Topic
MCM-41
About: MCM-41 is a research topic. Over the lifetime, 2355 publications have been published within this topic receiving 91416 citations.
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TL;DR: In this paper, a comparative study of silane oxidation, olefin epoxidation, and thianthrene 5-oxide sulfoxidation with the oxidants Ti-β/H 2 O 2, Ti-MCM-41/ t -BuOOH, and Ti-ITQ-2/t -buOOH provides the catalytic reactivity order
50 citations
TL;DR: Nickel ion exchanged MCM-41, MCM 48 and SBA-15 mesostructured materials with a controlled concentration of nickel and acidic sites were prepared, characterized, and successfully used as catalysts in the ethylene oligomerization performed in slurry batch mode as mentioned in this paper.
Abstract: Nickel ion exchanged MCM-41, MCM-48 and SBA-15 mesostructured materials with a controlled concentration of nickel and acidic sites were prepared, characterized, and successfully used as catalysts in the ethylene oligomerization performed in slurry batch mode (T = 150°C, p = 3.5 MPa). Larger pores or a 3D pore system, as well as an equilibrated balance between acid and nickel ion sites were very favorable for the oligomerization process.
50 citations
TL;DR: In this article, a series of zirconium doped MCM-41 silica supported WO x solid acid catalysts, with WO 3 loading ranging from 5 to 25wt, has been prepared by impregnation with ammonium metatungstate.
Abstract: A series of zirconium doped MCM-41 silica supported WO x solid acid catalysts, with WO 3 loading ranging from 5 to 25 wt%, has been prepared by impregnation with ammonium metatungstate. After activation at 700 °C, these catalysts are active in the transesterification of sunflower oil with methanol at 200 °C, with a biodiesel yield higher than 80% after 2.5 h of reaction. The maximum activity (82 wt% of FAME yield) is found for the catalyst with 15 wt% WO 3 loading, which is able to simultaneously catalyze the esterification and transesterification of simulated used oils, with an acidity degree as high as 9.1%. Moreover, this catalytic activity is maintained in the presence of 5 wt% of water and after three cycles of reutilisation, without any treatment of the catalyst.
50 citations
TL;DR: Two chemically orthogonal functionalities are incorporated into mesoporous silica by co-condensation of tetraethoxysilane with two orthogonally functionalized triethoxyalkylsilanes and are used as cooperative catalysts in the Henry reaction.
Abstract: The synthesis of bifunctional mesoporous silica nanoparticles is described. Two chemically orthogonal functionalities are incorporated into mesoporous silica by co-condensation of tetraethoxysilane with two orthogonally functionalized triethoxyalkylsilanes. Post-functionalization is achieved by orthogonal surface chemistry. A thiol-ene reaction, Cu-catalyzed 1,3-dipolar alkyne/azide cycloaddition, and a radical nitroxide exchange reaction are used as orthogonal processes to install two functionalities at the surface that differ in reactivity. Preparation of mesoporous silica nanoparticles bearing acidic and basic sites by this approach is discussed. Particles are analyzed by solid state NMR spectroscopy, elemental analysis, infrared-spectroscopy, and scanning electron microscopy. As a first application, these particles are successfully used as cooperative catalysts in the Henry reaction.
50 citations
TL;DR: In this paper, the local environment of Ti(IV) sites in these materials was studied using diffuse-reflectance UV-Vis, photoluminescence and Raman spectroscopies.
Abstract: Titanium-aluminophosphate and silico-aluminophosphate with chabasite-like structures (TAPO-34 and TAPSO-34) have been hydrothermally synthesised using morpholine as structure-directing agent. The local environment of Ti(IV) sites in these materials was studied using diffuse-reflectance UV-Vis, photoluminescence and Raman spectroscopies. This study, combined with the study of Ti-grafted MCM-41 mesoporous catalyst and a titanosilsesquioxane dimer molecular complex with a well-defined co-ordination of the Ti(IV) centers, revealed that a fraction of Ti(IV) ions are present in tetrahedral co-ordination, consistent with some Ti(IV) ions being incorporated into the aluminophosphate frameworks. However, Raman spectroscopy showed that around 20% of the total amount of the titanium used in the gel synthesis is present in a TiO2-like extra-phase.
50 citations