Mesoporous support

An explanation for this increase in selectivity with the addition of aluminum could be related to the better dispersion of iron metallic clusters, which could be anchored to the acidic sites on the mesoporous support, as observed by Lim et al [13] for bimetallic systems in MCM41. 

Mesoporous supports have been studied in ligand-free rhodium-catalysed hydroformylation aiming at the stabilisation of specific catalytic species to induce... 

R. Raja, J. M. Thomas, M. D. Jones, B. F. G. Johnson and D. E. W. Vaughan, Constraining Asymmetric Organometallic Catalysts within Mesoporous Supports Boosts Their Enantioselectivity, J. Am. Chem. Soc., 2003, 125, 14982. 

Tabakova, Idakiev, Andreeva, and coworkers—Zr a highly efficient support for supported, well-dispersed Au textural effects and mesoporous support preparation. 

It has been previously reported [21, 22] that metal colloids are formed by radiochemical reactions in water/alcohol solutions, in which the reduction of metal salts takes place by solvated electrons and free radicals produced under UV or y-ray irradiation. Ichikawa et al. have applied this photoreduction method to the surface-mediated reaction of metallic ions and succeeded in synthesizing metal/aUoy nanowires in the constrained cavities of mesoporous supports such as FSM-16 and MCM-41 [18-20, 23-25]. The adsorbed water and alcohol work not only as solvents in the nanoscale silica void space but also as a source of reducing species for metallic ions to metals under UV-vis and y-ray [11, 18, 19] irradiation. The results indicate the dense formation of Pt nanowires inside the charmels of mesoporous supports, such as FSM-16, which act as the templates. In fact, no any Pt wire is observed on the external surface of FSM-16 or amorphous silica surface. Short wires, 10 nm long, are also observed as a minor species in the samples in the initial stage of UV and y-ray irradiation. 

Extraction of nanowires from mesoporous supports is important and desirable for their application as a building block for electronic devices and catalyst preparation. In addition, more detailed characterization of metal/alloy nanowires is available by their extraction from the sihca templates. Isolation of the Pt nanowires from mesoporous templates has also been tried by dissolving FSM-16 and HMM-1 with aqueous HF or NaOH solution, but the nanowires were readily decomposed into Pt aggregates. However, the Pt nanowires were successfully extracted as their original forms from the sihca templates using HF and [NBu4]Cl as a surfactant in a benzene/ethanol solution. It is reasonably implied that the extracted wires are... 

High Diffusivity Low Viscosity Figure 15.21 Proposed mechanism of PtRh nanoparticles highly dispersed in HMM-1, which is prepared by H2 reduction of the PtRh salt-impregnated in FSM-16 or HMM-1 after the SCCO2 treatment, while the larger Rh and Pt particles are formed on the external surface of mesoporous supports by the conventional method. 

T0588 Pacific Northwest National Laboratory, Self-Assembled Mesoporous Support (SAMMS) Technology... 

T0554 New Mexico Institute of Mining and Technology, Surfactant-Modified Zeolite T0586 Pacific Northwest National Laboratory, In Situ Redox Manipulation T0588 Pacific Northwest National Laboratory, Self-Assembled Mesoporous Support (SAMMS) Technology... 

Self-Assembled Monolayers on Mesoporous Supports (SAMMS)Technology... 

Pacific Northwest National Laboratory (PNNL) is researching the use of self-assembled monolayers on mesoporous supports (SAMMS) technology for the removal of metals and radionuclides from liquid and gaseous hazardous wastes. SAMMS combines two technologies—mesoporous ceramic material and functionalized monolayers. The ceramic material has pores that increase its surface area. This ceramic material is coated with functionalized monolayers that form stable, covalent bonds with the contaminants. 

II), on a mesoporous support having a hexagonal unit cell. The catalyst was used to prepare 5-norbomene and cyclooctadiene copolymers by ring-opening metathesis polymerization. 

Allows a better dispersion of molybdenum trioxide from the external surface of the mesoporous support into its internal nanochannels. The active sites (possibly pairs of neighboring molybdenum cations) thus increases. As the result of better dispersion, the reduced molybdenum oxide species formed during the course of reaction through its entire surfaces and thus lowers the possibility of sintering in a reduced environment. Here, we see that the deactivation rate is the highest in Mo/Si02 catalyst due to the lowest surface area. 

These studies established that M41S type material is potentially very useful as a support material for energy/environmental catalysts. However, long term hydrothermal stability of the mesoporous support materials should be evaluated. In addition, forming process of the mesoporous powder need to be developed for pressure drop consideration. 

---