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Catalytic oxidative desulfurization (ODS) using titanium silicate catalysts has emerged as an efficient technique for the complete removal of organosulfur compounds from automotive fuels. However, the precise control of highly accessible and stable-framework Ti active sites remains highly challenging. Here we reveal for the first time by using density functional theory calculations that framework hexa-coordinated Ti (TiO6) species of mesoporous titanium silicates are the most active sites for ODS and lead to a lower-energy pathway of ODS. A novel method to achieve highly accessible and homogeneously distributed framework TiO6 active single sites at the mesoporous surface has been developed. Such surface framework TiO6 species exhibit an exceptional ODS performance. A removal of 920 ppm of benzothiophene is achieved at 60°C in 60 min, which is 1.67 times that of the best catalyst reported so far. For bulky molecules such as 4,6-dimethyldibenzothiophene (DMDBT), it takes only 3 min to remove 500 ppm of DMDBT at 60°C with our catalyst, which is five times faster than that with the current best catalyst. Such a catalyst can be easily upscaled and could be used for concrete industrial application in the ODS of bulky organosulfur compounds with minimized energy consumption and high reaction efficiency. [ABSTRACT FROM AUTHOR]

Zeolite Beta single crystals with intracrystalline hierarchical porosity at macro‐, meso‐, and micro‐length scales can effectively overcome the diffusion limitations in the conversion of bulky molecules. However, the construction of large zeolite Beta single crystals with such porosity is a challenge. We report herein the synthesis of hierarchically ordered macro‐mesoporous single‐crystalline zeolite Beta (OMMS‐Beta) with a rare micron‐scale crystal size by an in situ bottom‐up confined zeolite crystallization strategy. The fully interconnected intracrystalline macro‐meso‐microporous hierarchy and the micron‐sized single‐crystalline nature of OMMS‐Beta lead to improved accessibility to active sites and outstanding (hydro)thermal stability. Higher catalytic performances in gas‐phase and liquid‐phase acid‐catalyzed reactions involving bulky molecules are obtained compared to commercial Beta and nanosized Beta zeolites. The strategy has been extended to the synthesis of other zeolitic materials, including ZSM‐5, TS‐1, and SAPO‐34. [ABSTRACT FROM AUTHOR]

Abstract: Hierarchically dual‐mesoporous TiO2 microspheres have been synthesized by a solvothermal process in the presence of 1‐butyl‐3‐methylimidazolium tetrafluoroborate ([BMIm][BF4]) and diethylenetriamine (DETA) as co‐templates. Secondary mesostructured defects in the hierarchical TiO2 microspheres produce oxygen vacancies, which not only significantly enhance photocatalytic activity in the degradation of methylene blue (1.7 times that with P25) and acetone (2.9 times that with P25), but are also beneficial for lithium storage. Moreover, we propose a mechanism to rationalize the role of this dual mesoporosity of the TiO2 microspheres in enhancing molecular diffusion, ion transportation, and electronic transitions. [ABSTRACT FROM AUTHOR]

Cubic Pd nanocrystals with shape-controlled mesoporous silica shells have been theoretically designed and successfully synthesized for investigating the effect of a porous nanoshell on catalytic performance of the core. Cubic Pd@cubic mesoporous silica keeps activity of all facets and shows highest catalytic activity and enhanced reusability in the hydrogenation of nitrobenzene. [ABSTRACT FROM AUTHOR]

Polyhedral oligosilsesquioxanes (POSS), regarded as the smallest possible particles of silica, are used as carbon source and assembled into hierarchically porous carbon structures by a block copolymer-assisted method. The obtained carbon materials with high specific surface area of over 2000 m 2 g −1 and large pore volume of over 1.19 cm 3 g −1 possess both quite uniform micropores with the size of ~1 nm and highly ordered mesopores with the size of ~4 nm, owing to the molecular-scale templating effect of POSS siloxane cages as well as the good assembly compatibility between the block copolymers and the aminophenyl-functionalized POSS used. The mesopore arrangement can be two-dimensionally hexagonal ( p 6 m ) or body-centered cubic ( Im 3 ¯ m ) by simply adjusting different block copolymers. Nitrogen functionalities with a relatively high content (~4 wt%) can spontaneously be incorporated into those carbon materials. Benifiting from the uniform microporosity and the nitrogen doping, the specific capacitance of the POSS-derived hierarchically porous carbons can reach ~160 F g −1 in ionic liquid electrolyte and ~210 F g −1 in 1 M H 2 SO 4 aqueous electrolyte, when measured at a current density of 0.25 A g −1 in a symmetrical two-electrode cell. More importantly, the highly ordered mesopores can facilitate ions fast transportion to the fine micropores to achieve the excellent power performance. The hierarchial carbon sample with a hexagonal mesostructure and a high mesoporosity displays the best rate capability with 94% and 97% of capacitance retention in ionic liquid and 1 M H 2 SO 4 , respectively, with the current density range from 0.25 to 10 A g −1 . By combining self-assembly strategy with rich POSS chemistry, we believe that many other hierarchical hybrid materials or carbon materials with unique electrochemical properties can be synthesized. [ABSTRACT FROM AUTHOR]

