Spherical V-Fe-MCM-48: The Synthesis, Characterization and Hydrothermal Stability

Abstract

Spherical MCM-48 mesoporous sieve co-doped with vanadium and iron was successfully synthesized via one-step hydrothermal method. The material was characterized by X-ray diffraction (XRD), nitrogen adsorption-desorption isotherms, inductively coupled plasma (ICP), scanning electron microscopy (SEM), transmission electron microscopy (TEM), diffuse reflectance UV-vis spectra, and X-ray photoelectron spectra (XPS) techniques. Results indicated that the V-Fe-MCM-48 showed an ordered 3D cubic mesostructure with spherical morphology, narrow pore size distribution and high specific surface area. Most of vanadium and iron atoms existing as tetrahedral V4+ and Fe3+ species were co-doped into the silicate framework. The particle sizes of V-Fe-MCM-48 were smaller and the specific area was much higher than those of of V-MCM-48. Additionally, the synthesized V-Fe-MCM-48 exhibited improved hydrothermal stability compared with the pure MCM-48.

Iron promotion of V‐HMS mesoporous catalysts for ultra‐deep oxidative desulfurization

“…Since iron and vanadium were introduced into the silica lattice, and the Pauling radius of Fe 3+ (0.64 Å) or V 4+ (0.58 Å) is greater than that of Si 4+ (0.42 Å), the lattice was caused to expand . It was confirmed that iron and vanadium were uniformly incorporated into the lattice . However, with the incorporation of iron and vanadium, the intensity of the diffraction peak decreases markedly, which results from the disorder of the mesoporous structure.…”

The influence of the small platinum clusters on hydrogen sorption properties

“…Analysis of HR-TEM micrographs excluded presence of ordered structures typical for mesoporous silica systems like SBA or MCM [20,21] -Fig. 2.…”

Oriented Decoration in Metal-Functionalized Ordered Mesoporous Silicas and Their Catalytic Applications in the Oxidation of Aromatic Compounds

“…Mesoporous silica is well-known for its advanced properties of high specific surface area, high porosity and well-defined pore system, which are ideal characteristics as molecules reaction zone [47][48][49][50]. Besides, due to the narrow pore size distribution, the growth of metal particles will be significantly limited in the confined channels.…”

“…To achieve this progress, many efforts have been put forward, including the direct hydrothermal method (DHT) [78,79], template ion-exchange method (TIE) [80], and wet impregnation method [81]. Particularly, in these methods, DHT is considered to be predominant due to its simplicity in the synthesis procedure, the controllable hydrolysis-condensation speed and high efficiency in incorporating the heteroatoms into the framework, while the rest are liable to induce the formation and aggregation of crystalline metal oxide on the surface of silica, causing the elution of metal active sites in the liquid-phase reactions [49,82]. However, the DHT method is restricted by the rigorous synthetic conditions, especially by pH value [83].…”

“…Xie and his co-workers [93] utilized the mesoporous fiber-like nanospheres as the matrix to support manganese, and the fiber-like pore wall and cross-linking channel further promote the diffusion of reactant molecule. From our previously report [49], as shown in Figure 10, spherical MCM-48 co-doped by Fe and V was synthesized through one-step hydrothermal method and emerged as the catalysts for the oxidation of aromatic benzene or phenol. During the catalytic process, the spherical catalysts exhibited much higher surface area which is favorable for the dispersion of the active metals, and the regularly spherical morphology would speed up the mass transferring leading to the improved catalytic activity [82,92].…”