Mesoporous interlayer

Figure 3 Schematic view of zeolite crystals, embedded within a mesoporous interlayer...

The hydroamination of alkenes has been performed in the presence of heterogeneous acidic catalysts such as zeolites, amorphous aluminosilicates, phosphates, mesoporous oxides, pillared interlayered clays (PILCs), amorphous oxides, acid-treated sheet silicates or NafioN-H resins. They can be used either under batch conditions or in continuous operation at high temperature (above 200°C) under high pressure (above 100 bar). 

As discussed in the previous section, one of the major DSSC bottlenecks is the charge transport across the electrode network. Recently, different groups have demonstrated that implementation of nanocarbons in the form of (i) interlayers on the bottom and/or on top of the mesoporous film, and (ii) dopants inside the electrode network, is a very powerful strategy to overcome this issue. In this section, the most relevant aspects are outlined. 

The Langmuir-Blodgett method has been used to prepare hybrid films of an anionic Ru(ll) cyanide polypyridyl complex with LDHs [170]. An LDH film was formed on mica owing to the interaction between LDHs particles and the Ru(ll) cyanide polypyridyl complex that was pre-dispersed on the surface of mica. Water-in-oU emulsions composed of octane, water and sodium dodecyl sulfate (SDS) have been used to synthesize Mg/Al LDHs with carbonate as the interlayer anion [171] by constant pH or variable pH methods. A floccule or fiber-like LDH material that possesses similar chemical composition and properties to that synthesized using a conventional variable pH method was obtained. The resulting LDH shows high surface area and a narrow distribution of mesopores. 

Fig. 4. Specific surface areas for several mesoporous materials as a function of interlayer silicate content.

Mesoporous materials in which rearranged interlayer anisotropic silicates act as long pillars were produced as the heat-treated products of organophilic hectorites. 

Burning off the template leaves behind mesopores in the structure [19]. In the use of OTMA, the order of addition is very important. If OTMA is added first before adding sol oxides, OTMA occupies the interlayer spaces and prohibits the intercalation of sol particles, since the organic cations are exchanged more selectively than sol oxides. This does not lead to increase in porosity. By using the sol oxides first, a porous structure with a BET surface area exceeding 500 m /g and a porosity of about 1.0 ml/g was obtained. 

Porosity is divided by IUPAC (Rouquerol et al. 1994), based on pore size, into the following groups macropores (>50 nm), mesopores (2-50 nm), and micropores (<2 nm). Microporosity may then be subdivided into three subsequent categories supermicropores (1.4-2.0 nm), micropores (0.5-1.4 nm), and ultramicropores (<0.5 nm). Both mineral and organic soil components have pores with different diameter. The holes and channels in the polymer chain of humic substances as well as the interlayer space of the layered mineral have an important role in determining the specific surface area. The size of the interlayer space of layered minerals in a dry state is a few tenths of nanometers, so they are considered as micropores. 

A nanomaterial can be loosely defined to be any material containing heterogeneity at the nanoscale in one or more dimensions. In the broadest sense, then, the following are nanomaterials phase-separated glasses or crystals with domains in the nanoregime, zeolites and mesoporous materials with pores of nanometer dimensions, clays with nanometer sized alternations of aluminosilicate layers and interlayer hydrated cations, and nanoscale leach layers at the mineral-water interface. 

G. Alberti, U. Costantiono, F. Marmottoni, R. Vivani, and P. Zappelli, Preparation of a Covalently Pillared a-Zirconium Phosphite-diphosphonate with a High Degree of Interlayer Porosity. Microporous Mesoporous Mater., 1998, 21, 297-304. 

We report here preliminary results of the physicochemical characterization of a composite material obtained by combining the cethyltrimethylammonium cations clay insertion procedure with the room temperature synthesis of mesoporous materials inside of clay layers. The Romanian bentonite, containing 64% montmorillonite was used. The organic cations are incorporated within the interlayer region of the clay, serving to prop of>en the layers and to allow incorporation of the silicon source for MCM-4I synthesis. The obtained materials display a high thermal stability and molecular sieve properties. 

The basical theories, equipments, measurement practices, analysis procedures and many results obtained by gas adsorption have been reviewed in different publications. For macropores, mercury porosimetry has been frequently applied. Identification of intrinsic pores, the interlayer space between hexagonal carbon layers in the case of carbon materials, can be carried out by X-ray dififaction (XRD). Recently, direct observation of extrinsic pores on the surface of carbon materials has been reported using microscopy techniques coupled with image processing techniques, namely scarming tunneling microscopy (STM) and atomic force microscopy (AFM) and transmission electron microscopy (TEM) for micropores and mesopores, and scanning electron microscopy (SEM) and optical microscopy for macropores [1-3],... 

Huang A, Wang N, Caro J. Synthesis of multi-layer zeohte LTA membranes with enhanced gas separation performance by using 3-aminopropyltriethoxysilane as interlayer. Micropor Mesopor Mater, 2012 164 294-301. 

In contrast to sulfonated materials, novel metal oxide catalysts are also apphcable for sugar hydrolysis. Water-tolerant sohd adds, such as layered HNbMoOg [55, 151], HTaMoOg [54], mesoporous Nb-W oxides [61], andTa-W oxides [62], showed high activity for ceUobiose hydrolysis, a unit of cellulose. The high performance of layered oxides is attributed to facile intercalation of ceUobiose into the interlayer... 

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