Highly monodispersed platinum-based nanoalloys are the best-known catalysts for the oxygen reduction reaction. Although certainly promising, the durability and stability are among the main requirements for commercializing fuel cell electrocatalysts in practical applications. Herein, we synthesize highly stable, durable and catalytic active monodispersed PtPd nanoparticles encapsulated in a unique one particle@one cell structure by adjusting the viscosity of solvents using mesocellular foam. PtPd nanoparticles in mesocellular carbon foam exhibit an excellent electrocatalytic activity (over 4 times mass and specific activities than the commercial Pt/C catalyst). Most importantly, this nanocatalyst shows no obvious change of structure and only a 29.5% loss in electrochemically active surface area after 5000 potential sweeps between 0.6 and 1.1V versus reversible hydrogen electrode cycles. [ABSTRACT FROM AUTHOR]

Abstract: Unusual partially crystalline ordered mesoporous zirconosilicate doughnuts with Si/Zr ratio as low as 1.5 were synthesized from the aqueous polymerisation of a single source molecular precursor Zr[OSi(Ot-BuO)3]4 without the use of any templating agent. A radial homogenous mesoporosity (4nm) was observed inside these very regular sub-micrometric (600nm) doughnuts. These structures were partially crystallized in hydrothermal conditions (100°C) into an analogous zircon (ZrSiO4) framework. The formation mechanism has been investigated. It is evidenced that chlorine anions Cl− concentration and pH value are essential to achieve the process, even if their role is still a matter of investigations. The obtained materials demonstrated even higher catalytic activity, selectivity and stability in the liquid oxidative dehydrogenation of hydroquinone to 1,4-benzoquinone compared to TS-1 zeolite catalysts and amorphous highly ordered mesoporous zirconosilicate materials. [Copyright &y& Elsevier]

Abstract: A layer of macrocyclic calix[4]arene derivatives has been grafted on the internal surface of the mesochannels of the ordered mesoporous SBA-15 to develop highly efficient trap for heavy transition metal (HTM) ions. To ensure the successful anchoring of calix[4]arene derivatives on the surface of SBA-15, two different types of calix[4]arene derivatives, one with one trimethoxysilane functional group and another with two trimethoxysilane functional groups have been explored. XRD, N2 adsorption and TEM results provide strong evidence that the mesoporous structure of the supporting materials retain their long range ordering throughout the grafting process. Solid-state NMR, TG and FT-IR spectroscopy indicate that both types of calix[4]arene derivatives can be well-anchored on the surface of the wall of SBA-15. Calix[4]arene derivative with only one trimethoxysilane functional group showed high grafting efficiency compared to that with two trimethoxysilane functional groups due to the intramolecular and intermolecular polycondensation between two trimethoxysilane functional groups. The HTM ions extraction capacity in aqueous solution of macrocycle functionalized SBA-15 nanohybrides for a series of HTM ions has been studied. The obtained materials demonstrated very high HTM ions extraction capacity up to 96% for Pb2+ in aqueous solution. [Copyright &y& Elsevier]

