Microreactors properties

Hence in this chapter some general issues will be discussed that can be important when choosing a microreactor. Common aspects of microreactor properties will be shown to give hints as to which of them may be important for a particular problem and which not. 

Especially the favorable mass transfer of micro reactors is seen to be advantageous for the oxidation of benzyl alcohol [58]. As one key to this property, the setting and knowledge on flow patterns are mentioned. Owing to the special type of microreactor used, mixing in a mini trickle bed (gas/liquid flows over a packed particle bed) and creation of large specific interfaces are special aspects of the reactor concept. In addition, temperature can be controlled easily and heat transfer is large, as the whole micro-reactor construction acts as a heat sink. 

For application in flow reactors the nanocarbons need to be immobilized to ensure ideal flow conditions and to prevent material discharge. Similar to activated carbon, the material can be pelletized or extruded into millimeter-sized mechanically stable and abrasion-resistant particles. Such a material based on CNTs or CNFs is already commercially available [17]. Adversely, besides a substantial loss of macroporosity, the use of an (organic) binder is often required. This material inevitably leaves an amorphous carbon overlayer on the outer nanocarbon surface after calcination, which can block the intended nanocarbon surface properties from being fully exploited. Here, the more elegant strategy is the growth of nanocarbon structures on a mechanically stable porous support such as carbon felt [15] or directly within the channels of a microreactor [14,18] (Fig. 15.3(a),(b)), which could find application in the continuous production of fine chemicals. Pre-shaped bodies and surfaces can be... 

Catalytic Combustion Properties of M-substituted Hexaaluminates - Most of the catalytic studies performed over hexaaluminate materials deal with the combustion of CH4 as the main component of natural gas, i.e., the typical fuel of gas turbines. Arai and co-workers were the first to investigate the CH4 combustion activity of BaMAlnOjg with M=Cr, Mn, Fe, Co, Ni prepared via the alkoxide route.5 Activity tests were performed over powder catalysts using a conventional quartz microreactor fed with a diluted CH4-air mixture (1% CH4) at high-space velocity (GHSV=48000 h 1). The results are summarized in Table 3 in terms of T10% (i.e., the temperature required to achieve 10% conversion). 

In this work the reactions of ammonia with chlorobenzene and benz-aldehyde over a series of metal ion-exchanged zeolites were investigated by the microreactor method, and attempts were made to relate the catalytic activity of the zeolites to properties of metal cations. Ammonia was a reactant and a poison for acidic sites. 

A series of Chromia-Alumina aerogel catalysts containing different contents of chromium was prepared by autoclave method. The specific areas of the catalysis were measured with Ng at 77°K according to the BET method. Their structural properties were determined from the X ray diffraction patterns recorded on a philips diffractometer PW 1050/70. EPR measurements were performed with a 8ruker ZOO TT spectrometer at 77°K operating in X band. DPPH was used as the g value standard. Kinetic data were obtained in dynamic pyrex microreactor operating at atmospheric pressure as described elsewhere (ref. 3). 

Microemulsion is used as a special microreactor to limit the nano-sized particles growth. The shape of the microreactor depends on reaction conditions [9]. This method increases the homogeneity of the chemical composition at nano-level and facilitates the preparation of nano-particles with comparatively equal sizes [11]. The specific properties of the nano-particles make them suitable for microelectronics, ceramics, catalysis, medicine, cosmetics, as piezoelectric materials, conductors, etc. 

Since it will take several years to realize such an integral software toolbox, individual approaches with separate steps have to be applied to meet gradually the requirements of microreactor design. Standard software for computational fluid dynamics is directly applicable in this context, and there are also powerful software tools for the simulation of special steps in microfabrication processes. However, there has been rather little experience with materials for microreactors, optimization of microreactor design, and, in particular, the treatment of interdependent effects. Consequently, a profound knowledge of the basic properties and phenomena of microreaction technology just described is absolutely essential for the successful design of microreaction devices. 

Besides using microreactor devices for efficient screening of biocatalysts, these can also be applied for enzymatic synthesis. Biocatalyzed reactions have recently received much attention because of the efficiency and selectivity that enzymes have to offer, combined with their ability to act under mild conditions [422,423]. Microreactors offer in this respect the advantage that enzymes can be more optimally used as a result ofthe higher mass-transfer properties of microchannels and the high surface-... 

Related product properties are improved, for example, optical properties such as the glossiness and transparency (see Table 5.1). There are no negative consequences for dye manufacturing with the new microreactor made crystals, as the tinctorial power is the same as for conventional synthesis. Tinctorial power is a measure for the adhesion of the pigment to wool stuff or similar material. The intensification in coloration properties means that the same amount of material can be treated now with less amounts of the Yellow 12 azo pigment that reduces materials costs and increases the profitability of the pigment manufacture. 

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