Monolithic supports, functionalized

Tab. 8.5 Functional monomers used for surface-grafting of monolithic supports.

The use of a monolithic stirred reactor for carrying out enzyme-catalyzed reactions is presented. Enzyme-loaded monoliths were employed as stirrer blades. The ceramic monoliths were functionalized with conventional carrier materials carbon, chitosan, and polyethylenimine (PEI). The different nature of the carriers with respect to porosity and surface chemistry allows tuning of the support for different enzymes and for use under specific conditions. The model reactions performed in this study demonstrate the benefits of tuning the carrier material to both enzyme and reaction conditions. This is a must to successfully intensify biocatalytic processes. The results show that the monolithic stirrer reactor can be effectively employed in both mass transfer limited and kinetically limited regimes. 

This work describes a new type of monolithic support offering a highly interconnected permanent porosity possessing pendant double bond. This support may provide a better accessibility to active sites and allows the use of a wider range of solvents than classical gel type beads prepared by suspension polymerisation. The free radical addition of functional thiols led to the production of functional supports (acid, ester, alcohol, amine, thiol...). 

The preparation of polymeric monoliths is relatively simple compared with those of the silica rods. A polymerization mixture consisting of monomer, cross-linker, initiator, and porogenic solvent is introduced into a sealed tube. The reaction can be temperature or redox initiated and in the case of transparent molds UV light can also be used to trigger the polymerization. At the end of the reaction the seals are removed and the tubes are attached to a pump, which flushes solvent through the monolith to remove the porogens and the unreacted components. The obtained monolith can be radial or axial compressed to prevent the formation of voids and further functionalized for different chromatographic modes. The majority of current monolithic supports... 

Table 11. Typical value of the key catalyst reaction conditions as a function of the design parameters of the monolithic support for operating conditions relative to a monolith with 62 cells per square centimeter and wall thickness 0.17 mm.

Noble metal catalysts are highly active for the oxidation of carbon monoxide and therefore widely used in the control of automobile emissions. Numerous recent studies on noble metal-based three-way catalysts have revealed characteristics of good thermal stability and poison resistance(l). Incorporation of rare earth oxides as an additive in automotive catalysts has improved the dispersion and stability of precious metals present in the catalyst as active components(2). Monolith-supported noble-metal catalysts have also been developed(3). However, the disadvantages of noble metal catalysts such as relative scarcity, high cost and requirement of strict air/fuel ratio in three-way function have prompted attention to be focused on the development of non-noble metal alternatives. 

Figure 7.9 Variation of bacteria coverage density (number of cells per iOO square pm) as a function of distance from the micro-reactor inlet. The intercept of the dashed line indicates the optimum thickness of the micro-reactor monolithic support...

The latest addition to the family of oligonucleotide separators is the DNA-Swift SAX-IS, which combines a pressure and chemically stable monolithic support coated with functionalized nanobeads. These nanobeads with quaternary ammonium functional groups, optimized for oligonucleotide separations, are similar to those of the DNAPac columns and contribute to the column s high... 

The column itself can be produced as a single open channel or as a branched system of channels starting from one microchannel and ending in another microchannel. The latter type is often named as COMOSS (collocated monolith support structure). With some of the materials mentioned, the channels can serve as stationary phase itself or can be functionalized by coating, packing, or incolumn polymerization with appropriate chromatographic phases. 

Scheme 11.8 Loading of the functional monolithic supports with Pd-based nanoparticles.

Scheme 26 Postsynthesis functionalization of electron-beam curing-derived monolithic supports via ROMP (IMesH2=1,3-dimesitylimidazolin-2-...

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