Investigation of the Structure of MCM‐41 Samples with a High Copper Content

Abstract

AbstractA 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), N2‐adsorption isotherms, high‐resolution transmission electron microscopy (HRTEM), inductively coupled plasma (ICP), temperature‐programmed reduction (H2‐TPR), X‐ray photoelectron spectroscopy (XPS), Fourier‐transform infrared spectroscopy (FTIR), UV‐vis spectroscopy, electron‐spin resonance (ESR) and 29Si 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 m2 g–1 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).