A-cordierite

Figure 11 Yields of H2, CO, CO2, and CH4 from reforming of benchmark gasoline fuel catalyzed by Rh- or Pt-CGO supported on a cordierite monolith (Conditions OjC = 0.88, SIC = 1.6, GHSV = 9,000...

To delay crystallization, an additional element can be added, e.g. yttrium or magnesium76. Thus, Laine and coworkers80 have shown that ammonolysis of a cordierite (2Mg0 2Al203 5Si02) precursor system provides access to MgSiAlON materials. The development of a cordierite precursor is described below in the sections on silicate precursors. 

Germani et al. [82] compared the performance of their catalyst coating developed for water-gas shift in a micro structured reactor with that of the same catalyst coated on a cordierite monolith under identical reaction conditions. Higher conversion was achieved in the micro channels at same modified residence time under all experimental conditions applied. Figure 2.88 shows the CO conversion vs. a modified residence time (catalyst weight/flow of carbon monoxide) measured at various reaction temperatures. 

For deNOxing lean exhaust gas within a broad temperature range, methods using multi-stage catalysts active in different temperature domains have been claimed, e.g. by Toyota and Tosoh Corporation (67) for the combination of Co-Ba/H-MFI and Cu/H-MFI on a cordierite honeycomb and by Mazda Motor... 

Ham et al. (99) have studied the effect of S02 in the temperature range 523-723K. Below 573 K a decrease of activity by 60% at 523 K and 20% at 573 K occurs, while above 573 K no inhibition was observed. During the tests at low temperature with S02, accumulation of ammonium sulfate and/or ammonium bisulfate occurs and may cause severe blocking. At higher temperatures these salts decompose and this may explain the absence of inhibition. Complete regeneration of deactivated catalysts can be achieved by heat treatment at 773 K. Over Cu-H-MOR bound with silica and deposited on a cordierite honeycomb, only 12% decrease of NO conversion was observed at 673 K after 350 h passivation in presence of 200... 

FIGURE 28 Metal concentration profiles along the length of a monolith for deposition precipitation by use of urea decomposition with nickel nitrate on a cordierite monolith. Metal deposited on a 25-cm-long, 1-cm-diameter, 400 cpsi monolith. Profiles were determined by X-ray fluorescence spectroscopy of finely ground 2.5-cm long sections of the monolith. 

Table 3 shows the textural characteristics of three carbon monoliths, two of which were produced by dipcoating a cordierite monolith with a solution of sucrose or PFA and one of which was produced by a CVD process resulting in a CNF coating. These are referred to as Cord-SUC, Cord-PFA, and Cord-CNF, respectively. From a texture analysis, it was concluded that the sucrose-derived carbon is highly porous, with pore diameters in a favorable range (t)q5ically, 11 nm). The PFA-derived carbon was microporous and, as a consequence, not suitable for adsorption of large species, such as enzymes. 

Avvakumov EG., Gusev A.A., Cordierite as a Prospective Ceramic Material. Novosibirsk SO RAN, 1999. 

The use of catalytic converters to reduce the amount of unbumed hydrocarbons in exhaust gases is an additional example of the use of metals. Reactions of these unbumed hydrocarbons in the atmosphere are described later, in the section on photochemical smog. The catalyst currently used is a cordierite or alumina support treated with an AI2O3 wash coat containing rare earth oxides and 0.10% to 0.15% Pt, Pd, and/or Rh, which catalyzes the combustion of hydrocarbons in the exhaust gases to carbon dioxide and water. Platinum,... 

Figure 11 Temperature profiles of the combustion front during burner regeneration of a cordierite filter with a bypass system. (Courtesy of the Society of Automotive Engineers.)...

EDX mapping of the cross section of a cordierite (Mg2AUSi50i8) monolith coated... 

FIGURE 10.27 Left cross section of a mordenite film prepared on a cordierite monolith. Right detail of the film. 

FIGURE 6.18 Linear scan voltammograms for (a) cobalt spinel, (b) a-cordierite, (c) P-cordierite, and (d) CoO, attached to paraffin-impregnated graphite electrodes immersed into 1.0 M HCl. Potential scan rate 20 mV/sec. 

FIGURE 6.19 Deconvoluted linear scan voltammograms for paraffin-impregnated graphite electrodes modified with different cohalt cordierites (a) cordierite glass, (h) p-cordicrile, and (c) a-cordierite, immersed into 2.0 mM sorbitol plus 0.10 M NaOH. Potential scan rate 20 mV/sec. 

Montreuil and Shelef [81] studied the SCR reaction over ZSM-5/AI2O3 supported on a cordierite monolithic substrate. Various oxygenated hydrocarbons, such as methanol, ethanol, propanol, acetaldehyde, acetone, methyl ethyl ketone, and 1,4-dioxane were used as reductant at 755 K [81]. The reaction extent with the various organic compounds was compared with that obtained when using propene as reductant. Propene was the superior reductant. Methanol as a reductant showed a very low NO conversion, whereas propanol showed the highest activity, albeit lower than that of propene. Upon adding oxygen to the feed the difference between propanol and propene vanishes. 

Metal based fuel additives, such as Ce [3], Cu [4, 5], Fe [6], and Mn [7, 8, 9] have been studied for use in combination with a particulate filter. In general, a wall flow monolith is applied as a particulate filter in this kind of operations. In this study the performance of a copper fuel additive in combination with a cordierite wall flow monolithic filter is compared with that of copper coated wall flow monolithic filters. Furthermore, the performance of a silicon carbide wall flow monolithic filter was compared with that of a cordierite one. 

Sabioni ACS, Huntz AM, Phihbert J, Lesage B (1992) Relation between the oxidation growth rate of chromia scales and self-diffusion in Cr203. J Mater Sci 27 4782-4790 Sabioni ACS, Zanotto E, Millot F, Fuller H (1998) Oxygen self-diffusion in a cordierite glass. J Non-Crystalline Solids 242 177-182... 

Figure 3 shows the temperature progression from the CFD model for a eylindrical reactor containing a cordierite monolith that is heated to 700°C. This result suggests that the reformer monolith can attain its desired temperature in 30 seeonds if a hot gas at 730°C is fed at a spaee veloeity of 45,000 per hour (h" ), assuming no heat losses. Similar start-up Figure 3. Initial Temperature Progression in Reformer scenarios can be obtained for the other zones.

As shown in Figure 1, Rh- or Ni-CGO supported on a cordierite monolith were observed to be more active than Pt-CGO supported on a cordierite monolith based on the higher H2 yield observed with... 

Figure 1. Yields of H2, CO, CO2, and CH4 (mole/mole of isooctane) from Reforming Isooctane Catalyzed by Rh-, Ni-, or Pt-CGO Supported on a Cordierite Monolith. Conditions 700°C, 02/C=0.5, H20/C=1.2, GHSV=11,000 h l.

---