The modification of M41S materials: addition of metal clusters and nanoparticles

Abstract

The incorporation of various molecular metal clusters, with well defined stoichiometry, into M41S materials has been investigated. The grafting of simple metal clusters, such as [Ru 3 (CO) 12 ] and [PPN] 2 [Fe 4 (CO) 13 ], and the larger, and in one instance, bimetallic, clusters [(dppe) 2 Cu][Cu 6 Fe 4 (CO) 16 ] and [PPh 4 ][Ru 10 (m 6 -C)(m-H)(CO) 24 ] has been achieved. Nanoparticles containing iron and platinum were also anchored on silaceous supports. The proportion of iron to platinum in FePt nanoparticles was adjusted by altering the molar ratios of starting materials.

The use of preformed nanoparticles in the production of heterogeneous catalysts

“…The materials have significant differences not only in chemical composition, but also in surface area and pore structures. The MCM-41 silicate used in this study has been characterized and discussed previously 7,24,25 and is comprised of a well ordered porous system. The alumina alternative, Puralox Table S2) we found that 2.5 hours calcination results in a slight decrease in surface area (185 to 162 m 2 /g) but an increase in the pore diameter (75 to 84 Å), which should lead to greater impregnation of nanoparticles.…”

“…2 (d) and (e)), we can see that particles are found across the surface of the material, however they tend to occur as clusters rather than being fully distributed as in the Fe-MCM system and the previously studied FePt MCM-41 material. 5,7 The clusters of nanoparticles are not large aggregates, rather individual particles that are packed closely together in a region of space, retaining their size. Further analysis of the Fe-puralox material found both areas of well distributed particles across the alumina surface (graphical abstract) and revealed some individual particles distributed across the surface next to a larger cluster (Fig.…”

“…5,7 Reactions were deemed complete when the hexane became colorless. For the iron oxide materials, the solution was still highly coloured after six hours of stirring only becoming clear after being left overnight.…”

“…For comparison, in the FePt system, the solution was fully decoloured in 90 minutes. 7 The composition and structure of support material played no role in altering the assemblage rate as two quite different materials were used yet no real difference was seen in how the particles assembled on the surface or the rate at which it occurs. Since the reactions were carried out in hexane, surface charge is unlikely to play a role in assemblage so we are left with the notion that nanoparticle structure or the coating is perhaps the determining factor in the process of assemblage.…”

“…Despite the development in a number of chemical approaches 4 that give control over particle size and composition, and the subsequent assemblage of these preformed particles onto supports, 5 very few literature examples involving the addition of preformed nanoparticles to support materials exist. 3,6,7 This method is highly advantageous as it allows greater control over what species are assembled onto a support material and it removes the dispersion problems seen with metal clusters in traditional FT catalysts. 8 Further research is required to develop new systems based on the assemblage of preformed particles onto supports so that an assessment of the benefits of these materials can be made.…”