Preparation and Evaluation of Copper–Manganese Oxide as a High-Efficiency Catalyst for CO Oxidation and NO Reduction by CO

Abstract

In this work, highly efficient Cu x −Mn composite catalysts (0 ≤ x ≤ 0.20) were synthesized by an improved hydrothermal−citrate complex method and tested in the catalytic total oxidation of CO and the removal of NO by CO. The influence of Cu on manganese oxide materials was characterized by several techniques, including FESEM, HRTEM, XRD, BET analysis, H 2 TPR, O 2 TPD, XPS, and DRIFTS. Possible reaction mechanisms for the NO + CO model reaction and CO oxidation were also tentatively proposed. The Cu-modified manganese oxide materials showed higher catalytic activity in CO oxidation and the selective catalytic reduction (SCR) of NO with CO than pure MnO x materials. The improved catalytic activity in CO oxidation observed for the copper−manganese oxide catalyst was associated with a greater amount of adsorbed oxygen species and high lattice oxygen mobility due to the formation of a Cu 1.5 Mn 1.5 O 4 spinel active phase (CuFurthermore, in terms of the CO-SCR model reaction, the surface-dispersed Cu x+ −O 2− −Mn y+ active species could be reduced to a Cu + −□−Mn (4−x)+ active species, which was considered to be the primary active component in the reduction of NO by CO. The results of the catalytic performance testing indicated that Cu 0.075 Mn had the highest catalytic activity in CO oxidation, whereas Cu 0.15 Mn exhibited the best CO-SCR catalytic performance.

Catalytic Behaviour of Flame-Made CuO-CeO2 Nanocatalysts in Efficient CO Oxidation

“…For CuO-CeO 2 catalysts, the lattice fringes of 0.29-0.32 nm presenting on Figure 2a-d can be indexed to the (111) crystal planes of CeO 2 . It is worthy of note that the 14% CuCe sample exhibits the smallest lattice spacing of 0.29 nm, which is in agreement with the formation the most solid solutions observed in XRD, suggesting the existence of strongest synergistic interaction between the active components and the support [22]. Importantly, the lattice fringes of the 14% CuCe sample displays lattice distortions (which include bending and dislocation), as depicted in Figure 2e, which are induced by the copper ions dopants lowering the energy for oxygen vacancies segregation and mobility of lattice oxygen [23].…”

Removing NOx, CO and HC from automobile exhaust based on chemical looping combustion

“…The difference in the simultaneous removal performance between Cu10/Al90 and Ni10/Al90 probably was related to the amounts of the reductive species at the steady reaction stage …”

“…The difference in the simultaneous removal performance between Cu10/Al90 and Ni10/Al90 probably was related to the amounts of the reductive species at the steady reaction stage. 23,37 (a) (b) In order to examine the differences between the reductive species of the Cu10/Al90 and Ni10/Al90 samples, XRD characterizations were implemented. Figure 7 shows the XRD patterns for the Cu10/Al90 and Ni10/Al90 samples obtained at = 0.95.…”

“…Copper, nickel (Ni‐), manganese (Mn‐) and iron (Fe‐)based catalysts have been widely studied for the NO–CO reaction. In certain cases, Cu‐based catalysts exhibit higher activity than PGM catalysts . Liu et al .…”

“…In certain cases, Cu-based catalysts exhibit higher activity than PGM catalysts. [21][22][23][24] Liu et al investigated NO removal with CO over CuO-CoO x supported on Ce 0.67 Zr 0.33 O 2 , and showed that when the reaction temperature was >350 ∘ C, conversions of NO and CO both achieved 90% under the gas hourly space velocity (GHSV) of 24 000 h −1 . 25 Zhang et al synthesized a MnO x -CuO/TiO 2 catalyst modified with Ni and found that the highest NO conversion reached 85.4% at 350 ∘ C. 26 However, most studies were carried out under a simple reaction atmosphere, which contained only NO and CO. Few reports have examined reaction atmospheres approaching typical automobile exhaust.…”