Application of CuxO-FeyOz Nanocatalysts in Ethynylation of Formaldehyde

Abstract

Composite nanomaterials have been widely used in catalysis because of their attractive properties and various functions. Among them, the preparation of composite nanomaterials by redox has attracted much attention. In this work, pure Cu2O was prepared by liquid phase reduction with Cu(NO3)2 as the copper source, NaOH as a precipitator, and sodium ascorbate as the reductant. With Fe(NO3)3 as the iron source and solid-state phase reaction between Fe3+ and Cu2O, CuxO-FeyOz nanocatalysts with different Fe/Cu ratios were prepared. The effects of the Fe/Cu ratio on the structure of CuxO-FeyOz nanocatalysts were studied by means of X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), ultraviolet confocal Raman (Raman), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS, XAES), and hydrogen temperature-programmed reduction (H2-TPR). Furthermore, the structure–activity relationship between the structure of CuxO-FeyOz nanocatalysts and the performance of formaldehyde ethynylation was discussed. The results show that Fe3+ deposited preferentially on the edges and corners of the Cu2O surface, and a redox reaction between Fe3+ and Cu+ occurred, forming CuxO-FeyOz nanoparticles containing Cu+, Cu2+, Fe2+, and Fe3+. With the increase of the Fe/Cu ratio, the content of CuxO-FeyOz increased. When the Fe/Cu ratio reached 0.8, a core–shell structure with Cu2O inside and a CuxO-FeyOz coating on the outside was formed. Because of the large physical surface area and the heterogeneous structure formed by CuxO-FeyOz, the formation of nonactive Cu metal is inhibited, and the most active species of Cu+ are exposed on the surface, showing the best formaldehyde ethynylation activity.

Influence of the Substrate, Process Conditions, and Postannealing Temperature on the Properties of ZnO Thin Films Grown by the Successive Ionic Layer Adsorption and Reaction Method

“…In addition, vibrational peaks at around 147, 214, and 644 cm –1 appeared for samples grown on the Cu foil. These additional phonon modes appeared close to 145, 216, 284, and 493 cm –1 can be attributed to the Cu 2 O phase and those close to 298, 330, 346, and 626 cm –1 can be attributed to the CuO phase. − These observations indicate the possibility of the facile Cu x O/ZnO ( x = 1, 2) junction formation by postannealing at a temperature as low as 250 °C and are also consistent with the XRD patterns shown in Figure b. From both XRD and Raman analyses, it can be concluded that for depositing single-phase highly c -axis-oriented ZnO films, it may be better to use sonication step(s)-less SILAR process irrespective of the substrate type and postannealing at 250 °C for 1 h is required for facile formation of Cu-oxide/ZnO heterojunction when Cu foil is used.…”

A Facile and Environmentally Friendly Approach for Lead Recovery from Lead Sulfate Residue via Mechanochemical Reduction: Phase Transformation and Reaction Mechanism

“…The results reveal that bivalent copper was quickly reduced to elemental copper in the ball milling process. This also reflects that divalent copper could be easily reduced, which was in good accordance with the previous reports. − According to Figure f, characteristic peaks of zinc in the raw materials at 1022.3 and 1045.3 eV correspond to Zn 2p 3/2 and Zn 2p 1/2 in zinc oxide. − In the ball milling process, the characteristic peaks of zinc have not changed, indicating stable chemical properties of zinc oxide.…”

Biochar prepared from Fe‐rich sludge as suitable microbial carriers for facilitating biodegradation of phenanthrene in soil

“…1 illustrates, FB500 showed apparent Fe2p peaks at 712.1 eV (Fe 3+ ) and 710.3 eV (Fe 2+ ). 43 The molar ratio of Fe 2+ :Fe 3+ on the surface of FB500 calculated from the peak areas of Fe 2+ and Fe 3 + was 1.48. The presence of Fe in different valences indicated that Fe oxide was formed which should be the source of magnetism.…”