Electron spectroscopic studies of copper in catalysts for methanol synthesis

Exchange and reduction of Cu2+ ions in clinoptilolite

“…Consequently, d-d transitions are expected. Thus, this peak can be assigned to a spin-allowed transition 2 E g → 2 T g for Cu 2+ ions, e.g., [Cu(H 2 O) 6 ] 2+ [53,54] and Cu 2+ in the solid Al 2 O 3 matrix [55]. These cations should be coordinated with water molecules and oxygen from the zeolite framework, so that the coordination number of these cations is satisfied.…”

In situ XRD and HRTEM studies on the evolution of the Cu/ZnO methanol synthesis catalyst during its reduction and re-oxidation

“…13 ES studies of the solid solutions at 5000-50000 cm À1 showed copper cations forming oxygen-containing small clusters Cu 21 -O-Cu 21 with the strongly distorted, almost flat-square, oxygen coordination of Cu 21 . 17 The hydrogen treatment at temperatures below 573 K results in the reduction of the majority of the copper ions from the a.m.-ZnO followed by the copper diffusion to the a.m.-ZnO surface. XRD data allow the hypothesis that metallic copper forms 3-4 nm crystallites which are epitaxially bonded to the ZnO.…”

Process Intensification of the Hydrogen Production Reaction Using a Carbon Membrane Reactor: Kinetics Analysis

“…The role of ZnO is an essential component of the Cu‐based catalyst, which segregates the Cu species for CuO/ZnO/Al 2 O 3 . The synergy effect between ZnO and CuO can improve the overall thermal stability of the catalyst . In summary, the result shows that the present Cu‐based catalyst has been synthesized successfully, and it is anticipated to exhibit good catalytic properties.…”