Investigation of the structure of MCM-41 samples with a high copper content

A series of MCM-41s with a high copper content were synthesized at room temperature from sodium metasilicate (Na2SiO3) as the silicon source, tetraamminecopper((II)) nitrate [Cu(NH3)(4)(NO3)(2)] as the copper source and cetyltrimethylammonium bromide (CTABr) as the template. The resulting material was characterized by using the following characterization techniques: X-ray diffraction (XRD), N-2-adsorption isotherms, high-resolution transmission electron microscopy (HRTEM), inductively coupled plasma (ICP), temperature-programmed reduction (H-2-TPR), X-ray photoelectron spectroscopy (XPS), Fourier-transform infrared spectroscopy (FTIR), UV-vis spectroscopy, electron-spin resonance (ESR) and Si-29 magic-angle sample spinning nuclear magnetic resonance (MAS NMR) spectroscopy. The characterization techniques demonstrated the following: i) the copper atoms are incorporated into the framework of MCM-41 and ii) the copper species in the samples are in a distorted octahedral coordination environment, with between four and six oxygen atoms in the first coordination sphere. The maximum copper content determined by ICP was 26 wt.-% in the ordered mesoporous sample with a surface area of 525 m 2 9 I and an average pore diameter of 3.1 nm. The synthesized materials exhibited a high activity for nitrogen monoxide (NO) reduction by carbon monoxide (CO).