Search results for "Oxides"
showing 10 items of 547 documents
Characterization of hydroxyaromatic compounds in vegetable oils by capillary electrophoresis with direct injection in an oil-miscible KOH/propanol/me…
2005
The separation of hydroxyaromatic compounds in vegetable oils, including synthetic antioxidants (3-tert-butyl-4-hydroxyanisol and 2,6-di-tert-butyl-4-hydroxytoluene), E-vitamers and other natural oil components, by nonaqueous capillary electrophoresis in an oil-miscible background electrolyte (BGE) was investigated. The BGE contained 40 mM KOH in a methanol/1-propanol (PrOH) mixture (15:85 v/v). The oil samples were 1:1 diluted with PrOH and directly injected in the capillary. Under negative polarity (cathode at the injection end), the anionic solutes moved faster than the electroosmotic flow, being well-resolved among them and from the triacylglycerols. Using virgin palm, extra virgin oliv…
Functionalized poly(butylene succinate) by nitroxide radical coupling
2014
In recent years there has been a growing interest in developing sustainable alternatives to oil-based plastics. In particular, biodegradable aliphatic polyesters, such as poly(lactic acid) (PLA) and poly(butylene succinate) (PBS), are becoming increasingly important due to their valuable properties including thermoplastic processability and thermo-mechanical properties. Nonetheless, these materials present several drawbacks, such as the lack of reactive functionalities that are limiting their applications, versatility and successful use as commodity plastics. In this work it was investigated for the first time a new method of preparation of functionalized PBS by a post-polymerization approa…
INTERACTIONS BETWEEN FUNCTIONALIZED THERMOPLASTIC ELASTOMER AND LAYERED DOUBLE HYDROXIDES
2016
Results coming from rheological analysis clearly suggest that in SEBS-g-MA-based nanocomposites, containing high amount of o-LDH, the formation of strong interactions between the dispersed nanoparticles and maleic functionalities of matrix occurs. A significant modification of the rheological behaviour can be noticed due to the formation of gel-like structures.
Reduction and catalytic behaviour of heterobimetallic copper–lanthanide oxides
2008
Abstract The reduction of the heterobimetallic copper–lanthanide oxides 2CuO·CeO2 and 3CuO·Ln2CuO4 (Ln = La, Pr, Nd) was studied by H2-TG/DTA and H2-TPR. All systems exhibit two main reduction steps accompanied by mass losses in the temperature range 20–1000 °C. The first step was attributed to CuO reduction, whereas the second step is due either to copper reduction in the Ln2CuO4 phase with the concomitant formation of Ln2O3 or to the surface reduction of CeO2. The products were characterized by XRD, SEM, EDX, and BET techniques and are better described as supported copper type materials. They were active for the mesityl oxide (4-methyl-2-penten-2-one) gas phase hydrogenation.
Ecofriendly Biopolymer-Based Nanocomposite Films with Improved Photo-Oxidative Resistance
2022
The interest towards high performance biopolymer-based materials increases continuously and, to guarantee appropriately industrial applications, the photo-oxidative resistance and stability of these materials must be adequately addressed. In this study, innovative biopolymer-based nanocomposites, i.e., Polyamide 11 (PA11), containing ad-hoc modified Layered Double Hydroxides (LDH), were successfully formulated and characterized. Particularly, LDH were considered carriers for hindered amine light stabilizing molecules, so two different hindered amine moieties (HALS1 and HALS2) were anchored on LDH layered internal structures and/or outer surfaces. The presence of HALS1 and HALS2 in LDH were …
Monitoring Chemical Reactions with SERS-Active Ag-Loaded Mesoporous TiO2 Films
2020
Monitoring chemical reactions that occur in small spaces or confined environments is challenging. Surface-enhanced Raman scattering (SERS) spectroscopy offers the unique possibility to monitor spectral changes with high sensitivity and time resolution. Herein, we report the application of composite mesoporous TiO2 films loaded with Ag nanoparticles (NPs) to track in situ chemical processes in real time. In particular, the AgNPs@TiO2 system was employed to monitor two chemical reactions: one occurring on the Ag NPs surface and another taking place in the surrounding solution. In the first case, we monitored the decarboxylation reaction of 4-mercaptobenzoic acid on Ag NPs, which allowed us to…
NOx selective catalytic reduction at high temperatures with mixed oxides derived from layered double hydroxides
2012
[EN] Mixed oxides derived from layered double hydroxides (LDHs) have been investigated as potential catalysts for the NOx removal at high temperatures. The best results were obtained with Co–Al mixed oxides derived from LDHs that are active at 750 ◦C in the presence of oxygen and water. These catalysts could reduce or/and decompose the NOx formed in the dense phase of the FCC regenerator, being deactivated at oxygen concentrations higher than 1.5%. Nevertheless this deactivation is not permanent and they would be regenerated after reduction with hydrogen at 530 ◦C. The influence of the layered double hydroxides (LDHs) preparation method on the catalyst activity was studied, observing that t…
Micro-Raman study of red decorations in French faiences of the 18th and 19th centuries
2006
Obtaining the red color was a technical and economic challenge for the French faience manufactories in the 18th and 19th centuries. The tendency of the red hematite to turn into drab brown during the firing process explains the difficulty in obtaining this color. Red decorations in shards coming from the four production centers of faience manufacturing during this period—Rouen (northwest), Nevers (central), Thiviers (southwest) and Argonne (northeast)—have been studied by means of micro-Raman spectroscopy, scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX). Among them, Thiviers appears to be the leader thanks to a particular reddish sandstone called ‘Gres de T…
Effect of different co-solvents on biodiesel production from various low-cost feedstocks using Sr–Al double oxides
2020
The main objective of the present paper comprises the investigation of biodiesel production from low-cost feedstock such as lard oil and waste cooking oil (WCO) using Sr-Al double oxides. Nanocatalyst was characterised FTIR, XRD, SEM, TEM, BET and XPS. The Sr:Al with 3:1 molar ratio showed the best catalytic activity in the conversion of both oils to fatty acid methyl ester. The effect of acetone and tetrahydrofuran (THF) as a co-solvent for transesterification were compared and the best result was obtained with 5 % THF. The mutual effect of the nanocatalyst and co-solvent on biodiesel production was investigated. The characterisation of biodiesel synthesised from lard oil and WCO was perfo…
DFT Prediction of Enhanced Reducibility of Monoclinic Zirconia upon Rhodium Deposition
2018
Oxides are an important class of materials and are widely used, for example, as supports in heterogeneous catalysis. In a number of industrial catalytic processes, oxide supports actively participate in chemical transformations by releasing lattice oxygen anions. While this is intuitively understood for reducible oxides, the reducibility of irreducible oxides may be modified via nanoengineering or upon inclusion of foreign species. Our calculations predict that the ability of irreducible monoclinic zirconia to release oxygen improves substantially upon deposition of rhodium. Through a comprehensive screening of Rh/ZrO2 with different size of the rhodium species, we find that a Rh adatom and…