Abstract: Highly sensitive and selective nanosensor for labile iron pool (LIP) determination, has been designed and prepared by immobilization of Fluoresceine–Desferrioxamine (Fl–DFO), a bifunctional fluoro-siderophore probe molecule with great affinity for iron ions (pKf =30.7), into highly ordered mesoporous silica structure. Different immobilization methods of Fl–DFO molecules, such as their encapsulation in surfactant micelles used as templating agents for the synthesis of mesoporous silica, direct impregnation into the mesochannels of as-synthesized mesoporous silica and their surface anchoring by covalent binding with propylamine groups implanted by post-synthesis on the internal surface of mesochannels, have been explored. Each nanohybrid has been fully characterized by small angle XRD, TEM, SEM, solid state 29Si and 13C MAS NMR and N2 adsorption–desorption. The fluorescence properties of nanohybrids obtained have been correlated with the immobilization methods, generating interesting information concerning the localization of Fl–DFO molecules in the channels of mesoporous silica. The leaching of Fl–DFO molecules from mesoporous materials has been investigated. The nanosensor prepared by surface anchoring of Fl–DFO at the internal surface of mesochannels showed high performances with no leaching effect and high sensitivity in regards to its responses to ferric ions. Its fluorescence intensity decreased as soon as first FeIII ions are in contact with this nanosensor. A linear relationship between the fluorescence intensity and the ferric ions concentration was observed in low micromolar range. The selectivity of this nanosensor towards other metal ions has also been tested and shown its high affinity to ferric ions. This study can allow the design of a stable, portable, simple, regenerable and cost-effective nanosensor highly sensitive and selective for iron ions with detection limits in the range of cellular LIP in cells, e.g. lower micromolar range. [Copyright &y& Elsevier]

Abstract: The effect of tetraethoxysilane (TEOS), tetrapropoxysilane (TPOS), tetrabutoxysilane (TBOS) and a mixture of tetramethoxysilane (TMOS) and TEOS as silicon co-reactant on the formation of hierarchically structured meso-macroporous aluminosilicates and the tetrahedral aluminium content in the framework using a single molecular alkoxide precursor, (sec-BuO)2–Al–O–Si(OEt)3, has been intensively investigated. The use of alkoxysilane as a co-reactant and highly alkaline media improves the heterocondensation rates between the highly reactive aluminium-alkoxide part of the single molecular precursor and the added alkoxysilanes, and minimizes the cleavage of the intrinsic Al–O–Si linkage. The very unique hierarchical meso-macroporosity was auto-generated by the hydrodynamic flow of solvents released during the rapid hydrolysis and condensation processes of this double alkoxide and the inorganic silica co-reactant. No external structural agent was required to template these porous structures. The particles obtained featured outstanding macrostructure with regular micrometer-sized macrovoids and displaying 3D interconnections. Importantly, the diameter of the micrometer-sized macrovoids found in the final materials and the thickness of the mesoporous walls separating these voids can be tuned by adjusting the reactivity of alkoxysilanes used as co-reactant. Higher reactivity of alkoxysilanes can improve the tetrahedral aluminium content in the meso-macroporous framework and reduce the cleavage of Al–O–Si linkage of the single molecular precursor. These correlations are of primary importance for targeting advanced materials with well defined meso- and macroporosities and tetrahedral aluminium content. [Copyright &y& Elsevier]

Highlights: [•] A novel class of mesoporous ZnO/silica composites was synthesized. [•] The best materials present a high surface area and narrow pore size distribution. [•] The small ZnO particle size is preserved for all materials (except for the ZnO-100). [•] The materials preserving the mesoporous organization display a high photocatalytic activity. [Copyright &y& Elsevier]

Abstract: Mesoporous hexagonal silica CMI-1, MCM-41, SBA-15 and Al-incorporated silica AlCMI-1 with pore sizes of 2, 2.7, 3.8 and 3.6nm, respectively, have been synthesized and used as host materials for the fabrication of optical materials by the encapsulation of direct blue 71 dye. The surface silanol groups of these mesoporous silicas were functionalized by silylation with 3-(aminopropyl)-triethoxysilane or methyltrimethoxylsilicate, which allow a successful doping of organic dye molecules. X-ray diffraction, N2 adsorption, thermogravimetric analysis, infrared, UV–vis diffuse reflectance and solid-state NMR spectroscopy were used to structurally characterize these composite products. It is found that the dye molecules of direct blue 71 have been encapsulated in the pores of MCM-41, SBA-15 and AlCMI-1, whereas attached on the external surface of CMI-1. The steric effect from the pore size of the host materials is significant. Moreover, Al-species in the AlCMI-1 were believed to take an important role in the dye encapsulation, resulting in a larger blue-shift of 21nm than other mesoporous dye/silica composites. [Copyright &y& Elsevier]

