Copper Impregnation Research Articles

The effect of copper content on the reactivity of Cu/Co6Al2 solids in the catalytic steam reforming of methane reaction

Abstract The steam reforming of methane over Cu/Co6Al2 mixed oxides with different copper contents was studied. The Co6Al2 support was prepared via the hydrotalcite route. It was thermally stabilized at 500 °C, impregnated with 5 wt.%, 15 wt.% or 25 wt.% copper using copper (II) nitrate Cu(NO3)2·3H2O precursor and then calcined again at 500 °C under an air flow. The impregnation of copper enhanced significantly the reactivity of the solids in the considered reaction. The 5Cu/Co6Al2 solid was the most reactive one, with a methane conversion of 96% at 650 °C. The selectivities of H2 and CO2 were also better for the catalyst containing 5 wt.% copper compared to higher copper loadings. The decrease in the catalytic reactivity with increasing the copper content was attributed to the formation of agglomerated and less reactive CuO species, which were detected by XRD and TPR analyses.

Neurodegenerative Changes in Rat Produced by Lithium Treatment

Lithium is extensively used in psychiatric practice for the prevention and treatment of manic-depressive disorders. However, neurotoxicity attributed to lithium salts within therapeutic doses was also reported in patients, manifested by transient or persistent neurological deficits. In this study, morphological changes were examined in rats treated acutely and chronically with lithium. Pathological changes were observed in different brain regions including cerebral cortex, cerebellum, medulla oblongata, mesencephalon, thalamus, and pons, using a silver–copper impregnation technique for neurodegeneration. Vacuolization of brain tissue with subsequent formation of spongiosis was the prominent morphological feature following lithium administration. The zones of spongiosis were irregularly distributed throughout the brain. More intensive compact areas with spongiform changes were found in the cerebral cortex and medulla oblongata. Less pronounced vacuolization was noted in the pons and thalamic region. The cerebellum and mesencephalon appeared least affected. Vacuolization in the cerebellar cortex was found at loci with Purkinje cells, but the classical picture of spongiosis was not apparent. Data indicate that both acute and chronic lithium intoxication accelerated neurodegenerative changes normally seen with normal brain aging.

Copper impregnated ionic liquid assisted mesoporous titania: visible light photocatalyst

Mesoporous titania (Ms-TiO2) is successfully prepared using water immiscible room-temperature ionic liquid 1-butyl-3-methyl-imidazolium-tetrafluoroborate as a template and an effective additional solvent via the sol–gel method at low temperature. Ms-TiO2 is designed as an efficient visible light photocatalyst by copper (Cu) impregnation. X-ray diffraction analysis presents the nanocrystalline anatase phase. Cu impregnated Ms-TiO2 (Cu/Ms-TiO2) samples extend the absorption edge to the visible region. The X-ray photoelectron spectrum indicates the mixed valence states of Cu as Cu+ and Cu2+. The beneficial effect of Cu can be explained by the formation of oxygen vacancies with more Cu+ state. Cu/Ms-TiO2 samples exhibit superior visible light photocatalytic activities to Ms-TiO2, P-25 and 2.0% Cu/P-25 in the case of 2,4-dichlorophenol and methyl orange. Efficient charge separation due to the formation of Ti–O–Cu bonding at the surface and the associated appearance of oxygen vacancies together form the reason for higher degradation rate of organic compounds under illumination.

Catalytic efficiency of copper oxide in degradation of phenol using sintered calcium phosphate (SCaP) as catalyst support

For the first time sintered calcium phosphate is explored as catalyst–support, analogous to silica, alumina etc. The present work involves preparation of catalysts by depositing copper oxide over the sintered calcium phosphate using three techniques, viz., impregnation of CuO, impregnation of copper (II) nitrate & calcination, reduction of Cu 2 + ions on the support & calcination. The above samples were characterized using XRD, UV-DRS, SEM-EDAX, BET surface area and acidity. Oxidation of phenol was studied with the above catalysts and sintered calcium phosphate was found to be an efficient catalyst–support. ► Sintered calcium phosphate (SCaP) used as the catalyst–support for the first time. ► Fine particles of CuO were deposited over SCaP using DRC technique. ► Phenol degradation of 95% at room temperature was achieved within 90 min of reaction time. ► Induction period was as low as 10 min of reaction time.

