Search

Copper oxide nanoparticles incorporated-zeolite supported-graphitic carbon nitride (CuO/g–C3N4/Zeolite Y) catalyst was fabricated through a facile hydrothermal method, in which CuO nanoparticles were produced via precipitation. The synthesized CuO/g–C3N4/Zeolite Y was examined using characterization techniques such as FT-IR, XRD, XPS, TEM, SEM, EDX, TG, BET, DRS, and PL. BET analysis revealed that integrating zeolite and CuO has increased the surface area of graphitic carbon nitride. Increased separation efficiency and reduced recombination rates of photogenerated electrons and holes in CuO/g–C3N4/Zeolite Y were confirmed by photoluminescence studies. The CuO/g–C3N4/Zeolite Y catalyst exhibits enhanced efficiency for degrading MB and CV dyes compared to pristine g-C3N4 under sunlight exposure. The active species studies demonstrated that hydroxyl radicals, superoxide anion radicals and holes involve in the photocatalytic destruction of pollutants. Additionally, the CuO/g–C3N4/Zeolite Y composite efficiently degraded the antibiotic ceftazidime. Intermediates generated during the degradation process were identified, and plausible degradation pathways for ceftazidime were proposed through LC–MS analysis. This study implies that the synthesized catalyst can be used in the wastewater cleanup process to eliminate persistent organic contaminants and pharmaceutical pollutants under sunlight irradiation. [ABSTRACT FROM AUTHOR]

CuO@TiO2 core–shell nanostructure catalyst with CuO core and TiO2 shell was prepared by a two-step method and then used in NH3-SCR reaction. FE-SEM, TEM and element mapping were used to investigate the morphologies of the sample. Their results indicated CuO nanorods were coated with TiO2 and thus forming a core–shell nanostructure. According to the results of N2 adsorption–desorption, XRD, Raman, XPS, NH3-TPD, H2-TPR and in situ DRIFTS, the core–shell nanostructure would benefit the formation of better redox ability, more oxygen vacancies, more acid sites and abundant adsorbed NOx species on the catalyst. Thus, the core–shell nanostructure catalyst presented significantly higher activity than pure CuO and TiO2. NH3-SCR reaction on CuO@TiO2 core–shell catalyst should follow both Eley–Rideal (E-R) mechanism and Langmuir-Hinshewood (L–H) mechanism. These findings may promote the development of the new effective non-vanadium-based SCR catalysts. [ABSTRACT FROM AUTHOR]

CuO@TiO2 core–shell nanostructure catalyst with CuO core and TiO2 shell was prepared by a two-step method and then used in NH3-SCR reaction. FE-SEM, TEM and element mapping were used to investigate the morphologies of the sample. Their results indicated CuO nanorods were coated with TiO2 and thus forming a core–shell nanostructure. According to the results of N2 adsorption–desorption, XRD, Raman, XPS, NH3-TPD, H2-TPR and in situ DRIFTS, the core–shell nanostructure would benefit the formation of better redox ability, more oxygen vacancies, more acid sites and abundant adsorbed NOx species on the catalyst. Thus, the core–shell nanostructure catalyst presented significantly higher activity than pure CuO and TiO2. NH3-SCR reaction on CuO@TiO2 core–shell catalyst should follow both Eley–Rideal (E-R) mechanism and Langmuir-Hinshewood (L–H) mechanism. These findings may promote the development of the new effective non-vanadium-based SCR catalysts. [ABSTRACT FROM AUTHOR]

Catalytic transformation of nitroaromatic compounds in wastewater using nanostructured catalysts is a promising method for wastewater treatment. Here, we report a systematic study on morphology-dependent catalytic activity of CuO nanostructures for efficient reduction of 4-nitrophenol (4-NP) in water. The morphology of CuO nanostructures was controllably varied from nanorods, nanosheets and hierarchical 3D flower-like structures by simply varying ammonia concentration in a simple wet chemical approach. Catalytic transformation of toxic 4-NP into useful 4-aminophenol by the prepared nanostructured CuO samples were investigated. The impact of morphology on the catalytic activity of nanostructured CuO catalysts was examined. It was observed that hierarchical 3D flower-like CuO catalysts show enhanced catalytic activity as compared to nanorods and nanosheets. The origin of this morphology-dependent catalytic activity of CuO nanostructures is discussed. [ABSTRACT FROM AUTHOR]

Cabbage-type morphology of cupric oxide (CuO) and cuprous oxide (Cu2O) nanostructures were synthesized via a simple and cost-effective chemical approach. HRTEM, FESEM, XRD, UV–Vis absorption and photoluminescence spectroscopies were used to identify the structural, optical, morphological and catalytic properties of the prepared nanostructures. Phase of the prepared copper oxide nanostructures was well controlled by changing the concentration of glucose. The prepared cabbage-type Cu2O nanostructures showed exceptionally improved catalytic performance towards the reduction of toxic 4-nitrophenol into useful 4-aminophenol as compared to cabbage-type CuO nanostructures. Cabbage-type Cu2O nanostructures completely transformed 4-NP into 4-AP in just 5 min with excellent rate constant (0.587 min−1). The observed excellent catalytic activity of prepared cabbage-type Cu2O nanostructures indicates their potential use in catalytic applications. [ABSTRACT FROM AUTHOR]

