Porous supports preparation

The silicalite-alumina membrane was prepared after adding a solution containing the silicalite precursor (i e silica + template) to the above-mentioned porous tube (hereafter called support) and a specific hydrothermal treatment performed [8], under the chosen conditions no material is formed in the absence of the porous support. The tube is then calcined at 673 K for removing the template. 

Haas-Santo, K., Eichtner, M., Schubert, K., Preparation of microstructure compatible porous supports by sol-gel synthesis for catalyst coatings, Appl. Catal. A 220 (2001) 79-92. 

Of particular interest are membranes prepared of an inert porous support carrying natural or artificial lipids. These coatings may comprise a single component, such as isopropylmyristate or dodecanol [99, 106], or mixtures of comparable composition as the stratum corneum intercellular bilayer [107, 108], Usually, synthetic lipids are used, due to an elaborate isolation procedure for stratum corneum lipids, with limited yield and the necessity of separation of triglycerides, originating from subcutaneous fatty tissue or skin care products [109],... 

Numerous efforfs have been made to improve existing fhin-film catalysts in order to prepare a CL with low Pt loading and high Pt utilization without sacrificing electiode performance. In fhin-film CL fabrication, fhe most common method is to prepare catalyst ink by mixing the Pt/C agglomerates with a solubilized polymer electrolyte such as Nation ionomer and then to apply this ink on a porous support or membrane using various methods. In this case, the CL always contains some inactive catalyst sites not available for fuel cell reactions because the electrochemical reaction is located only at the interface between the polymer electrolyte and the Pt catalyst where there is reactant access. 

Nonpermanent means separation layer is formed during the preparation process in-situ on a porous support... 

Powders of these materials are first prepared and then formed into spherical pellets in a ball mill or into cylindrical pellets by extruding a paste. A catalyticaUy active component such as a noble metal or a multivalent oxide is then frequently added to one of these porous supports by depositing ions from salt solution and heating to dry and decompose the salt. We are then interested not in the total surface area of the pellet but the area of the catalyticaUy active component. 

Figure 9.2 A schematic presentation of different types of enzyme preparations used in non conventional media, a enzyme powder, b enzyme crystals c enzyme on a porous support d covalently modified enzyme dissolved in the solvent e enzyme solubilised by surfactant ...

Impregnated catalysts are prepared by impregnating a metal salt on a porous support. The metal loading in the finished catalyst is typically 1-5 %. 

Catalysts are prepared by impregnation by spraying a solution of a metal salt onto pellets of a porous support until incipient wetness. The pellets are then dried and calcined to transform the metal into insoluble form. 

When entrapment methods are being used for heterogenization, the size of the metal complex is more important than the specific adsorptive interaction. There are two different preparation strategies. The first is based on building up catalysts in well-defined cages of porous supports. This approach is also called the ship in a bottle method [29]. The other approach is to build up a polymer network around a preformed catalyst. 

Gas separation membranes may be prepared in a continuous manner by passing a porous support, which may be backed by a fabric through a solution of TPX dissolved in an organic solvent, such as hexane. The support member is passed through the solution... 

A few studies have reported the embedding of an MIP film between two membranes as a strategy for the construction of composite membranes. For example, a metal ion-selective membrane composed of a Zn(II)-imprinted film between two layers of a porous support material was reported [253]. The imprinted membrane was prepared by surface water-in-oil emulsion polymerisation of divinylbenzene as polymer matrix with 1,12-dodecanediol-0,0 -diphenylphosphonic acid as functional host molecule for Zn(II) binding in the presence of acrylonitrile-butadiene rubber as reinforcing material and L-glutamic acid dioleylester ribitol as emulsion stabiliser. By using the acrylonitrile-butadiene rubber in the polymer matrix and the porous support PTFE, an improvement of the flexibility and the mechanical strength has been obtained for this membrane. 

Analogous membranes have been prepared from poly(L-glutamic acid) containing about 14 mol % azobenzene-sulfonate groups in the side chains (Scheme 3, Structure IV). 25 109 The polypeptide was adsorbed onto a porous support and the hydro-... 

By far the majority of polymeric membranes, including UF membranes and porous supports for RO, NF or PV composite membranes, are produced via phase separation. The TIPS process is typically used to prepare membranes with a macroporous barrier, that is, for MF, or as support for liquid membranes and as gas-liquid contactors. In technical manufacturing, the NIPS process is most frequently applied, and membranes with anisotropic cross-section are obtained. Often,... 

Composite membranes combine two or more different materials with different characteristics to obtain optimal membrane performance. Basically, the preparation involves (i) preparation of porous support that is usually made by a phase-separation process (cf. Section 2.4.2), and (ii) deposition of a selective barrier layer on this porous... 

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