Preferential oxidation of CO in excess H2 over CuO/CeO2 catalysts: Characterization and performance as a function of the exposed face present in the CeO2 support

A series of oxidised copper-cerium nanostructured catalysts prepared by impregnation of copper over ceria supports synthesized by different methods (hydrothermal with varying preparation parameters, microemulsion/precipitation), in order to achieve different specific morphologies (nanocubes, nanorods and nanospheres), have been examined with respect to their catalytic properties for preferential oxidation of CO in excess H2 (CO-PROX). The catalysts have been characterized in detail by XRD, Raman, SBET measurement, HREM, XPS, TPR and EPR, which allows establishing a model of structural characteristics of the catalysts. The characterization results have been correlated with analysis of CO-PROX catalytic properties by means of catalytic activity measurements complemented by operando-DRIFTS. Structural dependence of the CO oxidation reaction on the dispersed copper oxide entities as a function of the exposed face present at the surface of the different ceria supports is revealed. An important overall enhancement of the CO-PROX performance is detected for the sample supported on ceria nanocubes which is proposed to be a consequence of the interaction between copper oxide and (100) faces of the ceria support.

Effect of ultrasound on the structural and textural properties of copper-impregnated cerium-modified zirconium-pillared bentonite

In this study, the synthesis of zirconium-pillared bentonite modified with cerium was performed via two different methods by the application of conventional and ultrasonic treatments during the intercalation stage. To synthesise copper-impregnated pillared clays by wet impregnation, cerium-modified zirconium-pillared clays were used as supportive materials after being calcined at 300 °C. Ultrasonic treatment significantly decreased the required processing time compared with the conventional treatment of the synthesised pillared bentonites. Chemical analysis confirmed the incorporation of Zr 4+, Ce 4+ and Cu 2+ species into the pillared bentonites. X-ray diffraction (XRD) patterns of zirconium- and cerium/zirconium-pillared bentonites prepared by conventional treatment show that one large d-spacing above 3.5 nm corresponds to the mesoporous delaminated part, and another small d-spacing above 1.7 nm is indicative of the microporous pillared part. Zirconium- and cerium/zirconium-pillared bentonites prepared via ultrasonic treatment exhibited similar results, with the same high d-spacing but with a second low-intensity d-spacing above 1.9 nm. The delaminated structures of the pillared bentonites synthesised by both methods were conserved after copper impregnation. Nitrogen-adsorption isotherm analysis showed that the textural characteristics of products synthesised by ultrasonic treatment were comparable to those of products synthesised by conventional treatment. Fourier-transform infrared spectroscopy (FTIR) analyses showed the presence of Brønsted- and Lewis-acid sites, and zirconium-pillared clays synthesised by conventional treatment exhibited increased numbers of Brønsted- and Lewis-acid sites after cerium addition and copper impregnation. However, the products synthesised by ultrasonic treatment exhibited an increased number of Brønsted- and Lewis-acid sites after cerium addition, but a decreased number of acid sites after copper impregnation.

The Performance of the Cu-Zn/CeO<sub>2</sub> Catalysts in the Steam Reforming of Methanol Reaction

The performances of different xCu10Ce and xZn10Ce (x = 1, 3, and 5) catalysts prepared by impregnation method then pelletised, were investigated in the steam reforming of methanol (SRM) under a GHSV = 15500 h-1 with H2O/CH3OH = 2. The impregnation of copper over ceria supports shows better results than that of zinc. The catalytic activity in the Cu-based depends on the dispersion of the copper species. The methanol conversion rate is related to the formation of an optimum content of reduced copper species.