To develop high-performance anode materials of lithium ion batteries (LIBs) for practical high energy application, a grain boundaries enriched hierarchically mesoporous MnO/C microsphere composite has been fabricated by an in-situ carbonization process. The mesoporous MnO/C microsphere is constructed by abundant grains and grain boundaries that are uniformly embedded in a carbon matrix. Such unique nanoarchitecture exhibits high tap density and structural stability, and provides 3D continuous transport pathways for electrons and Li-ions, enabling high electrochemical stability and improved lithium storage kinetics. As a consequence, the mesoporous MnO/C electrode delivers ever-increasing specific capacity (1200 mAh g −1 after 100 cycles at 100 mA g −1 ) and excellent rate capability (588 mAh g −1 at 2 A g −1 ). Such superior lithium storage performance suggests that the hierarchically mesoporous MnO/C microsphere electrode should be one of the most promising anode materials for electric vehicle and grid energy storage application. [ABSTRACT FROM AUTHOR]

Nitrogen-doped ordered mesoporous carbons (OMCs) have been synthesized via aqueous cooperative assembly route in the presence of basic amino acids as either polymerization catalysts or nitrogen dopants. This method allows the large-scale production of nitrogen-doped OMCs with tunable composition, structure and morphology while maintaining highly ordered mesostructures. For instances, the nitrogen content can be varied from ∼1 wt% to ∼6.3 wt% and the mesophase can be either 3-D body-centered cubic or 2-D hexagonal. The specific surface area for typical OMCs is around 600 m 2 g −1 , and further KOH activation can significantly enhance the surface area to 1866 m 2 g −1 without destroying the ordered mesostructures. Benefiting from hierarchically ordered porous structure, nitrogen-doping effect and large-scale production availability, the synthesized OMCs show a great potential towards supercapacitor application. When measured in a symmetrical two-electrode configuration with an areal mass loading of ∼3 mg cm −2 , the activated OMC exhibits high capacitance (186 F g −1 at 0.25 A g −1 ) and good rate capability (75% capacity retention at 20 A g −1 ) in ionic liquid electrolyte. Even as the mass loading is up to ∼12 mg cm −2 , the OMC electrode still yields a specific capacitance of 126 F g −1 at 20 A g −1 . [ABSTRACT FROM AUTHOR]

Two dimensional (2D) ZnO nanosheets are ideal system for dimensionally confined transport phenomenon investigation owing to specific surface atomic configuration. Therefore, 2D ZnO porous nanosheets with single-crystal nature and {0001} polar facets, likely display some specific physicochemical properties. In this work, for the first time, 2D ZnO mesoporous single-crystal nanosheets (ZnO-MSN) with {0001} polar facets have been designed and prepared via an intriguing colloidal templating approach through controlling the infiltration speed for the suspension of EG-capped ZnO nanoparticles and polymer colloids. The EG-capped ZnO nanoparticles are very helpful for single-crystal nanosheet formation, while the polymer colloids play dual roles on the mesoporosity generation and {0001} polar facets formation within the mesopores. Such special 2D structure not only accelerates the hole-electron separation and the electron transportation owing to the single-crystal nature, but also enhances the selective adsorption of organic molecules owing to the porous structure and the exposed {0001} polar facets with more O-termination (000-1) surfaces: the 2D ZnO-MSN shows highly selective adsorption and significantly higher photodegradation for positively charged rhodamine B than those for negatively charged methyl orange and neutral phenol, comparing with ZnO nanoparticles (ZnO-NP) and ZnO commercial nanoparticles (ZnO-CNP) with high surface areas. This work may shed some light on better understanding the synthesis of 2D porous single-crystal nanosheet with exposed polar surfaces and photocatalytic mechanism of nanostructured semiconductors in a mixed organic molecules system. [ABSTRACT FROM AUTHOR]

Highlights: [•] Highly ordered mesoporous silica thin films. [•] Control of mesoporous structure and mesochannels orientation. [•] A comprehensive revisit to synthesis parameters. [•] Wettability of different solvent and AFM study. [•] Pore size and surface area determined by Ellipsometry study. [ABSTRACT FROM AUTHOR]

