Catalytic Activity Of CuO Research Articles

Controlled Preparation of Hydrangea‐like 0.3Zn‐0.15Sn/CuO Catalysts for the Rochow‐Müller Reaction by Microwave‐Assisted Liquid‐Phase Synergistic Impregnation

AbstractIn catalytic reactions, trace amounts of promoters can make up for the low activity of a catalyst and significantly affect the physicochemical properties of the catalyst. Exploring a simple and efficient composite Cu‐based catalyst is essential to the Rochow‐Müller reaction. In this work, monodisperse, a hydrangea‐like 0.3Zn‐0.15Sn/CuO composite catalyst in the Rochow‐Müller reaction. The composite was synthesized via a microwave‐assisted liquid‐phase synergistic impregnation method in which Sn and Zn were used to dope the CuO surface to create strong Si interaction points. A significant increase in the catalytic activity of CuO was observed after Sn and Zn doping, attributed to the rearrangement of charges on the CuO surface and increase in the Cu atom's core electron density. This work provided a novel and efficient method for preparing efficient Cu‐based catalysts for the Rochow‐Müller reaction.

Evaluation of pharmacological and catalytic activity of CuO and Zn doped CuO nanoparticles

CuO and Zn doped CuO nanoparticles (Zn-CuO NPs) with varying concentration i.e., ZnxCu1−xO (where x = 0, 0.5, 1, and 1.5%) have been prepared via microwave assisted method. The spheroid structure of CuO NPs and the nanorod structure of ZnCuO NPs have been determined using High Resolution Scanning Electron Microscopy (HR-SEM) analysis. Elemental analysis has been carried out using Energy Dispersive X-ray Analysis (EDAX). The particle size and surface area of CuO and Zn-CuO NPs have been confirmed by Brunauer–Emmett–Teller (BET) method. The antibacterial studies have been revealed that Zn(1.5%)-CuO NPs exhibited maximum zone of inhibition (19-29 mm) against the tested four bacterial strains. Zn-CuO NPs have been displayed robust action of antibacterial activity with minimum inhibitory concentration (MIC) of 0.09 µM against Campylobacter coli (C. Coli). DPPH and H2O2 radical scavenging assay investigation have been revealed that the significant scavenging activity has showed by Zn(1.5%)-CuO. The in vitro cytotoxicity evaluation of synthesized material against human breast (MCF7) and human lung (A549) cancer cell lines have been demonstrated that Zn(1.5%)-CuO NPs exhibited better cytotoxic activity against MCF7 cell lines (97.5% cell death) than A549 cell lines (90% cell death).

Comparative investigation of oxidative degradation of organic dye in the presence of H2O2 and CuO nanoparticles synthesized by sol–gel method and green synthesis using flower (Matricaria chamomilla) extract

In this study, CuO nanoparticles have been synthesized via a simple sol–gel method and green synthesis using flower (Matricaria chamomilla) extract. XRD analysis of the synthesized CuO nanoparticles clearly indicated a crystalline nature with a monoclinic structure regardless of the method of synthesis, while SEM revealed that the used synthesis methods affected the morphology of the CuO nanoparticles. The oxidative degradation kinetics of the organic dye Methyl Orange (MO) in the presence of the synthesized catalyst CuO and H2O2 has been investigated and compared depending on the dye concentration, reaction time and temperature. The catalytic activity of CuO was studied by measuring the UV–visible spectrum of the MO dye solution treated with CuO and H2O2. It was determined that the MO degradation reaction kinetics followed the pseudo-first-order mechanism. Thermodynamic studies indicated an endothermic nature (∆H# = +73.03 kJ mol–1) and a decrease in randomness at the catalyst CuO/solution interface during the reaction (∆S# = –0.021 kJ mol–1 K–1). At the same conditions, the green synthesized CuO nanoparticles exhibit similar activity properties as CuO synthesized using the sol–gel method. Besides, the green synthesis of CuO nanoparticles is simple and uses a small number of chemicals. The obtained CuO may be a promising catalyst for the oxidative degradation of organics, especially used in medical procedures.

Preparation, Characterization and Catalytic Activity of Copper(II) Oxide Nanoparticles

An environmental benign synthetic route was used for preparation of copper(II) oxide nanoparticles from copper(II) sulphate precursor. Precipitates of copper(II) hydroxide were prepared from CuSO4.5H2O and NaOH. The product was then calcined at 350˚C to get the expected copper(II) oxide nanoparticles. Characterization of prepared sample was carried out by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), FTIR spectroscopy, X-ray powder diffractometry and reflectance measurement. SEM images show that the particle size was less than 100 nm. It is evident from the EDS analysis that the prepared sample was pure and contains only the atoms of Cu and O. XRD pattern confirmed the presence of only CuO in the sample. This result was supported by FTIR spectrum. The prepared CuO was used to study the adsorption and photodegradation of brilliant red (BR) in aqueous medium. The catalytic activity of CuO was investigated and compared with that of commercial CuO.
 Dhaka Univ. J. Sci. 66(1): 9-13, 2018 (January)

Charaterization and Catalytic Activity of CuO and NiO Supported on ZrO<sub>2</sub> for CO Low Temperature Oxidation

ZrO2 support has been prepared by sol-gel and coprecipitation method. CuO and NiO were supported on the supports and they were the activity metals for the catalysts. The CO conversion was tested. The light-off temperature of CO oxidation was 22°C and CO conversion efficiency was up to 50% at 169°C. The prepared catalysts of Cu, Ni supported on ZrO2-A had a high activity for CO oxidation at low temperature.