Dual role of copper on the reactivity of activated carbons from coal and lignocellulosic precursors

The synthesis of copper-doped activated carbons from different origin (i.e., lignocellulosic and bituminous coal) by a wet impregnation and low temperature calcination procedure has been explored, as well as the role of copper particles on the physicochemical and structural features of the resulting materials. The textural characterization and isothermal reactivity analysis of the pristine and doped activated carbons have shown that the role of copper during the calcination step strongly depended on the nature of the carbon matrix. Copper impregnation of a coal-derived activated carbon catalyzed the air gasification of the material at a very low temperature (i.e., 325°C), bringing about the development of microporosity on the doped carbon. In contrast, when copper was immobilized on a lignocellulose-derived activated carbon, the metallic species act as combustion retardant during the calcination step, protecting the carbon matrix during the catalytic gasification. In both cases, the resulting materials displayed a homogenous distribution of copper within the carbon matrix, while preserving large textural properties.

Cu/Zn-based catalysts for H 2 production via steam reforming of methanol

The performances of different xCu10Al, xZn10Al ( x = 1, 3, and 5), 5%Zn5Cu10Al and 5%Cu5Zn10Al catalysts prepared by impregnation method then pelletised, were investigated in the steam reforming of methanol (SRM) at 350 °C under a gas hourly space vilosity of 15,500 h −1 with steamed water and methanol mixture (H 2O/CH 3OH = 2). The impregnation of copper over alumina supports shows better results than that of zinc. Concerning copper based catalysts, the gas selectivity was found to be strongly dependent on the reduction state of the copper and its dispersion over the support. The presence of zinc over Alumina seems to favor the reverse water gas shift reaction. Among all the tested series, the 5%Cu5Zn10Al shows the highest performance due to the presence of ZnAl 2O 4 spinal form that stabilises the Cu +, which is the most active specie in the SRM.

A facile method for the synthesis of copper modified amine-functionalized mesoporous zirconia and its catalytic evaluation in C–S coupling reaction

A new copper modified amine functionalized zirconia has been synthesized by a co-condensation method using zirconium butoxide and aminopropyltriethoxy-silane (APTES) in the presence of a cationic surfactant CTAB followed by impregnation of copper. Nitrogen adsorption-desorption, X-ray powder diffraction, Fourier-transform infrared spectroscopy (FT-IR), (13)C nuclear magnetic resonance (NMR), scanning electron micrography (SEM), transmittance electron micrography (TEM), thermo gravimetric analysis-differential thermal analysis (TGA-DTA), X-ray photoelectron spectroscopy (XPS) and UV-vis DRS spectroscopic tools are used to characterize the materials. FT-IR and DRS results indicated the incorporation of Cu and amino groups on the surface of zirconia. This Cu-anchored mesoporous material acts as an efficient, reusable catalyst in the aryl-sulfur coupling reaction between aryl iodide and thiophenol for the synthesis of value added diarylsulfides.

Operando DRIFTS and XANES Study of Deactivating Effect of CO2on a Ce0.8Cu0.2O2CO-PROX Catalyst

Deactivating effects produced by CO2 on a catalyst combining oxidized copper and cerium prepared by microemulsion−coprecipitation and employed for preferential oxidation of CO in a H2-rich stream have been examined by means of operando-DRIFTS and -XANES (Cu K and Ce L3 edges) spectroscopies. The results reveal that CO oxidation activity is basically affected by CO2-induced hindrance of redox activity at the interface between dispersed copper oxide particles and the support as a consequence of carbonate formation. This appears influenced by support acid−base properties, as revealed by comparison of the obtained results with those observed over a different catalyst that was prepared by copper impregnation on pure ceria. CO2 is shown to affect negatively H2 oxidation activity, too, which is related to prevention of the extension of the reduction from the interface to the rest of the dispersed copper oxide particles, a process that provides active sites for such reaction.

