Ceramic foams

The laboratory prototype of the Dinex electrochemically promoted catalyst unit is shown in Figure 12.12 and the assembled unit schematically in Fig. 12.13. It consists (Fig. 12.14) of a tubular bundle porous (ceramic foam) structure made of CeOa-GcfeOj (CGO) which is an O2" conductor with ionic conductivity significantly higher than YSZ at temperatures below 500°C... 

FIGURE 14.46 An aerogel is a ceramic foam. Its low density and low thermal conductivity, combined with great strength, make it an ideal insulating material. Here a thin piece protects three wax crayons from the heat of a fiame. Aerogels were used to insulate the Mars Rover. 

New developments in the field of ceramic foam monoliths could also potentially provide new catalytic process technology for the conversion of methane into synthesis gas. For example, workers at Minnesota University [9] have achieved high synthesis gas yields at both high temperatures and space velocities using rhodium supported on a ceramic foam. 

One or more 12.7-centimeter (5-inch) OD porous layers can be installed in the rig at any axial location in the three sections. Each layer could be positioned using one custom-made retaining ring behind. In all of the tests reported here the porous material was a SiC ceramic foam supplied by Hi-Tech Ceramics of Alfred, New York. All the ceramic foams were 12.7 cm (5 in.) in diameter with varying thickness from 1.3 cm (0.5 in.) to 2.5 cm (1 in.). Two different pore sizes were tested, including 8 ppcm (20 ppi) and 18 ppcm (45 ppi). According to the manufacturer the porosity of the ceramic foams was about 80%. 

Another process involves the fluid mechanics. The large-scale mixing due to swirl-induced recirculation and smaller scale turbulence mixing could be reduced by the inserts. And, it has been reported that the magnitudes of the turbulence intensities are lower in the small-pore ceramic foam [2]. Chemical reactions of the exit flows could be suppressed due to the reduced turbulence mixing strength. This effect could be another cause for the lower temperatures at 1.8 2.2 pipe... 

Weiland et al observed that a small amount of Pt metal present in the Rh-based catalyst could significantly improve the catalyst activity for ATR of gasoline range fuels. They claimed that the role of Pt is to enhance oxidation activity, whereas Rh provides high SR activity. The Rh-Pt/alumina catalyst used in the study was supported on monolithic honeycombs and had a Rh to Pt ratio of 3-10 by weight. The geometry (metal monolith, ceramic monolith, or ceramic foam) of the support did not affect the product composition. ... 

Foams have a large variety of applications. Solid foams are widely used as insulating materials. Due to the presence of air bubbles they have a low thermal conductivity. Polyurethane foams and Styrofoam are examples. Styrofoam is also used as a packing material. The light weight of polymer foams makes them attractive as filling materials to stabilize otherwise hollow structures. A natural solid foam is pumice stone. Metal foams are used in the automotive and aerospace industry as light and stable materials [567], Ceramic foams are developed for electronic applications as piezoelectric transducers and low dielectric constant substrates [568],... 

Rotors filled with ceramic foam instead of perforated cylinders have been tested for liquid extraction of trace contaminants from water (23). The test solution... 

Some of these modules were fabricated in solid ceramic materials allowing chemical reactions with highly corrosive reactants or products or even at very high temperatures. Also special ceramic foams were developed which can be used as a catalyst carrier. 

Ceramic foams can be inserted into microstructure devices made from metals and polymers to enhance the surface area, act as catalyst supports or even work as heaters. Details of these processes can be found in Refs [29-42]. 

Twigg MV, Richardson JT. Fundamentals and applications of structured ceramic foam catalysts. Industrial Engineering Chemistry Research. 2007 46(12) 4166-4177. 

The lowest balance point temperature was measured with a combination of platinum and cerium fuel additives with a platinum treated ceramic foam filter placed... 

With the system studied, NO, reduction up to 20% was measured. This reduction could possibly be optimised using the right filter geometry, for example with a ceramic foam. 

In this highly exothermic reaction, kinetic control is a function of the catalyst characteristics and surface temperature, and the mass transport control and boundary layer thickness is based on the catalyst bed geometry and flow velocity. Both the gauze and ceramic foam have tortuous flow paths, but the extruded cordierite monolith has microchan-... 

We designate as composite (combined) such systems as are formed by combination of growth and addition systems. As a rule, such systems are produced both by the addition of individual elements and through growth of the individual elements (e.g. pore formation or foaming). Composite systems are, for exemple, ceramics, foam glass, fabrics, Gouch filters, membrane filters, most construction materials, metallic or polymeric cakes, etc. 

Seijger GBF, Oudshoom OL, van Kooten WEJ, Jansen JC, van Bekkum H, van den Bleek CM, and CaUs HPA. In situ s3fnthesis of binderless ZSM-5 zeolitic coatings on ceramic foam supports. Micropor Mesopor Mater 2000 39 195-204. 

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