Mesostructured vanadium-magnesium oxides (V-Mg-O) with various morphologies weresynthesized at room temperature using MgCl2 and V2O5 as source materials and a large number of surfactants as templates. It was found that, among the surfactants employed, the quaternary ammonium surfactants with long alkyl chains, such as cetyltrimethylammonium bromide (CTAB), or the nonionic surfactant Triton-X 100 could template V-Mg-O mesostructures. In the former case, the synthesized specimen had a lamellar structure and nanofibrous morphology. In the latter case, the specimen had a lamellar structure but a particulate morphology. Among the binary mixtures of cationic, anionic, or nonionic surfactants employed, only the combinations between a quaternary ammonium surfactant and hexadecylamine (HDA) were effective in templating a lamellar mesophase with nanofibrous morphology. The binary surfactants were more effective than the single surfactants in generating a higher regularity of the lamellar mesostructure. Mesostructured V-Mg-O could be synthesized even using binary mixtures consisting of HDA and a quaternary ammonium surfactant with a short alkyl chain, such as benzyltrimethyl (neither of the two was effective when used alone). The mesostructured V-Mg-O nanofibers synthesized with binary mixtures of surfactants were more stable during heating at high temperatures than those synthesized with a cationic surfactant alone.

Hexagonal mesoporous Co–Ti oxides were synthesized via a supramolecular assembly route, using a non-ionic surfactant, polyoxyethylene fatty alcohol (AEO9). The textural and electronic properties of the specimens were characterized by means of X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), high resolution transition electron microscopy (HRTEM) and N2-physisorption at 77 K. The application of the mesoporous Co–Ti oxides in the catalytic oxidation of cyclohexane was explored.

Mesostructured V-Mgoxides were synthesized using the surfactant cetyltrimethylammonium bromide (CTAB) as template, V2O5, V(acac)3 (vanadium acetylacetonate), or NH4VO3 as vanadium source, and Mg(NO3)2, MgCl2, MgSO4, (MgCO3)4

Magnesium containing vanadium mesoporous materials were synthesized using vanadium(V) oxide and magnesium nitrate as sources and cetyltrimethylammonium bromide (CTAB) and the mixture of CTAB andhexadecylamine(HDA)as templates.Theeffects of theMg/Vmolar ratioandthe surfactant concentration in the initial batches, the pH employed, and the length of aging time on the structural properties of the synthesized materials were investigated. Both CTAB alone and the mixture CTAB + HDA were effective in templating magnesium containing vanadium mesoporous materials, with a larger average pore size in the latter case. The degree of crystallinity of the mesoporousV-Mg-Owas found to increase with increasing surfactant concentration in the initial batches. However, a too large amount of surfactant increased tremendously the viscosity of the system, generating difficulties in the preparation. At a given pH, the degree of crystallinity of the mesoporous materials increased with increasing Mg/V molar ratio in the initial batch, attaining a maximum followed by a decrease. At a given Mg/V molar ratio in the initial batch, the degree of crystallinity increased with increasing pH, passed though an optimum for a pH ) 7, and then decreased. The analysis of the composition of the mesoporous materials revealed that the amount of magnesium included in the samples was small and increased only slightly with increasing amount in the initial batches; the increase of the pH increased, however, much more the amount of Mg included in the mesoporous materials. The stability toward heating at various temperatures increased with increasing amount of magnesium in the samples. Possible explanations for the effects found are suggested.

Mesostructured vanadium-magnesium oxides (V-Mg-O) were synthesized using vanadium pentoxide and magnesium nitrate as sources and cetyltrimethylammonium bromide (CTAB) or the mixture of CTAB and hexadecylamine (HDA) as template. The effects of surfactant concentration,pHof the reaction medium, aging time, and temperature as well as aging mode (static or dynamic) were systematically investigated. The pH of the reaction medium and the surfactant concentration and nature were found to be the key parameters in the formation of V-Mg-O mesophases. When CTAB was employed alone as template and its concentration was higher than the critical micelle concentration, single lamellar mesophases were obtained in both acidic and neutral media. When the mixture of surfactants was used as template and its concentration was sufficiently low, only microporous phases were obtained in strongly acidic media (pHe 4), even at elevated aging temperatures and/or for long aging times. A mixture of mesophases could be, however, obtained in weakly acidic and neutral media (pH ) 4-7). At high surfactant concentrations, a single lamellar structure was generated in strongly acidic media and a mixture of mesophases in the weakly acidic and neutral ones. Only amorphous solids were generated in the basic range of pH, regardless of the surfactant concentration employed. With the change in aging time, numerous metastable phases have been identified, particularly in weakly acidic and neutral media.Somecomments about the mechanisms of formation of the mesophases conclude the paper.