebastián, José Manuel, Torrente-Murciano, Laura, García Martínez, Tomás, Solsona, Benjamín, and Apollo - University of Cambridge Repository more...
- Subjects
General Chemical Engineering ,Total oxidation ,Inorganic chemistry ,Short chain alkanes ,chemistry.chemical_element ,02 engineering and technology ,Iridium ,010402 general chemistry ,01 natural sciences ,Redox ,Industrial and Manufacturing Engineering ,law.invention ,Catalysis ,Metal ,Size-activity relationship ,law ,Environmental Chemistry ,Calcination ,VOC ,Silica ,General Chemistry ,021001 nanoscience & nanotechnology ,0104 chemical sciences ,chemistry ,visual_art ,visual_art.visual_art_medium ,Particle size ,0210 nano-technology ,Platinum ,Palladium - Abstract
12 Figures, 2 Tables.-- Datos suplementarios disponibles en línea en la página web del editor.-- © 2019. This manuscript version is made available under the CC-BY-NC-ND 4.0 license http://creativecommons.org/licenses/by-nc-nd/4.0/, This systematic catalytic study reveals for the first time a strong size-activity relationship of iridium-based catalysts for the total oxidation of short chain alkanes reaction. Silica has been selected as support for its inertness and weak silica-iridium interaction to avoid its contribution to the catalytic activity. The size of the iridium particles can be increased from ∼5 to 27 nm by increasing the calcination temperature from 350 to 750 °C. Unlike other precious metals such as palladium or platinum, in the case of iridium catalysts, the oxidation activity increases when the size decreases. This effect is also maintained when the activity is normalized per metallic surface area revealing a higher intrinsic activity as the iridium size decreases beyond its simple increase in metallic surface area. Indeed, as the particle size decreases, a higher proportion of highly reducible iridium species as well as an increase in defective Ir3+ species on the surface is observed by XPS, directly related to the enhanced activity. The highly reducible species are oxidized under the reaction conditions, leading to an initial decrease in activity before reaching a stable rate of oxidation reaction. This knowledge provides useful guidelines for the design of iridium-based systems for the total oxidation of volatile organic compounds at low temperatures., Authors from UV thank the University of Valencia (UV-INV-AE16-484416 project) and MINECO (MAT2017-84118-C2-1-R project) for funding. Mathias Van de Vyver is acknowledged for the Raman study. T.G. would also like to thank the Regional Government of Aragón (DGA) for the support provided under the research groups support programme. more...
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- 2019
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43. The promoter effect of Nb species on the catalytic performance of Ir-based catalysts for VOCs total oxidation
- Author
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Marvin Chávez-Sifontes, Adrián García, Rut Sanchis, Clarisse Furgeaud, Alvaro Mayoral, Raul Arenal, David J. Morgan, Stuart H. Taylor, Jose Manuel López, Tomás García, Benjamín Solsona, Gobierno de Aragón, Ministerio de Ciencia, Innovación y Universidades (España), European Commission, Diputación General de Aragón, Agencia Estatal de Investigación (España), Ministerio de Economía y Competitividad (España), Chávez Sifontes, Marvin [0000-0001-8264-291X], García Moreno, Adrián [0000-0002-9530-1230], Furgeaud, Clarisse [0000-0002-6654-396X], Mayoral, Álvaro [0000-0002-5229-2717], Arenal, Raúl [0000-0002-2071-9093], Morgan, David J. [0000-0002-1611-9263], Taylor, Stuart H. [0000-0002-1933-4874], López Sebastián, José Manuel [0000-0002-6203-8835], García Martínez, Tomás [0000-0003-4255-5998], Solsona, Benjamín [0000-0001-7235-2038], Chávez Sifontes, Marvin, García Moreno, Adrián, Furgeaud, Clarisse, Mayoral, Álvaro, Arenal, Raúl, Morgan, David J., Taylor, Stuart H., López Sebastián, José Manuel, García Martínez, Tomás, and Solsona, Benjamín more...
