Enhancing the Ethynylation Performance of CuO-Bi2O3 Nanocatalysts by Tuning Cu-Bi Interactions and Phase Structures

Abstract

Catalytic systems consisting of copper oxide and bismuth oxide are commonly employed for the industrial production of 1,4-butynediol (BD) through ethynylation. However, few studies have investigated the influence mechanism of Bi for these Cu-based catalysts. Herein, a series of nanostructured CuO-Bi2O3 catalysts were prepared by co-precipitation followed by calcination at different temperatures. The obtained catalysts were applied to the ethynylation reaction. The textural and crystal properties of the catalysts, their reduction behavior, and the interactions between copper and bismuth species, were found to strongly depend on temperature. When calcined at 600 °C, strong interactions between Cu and Bi in the CuO phase facilitated the formation of highly dispersed active cuprous sites and stabilized the Cu+ valency, resulting in the highest BD yield. Bi2O3 was completely absent when calcined at 700 °C, having been converted into the spinel CuBi2O4 phase. Spinel Cu2+ was released gradually to form active Cu+ species over eight catalytic cycles, which continuously replenished the decreasing activity resulting from the formation of metallic Cu and enhanced catalytic stability. Moreover, the positive correlation between the in-situ-formed surface Cu+ ions and BD yield suggests that the amount of Cu+ ions is the key factor for ethynylation of formaldehyde to BD on the as prepared CuO-Bi2O3 catalysts. Based on these results and the literature, we propose an ethynylation reaction mechanism for CuO-based catalysts and provide a simple design strategy for highly efficient catalytic CuO-Bi2O3 systems, which has considerable potential for industrial applications.

Heterogeneous catalysis for thioanisole oxidation using hydrogen peroxide and Copper, Nickel and Zinc tungstates prepared by the polymeric precursor method

“…According to the literature, ZnWO4 also has blue-green emission [38], however oxygen vacancies induce red shift emission due deep defects in the lattice [34,39]. intense signal in 400-550 °C, at higher temperature than the typical CuO peak (200-350 °C) [40,41]. This fact is accordance with the XRD results, suggesting that the copper is present in the tungstate structure, and not in a secondary copper oxide phase.…”

Green synthesis of Cu/Cu2O/CuO nanostructures and the analysis of their electrochemical properties

“…Evidently cupric oxide has high content than cuprous oxide which reveals its higher intensity at 42˚ and 62˚ and demonstrating that the varied phase has main proportions of CuO/Cu 2 O with the highly oriented crystalline Cu/Cu 2 O/ CuO phase. The mean particle size of Cu/Cu 2 O was calculated from the line broadening of Cu/Cu 2 O/CuO [200] peak (2θ = 42°) by Scherrer equation [32,62].…”

“…2f shows combined phases of spherical like structures growing within the nano-micro structures of the prepared Cu/Cu 2 O/CuO nanocomposites. Literature provided evidence that the Cu/Cu 2 O/CuO mixed phases and nano-micro structures can be used in different applications such as energy and biomedical technology[31,32]. HRTEM (Fig.…”

High-Performance Chlorine-Doped Cu2O Catalysts for the Ethynylation of Formaldehyde

“…However, only slight Raman peaks were observed at 1118 cm −1 and 1595 cm −1 in Cu2O-Cl(2) indicating the existence of a very small amount of polyacetylene. In general, the formation of polyacetylene is due to two factors: (1) metallic Cu catalyzes the polymerization of acetylene and (2) the acidic center favors the formation of polyacetylene [20]. According to the XRD and XAES results of used samples, metallic Cu was observed in Cu2O-NO3, but only a small amount of metallic Cu existed in Cu2O-Cl (2).…”

“…Namely, metallic Cu will cause the formation of polyacetylene by-products and rapid deactivation of the catalyst [17][18][19]. Literature mainly reports introducing Bi 2 O 3 to inhibit over-reduction of Cu 2+ [15,19,20].…”