Electrochemical in situ impregnation of wood using a copper nail as source for copper

A new method for copper impregnation of wood in structures was suggested and tested in laboratory scale with specimen of new pine sapwood. A copper nail and a steel screw were placed in the wood, and an electric direct current field was applied, so the copper nail was anode and the screw was cathode. At the anode, copper ions were generated. The copper ions were transported into the wood by electromigration (movement of ions in an applied electric field) towards the cathode, and a volume between the two electrodes was thereby impregnated. Copper also moved to a lesser degree in the opposite direction, probably due to capillary effects, and a smaller volume behind the anode was impregnated as well. The impregnation perpendicular to the grain was limited compared to the one along the grain. The highest Cu concentrations were obtained close to the anode.

Gas-phase hydrogenation of propionitrile on copper-lanthanide oxides

The hydrogenation of propionitrile on copper-lanthanide oxide catalysts (2Cu·CeO 2 and 4Cu·Ln 2O 3 (Ln = La, Pr, Nd)) was studied in the gas phase. The activity of the catalysts varies with the lanthanide in the order 2Cu·CeO 2 > 4Cu·Pr 2O 3 > 4Cu·La 2O 3 ≥ 4Cu·Nd 2O 3, while the activation energies varies in the opposite order, except for 2Cu·CeO 2. The main product was the primary amine, n-propylamine. The formation of the unstable imine CH 3CH 2N CHCH 3 as a major product over 2Cu·CeO 2 seems to be consistent with the acidity of the catalyst. The catalysts were more selective than conventional copper impregnation catalysts, Cu (10 wt.%) on SiO 2, La 2O 3 or CeO 2, that produce significant quantities of the secondary amine.

Synthesis and Activity Comparison of Copper-Incorporated MCM-41-Type Sorbents Prepared by One-Pot and Impregnation Procedures for H2S Removal

In the present study, novel copper-incorporated MCM-41-type high-surface-area mesoporous materials were synthesized following a direct hydrothermal synthesis method and also by the impregnation of copper into the mesopores of the pre-synthesized MCM-41 structure. XRD results indicated the formation of a CuO phase within the MCM-41 structure. Sharp H2S breakthrough curves, quite high sorption rate parameters, and high sulfur retention capacities were obtained in high-temperature removal of H2S using these copper-incorporated mesoporous materials. XRD patterns of the sulfided products indicated the formation of a Cu1.81S phase within the MCM-41 structure. A deactivation model gave good predictions of the experimental H2S breakthrough data.

Physico-chemical study of impregnated Cu and V species on CeO2 support by thermal analysis, XRD, EPR, 51V-MAS-NMR and XPS

CuVCe oxides were prepared by impregnation of copper and/or vanadium precursors on ceria support. The solids freshly prepared were calcined under air between 400 and 700 °C. Physico-chemical properties of these oxides were then studied using different techniques: Thermal Analysis (DSC/TG), X Ray Diffraction (XRD), Electron Paramagnetic Resonance (EPR), 51V Magic Angle Spinning Nuclear Magnetic Resonance (51V-MAS-NMR) and X-Ray Photoelectron Spectroscopy (XPS). X-ray diffraction and thermal analysis revealed cerium orthovanadate phase formation during the calcination of the 1Cu1V10Ce solid. This CeVO4 phase is not observed for the 10Cu1V10Ce sample. The EPR study revealed two well-resolved copper signals: the first corresponds to isolated Cu2+ species and the second to Cu2+ dimers. The 51V-MAS-NMR confirmed the presence of CeVO4 phase for 1Cu1V10Ce sample and revealed polymeric V–O–V chains in interaction with a copper ceria matrix for 10Cu1V10Ce sample. Finally, the XPS study indicated high vanadium content on the solid surface. This phenomenon is enhanced by the copper content in the solid and could explain the absence of the CeVO4 phase in 10Cu1V10Ce sample. Thus the ceria orthovanadate phase formation is inhibited by the presence of a high copper content in the solid.