- Subjects
Titania ,Niobium ,Process Chemistry and Technology ,Total oxidation ,Alkane ,VOCs ,Chemical Engineering (miscellaneous) ,Iridium ,Pollution ,Waste Management and Disposal - Abstract
12 figures, 2 tables.-- Supporting information available., Ir/TiO2 catalysts promoted by niobium have been synthesized, characterized by different complementary techniques and tested for the total oxidation of a set of alkanes and their mixtures. The addition of appropriate amounts of niobium to Ir/TiO2 catalysts resulted in a remarkable increase in the catalytic activity compared to the Nb-free Ir/TiO2 catalysts. The promotion caused by the presence of niobium has been related to the massive presence of isolated IrOx surface species which, interestingly, present remarkable reducibility and, consequently, excellent catalytic activity. Conversely, the IrOx species formed in the catalyst in the absence of niobium also include IrO2 clusters with lower intrinsic reactivity. Similarly, Nb-loadings exceeding the theoretical monolayer tends to the formation of bulk Nb2O5 species on the titania surface that provokes the formation of IrO2 nanoclusters. A positive influence on the reactivity of non-stoichiometric surface non- Ti3+ species that generates oxygen vacancies is also observed., This work was supported by the Regional Government of Aragon (DGA) under the research groups support programme. We also thank the MAT2017-84118-C2-1-R MCIN/AEI/10.13039/501100011033/ project and FEDER “Una manera de hacer Europa”. This research was also funded by MINECO-Spain, grant number PRE2018-085211. more...
- Published
- 2022
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44. Highly active Co3O4-based catalysts for total oxidation of light C1-C3 alkanes prepared by a simple soft chemistry method: effect of the heat-treatment temperature and mixture of alkanes
- Author
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Ministerio de Ciencia, Innovación y Universidades (España), European Commission, Agencia Estatal de Investigación (España), Comunidad de Madrid, García Moreno, Adrián [0000-0002-9530-1230], Ivars-Barceló, F. [0000-0002-5896-7623], Taylor, Stuart H. [0000-0002-1933-4874], García Martínez, Tomás [0000-0003-4255-5998], Dejoz, Ana [0000-0002-1600-8803], Solsona, Benjamín [0000-0001-7235-2038], Sanchis, Rut, García Moreno, Adrián, Ivars-Barceló, F., Taylor, Stuart H., García Martínez, Tomás, Dejoz, Ana, Vázquez, Isabel, Solsona, Benjamín, Ministerio de Ciencia, Innovación y Universidades (España), European Commission, Agencia Estatal de Investigación (España), Comunidad de Madrid, García Moreno, Adrián [0000-0002-9530-1230], Ivars-Barceló, F. [0000-0002-5896-7623], Taylor, Stuart H. [0000-0002-1933-4874], García Martínez, Tomás [0000-0003-4255-5998], Dejoz, Ana [0000-0002-1600-8803], Solsona, Benjamín [0000-0001-7235-2038], Sanchis, Rut, García Moreno, Adrián, Ivars-Barceló, F., Taylor, Stuart H., García Martínez, Tomás, Dejoz, Ana, Vázquez, Isabel, and Solsona, Benjamín more...
- Abstract
In the present work, a simple soft chemistry method was employed to prepare cobalt mixed oxide (Co3O4) materials, which have shown remarkably high activity in the heterogeneously catalyzed total oxidation of low reactive VOCs such as the light alkanes propane, ethane, and methane. The optimal heat-treatment temperature of the catalysts was shown to depend on the reactivity of the alkane studied. The catalytic activity of the Co3O4 catalysts was found to be as high as that of the most effective catalysts based on noble metals. The physicochemical properties, from either the bulk (using XRD, TPR, TPD-O2, and TEM) or the surface (using XPS), of the catalysts were investigated to correlate the properties with the catalytic performance in the total oxidation of VOCs. The presence of S1 low-coordinated oxygen species at the near surface of the Co3O4-based catalysts appeared to be linked with the higher reducibility of the catalysts and, consequently, with the higher catalytic activity, not only per mass of catalyst but also per surface area (enhanced areal rate). The co-presence of propane and methane in the feed at low reaction temperatures did not negatively affect the propane reactivity. However, the co-presence of propane and methane in the feed at higher reaction temperatures negatively affected the methane reactivity. more...