Abstract: A new class of structured mesoporous materials consisting of gallium oxide nanoparticles embedded and stabilised in a silica matrix was designed, synthesised and tested as catalysts for the epoxidation of various alkenes with aqueous hydrogen peroxide. The structure and texture of the mesoporous gallia–silica composites were elucidated by powder X-ray diffraction, isothermal N2 sorption and TEM. The most active epoxidation catalysts are the materials containing 80 and 90% of Ga2O3 nanoparticles. These materials give much higher epoxide yields compared to the parent nanoparticles, thus demonstrating the positive effect of structuring on the catalytic performance. The synthesis of the mesoporous gallia-silica composite catalysts was optimised by investigating the effect of the calcination conditions. Finally, different methods for recycling the catalysts were studied. Mild calcination at 250°C for 3h under controlled N2 flow was identified as the most suitable treatment to retain the catalytic activity upon reuse. [Copyright &y& Elsevier]

Abstract: Mesoporous TiO2 with a hierarchically 3D dendrimeric nanostructure comprised of nanoribbon building units has been synthesized via a spontaneous self-formation process from various titanium alkoxides. These hierarchically 3D dendrimeric architectures can be obtained by a very facile, template-free method, by simply dropping a titanium butoxide precursor into methanol solution. The novel configuration of the mesoporous TiO2 nanostructure in nanoribbon building units yields a high surface area. The calcined samples show significantly enhanced photocatalytic activity and degradation rates owing to the mesoporosity and their improved crystallinity after calcination. Furthermore, the 3D dendrimeric architectures can be preserved after phase transformation from amorphous TiO2 to anatase or rutile, which occurs during calcination. In addition, the spontaneous self-formation process of mesoporous TiO2 with hierarchically 3D dendrimeric architectures from the hydrolysis and condensation reaction of titanium butoxide in methanol has been followed by in situ optical microscopy (OM), revealing the secret on the formation of hierarchically 3D dendrimeric nanostructures. Moreover, mesoporous TiO2 nanostructures with similar hierarchically 3D dendrimeric architectures can also be obtained using other titanium alkoxides. The porosities and nanostructures of the resultant products were characterized by SEM, TEM, XRD, and N2 adsorption–desorption measurements. The present work provides a facile and reproducible method for the synthesis of novel mesoporous TiO2 nanoarchitectures, which in turn could herald the fabrication of more efficient photocatalysts. [Copyright &y& Elsevier]

Abstract: The H4PMo11VO40 heteropolyacid (HPA) was supported at 30wt.% by the dry impregnation method on HMS, CMI-1 and SBA-15 mesoporous materials. The state of the HPA and those of the supports were examined by nitrogen physisorption, X-ray diffraction, (DR) FT–IR and X-ray photoelectron spectroscopies, thermal analysis (TG–ATD) and scanning electron microscopy (SEM). The effect of support on the catalytic behavior of H4PMo11VO40 was studied in the propene oxidation at 350°C. It was shown that the presence of H4PMo11VO40, modifies the textural properties of mesoporous materials (decrease of surface area) without destroying their structure. The interaction support–heteropolyacid leads to the formation of (SiOH2+)(H3PMo11VO40 −) surface species more stable than H4PMo11VO40 species and that appear to be the active sites in the propene oxidation. [Copyright &y& Elsevier]

Abstract: Hierarchical porous architecture with interconnected trimodal micro-meso-macroporous systems constructed from uniform zeolite Zr-doped silicalite-1 nanocrystals has been prepared. The synthesis has been made by using glycerin as a reaction medium via a quasi-solid-state crystallization of hierarchically meso-macroporous zirconosilicate precursor under the effect of the structure directing agent TPAOH. The presence of glycerin is crucial in the synthesis systems to maintain the porous hierarchy. The pores inter-connectivity, Zr location in the framework, the acidity and the catalytic activity have been studied by laser-hyperpolarized 129Xe NMR spectroscopy, UV–visible spectroscopy, temperature-programmed desorption of ammonia and the catalytic isopropylbenzene cracking probe reaction, respectively. The products possess well-defined macrochannels interconnected with mesopores located in the macropore walls, which in turn have been constructed from microporous MFI-type zeolite units. 129Xe NMR study indicated that the hierarchically micro-, meso-, macro-pore systems are homogeneously distributed throughout the final materials and well interconnected, which is important for molecular diffusion. The TPD-NH3 investigation revealed that the hierarchically micro-meso-macroporous materials constructed from zeolite Zr-Silicalite-1 nanocrystals present strong acidity. [Copyright &y& Elsevier]

