Comparison of Cu and Ag Catalysts for Epoxidation of Higher Olefins

Hydrogenation of 3,4-epoxy-1-butene over Cu–Pd/SiO2 catalysts prepared by electroless deposition

“…The latter was formed by the isomerization of EpB to the more thermodynamically-stable a,b-unsaturated aldehyde, while 1,3-butadiene was formed by the thermodynamicallyfavored reaction of EpB with Cu 0 sites to form an oxidized Cu site and 1,3-butadiene. This is in agreement with the results of Monnier and Hartley [52] for the interaction of EpB with Cu/aAl 2 O 3 catalysts. The fact that the u Cu = 0.9 catalyst in Table 2 produced substantial amounts of epoxybutane and n-butanal, indicative of Pd catalysts and not of Cu/SiO 2 catalysts, confirms that the Cu coverage on Pd is not monodisperse and agrees well with the CO chemisorption data.…”

“…Thus, the observed effects of Cu deposition on Pd with respect to C-O hydrogenolysis are perhaps more indicative of the reactivity of bifunctional Cu-Pd sites. Based on the oxophilic nature of Cu [7,8,52], the Cu portion could function to activate the epoxy end of the EpB molecules towards ring opening, while the Pd site stabilizes the terminal, p-allylic [53] portion of the adsorbed intermediate. Controlled hydrogenation of this adsorbed intermediate should result in the formation of unsaturated alcohols and aldehydes due to the selectivity of Cu sites for C O bond hydrogenation.…”

Epoxidation of olefins and α,β-unsaturated ketones over sonochemically prepared hydroxyapatites using hydrogen peroxide

“…Catalytic olefin epoxidations have been extensively studied over the last two decades employing a variety of catalysts such as Ti [5], Mn [6], W [7], Re [8] and also using acidic and basic metal oxides such as hydrotalcites [9] and alumina [10]. Other methods reported involve reagents and catalysts namely, sodium hypochlorite [11], dioxiranes [12], sodium perborate in the presence of a phase-transfer reagent [13], alumina supported KF [14], t-butyl hydroperoxide in the presence of a titania-silica catalyst [15], tertiary arsine oxides and H 2 O 2 [16], Ti(IV) silsesquioxane/MCM-41 [17], Ti(IV)/Sn(Ge)(IV)/MCM-41 [18], modified Ti-MCM-41 [19], Mo(VI)/MCM-41, Cu and Ag catalysts [20], porphyrin-based catalysts [21], molybdenum silicate [22], modified natural phosphates [23]. Another widely used method is the peroxy acids (such as m-chloroperoxybenzoic acid) catalyzed epoxidation [24].…”

A density functional theory study of partial oxidation of propylene on Cu 2 O(0 0 1) and CuO(0 0 1) surfaces

“…Metallic copper easily oxidizes to Cu + and then Cu 2+ under reaction conditions in the presence of O 2 therefore it has not been taken into account during the study [40]. In the current study, the behavior of the Cu 2 O(0 0 1) and CuO(0 0 1) surfaces for epoxidation reaction were investigated via DFT method and the results were demonstrated in two parts.…”

“…Onal et al suggested that isolated ionic Cu 2+ species were responsible for propylene epoxidation by O 2 [34]. Metallic copper phase was reported to be thermodynamically unfavorable under epoxidation reaction conditions and easily oxidized to Cu 2 O and further to CuO [40]. On the other hand, light-induced Cu nanoparticle supported on the SiO 2 gave high PO selectivity (50%) at a certain light intensity with relatively low propylene consumption [41].…”