- Published
- 2021
45. Co–Mn-oxide spinel catalysts for CO and propane oxidation at mild temperature.
- Author
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Faure faure.benjamin.n@gmail.com, Benjamin and Alphonse, Pierre
- Subjects
- *
SPINEL , *RADIOENZYMATIC assays , *OXIDATION , *PROPANE , *TEMPERATURE control - Abstract
Co x Mn 3− x O 4 oxides (0 ≤ x ≤ 3) were prepared by controlled decomposition of mixed oxalates near 200 °C, followed by a calcination at 300 °C. These oxides are amorphous for x < 0.9. For higher cobalt fraction they have a cubic spinel structure and their crystallite size grows with the cobalt fraction. These materials have a large surface area; the highest values, exceeding 250 m 2 /g, were obtained for x ≈ 2. The spinel oxides exhibit an outstanding catalytic activity for propane oxidation at mild temperature (20–200 °C). They are also active for CO oxidation at ambient temperature. This high activity was correlated both with the surface area and the cobalt concentration. The most efficient material is Co 2,3 Mn 0,7 O 4 , which has a better activity than cobalt oxide catalysts reported in the literature. [ABSTRACT FROM AUTHOR] more...
- Published
- 2016
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46. Microkinetics for toluene total oxidation over CuO–CeO2/Al2O3.
- Author
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Menon, Unmesh, Galvita, Vladimir V., Constales, Denis, Alexopoulos, Konstantinos, Yablonsky, Gregory, and Marin, Guy B.
- Subjects
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OXIDATION of toluene , *CHEMICAL kinetics , *COPPER oxide , *ALUMINUM oxide , *CATALYSTS , *CHEMICAL reduction , *BIOCHEMICAL substrates - Abstract
Total oxidation of toluene over a CuO–CeO 2 /Al 2 O 3 catalyst was studied by means of Temporal Analysis of Products (TAP) at temperatures of 723–873 K in the absence and presence of oxygen (molar toluene:oxygen ratio = 1:9) at degrees of reduction of the catalyst up to 0.42. A single set of kinetic parameters corresponding to the steps of the detailed mechanism can describe the experimental data. A detailed mechanism with oxidation occurring on Ce 3+ sites and reduction on Cu 2+ sites formed the basis of a microkinetic model. The interaction of reactants and products with the catalyst support was taken into account. A distinction was made between O atoms at the surface of the catalytically active phase and those in the bulk. Transport of the latter to the surface was explicitly accounted for in the model. The abstraction of hydrogen atoms leading to the formation of water is the fastest process. The formation of carbon dioxide occurs through three kinetically significant steps. The potentially slowest step in the whole process was found to be the destruction of the aromatic ring. A linear dependency of the activation energies of the processes which include transport of oxygen from the bulk to the catalyst surface, on the degree of reduction of the catalyst was found. Analysis of the dependency of the catalytic behavior on the catalyst descriptors provided information about the optimum catalyst composition and fraction of the active component exposed, which can be used for catalyst optimization. [ABSTRACT FROM AUTHOR] more...
- Published
- 2015
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47. Hydrotalcite derived (Cu, Mn)–Mg–Al metal oxide systems doped with palladium as catalysts for low-temperature methanol incineration.
- Author
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Jabłońska, Magdalena, Chmielarz, Lucjan, Węgrzyn, Agnieszka, Góra-Marek, Kinga, Piwowarska, Zofia, Witkowski, Stefan, Bidzińska, Ewa, Kuśtrowski, Piotr, Wach, Anna, and Majda, Dorota
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- *
METALLIC oxides , *PALLADIUM catalysts , *METHANOL , *INCINERATION , *COPRECIPITATION (Chemistry) - Abstract
Hydrotalcite derived (Cu, Mn)–Mg–Al mixed metal oxides, synthesized by coprecipitation method, were found to be effective catalysts for methanol incineration. Copper and/or manganese oxides deposited on commercial γ-Al 2 O 3 and MgO were used as the reference catalysts. Cu–Mg–Al–O mixed oxide system was found to be the most active catalysts in a series of the hydrotalcite originated metal oxides and supported samples. On the other hand, copper deposited on Al 2 O 3 and MgO supports were significantly less active than the hydrotalcite derived catalysts. Activity of the catalysts was improved by deposition of small amount of palladium (0.5 wt.%). Temperature-programmed surface reaction method (CH 3 OH-TPSR) and in situ Fourier-transform infrared spectroscopy (FT-IR) were employed to study the species formed on the catalyst surface during the process of methanol oxidation. [ABSTRACT FROM AUTHOR] more...
