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

Authors


  • The National Natural Science Foundation of China (#20173026 and #10074031) and the Modern Analysis Center of Nanjing University provided funding for this work.

Abstract

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), 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).

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