Microstructured platelets

For this micro reactor version, the microstructured platelets were treated by anodic oxidation to obtain a nano-porous layer and impregnated with precursor solutions in organic solvents to obtain a V205 P205 Ti02 catalyst. 

Microfabrication of the parallel channels was performed by mechanical surface cutting of metal tapes [31]. In the case of aluminum alloys, ground-in monocrystalline diamonds were used [45]. In the case of iron alloys, ceramic micro tools have to be used owing to the incompatibility of diamonds with that material. Such a microstructured platelet stack is provided with top and cover plates, diffusion bonded and connected to suitable fittings for the inlet and withdrawal ducts by electron beam welding (Figure 3.9). 

Figure 2.14 Photograph of a single microstructured platelet (right) [38] (by courtesy of ACS).

Fig. 6.7 Equaling-up for the StarLam mixer series by varying the number of microstructured platelets [27. To have the same volume filled within the recess of the housing, a dummy block with inner channel is placed on top of the platelet stack for...

Fig. 6.8 Segregation index, as defined in Ref [28], for mixing of aqueous solutions in a StarLam300 mixer with a varied number of microstructured platelets, all 100 pm thin [27]. The curves correspond to 25, 50, 75,...

A gas-phase microreactor with an included missing unit is also offered by IMM, especially for the performance of reactions in the explosive regime. It consists of two recesses, each filled with a stack of microstructured platelets for premixing of gases... 

To overcome these medium- to long term substrate degradation issues, the surface of the structured material has to be properly prepared and protected during the phase of assembly and catalyst coating. This feature is so important that, as mentioned before, almost no relevant and detailed long-term studies have been reported yet on the corrosion effects on stainless-steel microstructured platelets. 

Figure 4.1 (a) Coverage ratio as a function of binder content and solid loading, (b) Coverage ratio over the platelet using the reference slurry as a function of the position of the coated channels over a microstructured platelet. 

Figure 4.1a illustrates a complex relationship that was established between two washcoating parameters, the content of binder and of alumina/boehmite (referred to as solid ) added to the slurry and the observed coverage ratio of the microstructured platelet after calcination at 800 ° C and the formation of a y-alumina layer. Figure 4.1b indicates that heterogeneity in surface coverage may also depend on the position of the channels over a given microstructured platelet [37]. 

A hyper-eutectic alloy containing, say, 50% Sb starts to freeze when the temperature reaches the liquidus line (point a in Fig. 20.39). At this temperature pure pro-eutectic Sb nucleates as the temperature continues to fall, more antimony is deposited from the melt, and the composition of the liquid phase moves down the liquidus line to the eutectic point. When this is reached, the remainder of the melt solidifies. The microstructure of alloys of eutectic composition varies somewhat with alloy system, but generally consists of an aggregate of small particles, often platelets, of one of the phases comprising the eutectic in a continuous matrix of the other phase. Finally, the microstructure of the hypereutectic 50% Sb alloy already mentioned... 

The platelets comprise an array of parallel micro channels with microstructured triangular-shaped headers at both ends. In the headers holes form conducts to the external feed fluid supply. Optimization of the shape of the header with respect to flow equalization was the topic of various simulation studies [52, 53]. 

The microstructured plates were made by wet-chemical etching. The platelet stack was bonded by standard welding. The inlet and outlet connectors were also welded. 

Channel carrier a, b Microstructured silicon platelet quartz glass tube Reaction channel a cross-sectional area depth length 0.167 mm 525 pm 20 mm... 

GP 2] [R 2] New microstructured silver platelets have no initial activity for ethylene oxide formation [26, 40]. After treatment with the OAOR process, a small increase in activity was observed. After 1000 h of operation under oxygen conditions, larger amounts of ethylene oxide were produced. 

To achieve the goal of required performance, durability, and cost of plate materials, one approach is improvement of the control of the composition and microstructure of materials, particularly the composite, in the material designing and manufacturing process. For example, in the direction of development of thermoplastics-based composite plate, CEA (Le Ripault Center) and Atofina (Total Group) have jointly worked on an irmovative "microcomposite" material [33]. The small powders of the graphite platelet filler and the PVDF matrix were mixed homogeneously by the dispersion method. The filler and matrix had a certain ratio at the microlevel in the powder according to the optimized properties requirements. The microcomposite powders were thermocompressed into the composite plate. 

The application of this technique to talc-reinforced polypropylene has shown that the microstructure of platelets and the resulting physical properties of the moulded composites are markedly affected [171)]. With two live feeds located at either end of the mould cavity, the talc platelets exhibited strong talc platelet alignment throughout the thickness of the moulding in the direction of the ap-... 

Random copolymers of VF2/F3E when crystallized from the molten state above the Curie temperature show a microstructure in the form of very thin needle-like morphological units which are probably semicrystalline. Figure 5a illustrates the needle-like microstructure of the copolymer 80/20 melt crystallized in the paraelectric phase observed at 140 °C. After codling at room temperature the microstructure of the ferroelectric crystals is such that what appear in the optical microscope as radial fibers are, in fact, stacks of thin platelet-like morphological units (see Fig. 5b). 

Fig. 5. a. Needle-like microstructure of the 80/20 copolymer. Sample cast from dimethyl formamide molten at 180 °C and recrystallized at 140 °C in the paraelectric phase, b. Stacks of thin platelet-like crystals of the same copolymer after cooling the sample at room temperature in the ferroelectric phase. Scale bars, 25 pm... 

A convenient method to produce porous surfaces is the anodic oxidation of aluminum plates. Such microstructured aluminum platelets have been coated by wet impregnation with Pt-, V- and Zr-precursors [35], and tested under catalytic methane combustion conditions. The conversion rate of oxygen followed directly the platinum content in the catalysts. These data were well reproducible even after five different runs. 

The microstructures were realized by a special, advanced turning technique [41]. The platelet stacks were diffusion bonded for sealing and encased in a housing by... 

This interdigital concentric consecutive microstructured mixer is composed of a housing with a cylindrical recess in which a platelet stack is inserted (see Figure 1.108) [130], The device can be operated up to 100 bar and at a temperature of600 °C. 

Figure 1.108 Interdigital concentric consecutive microstructured mixers have the potential for use as chemical production tools, as evidenced by their comparatively large outer dimensions and owing to an internal numbering-up of the micro-structured platelets. Left, front StarLam300 right, back StarLam3000 [130],...

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