- Published
- 2015
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- View/download PDF
48. Total oxidation of toluene over gold supported on mesoporous ferrisilicates materials.
- Author
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Benais-Hamidi, Faiha, Chérif-Aouali, Leïla, Siffert, Stéphane, Cousin, Renaud, and Bengueddach, Abdelkader
- Subjects
OXIDATION of toluene ,GOLD ,MESOPOROUS materials - Abstract
Mesoporous ferrisilicates MFS-n (n = Si/Fe) with different Si/Fe molar ratio (Si/Fe = 20, 135) were synthesised by the assembly of Fe MFI nanoclusters with triblock copolymers in strongly acidic media. Au/MFS-n catalysts were prepared by deposition-precipitation with urea (DPU) with a loading of gold of 1 wt%. They were characterised by various techniques including XRD, BET, FT-IR spectroscopy; diffuse reflectance UV-vis (DRUV-vis), TPR. Total oxidation of toluene was investigated on MFS-n and Au/MFS-n. The catalytic activity of MFS-n materials for total toluene oxidation is considerably enhanced as the iron content increases. The presence of gold improves the catalytic activity of MFS-n towards the combustion of toluene, the extent of this effect depending on the Si/Fe molar ratio. The catalysts are totally selective for CO
2 and H2 O. [ABSTRACT FROM AUTHOR] more...- Published
- 2015
- Full Text
- View/download PDF
49. Catalytic total oxidation of 1,2-dichloroethane over highly dispersed vanadia supported on CeO2 nanobelts.
- Author
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Dai, Qiguang, Bai, Shuxing, Li, Hua, Liu, Wei, Wang, Xingyi, and Lu, Guanzhong
- Subjects
- *
CATALYTIC oxidation , *ETHYLENE dichloride , *VANADIUM compounds , *CATALYST supports , *CERIUM oxides , *NANOBELTS - Abstract
CeO 2 nanobelts were synthesized via a facile aqueous-phase precipitation route under mild conditions (template-free and non-hydrothermal), and then the highly dispersed vanadia catalysts with a wide range of VO x loadings were prepared by a conventional incipient-wetness impregnation method. The target VO x /CeO 2 catalysts were characterized in detail and used in catalytic combustion of 1,2-dichloroethane (DCE). The results revealed that the monolayer dispersed VO x (6.0%VO x /CeO 2 ) exhibited the most outstanding initial and stable activities, however, the main product containing carbon was CO, not desired CO 2 . A reaction mechanism of DCE total oxidation was proposed based on the study of TPSR and in situ FTIR. The first step of this mechanism was considered to be a dissociative adsorption of C Cl bonds on Lewis acid sites (such as Ce 4+/3+ , V 5+/4+ or Ce 3+ –O 2− –V 5+ ) via Cl abstraction, and then the dissociated DCE can be oxidized directly to CO 2 by surface active oxygen species over pure CeO 2 . Whereas, over VO x /CeO 2 catalysts, the formation of intermediate acetaldehyde was a key step via C H bond activation and hydrogen transfer on VO x species, subsequently, partially oxidized to CO by the lattice oxygen of VO x . [ABSTRACT FROM AUTHOR] more...
- Published
- 2015
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50. Effect of ultrasound irradiation and Ni-loading on properties and performance of CeO2-doped Ni/clinoptilolite nanocatalyst used in polluted air treatment.
- Author
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Yosefi, Leila, Haghighi, Mohammad, Allahyari, Somaiyeh, and Ashferiz, Saeid
- Subjects
- *
CERIUM oxides , *SONOCHEMISTRY , *NICKEL , *CLINOPTILOLITE , *METAL catalysts , *AIR purification - Abstract
In this research nanocatalysts containing 5, 10 and 15wt.% of Ni, dispersed by sonication over CeO2-clinoptilolite composite support were compared toward total oxidation of toluene. Their catalytic performance at different temperatures between 150 and 350 °C was studied based on the oxidative destruction of toluene. The results indicated that the activity of Ni/CeO2-clinoptilolite nanocatalyst for toluene oxidation increased from 33 to 44% at 250 °C by employing sonochemical method in synthesis of catalyst. Meanwhile, the catalytic activity was also improved when Ni content was increased from 5 to 10 and 15 wt.%. With the aid of several characterization techniques like XRD, FESEM, PSD, EDX, BET and FTIR, the correlation between nanocatalyst structure and its activity was addressed. It is indicated that sonochemical method can lift the catalytic activity due to the better dispersion of catalyst active components and also higher surface area. Among sonicated samples, 15 wt.% Ni nanocatalyst showed the highest toluene oxidation due to the better dispersion of catalyst active components and hence to more effective catalytic sites. [ABSTRACT FROM AUTHOR] more...
- Published
- 2015
- Full Text
- View/download PDF
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