Effect of the nanoparticle size of supported copper-containing catalysts on their activity in the selective oxidation of CO in an excess of H2

The catalytic properties of systems prepared by the supporting of CuO onto CeO2, ZrO2, and Zr0.5Ce0.5O2 with particle sizes of 15–25 nm (nitrate pyrolysis (p)) and 5–6 nm (microemulsion method (me)) in the reaction of CO oxidation in an excess of H2 were studied. In the latter case, the supports had an almost homogeneous surface and a small number of defects. The catalytic activity of (me) and (p) supports was low and almost the same, whereas the catalytic activity of CuO/(CeO2, ZrO2, and Zr0.5Ce0.5O2)(me) samples was lower than that of CuO/(CeO2 and ZrO2)(p). The maximum CO conversion (∼100% at 125°C) was observed on 5% CuO/CeO2 (p). The CO and CO2 adsorption species on (p) and (me) catalysts were studied by TPD. Differences in the compositions of copper-containing centers on the surfaces of (p) and (me) systems were found using TPR. The nature of the active centers of CO oxidation and the effect of support crystallite size on the catalytic activity were considered.

Catalytic activity of CuO n–La 2O 3/γ-Al 2O 3 for microwave assisted ClO 2 catalytic oxidation of phenol wastewater

In order to develop a catalyst with high activity and stability for microwave assisted ClO 2 catalytic oxidation, we prepared CuO n –La 2O 3/γ-Al 2O 3 by impregnation–deposition method, and determined its properties using BET, XRF, XPS and chemical analysis techniques. The test results show that, better thermal ability of γ-Al 2O 3 and high loading of Cu in the catalyst can be achieved by adding La 2O 3. The microwave assisted ClO 2 catalytic oxidation process with CuO n –La 2O 3/γ-Al 2O 3 used as catalyst was also investigated, and the results show that the catalyst has an excellent catalytic activity in treating synthetic wastewater containing 100 mg/L phenol, and 91.66% of phenol and 50.35% of total organic carbon (TOC) can be removed under the optimum process conditions. Compared with no catalyst process, CuO n –La 2O 3/γ-Al 2O 3 can effectively degrade contaminants in short reaction time and with low oxidant dosage, extensive pH range. The comparison of phenol removal efficiency in the different process indicates that microwave irradiation and catalyst work together to oxidize phenol effectively. It can therefore be concluded from results and discussion that CuO n –La 2O 3/γ-Al 2O 3 is a suitable catalyst in microwave assisted ClO 2 catalytic oxidation process.

The catalytic activity of CuO x/ZrO 2 for the abatement of NO with propene or ammonia in the presence of O 2

Samples CuO x /ZrO 2 (0.1–8.4 Cu atoms nm −2) were prepared by adsorption or impregnation methods. The characterisation of samples by means of XPS, XRD, DRS, ESR, IR and volumetric adsorption of CO, showed copper dispersion up to 2.5 atoms nm −2, and the presence of CuO in samples with higher Cu content. The selective catalytic reduction of NO with propene or ammonia in the presence of excess oxygen, was studied in a flow apparatus with reactant mixtures of various composition (NO : C 3H 6 : O 2 = 0–4000 ppm : 100–2000 ppm : 0–3.5%; and NO : NH 3 : O 2 = 0–700 ppm : 700 ppm : 3.6%). With both propene and ammonia, CuO x /ZrO 2 catalysts containing up to 2.5 Cu atoms nm −2 were active, selective and stable as a function of the time on stream. On all catalysts, with ammonia as reducing agents, up to 523 K, NO conversion equalled NH 3 conversion leading to 100% selectivity. With both propene and ammonia, NO molecules that were converted to N 2 per Cu atom and per second were nearly independent of the Cu content up to 2.5 Cu atoms nm −2.

Selective oxidation of 2-isopropylnaphthalene to 2-isopropylnaphthalenehydroperoxide in a gas–liquid reaction system using CuO+NaOH aq catalyst

The catalytic activities of CuO+NaOH aq and Cu 2O+NaOH aq in the liquid-phase selective oxidation of 2-isopropylnaphthalene (2-IPN) to 2-isopropylnaphthalenehydroperoxide (2-IPNHP) were compared, and the process parameters using CuO+NaOH aq catalyst were investigated. It was found that the atomic ratio of copper to sodium ions of the catalyst system affected the product distribution, a temperature 100°C was favourable for the selective production of 2-IPNHP, and the degree of back-mixing and liquid-phase mass transfer limitation markedly affected the conversion and selectivity. 2-IPNHP (1.254 mol dm −3) was produced from 2-IPN (6.9 mol dm −3) with 76% selectivity in a bubble column reactor with molecular oxygen as the oxidizing gas. An oxidation mechanism that depends on the unique combined catalytic behaviour of CuO+NaOH aq was proposed.