Investigation of the Cu–Zr–Y oxides activity in the carbon black catalytic oxidation by differential thermal analysis and temperature programmed reduction

Different copper/zirconium-yttrium catalysts have been tested in carbon black oxidation reaction. Supported mainly on differential thermal analysis and temperature programmed reduction, two different mechanisms have been proposed to explain the catalytic results. In the absence of copper, it has been shown that Zr 3+ ions and associated anionic vacancies are responsible to the catalytic enhancement observed in the mixed oxides, oxygen species being activated on these sites. Among mixed zirconia–yttria solids, ZrO 2-5 mol%Y 2O 3 is the most active catalyst. Copper impregnation on these oxides leads to the formation of different copper species. Small particles of CuO in low interaction with the support, induce a catalytic improvement due to the highest reducibility of these species. Moreover, in order to be more efficient, CuO species should have some interactions with the support, since impregnated samples are more active than the simple mechanical mixtures.

Synthese et caractérisation de catalyseurs a base de cuivre: application a la réaction d'oxydation du phénol

Abstract Synthesis and characterization of copper catalysts: application to the oxidation of phenol. The catalytic oxidatin of organic pollution has already been treated several publications reporting the use of ozone, air or hydrogen peroxide as oxidants. These systems require very severe conditions of temperature and pressure. It was thus useful to develop active, stable and inexpensive oxidizing systems. For this purpose we prepared catalysts by impregnation of copper on a natural clay; these catalysts were characterized, then used in the reaction of oxidation of phenol in the presence of hydrogen peroxide, at atmospheric temperature and pressure. The results showed a very significant activation of hydrogen peroxide by the catalyst, the phenol depletion percentage reaching 65 % after 4 h, and very significant stability of the catalyst.

Chromium ― Copper System: Adhesion Characteristics, Doping, the Structure of Phase Boundary and Composites

The adhesive characteristics and the formation of phase boundaries in the Cr ― Cu system in a vacuum of (2-4)·10−3 Pa in the temperature range 1100-1300°C have been studied. The microstructure of composites (50:50 by mass) made by copper impregnation of porous samples of Cr electrolytic powders and Cr obtained by calcium hydride reduction. The effect of Cr, Fe, Co, Ni, Si additions on above characteristics has been investigated.

Development of a new epoxy resin for superconducting magnet impregnation

A novel epoxy resin system based on a low viscosity Bisphenol-A (DGEBA)/Bisphenol-F (DGEBF) blend has been investigated for use in tight-wound superconducting magnet impregnation. The principle is to decrease the Bisphenol-A resin system viscosity by adding the low viscosity Bisphenol-F resin. The rheological and mechanical properties of the blend system are compared to the pure Bisphenol-A resin and also to the Bisphenol-F resin both cured with acid anhydride. For the vacuum/pressure impregnation, both the pure Bisphenol-F resin system and DGEBA/DGEBF blend system can be applied without S-glass fabric between coil layers due to its higher rigidity at low temperature and good resistance to thermal shock. This resin system have been tested for impregnation of copper and NbTi wire wound coils whilst Bisphenol-A resin system have been used for testing Nb/sub 3/Sn coil impregnation where S-glass braid is present as wire insulation.

Modification of tribological properties of polyarylate by supercritical fluid impregnation of copper(II) hexafluoroacetylacetonate

Polyarylate has been used as a model polymer to study its tribological property alteration during impregnation of copper(II) hexafluoroacetylacetonate in a supercritical carbon dioxide environment followed by thermal decomposition of the copper compound in air. The initial, impregnated and thermally treated polymer samples were tested by various tribological techniques to compare their wear resistance, friction coefficient fk and surface microhardness H. SEM, EDX and ESCA have been applied to determine surface and internal domain morphology, profiles of copper complex concentration, its types and influence on the tribological properties of the samples. Dramatic surface layer modification and significant enhancement of its wear resistance (more than 400%) due to this process have been observed and discussed.