Abstract: Materials, consisting of H3+ x PMo12− x V x O40 heteropolyacids (HPAs) with x =0–3, supported on a HMS mesoporous pure-silica molecular sieve, have been prepared by means of dry impregnation method and characterized by elemental analysis, X-ray diffraction, transmission and diffuse reflectance (DR) FT-IR, Raman and X-ray photoelectron spectroscopies, nitrogen physisorption and thermal analysis (TG–DTA). The HPA/HMS compositions with HPA loadings from 10 to 50wt.% display uniformly sized mesopores. HPA retains the Keggin structure on the HMS surface and forms finely dispersed HPA species over the whole range of HPA loadings, crystal phases being absent even at 50wt.%. Results demonstrate that HPA/HMS exhibit a higher catalytic activity than bulk heteropolyacids in propene oxidation by molecular oxygen. Furthermore, the supported species allow for an enhanced oxidation catalytic activity (formation of acrolein, acetaldehyde and acetic acid) compared to the mother catalysts. The catalytic performance exhibited by H3+ x PMo12− x V x O40/HMS catalysts was attributed to the fine dispersion of H3+ x PMo12− x V x O40 species on the HMS mesoporous material via physical adsorption. The HPA/HMS systems, with strong acid sites, high redox power and a regular mesoporous distribution, are promising catalysts for the oxidative reactions. [Copyright &y& Elsevier]

Abstract: We proposed here a one-pot route to prepare resorcinol/formaldehyde (RF) resin-based carbon materials with highly ordered mesostructures in an aqueous media. Compared with other techniques, the synthesis is a single-step process; neither prepolymerization nor thermal solidification is needed. The crucial difference to the previous methods is that the commonly used formaldehyde is replaced with hexamine. Hexamine can serve as a release source of formaldehyde to control the kinetics of RF polymerization reaction. The combined use of resorcinol and hexamine allows the accelerated synthesis without disturbing the cooperative self-assembly of RF resin and amphiphilic triblock copolymer. A mesophase transformation from body-centered cubic () to 2-D hexagonal (p6m) structure can be achieved by simply adding 1,3,5-trimethylbenzene to the synthesis. Especially, this synthesis can be performed not only under weakly basic conditions but also under highly acidic conditions, despite that the acid-catalyzed synthesis will result in the formation of the product with a relatively low thermal stability. [Copyright &y& Elsevier]

Abstract: Mesoporous metal oxides (CeO2−δ)–YSZ have been synthesized by a versatile direct synthesis method using ionic cetyltrimethylammonium bromide (CTAB) and different nonionic (block copolymers) as surfactants and urea as hydrolyzing agent. The synthesis was realized at pH=9 using tetraethylammonium hydroxide (TEAOH) as pH mediator. Calcination at 550°C led to the formation of crystalline metal oxides with uniform mesoporosity. The obtained materials have been characterized by thermogravimetric analysis (TG-DTG), wide and small-angle X-ray diffraction (XRD), Raman spectroscopy, Brunauer, Emmett and Teller (BET) surface area analysis, scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS). All the obtained materials exhibits mesoporous structure, crystalline structure indexed in a cubic symmetry, showing a high surface area, a uniform and narrow pore size distribution, spherical morphology typical for the mesoporous materials. The crystalline and mesoporous structures, surface chemistry and stoichiometry for the samples synthesized using ionic and nonionic surfactants have been discussed. [Copyright &y& Elsevier]

Abstract: The wet impregnation of ammonium heptamolybdate onto silica–alumina is used to prepare MoO3/SiO2–Al2O3 heterogeneous metathesis catalysts. The preparation is inspected in details in conjunction with physico-chemical characterization tools with the aim to identify the parameters that dictate the genesis of active and inactive metathesis species. The effects of the MoO3 loading and of the calcination temperature are systematically explored. The samples are characterized by N2-physisorption, ICP-AES, XRD, Raman, 27Al MAS-NMR and XPS and evaluated in the metathesis of propene to butene and ethene. Particular attention is brought to the interaction of the mesoporous silica–alumina support with the active component, to the decomposition of the precursor salt and to the location of the molybdenum oxide phase with respect to the pores of the support. It is shown that the temperature of calcination influences markedly the performances of the catalyst. High temperature treatments are necessary to decompose efficiently the Mo salt precursor. In the metathesis of propylene, the performances are levelling off when the MoO3 loading is increased above ∼8wt.%. This effect is correlated to the build up of MoO3 crystals and of Al2(MoO4)3 at relatively high loading. [Copyright &y& Elsevier]