Effect of the means of preparation of nanodispersed CuO/MgO catalysts on their activity in the oxidation of CO

Abstract

A method is proposed for obtaining copper-containing catalysts by means of mechanical mixing of previously formed monodispersed CuO nanoparticles (mean particle diameter 12 nm) with MgO. Higher activity was found for these catalysts in the oxidation of carbon monoxide than for the analogous copper-containing systems prepared by impregnation and deposition of cupric oxide nanoparticles from colloidal solution.Key words: cupric oxide nanoparticles, thermal decomposition of malachite, crystallite size, CO oxidation.Nanoparticles of metals and metal oxides with diameter not greater than 100 nm display unique properties, which are different from those characteristic for the bulk substances. The thermal, magnetic, optical, and catalytic characteristics of these materials are altered due to the effect of particle size [1-3].Catalysts derived from copper and its oxides are commonly used in many chemical reactions, including the preparation of methanol and higher alcohols from synthesis gas, the oxidation of organic and organosulfur compounds, the removal of CO and hydrocarbons from exhaust gases, water displacement, and steam reforming of low-molecular-weight alcohols with the production of hydrogen [1][2][3][4][5][6]. This common use of copper catalysts in various chemical reactions is attributed to their high activity related to facile electron transfers between copper in various oxidation states (Cu 0 , Cu 1+ , Cu 2+ ). We should also expect dimensional effects in the use of highly-dispersed copper catalysts in the low-temperature oxidation of CO and organic compounds.Various methods are used to prepared nanodimensional particles of copper and copper oxides, including template synthesis, coprecipitation, thermal decomposition, pyrolysis, photolysis, CVD synthesis, reduction of alcohols using various agents, and pulse wave treatment [2, 3, 7-10].In the present work, we studied the feasibility of controlling the size of CuO particles supported on MgO by altering the conditions of their preparation and investigated the effect of the size factor on the catalytic properties of the systems obtained in CO oxidation taken as a model reaction. EXPERIMENTALThree methods were used to prepare the CuO/MgO catalysts: 1) deposition from colloidal solution, 2) mechanical mixing of the components, and 3) impregnation.The deposition of cupric oxide nanoparticles from colloidal solution is attractive since it permits us to obtain highly dispersed catalysts with a narrow distribution of particles of the active component on the support surface but a difficulty is 172 0040-5760/08/4403-0172

Optical and Electrical Properties of Solvothermally Synthesized Manganese Doped Cuprous Oxide Nanoparticles

“…It is also an ideal compound using as a dilute magnetic semiconductor (DMS).It has been used as heterogeneous catalysts in many important chemical processes and oxidation of carbon monoxide, hydrocarbon and phenol in super critical water [5]. Various methods are used to prepare nanoparticles of copper oxides, including sol-gel, precipitation-stripping, solid-state reaction, alkoxide based synthesis, precipitation-pyrolysis and thermal decomposition [6][7][8][9][10][11][12][13][14]. Among these techniques for the synthesis of copper oxide nanoparticles, solvothermal process is a novel method; it is much faster and more economical [15].…”

Synthesis of Transition Metal Oxide Based MgO Nanocomposites by a Simple Precursor Approach

“…MgO is one of the most interesting metal oxides that have been used in various applications such as catalysis [1,2], toxic waste remediation [3], pharmaceuticals [4], electro-optical devices [5], ferroelectrics [6], etc. Recently, transition metal oxide based MgO nanocomposites have gained a considerable interest in the field of catalysis [7][8][9]. Typical examples of transition metal oxide based MgO nanocomposites include CuO-MgO [9], TiO 2 -MgO [10], ZnO-MgO [11], Fe 2 O 3 -MgO [12], MgO-Y 2 O 3 [13], MgO-NiO [14,15], Co 3 O 4 -MgO [16] and MgO-ZrO 2 [7].…”

“…Recently, transition metal oxide based MgO nanocomposites have gained a considerable interest in the field of catalysis [7][8][9]. Typical examples of transition metal oxide based MgO nanocomposites include CuO-MgO [9], TiO 2 -MgO [10], ZnO-MgO [11], Fe 2 O 3 -MgO [12], MgO-Y 2 O 3 [13], MgO-NiO [14,15], Co 3 O 4 -MgO [16] and MgO-ZrO 2 [7]. MgO-Co 3 O 4 and MgO-NiO nanocomposites have several applications in catalysis [16][17][18].…”

“…Furthermore, these nanocomposites have a great potential for magnetic applications (e.g. spintronics) since Co 3 O 4 and NiO nanoparticles are known to possess interesting magnetic properties [19,20].Various synthetic methods have been reported for the preparation of transition metal oxide based MgO nanocomposites which include sol-gel [10], solvothermal [11], precipitation [12], impregnation [9,14] and mechanical mixing [9]. In the present study, MgO-Co 3 O 4 and MgO-NiO nanocomposites have been prepared using a simple precursor approach.…”