CuO loaded on siliceous MCM-48 (Mobil Composition of Matter No.48) containing spatially isolated titania species were prepared in this study. X-ray diffraction, N-physisorption, high resolution transmission electron microscopy, X-ray photoelectron spectroscopy and diffuse reflectance spectroscopy were used to characterize these samples. Results from characterizations showed that the addition of CuO to Ti-MCM-48 could markedly improve the photocatalytic degradation properties of organic pollutions such as rhodamine B and tetracycline hydrochloride under solar-simulated irradiation. The enhanced photocatalytic performance of CuO/Ti-MCM-48 may be due to the formation of p-n heterojunctions between CuO and Ti-MCM-48, resulting in the effective separation of photogenerated electron-hole pairs and the enhanced absorption of visible light. According to the trapping experiment, a possible photocatalytic mechanism of CuO/Ti-MCM-48 composite for the degradation of organic pollutions was proposed. Graphical Abstract: The p-n hetero junctions between Ti-MCM-48 and CuO suppress the photogenerated electron-hole recombination and enhance absorption of visible light, thus improving the photocatalytic degradation of organic pollutions. [ABSTRACT FROM AUTHOR]

Different types of copper oxide in CuO-CeO/AlO were investigated structurally and catalytically. Standard preparation lead to the presence of CuO monocrystals and CeCuO as evidenced by XRD, HRTEM and EDX. Washing with nitric acid removed the monocrystals, while leaving the CeCuO solid solution. The Fourier transformed Cu K patterns for the HNO-washed catalyst showed a diminished second Cu shell, characteristic for CeCuO as well as for X-ray amorphous nano-sized CuAlO spinel phase. XANES analysis and first shell Cu fitting confirmed this CuAlO like structure outside CeCuO. By modeling the Ce K EXAFS signal in the washed sample, the amount of Cu in CeCuO was determined to be 18 ± 6 %. Total oxidation of CO and CH as model reactions showed little difference in activity between non-washed and washed CuO-CeO/AlO, indicating that CuO monocrystals were hardly active at temperatures below 450 °C. XRD performed in situ during TPR and TPO showed that CeO in CeCuO added to the redox capacity of both CuO-CeO/AlO samples as it was partially reduced at 300 °C. At higher temperatures, the CuO monocrystals also participated in reaction, leading to a higher activity for the oxidation of CH. Graphical Abstract: [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

This work describes a new technique, sol-pyrolysis method, for depositing CuO–CeO2on FeCrAl honeycomb supports. The monolithic catalysts prepared by the method presented good adhesion stability in ultrasonic and thermal shock tests. The principle of the deposition and the role of the support were studied and analyzed by SEM, XRD, TG-DTA, TPR and XPS techniques. The results showed that the active components adhered to the support via three stages. High surface energy of the crystal nuclei and the interaction between the active components and the support promoted adhesion stability. Moreover, the presence of the support influenced distribution and interaction of the active components, but had no obvious effect on catalytic performance. The CuO–CeO2/Al2O3/FeCrAl monolithic catalysts were applied for the preferential oxidation of carbon monoxide in rich-hydrogen gases and revealed high activity and good selectivity under the presence of 15%CO2 and 10%H2O. [ABSTRACT FROM AUTHOR]

The oxidative dehydrogenation of propane on CuO has been investigated at 723 K in the presence and absence of tetrachloromethane (TCM). Under oxygen-limiting conditions, the conversion of propane and the selectivity to propylene were enhanced by the introduction of TCM. The catalyst converted to metallic Cu during the oxidation in the absence of TCM while no conversion of CuO was observed in the sample used in the presence of TCM. In contrast, the conversion of propane dramatically decreased upon addition of TCM into the feedstream for the oxidation of propane under the oxygen-excess conditions. The catalyst used under the oxygen-excess conditions was not reduced to metallic Cu, regardless of the addition of TCM. It is suggested that an abstraction of lattice oxygen from the catalyst is strongly influenced by the concentration of oxygen in the feed, resulting in the different effect of TCM on the oxidative dehydrogenation of propane. [ABSTRACT FROM AUTHOR]

X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) have been used to characterize a series of Cu/Ce/Al2O3 catalysts. Catalysts were prepared by incipient wetness impregnation using metal nitrate and alkoxide precursors. Catalyst loadings were held constant at 12 wt% CuO and 5.1 wt% CeO2. Mixed oxide catalysts were prepared by impregnation of cerium first, followed by copper. The information obtained from surface and bulk characterization has been correlated with CO and CH4 oxidation activity of the catalysts. Cu/Al2O3 catalysts prepared using Cu(II) nitrate (CuN) and Cu(II) ethoxide (CuA) precursors consist of a mixture of copper surface phase and crystalline CuO. The CuA catalyst shows higher dispersion, less crystalline CuO phase, and lower oxidation activity for CO and CH4 than the CuN catalyst. For Cu/Ce/Al2O3 catalysts, Ce has little effect on the dispersion and crystallinity of the copper species. However, Cu impregnation decreases the Ce dispersion and increases the amount of crystalline CeO2 present in the catalysts, particularly in Ce modified alumina prepared using cerium alkoxide precursor (CeA). Cerium addition dramatically increases the CO oxidation activity, however, it has little effect on CH4 oxidation. [ABSTRACT FROM AUTHOR]