Monohthic technology

Catalytic hydrogenation is typically carried out in slurry reactors, where finely dispersed catalyst particles (<100 (tm) are immersed in a dispersion of gas and liquid. It has, however, been demonstrated that continuous operation is possible, either by using trickle bed [24] or monoHth technologies [37]. Elevated pressures and temperatures are needed to have a high enough reaction rate. On the other hand, too high a temperature impairs the selectivity of the desired product, as has been demonstrated by Kuusisto et al. [23]. An overview of some feasible processes and catalysts is shown in Table 8.1. 

After we identified a new superior washcoat, a monolithic catalyst (HDC-25) was prepared with this washcoat and was tested. The honeycomb monolith with 400 cpsi was used as a support, and powder catalysts were coated on the monohth by Degussa s proprietary washcoating technology. For comparison, oxn existing commercial PTA offgas catalyst (HDC-7) was also tested under identical conditions. The results are shown in Figures 9 and 10, and Table 1. 

Recently, the sol-gel method has become very attractive for materials synthesis because it permits direct fabrication of multicomponent materials in different configurations (monoHths, coatings, and fibers) without powder intermediates [3] or without the use of expensive vacuum technologies [4,5], The diversity with which materials can be obtained, has made the sol-gel method an important synthesis route in several domains of research, including optics, electronics, biomaterials, and semi- and superconductors. 

Wong H. Y., M. Sorel,A C. Biyce,J. H. Marsh, J. M. Arnold (2005) "Monohthically integrated InGaAs-AlGalnAs Mach-zehnder interferometer optical switch using quantum-well intermixing" I hhh Photonics Technology Letters, Vol. 17, No. 4, p>age no. 783-785, April 2005. 

In contrast to ceramic and metallic monoHths developed for automotive exhaust treatment purposes, which nowadays carry chaimels on the microscale and are actually micro-reactors by definition, the micro-reactors discussed in this chapter rather cover plate heat-exchanger technology with chaimels on the microscale. An overview of the fundamentals, practical applications, and production issues of micro-reactors for fuel-processing purposes is provided. 

Allstot, D. J. and Black, W.C. Jr. 1983. Technological design considerations for monohthic MOS switched-capacitor filtering systems. IEEE Proc. 71(967). 

It is likely that cordierite, titanate and zirconate ceramics will record the most rapid rates of growth, due to their uses in environmental systems, medical products, electronic components, and household appUances. A continued expansion in electronic component shipments will provide opportunities for titanate per-ovskites and other ceramics. Nonetheless, cordierite, titanates and other ceramics will undoubtedly benefit from a continued, environmentally driven trend to reduce the amounts of particulates, nitrogen oxides (NO,), and sulfur oxides that are released into the atmosphere. Technological advances in the medical product market will also provide many opportunities, notably for monohthic ceramics such as alumina and zirconia used for femoral balls in hip endoprostheses, as well as biocompatible hydroxyapatite and tricalcium phosphate coatings for the metal stems of hip implants (see also Chapter 10). Likewise, dental ceramics wiU continue to experience high growth rates through 2010. 

A microstructured monolith for autothermal reforming of isooctane was fabricated by Kolb et cd. from stainless steel metal foils, which were sealed to a monohthic stack of plates by laser welding [73]. A rhodium catalyst developed for this specific application was coated by a sol-gel technique onto the metal foils prior to the sealing procedure. The reactor carried a perforated plate in the inlet section to ensure flow equi-partition. At a weight hourly space velocity of 316 L (h gcat). S/C 3.3 and O/C 0.52 ratios, more than 99% conversion of the fuel was achieved. The temperature profile in the reactor was relatively flat. It decreased from 730 °C at the inlet section to 680 °C at the outlet. This was attributed to the higher wall thickness of the plate monolith compared with conventional metallic monolith technology. The reactor was later incorporated into a breadboard fuel processor (see Section 9.5). 

Baek, S.-G., Magda, J. J. Monohthic rheometer plate fabricated using silicon micro-machining technology and containing miniature pressure sensors forNj andN2 measurements./. Rheol. (2003) 47, pp. 1249-1260... 

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