Microporous and mesoporous silica

Au/SBA-15 prepared by anion adsorption onto SBA-15 functionalised by cationic groups also had large gold particles ( 8 nm) and low activity, 

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The Surface Hydroxyl Croups of Microporous and Mesoporous Silica-Aluminas (SAs)... 

P-09 - Controlled synthesis of microporous and mesoporous silica-based molecular sieves in the presence of dodecyidimethylbenzylammonium chloride... 

In general, most of doped or nanosized metal sulfide solid solutions could be synthesized by soft chemistry routes however, their low surface areas seriously limit the enhancements in activity. The preparation of high surface area samples with mesoporous stmctures and exposed surface sites is still a great challenge and highly desired [161]. At this end, research efforts should be directed at constructing 2D nanosheets and nanoporous structures of metal sulfide solid solutions [158,162-164]. In addition, the surface areas of metal sulfide solid solutions can be enhanced by loading them into the porous materials such as microporous and mesoporous silicas [165-167]. 

Ryu SY, Balcerski W, Lee TK, Hoffmann MR (2007) Photocatalytic production of hydrogen from water with visible light using hybrid catalysts of CdS attached to microporous and mesoporous silicas. J Phys Chem C 111 18195-18203... 

Another example is CdS particle-doped microporous and mesoporous silicas. These microporous and mesoporous silicas are efficient and stable catalysts that are able to produce H2 from water/ethanol solutions under visible-light irradiation [98]. 

Hess C, Wild U, Schlogl R. The mechanism for the controlled synthesis of highly dispersed vanadia supported on silica SBA-15. Microporous and Mesoporous Materials. 2006 95(l-3) 339-349. 

Akira T., Takayuki A.and Masakazu I., Non-silica-based mesostructured material. 2 Synthesis of hexagonal superstructure consisting of ll-tungstophosphate anions and dodecyltrimethylammonium cations, Microporous and Mesoporous Materials 21 (1998) pp. 387-393. 

Recently microporous and mesoporous materials were found to be particularly suitable for a new type of applications in the mechanical field. This paper reports experimental features about the dissipative forced intrusion of water in highly hydrophobic mesoporous materials this phenomenon can be used to develop a new type of dampers and/or actuators. Silica-based materials behavior was investigated. Among them, MCM-41 exhibits original and interesting properties towards the potential developments of dampers and appears to be of great interest for the comprehension of energy dissipation mechanisms. 

The micropore volume, mesopore volume and the surface area of the mesopores can be calculated from the isotherms. The results of these calculations are also summarized in Table 1. It is known that well prepared MCM-41 material is free of any micropore. The mesoporous silica obtained from NPs, on the other hand, do show small but noticeable micropore volume. The larger mesopore size and higher mesopore volume compared to MCM-41 confirm that obtained mesoporous silica has it unique structure. 

Okuhara, T., Chen, X. Ritter-type reactions catalyzed by high-silica MFI zeolites. Microporous and Mesoporous Materials 2001,48, 293-299. 

H.M. Kao, Y.W. Liao, C.C. Ting, Synthesis of cubic mesoporous silica SBA-1 with bulky headgroup surfactant cetyltripropylammonium bromide. Microporous and Mesoporous Materials, 2007, 98, 80-88. 

The microporous alumino-silicate zeolites (Types A, X, and mordenite are frequently used) provide a variety of pore openings (3-10 A), cavity and channel sizes, and framework Si/Al ratios. They are also available in various cationic exchanged forms (Na, K, Li, Ag, Ca, Ba, Mg), which govern their pore openings and cationic adsorption site polarities. They are highly hydrophilic materials and must be dehydrated before use. The amorphous adsorbents contain an intricate network of micropores and mesopores of various shapes and sizes. The pore size distribution may vary over a wide range. The activated carbons and the polymeric sorbents are relatively hydrophobic in nature. The silica and alumina gels are more hydrophilic (less than zeolites) and they must also be dehydrated before use. 

The regeneration of supercritical carbon dioxide from a mixture containing caffeine by microporous MFI zeolite and mesoporous silica membranes supported on alumina was studied. The experimental data show that a caffeine rejection higher than 90% or 70% and a permeation flux of supercritical carbon dioxide more than 0.05 or 0.07 mol/m /s could be obtained at 10.5 MPa. 

Mesoporous silicas can possess intercage windows within the microporous region, but their stability and acid strength are low compared to those of zeolites. One current approach to this particular problem is the use of partially crystallised zeolite nuclei as starting materials in the synthesis of mesoporous solids, in an attempt to prepare a solid with structural features of both microporous and mesoporous solids. Such solids are said to possess hierarchical porosity, and are discussed further in Chapter 10. 

Fridrikhsberg D. A. (1986) A Course in Colloid Chemistry. Mir Publishers, Moscow Resnick R., Halliday D., Walker J. Fundamentals of Physics, 6th Edition, John Wiley Sons (2001) Nadargi D. Y., Latthe S. S., Hirashima H., A. Venkateswara Rao, Studies m rheological properties of methyltriethoxysilane (MTES) based flexible superhydrophobic silica aerogels, J. Microporous and Mesoporous Mat. 117, 617-626 (2009)... 

Nadargi D Y, Latthe S S, Hirashima H, Rao A V (2009) Studies on rheological properties of methyltriethox-ysilane (MTES) based flexible superhydrophobic silica aerogels. Microporous and Mesoporous Materials 117 617-626... 

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