Novel Coassembly Route to Cu−SiO₂ MCM-41-like Mesoporous Materials

Abstract

A series of mesostructured Cu-SiO2 composites have been synthesized with sodium metasilicate (Na2SiO3) and cuprammonia nitrate (Cu(NH3)4(NO3)2) respectively used as Si and Cu sources. The synthetic procedures were conducted at room temperature, and cetyltrimethylammonia bromide was used as a template. Under our experimental conditions, ordered mesoporous Cu-SiO2 composites could be obtained with a copper content up to 16.8 wt %. Average pore diameters (2.80-3.15 nm), wall thickness (1.30-2.20 nm), and specific surface area (1020-690 m2/g) are found to vary linearly with copper content (0-16.8 wt %). Results of thermal gravimetry-differential thermal analysis reveal the collapse temperature of the order structure starts at approximately 1250 K for mesoporous Cu-SiO2 with 16.8 wt % copper content. As indicated by the outcomes of inductively coupled plasma and X-ray photoelectron spectroscopy studies, copper is mainly incorporated inside the pore wall rather than embedded on the wall surface. Copper species strongly interact with silica, and calcination at high temperatures cannot cause phase separation between silica and copper oxide. Cu status in mesoporous Cu-SiO2 composites is similar to that in copper silicate in neighboring structures. Based on the results, a S+ I- I+ I- mechanism is proposed in which copper entities are surrounded by silicon species during synthesis of the mesostructured composite.

Synthesis of ternary mesoporous Cu-Zn-SiO2 materials at ambient temperature and their application for the water gas shift reaction

“…1. As the metal content increased, the peak intensity decreased, which was different from the results of Guo et al [15]. According to their report, the samples with copper incorporation had to some extent a more regular structure than the pure silica sample.…”

“…Its application in heterogeneous catalysis is a promising field, while the pure silica MCM-41 showed very limited catalytic activities. It is necessary to incorporate metals into the silicate framework to create active sites for catalytic reactions, such as Al, Ti, Cr, V, Sn, Co, Pd, Fe, Ga, Zr, Mn and Cu, [8][9][10][11][12][13][14][15]. Hartmann et al synthesized CuZnMCM-48 at 373 K [16].…”

Synthesis, Characterization and Catalytic Performance of Well-Ordered Crystalline Heteroatom Mesoporous MCM-41

“…Low angle XRD patterns of the samples are presented in Figure 1. All samples show an intense broad diffraction peak at very low 2θ angle of 0.7 • -1.7 • , with an overlapping broader feature at 2 • -7 • , which can be respectively attributed to the (1 0 0) diffraction peak and the overlapping pair of (1 1 0) and (2 0 0) diffraction peaks, indicating that the samples have good structural order and the obvious mesoporous structure of MCM-41 [17].…”

“…Extended X-ray absorption fine structure (EXAFS) spectroscopy [22] is one of the most powerful structural characterization methods, especially for interface-confined effects, due to its sensitivity to the three-dimensional short-range order (typically 0-8 Å) and chemical state, including near-neighbor species, distance (R), coordination number (N), and disorder in bond distance (σ 2 ). Figure 4a* shows the K 3 -weighted spectra of Cry-Ni and NiO, which are the Fourier transformed spectra of Ni K-edge EXAFS spectra in the range of k = 2-6 Å.…”

Synthesis and Characterization of Novel Super Microporous Tin-doped Zirconium Oxide

“…Due to their well-defined pore size, large surface area, large pore volume and the potential application used as catalysts, sorbents and separators, mesoporous materials have attracted much attention of researchers. 1 Studies of incorporating most of the transition metals [2][3][4][5][6][7] and some main group elements such as B, 8 Ga, 9 In, 10 etc. into the walls of mesoporous silica materials, e.g.…”